PATENT DOCUMENT

Publication Number: US-10868648-B2
Application Number: US-201715804786-A
Country: US
Kind Code: B2

Title: Method, apparatus and system for managing bearers in a wireless communication system

Abstract:
Embodiments of the present disclosure describe methods, apparatuses, and systems for managing bearers in a wireless communication system. In some embodiments, an apparatus, to be employed by a user equipment (UE), may comprise a communication module to: communicate with a core network on a first bearer through a master evolved Node B (MeNB); receive, from the MeNB, a first message of reconfiguring a radio resource control (RRC) connection to establish a second bearer between the UE and the core network and through a secondary eNB (SeNB); synchronize, in response to the message, with the SeNB in order to establish the second bearer; and communicate with the core network on the second bearer through the SeNB, and continue communicating with the core network on the first bearer through the MeNB.

Claims:
What is claimed is: 
     
       1. One or more non-transitory, computer-readable media having instructions that, when executed, cause a master evolved Node B (“MeNB”) to:
 detect a condition to initiate a dual-connectivity operation for a user equipment (“UE”); 
 select, based on detection of the condition, a secondary evolved Node B (“SeNB”) to establish an evolved universal terrestrial radio access network radio access bearer (“E-RAB”) for the dual-connectivity operation, the E-RAB to include an S1 bearer between the MeNB and a core network and a data radio bearer between the SeNB and the UE: 
 generate an addition request to request the SeNB to establish the E-RAB; 
 cause transmission of the addition request to the SeNB; 
 generate an E-RAB setup message for a mobility management entity (“MME”), the E-RAB setup message indicating that the SeNB is capable of handling the E-RAB; and 
 cause transmission of the E-RAB setup message to the MME. 
 
     
     
       2. The one or more non-transitory, computer-readable media of  claim 1 , wherein the addition request includes a list of E-RABs to be setup. 
     
     
       3. The one or more non-transitory, computer-readable media of  claim 1 , wherein the addition request includes security capabilities of the UE. 
     
     
       4. The one or more non-transitory, computer-readable media of  claim 1 , wherein the addition request is an X2 message to be transmitted over an X2 interface. 
     
     
       5. The one or more non-transitory, computer-readable media of  claim 1 , wherein the instructions, when executed, further cause the MeNB to:
 process an addition request acknowledgement received from the Se NB in response to the addition request. 
 
     
     
       6. The one or more non-transitory, computer-readable media of  claim 5 , wherein the addition request acknowledgement includes a list of admitted ERABs. 
     
     
       7. The one or more non-transitory, computer-readable media of  claim 1 , wherein the instructions, when executed, further cause the MeNB to:
 generate an RRC connection reconfiguration message to include small cell information to facilitate establishment of a connection with the SeNB; and 
 cause the RRC connection reconfiguration message to be transmitted to the UE. 
 
     
     
       8. The one or more non-transitory, computer-readable media of  claim 1 , wherein the addition request is an SeNB addition request. 
     
     
       9. The or more non-transitory, computer-readable media of  claim 1 , wherein the instructions, when executed, further cause the MeNB to:
 generate a release request to be sent to the SeNB to request that the SeNB release the E-RAB used by the UE for dual-connectivity operation; and 
 cause transmission of the release request to the SeNB. 
 
     
     
       10. An apparatus to be implemented in a master evolved Node B (“MeNB”), the apparatus comprising:
 communication circuitry to: detect a condition to initiate a dual-connectivity operation for a user equipment (“UE”); select, based on detection of the condition, a secondary evolved Node B (“SeNB”) to establish an evolved universal terrestrial radio access network radio access bearer (“E-RAB”) for dual connectivity operation of a user equipment (“UE”); generate an addition request to request the SeNB to establish the E-RAB, the E-RAB to include an S1 bearer between the MeNB and a core network and a data radio bearer between the SeNB and the UE; and generate an E-RAB setup message for a mobility management entity (“MME”), the E-RAB setup message indicating that the SeNB is capable of handling the E-RAB; and 
 X2 interface circuitry to cause the addition request to be transmitted to the SeNB. 
 
     
     
       11. The apparatus of  claim 10 , wherein the addition request includes a list of E-RABs to be setup. 
     
     
       12. The apparatus of  claim 10 , wherein the addition request includes security capabilities of the UE. 
     
     
       13. The apparatus of  claim 10 , wherein the addition request is an X2 message. 
     
     
       14. The apparatus of  claim 10 , wherein the instructions, when executed, further cause the MeNB to:
 process an addition request acknowledgement received from the Se NB in response to the addition request. 
 
     
     
       15. The apparatus of  claim 14 , wherein the addition request acknowledgement includes a list of admitted E-RABs. 
     
     
       16. The apparatus of  claim 10 , wherein the communication circuitry is further to:
 generate an RRC connection reconfiguration message to include small cell information to facilitate establishment of a connection with the SeNB; and 
 cause the RRC connection reconfiguration message to be transmitted to the UE. 
 
     
     
       17. An apparatus to be implemented in a master evolved Node B (“MeNB”), the apparatus comprising:
 means for choosing a small cell for evolved packet system (“EPS”) bearer establishment to provide dual-connectivity for a user equipment (“UE”); 
 means for sending, to a secondary evolved node B (“SeNB”) that is to provide the small cell, an addition request to request the SeNB to establish an evolved universal terrestrial radio access network radio access bearer (“E-RAB”), the E-RAB to include an S1 bearer between the MeNB and a core network and a data radio bearer between the SeNB and the UE; 
 means for receiving, from the Se NB, an addition request acknowledgment that includes a list of established E-RABs; and 
 means for generating an E-RAB setup message for a mobility management entity (“MME”), the E-RAB setup message indicating that the SeNB is capable of handling the E-RAB. 
 
     
     
       18. The apparatus of  claim 17 , further comprising:
 means for transmitting, to the UE, an RRC connection reconfiguration message that includes small cell information to facilitate establishment of a connection with the Se NB. 
 
     
     
