Abstract:
One embodiment is directed to a method comprising receiving and storing a set of cellular network and unlicensed frequency network interworking parameters from a cellular source cell; offloading data traffic from the cellular source cell to an unlicensed frequency network based on the stored set of interworking parameters; receiving a handover command including a second set of cellular network and unlicensed frequency network interworking parameters; checking whether information regarding unlicensed frequency network has been received from a cellular target cell; and if the information regarding unlicensed frequency network has not been received, determining whether to use the second set of cellular network and unlicensed frequency network interworking parameters after the handover.

Description:
RELATED APPLICATIONS 
       [0001]    This application relates to, and claims the benefit of U.S. Application filing No. 62/039,881, entitled, “Apparatus and method for interworking optimization in connection with cellular handover”, filed on Aug. 20, 2014, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present application relates generally to an apparatus and a method for interworking optimization in connection with cellular handover. 
       BACKGROUND 
       [0003]    This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application. 
         [0004]    As the number of wireless cellular data communication devices continues to increase and as their data capabilities continue to be more and more heavily used, the usage on the available frequencies dedicated to cellular data communication comes closer and closer to saturation. One approach to the management of traffic load is the offloading of traffic onto unlicensed frequencies, such as those used by wireless local area networks, WLAN, whose presence may be represented by one or more access points, APs. Network operators may implement wireless network infrastructure, which uses unlicensed frequencies, and manage the transfer of traffic between base stations using licensed frequencies and unlicensed network access points. Such an approach may be used, for example, by 3rd Generation Partnership Project, 3GPP, long term evolution, LTE or LTE-advanced, LTE-A, networks. The efficient use of unlicensed frequencies and the efficient transfer of traffic between licensed frequencies and access points using unlicensed frequencies has the potential to greatly increase wireless data capacity. 
       SUMMARY 
       [0005]    Various aspects of examples of the invention are set out in the claims. 
         [0006]    According to a first aspect of the present invention, a method may include receiving and storing a set of cellular network and unlicensed frequency network interworking parameters from a cellular source cell; offloading data traffic from the cellular source cell to an unlicensed frequency network based on the stored set of interworking parameters; receiving a handover command including a second set of cellular network and unlicensed frequency network interworking parameters; checking whether information regarding unlicensed frequency network has been received from a cellular target cell; and if the information regarding unlicensed frequency network has not been received, determining whether to use the second set of cellular network and unlicensed frequency network interworking parameters after the handover. 
         [0007]    According to a second aspect of the present invention, an apparatus may include at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to receive and store a set of cellular network and unlicensed frequency network interworking parameters from a cellular source cell; offload data traffic from the cellular source cell to an unlicensed frequency network based on the stored set of interworking parameters; receive a handover command including a second set of cellular network and unlicensed frequency network interworking parameters; check whether information regarding unlicensed frequency network has been received from a cellular target cell; and if the information regarding unlicensed frequency network has not been received, determine whether to use the second set of cellular network and unlicensed frequency network interworking parameters after the handover. 
         [0008]    According to a third aspect of the present invention, a computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code may include code for receiving and storing a set of cellular network and unlicensed frequency network interworking parameters from a cellular source cell; code for offloading data traffic from the cellular source cell to an unlicensed frequency network based on the stored set of interworking parameters; code for receiving a handover command including a second set of cellular network and unlicensed frequency network interworking parameters; code for checking whether information regarding unlicensed frequency network has been received from a cellular target cell; and code for if the information regarding unlicensed frequency network has not been received, determining whether to use the second set of cellular network and unlicensed frequency network interworking parameters after the handover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    For a more complete understanding of example embodiments of the present invention, reference is now made to the following descriptions taken in connection with the accompanying drawings in which: 
           [0010]      FIG. 1  illustrates an example wireless system in accordance with an example embodiment of the application. 
           [0011]      FIG. 2  illustrates an example of signaling utilized by a user equipment and a network in accordance with an example embodiment of the application. 
           [0012]      FIG. 3  illustrates another example of signaling utilized by a user equipment and a network in accordance with an example embodiment of the application. 
           [0013]      FIG. 4  illustrates another example of signaling utilized by a user equipment and a network in accordance with an example embodiment of the application. 
