Patent Description:
3GPP contribution <NPL> discusses issues on the channel structure for <NUM>-step RACH, including mapping between PRACH and PUSCH, additional validation rule for msgA PUSCH, scrambling for msgA PUSCH DMRS. 3GPP contribution <NPL>, discusses the channel structure for <NUM>-step RACH, including mapping between PRACH and PUSCH, configuration for msgA, validation rule for msgA PUSCH, scrambling for msgA PUSCH and DMRS sequence generation for msgA PUSCH.

The invention relates to a method of wireless communication performed by a user equipment, the corresponding user equipment and computer program as defined in the appended independent claims. Embodiments representing particular realisations of the invention are defined in the appended dependent claims.

The BSs may also communicate with one another (directly or indirectly) via a wireless or wireline backhaul.

For example, the UEs <NUM> may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, vehicle-to-pedestrian (V2P) protocol, and/or the like), a mesh network, and/or the like.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with using an extended demodulation reference signal (DMRS) scrambling identifier for DMRS communication, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. In some aspects, memory <NUM> and/or memory <NUM> may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors of the base station <NUM> and/or the UE <NUM>, may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein.

In some aspects, UE <NUM> may include means for receiving, from a base station (e.g., BS <NUM>), information identifying a quantity of DMRS sequences supported per antenna panel of the BS or means for transmitting a DMRS communication having one or more DMRS sequences configured based at least in part on the quantity of DMRS sequences supported per antenna panel and scrambled using an extended DMRS scrambling identifier that is based at least in part on a physical random access channel preamble, among other examples. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>, such as controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like.

<FIG> is a diagram illustrating an example <NUM> of a channel structure for transmitting a physical random access channel (PRACH) message type A (msgA), in accordance with various aspects of the present disclosure.

As shown in <FIG>, a channel structure for transmitting a PRACH msgA may include resources allocated for a preamble section (msgA Preamble) and a payload section (msgA payload). The preamble section, which may include a cyclic prefix (CP), is in time and frequency resources allocated for PRACH transmission (TPRACH). After the time resources allocated for the PRACH transmission, the channel structure may include time and frequency resources allocated as a guard period and/or a gap period (TG,<NUM> and Tgap,<NUM>, respectively) to enable transitioning of a transmit chain from msgA preamble transmission to msgA payload transmission. As shown, the msgA payload section may include a DMRS transmission that is multiplexed with a physical uplink shared channel (PUSCH) transmission, as described in more detail herein. The msgA payload section may include a guard period (TG,<NUM>) to enable a UE to transition from transmitting the PRACH msgA to transmitting another communication or receiving a communication.

<FIG> is a diagram illustrating an example <NUM> of a resource mapping for transmitting a PRACH msgA, in accordance with various aspects of the present disclosure.

As shown in <FIG>, a msgA transmission occasion may include time resources and frequency resources that map to a synchronization signal block (SSB) of a set of SSBs. The msgA transmission occasion may occur in an initial or an active uplink bandwidth part (BWP) and may include a random access channel (RACH) slot with a set of RACH occasions (ROs). Further, the msgA transmission occasion may include one or more different types of PUSCH configurations, such as an msgA PUSCH configuration #<NUM> and an msgA PUSCH configuration #<NUM>.

In some aspects, a BS may configure, when a UE is in a radio resource control (RRC) idle state or an RRC inactive state, a first set of two different transport block sizes (TBSs) for the msgA PUSCH in a system information. The first set of two different TBSs may be configured for transmission in an initial BWP. In contrast, the BS may configure, when the UE is in an RRC connected state, a second set of two different TBSs for the msgA PUSCH. In this case, the BS may configure the second set of TBSs in RRC signaling for an active bandwidth part (e.g., which may be the same or different from the initial bandwidth part). Based at least in part on receiving information identifying a set of transport block sizes from the BS, the UE may select a particular TBS based at least in part on a layer <NUM> reference signal received power (RSRP) measurement, a content of a msgA data buffer, a satisfaction of a msgA group size parameter, and/or the like.

<FIG> is a diagram illustrating an example <NUM> of a transmit chain for transmitting a PRACH msgA, in accordance with various aspects of the present disclosure.