       19. The apparatus of  claim 18 , further comprising:
 means for receiving, from the UE, an RRC connection reconfiguration complete message after the UE synchronizes with the SeNB.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 14/653,221, 371 filing date Jun. 17, 2015, entitled “METHOD, APPARATUS AND SYSTEM FOR MANAGING BEARERS IN A WIRELESS COMMUNICATION SYSTEM,” which is national phase entry under 35 U.S.C. 371 of International Application No. PCT/US2013/077294, filed Dec. 20, 2013, entitled “METHOD, APPARATUS AND SYSTEM FOR MANAGING BEARERS IN A WIRELESS COMMUNICATION SYSTEM”, which claims priority to U.S. Provisional Patent Application No. 61/753,914, filed Jan. 17, 2013, the entire disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     FIELD 
     Embodiments of the present disclosure generally relate to the field of wireless communication systems, and more particularly, to bearer management in the wireless communication systems. 
     BACKGROUND 
     With explosion of mobile broadband data, advent of a small cell, also known as a pico cell, may help to increase service coverage and/or mobile network capacities. The small cell may provide radio coverage from several meters to several kilometers. However, coexistence of macro cells and small cells in the network and frequent handovers between the macro cell and the small cell when a user equipment (UE) moves into or out of the small cell, may create a big challenge to current wireless standard technologies, such as 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) project. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. 
         FIG. 1  illustrates an embodiment of a wireless communication network having coverage from a number of macro cells and small cells. 
         FIG. 2  illustrates an embodiment of a wireless communication system that may operate in compliance with the 3GPP LTE project along with any amendments, updates and/or revisions. 
         FIG. 3  illustrates an embodiment of a signalling procedure for the wireless communication system to add a new bearer through a secondary evolved Node B (SeNB) of the wireless communication system. 
         FIG. 4  illustrates an embodiment of a method for a user equipment (UE) of the wireless communication system to add the new bearer. 
         FIG. 5  illustrates an embodiment of a method for a master evolved Node B (MeNB) of the wireless communication system to add the new bearer. 
         FIG. 6  illustrates an embodiment of a signalling procedure to switch a bearer from the MeNB to the SeNB of the wireless communication system, based on a S1 approach. 
         FIG. 7  illustrates an embodiment of a signalling procedure to switch the bearer from the MeNB to the SeNB of the wireless communication system, based on an X2 approach. 
         FIG. 8  illustrates an embodiment of a method for the UE of the wireless communication system to switch the bearer from the MeNB to the SeNB. 
         FIG. 9  illustrates an embodiment of a method for the MeNB of the wireless communication system to switch the bearer from the MeNB to the SeNB, based on the S1 approach. 
         FIG. 10  illustrates an embodiment of a method for the MeNB of the wireless communication system to switch the bearer from the MeNB to the SeNB, based on the X2 approach. 
         FIG. 11  illustrates an embodiment of a method for the SeNB of the wireless communication system to switch the bearer from the MeNB to the SeNB based on the S1 approach. 
         FIG. 12  illustrates an embodiment of a method for the SeNB of the wireless communication system to switch the bearer from the MeNB to the SeNB based on the X2 approach. 
         FIG. 13  illustrates an embodiment of a signalling procedure for the wireless communication system to switch a bearer from the SeNB to the MeNB, based on the S1 approach. 
         FIG. 14  illustrates an embodiment of a signalling procedure for the wireless communication system to switch the bearer from the SeNB to the MeNB, based on the X2 approach. 
         FIG. 15  illustrates an embodiment of a method for the UE of the wireless communication system to switch the bearer from the SeNB to the MeNB. 
         FIG. 16  illustrates an embodiment of a method for the MeNB of the wireless communication system to switch the bearer from the SeNB to the MeNB, based on the S1 approach. 
         FIG. 17  illustrates an embodiment of a method for the MeNB of the wireless communication system to switch the bearer from the SeNB to the MeNB, based on the X2 approach. 
         FIG. 18  illustrates an embodiment of a method for the SeNB of the wireless communication system to switch the bearer from the SeNB to the MeNB, based on the S1 approach. 
         FIG. 19  illustrates an embodiment of a method for the SeNB of the wireless communication system to switch the bearer from the SeNB to the MeNB, based on the X2 approach. 
         FIG. 20  illustrates an embodiment of a signalling procedure for the wireless communication system to switch a bearer from a source SeNB to a target SeNB, based on the S1 approach. 
         FIG. 21  illustrates an embodiment of a signalling procedure for the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the X2 approach. 
         FIG. 22  illustrates an embodiment of a method for the UE of the wireless communication system to switch the bearer from the source SeNB to the target SeNB. 
         FIG. 23  illustrates an embodiment of a method for the MeNB of the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the S1 approach. 
         FIG. 24  illustrates an embodiment of the method for the MeNB of the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the X2 approach. 
         FIG. 25  illustrates an embodiment of a method for the source SeNB of the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the S1 approach. 
         FIG. 26  illustrates an embodiment of a method for the source SeNB of the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the X2 approach. 
         FIG. 27  illustrates an embodiment of a method for the target SeNB of the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the S1 approach. 
         FIG. 28  illustrates an embodiment of a method for the target SeNB of the wireless communication system to switch the bearer from the source SeNB to the target SeNB, based on the X2 approach. 
         FIG. 29  illustrates an embodiment of an example system. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the subject matter of the present disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents. 
     Various operations are described as multiple discrete operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations may not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiment. Various additional operations may be performed and/or described operations may be omitted in additional embodiments. 
     For the purposes of the present disclosure, the phrase “A/B” means “A or B”. The phrase “A and/or B” means “(A), (B), or (A and B)”. The phrase “at least one of A, B and C” means “(A), (B), (C), (A and B), (A and C), (B and C) or (A, B and C)”. The phrase “(A) B” means “(B) or (A B)”, that is, A is optional. 
     The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. 
     As used herein, the term “module” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described, without departing from the scope of the embodiments of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that the embodiments of the present disclosure be limited only by the claims and the equivalents thereof. 
     Embodiments describe several ways a UE can take advantage of pico+macro coverage by using both the macro cell and the small cell to carry data. Different approaches proposed include: small cell initial establishment; small cell addition; small cell release; and small cell switch. 
     For small cell initial establishment, the UE may have a single EPS bearer established and the UE may be under the coverage of both a macro and a small eNB. The EPS bearer may be established via the macro eNB. A second bearer establishment may be requested (either mobile initiated or network initiated). The network may establish the second bearer via the small eNB. 
     For small cell addition, the UE may have one or more bearers established and the UE may be under the coverage of a macro eNB. All EPS bearers may be established via the macro cell. The UE may enter the coverage area of a small cell and the network may move one or more EPS bearers to the small eNB. 
     For small cell release, the UE may be moving out of the coverage of small eNB, DRBs between small eNB and UE may be switched to macro eNB. 
     For small cell switch, the UE may be moving from the coverage of the small eNB to another small eNB, DRBs between the small eNB and the UE may be switched to the other small eNB accordingly. 
     This disclosure introduces several X2 messages that may be used in various signalling procedures as described herein. The X2 messages may include the following. 
     X2 message SCELL ADDITION REQUEST. The macro eNB may send this message to the small eNB passing necessary information to prepare switching the DRBs from macro eNB to the small eNB. This message may contain information elements (“IEs”) like cause, E-RABs to be Setup list, Source to Target Transparent Container, UE Security Capabilities, Security Context. The UE Security Capabilities and Security Context may not be needed if X2 approach is used. 
     X2 message SCELL ADDITIONAL REQUEST ACKNOWLEDGE. The small eNB may send this message to macro eNB after receiving SCELL ADDITION REQUEST and perform admission control. SCELL ADDITION REQUEST ACKNOWLEDGE message may include E-RABs Admitted List, E-RABs Not Admitted List, and a transparent container to be sent to the UE for SCell addition. The container may include a new C-RNTI, small eNB security algorithm identifiers for the selected security algorithms, a dedicated RACH preamble, and other parameters (e.g., access parameters, SIBs, etc.). Small eNB security algorithm identifiers for the selected security algorithms may not be needed if X2 approach is used. 
     X2 message SCELL ADDITION COMPLETE. Macro eNB may send this message to small eNB to indicate that a UE has successfully added a small cell as an SCell. 
     X2 message SCELL RELEASE REQUEST. Macro eNB may send this message to a small eNB to pass necessary information to prepare switching the DRBs back to the macro eNB. This message may contain IEs like UE C-RNTI in small cell and Cause. 
     X2 message SCELLRELEASEREQUESTACKNOWLEDGE. The small eNB may send this message to the macro eNB to acknowledge the request of switching the DRBs back to the macro eNB. This message may contain IEs like C-RNTI and Cause. 
     X2 message SCELLRELEASECOMPLETE. Macro eNB may sends this message to small eNB to indicate that UE has successfully released a small cell. 
     X2 message SCELLSWITCHREQUEST. Macro eNB may send this message to both source small eNB and target small eNB to prepare the switch. This message can include a TYPE field, which may indicate whether the small eNB receiving the message will add DRBs or release DRBs. It may also include information like the E-RABs to setup or release and security information. 
     X2 message SCELLSWITCHREQUESTACKNOWLEDGE. The small eNBs may send this message to the macro eNB to acknowledge the request of switching the DRBs. 
     X2 message SCELLSWITCHCOMPLETE. Macro eNB may send this message to source small eNB and target small eNB to indicate that UE has successfully switched related RABs from source small cell to target small cell. 
     X2 message SCELLSNSTATUSTRANSFER. Macroe NB may send this message to source small eNBs to request it to transfer SN status to target small eNB. This message may include the UE C-RNTI and target cell ID. 
     In this disclosure, we extend RRCConnectionReconfiguration message by including the IE smallSCellInformation. This IE inform the UE that a secondary cell is added as dual connectivity. The IE smallSCellInformation may include C-RNTI (this might not be needed if UE is allocated same C-RNTI in macro cell and small cell), security algorithm identifiers, and dedicated RACH preamble for the small cell. The security algorithm identifiers may not be needed if X2 approach is used. The RRCConnectionReconfiguration message can be also extended to include ID smallSCellRelease. This IE may inform the UE that a secondary cell is released. 
     In some embodiments, the sCellToAddModList, which may be used for SCell addition/modification in Rel-10 CA, can be reused and add new parameters, e.g., C-RNTI, security algorithm identifiers, and dedicated RACH preamble for the small cell if necessary. Then sCellToAddModList can implement the functionality of small SCellInformation or smallSCellRelease. 
       FIG. 1  illustrates an embodiment of a wireless communication network  100  that may operate in compliance with Long Term Evolution (LTE) standards of 3rd Generation Partnership Project (3GPP). The wireless communication network  100  may have coverage from a number of macro cells and small cells. As illustrated in the  FIG. 1 , a hexagon cell may represent a macro cell, and an elliptical cell may represent a small cell. In various embodiments, the small cell may be placed inside of the macro cells or on a border of the macro cell. The small cell, also known as the pico cell, may provide radio coverage from several meters to several kilometers. On the contrary, in some cases, the macro cell may have radio coverage of a few tens of kilometers. 
       FIG. 2  illustrates an embodiment of a wireless communication system  200  that may operate in compliance with the 3GPP LTE project along with any amendments, updates, and/or revisions (e.g., LTE-Advanced (LTE-A), etc.). The wireless communication system  200  may comprise a user equipment (UE)  201 , a master evolved Node B (MeNB)  202  for the macro cell, a secondary evolved Node B (SeNB)  203  for the small cell, and a core network system  204 , wherein the UE  201  may be dual-connected with the MeNB  202  and the SeNB  203  according to a S1 approach or an X2 approach. Other embodiments may implement other modifications and variations on the MeNB  202  and/or the SeNB  203 . For example, the MeNB  202  may be designed for another small cell. Similarly, the SeNB  203  may be designed for another macro cell. 
     The UE  201  may be embodied as, without limitation, a smart phone, a cellular telephone, a tablet, a consumer electronic device, a laptop computer, a notebook computer, a mobile computing system, a processor-based system, and/or any other mobile communication device configured to communicate with the core network system  204  via the MeNB  202  and/or the SeNB  203 . The core network system  204  may be embodied as an evolved packet core (EPC) which may comprise, a mobility management entity (MME)  214 , a serving gateway (S-GW)  224 , a packet data network gateway (PDN GW)  234 , and others. 
     Under the dual connectivity, bearers carrying data flows between the UE  201  and the core network system  204  may split between the MeNB  202  and the SeNB  203 , for example, the bearers through the MeNB  202  and the bearers through the SeNB  203 . Examples for the bearers may include evolved packet system (EPS) bearers. In some embodiments, the EPS bearer may comprise a bearer between the UE  201  and the MeNB  202  such as a data radio bearer (DRB), a bearer between the MeNB  202  and the S-GW  224  such as a S1 bearer, a bearer between S-GW  224  and PDN GW  234  such as S5/S8 bearer, and/or others. In some embodiments, an Evolved Universal Terrestrial Radio Access Network (EUTRAN) radio access bearer (E-RAB) between the UE  201  and the S-GW  224  may identify the concatenation of the corresponding DRB and the S1 bearer. 
     According to the S1 approach, the MeNB  202  and the SeNB  203  may connect directly with the core network system  204  via a S1 interface and the bearers for different eNBs may be split at the core network system  204 . According to the X2 approach, the SeNB  203  may indirectly connect with the core network system  204 , namely, through an X2 interface of the MeNB  202 . Therefore, the bearers may be split at the MeNB  202 . 
     As illustrate in  FIG. 2 , in various embodiments, the UE  201  may include a communication module  211 , and/or others. The communication module  211  may receive or transmit a signalling/packet from/to the MeNB  202  and/or SeNB  203  in the wireless communication system  200 . In some embodiments, the communication module  211  may further generate, process and/or control the signalling/packet and/or other communications from/to the UE  201 . Details about functionalities of the communication module  211  may be provided in the following descriptions. The communication module  211  may include several layer implementations, such as a physical layer module  2110 , a L2 layer module  2111 , a radio resource communication (RRC) layer module  2112 , a non-access stratum (NAS) layer module  2113 , and/or others. 
     In various embodiments, the MeNB  202  may include a communication module  212 , and/or others. The communication module  212  may receive or transmit a signalling/packet from/to the UE  201 , SeNB  203  and/or core network system  204  in the wireless communication system  200 . In some embodiments, the communication module  212  may further generate, process and/or control the signalling/packet and/or other communications from/to the MeNB  202 . Details about functionalities of the communication module  212  may be provided in the following descriptions. The communication module  212  may include several layer implementations, such as a physical layer module  2120 , a L2 layer module  2121 , a radio resource communication (RRC) layer module  2122 , a non-access stratum (NAS) layer module  2123 , and/or others. 
     In various embodiments, the SeNB  203  may include a communication module  213 , and/or others. The communication module  213  may receive or transmit a signalling/packet from/to the UE  201 , MeNB  202  and/or core network system  204  of the wireless communication system  200 . In some embodiments, the communication module  213  may further generate, process and/or control the signalling/packet and/or other communications from/to the SeNB  203 . Details about functionalities of the communication module  213  may be provided in the following descriptions. The communication module  213  may include several layer implementations, such as a physical layer module  2130 , a L2 layer module  2131 , a radio resource communication (RRC) layer module  2132 , a non-access stratum (NAS) layer module  2133 , and/or others. 
       FIG. 3  illustrates an embodiment of a signalling procedure for the wireless communication system  200  to add SeNB resources by adding a new bearer through the SeNB  203 , such as a new EPS bearer between the UE  201  and the core network system  204  and through the SeNB  203  for the small cell. In various embodiments, the UE  201  may communicate with the core network system  204  via a default bearer (e.g., a default EPS bearer) established through the MeNB  202  for the macro cell. In order to create the new bearer through the SeNB  203 , during the signalling procedure as depicted in  FIG. 3 , the UE  201  may transmit a request to the MeNB  202  to request allocation of a new bear resource for a traffic flow aggregation (signalling  301 ). In some embodiments, the UE  201  may move into the small cell which may trigger a determination of requesting the allocation of the new bearer resource. 
     The request may be embodied as, without limitation, an uplink information transfer and a non-access stratum (NAS) bearer resource allocation request, and may include a specific quality of service (QoS) demand, a guaranteed bit rate (GBR) requirement for a new traffic flow aggregate and/or other information related to a dedicated EPS bearer context. 
     In some embodiments, the MeNB  202  may transport the request to the MME  214  (signalling  302 ), which may then transmit a bearer resource command to the S-GW  224  in response to a determination that the request is acceptable (signalling  303 ). However, in response to a determination that the request is not acceptable, the MME  214  may reject the request by transmitting a rejection message. In some embodiments, the bearer resource command may be further forwarded to the PDN GW  234  (signalling  304 ). In response to a determination that the bearer resource command may be acceptable, the PDN GW  234  may transmit a create bearer request to the S-GW  224  (signalling  305 ), which may then forward the request to the MME  214  (signalling  306 ). However, in response to a determination that the bearer resource command may be unacceptable, the PDN GW  234  may transmit a rejection message to the S-GW  224  and then indirectly to the MME  214 . 
     Upon receiving the create bearer request, the MME  214  may initiate a dedicated bearer context activation procedure by transmitting a request to setup the new bearer with dedicated bearer context (signalling  307 ). The request may be embodied as E-RAB setup request and NAS activate dedicated EPS bearer context request. 
     Upon receipt of the request from MME  214 , the MeNB  202  may select a small cell or a SeNB through which the new bearer can be established. In some embodiments, the MeNB  202  may select the small cell or the SeNB based on a UE measurement report related to a UE communication quality. The MeNB  202  may further transmit a request of adding the small cell or the SeNB by establishing the new bearer through the selected SeNB  203  (signalling  308 ). The request may be embodied as a SeNB addition request or a small cell addition request (not illustrated in  FIG. 3 ) and may include, without limitation, information element (IE) such as cause for the SeNB addition or the small cell addition, a list of E-RABs to be setup, characteristics of the new bearer (such as E-RAB parameters, transport network layer (TNL) address information, and/or others), UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In response to a determination that the request from MeNB  202  is acceptable, such as when the QoS requirement of the new bearer can be satisfied, the SeNB  203  may transmit a message, e.g., a SeNB addition request acknowledgement (ACK) or a small cell addition request ACK (not illustrated in  FIG. 3 ), to the MeNB  202  (signalling  309 ). The SeNB addition request ACK or the small cell addition request ACK may include, without limitation, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of not admitted E-RABs, a transparent container to be sent to the UE for the small cell addition or the SeNB addition, and/or others. The transparent container may include, without limitation, a new cell-radio network temporary identifier (C-RNTI) for identifying the UE  201  by the SeNB  203 , secondary eNB security algorithm identifiers for selected security algorithms, a dedicated random access channel (RACH) preamble, access parameters, system information blocks (SIBs) parameters, and/or others. However, in response to a determination that the request from MeNB  202  is unacceptable, the SeNB  203  may transmit a rejection message to the MeNB  202 . 
     Upon receipt of the acknowledgement message, the MeNB  202  may transmit a request to the UE  201  to request reconfiguring a radio resource control (RRC) connection to establish the new bearer through the SeNB  203  for the small cell (signalling  310 ). The request may be embodied as, without limitation, a RRC connection reconfiguration (i.e., RRCconnectionreconfiguration) and NAS activate dedicated EPS bearer context request, and may include information such as C-RNTI, security algorithm identifiers, dedicated RACH preamble for the small cell, and/or others. In some embodiments, the C-RNTI may not be needed if the UE  201  is allocated with the same C-RNTI in the macro cell and the small cell, and the security algorithm identifiers may not be needed if X2 approach is used. 
     Based on the information in the RRCconnectionreconfiguration and NAS activate dedicated EPS bearer request, the UE  201  may perform uplink and downlink synchronization with the SeNB  203  in order to reconfigure the RRC connection to establish the new bearer with the dedicated EPS bearer context (signalling  311 ). For example, the UE  201  may perform the synchronization to the SeNB  203  and access the small cell via RACH, following a contention-free or contention-based procedure depending on whether a dedicated preamble was indicated or not. In some embodiments, the UE  201  may meanwhile keep the default bearer through the MeNB  202  as well as a signalling radio bearer (SRB) through the MeNB  202 . In this way, the UE  201  may be dual-connected with the MeNB  202  and the SeNB  203 . Then, the UE  201  may transmit a RRC connection reconfiguration complete message (i.e., RRCconnectionreconfigurationcomplete) to the MeNB  202  (signalling  312 ), and the MeNB  202  may further transmit a SeNB addition complete message or a small cell addition complete message (not illustrated in  FIG. 3 ) to the SeNB  203  (Signalling  313 ). Alternatively, the UE  201  may transmit the RRCconnectionreconfigurationcomplete message to the MeNB  202  as well as the SeNB  203 . The UE  201  may be ready to communicate with the new bearer through the SeNB  203 , and SeNB  203  may buffer packet data received from the UE  201  until a connection with the S-GW  224  is established. 
     In some embodiments, the MeNB  202  may then transmit an E-RAB setup response to the E-RAB setup request from MME  214  (signalling  314 ). The E-RAB setup response may be embodied as, without limitation, a S1 application protocol (S1AP) E-RAB setup response for the S1 approach or an X2 application protocol (X2AP) E-RAB setup response for the X2 approach. The E-RAB setup response may inform the MME  214  that the new bearer was created and was re-directed to the SeNB  203  and may include an indicator that the E-RAB may be handled by the SeNB, an IP addresses of the SeNB, and/or others. 
     The UE  201  may further transmit a message informing the MeNB  202  that the dedicated bearer context is accepted, such as a NAS activate dedicated EPS bearer context accept message to the MeNB  202  (signalling  315 ). This message may be transmitted in response to the above-stated NAS activate dedicated EPS bearer context request. The MeNB  202  may further forward the message to the MME  214  (signalling  316 ). 
     Upon receipt of the E-RAB setup response and the NAS activate dedicated EPS bearer context accept message, the MME  214  may transmit a create bearer response to the S-GW  224  (signalling  317 ), which may be the response to the above-stated create bearer request from the S-GW  224 . In this way, the connection between the SeNB  203  and the S-GW  224  may be established, resulting in the establishment of the new bearer between the UE  201  and the S-GW  224 . 
     Other embodiments may implement other modifications and variations to on the signalling procedure as depicted in  FIG. 3 . For example, although  FIG. 3  illustrates the signalling procedure of adding the new cell as initiated by the UE  201 , it should be understood that a similar procedure as initiated by the network  204  can accomplish the similar result. 
       FIG. 4  illustrates an embodiment of a method for the UE  201  to add the SeNB resources by adding the new bearer through the SeNB  203  for the small cell. In block  401 , the communication module  211  or other device of the UE  201  may communicate with the core network system  204  on the default bearer, such as the default EPS bearer through the MeNB  202 . In block  402 , the communication module  211  or other device may determine that the new bearer is needed for the traffic flow aggregation. In some embodiments, the UE  201  may move into the small cell which may trigger the determination for the new bearer through the small cell. In block  403 , the communication module  211  (e.g., NAS layer module  2113 ) or other device may transmit the NAS bearer resource allocation request to the MeNB  202 . In block  404 , the communication module  211  (e.g., RRC layer module  2112 ) or other device may receive, from the MeNB  202 , the request of adding the new bearer through the SeNB  203  for the small cell. The request may be embodied as the RRCconnectionreconfiguration and NAS activate dedicated EPS bearer context request, and may include information such as C-RNTI, security algorithm identifiers, dedicated RACH preamble for the small cell, and/or others. In some embodiments, the C-RNTI may not be needed if the UE  201  is allocated with the same C-RNTI in the macro cell and the small cell, and the security algorithm identifiers may not be needed if X2 approach is used. 