           [0014]      FIG. 5  illustrates a simplified block diagram of various example apparatuses that are suitable for use in practicing various example embodiments of this application. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]      FIG. 1  illustrates an example wireless system  100  in accordance with an example embodiment of the application. The example wireless system  100  comprises a 3 rd  generation partnership project, 3GPP, evolved NodeB, eNB,  101  connecting to a core network that is not shown for brevity, and an unlicensed network such as for example, wireless local area networks, WLAN, access point, AP,  103 . The macro cell eNB  101  is configured to communicate with one or more user equipment, UEs  105  and  107 . The WLAN AP  103  may be configured to connect with the macro cell eNB  101  via a wireless link, and is configured to provide wireless connections in the WLAN local area  110  to devices, such as for example the UE  105 , in order to offload traffic from eNB  101 . Although just one macro cell eNB, one WLAN AP and two UEs are shown in  FIG. 1 , the example wireless system  100  may comprise more or less eNBs, WLAN APs and UEs. 
         [0016]    The WLAN/3GPP radio interworking, IW, has been extensively discussed and the signaling of WLAN offloading configuration has already been specified. The configuration of thresholds for WLAN offloading parameters, including reference signal received power, RSRP, reference signal received quality, RSRQ, channel utilization, backhaul downlink/uplink bandwidth, etc., can be signaled in system information, such as for example, SIB 17. The configuration can also be included in dedicated signaling, i.e. radio resource control, RRC, connection reconfiguration message. On the other hand, the configuration of WLAN identifiers and the corresponding WLAN priorities are signaled in system information. 
         [0017]    In the case of handover, HO, it is possible that the dedicated configuration of the thresholds for WLAN offloading parameters is signaled via a handover command, i.e. the RRC connection reconfiguration message including mobility control information. Upon receiving the handover command, the UE may apply the dedicated thresholds for WLAN offloading parameters included in the handover command, and initiates a handover to the target cell. Handover is considered successful if the UE completes the random access procedure in the target cell. After handover complete, the UE acquires system information and applies the configuration of WLAN identifiers and WLAN priorities included in system information of the target cell. Note that there is no clear requirements how long it can take for the UE to acquire system information, such as for example, SIB 17. If source and target cells are broadcasting different WLAN identifiers, the UE would potentially use not allowed WLAN. 
         [0018]    In an example embodiment, a UE may start using WLAN/3GPP IW parameters received in HO command, such as for example, RRC Connection reconfiguration message with mobility control info, only after (or at point of) receiving WLAN identifiers from SIB17 of the target cell. During the time UE has not yet received broadcast (but has received new WLAN/3GPP IW parameters in HO command), the UE may or may not continue using old WLAN/3GPP IW parameters received from source cell. In an alternative example embodiment, during the time UE has not yet received broadcast (but has received new WLAN/3GPP IW parameters in HO command), the UE shall or shall not continue using old WLAN/3GPP IW parameters received from source cell. 
         [0019]    In an example embodiment, information indicating whether same WLAN identifier received from the source cell can be used on the target cell is added to handover command. In an example embodiment, information indicating whether UE needs to acquire system information, such as for example, SIB 17, in the target cell may be sent to UE so that UE may continue using existing parameters if network indicates no need to acquire SIB 17. 
         [0020]    In an example embodiment, information indicating where a WLAN identifier can be used in 3GPP/WLAN interworking may be indicated to UE. The information can be such as for example, an indication showing that the WLAN identifier can be used only in the cell where the information was received; in cells from a list of cells; in a public land mobile network, PLMN; in certain carrier or frequency; in certain tracking area/routing area/location area; or during the time of validity, and so on. 
         [0021]    In an example embodiment, a WLAN identifier may be provided by dedicated signaling, such as for example, an HO command. 
         [0022]    It should be noted that if a UE is not supposed to use old WLAN identifiers in a new cell after HO, the UE may still use old information until new WLAN identifier is received (i.e., UE may continue WLAN offloading) or UE does not use old information and is or is not allowed to continue WLAN offloading. This could be configurable by network. 
         [0023]      FIG. 2  illustrates an example of signaling utilized by a UE and a network, NW, in accordance with an example embodiment of the application. In the example of  FIG. 2 , a UE  220 , such as for example, the UE  105  of  FIG. 1 , is camping on a cell  1  under eNB 1   221 , such as for example, the eNB  101  of  FIG. 1 . The UE  220  reads system information at step  201  from eNB  1   221  where in this example three WLAN identifiers A, B and C are included for radio access network, RAN, assisted 3GPP/WLAN interworking. In the example of  FIG. 2 , the UE is in coverage area of WLAN A, such as for example, the WLAN area  110  of  FIG. 1 . At step  202 , the NW transmits an RRCConnectionReconfiguration message on cell  1  to setup intra frequency measurement and to configure dedicated WLAN/3GPP interworking parameters. The UE transmits an RRCConnectionReconfigurationComplete message on cell  1  for confirmation at step  203 . Active data transmission starts between the UE and the network at step  204  after the RRC connection is reconfigured. If a criteria for starting the use of WLAN A is fulfilled, the UE can start to use WLAN A for data transmission at step  205 . 
