FIELD

The subject matter disclosed herein relates generally to wireless communications and more particularly relates to efficient mobility handling during V2X communication.

BACKGROUND

The following abbreviations are herewith defined, at least some of which are referred to within the following description: Third Generation Partnership Project (“3GPP”), Fifth Generation Core Network (“5CG”), Fifth Generation System (“5GS”), Authentication, Authorization and Accounting (“AAA”), Access and Mobility Management Function (“AMF”), Positive-Acknowledgment (“ACK”), Application Programming Interface (“API”), Access Stratum (“AS”), Base Station (“BS”), Control Element (“CE”), Connection Mode (“CM”, this is a NAS state in 5GS), Core Network (“CN”), Control Plane (“CP”), Downlink Control Information (“DCI”), Downlink (“DL”), Discontinuous Transmission (“DTX”), Evolved Node-B (“eNB”), Evolved Packet Core (“EPC”), Evolved Packet System (“EPS”), EPS Mobility Management (“EMM”, this is a NAS state in EPS), Frequency Division Duplex (“FDD”), Frequency Division Multiple Access (“FDMA”), General Packet Radio Service (“GPRS”), Global System for Mobile Communications (“GSM”), Hybrid Automatic Repeat Request (“HARQ”), Home Subscriber Server (“HSS”), Home Public Land Mobile Network (“HPLMN”), Information Element (“IE”), Long Term Evolution (“LTE”), Multiple Access (“MA”), Mobility Management (“MM”), Mobility Management Entity (“MME”), Negative-Acknowledgment (“NACK”) or (“NAK”), New Generation (5G) Node-B (“gNB”), New Generation Radio Access Network (“NG-RAN”, a RAN used for 5GS networks), New Radio (“NR”, a 5G radio access technology; also referred to as “5G NR”), Non-Access Stratum (“NAS”), Network Exposure Function (“NEF”), Network Slice Selection Assistance Information (“NSSAI”), Packet Data Unit (“PDU”, used in connection with ‘PDU Session’), Physical Broadcast Channel (“PBCH”), Physical Cell Identity (“PCI”), Physical Downlink Control Channel (“PDCCH”), Physical Downlink Shared Channel (“PDSCH”), Pattern Division Multiple Access (“PDMA”), Physical Hybrid ARQ Indicator Channel (“PHICH”), Physical Random Access Channel (“PRACH”), Physical Resource Block (“PRB”), Physical Uplink Control Channel (“PUCCH”), Physical Uplink Shared Channel (“PUSCH”), Public Land Mobile Network (“PLMN”), Radio Access Network (“RAN”), Radio Access Technology (“RAT”), Radio Resource Control (“RRC”), Random-Access Channel (“RACH”), Registration Area (“RA”, similar to tacking area list used in LTE/EPC), Registration Management (“RM”, refers to NAS layer procedures and states), Receive (“RX”), Radio Link Control (“RLC”), Shared Channel (“SCH”), Session Management (“SM”), Session Management Function (“SMF”), Sidelink (“SL”), Single Network Slice Selection Assistance Information (“S-NSSAI”), System Information Block (“SIB”), Synchronization Signal (“SS”), Tracking Area (“TA”), Transport Block (“TB”), Transport Block Size (“TBS”), Time-Division Duplex (“TDD”), Time Division Multiplex (“TDM”), Transmit (“TX”), Unified Data Management (“UDM”), User Data Repository (“UDR”), Uplink Control Information (“UCI”), User Entity/Equipment (Mobile Terminal) (“UE”), Uplink (“UL”), User Plane (“UP”), Universal Mobile Telecommunications System (“UMTS”), Visited Public Land Mobile Network (“VPLMN”), and Worldwide Interoperability for Microwave Access (“WiMAX”). As used herein, “HARQ-ACK” may represent collectively the Positive Acknowledge (“ACK”) and the Negative Acknowledge (“NACK”) and Discontinuous Transmission (“DTX”). ACK means that a TB is correctly received while NACK (or NAK) means a TB is erroneously received. DTX means that no TB was detected.

In certain wireless communication systems, V2X communication allows vehicles to communicate with moving parts of the traffic system around them. A UE capable of NR and LTE communication may be provided V2X communication resources for network scheduled V2X communication for both NR and LTE RATs (i.e. Mode-1 resources in NR SL and Mode-3 resources in LTE SL) as well as V2X communication resources for UE scheduled V2X communication for both the RATs (i.e. Mode-2 resources in NR SL and Mode-4 resources in LTE SL).

In LTE V2X communication, the resources provided for Mode-3 and Mode-4 V2X communication by the serving cell are not used anymore when a mobility event occurs, such as reception of handover command/T304 start, or RLF triggering/T310 start. Here, an “exceptional” resource pool is used for Mode-4 based communication. However, it is unclear what happens to V2X communication resources for the one RAT (e.g., RAT-2) when a mobility event in the other, serving RAT (e.g., RAT-1).

BRIEF SUMMARY

Disclosed are procedures for efficient mobility handling during V2X communication. One method of a UE, e.g., for mobility handling during V2X communication, includes communicating using a first V2X resource while in a first serving cell having a first RAT, detecting a mobility event of the first cell and switching to a second cell in response to the mobility event, the second cell different than the first cell. The method includes communicating using the first V2X resource on the second cell until a trigger condition occurs and switching to a second V2X resource in response to occurrence of the trigger condition.