     In block  405 , the communication module  211  (e.g., the RRC layer  2112 ) or other device may synchronize with the SeNB  203  to reconfigure the RRC connection for the new bearer establishment. In some embodiments, the UE  201  may perform uplink and downlink synchronization based on the information contained in the request. In some embodiments, the UE  201  may meanwhile keep the default bearer through the MeNB  202  as well as a signalling radio bearer (SRB) through the MeNB  202 . Thus, the UE  201  may be dual-connected with the MeNB  202  and the SeNB  203 . 
     In block  406 , the communication module  211  (e.g., the RRC layer  2112 ) or other device may transmit the RRCconnectionreconfigurationcomplete message to the MeNB  202 . In some embodiments, the message may be further transmitted to the SeNB  203 . In block  407 , the communication module  211  (e.g., the NAS layer  2113 ) or other device may transmit the NAS activate dedicated EPS bearer context accept message to the MeNB  202 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 4 . For example, although  FIG. 4  illustrates the method of adding the new bearer as initiated by the UE  201 , it should be understood that a similar procedure as initiated by the network  204  can accomplish the similar result. 
       FIG. 5  illustrates an embodiment of a method for the MeNB  202  of the wireless communication network  200  to add the SeNB resources by adding the new bearer through the SeNB  203  for the small cell. In block  501 , the communication module  212  or other device of the MeNB  202  may communicate with the UE  201  on the default bearer through the macro cell, such as the EPS bearer. In block  502 , the communication module  212  (e.g., NAS layer  2123 ) or other device may receive the NAS bearer resource allocation request from the UE  201 . In block  503 , the communication module  212  (e.g., NAS layer  2123 ) or other device may forward the NAS bearer resource allocation request to the MME  214 . In block  504 , the communication module  212  (e.g., NAS layer  2123 ) or other device may receive the E-RAB setup request and NAS activate dedicated EPS bearer context request from the MME  214 , as a part of the dedicated bearer context activation procedure. In block  505 , the communication module  212  or other device may select the small cell or the SeNB through which the new bearer can be established. In some embodiments, the MeNB  202  may select the small cell or the SeNB based on the UE measurement report related to the UE communication quality. 
     In block  506 , the communication module  212  or other device may further transmit to the SeNB  203  the request of adding the new bearer. The request may be embodied as the SeNB addition request or the Small Cell addition request and may include, without limitation, information element (IE) such as cause for the SeNB addition, a list of E-RABs to be setup, characteristics of the new bearer, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  507 , the communication module  212  or other device may receive, from the SeNB  203 , the acknowledgement message such as the SeNB addition request ACK or the small cell addition request ACK (not illustrated in  FIG. 5 ), if the SeNB  203  determines that the SeNB addition request or the small cell addition request is acceptable. The SeNB addition request ACK the small cell addition request ACK may include, without limitation, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of not admitted E-RABs, a transparent container to be sent to the UE for SeNB addition or small cell addition, and/or others. The transparent container may include, without limitation, a new cell-radio network temporary identifier (C-RNTI) for identifying the UE  201  by the SeNB  203 , secondary eNB security algorithm identifiers for selected security algorithms, a dedicated random access channel (RACH) preamble, access parameters, system information blocks (SIBs) parameters, and/or others. However, the communication module  212  or other device may receive the rejection message, if the SeNB  203  determines that the SeNB addition request or the small cell addition request is unacceptable. 
     In block  508 , the communication module  212  (e.g., RRC layer  2122 ) or other device may transmit the RRCconnectionreconfiguration and NAS activate dedicated EPS bearer context request to the UE  201  to request reconfiguring the RRC connection to establish the new bearer through the SeNB  203 . In some embodiments, the RRCconnectionreconfiguration and NAS activate dedicated EPS bearer context request may include information such as C-RNTI, security algorithm identifiers, dedicated RACH preamble for the small cell, and/or others. In some embodiments, the C-RNTI may not be needed if the UE  201  is allocated with the same C-RNTI in the macro cell and the small cell, and the security algorithm identifiers may not be needed if X2 approach is used. 
     In some embodiments, the communication module  212  (e.g., RRC layer  2122 ) or other device may receive the RRC connection reconfiguration complete message from the UE  201  in block  509 , and may transmit to MME  214  an E-RAB setup response to the E-RAB setup request in block  510 . The E-RAB setup response may be embodied as, without limitation, a S1 application protocol (S1AP) E-RAB setup response for the S1 approach or an X2 application protocol (X2AP) E-RAB setup response for the X2 approach. The E-RAB setup response may inform the MME  214  that the new bearer was created and was re-directed to the SeNB  203 . 
     In block  511 , the communication module  212  (e.g., NAS layer  2123 ) or other device may further receive the NAS activate dedicated EPS bearer context accept message from the UE  201 , which may be transmitted in response to the above-stated NAS activate dedicated EPS bearer context request. The communication module  212  (e.g., NAS layer  2123 ) or other device may further forwarded the message to the MME  214 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 5 . For example, although  FIG. 5  illustrates the method of adding the new bearer as initiated by the UE  201 , it should be understood that a similar procedure as initiated by the network  204  can accomplish the similar result. 
       FIG. 6  illustrates an embodiment of a signalling procedure to adding the SeNB resources by switching a bearer from the MeNB  202  to the SeNB  203  of the wireless communication system  200 , based on the S1 approach. 
     As illustrated in  FIG. 6 , based on the S1 approach, the UE  201  may communication with the core network system  204  over a DRB of an EPS bearer established through the MeNB  202  for the macro cell. The MeNB  202  may transmit a message related to measurement control to the UE  201  (signalling  601 ). In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, the UE  201  may perform the measurement procedures and transmit a measurement report to the MeNB  202  (signalling  602 ). Based on the measurement report, the MeNB  202  may make a decision of switching the DRB from the macro cell to the small cell. This may happen under certain circumstances, such as when the UE  201  moving into the coverage of the small cell. As illustrated in  FIG. 6 , the decision may be called as a carrier aggregation (CA) decision. On the other hand, although not being illustrated in  FIG. 6 , it should be understood that the MeNB  202  may make a decision of not adding the small cell, for example, when the measurement report indicates that the radio quality in the small cell is not good enough. 
     The MeNB  202  may send a request of adding the small cell to the SeNB  203  for the small cell (signalling  603 ). The request may be embodied as a SeNB addition request or a small cell addition request (not illustrated in  FIG. 6 ), and may include, without limitation, information element (IE) such as cause for the SeNB addition or the small cell addition, a list of E-RABs to be setup, characteristics of the DRB (such as DRB parameters, TNL address information and/or others), UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     Then, the SeNB  203  may perform an admission control to determine whether the request is acceptable or not. In response to a determination that the request is acceptable, the SeNB  203  may send a message to the MeNB  202 , such as a SeNB addition request ACK or a small cell addition request ACK (not illustrated in  FIG. 6 ) (signalling  604 ). The SeNB addition request ACK or the SeNB addition request or the small cell addition request ACK may include, without limitation, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of not admitted E-RABs, a transparent container to be sent to the UE for the SeNB addition or the small cell addition, and/or others. The transparent container may include, without limitation, a new C-RNTI for identifying the UE  201  by the SeNB  203 , secondary eNB security algorithm identifiers for selected security algorithms, a dedicated random access channel (RACH) preamble, access parameters, system information blocks (SIBs) parameters, and/or others. 
     Upon receipt of the acknowledgment message, the MeNB  202  may transmit to the UE  201  a message of reconfiguring the RRC connection to switch the DRB from the MeNB  202  to the SeNB  203  (signalling  605 ). The message may be embodied as, without limitation, a RRCconnectionreconfiguration message, and may include information related to the small cell or the SeNB  203  such as the new C-RNTI, SeNB security algorithm identifiers and optionally dedicated RACH preamble, SeNB system information blocks (SIBs), and/or others. 
     In some embodiments, the MeNB  202  may start to deliver buffered and in transit packet data to the SeNB  203 . Before forwarding the packet data, the MeNB  202  may transfer serial number (SN) status to the SeNB  203  (signalling  606 ). In some embodiments, the MeNB  202  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. The SeNB  203  may buffer the packet data received from the MeNB  202 , such as a memory or a data storage of the SeNB  203 . 
     Based on the information in the RRCconnectionreconfiguration message, the UE  201  may perform uplink and/or downlink synchronization with the SeNB  203  in order to reconfigure the RRC connection to switch the DRB from the macro cell to the small cell. For example, the UE  201  may perform the synchronization to the SeNB  203  and access the small cell via RACH, following a contention-free or contention-based procedure depending on whether a dedicated preamble was indicated or not. In some embodiments that the UE  201  may communication with the MeNB  202  on more than one DRBs, after switching the DRB from the macro cell to the small cell, the UE  201  may still keep remaining DRB bearer(s) (i.e., unswitched DRB(s)) with the MeNB  202  as well as a SRB with the MeNB  202 . In this way, the UE  201  may be dual-connected with the MeNB  202  and the SeNB  203 . 
     After synchronizing with the SeNB  203  and being able to access the small cell, the UE  201  may transmit a RRCconnectionreconfigurationcomplete message to the MeNB  202  to inform that the RRC connection reconfiguration has been completed and the small cell has been successfully added (signalling  607 ). The MeNB  202  may then transmit a small cell addition complete message to the SeNB  203  (Signalling  608 ). Alternatively, the UE  201  may transmit the RRCconnectionreconfigurationcomplete message to the MeNB  202  as well as the SeNB  203 . 
     In some embodiments, after the UE  201  can access the small cell, it may transmit an uplink packet to the SeNB  203  over the DRB through the small cell, which may be transferred by the SeNB  203  to the core network system  204 . The SeNB  203  may further transmit a path switch request to the MME  214  to request switching a downlink path of the EPS bearer from between the MeNB  202  and the core network system  204  to between the SeNB  203  and the core network system  204  (signalling  609 ), wherein the DRB of the EPS bearer has already been switched from the MeNB  202  to the SeNB  203 . The path switch request may include a list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs related to the MeNB  202  but not switched to the SeNB  203 , and/or the SRBs related to the MeNB  202 . In this way, the UE  201  may still be connected to the MeNB  202  while communicating with the SeNB  203 . Alternatively, the MeNB  202  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . 
     Upon receipt of the path switch request, the MME  214  may transmit a modify bearer request to the S-GW  224  to request modifying the downlink path of the listed EPS bearer(s) to go through the SeNB  203  (signalling  610 ). In response to the request, the S-GW  224  may switch the downlink path, so that the downlink packet data can be transmitted from the core network system  204  to the UE  201  through the SeNB  203 . In some embodiments, the S-GW  224  may further send an End Marker to the MeNB  202  indicating an end of downlink packet data transmission on the old path to the MeNB  202  (signalling  611 ). The MeNB  202  may send another End Marker to the SeNB  203  indicating an end of data forwarding from the MeNB  202  to the SeNB  203  (signalling  612 ). 
     After the completion of the bearer modification, the S-GW  224  may send with a modify bearer response to the MME  214  (signalling  613 ), which may trigger the MME  214  to transmit an acknowledgement message to the SeNB  203 , such as a path switch request ACK (signalling  614 ). 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 6 . For example, more than one DRBs may be switched from the MeNB  202  to the SeNB  203  in order to add the SeNB resources. For another example, the path switch request may be transmitted by the MeNB  202 , rather than by the SeNB  203  to the MME  214 . 
       FIG. 7  illustrates an embodiment of a signalling procedure to add the SeNB resources by switching the bearer from the MeNB  202  to the SeNB  203  of the wireless communication system  200 , based on the X2 approach. In some embodiments, the signalling procedure of  FIG. 7  may be similar as that of  FIG. 6 . However, due to the X2 approach, after the completion of RRC connection reconfiguration to switch the DRB(s) of the EPS bearer(s) from the MeNB  202  to the SeNB  203  (signalling  708 ), the transmissions of the packet data over the EPS bearer(s) may have to go through the SeNB  203  and then through the MeNB  202 , namely, the UE  201  may receive/transmit the packet data from/to the SeNB  203 , which may further communicate the packet data from/to the core network system  204  through the MeNB  202 . In this way, there may be no need to request the core network system  204  to modify the downlink path of the EPS bearer(s) from the MeNB  202  to the SeNB  203 . 
       FIG. 8  illustrates an embodiment of a method for the UE  201  of the wireless communication system  200  to adding the SeNB resources by switching the bearer from the MeNB  202  to the SeNB  203 . In some embodiments, the UE  201  may communication with the core network system  204  over the DRB of the EPS bearer established through the MeNB  202  for the macro cell. In block  801 , the communication module  211  or other device of UE  201  may receive, from the MeNB  201 , the message related to the measurement control which may configure the UE measurement procedures. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, in block  802 , the communication module  211  or other device of the UE  201  may perform the measurement and transmit the measurement report to the MeNB  202 . Based on the measurement report, the MeNB  202  may make the decision of adding the small cell by switching the DRB from the MeNB  202  to the SeNB  203 . This may happen under certain circumstances, such as when the UE  201  moving into the coverage of the small cell. However, it should be understood that the MeNB  202  may make a decision of not adding the small cell, for example, when the measurement report indicates that the radio quality in the small cell is not good enough. 
     In response to the decision of adding the small cell, in block  803 , the communication module  211  (e.g., RRC layer  2112 ) or other device may receive a message of reconfiguring the RRC connection to add the small cell by switching the DRB from the MeNB  202  to the SeNB  203 . The message may be embodied as, without limitation, a RRCconnectionreconfiguration message, and may include information related to the small cell such as the new C-RNTI, SeNB security algorithm identifiers and optionally dedicated RACH preamble, SeNB system information blocks (SIBs), and/or others. 
     In block  804 , based on the information in the RRCconnectionreconfiguration message, the communication module  211  (e.g., RRC layer  2112 ) or other device may perform the uplink and/or downlink synchronization with the SeNB  203  in order to reconfigure the RRC connection to switch the DRB from the MeNB  202  to the SeNB  203 . For example, the communication module  211  may perform the synchronization to the SeNB  203  and access the small cell via RACH, following a contention-free or contention-based procedure depending on whether a dedicated preamble was indicated or not. In some embodiments that the UE  201  may communication with the MeNB  202  on more than one DRBs, after switching the DRB from the macro cell to the small cell, the UE  201  may still keep the remaining DRB bearer(s) (i.e., the unswitched DRB(s)) with the MeNB  202  as well as the SRB with the MeNB  202 . In this way, the UE  201  may be dual-connected with the MeNB  202  and the SeNB  203 . 
     In block  805 , after synchronizing with the SeNB  203  and being able to access the small cell, the communication module  211  (e.g., RRC layer  2112 ) or other device may transmit the RRCconnectionreconfigurationcomplete message to the MeNB  202  and/or SeNB  203  to inform that the RRC connection reconfiguration has been completed and the small cell has been successfully added. In block  806 , the communication module  211  or other device may receive/transmit the packet data from/to the SeNB  203 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 8 . For example, more than one DRBs may be switched from the MeNB  202  to the SeNB  203  in order to add the SeNB resources. 
       FIG. 9  illustrates an embodiment of a method for the MeNB  202  of the wireless communication system  200  to add the SeNB resources by switching the bearer from the MeNB  202  to the SeNB  203 , based on the S1 approach. According to the S1 approach, in block  901 , the communication module  212  or other device of MeNB  202  may communicate the packet data between the UE  201  and the core network system  204  over the DRB of the EPS bearer established through the macro cell. In block  902 , the communication module  212  or other device may transmit the message related to the measure control to the UE  201 . In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. 
     In block  903 , the communication module  212  or other device may receive the measurement report from the UE  201 . In block  904 , based on the measurement report, the communication module  212  or other device may make the decision of adding the SeNB resources by switching the DRB from the MeNB  202  to the SeNB  203 . On the other hand, although not being illustrated in  FIG. 9 , the communication module  212  or other device may make the decision of not adding the small cell. 
     In response to the decision of adding the SeNB resources, the communication module  212  or other device may send to the SeNB  203  the request of adding the SeNB resources by switching the DRB from the MeNB  202  to the SeNB  203 , in block  905 . In some embodiments, the request may be embodied as a SeNB addition request or a small cell addition request (not illustrated in  FIG. 9 ), and may include, without limitation, information element (IE) such as cause for the SeNB addition or small cell addition, the list of E-RABs to be setup, characteristics of the DRB, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  906 , the communication module  212  or other device may receive, from the UE  201 , the acknowledgement message such as the SeNB addition request ACK or the small cell addition request ACK (not illustrated in  FIG. 9 ). In some embodiments, the SeNB addition request ACK or the small cell addition request ACK may include, without limitation, the list of admitted E-RABs (such as E-RAB parameters, TNL address information, and/or others), the list of not admitted E-RABs, a transparent container to be sent to the UE for the SeNB addition or the small cell addition, and/or others. The transparent container may include, without limitation, the new C-RNTI for identifying the UE  201  by the SeNB  203 , SeNB security algorithm identifiers for selected security algorithms, the dedicated RACH preamble, access parameters, SIBs parameters, and/or others. 
     Upon receipt of the acknowledgment message, in block  907 , the communication module  212  (e.g., RRC layer  2122 ) or other device may transmit to the UE  201  the message of reconfiguring the RRC connection to add the SeNB resources by switching the DRB from the MeNB  202  to the SeNB  203 . The message may be embodied as, without limitation, the RRCconnectionreconfiguration message, and may include information related to the small cell or the SeNB  203  such as the new C-RNTI, SeNB security algorithm identifiers and optionally dedicated RACH preamble, SeNB system information blocks (SIBs), and/or others. In some embodiments that the UE  201  may communication with the MeNB  202  on more than one DRBs, after switching the DRB from the MeNB  202  to the SeNB  203 , the UE  201  may still keep the remaining DRB bearer (i.e., the unswitched DRB) with the MeNB  202  as well as the SRB with the MeNB  202 . In this way, the UE  201  may be dual-connected with the MeNB  202  and the SeNB  203 . 
     Then, the MeNB  202  may start to deliver the buffered and in transit packet data to the SeNB  203 . Before forwarding the packet data in block  909 , the communication module  212  or other device may transfer the serial number (SN) status to the SeNB  203  in block  908 . In some embodiments, the MeNB  202  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. The SeNB  203  may buffer the packet data received from the MeNB  202 , for example, in the memory or the data storage of the SeNB  203 . 
     After the UE  201  synchronizing with the SeNB  203  and being able to access the small cell, in block  910 , the communication module  212  (e.g., RRC layer  2122 ) or other device may receive, from the UE  201 , the RRCconnectionreconfigurationcomplete message which may inform that the RRC connection reconfiguration has been completed and the SeNB resources has been successfully added. In some embodiments, the communication module  212  or other device may then transmit the SeNB addition complete message or small cell addition complete message (not illustrated in  FIG. 9 ) to the SeNB  203 , in block  911 . However, in other embodiments that the UE  201  transmits the RRCconnectionreconfigurationcomplete message to the MeNB  202  and the SeNB  203 , the block  911  may be omitted. 
     In block  912 , the communication module  212  or other device may send a S1 or X2 message to the S-GW  224 , in order to keep the bearer(s) unreleased, which bearer(s) are related to the MeNB  202  and haven&#39;t been switched to the SeNB  203 . The bearer(s) may include DRB(s) and/or SRB(s). In this way, the UE  201  may still connect with the MeNB  202 . In some embodiments, the similar message may be conveyed to the S-GW  224  by the SeNB  203 . In such case, block  912  may be omitted. 
     In block  912 , the communication module  212  or other device may receive from the core network system (e.g., S-GW  224 ), the end marker indicating the end of downlink packet data transmissions from the core network system to the MeNB  202  over the old path. In block  913 , the communication module  212  or other device may transmit, to the SeNB  203 , the end marker indicating the end of data forwarding from the MeNB  202  to the SeNB  203 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 9 . For example, the communication module  212  or other device may further transmit, to the MME  214 , the path switch request to request switching the downlink path of the EPS bearer from between the MeNB  202  and the core network system  204  to between the SeNB  203  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from the MeNB  202  to the SeNB  203 . The path switch request may include the list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs related to the MeNB  202  but not switched to the SeNB  203 , and/or the SRBs related to the MeNB  202 . In this way, the UE  201  may still be connected to the MeNB  202  while communicating with the SeNB  203 . Alternatively, the SeNB  203  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . 
       FIG. 10  illustrates an embodiment of a method for the MeNB  202  of the wireless communication system  200  to add the SeNB resources by switching the bearer from the MeNB  202  to the SeNB  203 , based on the X2 approach. 
     In some embodiments, blocks  1001  to  1011  are similar to blocks  901  to  9011  and may not be reiterated for simplicity. In block  1012 , based on X2 approach, the MeNB  202  may deliver the packet data received from the SeNB  203  to the core network system  204 , and vice versa. 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 10 . For example, the communication module  212  or other device may further transmit the path switch request to the MME  214  to request switching the downlink path of the EPS bearer from between the MeNB  202  and the core network system  204  to between the SeNB  203  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from the MeNB  202  to the SeNB  203 . The path switch request may include the list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs related to the MeNB  202  but not switched to the SeNB  203 , and/or the SRBs related to the MeNB  202 . In this way, the UE  201  may still be connected to the MeNB  202  while communicating with the SeNB  203 . Alternatively, the SeNB  203  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . 
       FIG. 11  illustrates an embodiment of a method for the SeNB  203  of the wireless communication system  200  to add the SeNB resources by switching the bearer from the MeNB  202  to the SeNB  203  based on the S1 approach. 
     In some embodiments, according to the S1 approach, the UE  201  may communication with the core network system  204  over the DRB of the EPS bearer established through the MeNB  202  for the macro cell. Under some circumstances such as when the UE  201  moving into the small cell, the MeNB  202  may make the decision of adding the SeNB resources by switching the DRB from the MeNB  202  to the SeNB  203 . 
     In block  1101 , the communication module  213  or other device of SeNB  203  may receive the request of adding the SeNB resources from the MeNB  202 . The request may be embodied as the SeNB addition request or the small cell addition request (not illustrated in  FIG. 11 ), and may include, without limitation, information element (IE) such as cause for the SeNB addition or the small cell addition, a list of E-RABs to be setup, characteristics of the DRB, UE security capabilities for S1 approach, security context for S1 approach, and/or others. In block  1102 , the communication module  213  or other device may perform the admission control to determine whether the request is acceptable or not. In response to the determination that the request is acceptable and relevant E-RAB bearer recourses can be granted, in block  1103 , the communication module  213  may send the acknowledgement message to the MeNB  202 , such as the SeNB addition request ACK or the small cell addition request ACK (not illustrated in  FIG. 11 ). The SeNB addition request ACK or the small cell addition request ACK may include, without limitation, a list of admitted E-RABs, a list of not admitted E-RABs, a transparent container to be sent to the UE for the SeNB addition or the small cell addition, and/or others. The transparent container may include, without limitation, a new C-RNTI for identifying the UE  201  by the SeNB  203 , secondary eNB security algorithm identifiers for selected security algorithms, a dedicated random access channel (RACH) preamble, access parameters, system information blocks (SIBs) parameters, and/or others. 
     In block  1104 , the communication module  213  or other device may receive the SN status transfer message and packet data forwarded from the MeNB  202 . In some embodiments, the MeNB  202  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. In block  1105 , the communication module  213  or other device may buffer the packet data received from the MeNB  202 , for example, in the memory or the data storage of the SeNB  203 . 
