A solution for security negotiation during handover of a user equipment (UE) between different radio access technologies is provided. In the solution, the UE receives non-access stratum (NAS) security information and access stratum (AS) security information which are selected by the target system and then performs security negotiation with the target system according to the received NAS security information and AS security information. As such, the UE may obtain the key parameter information of the NAS and AS selected by a Long Term Evolution (LTE) system and perform security negotiation with the LTE system when the UE hands over from a different system, such as a Universal Terrestrial Radio Access Network (UTRAN), to the LTE system.

A device searches for a primary access network, and acquires the primary access network. The device also requests a service provided by a network connected to the primary access network, and attaches to the primary access network only when the service is requested by the device.

A method, at a user equipment (UE), the method: sending a request to a first network for Circuit Switched Fallback (CSFB); receiving, responsive to the request, redirection information; acquiring a second network based on the redirection information; initiating establishment of Circuit Switched (CS) voice radio bearers with the second network; waiting for a predetermined event to occur; after the predetermined event has occurred, establishing a Packet Switched (PS) connection with the second network. Further, a method, at a network element, the method receiving a request for Circuit Switched Fallback (CSFB) from a user equipment (UE); sending, to the UE, redirection information; receiving a Routing Area Update (RAU) message from the UE; waiting for a predetermined event to occur; upon the predetermined event occurring, responding to the RAU message.

Embodiments of the present invention provide a method, apparatus, and system for a handover to a circuit switched domain. The method includes: selecting an MSC capable of both CSFB and SRVCC for a UE; and selecting, if a location service of a CS domain triggers an SRVCC procedure for the UE when the UE has a VOIP service in progress, the MSC capable of both CSFB and SRVCC in the SRVCC procedure, so that the UE, after being handed over to the CS domain, accesses the MSC and implements the location service of the CS domain. The apparatus includes: a first selecting module and a second selecting module. The system includes a UE and the apparatus. The embodiments of the present invention enable the UE with the VOIP service in progress to be correctly handed over to the CS domain and implement the location service.

Various solutions for avoiding circuit-switched call drop with respect to user equipment and network apparatus in mobile communications are described. An apparatus transmits a non-access stratum (NAS) message in a NAS signaling connection. The apparatus receives a NAS response message. The apparatus initiates a timer to control the NAS signaling connection. The apparatus further receives a circuit-switched (CS) service notification. The apparatus then stops the timer and execute a CS service procedure.

Systems and methods may provide at least one service to a user equipment in an IP network subsystem supporting packet based services, wherein the user equipment is operating in a voice centric mode. Embodiments may receive a broadcast of at least one information of the IP network subsystem through at least one system information message, determine a network capability information at the user equipment based on the at least one information of the IP network subsystem, switch the user equipment from the voice centric mode to a data centric mode, wherein in the data centric mode, the user equipment is subscribed to receive the packet based services, latch the user equipment with the IP network subsystem when one of an over the top and a rich communication service allows the latching, and receive the at least one service at the user equipment via one of the over-the-top and the rich communication services.

There is provided a method comprising: determining that at least one channel condition of a first carrier is below a threshold, the first carrier operating as a first primary carrier and having a first bandwidth; in response to the determining, determining to use a second carrier as a second primary carrier, which second carrier is determined to provide better coverage than the first carrier, wherein the second carrier comprises a narrowband single resource block co-located within the first bandwidth; and receiving a control channel using the second carrier.

It is presented a method for error handling during a Mobile Terminated, MT, call to a User Equipment, UE, in a cellular system. The method is performed by a network device being an alternative Mobility Management Entity, MME, of the cellular system. The method comprises the steps of: failing to forward a paging request to a serving MME, at which the UE is registered; and paging the UE using a Circuit Switched, CS, paging. A corresponding network device, User Equipment, computer program and computer program product are also presented.

A method in a wireless communication device for starting a Circuit Switched FallBack, CSFB, in a wireless communication system is disclosed. The wireless communication system comprises one or more Long-Term Evolution, LTE, networks and one or more 2nd or 3rd Generation, 2G/3G, networks. When the communication device is camping in an LTE network and starts a Circuit Switched, CS, service, the wireless communication device sends a CSFB request to a Mobility Management entity, MME, via an access node in the LTE network and starts a first timer and/or a first counter upon sending the CSFB request. When the first timer and/or the first counter is expired and no response to the CSFB request has been received from the LTE networks, it starts a cell search procedure in the 2G/3G networks and starts the CS service via a target cell selected by the cell search procedure in the 2G/3G networks.

A method using multiple receivers of a wireless communication device to accelerate cell selection and reselection is disclosed. Multiple receivers of the wireless device are used to implement carrier aggregation in LTE connected mode. The multiple receivers of the wireless device are used to search for cells concurrently across multiple radio frequency bands and/or multiple radio access technologies during cell selection and/or cell reselection procedures. A first receiver and a second receiver of the wireless device each search for cells over different radio frequency bands simultaneously, and accordingly the cell selection and reselection time is effectively reduced compared to using only one receiver. Multiple receivers are also used concurrently, in parallel, to accelerate inter-frequency cell detection and measurement and for inter-RAT searches and measurements.