Patent Description:
<NPL> is a discussion and decision document focusing on Channel Structure for Two-Step <NPL> is a discussion and decision document discussing channel structure for <NUM>-step RACH.

A random access or random access channel (RACH) procedure may be performed between a user equipment (UE) and a base station in order for the UE to connect or initialize with the base station. A UE may perform a RACH procedure with the base station under many different conditions, such as, initial access to a cell provided by the base station, during a handover sequence from one cell to another, or reinitialization with the base station to re-synchronize with the base station.

A RACH procedure may include the exchange of messages between a UE and a base station. For example, one type of RACH procedure may include the exchange of four messages between the UE and the base station, and may be referred to as a "four-step RACH procedure. " Another type of RACH procedure may include the exchange of two messages between the UE and the base station, and may be referred to as a "two-step RACH procedure.

In a two-step RACH procedure the UE may send an uplink random access message in the form of a preamble portion and a payload portion to the base station to initiate the two-step RACH procedure. The base station processes the message from the UE and based on the processing results of the message from the UE, the base station may transmit a response or downlink message to the UE. However, in some instances the preamble part and the payload part may be transmitted by the UE to the base station using different transmission configurations, such that the base station may have to perform additional or multiple processing steps to process the uplink message from the UE. In addition, the response or downlink message transmitted by the base station to the UE may cause the UE to also perform additional or multiple processing steps to process the downlink message. This may lead to an increase in an implementation complexity and/or increased signaling overhead. Aspects presented herein provide a solution to the problem of increased processing steps performed by the UE and/or the base station to process a message received during a two-step RACH procedure by improving the manner in which a time-frequency resource configuration for messages in a two-step RACH procedure are configured. In some aspects, the time-frequency resource configuration for RACH messages may be optimized by defining a reference coordinate system that is utilized by both the UE and base station to determine the time-frequency resource configuration.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for determining random access messaging based on a reference subcarrier spacing (SCS) for RACH procedures. The apparatus may be a device at a UE. The device may be a processor and/or a modem at a UE or the UE itself. The apparatus receives, from a base station, random access configuration information for the base station. The apparatus determines a first time duration for a preamble of a first random access message based on the random access configuration information received from the base station and a reference SCSassociated with an uplink bandwidth part (BWP) configured for the first random access message. The apparatus determines a second time duration for a payload of the first random access message based on the random access configuration information received from the base station and the reference SCS. The apparatus transmits the first random access message to the base station to initiate a random access procedure.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a device at a base station. The device may be a processor and/or a modem at a base station or the base station itself. The apparatus transmits random access configuration information for a random access procedure to a user equipment (UE) based on a reference subcarrier spacing (SCS) associated with an uplink bandwidth part (BWP) configured for the first random access message. The apparatus receives a first random access message from the UE to initiate a random access channel (RACH) procedure. The first random access message comprising a preamble and a payload. A first time duration of the preamble and a second time duration of the payload are based on the reference SCS. The apparatus processes the first random access message. The apparatus generates a second random access response message in response to the first random access message. The apparatus transmits the second random access response message to the UE.

The third backhaul links <NUM> may be wired or wireless.

Referring again to <FIG>, in certain aspects, the UE <NUM> may be configured to utilize a reference coordinate system in the time-frequency grid to reduce signaling overhead in a two-step RACH resource configuration. For example, the UE <NUM> of <FIG> includes a determination component <NUM> configured to determine a time duration for a preamble of a first random access message based on at least a reference subcarrier spacing (SCS). The UE utilizing the reference SCS in determining the time duration for the preamble allows for a unified coordinate system to describe the time-frequency resource configuration for a two-step RACH procedure.

Referring again to <FIG>, in certain aspects, the base station <NUM>/<NUM> may be configured to provide a reference coordinate system in the time-frequency grid to reduce signaling overhead in a two-step RACH resource configuration. For example, the base station <NUM>/<NUM> of <FIG> includes a random access component <NUM> configured to transmit random access configuration information. The random access configuration information may be based on a reference SCS to allow for a unified coordinate system that may be used by the base station and UEs to describe the time-frequency resource configuration for a two-step RACH procedure.

<FIG> provide an example of slot configuration <NUM> with <NUM> symbols per slot and numerology µ=<NUM> with <NUM> slots per subframe. The slot duration is <NUM>, the subcarrier spacing is <NUM>, and the symbol duration is approximately <NUM>.

A UE may perform the two-step RACH procedure in order to acquire uplink synchronization and/or acquire an uplink grant for a network. <FIG> illustrates an example communication flow <NUM> between a UE <NUM> and a base station <NUM> as part of a two-step random access procedure. Prior to the beginning of a two-step RACH process, the UE <NUM> may receive random access configuration information <NUM> from the base station <NUM>. For example, the UE <NUM> may receive an SSB, a SIB, and/or a reference signal broadcast by the base station <NUM>. The UE <NUM> may process these signals and channels and determine the configuration for the two-step RACH. For example, the UE <NUM> may determine, at <NUM>, any of a downlink synchronization based on at least one of an SSB, SIB, or reference signal; decoding information, or other measurement information for random access with the base station <NUM>. This configuration for random access may include the messaging channel structure and other related procedures. This configuration information may be carried by the system information (SI). In some aspects, such as when the UE <NUM> is RRC connected, the configuration information for the two-step RACH procedure may be carried by both the SIB and the SSB. After the UE <NUM> obtains the configuration information, the UE <NUM> may generate and transmit a step <NUM> transmission <NUM>. The step <NUM> transmission <NUM> may comprise an uplink transmission from the UE <NUM> to the base station <NUM>. The Step <NUM> transmission <NUM> may be referred to as msgA transmission. The msgA transmission may comprise two parts, the a preamble <NUM> and a payload <NUM>. The preamble <NUM> may be transmitted first, followed by the payload <NUM>. The payload <NUM> may include some MAC-CE, RRC messaging, or data.

