PATENT DOCUMENT

Publication Number: US-10880797-B2
Application Number: US-201916520752-A
Country: US
Kind Code: B2

Title: Device and method for radio cell selection

Abstract:
This disclosure relates to a mobile device, comprising: a receiver configured to receive a radio signal comprising transmissions from a plurality of radio cells; and a processor configured to derive second information from the received radio signal, the second information indicating at least one neighboring radio cell, wherein the processor is configured to initiate a radio cell selection based on the second information if the second information indicates at least one neighboring radio cell configured for the first RAT.

Claims:
The invention claimed is: 
     
       1. A device, comprising:
 a receiver configured to receive a radio signal comprising transmissions from a plurality of radio cells; and 
 a processor configured to determine, from the received radio signal, second information indicating at least one neighboring radio cell, and to initiate a radio cell selection
 (i) based on the second information when the second information indicates at least one neighboring radio cell configured for a first radio access technology (RAT), or 
 (ii) based on first information in an absence of the second information indicating a neighboring radio cell that is configured for the first RAT. 
 
 
     
     
       2. The device of  claim 1 , wherein the first information is predetermined. 
     
     
       3. The device of  claim 1 , wherein the second information indicates at least one neighboring radio cell configured for a second RAT. 
     
     
       4. The device of  claim 3 , wherein the at least one neighboring radio cell configured for the first RAT is a radio cell according to a first mobile communication standard supporting the first RAT and the second RAT. 
     
     
       5. The device of  claim 3 , wherein the at least one neighboring radio cell configured for the second RAT is a radio cell according to a second mobile communication standard supporting the second RAT. 
     
     
       6. The device of  claim 3 , wherein:
 the at least one neighboring radio cell configured for the first RAT is assigned a first priority, 
 the at least one neighboring radio cell configured for the second RAT is assigned to a second priority, and 
 the first priority is higher than the second priority. 
 
     
     
       7. The device of  claim 1 , wherein the processor is configured to determine the second information from an inter-RAT neighbor cell list included as part of system information of a broadcast channel of a respective radio cell. 
     
     
       8. The device of  claim 1 , wherein the processor is configured to update the first information based on the second information determined from the received radio signal when the second information indicates at least one radio cell configured for the first RAT. 
     
     
       9. The device of  claim 1 , wherein the second information comprises frequency information, threshold information, and priority information of the at least one neighboring radio cell. 
     
     
       10. The device of  claim 1 , wherein the processor is configured to initiate the radio cell selection when the mobile device is camping on a radio cell that is configured for a RAT different from the first RAT. 
     
     
       11. The device of  claim 1 , wherein the first information is stored in a memory and is maintained across power cycles of the device. 
     
     
       12. The device of  claim 1 , wherein the processor is configured to stop initiating the radio cell selection when the radio cell selection based on the first information is not enabled and the second information indicates no neighboring radio cell configured for the first RAT. 
     
     
       13. The device of  claim 12 , wherein the processor is configured to reconfigure the first information with the second information determined from the received radio signal after a predetermined time period. 
     
     
       14. The device of  claim 1 , wherein the processor is controlled via a layer 3 protocol stack to initiate the radio cell selection. 
     
     
       15. A method for initiating a radio cell selection, comprising:
 receiving a radio signal comprising transmissions from a plurality of radio cells; 
 determining, from the received radio signal, second information indicating at least one neighboring radio cell; and 
 initiating a radio cell selection
 (i) based on the second information when the second information indicates at least one neighboring radio cell configured for a first radio access technology (RAT), or 
 (ii) based on first information in an absence of the second information indicating a neighboring radio cell that is configured for the first RAT. 
 
 
     
     
       16. The method of  claim 15 , wherein the second information indicates at least one neighboring radio cell configured for a second RAT. 
     
     
       17. The method of  claim 16 , wherein the at least one neighboring radio cell configured for the first RAT is a radio cell according to a first mobile communication standard supporting the first RAT and the second RAT. 
     
     
       18. The method of  claim 16 , wherein the at least one neighboring radio cell configured for the second RAT is a radio cell according to a second mobile communication standard supporting the second RAT. 
     
     
       19. The method of  claim 16 , wherein:
 the at least one neighboring radio cell configured for the first RAT is assigned a first priority, 
 the at least one neighboring radio cell configured for the second RAT is assigned a second priority, and 
 the first priority is higher than the second priority. 
 
     
     
       20. The method of  claim 15 , wherein the act of determining the second information includes determining the second information from an inter-RAT neighbor cell list included as part of system information of a broadcast channel of a respective radio cell. 
     
