A base station transmits to a wireless device, a first request to measure synchronization signal(s) of a first cell. The base station receives from the wireless device, measurement report(s) of at least one synchronization signal of the synchronization signal(s). The base station transmits to the wireless device, a second request to measure CSI-RS(s) of the first cell. The base station receives from the wireless device, second measurement report(s) of the CSI-RS(s). The second measurement report(s) are generated in response to the second request. The base station selects first CSI-RS(s) of the CSI-RS(s) based on the second measurement report(s). The base station transmits a downlink control information to the wireless device via one or more control channels. The downlink control information initiates a random access procedure of the first cell. The downlink control information comprises an indication of the first CSI-RS(s).

Systems and methods for specifying UE power control allocation for simultaneous transmission of PRACH in a secondary serving cell and PUCCH/PUSCH/SRS in a different serving cell in another timing advance group are disclosed. Rules are provided for prioritizing transmission of PRACH and/or other UL channels/signals. Additionally, UE power allocation is controlled for misaligned subframes across different timing advance groups. Latency of UL synchronization for a secondary serving cell is reduced by prioritizing PRACH retransmission.

The present invention relates to methods and apparatuses radio base station (120, 600) and UE (110, 700) for enabling a UE to perform a random access. According to embodiments of the present invention, an identification number of a dedicated random access preamble is, in a message, transmitted together with information indicating in which channel or channels the preamble is valid for the UE. The UE (110, 700) can then use the received information and based on that information perform a random access.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a network node via a source cell, a medium access control (MAC) control element (MAC-CE) triggering a handover from the source cell to a target cell in an activated cell set configured for Layer 1/Layer 2 (L1/L2) mobility. The UE may transmit, to the network node via the target cell, a physical random access channel (PRACH) to initiate an aperiodic contention-free random access (CFRA) procedure in the target cell in a random access channel (RACH) occasion in a PRACH slot associated with a slot offset indication received from the network node. Numerous other aspects are described.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a network node via a source cell, a medium access control (MAC) control element (MAC-CE) triggering a handover from the source cell to a target cell in an activated cell set configured for Layer 1/Layer 2 (L1/L2) mobility. The UE may transmit, to the network node via the target cell, a physical random access channel (PRACH) to initiate an aperiodic contention-free random access (CFRA) procedure in the target cell in a random access channel (RACH) occasion in a PRACH slot associated with a slot offset indication received from the network node. Numerous other aspects are described.

Embodiments of the present disclosure relate to methods and apparatus for beam maintenance in a radio access network, in particular, through random access preamble transmission for beam maintenance. A terminal device receives, from a network device, a resource configuration for contention-free random access. The resource configuration indicates a plurality of CFRA resources each associated with a respective synchronization signal and physical broadcast channel block index or channel state information reference signal index. The plurality of CFRA resources are applicable for timing advance acquiring in a target network device. The terminal device transmits, to the target network device, one or more CFRA physical random access channels based on the resource configuration. In this way, beam maintenance may be performed based on an SSB index or CSI-RS index associated with one of the transmitted CFRA PRACH(s) before a cell switch command or a random access response.

Embodiments of the present disclosure relate to methods and apparatus for beam maintenance in a radio access network, in particular, through random access preamble transmission for beam maintenance. A terminal device receives, from a network device, a resource configuration for contention-free random access. The resource configuration indicates a plurality of CFRA resources each associated with a respective synchronization signal and physical broadcast channel block index or channel state information reference signal index. The plurality of CFRA resources are applicable for timing advance acquiring in a target network device. The terminal device transmits, to the target network device, one or more CFRA physical random access channels based on the resource configuration. In this way, beam maintenance may be performed based on an SSB index or CSI-RS index associated with one of the transmitted CFRA PRACH(s) before a cell switch command or a random access response.

A method of performing a beam management in a wireless communication system and a device therefor are disclosed. The method performed by a user equipment (UE) comprises receiving, from a base station (BS), configuration information including i) resource information on a plurality of reference signals and ii) candidate beam determination algorithm information, determining N candidate beams for at least one serving beam based on the candidate beam determination algorithm information, the N candidate beams being related to N reference signals of the plurality of reference signals, receiving, from the BS, the N reference signals of the plurality of reference signals based on the resource information on the plurality of reference signals, and transmitting, to the BS, measurement information including at least one measurement value among the N reference signals.

A method of performing a beam management in a wireless communication system and a device therefor are disclosed. The method performed by a user equipment (UE) comprises receiving, from a base station (BS), configuration information including i) resource information on a plurality of reference signals and ii) candidate beam determination algorithm information, determining N candidate beams for at least one serving beam based on the candidate beam determination algorithm information, the N candidate beams being related to N reference signals of the plurality of reference signals, receiving, from the BS, the N reference signals of the plurality of reference signals based on the resource information on the plurality of reference signals, and transmitting, to the BS, measurement information including at least one measurement value among the N reference signals.

A beam failure recovery method and a communication apparatus are provided. The method includes: A terminal device initiates a random access process when detecting that a beam failure occurs on all M TRPs associated with a special cell; determines available beams of N TRPs in the M TRPs, where 1<N?M, and M and N are integers; and sends first information to a network device in the random access process, where the first information indicates information about the available beams of the N TRPs, and each of the N TRPs corresponds to one available beam. After receiving the first information, the network device returns a random access response message to the terminal device.