     After UE  201  synchronizing with the SeNB  203  and being able to access the small cell, in block  1106 , the communication module  213  (e.g., RRC layer  2132 ) or other device may receive the RRCconnectionreconfigurationcomplete message from the UE  201 . Alternatively, the communication module  213  (e.g., RRC layer  2132 ) may receive the SeNB addition complete message or the small cell addition complete message (not illustrated in  FIG. 11 ) from the MeNB  202 , either of which may inform the SeNB  203  of the completion of adding the SeNB resources. 
     When the UE  201  can access the small cell, it may transmit the uplink packet to the SeNB  203  over the DRB through the small cell, which may be transferred by the SeNB  203  to the core network system  204 . In block  1107 , the communication module  213  or other device may transmit the path switch request to the MME  214  to request switching the downlink path of the EPS bearer from between the MeNB  202  and the core network system  204  to between the SeNB  203  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from between the MeNB  202  to the SeNB  203 . The path switch request may include the list of the EPS bearer(s) whose DRBs have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs related to the MeNB  202  and not switched to the SeNB  203 , and/or the SRBs related to the MeNB  202 . In this way, the UE  201  may still be connected to the MeNB  202  while communicating with the SeNB  203 . Alternatively, the MeNB  202  may send the separate request of keeping the other bearer(s) unreleased, in which case the block  1107  may be omitted. 
     After the core network system  204  switches the downlink path of the EPS bearer from the MeNB  202  to the SeNB  203 , in block  1108 , the communication module  213  or other device may receive the acknowledgement message from the core network system  204  (e.g., the MME  214 ), such as the path switch request ACK. In block  1109 , the communication module  213  or other device may receive the end marker from the MeNB  202  indicating the end of data forwarding from the MeNB  202  to the SeNB  203 . 
     After completion of switching the DRB and adding the SeNB resources, based on the S1 approach, the UE  201  may communicate with the core network system  204  over the DRB through the SeNB  203 . 
       FIG. 12  illustrates an embodiment of a method for the SeNB  203  of the wireless communication system  200  to add the SeNB resources by switching the bearer from the MeNB  202  to the SeNB  203  based on the X2 approach. 
     In some embodiments, blocks  1201  to  1206  are similar to blocks  1101  to  1106  and may not be reiterated for simplicity. In block  1207 , after completion of switching the DRB and adding the SeNB resources, based on the X2 approach, the UE  201  may communicate with the SeNB  203  over the DRB through the small cell, which may further connect with the core network  204  via the MeNB  202 . In other words, based on the X2 approach, the communication module  213  or other device may forward the packet data, which was received from the UE  201 , to the MeNB  202  for further transmission to the core network  204 , and vice versa. 
       FIG. 13  illustrates an embodiment of a signalling procedure for the wireless communication system  200  to release SeNB resources by switching a bearer from the SeNB  203  to the MeNB  202 , based on the S1 approach. 
     As illustrated in  FIG. 13 , based on the S1 approach, the UE  201  may communicate packet data with the core network system  204  over a DRB of an EPS bearer through the SeNB  203  for the small cell. Under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate a signalling with the MeNB  202  over a SRB through the MeNB  202 . 
     In some embodiments, the MeNB  202  may transmit a message related to measurement control to the UE  201  (signalling  1301 ). In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, the UE  201  may perform the measurement procedures and transmit a measurement report to the MeNB  202  (signalling  1302 ). 
     Based on the measurement report, the MeNB  202  may make a decision of releasing the SeNB resources by switching the DRB from the SeNB  203  to the MeNB  202 . This may happen under certain circumstances, such as when the UE  201  moving out of the coverage of the small cell. As illustrated in  FIG. 13 , the decision may be called as a carrier aggregation (CA) decision. On the other hand, although not being illustrated in  FIG. 13 , it should be understood that the MeNB  202  may make a decision of not releasing the SeNB resources, for example, when the measurement report indicates that the radio quality in the small cell is good enough. 
     In response to the decision of releasing the SeNB resources, the MeNB  202  may send to the SeNB  203  for the small cell a request of releasing the SeNB resources (signalling  1303 ). The request may be embodied as a SeNB release request or a small cell release request (not illustrated in  FIG. 13 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like cause for the SeNB release or the small cell release, a list of E-RABs to be switched, characteristics of the DRB (such as DRB parameters, TNL address information, and/or others), UE C-RNTI in the small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. Then, the SeNB  203  may perform an admission control to determine whether the request is acceptable or not. In response to a determination that the request is acceptable, the SeNB  203  may send an acknowledgement message to the MeNB  202 , such as a small cell release request ACK (signalling  1304 ). The SeNB release request ACK or the small cell release request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB release or the small cell release, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of not admitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. 
     Upon receipt of the acknowledgment message, the MeNB  202  may transmit to the UE  201  a message of reconfiguring the RRC connection to release the SeNB resources by switching the DRB from the SeNB  203  to the MeNB  202  (signalling  1305 ). The message may be embodied as, without limitation, a RRCconnectionreconfiguration message and may include SeNB release information or small cell release information (i.e., SeNB release information) to inform the UE  201  that the SeNB resources are going to be released. 
     The SeNB  203  may deliver buffered and in transit packet data to the MeNB  202 . Before forwarding the packet data, the SeNB  203  may transfer SN status message to the MeNB  202  (signalling  1306 ). In some embodiments, the SeNB  203  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. The MeNB  202  may buffer the packet data received from the SeNB  203  in a memory or a data storage of the MeNB  202 . 
     In some embodiments, based on the information in the RRCconnectionreconfiguration message, the UE  201  may reconfigure the DRB to detach from the SeNB  203  in order to release the SeNB resources. Then, the UE  201  may transmit a RRCconnectionreconfigurationcomplete message to the MeNB  202  to inform that the RRC connection reconfiguration has been completed and the SeNB resources have been successfully released (signalling  1307 ). The MeNB  202  may then transmit a SeNB resources complete message or a SeNB release complete message or a small cell release complete message (not illustrated in  FIG. 13 ) to the SeNB  203 , which may include a UE identifier, a transaction identifier, and/or others (Signalling  1308 ). 
     When the UE  201  can access the macro cell over the DRB, based on the S1 approach, it may transmit an uplink packet to the MeNB  202  over the DRB, which may be transferred by the MeNB  203  to the core network system  204 . The MeNB  202  may further transmit a path switch request to the MME  214  to request switching a downlink path of the EPS bearer from between the SeNB  203  and the core network system  204  to between the MeNB  202  and the core network system  204  (signalling  1309 ), wherein the DRB of the EPS bearer has already been switched from the SeNB  203  to the MeNB  202 . The path switch request may include a list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs and/or the SRBs related to the MeNB  202 . Alternatively, the MeNB  202  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . In other embodiments, it may be the SeNB  203 , rather than the MeNB  202 , which may send the path switch request to the MME  214 . 
     Upon receipt of the path switch request, the MME  214  may transmit a modify bearer request to the S-GW  224  to request modifying the downlink path of the listed EPS bearer(s) to go through the MeNB  202  (signalling  1310 ). In response to the request, the S-GW  224  may switch the downlink path, so that the downlink packet data can be transmitted from the core network system  204  to the UE  201  through the MeNB  202  for the macro cell, based on the S1 approach. In some embodiments, the S-GW  224  may further send an End Marker to the SeNB  203  indicating an end of downlink packet data transmission on the old path (signalling  1311 ). The SeNB  203  may send another End Marker to the MeNB  202  indicating an end of data forwarding from the SeNB  203  to the MeNB  202  (signalling  1312 ). 
     After the completion of the bearer modification, the S-GW  224  may send with a modify bearer response to the MME  214  (signalling  1313 ), which may trigger the MME  214  to transmit an acknowledgement message to the MeNB  202 , such as a path switch request ACK (signalling  1314 ). 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 13 . In some embodiments, it may be the SeNB  203  which makes the decision of releasing the SeNB resources. In such case, the SeNB release request or the small cell release request may be sent from the SeNB  203  to MeNB  202 , and the SeNB release request ACK or the small cell release request ACK may be sent from the MeNB  202  to the SeNB  203 . 
       FIG. 14  illustrates an embodiment of a signalling procedure for the wireless communication system  200  to release the SeNB resources by switching the bearer from the SeNB  203  to the MeNB  202 , based on the X2 approach. 
     In some embodiments, the signalling procedure of  FIG. 14  may be similar as that of  FIG. 13 . However, due to the X2 approach, before releasing the SeNB resources, the UE  201  may receive/transmit the packet data from/to SeNB  203  over the DRB of the EPS bearer, and the SeNB  203  may then communicate the packet data with the core network system  204  through the MeNB  202 . In view of this, based on the X2 approach, there may be no need for the SeNB  203  to deliver the buffered and in transit packet data to the MeNB  202 . 
     Moreover, in some embodiments, after the completion of the RRC connection reconfiguration to switch the DRB from the SeNB  203  to the MeNB  202  (signalling  1406 ), the transmissions of the packet data between the UE  201  and the core network system  204  over the EPS bearer may only need to go through the MeNB  202 . In this way, there may be no need to request the core network system  204  to modify the downlink path of the EPS bearer from the SeNB  203  to the MeNB  202 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 14 . In some embodiments, it may be the SeNB  203  which makes the decision of releasing the SeNB resources. In such case, the SeNB release request or the small cell release request may be sent from the SeNB  203  to MeNB  202 , and the SeNB release request ACK or the small cell release request ACK may be sent from the MeNB  202  to the SeNB  203 . 
       FIG. 15  illustrates an embodiment of a method for the UE  201  of the wireless communication system  200  to release the SeNB resources by switching the bearer from the SeNB  203  to the MeNB  202 . 
     In block  1501 , the communication module  211  or other device of the UE  201  may communicate with the core network system  204  over the DRB of the EPS bearer through the SeNB  203  for the small cell. Under the dual connectivity, the communication module  211  or other device may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer through the MeNB  202  or communicate the signalling with the MeNB  202  over the SRB through the MeNB  202 . 
     In block  1502 , the communication module  211  or other device may receive the message related to the measurement control from the MeNB  202 . In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, the communication module  211  or other device may perform the measurement and may transmit the measurement report to the MeNB  202  in block  1503 . Based on the measurement report, the MeNB  202  may make the decision of releasing the SeNB resources by switching the DRB from the SeNB  203  to the MeNB  202 . This may happen under certain circumstances, such as when the UE  201  moving out of the coverage of the small cell. On the other hand, although not being illustrated in  FIG. 15 , it should be understood that the MeNB  202  may make the decision of not releasing the SeNB resources, for example, when the measurement report indicates that the radio quality in the small cell is good enough. 
     In response to the decision of releasing the small cell, the communication module  211  (e.g., RRC layer  2112 ) or other device may receive, from the MeNB  202  or SeNB  203 , the message of reconfiguring the RRC connection to release the small cell by switching the DRB from the SeNB  203  to the MeNB  202 , in block  1504 . The request may be embodied as, without limitation, a RRCconnectionreconfiguration message and may include small cell release information (i.e., SeNB release information or small cell release information) to inform the UE  201  that the small cell is going to be released. 
     In some embodiments, based on the information in the RRC connection reconfiguration message, the communication module  211  (e.g., RRC layer  2112 ) or other device may reconfigure the DRB to detach from the SeNB  203  in order to release the SeNB resources. After detaching from the SeNB  203 , the communication module  211  (e.g., RRC layer  2112 ) or other device may transmit the RRCconnectionreconfigurationcomplete message to the MeNB  202  to inform that the RRC connection reconfiguration has been completed and the SeNB resources has been successfully released, in block  1506 . In block  1507 , the communication module  211  or other device may start to communicate the packet data with the core network system  204  over the DRB through the MeNB  202 . 
       FIG. 16  illustrates an embodiment of a method for the MeNB  202  of the wireless communication system  200  to release the SeNB resources by switching the bearer from the SeNB  203  to the MeNB  202 , based on the S1 approach. 
     In some embodiments, based on the S1 approach, the UE  201  may communication with the core network system  204  over the DRB of the EPS bearer through the SeNB  203  for the small cell. Under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate the signalling with the MeNB  202  over the SRB. 
     As illustrated in  FIG. 16 , in some embodiments, the communication module  212  or other device of the MeNB  202  may transmit the message related to the measurement control to the UE  201 . In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, the UE  201  may perform the measurement procedures. In block  1602 , the communication module  212  or other device may receive the measurement report from the UE  201 . In block  1603 , based on the measurement report, the communication module  212  or other device may make the decision of releasing the SeNB resources by switching the DRB from the SeNB  203  to the MeNB  202 . This may happen under certain circumstances, such as when the UE  201  moving out of the coverage of the small cell. On the other hand, although not being illustrated in  FIG. 16 , it should be understood that the MeNB  202  may make the decision of not releasing the SeNB resources, for example, when the measurement report indicates that the radio quality in the small cell is not good enough. 
     In some embodiments, in response to the decision of releasing the SeNB resources, the communication module  212  or other device may send the request of releasing the SeNB resources to the SeNB  203 , in block  1604 . The request may be embodied as the SeNB release request or the small cell release request (not illustrated in  FIG. 16 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like cause for the SeNB release request or the small cell release, a list of E-RABs to be switched, characteristics of the DRB, UE C-RNTI in the small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  1605 , the communication module  212  or other device may receive the acknowledgement message from the SeNB  203 , if the SeNB  203  decides that the SeNB release request or the small cell release request is acceptable. The acknowledgement message may be embodied as the SeNB release request ACK or the small cell release request ACK, and may include, without limitation, information such as the C-RNTI, the cause for the SeNB release or the small cell release, a list of admitted E-RABs, a list of not admitted E-RABs, a transparent container to be sent to the UE for SeNB release or the small cell release, and/or others. 
     In some embodiments, upon receipt of the acknowledgment message, the communication module  212  (e.g., RRC layer  2122 ) or other device may transmit to the UE  201  the message of reconfiguring the RRC connection to release the SeNB resources by switching the DRB from the small cell to the macro cell, in block  1606 . The message may be embodied as, without limitation, a RRCconnectionreconfiguration message and may include the SeNB release information or the small cell release information (e.g., SeNB release information) to inform the UE  201  that the small cell is going to be released. 
     In some embodiments, before the SeNB  203  begins to deliver the buffered and in-transit packet data to the MeNB  202 , the communication module  212  or other device may receive the SN status transfer message from the SeNB  203 , in block  1607 . In some embodiments, the SeNB  203  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. The communication module  212  or other device may receive the packet data forwarded from the SeNB  203  in block  1608 , and may buffer the packet data in the MeNB  202  in block  1609 , for example, in the memory or the data storage of the MeNB  202 . 
     After the UE  201  detaches from the SeNB  203 , the communication module  212  (e.g., RRC layer  2122 ) or other device may receive, from the UE  201 , the RRCconnectionreconfigurationcomplete message informing that the RRC connection reconfiguration has been completed and the SeNB resources have been successfully released, in block  1610 . In block  1611 , the communication module  212  or other device may transmit the SeNB release request complete message or the small cell release complete message (not illustrated in  FIG. 16 ) to the SeNB  203 . 
     When the UE  201  can access the macro cell over the DRB, based on the S1 approach, the communication module  212  or other device may receive the uplink packet data from the UE  201  and then transfer it to the core network system  204  over the uplink path of the EPS bearer in block  1612 . In block  1613 , the communication module  212  or other device may further transmit the path switch request to the MME  214  to request switching the downlink path of the EPS bearer from between the SeNB  203  and the core network system  204  to between the MeNB  202  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from the SeNB  203  to the MeNB  202 . The path switch request may include the list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs and/or the SRBs related to the MeNB  202 . Alternatively, the MeNB  202  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . In other embodiments, it may be the SeNB  203 , rather than the MeNB  202 , which may send the path switch request to the MME  214 . 
     After the S-GW  224  modifies the downlink path of the EPS bearer to go through the MeNB  202 , based on the S1 approach, the communication module  212  or other device may receive the downlink packet data from the core network system  204  and then transfer it to the UE  201  over the downlink path of the EPS bearer, in block  1614 . In block  1615 , the communication module  212  or other device may receive the End Marker from the SeNB  203 , which may indicate the end of data forwarding from the SeNB  203  to the MeNB  202 . In block  1616 , the communication module  212  or other device may receive from MME  224  the acknowledgement message to the patch switch request, such as the path switch request ACK. 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 16 . In some embodiments, it may be the SeNB  203  which may make the decision of releasing the SeNB resources. In such case, the SeNB release request or the small cell release request may be sent from the SeNB  203  to MeNB  202 , rather than from the MeNB  202  to the SeNB  203 , and the SeNB release request ACK or the small cell release ACK may be sent from the MeNB  202  to the SeNB  203 , rather than from the SeNB  203  to the MeNB  202 . 
       FIG. 17  illustrates an embodiment of the method for the MeNB  202  of the wireless communication system  200  to release the SeNB resources by switching the bearer from the SeNB  203  to the MeNB  202 , based on the X2 approach. 
     In some embodiments, the method of  FIG. 17  may be similar as that of  FIG. 16 , for example, blocks  1701  to  1706  may be similar as the blocks  1601  to  1606 , and blocks  1707  to  1708  may be similar as blocks  1610  to  1611 . However, due to the X2 approach, before releasing the SeNB resources, the UE  201  may receive/transmit the packet data from/to SeNB  203  over the DRB of the EPS bearer, and the SeNB  203  may transmit/receive the packet data to/from the core network system  204  through the MeNB  202 . In view of this, based on the X2 approach, there may be no need for the SeNB  203  to deliver the buffered and in transit packet data to the MeNB  202 . 
     In some embodiments, after the completion of the RRC connection reconfiguration to switch the DRB from the SeNB  203  to the MeNB  202 , the transmissions of the packet data between the UE  201  and the core network system  204  over the EPS bearer may only need to go through the MeNB  202 . In this case, there may be no need to request the core network system  204  to modify the downlink path of the EPS bearer from the SeNB  203  to the MeNB  202 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 17 . In some embodiments, it may be the SeNB  203  which may make the decision of releasing the SeNB resources. In such case, the SeNB resources release request or the small cell release request (not illustrated in  FIG. 17 ) may be sent from the SeNB  203  to MeNB  202 , rather than from the MeNB  202  to the SeNB  203 , and the SeNB release request ACK or the small cell release ACK (not illustrated in  FIG. 17 ) may be sent from the MeNB  202  to the SeNB  203 , rather than from the SeNB  203  to the MeNB  202 . 
       FIG. 18  illustrates an embodiment of a method for the SeNB  203  of the wireless communication system  200  to release the SeNB resources by switching the bearer from the SeNB  203  to the MeNB  202 , based on the S1 approach. 
     In some embodiments, based on the S1 approach, the UE  201  may communication with the core network system  204  over the DRB of the EPS bearer through the SeNB  203  for the small cell. Under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate a signalling with the MeNB  202  over a SRB. In certain circumstances, such as when the UE  201  moving out of the coverage of the small cell back, it may be decided to release the SeNB resources by switching the DRB from the small cell to the macro cell. 
     In block  1801 , the communication module  213  or other device of the SeNB  203  may receive from the MeNB  202  the request of releasing the SeNB resources. The request may be embodied as a SeNB release request or the small cell release request, and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like cause for the SeNB release or the small cell release, a list of E-RABs to be switched, characterisitics of the DRB, UE C-RNTI in the small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  1802 , the communication module  213  or other device of the SeNB  203  may perform the admission control to determine that the request is acceptable. However, although not being illustrated in  FIG. 18 , in certain circumstances, it may be determined that the request is unacceptable. In block  1803 , in response to the determination that the SeNB release request or the small cell release request (not illustrated in  FIG. 18 ) is acceptable, the communication module  213  or other device may transmit the SeNB release request ACK or the small cell release request ACK to the MeNB  202 . The SeNB release request ACK or the small cell release request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB release or the small cell release, a list of admitted E-RABs, a list of not admitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. 
     Before delivering the buffered and in-transmit packet data, the communication module  213  or other device may transfer SN status message to the MeNB  202 , in block  1804 . In some embodiments, the SeNB  203  may transfer uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. In block  1805 , the communication module  213  or other device may deliver the buffered and in transit packet data to the MeNB  202 . 
     In some embodiments, after the UE  201  reconfigures the RRC connection to detach from the SeNB  203  in order to release the SeNB resources, the communication module  213  or other device may receive the SeNB release complete message or the small cell release complete message from the MeNB  202 . 
     In some embodiments, after the downlink path of the EPS bearer is switched from between the SeNB  203  and the core network system  204  to between the MeNB  202  and the core network system  204 , the communication module  213  or other device may receive the End Marker from the S-GW  224  indicating the end of downlink packet data transmission on the old path, in block  1807 . In block  1808 , the communication module  213  may send the another End Marker to the MeNB  202  indicating the end of data forwarding from the SeNB  203  to the MeNB  202 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 18 . In some embodiments, it may be the SeNB  203  which may make the decision of releasing the SeNB resources. In such case, the SeNB release request or the small cell release request may be sent from the SeNB  203  to MeNB  202 , rather than from the MeNB  202  to the SeNB  203 , and the SeNB release request ACK or the small cell release ACK may be sent from the MeNB  202  to the SeNB  203 , rather than from the SeNB  203  to the MeNB  202 . In some embodiments, the communication module  213  or other device may further transmit to the MME  214  the path switch request of switching the downlink path of the EPS bearer from between the SeNB  203  and the core network system  204  to between the MeNB  202  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from the SeNB  203  to the MeNB  202 . The path switch request may include the list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs and/or the SRBs related to the MeNB  202 . 
       FIG. 19  illustrates an embodiment of a method for the SeNB  203  of the wireless communication system  200  to release the SeNB resources by switching the bearer from the SeNB  203  to the MeNB  202 , based on the X2 approach. 
     In some embodiments, the method of  FIG. 19  may be similar as that of  FIG. 18 . For example, blocks  1902  to  1904  may be similar as the blocks  1801  to  1803 , and block  1905  may be similar as block  1806 . However, due to the X2 approach, before releasing the SeNB resources, the communication module  213  or other device may receive/transmit the packet data from/to UE  201  over the DRB of the EPS bearer, and then may communicate the packet data with the core network system  204  through the MeNB  202 , in block  1901 . In view of this, based on the X2 approach, there may be no need for the SeNB  203  to deliver the buffered and in transit packet data to the MeNB  202 . 