     
       21. The method of  claim 15 , further comprising: updating the first information based on the second information determined from the received radio signal when the second information indicates at least one radio cell configured for the first RAT. 
     
     
       22. A method for connecting a mobile device to a radio cell, the method comprising:
 receiving a radio signal comprising transmissions from a plurality of radio cells; 
 connecting the mobile device to a first radio cell based on first information indicating at least one neighboring radio cell that is configured for a first radio access technology (RAT); 
 determining, from the received radio signal, second information indicating at least one neighboring radio cell; and 
 connecting the mobile device to a second radio cell (i) based on the second information when the second information indicates at least one neighboring radio cell configured for a first radio access technology (RAT), or (ii) based on the first information in an absence of the second information indicating a neighboring radio cell that is configured for the first RAT. 
 
     
     
       23. The method of  claim 22 , further comprising:
 disconnecting the mobile device from the first radio cell before connecting the mobile device to the second radio cell. 
 
     
     
       24. The method of  claim 22 , wherein the first information is stored in a memory. 
     
     
       25. The method of  claim 22 , wherein the second information indicates at least one neighboring radio cell configured for a second RAT.

Description:
FIELD 
     The disclosure relates to a mobile device which performs initiating a radio cell selection in a communication network and a method for initiating a radio cell selection, in particular a self-configured high priority radio access technology (RAT) search. The disclosure further relates to fallback techniques between different radio access technologies. 
     BACKGROUND 
     In current mobile communications  100 , e.g. according to the 3GPP standard, when a mobile device  120  or User Equipment (UE) is in IDLE mode it performs neighboring inter-RAT cell measurement  121 ,  122 ,  123  and re-selects the best available cell found during the scanning as shown in  FIG. 1 . Depending on the network, UE  120  obtains an available inter-RAT (IRAT) neighbor cell list, e.g. including radio cells  111 ,  112 ,  113 , and only the cells from this neighbor cell list are regularly monitored by the UE  120  to find the best cell for re-selection. The network usually broadcasts this information on broadcast channels, for example, in a neighbor cell list indicating radio cells configured for specific Radio Access Technologies (RAT). It has shown from field trials that in most situations such an inter-RAT neighbor cell list is not correctly configured. As the UE  120  is completely dependent on the broadcasted neighbor cell list, even when it is aware of the cells of the preferred RAT (for example cell  111  configured for LTE, Long Term Evolution) in its vicinity where it camped previously, it may be stuck in that same low priority RAT (for example a 2G-GSM cell) due to a wrongly configured IRAT neighbor cell list. This in turn drastically reduces the data throughput performance of a multi-mode LTE capable UE even though the user is subscribed for LTE data services and a suitable LTE cell is available in its vicinity. 
     Hence, there is a need to improve the cell search in particular in communication networks with radio cells configured for different radio access technologies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. 
         FIG. 1  is a schematic diagram illustrating a communication system  100  with a mobile device  120  initiating radio cell selection between radio cells  111 ,  112 ,  113  configured for different RATS. 
         FIG. 2  is a flow chart of an exemplary method  200  for radio cell selection in which a preferred RAT order is LTE-UMTS-GSM and LTE neighboring cells are not configured in 2G-GSM. 
         FIG. 3  is a flow chart of an exemplary message protocol sequence  300  for a UE with LTE preference camped on GERAN cell. 
         FIG. 4  is a block diagram of a mobile device  400  according to the disclosure. 
         FIG. 5  is a schematic diagram of a method  500  for initiating a radio cell selection according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the invention may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     The following terms, abbreviations and notations will be used herein:
     RAT: radio access technology,   IRAT: Inter RAT,   SI2quarter: 2G system information 2 quarter message,   UMTS: Universal Mobile Telecommunication System   GSM: Global System for Mobile Communications   UTRA: UMTS Terrestrial Radio Access   EUTRA: evolved UMTS Terrestrial Radio Access   LTE: Long Term Evolution   UE: User Equipment, mobile device, cellular handset   IMS: IP multimedia subsystem   SRVCC: Single Radio Voice Call Continuity   CS: circuit switched   CSFB: circuit switched fallback   2G/3G/4G: 2 nd /3 rd /4 th  Generation   PLMN: Public Land Mobile Network   