         [0024]    When the UE  220  moves geographically and a neighbor cell  2  under eNB 2   222  becomes better than the serving cell  221  (i.e. criteria for measurement reporting is fulfilled), the UE may transmit a MeasurementReport message on cell  1  to report event at step  206 . If the NW determines that the UE should handover to cell  2 , the NW transmits an RRCConnectionReconfiguration message at step  207  to order the UE to perform the handover to cell  2 . The new dedicated WLAN/3GPP interworking parameters may be included in the RRCConnectionReconfiguration message sent at step  207 . At step  208 , the UE transmits an RRCConnectionReconfigurationComplete message on cell  2  for confirmation of the handover. At this moment, if the UE is allowed to use old WLAN/3GPP interworking parameters to continue the offloading, the UE may still use WLAN A for data transmission if it is still in coverage area of WLAN A. After the handover, the UE may read system information at step  209  from cell  2  where in this example WLAN identifiers B and C are included for RAN assisted WLAN/3GPP interworking. Then the UE stops using WLAN A for data transmission at step  210  in this example, and may start to use WLAN B or C for offloading with the new dedicated WLAN/3GPP interworking parameters at step  211   
         [0025]      FIG. 3  illustrates another example of signaling utilized by a UE and a network, NW, in accordance with an example embodiment of the application. In the example of  FIG. 3 , a UE  320 , such as for example, the UE  105  of  FIG. 1 , is camping on a cell  1  under eNB 1   321 , such as for example, the eNB  101  of  FIG. 1 . The UE  320  reads system information at step  301  from eNB 1   321  where in this example three WLAN identifiers A, B and C are included for RAN assisted 3GPP/WLAN interworking. In the example of  FIG. 3 , the UE is in coverage area of WLAN A, such as for example, the WLAN area  110  of  FIG. 1 . At step  302 , the NW transmits an RRCConnectionReconfiguration message on cell  1  to setup intra frequency measurement and to configure dedicated WLAN/3GPP interworking parameters. The UE transmits an RRCConnectionReconfigurationComplete message on cell  1  for confirmation at step  303 . Active data transmission starts between the UE and the network at step  304  after the RRC connection is reconfigured. If a criteria for starting the use of WLAN A is fulfilled, the UE can start to use WLAN A for data transmission at step  305 . 
         [0026]    When the UE  320  moves geographically and a neighbor cell  2  under eNB 2   322  becomes better than the serving cell  321  (i.e. criteria for measurement reporting is fulfilled), the UE may transmit a MeasurementReport message on cell  1  to report event at step  306 . If the NW determines that the UE should handover to cell  2 , the NW transmits an RRCConnectionReconfiguration message at step  307  to order the UE to perform the handover to cell  2 . The new dedicated WLAN/3GPP interworking parameters may be included in the RRCConnectionReconfiguration message sent at step  307 . In the example of  FIG. 3 , information (such as for example, a flag set to TRUE) indicating that same WLAN identifiers can be used is also included in the message sent at step  307 . At step  308 , the UE transmits an RRCConnectionReconfigurationComplete message on cell  2  for confirmation of the handover. After the handover, based on the received information at step  307 , the UE may continue using WLAN A for data transmission with new dedicated WLAN/3GPP interworking parameters at step  309  in this example, if the UE is still in the coverage area of WLAN A. 
         [0027]      FIG. 4  illustrates another example of signaling utilized by a UE and a network, NW, in accordance with an example embodiment of the application. In the example of  FIG. 4 , a UE  420 , such as for example, the UE  105  of  FIG. 1 , is camping on a cell  1  with a cell global identifier  1  under eNB 1   421 , such as for example, the eNB  101  of  FIG. 1 . The UE  420  reads system information at step  401  from eNB  1   421  where in this example three WLAN identifiers A, B and C are included for RAN assisted 3GPP/WLAN interworking. The system information may also include information indicating that the WLAN A, B and C can be used in cells with cell global identifiers  1  and  2 . In the example of  FIG. 4 , the UE is in coverage area of WLAN A, such as for example, the WLAN area  110  of  FIG. 1 . At step  402 , the NW transmits an RRCConnectionReconfiguration message on cell  1  to setup intra frequency measurement and to configure dedicated WLAN/3GPP interworking parameters. The UE transmits an RRCConnectionReconfigurationComplete message on cell  1  for confirmation at step  403 . Active data transmission starts between the UE and the network at step  404  after the RRC connection is reconfigured. If a criteria for starting the use of WLAN A is fulfilled, the UE can start to use WLAN A for data transmission at step  405 . 