As shown in <FIG>, a UE, such as UE <NUM>, may include a transmit chain for transmitting msgA. In this case, the UE may receive, at the transmit chain, a payload and cyclic redundancy check (CRC) and may perform channel coding and rate matching on the payload and CRC to generate bits for transmission. After performing channel coding and rate matching, the UE may use a scrambling sequence to scramble bits of the payload and CRC. For example, the bit scrambling module may use a scrambling sequence of the form: <MAT> where Cinit represents an initial value of the scrambling sequence, RA-RNTI is a random access (RA) radio network temporary identifier (RNTI), and nID represents an initialization value based at least in part on a UE identifier.

As further shown in <FIG>, based on scrambling bits, the UE may perform linear modulation and, in some cases, transform precoding, as described in more detail herein. After linear modulation (and transform precoding, in some cases), the UE may perform inverse fast-Fourier-transform (IFFT) processing. After IFFT processing, the UE may multiplex a DMRS with the payload and CRC (e.g., symbols generated based at least in part on bits thereof). After multiplexing the DMRS with the payload and the CRC, the UE may perform radio resource mapping to generate a msgA preamble based at least in part on a PRACH preamble and a msgA payload based at least in part on the payload and CRC and the DMRS.

A UE may generate the DMRS for multiplexing with content of msgA using a DMRS scrambling identifier. The UE may determine the DMRS scrambling identifier based at least in part on a waveform of a corresponding physical uplink shared channel (PUSCH) of the msgA. In contention based random access (CBRA)-based two-step random access channel (RACH) procedures, using a DMRS scrambling identifier based at least in part on a PUSCH waveform (e.g., a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) waveform or a cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) waveform) may result in a collision between different DMRSs. This may result in dropped communications, reduced throughput, and/or the like.

Thus, some aspects described herein enable the UE to use an extended DMRS scrambling identifier, for a DMRS, that is determined based at least in part on a scrambling identifier for a msgA PUSCH that is to be multiplexed with the DMRS. For example, the UE may determine the extended DMRS scrambling identifier based at least in part on the PRACH preamble, as shown. In this way, by reusing the PRACH preamble for determining the extended DMRS scrambling identifier, the UE reduces a likelihood of collision with increasing a processing and/or memory utilization associated with using other types of dedicated DMRS scrambling identifier for various waveforms.

In some aspects, the UE may determine the extended DMRS scrambling identifier based at least in part on the quantity of DMRS sequences that are supported per antenna panel of the BS. In some aspects, the UE may map the PRACH preamble to a PUSCH resource unit (PRU) to determine the extended DMRS scrambling identifier and perform a DMRS generation procedure. In this way, the UE may generate an extended DMRS scrambling identifier that reduces a likelihood of collision during CBRA-based two-step RACH.

<FIG> is a diagram illustrating an example <NUM> of using an extended DMRS scrambling identifier for DMRS communication, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> includes a BS <NUM> in communication with a UE <NUM>.

As further shown in <FIG>, and by reference number <NUM>, UE <NUM> receives information identifying the quantity of DMRS sequences supported per antenna panel of BS <NUM>. For example, BS <NUM> may transmit information identifying the quantity of DMRS sequences supported per antenna panel to a group of UEs <NUM> that includes the UE. In some aspects, UE <NUM> may receive DMRS sequence configuration information from BS <NUM> based at least in part on BS <NUM> configuring one or more DMRS sequences for a DMRS communication (e.g., by using a 'msgA-ScramblingID0' parameter or a 'msgA-ScramblingID1' parameter, or by configuring one or more additional DMRS positions, among other examples). In this case, BS <NUM> may configure the one or more DMRS sequences based at least in part on a quantity of DMRS sequences supported per antenna panel. In some aspects, UE <NUM> may receive information indicating that BS <NUM> supports <NUM> DMRS sequences per antenna panel, <NUM> DMRS sequences per antenna panel, and/or the like. In this case, a quantity of DMRS sequences may correspond to a quantity of DMRS scrambling identifiers (e.g., extended DMRS scrambling identifiers) supported per antenna panel. In some aspects, BS <NUM> may configure the extended DMRS scrambling identifiers on a per antenna port basis and provide system information or RRC signaling to UE <NUM> to identify the configured extended DMRS scrambling identifiers.