     It is understood that comments made in connection with a described method may also hold true for a corresponding device configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such a unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise. 
     The techniques described herein may be implemented in wireless communication networks, in particular communication networks based on mobile communication standards such as LTE, in particular LTE-A and/or OFDM and successor standards such as 5G. The methods are also applicable for high speed communication standards from the 802.11 family according to the WiFi alliance, e.g. 802.11ad and successor standards. The methods and devices described below may be implemented in electronic devices such as cellular handsets, mobile or wireless devices (or mobile stations or User Equipment (UE)). The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives. 
     In the following, embodiments are described with reference to the drawings, wherein like reference numerals are generally utilized to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects of embodiments. However, it may be evident to a person skilled in the art that one or more aspects of the embodiments may be practiced with a lesser degree of these specific details. The following description is therefore not to be taken in a limiting sense. 
     The various aspects summarized may be embodied in various forms. The following description shows by way of illustration various combinations and configurations in which the aspects may be practiced. It is understood that the described aspects and/or embodiments are merely examples, and that other aspects and/or embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present disclosure. 
     The basic principle of systems described hereinafter is as follows: Whenever the UE is successfully camped on a suitable cell, it will store the latest predefined number of cell information along with their reselection thresholds, priority and PLMN (public land mobile network) values after acquiring these for both serving cell and its neighbor cells from their respective system information messages. And upon detecting any of the scenario where the neighbor cell list is not configured for high priority RAT, UE will perform self-configured measurements on previously stored cells and may follow the default defined reselection algorithms, e.g. as defined in 3GPP, in particular TS 45.008 (V9.4.0, 2010-10), chapter 6.6.6. Advantages are improved time in the preferred RAT, i.e. a RAT with good throughput, and thus a better user experience. 
       FIG. 2  is a flow chart of an exemplary method  200  for radio cell selection in which a preferred RAT order is LTE-UMTS-GSM and LTE neighboring cells are not configured in 2G-GSM. 
     When the method  200  is invoked  201 , the UE is camped and registered on an LTE cell. EUTRA-AS stores its own reselection thresholds, priorities and PLMN information related to serving frequency and neighbor frequencies for high priority search according to block  202 . When an IMS call is started (block  203 ), UE moved to 3G-UMTS cell with SRVCC (Single Radio Voice Call Continuity) handover (block  204 ). At next block  205 , UE moved to 2G-GSM cell with CS (circuit-switched) handover. When the call is disconnected, UE moved to IDLE state (block  206 ). In this IDLE state UE can perform cell search measurements for which a neighbor cell list is required. Hence, UE checks in block  207  if an LTE neighbor cell list, i.e. a neighbor cell list including cells which are capable of LTE RAT, is broadcast in system information. If such an LTE neighbor cell list is available, UE can configure measurement on neighbor cell from system information, i.e. by using this LTE neighbor cell list (see block  209 ). However, if such an LTE neighbor cell list is not available, UE checks if self-configured high priority RAT search is enabled, i.e. if UE stores its own list from previously camped cells according to the concept of the disclosure (see block  208 ). 
     If self-configured high priority RAT search is enabled, UE can configure measurement on neighbor cell from previously camped cell, i.e. from its own LTE neighbor cell list (see block  210 ). However, if self-configured high priority RAT search is not enabled, UE will remain in 2G-GSM (block  212 ) if high-priority RAT neighbor cell information not provided in System Information Broadcast of service cell. For both cases that a neighbor cell list is available, either broadcast from system information according to block  207  or obtained from self-configuration according to block  208 , UE performs IDLE mode cell re-selection procedure (block  211 ) before the method  200  ends  213 . 
