Abstract: A User Equipment (UE) communicates with one or both of a first 3GPP core network and a second 3GPP core network over one or both of a 3GPP access and a non-3GPP access. The communication includes: receiving, from the first 3GPP core network, a reject message; and searching for another suitable cell or another suitable Access Point (AP), when the reject message is received over the 3GPP access or the non-3GPP access and the UE is registered with the first 3GPP core network or the second 3GPP core network over the 3GPP access or the non-3GPP access.

Abstract: Examples pertaining to optimized allocation of new equipment identifier in mobile communications are described. An apparatus receives, from a network, an assignment of a plurality of temporary identities. The apparatus identifies itself with one of the plurality of temporary identities in performing a procedure with the network.

Abstract: A method of supporting reception of standalone SERVICE ACCEPT message is proposed. In one embodiment, a new timer is started when the UE determines successful completion of the service request procedure and has not received SERVICE ACCEPT during the procedure. In an alternative embodiment, an existing timer T3417 or T3417ext can be used to define the allowed time window for the reception of SERVICE ACCEPT. While the timer is running, the UE can treat the SERVICE ACCEPT message as successfully received and the message does not cause protocol error.

Abstract: A User Equipment (UE) including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception. The controller selects a PLMN via the wireless transceiver, and determines whether a predetermined ciphering algorithm is adopted for a Non-Access Stratum (NAS) security context. In response to selecting the PLMN and the predetermined ciphering algorithm being adopted for the NAS security context, the controller sends an initial NAS message in which Information Elements (IEs) are in cleartext only to the selected PLMN via the wireless transceiver.

Abstract: Examples pertaining to improved Globally Unique Temporary Identity (GUTI) allocation after establishment of mobile-terminated connection in mobile communications are described. An apparatus implemented in a UE receives a paging message from a network node of a wireless network. The apparatus then transmits a request to the network node responsive to receiving the paging message. In response to transmitting the request, the apparatus receives a signaling from the network node, with the signaling indicating a new temporary identity of the UE.

Abstract: Methods and apparatus are provided for handling of non-integrity reject message in the 5G system. In one novel aspect, the UE upon receiving the reject message via one access without integrity protection, retries one or more other accesses for one or more times before treating the rejection genuine. In one embodiment, the UE attempts the same 5GMM procedure over another access in the same cell/tracking area (TA). The alternative access including other types of 3GPP access and non-3GPP access. Subsequently, the UE can search the service from another cell/TA or another PLMN. In one embodiment, if the UE receives reject cause invalidating the UE with one access without integrity protection, the UE tries the system a few times before treating the reject genuine by tracking an invalidating counter, which is increased by one each time the rejection is received with a cause value invalidating the UE.

Abstract: Methods and apparatus are provided for handling of non-integrity reject message in the 5G system. In one novel aspect, the UE upon receiving the reject message via one access without integrity protection, retries one or more other accesses for one or more times before treating the rejection genuine. In one embodiment, the UE attempts the same 5GMM procedure over another access in the same cell/tracking area (TA). The alternative access including other types of 3GPP access and non-3GPP access. Subsequently, the UE can search the service from another cell/TA or another PLMN. In one embodiment, if the UE receives reject cause invalidating the UE with one access without integrity protection, the UE tries the system a few times before treating the reject genuine by tracking an invalidating counter, which is increased by one each time the rejection is received with a cause value invalidating the UE.

Abstract: Examples pertaining to detection of rogue cells in 5G mobile communications are described. A processor of an apparatus generates at least a part of a request, using a concealment function, and transmits the request to a communication entity. The processor then receives a response message from the communication entity. The processor determines, based on a parameter in the response message, whether the communication entity is a network node of a genuine Public Land Mobile Network (PLMN) or a rogue cell faking to be genuine.

Abstract: Examples pertaining to no subscription permanent identifier (SUPI) or no non-3GPP coverage in 5G mobile communications are described. A processor controls a communication device of a UE to connect to one or more wireless networks and receive one or more 5GS services via a 3GPP access and a non-3GPP access. The processor performs either a first procedure or a second procedure. The first procedure involves: (i) detecting either no Subscriber Identity Module (SIM) being inserted in the UE or a SIM inserted in the UE being invalid; and (ii) entering the UE into a 5G no-SUPI substate responsive to the detecting. The second procedure involves: (i) performing registration or determining that the UE is registered to one or more 5GS services over the non-3GPP access; (ii) detecting an absence of non-3GPP coverage; and (iii) entering the UE into a no access point available substate responsive to the detecting.