As further shown in <FIG>, and by reference number <NUM>, UE <NUM> configures one or more DMRS sequences for a DMRS communication. UE <NUM> configures the one or more DMRS sequences based at least in part on the quantity of DMRS sequences supported per antenna panel. Additionally, or alternatively, UE <NUM> may configure the one or more DMRS sequences based at least in part on a PRACH preamble. UE <NUM> scrambles the one or more DMRS sequences using an extended DMRS scrambling identifier that is based at least in part on the PRACH preamble. In this way, UE <NUM> may reuse a scrambling identifier of a msgA PUSCH that is to be transmitted together with the DMRS communication, as described above. In some aspects, UE <NUM> may map the PRACH preamble to a PRU to reuse the scrambling identifier of the msgA PUSCH for the extended DMRS scrambling identifier.

In this case, UE <NUM> supports one or more different possible mapping ratios. UE <NUM> may determine the mapping ratio based at least in part on a quantity of PRACH sequences assigned for a msgA preamble on valid RACH occasions (ROs) and a quantity of PRUs assigned for msgA payload on valid PUSCH occasions (POs). In some aspects, UE <NUM> may determine the mapping ratio based at least in part on a received broadcast from BS <NUM> (e.g., of a system information) or via RRC signaling from BS <NUM>. Additionally, or alternatively, after validation of a msgA resource occasion and msgA RO and a msgA PO for a two-step RACH, UE <NUM> may determine the mapping ratio based at least in part on a validation rule and a mapping order (e.g., received from BS <NUM>). In the claimed embodiment, each msgA PUSCH configuration in an initial or active bandwidth part may be associated with a single mapping ratio, and different msgA PUSCH configurations have different mapping ratios. The mapping ratio may be valid for at least a mapping period between msgA ROs and msgA PUSCH POs. In this case, the mapping period may be a common multiple of an SSB to RO association pattern period for each msgA PUSCH configuration.

In some aspects, UE <NUM> may generate the DMRS communication using a particular DMRS pattern. For example, UE <NUM> may generate a type-I DMRS pattern-based DMRS, a type-II DMRS pattern-based DMRS, and/or the like.

In some aspects, UE <NUM> may determine the extended DMRS scrambling identifier based at least in part on a type of waveform for a transmission that includes the msgA PUSCH and the DMRS communication. For example, for a CP-OFDM waveform and when transform precoding is not enabled, UE <NUM> may determine the extended DMRS scrambling identifier based at least in part on an equation of the form: <MAT>.

In this case, UE <NUM> reuses the bit scrambling sequence applied to the payload and CRC of the msgA, as described above. Additionally, or alternatively, UE <NUM> may determine the extended DMRS scrambling identifier based at least in part on an equation of the form: <MAT> where l is the OFDM symbol number within a slot, ns,fµ is the slot number within a frame, and 〈·〉 is an inner quantity operator (e.g., truncating an inner quantity to K most significant bits (MSBs) or least significant bits (LSBs)). In this case, UE <NUM> determines the extended DMRS scrambling identifier based at least in part on the bit scrambling sequence, a symbol number for the DMRS, a slot number for the DMRS, and/or the like.

Additionally, or alternatively, when the waveform is a DFT-s-OFDM waveform and transform precoding is enabled, UE <NUM> may determine an extended DMRS scrambling identifier for group hopping and sequence hopping, such that: <MAT> <MAT> <MAT>.

In this case, UE <NUM> may determine <MAT> as: <MAT>.

Additionally, or alternatively, UE <NUM> may determine <MAT> as: <MAT>.

In this case, support for CP-OFDM or DFT-s-OFDM waveforms, as described above, may correspond to UE <NUM> determining whether to apply transform precoding for PUSCH transmission (e.g., using CP-OFDM may correspond to not using transform precoding, and using DFT-s-OFDM may correspond to using transform precoding).