     The exemplary implementation of  FIG. 2  provides a mechanism to return to high priority/preferred RAT from a low priority/non-preferred RAT cell when such cells are available but the network didn&#39;t configure IRAT neighbor cells in system information. Currently any such mechanism is not provided in the 3GPP standards. The scenario in the flowchart of  FIG. 2  shows difference between the UE behavior with and without the disclosed solution. The flowchart of  FIG. 2  explains the exemplary scenario where the preferred RAT order is LTE-UMTS-GSM and in 2G-GSM, LTE neighboring cells are not configured. The disclosed solution is not limited to the RAT combination shown in  FIG. 2 . Any other high priority, i.e. preferred RAT and low priority, i.e. non-preferred RAT may be applied. 
       FIG. 3  is a flow chart of an exemplary message protocol sequence  300  for a UE with LTE preference camped on GERAN cell. 
     Different user equipment entities are shown: A non access stratum (NAS)  301 , an EUTRA access stratum  302 , a UMTS access stratum  303 , a GSM access stratum  304  and the network (NW)  305 . 
     The non access stratum (NAS)  301  is a 3GPP defined protocol layer that helps UE to register with Network and access services via multiple available access stratum. A non access stratum  301  has interfaces to multiple access stratum, i.e. to EUTRA access stratum  302 , UMTS access stratum  303 , GSM access stratum  304 . 
     In the exemplary implementation of  FIG. 3 , the UE NAS has access to the network  305  via EUTRA-AS  302  or GSM-AS  304  or via UMTS-AS. 
     At an initial stage, the UE has access to EUTRA cell via EUTRA-AS  302 , where LTE-ERRC radio resource control stores an exemplary number of “n” EUTRA frequency entries with information about thresholds and priorities of previously registered cells or neighbor cells (block  306 ). Depending on different use cases as described below, the UE may be made to camp on a GERAN cell connecting to the GSM-AS  304 . In this GERAN network no EUTRA neighbor cell information is configured in system information, i.e. in SI2quarter information (block  307 ). 
     GERAN radio resource (RR) will retrieve the stored EUTRAN frequency list specific to the camped PLMN, i.e. from the neighbor cell list stored in block  306  (block  308 ). Using this stored EUTRAN frequency list, UE will configure IRAT measurements on these high priority EUTRA frequencies (block  311 ). If then an LTE cell is found and the specific reselection criteria are met by this LTE cell (block  312 ), UE can reselect the found LTE cell (sequence  313 ) and connect to the EUTRA-AS  302 . Otherwise (block  312 ), UE may stop measuring the stored LTE frequencies and may re-configure them after a pre-determined periodicity in order to save battery power (block  314 ). 
     As can be seen from the message protocol sequence  300  of  FIG. 3 , that represents a live network log, a UE with LTE preference (RAT preference order 4G-3G-2G) is reselected from LTE and camped on GERAN cell. But as that cell has no LTE neighbor cells in broadcast information, the UE is not able to move back to LTE even when it knows that suitable LTE cells are available. There are multiple ways how an UE can camp on a GERAN cell which is not configured with LTE neighbor cells. The following are a few of possible cases.
     1. UE can be chosen to camp on GERAN cell via cell selection.   2. UE can be re-selected to GERAN cell via IRAT reselection from other RATS.   3. During SRVCC, network may move to a GERAN cell (which does not have EUTRAN neighbor cells in its SI2Quarter information) by means of an IRAT handover.   4. During a CSFB call, network may redirect to a UTRAN cell and during the CS Call, the UE may move to a GERAN Cell (which does not have EUTRAN neighbor cells in its SI2Quarter information) by means of an IRAT handover.   5. Extended Service Request is sent by UE for a CSFB call and if network does not provide redirection info in the Connection Release or T3417ext counter expires then UE may move to such a GERAN cell in order to perform the CS Call.   