     Moreover, in some embodiments, after the completion of the RRC connection reconfiguration to switch the DRB from the SeNB  203  to the MeNB  202 , the transmissions of the packet data between the UE  201  and the core network system  204  over the EPS bearer may only need to go through the MeNB  202 . In this way, there may be no need to request the core network system  204  to modify the downlink path of the EPS bearer from the SeNB  203  to the MeNB  202 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 19 . In some embodiments, it may be the SeNB  203  which may make the decision of releasing the SeNB resources. In such case, the SeNB resources release request or the small cell release request (not illustrated in  FIG. 19 ) may be sent from the SeNB  203  to MeNB  202 , rather than from the MeNB  202  to the SeNB  203 , and the SeNB resources release request ACK or the small cell release request ACK (not illustrated in  FIG. 19 ) may be sent from the MeNB  202  to the SeNB  203 , rather than from the SeNB  203  to the MeNB  202 . 
       FIG. 20  illustrates an embodiment of a signalling procedure for the wireless communication system  200  to switch the SeNB resources by switching a bearer from a source SeNB to a target SeNB, based on the S1 approach. 
     As illustrated in  FIG. 20 , the wireless communication system  200  may comprise the UE  201 , the MeNB  202 , a source SeNB  2030  for a source small cell, a target SeNB  2040  for a target small cell, and the core network system  204  made up by the MME  214 , the S-GW  224  and others. In some embodiments, based on the S1 approach, the UE  201  may be dual-connected with the MeNB  202  and the source SeNB  2030 . Similarly as the SeNB  203 , the source SeNB  2030  may include a communication module  2031 , and/or others. The communication module  2031  may receive or transmit a signalling/packet from/to the UE  201 , MeNB  202 , target SeNB  2040  and/or the core network system  204  of the wireless communication system  200 . In some embodiments, the communication module  2031  may further generate, process and/or control the signalling/packet and/or other communications from/to the source SeNB  2030 . Details about functionalities of the communication module  2031  may be provided in the following descriptions. Although not being illustrated in  FIG. 20 , the communication module  2031  may further include several layer implementations, such as a physical layer module, a L2 layer module, a radio resource communication (RRC) layer module, a non-access stratum (NAS) layer module, and/or others. 
     Similarly, the target SeNB  2040  may include a communication module  2041 , and/or others. The communication module  2041  may receive or transmit a signalling/packet from/to the UE  201 , MeNB  202 , source SeNB  2030  and/or the core network system  204  of the wireless communication system  200 . In some embodiments, the communication module  2041  may further generate, process and/or control the signalling/packet and/or other communications from/to the source SeNB  2030 . Details about functionalities of the communication module  2041  may be provided in the following descriptions. Although not being illustrated in  FIG. 20 , the communication module  2041  may further include several layer implementations, such as a physical layer module, a L2 layer module, a radio resource communication (RRC) layer module, a non-access stratum (NAS) layer module, and/or others. 
     In some embodiments, based on the S1 approach, the UE  201  may communicate packet data from/to the source SeNB  2030  for the source small cell over a DRB of an EPS bearer. Under the dual-connectivity, the UE  201  may communicate another packet data from/to the MeNB  202  on another DRB of another EPS bearer, or communicate signalling with the MeNB  202  on a SRB. 
     The MeNB  202  may transmit a message related to measurement control to the UE  201  (signalling  2001 ). In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, the UE  201  may perform the measurement procedures and transmit a measurement report to the MeNB  202  (signalling  2002 ). 
     Based on the measurement report, the MeNB  202  may make a decision of switching the SeNB resources by switching the DRB from the source SeNB  2030  to the target SeNB  2040 . This may happen under certain circumstances, such as when the UE  201  moving from the source small cell to the target small cell. As illustrated in  FIG. 20 , the decision may be called as a carrier aggregation (CA) decision. On the other hand, although not being illustrated in  FIG. 20 , it should be understood that the MeNB  202  may make a decision of not switching the SeNB resources, for example, when the measurement report indicates that the radio quality in the source small cell is good enough. 
     In response to the decision of switching the SeNB resources, the MeNB  202  may send a request of switching the SeNB resources to the target SeNB  2040  for the target small cell (signalling  2003 ), as well as to the source SeNB  2040  for the source small cell (signalling  2005 ). The request may be embodied as a SeNB switch request or a small cell switch request (not illustrated in  FIG. 20 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like TYPE field indicating whether the SeNB receiving the message may add the DRB (i.e., the target SeNB) or release the DRB (i.e., the source SeNB), cause for the SeNB switch or the small cell switch, a list of E-RABs to be setup or released, characteristics of the DRB (such as DRB parameters, TNL address information, and/or others), a UE C-RNTI in the source small cell or the target small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In response to the SeNB switch request or the small cell switch request, the target SeNB  2040  may perform an admission control to determine whether the request is acceptable or not, namely, whether it is admittable to add the DRB into the target small cell. In response to a determination that the request is acceptable, the target SeNB  2040  may send a message to the MeNB  202 , such as a SeNB switch request ACK or a small cell switch request ACK (not illustrated in  FIG. 20 ) (signalling  2004 ). The SeNB switch request ACK or the small cell switch request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB switch or the small cell switch, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of not admitted E-RABs, a transparent container to be sent to the UE for SeNB release or the small cell release, and/or others. 
     On the other hand, the source SeNB  2030  may perform another admission control to determine whether the SeNB switch request or the small cell switch request is acceptable or not, namely, whether it is admittable to release the DRB from the source small cell. In response to a determination that the request is acceptable, the source SeNB  2030  may send a message to the MeNB  202 , such as a SeNB switch request ACK or a small cell switch request ACK (not illustrated in  FIG. 20 ) (signalling  2006 ). The SeNB switch request ACK or the small cell switch request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB switch or the small cell switch, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of unadmitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. 
     Upon receipt of the acknowledgment messages from the source SeNB  2030  and the target SeNB  2040 , the MeNB  202  may transmit to the UE  201  a message of reconfiguring the RRC connection to switch the SeNB resources by switching the DRB from the source small cell to the target small cell (signalling  2007 ). The request may be embodied as, without limitation, a RRCconnectionreconfiguration message and may include information necessary for switching the small cell, such as the sources SeNB information, the source small cell information, the target SeNB information, target small cell information and/or others. 
     In some embodiments, in order to trigger the delivery of buffered and in-transit packet data from the source SeNB  2030  to the target SeNB  2040 , the MeNB  202  may transmit a SeNB SN status transfer message or a small cell SN status transfer message (not illustrated in  FIG. 20 ) to the source SeNB  2030  to request it to transfer the buffered and in-transit packet data to the target SeNB  2040  (signalling  2008 ). The SeNB SN status transfer message or the small cell SN status transfer message may include, without limitation, the UE RNTI in the target small cell, the target SeNB information such as a target SeNB identifier, the target small cell information such as a target small cell identifier, and others. Then, the source SeNB  2030  may start to deliver the buffered and in-transit packet data to the target SeNB  2040 . Before forwarding the packet data, the source SeNB  2030  may transfer a SN status message to the target SeNB  2040  (signalling  2009 ). In some embodiments, the source SeNB  2030  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. The target SeNB  2040  may buffer the packet data received from the SeNB  203 , for example, in a memory or data storage of the target SeNB  2040 . 
     In some embodiments, based on the information in the RRCconnectionreconfiguration message, the UE  201  may reconfigure the RRC connection to detach from the source SeNB  2030  and synchronize to the target SeNB  2040  in order to switch from the source SeNB  2030  to the target SeNB  2040 . For example, the UE  201  may perform the synchronization to the target SeNB  2040  and access the target small cell via RACH, following a contention-free or contention-based procedure depending on whether a dedicated preamble was indicated or not. 
     After synchronizing with the target SeNB  2040  and being able to access the target small cell, the UE  201  may transmit a RRC connection reconfiguration complete message to the MeNB  202  to inform that the RRC connection reconfiguration has been completed and the SeNB resources or the small cell have been successfully switched (signalling  2010 ). The MeNB  202  may then transmit a SeNB switch complete message or a small cell switch complete message (not illustrated in  FIG. 20 ) to the source SeNB  2030  (signalling  2011 ) and the target SeNB  2040  (signalling  2012 ). Alternatively, the UE  201  may send the RRCconnectionreconfigurationcomplete message to the MeNB  202  as well as the target SeNB  2040 , so that the SeNB switch complete message or the small cell switch complete message from the MeNB  202  to the target SeNB  2040  can be omitted. 
     When the UE  201  can access the target small cell, based on the S1 approach, it may transmit an uplink packet to the target SeNB  2040  over the DRB, which may be transferred by the target SeNB  2040  to the core network system  204 . The target SeNB  2040  may further transmit a path switch request to the MME  214  to request switching a downlink path of the EPS bearer from between the source SeNB  2030  and the core network system  204  to between the target SeNB  2040  and the core network system  204  (signalling  2013 ), wherein the DRB of the EPS bearer has already been switched from the source SeNB  2030  to the target SeNB  2040 . The path switch request may include a list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs and/or the SRBs related to the MeNB  202 . Alternatively, the MeNB  202  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . In other embodiments, it may be the MeNB  202  rather than the target SeNB  2040  which may send the path switch request to the MME  214 . 
     Upon receipt of the path switch request, the MME  214  may transmit a modify bearer request to the S-GW  224  to request modifying the downlink path of the listed EPS bearer(s) to go through the target SeNB  2040  (signalling  2014 ). In response to the request, the S-GW  224  may switch the downlink path, so that the downlink packet data can be transmitted from the core network system  204  to the UE  201  through the target SeNB  2040 , based on the S1 approach. In some embodiments, the S-GW  224  may further send an End Marker to the source SeNB  2030  indicating an end of downlink packet data transmission on the old path (signalling  2015 ). The source SeNB  2030  may send an End Marker to the target SeNB  2040  indicating an end of data forwarding from the source SeNB  2030  to the target SeNB  2040  (signalling  2016 ). 
     After the completion of the bearer modification, the S-GW  224  may send with a modify bearer response to the MME  214  (signalling  2017 ), which may trigger the MME  214  to transmit an acknowledgement message to the target SeNB  2040 , such as a path switch request ACK (signalling  2018 ). 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 20 . In some embodiments, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB switch request or the small cell switch request may be sent from the source SeNB  2030  to MeNB  202  as well as the target SeNB  2040 , and the SeNB switch request ACK or the small cell switch request ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 21  illustrates an embodiment of a signalling procedure for the wireless communication system  200  to switch the SeNB resources by switching the bearer from the source SeNB  2030  to the target SeNB  2040 , based on the X2 approach. 
     In some embodiments, the signalling procedure of  FIG. 21  may be similar as that of  FIG. 20 . For example, signalling  2101  to  2107  may be similar as signalling  2001  to  2007 , and signalling  2109  to  2111  may be similar as signalling  2010  to  2012 . However, due to the X2 approach, before switching the DRB of the EPS bearer from the source SeNB  2030  to the target SeNB  2040 , the source SeNB  2030  may communicate the packet data with the core network system  204  through the MeNB  202 . Moreover, in some embodiments, after the completion of the RRC connection reconfiguration to switch the DRB from the source SeNB  2030  to the target SeNB  2040 , the transmissions of the packet data between the target SeNB  2040  and the core network system  204  over the EPS bearer may still need to go through the MeNB  202 . In this way, there may be no need to request the core network system  204  to modify the downlink path of the EPS bearer from the SeNB  2030  to the target SeNB  2040 . In other words, the signalling  2013  to  2018  in  FIG. 20  may be omitted from the  FIG. 21 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 21 . In some embodiments, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB release request or the small cell release request may be sent from the source SeNB  2030  to MeNB  202  as well as the target SeNB  2040 , and the SeNB release request ACK or the small cell release request ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 22  illustrates an embodiment of a method for the UE  201  of the wireless communication system  200  to switch the SeNB resources or the small cell by switching the bearer from the source SeNB  2030  to the target SeNB  2040 . 
     In some embodiments, in block  2201 , the communication module  211  or other device of the UE  201  may communicate packet data from/to the source SeNB  2030  of the source small cell over the DRB of the EPS bearer. Under the dual connectivity, the communication module  211  or other device may communicate another packet data from/to the MeNB  202  over another DRB of another EPS bearer or communicate the signalling with the MeNB  202  over the SRB. 
     In block  2202 , the communication module  211  or other device may receive a message related to the measurement control from the MeNB  202 . In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In response to the message, the communication module  211  or other device of UE  201  may perform the measurement and may transmit the measurement report to the MeNB  202  in block  2203 . Based on the measurement report, the MeNB  202  or source SeNB  2030  may make the decision of switching the SeNB resources or the small cell by switching the DRB from the source SeNB  2030  for the source small cell to the target SeNB  2040  for the target small cell. This may happen under certain circumstances, such as when the UE  201  moving from the source small cell to the target small cell. On the other hand, although not being illustrated in  FIG. 22 , it should be understood that the MeNB  202  may make a decision of not switching the SeNB resources or the small cell, for example, when the measurement report indicates that the radio quality in the source small cell is good enough. 
     In response to the decision of switching the SeNB resources or the small cell, the communication module  211  (e.g., RRC layer) or other device may receive, from the MeNB  202 , the message of reconfiguring the RRC connection to switch the SeNB resources or the small cell by switching the DRB from the source SeNB  2030  to the target SeNB  2040 , in block  2204 . The request may be embodied as, without limitation, a RRCconnectionreconfiguration message and may include information necessary for switching the SeNB resources or the small cell, such as the source SeNB information, source small cell information, the target SeNB information, the target small cell information, and/or others. 
     In some embodiments, based on the information in the RRCconnectionreconfiguration message, the communication module  211  or other device may reconfigure the RRC connection to detach from the source SeNB  2030  and synchronize with the target SeNB  2040  in order to switch the small cell, in block  2205 . For example, the UE  201  may perform the synchronization to the target SeNB  2040  and access the target small cell via RACH, following a contention-free or contention-based procedure depending on whether a dedicated preamble was indicated or not. 
     After synchronizing with the target SeNB  2040  and being able to access the target small cell, the communication module  211  (e.g., RRC layer) or other device may transmit the RRCconnectionreconfigurationcomplete message to the MeNB  202  and/or the target SeNB  2040  to inform that the RRC connection reconfiguration has been completed and the SeNB resources or the small cell has been successfully switched, in block  2206 . In block  2207 , the communication module  211  or other device may communicate the packet data with the core network system  204  over the DRB through the target SeNB  2040 . 
       FIG. 23  illustrates an embodiment of a method for the MeNB  202  of the wireless communication system  200  to switch the SeNB resources or the small cell by switching the bearer from the source SeNB  2030  to the target SeNB  2040 , based on the S1 approach. 
     In some embodiments, based on the S1 approach, the UE  201  may communicate packet data with the core network system  204  over the DRB of the EPS bearer through the source SeNB  2030  of the source small cell. Under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate the signalling with the MeNB  202  over the SRB. 
     As illustrated in  FIG. 23 , in some embodiments, the communication module  212  or other device of the MeNB  202  may transmit the message related to measurement control to the UE  201 , in block  2301 . In some embodiments, the message may configure the UE measurement procedures according to area restriction information. Measurements provided by the MeNB  202  may assist the function controlling the UE&#39;s connection mobility. In block  2302 , the communication module  212  or other device may receive the measurement report from the UE  201 . In block  2303 , based on the measurement report, the control module  222  of the MeNB  202  may make the decision of switching the SeNB resources or the small cell by switching the DRB from the source small cell to the target small cell. This may happen under certain circumstances, such as when the UE  201  moving from the source small cell to the target small cell. Although not being illustrated in  FIG. 23 , based on the measurement report, the MeNB  202  may make a different decision, i.e., not switching the small cell. 
     In some embodiments, in response to the decision of switching the SeNB resources or the small cell, the communication module  212  or other device may send the request of switching the SeNB resources or the small cell to the target SeNB  2040 , in block  2304 . The request may be embodied as the SeNB switch request or the small cell switch request (not illustrated in  FIG. 23 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like TYPE field indicating whether the SeNB receiving the message may add the DRB (i.e., the target SeNB) or release the DRB (i.e., the source SeNB), cause for the SeNB switch or the small cell switch, a list of E-RABs to be setup or released, characteristics of the E-RABs (such as E-RAB parameters, TNL address information, and/or others), a UE C-RNTI in the source small cell or the target small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In some embodiments, in block  2305 , the communication module  212  or other device may receive the message from the target SeNB  2040 , if the target SeNB  2040  decides that the SeNB switch request or the small cell switch request (not illustrated in  FIG. 23 ) is acceptable. The message may be embodied as the SeNB switch request ACK or the small cell switch request ACK (not illustrated in  FIG. 23 ), and may include, without limitation, information such as the C-RNTI, the cause for the SeNB switch or the small cell switch, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of not admitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. 
     In some embodiments, on the other hand, the communication module  212  or other device may send the SeNB switch request or the small cell switch request (not illustrated in  FIG. 23 ) to the source SeNB  2030  in block  2306 , and may receive the SeNB switch request ACK or the small cell switch request ACK (not illustrated in  FIG. 23 ) from the source SeNB  2030  in block  2307 . 
     In some embodiments, upon receipt of the acknowledgment messages from the source SeNB  2030  and the target SeNB  2040 , the communication module  212  (e.g., RRC layer) or other device may transmit to the UE  201  the message of reconfiguring the RRC connection to switch the small cell by switching the DRB from the source SeNB  2030  to the target SeNB  2040 , in block  2308 . The request may be embodied as, without limitation, a RRCconnectionreconfiguration message and may include information necessary for switching the SeNB resources or the small cell, such as the source SeNB information, the source small cell information, the target SeNB information, the target small cell information and/or others. 
     In some embodiments, in order to trigger the delivery of buffered and in-transmit packet data from the source SeNB  2030  to the target SeNB  2040 , the communication module  212  or other device may transmit the SeNB SN status transfer message or the small cell SN status transfer message (not illustrated in  FIG. 23 ) to the source SeNB  2030  to request the transfer of the buffered and in-transit packet data to the target SeNB  2040 , in block  2309 . The SeNB SN status transfer message or the small cell SN status transfer message may include, without limitation, the UE RNTI in the target small cell, the target small cell information such as the target small cell identifier, the target SeNB information such as the target SeNB identifier, and/or others. 
     After UE  201  successfully synchronizes with the target SeNB  2040  and is able to access the target small cell, the communication module  212  (e.g., RRC layer) or other device may receive the RRCconnectionreconfiguration complete message from the UE  201  that may inform that the RRC connection reconfiguration has been completed and the SeNB resources or the small cell have been successfully switched, in block  2310 . The communication module  212  or other device may then transmit the SeNB switch complete message or the small cell switch complete message (not illustrated in  FIG. 23 ) to the source SeNB  2030  and the target SeNB  2040 , in block  2311 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 23 . For example, in some embodiments, if the UE  201  sends the RRCconnectionreconfigurationcomplete message to the MeNB  202  as well as the target SeNB  2040 , the SeNB switch complete message or the small cell switch complete message from the MeNB  202  to the target SeNB  2040  can be omitted. For another example, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB release request or the small cell release request may be sent from the source SeNB  2030  to MeNB  202  as well as the target SeNB  2040 , and the SeNB release ACK or the small cell release ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . For yet another example, the communication module  212  or other device may further transmit the path switch request to the MME  214  to request switching the downlink path of the EPS bearer from between the source SeNB  2030  and the core network system  204  to between the target SeNB  2040  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from the source SeNB  2030  to the target SeNB  2040 . The path switch request may include the list of the EPS bearer(s) whose DRB(s) have been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs and/or the SRBs related to the MeNB  202 . 
       FIG. 24  illustrates an embodiment of a method for the MeNB  202  of the wireless communication system  200  to switch the SeNB resources or the small cell by switching the bearer from the source SeNB  2030  to the target SeNB  2040 , based on the X2 approach. 
     In some embodiments, the method of  FIG. 24  may be similar as that of  FIG. 23 . For example, blocks  2401  to  2408  may be similar as blocks  2301  to  2308 , and blocks  2411 - 2412  may be similar as blocks  2310 - 2311 . However, due to the X2 approach, before switching the DRB of the EPS bearer from the source SeNB  2030  to the target SeNB  2040 , the source SeNB  2030  may communicate the packet data with the core network system  204  through the MeNB  202 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 24 . For example, in some embodiments, if the UE  201  sends the RRCconnectionreconfigurationcomplete message to the MeNB  202  as well as the target SeNB  2040 , the SeNB switch complete message or the small cell switch complete message (not illustrated in  FIG. 24 ) from the MeNB  202  to the target SeNB  2040  can be omitted. For another example, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB release request or the small cell release request (not illustrated in  FIG. 24 ) may be sent from the source SeNB  2030  to the MeNB  202  as well as to the target SeNB  2040 . Further, the SeNB release request ACK or the small cell release ACK (not illustrated in  FIG. 24 ) may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 25  illustrates an embodiment of a method for the source SeNB  2030  of the wireless communication system  200  to switch the SeNB resources or the small cell by switching the bearer from the source SeNB  2030  to the target SeNB, based on the S1 approach. 
     In some embodiments, based on the S1 approach, the UE  201  may communicate the packet data with the core network system  204  over the DRB of the EPS bearer through the source SeNB  2030  of the source small cell. Under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate the signalling with the MeNB  202  over the SRB. 
     In some embodiments, the MeNB  202  may make the decision of switching the SeNB resources or the small cell by switching the DRB from the source SeNB  2030  to the target SeNB  2040 . This may happen under certain circumstances, such as when the UE  201  moving from the source small cell to the target small cell. In such case, the communication module  2031  or other device of the source SeNB  2030  may receive, from the MeNB  202 , the request of switching the SeNB resources or the small cell, in block  2501 . The request may be embodied as the SeNB switch request or the small cell switch request (not illustrated in  FIG. 25 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like TYPE field indicating whether the SeNB receiving the message may add the DRB (i.e., the target SeNB) or release the DRB (i.e., the source SeNB), cause for the SeNB switch or the small cell switch, a list of E-RABs to be setup or released, characteristics of E-RAB (such as E-RAB parameters, TNL address information, and/or others), a UE C-RNTI in the source small cell or the target small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  2502 , the communication module  2031  or other device may perform the admission control and determine that the request is acceptable. Moreover, in bock  2502 , the communication module  2031  or other device may send the message to the MeNB  202 , such as the SeNB switch request ACK or the small cell switch request ACK (not illustrated in  FIG. 25 ). The SeNB switch request ACK or the small cell switch request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB switch or the small cell switch, a list of admitted E-RABs including TNL address information for the respective E-RAB, a list of unadmitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. 
