Abstract: Systems and methods are disclosed for performing random access (RA) in 5G New Radio (NR) systems, including New Radio in unlicensed spectrum (NR-U) systems. A wireless transmit/receive unit (WTRU) may receive a configuration for physical random access channel (PRACH) resources. The WTRU may determine whether to use a first type of PRACH transmission or a second type of PRACH transmission. For the first type of PRACH transmission, the WTRU may select a PRACH resource, without performing listen-before-talk (LBT), immediately following reception of an synchronization signal block (SSB). For the second type of PRACH transmission, the WTRU may randomly select the PRACH resource associated with the SSB, and perform a first LBT on the selected PRACH resource. The WTRU may transmit a PRACH preamble in the selected PRACH resource. The WTRU may perform a second LBT for random access response (RAR) reception for hidden node detection.

Abstract: Systems, methods, and instrumentalities are disclosed herein associated with physical random access, e.g., for new radio (NR) implementations such as NR-unlicensed (NR-U). A wireless transmit/receive unit (WTRU) may switch a position of a PRACH occasion (RO) with another RO to reduce latency (e.g., so that a WTRU can transmit a preamble without performing a LBT operation). Systems, methods, and instrumentalities are disclosed for reserving a listen-before-talk (LBT) procedure gap at the beginning of a random access channel (RACH) occasion (RO) in New Radio (NR) unlicensed (NR-U) systems. The present systems, methods, and instrumentalities may (e.g., may also) be applied to consecutive ROs. This may include reserving a LBT gap for example, for a RO transmission (e.g., for each of the consecutive ROs). Low latency RACH for NR-U systems may be supported (e.g., mapping rules for the RO may be implemented).

Abstract: Random access may be provided for integrated access and backhaul (IAB) for New Radio (NR). A wireless transmit/receive unit may send (e.g., to a gNB) a preamble in a random access occasion (RO). One or more of the preamble or an RO resource partition of the RO may indicate a node type of the WTRU. The WTRU may receive (e.g., from the gNB) a physical downlink control channel (PDCCH) that indicates (e.g., includes) one or more random access responses (RARs). The WTRU may determine that the PDCCH indicates a WTRU RAR and an integrated access and backhaul (IAB) node RAR. If the sent node type is a WTRU node type, the WTRU may receive (e.g., from the gNB) the WTRU RAR at a first time and frequency location indicated by the PDCCH.

Abstract: Systems and methods are disclosed for performing random access (RA) in 5G New Radio (NR) systems, including New Radio in unlicensed spectrum (NR-U) systems. A wireless transmit/receive unit (WTRU) may receive a configuration for physical random access channel (PRACH) resources. The WTRU may determine whether to use a first type of PRACH transmission or a second type of PRACH transmission. For the first type of PRACH transmission, the WTRU may select a PRACH resource, without performing listen-before-talk (LBT), immediately following reception of an synchronization signal block (SSB). For the second type of PRACH transmission, the WTRU may randomly select the PRACH resource associated with the SSB, and perform a first LBT on the selected PRACH resource. The WTRU may transmit a PRACH preamble in the selected PRACH resource. The WTRU may perform a second LBT for random access response (RAR) reception for hidden node detection.

Abstract: Random access may be provided for integrated access and backhaul (IAB) for New Radio (NR). A wireless transmit/receive unit may send (e.g., to a gNB) a preamble in a random access occasion (RO). One or more of the preamble or an RO resource partition of the RO may indicate a node type of the WTRU. The WTRU may receive (e.g., from the gNB) a physical downlink control channel (PDCCH) that indicates (e.g., includes) one or more random access responses (RARs). The WTRU may determine that the PDCCH indicates a WTRU RAR and an integrated access and backhaul (IAB) node RAR. If the sent node type is a WTRU node type, the WTRU may receive (e.g., from the gNB) the WTRU RAR at a first time and frequency location indicated by the PDCCH.

Abstract: Systems, methods, and instrumentalities are disclosed herein associated with physical random access, e.g., for new radio (NR) implementations such as NR-unlicensed (NR-U). A wireless transmit/receive unit (WTRU) may switch a position of a PRACH occasion (RO) with another RO to reduce latency (e.g., so that a WTRU can transmit a preamble without performing a LBT operation). Systems, methods, and instrumentalities are disclosed for reserving a listen-before-talk (LBT) procedure gap at the beginning of a random access channel (RACH) occasion (RO) in New Radio (NR) unlicensed (NR-U) systems. The present systems, methods, and instrumentalities may (e.g., may also) be applied to consecutive ROs. This may include reserving a LBT gap for example, for a RO transmission (e.g., for each of the consecutive ROs). Low latency RACH for NR-U systems may be supported (e.g., mapping rules for the RO may be implemented).