     When implementing the solution according to this disclosure, after camping in such a GERAN cell, UE can retrieve the stored EUTRAN frequencies specific to the camped PLMN and then configure them for performing EUTRAN IRAT measurements and apply higher priority based reselection algorithm to reselect to a suitable EUTRAN cell if available. 
     As UE stores all necessary information including the thresholds and priority data, UE can only reselect to LTE when the corresponding reselection criteria (e.g. according to 3GPP) is actually met. Hence, such a UE can avoid a Ping-Pong reselection to/from LTE and thereby achieving stability. 
     Due to mobility when even the stored LTE frequencies do not yield good measurements for reselection, UE can stop configuring these frequencies for measurements and may re-configure with a pre-defined periodicity in order to save battery. The stored list data base can be maintained across power cycles, hence even after the next boot up, when UE camped in 2G, the list can be used to reselect to LTE. 
       FIG. 4  is a block diagram of a mobile device  400  according to the disclosure. 
     The mobile device  400  includes a receiver  401 , an optional memory  402  and a processor  403 , e.g. a baseband (BB) processor. The receiver  401  is configured to receive a radio signal  408  comprising transmissions from a plurality of radio cells, e.g. transmissions  121 ,  122 ,  123  from radio cells  111 ,  112 ,  113  as shown in  FIG. 1 . The optional memory  402  is configured to store first information  404  indicating at least one neighboring radio cell which is configured for a first radio access technology (RAT). Note that the first information does not need to be stored in a memory. The first information can be predetermined, i.e. known by the processor  403 . The processor  403  is configured to derive second information  405  from the received radio signal  408 . The second information  405  indicates at least one neighboring radio cell. The processor  403  is configured to initiate a radio cell selection  407  based on the second information  405  if  406  the second information  405  indicates at least one neighboring radio cell configured for the first RAT. Alternatively, the processor  403  can initiate the radio cell selection based on the predetermined first information if the second information does not provide information about a neighboring radio cell which is configured for the first RAT. 
     The processor  403  may implement one of the methods  200 ,  300  described above with respect to  FIGS. 2 and 3 . The first information  404  may include the stored neighbor cell list according to blocks  208 ,  210  in  FIG. 2  or according to block  306  in  FIG. 3 . The second information  405  may include the neighbor cell list received from the system information comprised in the received radio signal  408 , e.g. according to block  209  in  FIG. 2  or according to SI2quarter information in blocks  307 ,  308  in  FIG. 3 . 
     The second information  405  may indicate one or more neighboring radio cells which are configured for a second RAT. 
     The one or more neighboring radio cells which are configured for the first RAT may be radio cells according to a first mobile communication standard supporting both, the first RAT and the second RAT, e.g. GSM and LTE as described above with respect to  FIG. 3 . 
     The one or more neighboring radio cells which are configured for the second RAT may be radio cells according to a second mobile communication standard which only support the second RAT and not the first RAT, e.g. only GSM and not LTE according to the description with respect to  FIG. 3 . 
     The one or more neighboring radio cells which are configured for the first RAT may be assigned to a first priority. The one or more neighboring radio cells which are configured for the second RAT may be assigned to a second priority. In one example, the first priority is higher than the second priority. 
     The processor  403  may be configured to derive the second information  405  from an inter-RAT neighbor cell list comprised in system information of a broadcast channel of a respective radio cell. 
     The processor  403  may be configured to update the first information  404  stored in the memory  402  based on the second information  405  derived from the received radio signal  408  if the second information  405  indicates at least one radio cell which is configured for the first RAT. 
     The second information  405  may include frequency information, threshold information and priority information of the one or more neighboring radio cells. 
     The processor  403  may be configured to initiate the radio cell selection when the mobile device is camping on a radio cell which is configured for a RAT that is different from the first RAT. 
     The processor  403  may be configured to initiate the radio cell selection when the mobile device is in an idle mode. 
     The first information  404  may be stored in a section of the memory which is maintained across power cycles, i.e. a power-off resistant section of the memory. 
     The processor  403  may be configured to stop initiating the radio cell selection if the radio cell selection based on the first information  404  is not enabled and the second information  405  indicates no neighboring radio cell configured for the first RAT, e.g. as described in block  314  of  FIG. 3 . 
     The processor  403  may be configured to reconfigure the first information  404  stored in the memory  402  with the second information  405  which is derived from the received radio signal  408  after a predetermined time period. This may ensure that the first information  404  stored in the memory  402  indicates the latest radio cell environment. 
     The memory  402  may store a layer 3 protocol stack controlling the processor  403  to initiate the radio cell selection. 
       FIG. 5  is a schematic diagram of a method  500  for initiating a radio cell selection according to the disclosure. The method  500  may for example be implemented on a processor  403  as described above with respect to  FIG. 4  or on any other computer. 
     The method  500  includes: receiving  501  a radio signal, e.g. a radio signal  408  as shown in  FIG. 4 , comprising transmissions from a plurality of radio cells, e.g. radio cells  111 ,  112 ,  113  as shown in  FIG. 1 . 
     The method  500  includes: deriving  502  second information from the received radio signal, e.g. second information  405  as described above with respect to  FIG. 4 , the second information indicating at least one neighboring radio cell. 
     The method  500  further includes: initiating  503  a radio cell selection based on the second information  405  if the second information indicates at least one radio cell configured for a first radio access technology (RAT), otherwise based on predetermined first information, e.g. first information  404  as described above with respect to  FIG. 4 , indicating at least one neighboring radio cell which is configured for the first RAT. 