     On the other hand, although not being illustrated in  FIG. 25 , it should be understood that the source SeNB  2030  may make a decision of not admitting the SeNB switch request or the small cell switch request, for example, when the measurement report indicates that the radio quality in the small cell is good enough 
     In block  2503 , the communication module  2031  or other device may receive, from the MeNB  202 , the SeNB SN status transfer message or the small cell SN status transfer message (not illustrated in  FIG. 25 ) which may trigger the delivery of buffered and in-transmit packet data from the source SeNB  2030  to the target SeNB  2040 . In response to the SeNB SN status transfer message or the small cell SN status transfer message, the communication module  2031  or other device may send the SN status message to the target SeNB  2040 . In some embodiments, the communication module  2031  or other device may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. Then, in block  2505 , the communication module  2031  or other device may forward the buffered and in-transit packet data to the target SeNB  2040 . 
     After the UE  201  detaches from the source small cell and synchronizes to the target small cell, the communication module  2031  or other device may receive, from the MeNB  202 , the SeNB switch complete message or the small cell switch complete message (not illustrated in  FIG. 25 ) in block  2506 , which may inform that the SeNB switch or the small cell switch has been completed. In block  2507 , the communication module  2031  or other device may receive, from the core network system  204  (e.g., S-GW  224 ), the End Marker indicating the end of downlink packet data transmission from the core network system  204  to the source SeNB  2030  on the old path. In block  2508 , the communication module  2031  or other device may send, to the target SeNB  2040 , the End Marker indicating the end of data forwarding from the source SeNB  2030  to the target SeNB  2040 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 25 . For example, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the small cell. In such case, the SeNB release request or the small cell release request may be sent from the source SeNB  2030  to MeNB  202  as well as to the target SeNB  2040 , and the SeNB release ACK or the small cell release ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 26  illustrates an embodiment of a method for the source SeNB  2030  of the wireless communication system  200  to switch the bearer from the source SeNB  2030  to the target SeNB  2040 , based on the X2 approach. 
     In some embodiments, due to the X2 approach, before switching the DRB of the EPS bearer from the source SeNB  2030  to the target SeNB  2040 , the source SeNB  2030  may communicate the packet data between the UE  201  and the core network system  204  through the MeNB  202 . In other words, the source SeNB  2030  may receive the packet data from the UE  201  and transmit it to the core network system  204  through the MeNB  202 , and/or receive the packet data from the core network system through the MeNB  202  and transmit it to the UE  201 . Further, under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate the signalling with the MeNB  202  over the SRB. 
     In some embodiments, the communication module  2031  or other device of the source SeNB  2030  may receive, from the MeNB  202 , the request of switching the SeNB resources or the small cell in block  2601 . The request may be embodied as the SeNB switch request or the small cell switch request (not illustrated in  FIG. 26 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like TYPE field indicating whether the SeNB receiving the message may add the DRB (i.e., the target SeNB) or release the DRB (i.e., the source SeNB), cause for the SeNB switch or the small cell switch, a list of E-RABs to be setup or released, characteristics of E-RAB (such as E-RAB parameters, TNL address information, and/or others), a UE C-RNTI in the source small cell or the target small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  2602 , the communication module  2031  or other device may perform the admission control and determine that the request is acceptable. Moreover, in bock  2602 , the communication module  2031  may send the message to the MeNB  202 , such as the SeNB switch request ACK or the small cell switch request ACK (not illustrated in  FIG. 26 ). The SeNB switch request ACK or the small cell switch request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB switch or the small cell switch, a list of admitted E-RABs including TNL address information for the respective E-RABs, a list of unadmitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. On the other hand, although not being illustrated in  FIG. 26 , it should be understood that the source SeNB  2030  may make the decision of not admitting the SeNB switch request or the small cell switch request. 
     In some embodiments, after the UE  201  detaches from the source small cell and synchronizes to the target small cell, the communication module  2031  or other device may receive, from the MeNB  202 , the SeNB switch complete message or the small cell switch complete message (not illustrated in  FIG. 26 ) in block  2603 , which may inform that the SeNB resources switch or the small cell switch has been completed. 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 26 . For example, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB release request or the small cell release request may be sent from the source SeNB  2030  to MeNB  202  as well as to the target SeNB  2040 . Further, the SeNB release request ACK or the small cell release request ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 27  illustrates an embodiment of a method for the target SeNB  2040  of the wireless communication system  200  to switch the bearer from the source SeNB  2030  to the target SeNB  2040 , based on the S1 approach. 
     In some embodiments, based on the S1 approach, before switching the small cell, the UE  201  may communicate the packet data with the core network system  204  over the DRB of the EPS bearer through the source SeNB  2030  of the source small cell. Under the dual connectivity, the UE  201  may communicate another packet data with the MeNB  202  over another DRB of another EPS bearer or communicate the signalling with the MeNB  202  over the SRB. 
     In some embodiments, it may be decided to switch the SeNB resources or the small cell by switching the DRB from the source SeNB  2030  to the target SeNB  2040 . This may happen under certain circumstances, such as when the UE  201  moving from the source small cell to the target small cell. In such case, the communication module  2041  or other device of the target SeNB  2040  may receive the request of switching the DRB from the MeNB  202  or the source SeNB  2030  in block  2701 . The request may be embodied as the SeNB switch request or the small cell switch request (not illustrated in  FIG. 27 ), and may include, without limitation, information necessary for preparing the DRB switch, such as elements (IE) like TYPE field indicating whether the SeNB receiving the message may add the DRB (i.e., the target SeNB) or release the DRB (i.e., the source SeNB), cause for the SeNB switch or the small cell switch, a list of E-RABs to be setup or released, characteristics of E-RAB (such as E-RAB parameters, TNL address information, and/or others), a UE C-RNTI in the source small cell or the target small cell, UE security capabilities for S1 approach, security context for S1 approach, and/or others. 
     In block  2702 , the communication device  2041  or other device may perform the admission control and determine that the request is acceptable. In block  2703 , the communication module  2041  or other device may send the message to the MeNB  202  or the source SeNB  2030 , such as the SeNB switch request or the small cell switch request ACK (not illustrated in  FIG. 27 ). The SeNB switch request ACK or the small cell switch request ACK may include, without limitation, information such as the C-RNTI, the cause for the SeNB switch or the small cell switch, a list of admitted E-RABs (such as E-RAB parameters, TNL address information, and/or others), a list of unadmitted E-RABs, a transparent container to be sent to the UE for the SeNB release or the small cell release, and/or others. On the other hand, although not being illustrated in  FIG. 27 , it should be understood that the target SeNB  2040  may make the decision of not admitting the SeNB switch request or the small cell switch request. 
     In some embodiments, in block  2704 , the communication module  2041  or other device may receive the SeNB SN status transfer message or the small cell SN status transfer message (not illustrated in  FIG. 27 ) from the source SeNB  2030 . In some embodiments, the source SeNB  2030  may convey uplink PDCP (packet data convergence protocol) SN receiver status and/or downlink PDCP SN transmitter status of E-RABs for which PDCP status preservation applies. Then, in block  2705 , the communication module  2041  or other device may receive the buffered and in-transit packet data from the source SeNB  2040 , and in block  2706 , the target SeNB  2040  may buffer the packet data, for example, in the memory or the data storage of the target SeNB  2040 . 
     In some embodiments, in response to the RRCconnectionreconfiguration message, the UE  201  may reconfigure the RRC connection to detach from the source SeNB  2030  and synchronize with the target SeNB  2040  in order to switch the DRB from the source small cell to the target small cell, in block  2707 . For example, the UE  201  may perform the synchronization to the target SeNB  2040  and access the target small cell via RACH, following a contention-free or contention-based procedure depending on whether a dedicated preamble was indicated or not. 
     After synchronizing with the UE  201  which may be able to access the target small cell, in block  2708 , the communication module  2041  (e.g., RRC layer) or other device may receive the RRC connection reconfiguration complete message from the UE  201 . Alternatively, the communication module  2041  (e.g., RRC layer) or other device may receive, from the MeNB  202 , the SeNB switch complete message or the small cell switch complete message (not illustrated in  FIG. 27 ), either of which may inform that the DRB has been successfully switched from the source small cell to the target small cell. When the UE  201  can access the target small cell, based on the S1 approach, the communication module  2041  or other device may receive/transmit packet data from/to the UE  201 , in block  2709 . 
     In some embodiments, in block  2710 , the communication module  2041  or other device may further transmit the path switch request to the MME  214  to request switching the downlink path of the EPS bearer from between the source SeNB  2030  and the core network system  204  to between the target SeNB  2040  and the core network system  204 , wherein the DRB of the EPS bearer has already been switched from the source SeNB  2030  to the target SeNB  2040 . The path switch request may include a list of the EPS bearer(s) whose DRB(s) has been switched. In some embodiments, the path switch request may further indicate to keep other bearer(s) unreleased, wherein the other bearer(s) may include those not listed in the request, such as the DRBs and/or the SRBs related to the MeNB  202 . Alternatively, the target SeNB  2040  or the MeNB  202  may send a separate request of keeping the other bearer(s) unreleased to the MME  214 . In other embodiments, it may be the MeNB  202  rather than the target SeNB  2040  which may send the path switch request to the MME  214 . 
     With modification of the downlink path of the EPS bearer to go through the target SeNB  2040 , the target SeNB  2040  may be able to receive the packet data from the core network system  204 , such as the S-GW  224 . In this way, the communication path between the UE  201  and the core network system  204  through the target SeNB  2040  has been completed. Further, the communication module  2041  or other device may receive the acknowledgement message, such as the patch switch request ACK from the MME  214 , in block  2711 . In block  2712 , the communication module  2041  or other device may receive the End Marker from the source SeNB  2030  indicating the end of data forwarding from the source SeNB  2030  to the target SeNB  2040 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 27 . For example, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB release request or the small cell release request may be sent from the source SeNB  2030  to MeNB  202  as well as to the target SeNB  2040 . Further, the SeNB release ACK or the small cell release ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 28  illustrates an embodiment of a method for the target SeNB  2040  of the wireless communication system  200  to switch the SeNB resources or the small cell by switching the bearer from the source SeNB  2030  to the target SeNB  2040 , based on the X2 approach. 
     In some embodiments, the method of  FIG. 28  may be similar as that of  FIG. 27 . For example, blocks  2801  to  2803  and blocks  2804 - 2805  may be similar as blocks  2701  to  2703 , and blocks  2707  to  2708 . However, due to the X2 approach, before switching the DRB of the EPS bearer from the source SeNB  2030  to the target SeNB  2040 , the source SeNB  2030  may communicate the packet data with the core network system  204  through the MeNB  202 . Moreover, in some embodiments, after the completion of the RRC connection reconfiguration to switch the DRB from the source SeNB  2030  to the target SeNB  2040 , the transmissions of the packet data between the target SeNB  2040  and the core network system  204  over the EPS bearer may still need to go through the MeNB  202 . In this way, there may be no need to forward the buffer and in transit packet data from the source SeNB  2030  to the target SeNB  2040 , or to request the core network system  204  to modify the downlink path of the EPS bearer from the SeNB  2030  to the target SeNB  2040 . In other words, the blocks  2704 - 2706  and blocks  2710 - 2712  of  FIG. 27  may be omitted from the  FIG. 28 . 
     Other embodiments may implement other modifications and variations to on the method as depicted in  FIG. 28 . For example, it may be the source SeNB  2030  rather than the MeNB  202  which makes the decision of switching the SeNB resources or the small cell. In such case, the SeNB release request or the small cell release request may be sent from the source SeNB  2030  to MeNB  202  as well as to the target SeNB  2040 , and the SeNB release ACK or the small cell release ACK may be sent from the MeNB  202  and the target SeNB  2040  to the source SeNB  2030 . 
       FIG. 29  schematically illustrates an example system  2900  in accordance with various embodiments. The system  2900  may comprise one or more processor(s)  2904 , system control logic  2908  coupled with at least one of the processor(s)  2904 , system memory  2912  coupled with system control logic  2908 , non-volatile memory (NVM)/storage  2916  coupled with system control logic  2908 , and a network interface  2920  coupled with system control logic  2908 . 
     Processor(s)  2904  may include one or more single-core or multi-core processors. Processor(s)  2904  may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, baseband processors, etc.). In an embodiment in which the system  2900  implements the UE  201 , processors(s)  2904  may be configured to execute one or more embodiment(s) as illustrated in  FIG. 2-4, 6-8, 13-15 , or  20 - 22  in accordance with various embodiments. In an embodiment in which the system  2900  implements the MeNB  202 , processor(s)  2904  may be configured to execute one or more embodiment(s) as illustrated in  FIG. 2-3, 5-7, 9-10, 13-14, 16-17, 20-21 , or  23 - 24  in accordance with various embodiments. In an embodiment in which the system  2900  implements the SeNB  203 , processor(s)  2904  may be configured to execute one or more embodiment(s) as illustrated in  FIG. 2, 6-7, 11-14 , or  18 - 19  in accordance with various embodiments. In an embodiment in which the system  2900  implements the source SeNB  2030 , processor(s)  2904  may be configured to execute one or more embodiment(s) as illustrated in  FIG. 2, 20-21 or 25-26  in accordance with various embodiments. In an embodiment in which the system  2900  implements the target SeNB  2040 , processor(s)  2904  may be configured to execute one or more embodiment(s) as illustrated in  FIG. 2, 20-21 or 27-28  in accordance with various embodiments. 
     System control logic  2908  for one embodiment may include any suitable interface controllers to provide for any suitable interface to at least one of the processor(s)  2904  and/or to any suitable device or component in communication with system control logic  2908 . 
     System control logic  2908  for one embodiment may include one or more memory controller(s) to provide an interface to system memory  2912 . System memory  2912  may be used to load and store data and/or instructions, for example, for system  2900 . System memory  2912  for one embodiment may include any suitable volatile memory, such as suitable dynamic random access memory (DRAM), for example. 
     NVM/storage  2916  may include one or more tangible, non-transitory computer-readable media used to store data and/or instructions, for example. NVM/storage  2916  may include any suitable non-volatile memory, such as flash memory, for example, and/or may include any suitable non-volatile storage device(s), such as one or more hard disk drive(s) (HDD(s)), one or more compact disk (CD) drive(s), and/or one or more digital versatile disk (DVD) drive(s), for example. 
     The NVM/storage  2916  may include a storage resource physically part of a device on which the system  2900  is installed or it may be accessible by, but not necessarily a part of, the device. For example, the NVM/storage  2916  may be accessed over a network via the network interface  2920 . 
     System memory  2912  and NVM/storage  2916  may respectively include, in particular, temporal and persistent copies of instructions  2924 . Instructions  2924  may include instructions that when executed by at least one of the processor(s)  2904  result in the system  2900  implementing one or more of method(s) as described with reference to  FIGS. 4-5, 8-12, 15-19, and 22-28 . In various embodiments, instructions  2924 , or hardware, firmware, and/or software components thereof, may additionally/alternatively be located in the system control logic  2908 , the network interface  2920 , and/or the processor(s)  2904 . 
     Network interface  2920  may have a transceiver (e.g., the communication module  211 ,  212  or  213  in  FIG. 2 , and the communication module  2031  or  2041  in  FIGS. 20-21 ) to provide a radio interface for system  2900  to communicate over one or more network(s) and/or with any other suitable device. In various embodiments, the communication module  211 ,  212  or  213  may be integrated with other components of system  2900 . For example, the communication module  211 ,  212 ,  213 ,  2031  or  2041  may include a processor of the processor(s)  2904 , memory of the system memory  2912 , NVM/Storage of NVM/Storage  2916 , and/or a firmware device (not being illustrated) having instructions that when executed by at least one of the processor(s)  2904  result in the system  2900  implementing one or more of method(s) as described with reference to  FIGS. 4-5, 8-12, 15-19, and 22-28 . 
     Network interface  2920  may include any suitable hardware and/or firmware. Network interface  2920  may include a plurality of antennas to provide a multiple input, multiple output radio interface. Network interface  2920  for one embodiment may include, for example, a network adapter, a wireless network adapter, a telephone modem, and/or a wireless modem. 
     For one embodiment, at least one of the processor(s)  2904  may be packaged together with logic for one or more controller(s) of system control logic  2908 . For one embodiment, at least one of the processor(s)  2904  may be packaged together with logic for one or more controllers of system control logic  2908  to form a System in Package (SiP). For one embodiment, at least one of the processor(s)  2904  may be integrated on the same die with logic for one or more controller(s) of system control logic  2908 . For one embodiment, at least one of the processor(s)  2904  may be integrated on the same die with logic for one or more controller(s) of system control logic  2908  to form a System on Chip (SoC). 
     The system  2900  may further include input/output (I/O) devices  2932 . The I/O devices  2932  may include user interfaces designed to enable user interaction with the system  2900 , peripheral component interfaces designed to enable peripheral component interaction with the system  2900 , and/or sensors designed to determine environmental conditions and/or location information related to the system  2900 . 
     In various embodiments, the user interfaces could include, but are not limited to, a display (e.g., a liquid crystal display, a touch screen display, etc.), a speaker, a microphone, one or more cameras (e.g., a still camera and/or a video camera), a flashlight (e.g., a light emitting diode flash), and a keyboard. 
     In various embodiments, the peripheral component interfaces may include, but are not limited to, a non-volatile memory port, an audio jack, and a power supply interface. 
     In various embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the network interface  2920  to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. 
     In various embodiments, the system  2900  may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, a mobile phone, etc. In other embodiments, the system  2900  may be an eNB, such as, but not limited to, a master eNB, a secondary eNB, etc. In various embodiments, system  2900  may have more or less components, and/or different architectures. 
     The disclosure may include various example embodiments disclosed below. 
     In example embodiment 1, a method, apparatus or system to be employed by a user equipment (UE) may comprise a communication module to communicate with a core network on a first bearer through a first evolved Node B (eNB), receive, from the first eNB, a first message of reconfiguring a radio resource control (RRC) connection to establish a second bearer between the UE and the core network through a second eNB; synchronize, in response to the message, with the second eNB in order to establish the second bearer; and communicate with the core network on the second bearer, and continue communicating other with the core network on the first bearer. 
     In example embodiment 2, the first eNB according to the example embodiment 1 may be a master eNB (MeNB). 
     In example embodiment 3, the second eNB according to any of the example embodiments 1-2 may be a secondary eNB (SeNB). 
     In example embodiment 4, the communication module according to any of the example embodiments 1-3 may further transmit, to the first eNB, a second message informing that the RRC connection reconfiguration has been completed. 
     In example embodiment 5, the first message according to any of the example embodiments 1-4 may comprise bearer context information related to the second bearer and eNB information related to the second eNB information. 
     In example embodiment 6, the first message according to any of the example embodiments 1-5 may comprise a new cell-radio network temporary identifier (C-RNTI), security algorithm identifiers, dedicated RACH preamble for a second cell associated to the second eNB, and/or others. 
     In example embodiment 7, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to communicate with a user equipment (UE) and a core network on a first bearer through the first eNB; receive, from the UE or the core network, a first request of establishing a second bearer between the UE and the core network; transmit, to a second eNB, a second request of adding the second eNB for the second bearer; and receive, from the second eNB, a response to the second request to acknowledge that the second eNB can be added for the second bearer. 
     In example embodiment 8, the first eNB according to the example embodiment 7 may be a master eNB (MeNB). 
     In example embodiment 9, the second eNB according to any of the example embodiments 7-8 may be a secondary eNB (SeNB). 
     In example embodiment 10, the second request according to any of the example embodiments 7-9 may be a SeNB addition request comprising a cause for the SeNB addition, a list of bearers to be setup, UE security capabilities, security context, and/or others. 
     In example embodiment 11, the response according to any of the example embodiments 7-10 may be a SeNB addition acknowledgment message comprising a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB addition, and/or others. 
     In example embodiment 12, the communication module according to any of the example embodiments 7-11 may further transmit, to or from the UE, a message of reconfiguring a radio resource control (RRC) connection to establish the second bearer, wherein the message includes bearer context information related to the second bearer and eNB information related to the second eNB. 
     In example embodiment 13, the message according to any of the example embodiments 7-12 may comprise a new cell-radio network temporary identifier (C-RNTI), security algorithm identifiers, dedicated random access channel (RACH) preamble for a second cell associated with the second eNB, and/or others. 
     In example embodiment 14, the communication module according to any of the example embodiments 7-13 may further receive, from the UE, another message informing that the RRC connection reconfiguration has been completed; and transmit, to the core network, another response to the first request to inform that the second bearer has been redirected to the second eNB. 
     In example embodiment 15, the first eNB according to any of the example embodiments 7-14 may continue communicating with the UE and the core network on the first bearer through the first cell, while the UE further communicates with the core network on the second bearer through the second eNB. 
     In example embodiment 16, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to receive, from a second eNB for a second cell, a request of adding the first eNB for a first bearer to be established between a user equipment (UE) and a core network; transmit, to the second eNB, a response to the first request to acknowledge that the first eNB can be added for the first bearer; synchronize with the UE in order to establish the first bearer; and communicate with the UE and the core network on the first bearer through the first eNB, wherein, the UE communicates with the core network on a second bearer through the second eNB. 
     In example embodiment 17, the first eNB according to the example embodiment 16 may be a secondary eNB (SeNB). 
     In example embodiment 18, the second eNB according to any of the example embodiments 16-17 may be a macro eNB (MeNB). 
     In example embodiment 19, the first request according to any of the example embodiments 16-18 may be a SeNB addition request comprising a cause for the SeNB addition, a list of bearers to be setup, UE security capabilities, security context, and/or others. 
     In example embodiment 20, the response according to any of the example embodiments 16-19 may be a SeNB addition acknowledgement message comprising a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for SeNB addition, and/or others. 
     In example embodiment 21, a method, apparatus or system to be employed by a user equipment (UE), may comprise a communication module to communicate with a core network on one or more data bearers through a first evolved Node B (eNB); receive, from the first eNB, a message of reconfiguring a radio resource control (RRC) connection to switch at least one of the one or more data bearers from the first eNB to a second eNB; synchronize with the second eNB, in response to the message; and communicate with the core network on the at least one of the data bearers through the second eNB, while communicating with the first eNB on a signaling bearer through the first eNB. 
     In example embodiment 22, the first eNB according to the example embodiment 21 may be a master eNB (MeNB). 