Abstract: Methods and apparatus are provided for handling of non-integrity reject message in the 5G system. In one novel aspect, the UE upon receiving the reject message via one access without integrity protection, retries one or more other accesses for one or more times before treating the rejection genuine. In one embodiment, the UE attempts the same 5GMM procedure over another access in the same cell/tracking area (TA). The alternative access including other types of 3GPP access and non-3GPP access. Subsequently, the UE can search the service from another cell/TA or another PLMN. In one embodiment, if the UE receives reject cause invalidating the UE with one access without integrity protection, the UE tries the system a few times before treating the reject genuine by tracking an invalidating counter, which is increased by one each time the rejection is received with a cause value invalidating the UE.

Abstract: A User Equipment (UE) including a wireless transceiver and a controller is provided. The controller obtains information indicating that the UE is not allowed to access a 3GPP core network over which one or both or none of the 3GPP access network and the non-3GPP access network. Also, the controller refrains the UE from accessing the 3GPP core network over the indicated one or both of the 3GPP access network and the non-3GPP access network in response to the information indicating that the UE is not allowed to access the 3GPP core network over one or both of the 3GPP access network and the non-3GPP access network.

Abstract: Various examples pertaining to improvement for incorrect key set identifier (KSI) handling in mobile communications are described. An apparatus (e.g., user equipment) receives from a wireless network an authentication challenge after the processor having completed an authentication and key agreement (AKA) procedure with the wireless network. The apparatus detects an error in the authentication challenge and handles the error in the authentication challenge. For example, the apparatus can reject the authentication challenge responsive to detecting the error. Alternatively, the apparatus can accept the authentication challenge.

Abstract: A User Equipment (UE) including a wireless transceiver, a storage device, and a controller is provided. The wireless transceiver performs wireless transmission and reception to and from a 5G network. The storage device includes a data space specific for 5G System (5GS) location information. The controller obtains the 5GS location information by communicating with the 5G network via the wireless transceiver, and stores the 5GS location information in the data space of the storage device.

Abstract: A User Equipment (UE) including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception to and from a service network. The controller transitions the UE from a Radio Resource Control (RRC) idle state to an RRC connected state, and after transitioning the UE from the RRC idle state to the RRC connected state, sends an initial Non-Access Stratum (NAS) message comprising a limited set of Information Elements (IEs) in cleartext, which are required to establish security between the UE and the service network, and a container IE carrying an initial NAS message Protocol Data Unit (PDU) ciphered with NAS security context to the service network via the wireless transceiver.

Abstract: Various examples pertaining to an improved TAU procedure for intersystem change in mobile communications are described. A user equipment (UE) establishes a wireless communication connection with a first wireless network of a first type of wireless communication system. The UE then performs an intersystem change from being connecting to the first wireless network to being connected to a second wireless network of a second type of wireless communication system different from the first type. In performing the intersystem change, the UE constructs a tracking area update (TAU) request message and transmits the TAU request message to the second wireless network. The TAU request message identifies the UE.

Abstract: A User Equipment (UE) including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception to and from a first service network utilizing a first Radio Access Technology (RAT) and a second service network utilizing a second RAT. The controller starts a Mobility Management (MM) back-off timer in response to a first MM procedure with the first service network being rejected, determines whether both the UE and the first service network support a dual registration mode in response to starting the MM back-off timer, and initiates a second MM procedure with the second service network via the wireless transceiver when the MM back-off timer is running, in response to determining that both the UE and the first service network support the dual registration mode.

Abstract: Various examples pertaining to application of non-access stratum (NAS)-level congestion control timer values at intersystem change in mobile communications are described. A user equipment (UE) receives an indication of a NAS-level congestion control from a first type of wireless network. The UE starts a timer responsive to the receiving of the indication of the NAS-level congestion control. The UE then performs an intersystem change from the first type of wireless network to a second type of wireless network different from the first type by utilizing the timer.

Abstract: A method of supporting reception of standalone SERVICE ACCEPT message is proposed. In one embodiment, a new timer is started when the UE determines successful completion of the service request procedure and has not received SERVICE ACCEPT during the procedure. In an alternative embodiment, an existing timer T3417 or T3417ext can be used to define the allowed time window for the reception of SERVICE ACCEPT. While the timer is running, the UE can treat the SERVICE ACCEPT message as successfully received and the message does not cause protocol error.

Abstract: Aspects of the disclosure provide a method for handling reject in wireless communication. The method includes receiving, at an electronic device, a reject message indicative of a forbidden resource of a service provider network to use by the electronic device for wireless communication, determining a reliability attribute of the reject message, storing the forbidden resource associated with the reliability attribute, and maintaining the stored forbidden resource based on the reliability attribute.

Abstract: Various solutions to handling of registration rejects with respect to user equipment (UE) in mobile communications are described. A UE may transmit a first request to a first network element of a wireless network. The UE may receive a first reject from the first network element. The UE may bar the first network element in response to receiving the first reject from the first network element. The UE may transmit a second request to a second network element of the same wireless network or a different wireless network in response to receiving the first reject from the first network element. Alternatively, the UE may transmit a second request to the first network element after a period of barring time.