A method for supporting a voice service of a user equipment (UE) in a wireless communication system; and a Mobility Management Entity (MME) apparatus therefore. The method according to one embodiment includes transmitting an update location request (ULR) message to a home subscriber server (HSS); and transmitting a Notify Request message including a single radio voice call continuity (SRVCC) capability, when the MME determines that the SRVCC capability is changed. If the MME knows a homogeneity of support of an IMS voice over PS session in all TAs (Tracking areas) or all RAs (Routing Areas) related to the MME, the ULR message includes an information element. If the MME fails to know the homogeneity of support of the IMS voice over PS session due to a lack of information including Voice over IMS related capability information of the UE, the ULR message does not include the information element.

A method for supporting a voice service of a user equipment (UE) in a wireless communication system; and a Mobility Management Entity (MME) apparatus therefore. The method according to one embodiment includes transmitting an update location request (ULR) message to a home subscriber server (HSS); and transmitting a Notify Request message including a single radio voice call continuity (SRVCC) capability, when the MME determines that the SRVCC capability is changed. If the MME knows a homogeneity of support of an IMS voice over PS session in all TAs (Tracking areas) or all RAs (Routing Areas) related to the MME, the ULR message includes an information element. If the MME fails to know the homogeneity of support of the IMS voice over PS session due to a lack of information including Voice over IMS related capability information of the UE, the ULR message does not include the information element.

In one aspect, an exemplary method involves a WCD: (i) determining a likelihood of roaming, wherein the likelihood of roaming indicates a likelihood that the WCD will be handed off from a preferred coverage area to a non-preferred coverage area; and (ii) using the likelihood of roaming as a basis for managing an active set of the WCD. In particular, the WCD may manage its active set by setting at least one active-set parameter affecting the number of active sectors in an active set of the WCD, and then maintaining its active set according to the setting of the at least one active-set parameter. According to an exemplary embodiment, a WCD will make an effort to increase the number of sectors in its active set when the likelihood of roaming is greater, and vice versa.

In one aspect, an exemplary method involves a WCD: (i) determining a likelihood of roaming, wherein the likelihood of roaming indicates a likelihood that the WCD will be handed off from a preferred coverage area to a non-preferred coverage area; and (ii) using the likelihood of roaming as a basis for managing an active set of the WCD. In particular, the WCD may manage its active set by setting at least one active-set parameter affecting the number of active sectors in an active set of the WCD, and then maintaining its active set according to the setting of the at least one active-set parameter. According to an exemplary embodiment, a WCD will make an effort to increase the number of sectors in its active set when the likelihood of roaming is greater, and vice versa.

Disclosed are a message transmitting method and apparatus, and a control method and apparatus therefor for solving the problem of whether a congestion control back-off timer still running in a first PLMN is still valid in a second PLMN after a UE moves from the first PLMN to the second PLMN. The message transmitting method comprises: when it is necessary to establish a new PDU session after a UE moves from a first PLMN to a second PLMN, determining indication information of a network side; and when the UE needs to transmit a session management (SM) message in the second PLMN, determining, according to the indication information, whether a congestion control back-off timer of the UE in the first PLMN is still valid in the second PLMN.

Provided are a method and device for efficient public land mobile network (PLMN) selection upon authentication failure for each network slice in a roaming network. A user equipment (UE) receives a registration rejection message from an access and mobility management function (AMF) of a first PLMN. The registration rejection message includes rejected network slice selection assistance information (NSSAI) including first single NSSAI (S-NSSAI) and cause value #62 for the rejected NSSAI. The UE: generates second requested NSSAI including second S-NSSAI on the basis that i) the UE does not have allowed NSSAI and configured NSSAI, and ii) default configured NSSAI includes the second S-NSSAI that is not included in the rejected NSSAI and corresponds to a network slice of which the UE requests registration; and transmits a second registration request message including the second requested NSSAI to the AMF of the first PLMN.

A method is performed at a control center in a home network. The control center (CC) detects roaming of a user equipment (UE) engaged in a call across different access networks operated by different service providers and that employ different types of radio access technology (RAT) to attach to the UE. The CC identifies the different service providers and the different types of RAT associated with the different access networks. While the UE is roaming, the CC tracks different data usages for the UE on the different access networks. The CC categorizes the different data usages based on the different service providers and the different types of RAT associated with the different access networks. When the call terminates, the CC determines a total cost for data usage on the call based on the different data usages, the different types of RAT, and the different service providers.

A method is performed at a control center in a home network. The control center (CC) detects roaming of a user equipment (UE) engaged in a call across different access networks operated by different service providers and that employ different types of radio access technology (RAT) to attach to the UE. The CC identifies the different service providers and the different types of RAT associated with the different access networks. While the UE is roaming, the CC tracks different data usages for the UE on the different access networks. The CC categorizes the different data usages based on the different service providers and the different types of RAT associated with the different access networks. When the call terminates, the CC determines a total cost for data usage on the call based on the different data usages, the different types of RAT, and the different service providers.

The present invention relates to a method and a device for selecting a cell in a mobile communication system and, more particularly, to a method and a device for selecting a cell for transmitting data, by a base station, not only in a licensed frequency band but in an unlicensed frequency band. In order to achieve the described task, a method for configuring a cell of a base station in a mobile communication system according to an embodiment of the present invention comprises the steps of: connecting with a terminal through a first cell of a licensed band; transmitting, to the terminal, a message for configuring multiple second cells in an unlicensed band through the first cell; and monitoring the configured multiple second cells in the unlicensed band, wherein the number of the multiple second cells exceeds the number of cells, a Carrier Aggregation (CA) of which the terminal can support. The present disclosure relates to a 5G or a pre-5G communication system to be provided in order to support a higher data transmission rate after a 4G communication system such as an LTE.

A communications method, device, and system for solving the connection and communications efficiency problem due to the presence of a large number of cells. The method comprises: a first local controller determines that a user equipment needs to establish a data bearer; data bearer configuration information for transmitting user data is generated; the data bearer configuration information is transmitted to a first local gateway and/or at least a first small base station, so that the network element entity that has received the data bearer configuration information establishes a data transmission channel according to the data bearer configuration information, the user equipment belonging to the first local controller and the first local gateway, the first small base station providing services to the user equipment.