     In example embodiment 23, the second eNB according to any of the example embodiments 21-22 may be a secondary eNB (SeNB). 
     In example embodiment 24, the message according to any of the example embodiments 21-23 may be a RRCconnectionreconfiguration message comprising a new cell-radio network temporary identifier (C-RNTI), second eNB security algorithm identifiers and optionally dedicated random access channel (RACH) preamble, second eNB system information blocks, and/or others. 
     In example embodiment 25, the communication module according to any of the example embodiments 21-24 may further continue communicating with the core network on a remaining data bearer of the data bearers which hasn&#39;t been switched from the first eNB to the second eNB. 
     In example embodiment 26, the communication module according to any of the example embodiments 21-25 may further transmit, to the first eNB or the second eNB, another message informing that the RRC connection reconfiguration has been completed. 
     In example embodiment 27, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to communicate with a user equipment (UE) and a core network on one or more data bearers through the first eNB; transmit, to a second eNB, a first request of adding a second SeNB by switching at least one of the data bears from the first eNB to the second eNB; receive, from the second eNB, a first message to acknowledge that the second eNB can be added; transmit, to the UE, a second message of reconfiguring a radio resource control (RRC) connection to switch the at least one data bearer; and communicate with the UE on a signaling bearer through the first eNB, while the UE communicates with the core network on the at least one data bearer through the second eNB. 
     In example embodiment 28, the first eNB according to the example embodiment 27 may be a master eNB (MeNB). 
     In example embodiment 29, the second eNB according to any of the example embodiments 27-28 may be a secondary eNB (SeNB). 
     In example embodiment 30, the communication module according to any of the example embodiments 27-29 may further continue communicating with the UE and the core network on a remaining data bear of the data bears which hasn&#39;t been switched from the first eNB to the second eNB. 
     In example embodiment 31, the communication module according to any of the example embodiments 27-30 may further receive, from the UE, a third message informing that the RRC connection reconfiguration has been completed. 
     In example embodiment 32, the communication module according to any of the example embodiments 27-31 may further transmit, to the second eNB, a fourth message informing that the second SeNB has been added. 
     In example embodiment 33, the communication module according to any of the example embodiments 27-32 may further transmit, to the core network, a second request of switching a downlink path of an evolved packet system (EPS) bearer from between the first eNB and the core network to between the second eNB and the core network, wherein a data bearer of the EPS bearer has been switched from the first eNB to the second eNB. 
     In example embodiment 34, the communication module according to any of the example embodiments 27-33 may further transmit, to the core network, an indication to keep at least one EPB bearer not listed in the second request unreleased. 
     In example embodiment 35, the first request according to any of the example embodiments 27-34 may be a SeNB addition request comprising cause for a list of bearers to be setup, UE security capabilities, security context, and/or others. 
     In example embodiment 36, the first message according to any of the example embodiments 27-35 may be a SeNB addition acknowledgement message comprising a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB addition, and/or others. 
     In example embodiment 37, the communication module according to any of the example embodiments 27-36 may further receive, from the UE, a measurement report about UE connection mobility; and determine, based on the measurement report, to add the second SeNB. 
     In example embodiment 38, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to receive, from a second eNB, a first request of adding the first eNB by switching at least one of one or more data bearers from the second eNB to the first eNB, wherein a user equipment (UE) communicated with a core network on the data bears through the second eNB; transmit, to the second eNB, a first message to acknowledge that the first eNB can be added; synchronize with the UE in order to establishing the at least one data bearer between the UE and the second eNB; communicate with the UE and the core network on the at least one data bearer through the first eNB, while the UE communicates with the second eNB on a signalling bearer through second eNB. 
     In example embodiment 39, the first eNB according to the example embodiment 38 may be a secondary eNB (MeNB). 
     In example embodiment 40, the second eNB according to any of the example embodiments 38-39 may be a master eNB (SeNB). 
     In example embodiment 41, the UE according to any of the example embodiments 38-40 may continue communicating with the core network on a remaining data bear of the data bearers which hasn&#39;t been switched from the second eNB to the first eNB. 
     In example embodiment 42, the communication module according to any of the example embodiments 38-41 may further transmit, to the core network, a second request of switching a downlink data path of the at least one data bearer from between the second eNB and the core network to between the first eNB and the core network; receive, from the core network, a second message to acknowledge that the downlink data path of the at least one data bearer has been switched. 
     In example embodiment 43, the communication module according to any of the example embodiments 38-42 may further transmit, to the core network, an indication of keeping a remaining data bearer of the data bearers, which hasn&#39;t been switched from the second eNB to the first eNB, unreleased. 
     In example embodiment 44, the first request according to any of the example embodiments 38-43 may be a SeNB addition request comprising cause for a list of bearers to be setup, UE security capabilities, security context, and/or others. 
     In example embodiment 45, the first message according to any of the example embodiments 38-44 may be a SeNB addition acknowledgement message comprising a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB addition, and/or others. 
     In example embodiment 46, a method, apparatus, or system to be employed by a user equipment (UE), may comprise a communication module to communicate with a first evolved Node B (eNB) on a first bearer through the first eNB; communicate with a second eNB on a second bearer through a second eNB; receive, from the second eNB, a first message of reconfiguring a radio resource control (RRC) connection to switch the first bearer from the first eNB to the second eNB; detach from the first eNB, in response to the first message; communicate on the first bear through the second eNB, while continuing communicating on the second bearer through the second eNB. 
     In example embodiment 47, the first eNB according to the example embodiment 46 may be a secondary eNB (MeNB). 
     In example embodiment 48, the second eNB according to any of the example embodiments 46-47 may be a master eNB (SeNB). 
     In example embodiment 49, the first message according to any of the example embodiments 46-48 may be a RRCconnectionreconfiguration message comprising a SeNB release information to inform the UE that the second SeNB is going to be released. 
     In example embodiment 50, the communication module according to any of the example embodiments 46-49 may further transmit, to the second eNB, a second message informing that the RRC connection reconfiguration is completed. 
     In example embodiment 51, a method, apparatus or system to be employed by a first evolved node B (eNB), may comprise a communication module to communicate with a user equipment (UE) on a first bearer through the first eNB, while the UE communicates with a second eNB on a second bearer through the second eNB; transmit or receive, to or from a second eNB, a first request of releasing the second eNB; receive or transmit, from or to the second eNB, a first message to acknowledge that the second eNB can be released; and transmit, to the UE, a second message of reconfiguring a radio resource control (RRC) connection to switch the second bearer from the second eNB to the first eNB. 
     In example embodiment 52, the first eNB according to the example embodiment 51 may be a macro eNB (MeNB). 
     In example embodiment 53, the second eNB according to any of the example embodiments 51-52 may be a secondary eNB (SeNB). 
     In example embodiment 54, the first request according to any of the example embodiments 51-53 may be a SeNB release request including at least one of a cause for the SeNB release, a list of bearers to be switched, a UE cell-radio network temporary identifier (C-RNTI) in a second cell associated with the second eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 55, the first message according to any of the example embodiments 51-54 may be a SeNB release acknowledgment message including at least one of a UE cell-radio network temporary identifier (C-RNTI), a cause for the SeNB release, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the cell release, and/or others. 
     In example embodiment 56, the first bearer according to any of the example embodiments 51-55 may be a signalling bearer and/or a data bearer, and the second bearer is a data bearer. 
     In example embodiment 57, the communication module according to any of the example embodiments 51-56 may further receive, from the UE, a third message informing that the RRC connection reconfiguration is completed; and transmit, to the second eNB, a fourth message informing that the second bearer has been released. 
     In example embodiment 58, the communication module according to any of the example embodiments 51-57 may further transmit, to a core network, a second request of switching a downlink path of the second bearer from between the second eNB and the core network to between the first eNB and the core network, wherein the second request further indicates not to release a bearer associated with the UE and not listed in the second request. 
     In example embodiment 59, the communication module according to any of the example embodiments 51-58 may further receive, from the core network, a fifth message to acknowledge that the downlink data path of the second bearer is switched. 
     In example embodiment 60, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to communicate with a user equipment (UE) on a first bearer through the first eNB, wherein the UE further communicates on a second bearer through a second eNB; receive or transmit, from or to a second eNB, a first request of releasing the first SeNB by switching the first bearer from the first eNB to the second eNB; transmit or receive, to or from the second eNB, a first message to acknowledge that the first SeNB can be released in response to a determination that the first request is acceptable; and detach from the UE in order to release the first bearer. 
     In example embodiment 61, the first eNB according to the example embodiment 60 may be a secondary eNB (MeNB). 
     In example embodiment 62, the second eNB according to any of the example embodiments 60-61 may be a master eNB (SeNB). 
     In example embodiment 63, the first request according to any of the example embodiments 60-62 may be a SeNB release request including at least one of a cause for the SeNB release or the small cell release, a list of bearers to be switched, a UE cell-radio network temporary identifier (C-RNTI) in a second cell associated with the second eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 63, the first message according to any of the example embodiments 60-62 may be a SeNB release acknowledgment message including at least one of a UE cell-radio network temporary identifier (C-RNTI), a cause for the SeNB release, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB release, and/or others. 
     In example embodiment 64, the communication module according to any of the example embodiments 60-63 may further transmit, to a core network, a second request of switching a downlink path of the first bearer from between the first eNB and the core network to between the second eNB and the core network, wherein the second request further indicates not to release a bearer associated with the UE and not listed in the second request. 
     In example embodiment 65, the communication module according to any of the example embodiments 60-64 may further receive, from the core network, a second message to acknowledge that the downlink data path of the first bearer is switched. 
     In example embodiment 66, a method, apparatus, or system to be employed by a user equipment (UE), may comprise a communication module to communicate with a first evolved Node B (eNB) on a first bearer through a first eNB; communicate with a second eNB on a second bearer through a second eNB; receive, from the first eNB, a first message of reconfiguring a radio resource control (RRC) connection to switch the second bearer from the second eNB to a third eNB; detach from the second eNB and synchronizing with the third eNB, in response to the first message; communicate with the third eNB on the second bearer through the third eNB, while continuing communicating with the first eNB on the first bearer through the first eNB. 
     In example embodiment 67, the first eNB according to the example embodiments 66 may be a master eNB (MeNB). 
     In example embodiment 68, the second eNB according to any of the example embodiments 66-67 may be a source secondary eNB (SeNB). 
     In example embodiment 69, the third eNB according to any of the example embodiments 66-68 may be a target secondary eNB (SeNB). 
     In example embodiment 70, the first message according to any of the example embodiments 66-69 may be a RRCconnectionreconfiguration message comprising at least one of second eNB information, third eNB information and others. 
     In example embodiment 71, the communication module according to any of the example embodiments 66-70 may further transmit, to the first eNB or the third eNB, a second message informing that the RRC connection reconfiguration is completed. 
     In example embodiment 72, the first bearer according to any of the example embodiments 66-71 may be a data bearer and/or a signalling bearer, and the second bearer is another data bearer. 
     In example embodiment 73, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to communicate with a user equipment (UE) on a first bearer through the first eNB, wherein the UE further communicates with a second eNB on a second bearer through the second eNB; transmit or receive, to or from a second eNB, a first request of switching the second eNB by switching the second bearer from the second eNB to a third eNB; and receive or transmit, from or to the second eNB, a first message to acknowledge that the second eNB can be switched. 
     In example embodiment 74, the first eNB according to the example embodiment 73 may be a master eNB (MeNB). 
     In example embodiment 75, the second eNB according to any of the example embodiments 73-74 may be a source secondary eNB (SeNB). 
     In example embodiment 76, the third eNB according to any of the example embodiments 73-75 may be a target secondary eNB (SeNB). 
     In example embodiment 77, the first request according to any of the example embodiments 73-76 may be a SeNB switch request including at least one of a TYPE field indicating whether an eNB receiving the first request adds the second bearer or release the second bearer, a cause for the SeNB switch, a list of bearers to be setup or released, a UE cell-radio network temporary identifier (C-RNTI) in a second cell associated with the second eNB or a third cell associated with the third eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 78, the first message according to any of the example embodiments 73-77 may be a SeNB switch request acknowledgement message comprising at least one of cell-radio network temporary identifier (C-RNTI), a cause for the SeNB switch, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB switch, and/or others. 
     In example embodiment 79, the communication module according to any of the example embodiments 73-78 may further transmit, to the third eNB, a second request of switching the second eNB by switching the second bearer from the second cell to the third cell; and receive, from the third eNB, a second message to acknowledge that the second eNB can be switched. 
     In example embodiment 80, the second request according to any of the example embodiments 73-79 may be a SeNB switch request comprising at least one of a TYPE field indicating whether an eNB receiving the message adds the second bearer or release the second bearer, a cause for the small cell switch, a list of bearers to be setup or released, a UE cell-radio network temporary identifier (C-RNTI) in a second cell associated with the second eNB or a third cell associated with the third eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 81, the second message according to any of the example embodiments 73-80 may be a SeNB switch acknowledgement message comprising at least one of a cell-radio network temporary identifier (C-RNTI), a cause for the SeNB switch, a list of admitted bearers, a list of unadmitted bearers, a transparent container to be sent to the UE for SeNB switch, and/or others. 
     In example embodiment 82, the communication module according to any of the example embodiments 73-81 may further transmit, to the UE, a third message of reconfiguring a radio resource control (RRC) connection by switching the second bearer from the second eNB to the third eNB. 
     In example embodiment 83, the third message according to any of the example embodiments 73-82 may be a RRCconnectionreconfiguration message comprising at least one of second Enb information, third eNB information and/or others. 
     In example embodiment 84, the communication module according to any of the example embodiments 73-83 may further receive, from the UE, a fourth message informing that the RRC connection reconfiguration is completed; and transmit, to the second eNB and/or the third eNB, a fifth message informing that the second eNB switch is completed. 
     In example embodiment 85, the communication module according to any of the example embodiments 73-84 may further transmit, to the second eNB, a third request of transferring a sequence number (SN) status from the second eNB to the third eNB. 
     In example embodiment 86, the communication module according to any of the example embodiments 73-85 may further transmit, to a core network, a fourth request of switching a downlink path of the second bearer from between the second eNB and the core network to between the third eNB and the core network. 
     In example embodiment 87, the fourth request according to any of the example embodiments 73-86 may further indicate not to release a bearer associated with the UE and not listed in the second request. 
     In example embodiment 88, the communication module according to any of the example embodiments 73-87 may further continue communicating with the UE on the first bearer through the first eNB, while the UE further communicates with the third eNB on the second bearer through the second eNB. 
     In example embodiment 89, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to communicate with a user equipment on a first bearer through the first eNB, wherein the UE further communicates with a second eNB on a second bearer through the second eNB; receive or transmit, from or to the second eNB, a first request of switching the first eNB by switching the first bearer from the first eNB to a third eNB; and transmit or receive, to or from the second eNB, a first message to acknowledge that the first eNB can be switched. 
     In example embodiment 90, the first eNB according to the example embodiments 89 may be a source secondary eNB (SeNB). 
     In example embodiment 91, the second eNB according to any of the example embodiments 89-90 may be a master eNB (MeNB). 
     In example embodiment 92, the third eNB according to any of the example embodiments 89-91 may be a target secondary eNB (SeNB). 
     In example embodiment 93, the first request according to any of the example embodiments 89-92 may be a SeNB switch request comprising at least one of a TYPE field indicating whether an eNB receiving the message adds the first bearer or release the first bearer, a cause for the SeNB switch, a list of bearers to be setup or released, a UE cell-radio network temporary identifier (C-RNTI) in a first cell associated with the first eNB or a third cell associate with the third eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 94, the first message according to any of the example embodiments 89-93 may be a SeNB switch request acknowledgement message comprising at least one of cell-radio network temporary identifier (C-RNTI), a cause for the SeNB switch, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB switch, and/or others. 
     In example embodiment 95, the communication module according to any of the example embodiments 89-94 may further receive, from the second eNB, a second message of transferring a sequence number (SN) status from the first eNB to the third eNB; and forward, in response to the second message, a buffered and in transit data to the third eNB. 
     In example embodiment 96, the communication module according to any of the example embodiments 89-95 may further transmit, to a core network, a third request of switching a downlink path of the first bearer from between the first eNB and the core network to between the third eNB and the core network. 
     In example embodiment 97, the third request according to any of the example embodiments 89-96 may further indicate not to release a bearer associated with the UE and not listed in the third request. 
     In example embodiment 98, a method, apparatus or system to be employed by a first evolved Node B (eNB), may comprise a communication module to communicate with a user equipment on a first bearer through the first eNB, wherein the UE further communicates with a second eNB on a second bearer through the second eNB; transmit, to a third eNB, a first request of switching the first eNB by switching the first bearer from the first eNB to the third eNB; and receive, from the third eNB, a first message to acknowledge that the first eNB can be switched. 
     In example embodiment 99, the first eNB according to the example embodiments 98 may be a source secondary eNB (SeNB). 
     In example embodiment 100, the second eNB according to any of the example embodiments 98-99 may be a master eNB (MeNB). 
     In example embodiment 101, the third eNB according to any of the example embodiments 98-100 may be a target secondary eNB (SeNB). 
     In example embodiment 102, the first request according to any of the example embodiments 98-101 may be a SeNB switch request comprising at least one of a TYPE field indicating whether an eNB receiving the message adds the first bearer or release the first bearer, a cause for the SeNB switch, a list of bearers to be setup or released, a UE cell-radio network temporary identifier (C-RNTI) in a first cell associated with the first eNB or a third cell associated with the third eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 103, the first message according to any of the example embodiments 98-102 may be a SeNB switch request acknowledgement message comprising at least one of cell-radio network temporary identifier (C-RNTI), a cause for the SeNB switch, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB switch, and/or others. 
     In example embodiment 104, the communication module according to any of the example embodiments 98-103 may further transmit, to the second eNB, a second request of switching the first eNB by switching the first bearer from the first eNB to the third eNB; and receive, from the second eNB, a second message to acknowledge that the first eNB can be switched. 
     In example embodiment 105, the second request according to any of the example embodiments 98-104 may be a SeNB switch request comprising at least one of a TYPE field indicating whether an eNB receiving the message adds the first bearer or release the first bearer, a cause for the SeNB switch, a list of bearers to be setup or released, a UE cell-radio network temporary identifier (C-RNTI) in the second cell or the third cell, UE security capabilities, security context, and/or others. 
     In example embodiment 106, the second message according to any of the example embodiments 98-105 may be a small cell switch request acknowledgement message comprising at least one of cell-radio network temporary identifier (C-RNTI), a cause for the cell switch, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the small cell switch, and/or others. 
     In example embodiment 107, the communication module according to any of the example embodiments 98-106 may further receive, from the second eNB, a third message of transferring a sequence number (SN) status from the first eNB to the third eNB; and forward, in response to the third message, a buffered and in transit data to the third eNB. 
     In example embodiment 108, the communication module according to any of the example embodiments 98-101 may further transmit, to a core network, a third request of switching a downlink path of the first bearer from between the first eNB and the core network to between the third eNB and the core network. 
     In example embodiment 109, the third request according to any of the example embodiments 98-108 may further indicate not to release a bearer associated with the UE and not listed in the third request. 
     In example embodiment 110, a method, apparatus or system to be employed by a first eNB, may comprise a communication module to receive, from a second eNB or a third eNB, a first request of switching a third eNB by switching a first bearer from the third eNB to the first eNB, wherein a user equipment (UE) communicates with the third eNB on the first bearer through the third eNB and communicates with the second eNB on a second bearer through the second eNB; transmit, to the second eNB or the third eNB, a first message to acknowledge that the third eNB can be switched; synchronize with the user equipment (UE) to establish the first bearer through the first eNB; and communicate with the UE on the first bearer through the first eNB. 
     In example embodiment 111, the first eNB according to the example embodiment 110 may be a target secondary eNB (SeNB). 
     In example embodiment 112, the second eNB according to any of the example embodiments 110-111 may be a master eNB (MeNB). 
     In example embodiment 113, the third eNB according to any of the example embodiments 110-112 may be a source secondary eNB (SeNB). 
     In example embodiment 114, the first request according to any of the example embodiments 110-113 may be a SeNB switch request comprising at least one of a TYPE field indicating whether an eNB receiving the message adds the first bearer or release the first bearer, a cause for the SeNB switch, a list of bearers to be setup or released, a UE cell-radio network temporary identifier (C-RNTI) in a first cell associated with the first eNB or a third cell associated with the third eNB, UE security capabilities, security context, and/or others. 
     In example embodiment 115, the first message according to any of the example embodiments 110-114 may be a SeNB switch request acknowledgement message comprising at least one of cell-radio network temporary identifier (C-RNTI), a cause for the SeNB switch, a list of admitted bearers, a list of not admitted bearers, a transparent container to be sent to the UE for the SeNB switch, and/or others. 
     In example embodiment 116, the communication module according to any of the example embodiments 110-115 may further transmit, to a core network, a second request of switching a downlink path of the first bearer from between the third eNB and the core network to between the first eNB and the core network. 
     In example embodiment 117, the third request according to any of the example embodiments 110-116 may further indicate not to release a bearer associated with the UE and not listed in the second request. 
     Although certain embodiments have been illustrated and described herein for purposes of description, a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments described herein be limited only by the claims and the equivalents thereof.

