A wireless device may receive various control messages from a base station for cell switching. These control messages may indicate timing information and configure the wireless device to switch from a source cell to a target cell. If timing information is not indicated, the wireless device may measure timing information and/or skip a random-access procedure for the target cell.

A method of a terminal for a RACH-less handover may comprise: receiving, from a source cell, information on a UL grant for UL transmission in a target cell, the information on the UL grant including a start time and an expiration time of the UL grant and/or a maximum number of transmissions according to the UL grant; performing transmission of an RRC reconfiguration complete message using resources indicated by the UL grant from the start time, until the expiration time or until the transmission is completed up to the maximum number of transmissions from the start time; and in response to the transmission of the RRC reconfiguration complete message not being successful until the expiration time or until the transmission is completed up to the maximum number of transmissions, performing a fallback procedure for the RACH-less handover.

An enhanced connection recovery upon lost RRC connection due to radio link failure (RLF) or handover failure (HOF) is proposed. A UE first establishes an RRC connection in a source cell in a mobile communication network. Later on, the UE detects a failure event and starts an RRC reestablishment procedure in a target cell to restore the RRC connection. In a first novel aspect, a fast RLF process is applied to reduce the outage time in the serving cell. In a second novel aspect, an enhanced cell selection mechanism based on cell prioritization information is applied to reduce the outage time in the target cell. In one embodiment, multi-RAT registration is used to steer cell selection.

A method and system for pre-configuring a UE with timing advance for use in communication with a handover target. When a UE is being served by a handover source, the handover source transmits to a handover target a measurement request that specifies an uplink reference signal that the UE will provide, and the handover target evaluates that uplink reference signal to determine a timing advance for the UE and reports the timing advance in a response to the handover source. As the handover source then directs the UE to hand over to the handover target, the handover source provides the UE with an indication of the timing advance provided by the handover target. The UE may then transition to be served by the handover target and to make use of the indicated timing advance.

A method and an apparatus for synchronized handover in a mobile communication system are provided. A source base station providing data to a terminal transmits a handover command message for handover to a target base station to the terminal, and interrupts transmission of data to the terminal when the source base station receives a message for informing a handover execution timing from the terminal later. In addition, the source base station forwards data on the terminal to the target base station.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a base station may determine to transmit a pre-allocated uplink (UL) grant to a user equipment (UE), wherein the pre-allocated UL grant includes: a secondary node (SN) transmission configuration indicator (TCI) list, and a type 1 configured grant (CG). The base station may transmit, to the UE, the pre-allocated UL grant based at least in part on determining to transmit the pre-allocated UL grant. Numerous other aspects are provided.

The present disclosure relates to a communication method and system for converging a 5.sup.th-Generation (5G) communication system for supporting higher data rates beyond a 4.sup.th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The present disclosure relates to handover performed without random access in a wireless communication system.

A method for reporting assistance information, a method for configuring reporting of assistance information, a terminal, and a network side device. The method for reporting assistance information is applicable to a terminal and includes: reporting assistance information of the terminal to a target cell in a dual connectivity mobility process, where in the dual connectivity mobility process, the terminal maintains connections to a source cell and the target cell simultaneously.

The present invention is about conditional handover (CHO) in telecommunications networks, and a main point is to pass the responsibility to a target Master Node for triggering the UE to rapid access to Primary Secondary Cell after applying target Primary Cell configuration during a CHO-NR-DC handover. The target MN decides whether to wait further to execute CPC. If measurements are hopeful, completion of execution of the primary secondary cell for dual connectivity is postponed, and L3 measurement results are inspected from the UE. There are three variants, when the target MN requests the UE to access the target Secondary Node; namely RRC-based access target SN trigger, PDCCH-order-based variant and DL MCE-based variant.

In this invention, when a serving distributed unit informs target distributed unit via a central unit about a target reference, it is proposed to use, signal index X/indices X1 . . . Xn for PDCCH transmissions or PUSCH receptions or a RACH-less handover:

Send by a distributed unit of the serving cell towards a distributed unit of a target cell one of before, upon, or after transmission of a layer 1 serving cell change command to a user equipment, signaling comprising configuration information associated with the user equipment to perform a random access channel less handover of the user equipment to the target cell, wherein the configuration information informs the target cell about at least one target reference signal index that shall be used for at least one of at least one physical downlink control channel transmission or at least one physical uplink shared channel reception.