As further shown in <FIG>, and by reference number <NUM>, UE <NUM> may transmit the DMRS communication. For example, based at least in part on configuring the DMRS sequences using the extended DMRS scrambling identifier, UE <NUM> may transmit a DMRS multiplexed with a msgA PUSCH. In this way, BS <NUM> and UE <NUM> reduce a likelihood collision between DMRSs in CBRA-based two-step RACH.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the UE (e.g., UE <NUM> and/or the like) performs operations associated with using an extended demodulation reference signal scrambling identifier for demodulation reference signal communication.

As shown in <FIG>, in some aspects, process <NUM> may include receiving, from a BS, information identifying a quantity of DMRS sequences supported per antenna panel of the BS (block <NUM>). For example, the UE (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, or controller/processor <NUM>, among other examples) may receive, from a BS, information identifying a quantity of DMRS sequences supported per antenna panel of the BS, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting a DMRS communication, with one or more DMRS sequences configured based at least in part on the quantity of DMRS sequences supported per antenna panel and scrambled using an extended DMRS scrambling identifier that is based at least in part on a physical random access channel preamble (block <NUM>). For example, the UE (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, or antenna <NUM>, among other examples) may transmit a DMRS communication, with one or more DMRS sequences configured based at least in part on the quantity of DMRS sequences supported per antenna panel and scrambled using an extended DMRS scrambling identifier that is based at least in part on a physical random access channel preamble, as described above.

In a first aspect, process <NUM> includes configuring the one or more DMRS sequences, which includes generating a waveform for the DMRS communication, where the waveform for the DMRS communication is a cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) waveform or a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) waveform.

In a second aspect, alone or in combination with the first aspect, the quantity of DMRS sequences supported per antenna panel is <NUM> or <NUM>.

In a third aspect, alone or in combination with one or more of the first and second aspects, a DMRS pattern of the one or more DMRS sequences is a Type-I DMRS pattern or a Type-II DMRS pattern.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, configuring the one or more DMRS sequences includes mapping the physical random access channel preamble to a physical uplink shared channel resource unit including the one or more DMRS sequences in connection with a mapping ratio within a mapping period between preamble and PUSCH resource unit.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the DMRS communication is associated with a physical uplink shared channel with transform precoding.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the DMRS communication is associated with a physical uplink shared channel without transform precoding.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the extended DMRS scrambling identifier is based at least in part on a physical uplink shared channel scrambling identifier of a physical random access channel message associated with the physical random access channel preamble.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the extended DMRS scrambling identifier is configured on a per antenna port basis via a system information or radio resource control transmission.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, process <NUM> may include determining the mapping ratio based at least in part on at least one of a received system information transmission from the BS, a received radio resource control transmission from the BS, a set of validation rules, or a mapping order.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, the mapping ratio is defined for a PUSCH configuration, such that each PUSCH configuration, of a plurality of PUSCH configurations, in an initial or active bandwidth part is associated with a single mapping ratio.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, a first PUSCH configuration of the plurality of PUSCH configurations is associated with a different mapping ratio than a second PUSCH configuration of the plurality of PUSCH configurations.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, the mapping period is based at least in part on a synchronization signal block to resource occasion association pattern period.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, process <NUM> may include configuring the one or more DMRS sequences for the DMRS communication based at least in part on the quantity of DMRS sequences supported per antenna panel and the physical random access channel preamble; and transmitting the DMRS communication may include transmitting the DMRS communication based at least in part on configuring the one or more DMRS sequences for the DMRS communication.

Claim 1:
A method of wireless communication performed by a user equipment, UE, comprising:
receiving (<NUM>), from a base station, BS, information identifying a quantity of demodulation reference signal, DMRS, sequences supported per antenna panel of the BS;
transmitting (<NUM>) a DMRS communication, with one or more DMRS sequences configured based at least in part on the quantity of DMRS sequences supported per antenna panel and scrambled using an extended DMRS scrambling identifier that is based at least in part on a physical random access channel preamble, and the method further comprising:
mapping the physical random access channel preamble to a physical uplink shared channel, PUSCH, resource unit including the one or more DMRS sequences in connection with a mapping ratio within a mapping period between preamble and PUSCH resource unit, wherein the mapping ratio is defined for a PUSCH configuration, such that each PUSCH configuration, of a plurality of PUSCH configurations, in an initial or active bandwidth part is associated with a single mapping ratio.