Metadata:
Filing Date: 20171106
Publication Date: 20201215
Grant Date: 20201215
Priority Date: 20130117
Inventors: ZHANG, YUJIAN
PINHEIRO, ANA LUCIA A.
HEO, YOUN HYOUNG
YIU, Candy
FONG, MO-HAN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W48/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/0431", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/0035", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L5/0076", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L1/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L9/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W52/0251", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/1469", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W76/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0055", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0092", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W68/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W48/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L63/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/28", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L5/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W84/045", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L5/0096", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L2209/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W12/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W88/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W88/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W74/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L2209/24", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/4076", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/1278", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/1263", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0062", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/0413", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0055", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0035", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L65/602", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W72/046", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0092", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/11", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/0066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0051", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/04031", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W52/0251", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W4/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02B70/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B7/0456", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/0417", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L63/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W56/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L9/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W16/32", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W84/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/1887", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0094", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L2209/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/042", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04J3/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/1469", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/608", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/1812", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W28/0231", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/1006", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W88/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W68/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0096", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0057", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L65/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/0406", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W24/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L43/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/1205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/08", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L63/0428", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00692", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00692", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00692", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/0035", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W76/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/11", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W76/27", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/0069", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D30/70", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W12/0431", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W12/50", "inventive": false, "f
Family ID: 91081891