Methods, systems, and devices for wireless communications are described. The method may include receiving, from a base station over an unlicensed radio frequency spectrum band, a broadcast message including system information, the system information indicating a LBT mode of the base station and a set of random access channel resources associated with a fixed frame period, monitoring a wireless channel of the unlicensed radio frequency spectrum band during the fixed frame period for control information from the base station based on the indicated LBT mode, determining, based on the monitoring, that the base station has access to the wireless channel during the fixed frame period, and performing, based on the determining, a random access channel transmission during the fixed frame period using the set of random access channel resources.

A terminal includes a receiver that receives an index that specifies configuration information for transmitting a random access preamble; and a controller that configures, when the receiver receives additional information that specifies a time domain resource for transmitting the random access preamble and the index falls within a specific numerical range, the time domain resource specified by the additional information, the time domain resource being configured by replacing a time domain resource for transmitting the random access preamble included in the configuration information specified by the index with the time domain resource specified by the additional information.

An access point station (AP) communicates with a plurality of non-AP stations (STAs) within a synchronized transmission opportunity (S-TXOP). The S-TXOP may comprise an S-TXOP trigger followed by a plurality of S-TXOP slots. After transmission of the S-TXOP trigger, the AP may encode, for transmission within an S-TXOP slot, a downlink (DL) multi-user physical layer protocol data unit (DL MU-PPDU). The DL MU-PPDU may include a preamble followed by a data field. To indicate that a previously signaled resource unit (RU) allocation is to be used during the S-TXOP slot, the AP may encode the preamble to include an allocation ID of the previously signaled RU allocation in a signal field (SIG) of the preamble and to include a SIG-2 presence indicator to indicate that a second signal field (SIG-2) is not included in the preamble.

This disclosure provides methods, devices and systems for synchronized channel access. Some implementations more specifically relate to facilitating coexistence among wireless communication devices that support synchronized channel access and those that do not. A group of access points may schedule periodically recurring, synchronized channel access periods by periodically transmitting quiet elements. The quiet elements establish recurring quiet periods during which legacy devices are not permitted to transmit. In some implementations, an access point may transmit one or more quiet override elements each associated with a respective quiet element and indicating to other access points supporting synchronized channel access that they are permitted to contend for access during the respective quiet period. In some other implementations of synchronized channel access, an access point supporting synchronized channel access that wins contention after one or more consecutive synchronized channel access periods during which no other synchronized access points won contention, may be entitled to an extended TXOP.

A terminal including: a reception unit configured to receive configuration information for use in a random access procedure from a base station apparatus; and a transmission unit configured to transmit information indicating an attribute of the terminal to the base station apparatus in the random access procedure based on the configuration information.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a base station may generate a signal for a set of synchronization signal blocks (SSBs) for an SSB burst set, wherein the set of SSBs are associated with a set of analog beamforming configurations associated with a set of spatial directions. The base station may transmit the signal for the set of SSBs using the set of analog beamforming configurations over the set of spatial directions. The base station may receive one or more random access channel (RACH) communications corresponding to one or more SSBs of the set of SSBs in accordance with one or more frequency domain beam sweeping configurations corresponding to one or more analog beamforming configurations of the set of analog beamforming configurations. Numerous other aspects are described.

This application discloses random access methods and communication apparatuses, and relates to the field of communication technologies. In an example method, after determining a correspondence between scanning periods of different scanning areas within coverage of a synchronization signal block (SSB) beam and random access occasions (ROs), a second communication apparatus sends, through broadcasting, a first message including information about the correspondence. A first communication apparatus receives the first message, determines an RO based on a scanning area in which the first communication apparatus is located and the first message, and initiates random access.

This disclosure provides methods, devices and systems for synchronized channel access. Some implementations more specifically relate to facilitating coexistence among wireless communication devices that support synchronized channel access and those that do not. A group of access points may schedule periodically recurring, synchronized channel access periods by periodically transmitting quiet elements. The quiet elements establish recurring quiet periods during which legacy devices are not permitted to transmit. In some implementations, an access point may transmit one or more quiet override elements each associated with a respective quiet element and indicating to other access points supporting synchronized channel access that they are permitted to contend for access during the respective quiet period. In some other implementations of synchronized channel access, an access point supporting synchronized channel access that wins contention after one or more consecutive synchronized channel access periods during which no other synchronized access points won contention, may be entitled to an extended TXOP.

A method and a device for transmitting and receiving signals in a wireless communication system according to one embodiment of the present invention are characterized by transmitting a PRACH on a RO, receiving, in response to the PRACH, a PDCCH for receiving a RAR, and receiving the RAR on the basis of the PDCCH, wherein the RAR includes a portion of the bits of a frame index of the RO on which the PRACH was transmitted.

Apparatuses, methods, and systems are disclosed for random access configuration. One method includes receiving a first cell-defining synchronization signal block on a carrier. The method includes synchronizing to the first cell-defining synchronization signal block. The method includes receiving a first system information message associated with a first serving cell of the first cell-defining synchronization signal block. The first system information message includes a first random access channel configuration. The method includes receiving a bandwidth part configuration via a dedicated message from the first serving cell that indicates a bandwidth part configured with a second random access channel configuration. The method includes performing random access according to the second random access channel configuration in the bandwidth part of the first serving cell.