     The second information may indicate at least one neighboring radio cell configured for a second RAT. The at least one neighboring radio cell which is configured for the first RAT may be a radio cell according to a first mobile communication standard supporting both, the first RAT and the second RAT. 
     The at least one neighboring radio cell configured for the second RAT may be a radio cell according to a second mobile communication standard only supporting the second RAT, i.e. not supporting the first RAT. 
     The at least one neighboring radio cell which is configured for the first RAT may be assigned to a first priority; the at least one neighboring radio cell configured for the second RAT may be assigned to a second priority, wherein the first priority is higher than the second priority. 
     The method  500  may further comprise: deriving the second information from an inter-RAT neighbor cell list comprised in system information of a broadcast channel of a respective radio cell. The method  500  may further comprise: updating the first information stored in the memory based on the second information derived from the received radio signal if the second information indicates at least one radio cell configured for the first RAT. 
     The second information may include frequency information, threshold information and priority information of the at least one neighboring radio cell. 
     The method  500  may further comprise: initiating the radio cell selection when the mobile device is camping on a radio cell which is configured for a RAT different from the first RAT. The method  500  may further comprise: initiating the radio cell selection when the mobile device is in an idle mode. The first information may be stored in a section of the memory which is maintained across power cycles. 
     The method  500  may further comprise: stopping initiating the radio cell selection if the radio cell selection based on the first information is not enabled and the second information indicates no neighboring radio cell configured for the first RAT, e.g. according to block  314  described above with respect to  FIG. 3 . 
     The method  500  may further comprise: reconfiguring the first information stored in the memory with the second information derived from the received radio signal after a predetermined time period. The method  500  may further comprise: storing a layer 3 protocol stack which is configured to control the processor to initiate the radio cell selection. 
     A method for connecting a mobile device to a radio cell (not depicted) includes: receiving a radio signal comprising transmissions from a plurality of radio cells, e.g. radio cells  111 ,  112 ,  113  as described above with respect to  FIG. 1 ; connecting the mobile device to a first radio cell based on predetermined first information indicating at least one neighboring radio cell which is configured for a first radio access technology (RAT); deriving second information from the received radio signal, the second information indicating at least one neighboring radio cell; and connecting the mobile device to a second radio cell based on the second information if the second information indicates at least one radio cell configured for the first RAT, otherwise based on the first information. The first information may correspond to the first information  404  as described above with respect to  FIG. 4 . The second information may correspond to the second information  405  as described above with respect to  FIG. 4 . 
     The method may further include: disconnecting the mobile device from the first radio cell before connecting the mobile device to the second radio cell. The first information may be stored in a memory. The second information may indicates at least one neighboring radio cell configured for a second RAT. The at least one neighboring radio cell configured for the first RAT may be a radio cell according to a first mobile communication standard supporting both, the first RAT and the second RAT. The at least one neighboring radio cell configured for the second RAT may be a radio cell according to a second mobile communication standard only supporting the second RAT, e.g. as described above with respect to  FIGS. 3 and 4 . 
     The at least one neighboring radio cell configured for the first RAT may be assigned to a first priority, and the at least one neighboring radio cell configured for the second RAT may be assigned to a second priority, wherein the first priority is higher than the second priority. 
     The method may further include: deriving the second information from an inter-RAT neighbor cell list comprised in system information of a broadcast channel of a respective radio cell. The method may further include: updating the first information stored in the memory based on the second information derived from the received radio signal if the second information indicates at least one radio cell configured for the first RAT. The second information may include frequency information, threshold information and priority information of the at least one neighboring radio cell. 
     The devices and systems described in this disclosure may be implemented as Digital Signal Processors (DSP), micro-controllers or any other side-processor or hardware circuit on a chip or an application specific integrated circuit (ASIC). 
     Embodiments described in this disclosure can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations thereof, e.g. in available hardware of mobile devices or in new hardware dedicated for processing the methods described herein. 
     The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing blocks described herein, in particular the methods  200 ,  300 ,  500  described above with respect to  FIGS. 2, 3 and 5  and the computing blocks described above with respect to  FIG. 4 . Such a computer program product may include a non-transient readable storage medium storing program code thereon for use by a processor, the program code comprising instructions for performing the methods or the computing blocks as described above. 
     EXAMPLES 
     The following examples pertain to further embodiments. Example 1 is a mobile device, comprising: a receiver configured to receive a radio signal comprising transmissions from a plurality of radio cells; and a processor configured to derive second information from the received radio signal, the second information indicating at least one neighboring radio cell, wherein the processor is configured to initiate a radio cell selection based on the second information if the second information indicates at least one neighboring radio cell configured for a first radio access technology (RAT). 
     In Example 2, the subject matter of Example 1 can optionally include that the processor is configured to initiate the radio cell selection based on predetermined first information if the second information does not provide information about a neighboring radio cell which is configured for the first RAT. 