         [0028]    When the UE  420  moves geographically and a neighbor cell  2  with a cell global identifier  2  under eNB 2   422  becomes better than the serving cell  421  (i.e. criteria for measurement reporting is fulfilled), the UE may transmit a MeasurementReport message on cell  1  to report event at step  406 . If the NW determines that the UE should handover to cell  2 , the NW transmits an RRCConnectionReconfiguration message at step  407  to order the UE to perform the handover to cell  2 . The new dedicated WLAN/3GPP interworking parameters may be included in the RRCConnectionReconfiguration message sent at step  407 . At step  408 , the UE transmits an RRCConnectionReconfigurationComplete message on cell  2  for confirmation of the handover. After the handover, based on the cell global identifier of cell  2 , the UE may continue using WLAN A for data transmission with new dedicated WLAN/3GPP interworking parameters at step  409  in this example if the UE is still in the coverage area of WLAN A. 
         [0029]    Reference is made to  FIG. 5  for illustrating a simplified block diagram of various example apparatuses that are suitable for use in practicing various example embodiments of this application. In  FIG. 5 , a network element, NE,  501 , such as for example, the eNB  101 , eNB  221 , eNB  321  or eNB  421 , is adapted for communication with a UE  511 , such as for example, the UE  105 , UE  220 , UE  320  or UE  420 . The UE  511  includes at least one processor  515 , at least one memory (MEM)  514  coupled to the at least one processor  515 , and a suitable transceiver (TRANS)  513  (having a transmitter (TX) and a receiver (RX)) coupled to the at least one processor  515 . The at least one MEM  514  stores a program (PROG)  512 . The TRANS  513  is for bidirectional wireless communications with the NE  501 . 
         [0030]    The NE  501  includes at least one processor  505 , at least one memory (MEM)  504  coupled to the at least one processor  505 , and a suitable transceiver (TRANS)  503  (having a transmitter (TX) and a receiver (RX)) coupled to the at least one processor  505 . The at least one MEM  504  stores a program (PROG)  502 . The TRANS  503  is for bidirectional wireless communications with the UE  511 . The NE  501  may be coupled to one or more cellular networks or systems, which is not shown in this figure. 
         [0031]    As shown in  FIG. 5 , the NE  501  may further include a WLAN/3GPP interworking control unit  506 . The unit  506 , together with the at least one processor  505  and the PROG  502 , may be utilized by the NE  501  in conjunction with various example embodiments of the application, as described herein. 
         [0032]    As shown in  FIG. 5 , the UE  511  may further include a WLAN/3GPP interworking unit  516 . The unit  516 , together with the at least one processor  515  and the PROG  512 , may be utilized by the UE  511  in conjunction with various example embodiments of the application, as described herein. 
         [0033]    At least one of the PROGs  502  and  512  is assumed to include program instructions that, when executed by the associated processor, enable the electronic apparatus to operate in accordance with the example embodiments of this disclosure, as discussed herein. 
         [0034]    In general, the various example embodiments of the apparatus  511  can include, but are not limited to, cellular phones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions. 
         [0035]    The example embodiments of this disclosure may be implemented by computer software or computer program code executable by one or more of the processors  505 ,  515  of the NE  501  and the UE  511 , or by hardware, or by a combination of software and hardware. 
         [0036]    The MEMs  504  and  514  may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. The processors  505  and  515  may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multi-core processor architecture, as non-limiting examples. 
         [0037]    Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein may be making UE behavior deterministic during network interworking in connection with cellular handover. This helps to improve the user experience. 
         [0038]    Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on an apparatus such as a user equipment, a NodeB or other mobile communication devices. If desired, part of the software, application logic and/or hardware may reside on a NE  501 , part of the software, application logic and/or hardware may reside on a UE  511 , and part of the software, application logic and/or hardware may reside on other chipset or integrated circuit. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a “computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable medium may comprise a computer-readable storage medium that may be any media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device. 
         [0039]    It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims. 
         [0040]    For example, it has been assumed that the interworking is between WLAN and 3GPP. It is straightforward to generalize the idea to cover the other type of networks. 
         [0041]    Further, the various names used for the described parameters are not intended to be limiting in any respect, as these parameters may be identified by any suitable names. For example, different message other than 3GPP RRC signaling can be used as the dedicated signaling exchanged between UE and network. 
         [0042]    If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and example embodiments of this invention, and not in limitation thereof.