     In Example 3, the subject matter of Example 2 can optionally include that the second information indicates at least one neighboring radio cell configured for a second RAT. 
     In Example 4, the subject matter of Example 3 can optionally include that the at least one neighboring radio cell configured for the first RAT is a radio cell according to a first mobile communication standard supporting both, the first RAT and the second RAT. 
     In Example 5, the subject matter of any one of Examples 3-4 can optionally include that the at least one neighboring radio cell configured for the second RAT is a radio cell according to a second mobile communication standard only supporting the second RAT. 
     In Example 6, the subject matter of any one of Examples 3-5 can optionally include that the at least one neighboring radio cell configured for the first RAT is assigned to a first priority, wherein the at least one neighboring radio cell configured for the second RAT is assigned to a second priority, wherein the first priority is higher than the second priority. 
     In Example 7, the subject matter of any one of Examples 1-5 can optionally include that the processor is configured to derive the second information from an inter-RAT neighbor cell list comprised in system information of a broadcast channel of a respective radio cell. 
     In Example 8, the subject matter of any one of Examples 2-7 can optionally include that the processor is configured to update the first information based on the second information derived from the received radio signal if the second information indicates at least one radio cell configured for the first RAT. 
     In Example 9, the subject matter of any one of Examples 1-8 can optionally include that the second information comprises frequency information, threshold information and priority information of the at least one neighboring radio cell. 
     In Example 10, the subject matter of any one of Examples 1-9 can optionally include that the processor is configured to initiate the radio cell selection when the mobile device is camping on a radio cell which is configured for a RAT different from the first RAT. 
     In Example 11, the subject matter of any one of Examples 1-10 can optionally include that the first information is stored in a memory section which is maintained across power cycles. 
     In Example 12, the subject matter of any one of Examples 1-11 can optionally include that the processor is configured to stop initiating the radio cell selection if the radio cell selection based on the first information is not enabled and the second information indicates no neighboring radio cell configured for the first RAT. 
     In Example 13, the subject matter of Example 12 can optionally include that the processor is configured to reconfigure the first information with the second information derived from the received radio signal after a predetermined time period. 
     In Example 14, the subject matter of any one of Examples 1-13 can optionally include a layer 3 protocol stack controlling the processor to initiate the radio cell selection. 
     Example 15 is a method for initiating a radio cell selection, the method comprising: receiving a radio signal comprising transmissions from a plurality of radio cells; deriving second information from the received radio signal, the second information indicating at least one neighboring radio cell; and initiating a radio cell selection based on the second information if the second information indicates at least one radio cell configured for a first radio access technology (RAT), otherwise based on predetermined first information indicating at least one neighboring radio cell which is configured for the first RAT. 
     In Example 16, the subject matter of Example 15 can optionally include that the second information indicates at least one neighboring radio cell configured for a second RAT. 
     In Example 17, the subject matter of Example 16 can optionally include that the at least one neighboring radio cell configured for the first RAT is a radio cell according to a first mobile communication standard supporting both, the first RAT and the second RAT. 
     In Example 18, the subject matter of any one of Examples 16-17 can optionally include that the at least one neighboring radio cell configured for the second RAT is a radio cell according to a second mobile communication standard only supporting the second RAT. 
     In Example 19, the subject matter of any one of Examples 16-18 can optionally include that the at least one neighboring radio cell configured for the first RAT is assigned to a first priority, wherein the at least one neighboring radio cell configured for the second RAT is assigned to a second priority, wherein the first priority is higher than the second priority. 
     In Example 20, the subject matter of any one of Examples 15-19 can optionally include: deriving the second information from an inter-RAT neighbor cell list comprised in system information of a broadcast channel of a respective radio cell. 
     In Example 21, the subject matter of any one of Examples 15-20 can optionally include: updating the first information based on the second information derived from the received radio signal if the second information indicates at least one radio cell configured for the first RAT. 
     In Example 22, the subject matter of any one of Examples 15-21 can optionally include that the second information comprises frequency information, threshold information and priority information of the at least one neighboring radio cell. 
     In Example 23, the subject matter of any one of Examples 15-22 can optionally include: initiating the radio cell selection when the mobile device is camping on a radio cell which is configured for a RAT different from the first RAT. 
     In Example 24, the subject matter of any one of Examples 15-23 can optionally include: initiating the radio cell selection when the mobile device is in an idle mode. 
     In Example 25, the subject matter of any one of Examples 15-24 can optionally include that the first information is stored in a memory section which is maintained across power cycles. 
     In Example 26, the subject matter of any one of Examples 15-25 can optionally include: stopping initiating the radio cell selection if the radio cell selection based on the first information is not enabled and the second information indicates no neighboring radio cell configured for the first RAT. 
     In Example 27, the subject matter of Example 26 can optionally include: reconfiguring the first information with the second information derived from the received radio signal after a predetermined time period. 
     In Example 28, the subject matter of any one of Examples 15-27 can optionally include: storing a layer 3 protocol stack which is configured to control the processor to initiate the radio cell selection. 
     Example 29 is a method for connecting a mobile device to a radio cell, the method comprising: receiving a radio signal comprising transmissions from a plurality of radio cells; connecting the mobile device to a first radio cell based on predetermined first information indicating at least one neighboring radio cell which is configured for a first radio access technology (RAT); deriving second information from the received radio signal, the second information indicating at least one neighboring radio cell; and connecting the mobile device to a second radio cell based on the second information if the second information indicates at least one radio cell configured for the first RAT, otherwise based on the first information. 
     In Example 30, the subject matter of Example 29 can optionally include: disconnecting the mobile device from the first radio cell before connecting the mobile device to the second radio cell. 
     In Example 31, the subject matter of any one of Examples 29-30 can optionally include that the first information is stored in a memory. 
     In Example 32, the subject matter of any one of Examples 29-31 can optionally include that the second information indicates at least one neighboring radio cell configured for a second RAT. 
     In Example 33, the subject matter of Example 32 can optionally include that the at least one neighboring radio cell configured for the first RAT is a radio cell according to a first mobile communication standard supporting both, the first RAT and the second RAT. 
     In Example 34, the subject matter of any one of Examples 32-33 can optionally include that the at least one neighboring radio cell configured for the second RAT is a radio cell according to a second mobile communication standard only supporting the second RAT. 
     In Example 35, the subject matter of any one of Examples 32-34 can optionally include that the at least one neighboring radio cell configured for the first RAT is assigned to a first priority, wherein the at least one neighboring radio cell configured for the second RAT is assigned to a second priority, wherein the first priority is higher than the second priority. 
     In Example 36, the subject matter of any one of Examples 29-35 can optionally include: deriving the second information from an inter-RAT neighbor cell list comprised in system information of a broadcast channel of a respective radio cell. 
     In Example 37, the subject matter of any one of Examples 29-36 can optionally include: updating the first information based on the second information derived from the received radio signal if the second information indicates at least one radio cell configured for the first RAT. 
     In Example 38, the subject matter of any one of Examples 29-37 can optionally include that the second information comprises frequency information, threshold information and priority information of the at least one neighboring radio cell. 
     Example 39 is a device for initiating a radio cell selection, the device comprising: means for receiving a radio signal comprising transmissions from a plurality of radio cells; means for deriving second information from the received radio signal, the second information indicating at least one neighboring radio cell; and means for initiating a radio cell selection based on the second information if the second information indicates at least one radio cell configured for a first radio access technology (RAT), otherwise based on predetermined first information indicating at least one neighboring radio cell which is configured for the first RAT. 
     In Example 40, the subject matter of Example 39 can optionally include that the second information indicates at least one neighboring radio cell configured for a second RAT. 
     Example 41 is a communication system, comprising: a receiver component configured to: receive a radio signal comprising transmissions from a plurality of radio cells; a connection component configured to connect to a first radio cell based on predetermined first information indicating at least one neighboring radio cell which is configured for a first radio access technology (RAT); and a processing component configured to derive second information from the received radio signal, the second information indicating at least one neighboring radio cell, wherein the connection component is configured to connect to a second radio cell based on the second information if the second information indicates at least one radio cell configured for the first RAT, otherwise based on the first information. 
     In Example 42, the subject matter of Example 41 can optionally include that the first information is stored in a memory section which is maintained across power cycles. 
     In Example 43, the subject matter of any one of Examples 41-42 can optionally include that the second information indicates at least one neighboring radio cell configured for a second RAT. 
     Example 44 is a computer readable non-transitory medium on which computer instructions are stored which when executed by a computer cause the computer to perform the method of any one of Examples 15 to 38. 
     In addition, while a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “include”, “have”, “with”, or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprise”. Furthermore, it is understood that aspects of the disclosure may be implemented in discrete circuits, partially integrated circuits or fully integrated circuits or programming means. Also, the terms “exemplary”, “for example” and “e.g.” are merely meant as an example, rather than the best or optimal. 
     Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein. 
     Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Metadata:
Filing Date: 20190724
Publication Date: 20201229
Grant Date: 20201229
Priority Date: 20170929
Inventors: DASH, Deepak
BASAVARAJAPPA, Nitin Gowda
KOTA, GURUNADHA RAO
KUPPELUR, NITIN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04W36/00224", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/00226", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/00835", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W48/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W88/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W88/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00835", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W48/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W88/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0022", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/0083", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W36/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W48/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00835", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W36/00226", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W36/00224", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 65898077