When the msgA arrives at the base station <NUM>, the base station <NUM> will first process the preamble <NUM>, at <NUM>, and then the payload <NUM>, at <NUM>. For example, if the processing of the preamble <NUM> is successful, the base station <NUM> may continue to the process the payload <NUM>. The base station <NUM> may then send a msgB <NUM> to the UE <NUM>. When the preamble <NUM> and payload <NUM> are successfully decoded, the msgB <NUM> transmitted by the base station <NUM> to the UE <NUM>, may include contention resolution information. The contention resolution information can comprise or be based on the UE's unique identifier.

Two-step random access may be performed in Frequency Range <NUM> (FR1) e.g., <NUM> - <NUM> and Frequency Range <NUM> (FR2) (e.g., <NUM> - <NUM>) for different cell sizes and different RRC states. For example, it may be helpful for two-step random access to be able to be performed by UEs in an RRC idle state, an RRC inactive state, and an RRC connected state. It may be helpful for two-step random access to be able to be performed for UEs having a valid timing advance (TA) and UEs without a valid TA. The numerologies used in FR1 and FR2 may be different, such that the channel propagation probabilities are also different. Thus, different time-frequency resource allocations may be used for two-step random access. As such, it may be helpful for the two-step random access to be configured to support flexible time-frequency resource allocations and flexible numerology configurations in msgA and msgB channel structure design and procedure design.

To accommodate the different propagation environments between FR1 and FR2, as well as to support different cells, there can be a transmission gap between the msgA preamble and payload.

<FIG> shows a logical channel structure of a msgA <NUM>. The msgA in diagram <NUM> includes two parts, the msgA preamble <NUM> and the msgA payload <NUM>. The msgA <NUM> further includes guard bands <NUM>. In addition, each of the preamble <NUM> and payload <NUM> may comprise a guard time <NUM> at the transmission end part. Between the preamble <NUM> and payload <NUM> is a transmission gap <NUM> (TxG). The length of the TxG <NUM> is denoted by Tg. This value of TxG <NUM> may be configurable. For example, in some aspects, such as for low latency cases, the TxG <NUM> may be set to zero. While in other aspects, such as when the preamble <NUM> and payload <NUM> use different numerologies of different bandwidth parts (BWP), they can have different power control schemes. The inclusion of the TxG <NUM> can function as a tuning gap between the preamble <NUM> and the payload <NUM>. The time duration of the preamble, the payload, and the transmission gap may be specified based on a reference SCS, which may be hardcoded or broadcast in system information (SI). For example, different reference SCS may be supported in FR1 and FR2, e.g., the reference SCS in FR1 may be <NUM>, the reference SCS in FR2 may be <NUM> or <NUM>. The actual SCS used by the preamble and/or payload is broadcast in SI or RRC, which is - according to the invention - different from the reference SCS. When the guard time and guard band are configured for payload transmission, the time duration and bandwidth may also be specified based on the reference SCS. In some aspects, the time duration of the transmission gap and guard time may be N symbols, and the BW of the guard band may be M tones.

A configurable transmission gap between the preamble and payload may be advantageous. For example, the transmission gap may account for instances where the numerology between the preamble and the payload are different. Depending on the deployment scenario, the preamble numerology may utilize a subcarrier spacing of <NUM>, <NUM>, <NUM>, or larger. As for the payload, which is mainly DMRS and PUSCH, the subcarrier spacing for the payload side numerology may be multiples of <NUM>, for example, <NUM>, <NUM>, <NUM>, <NUM>. In addition, the time frequency resource allocation may differ between the preamble and the payload. The diagram of <FIG> provides an example of a logical structure of preamble and payload, such that the preamble and payload are multiplexed together. However, in terms of time-frequency mapping, the preamble and payload may be different. For example, the preamble may occupy multiple slots and the payload may just use a faction slot. In terms of bandwidth, the preamble may occupy, for example, <NUM>, while the payload may occupy, for example, <NUM>. Also the BWP configuration for the msgA initial transmission, retransmission, or msgA fallback can be the same or different.

The resource configuration of the msgA and/or msgB may lead to some inefficiencies and/or ambiguities. Such ambiguities, for example, could result in the UE and/or the base station performing multiple and/or additional processing, which can increase the implementation complexity and, in some instances, may lead to false alarms and/or missed detections. Therefore, if may be desirable to have a reference coordinate system which may define some reference SCS or time-frequency structures in the time-frequency grid, such that the base station and UEs may use the reference coordinate system as a unified coordinate system to describe the time-frequency resource configuration. At least one advantage is that the unified coordinate system may reduce signaling overhead, as well as reduce an inefficiencies and/or ambiguities in a two-step RACH procedure. In addition, utilizing the reference SCS may reduce signaling overhead because the UE would not need to perform any calculations based on the actual SCS used instead of the reference SCS.

<FIG> is a diagram illustrating examples <NUM>, <NUM> of time-frequency resource mapping. Based on the reference SCS, the UE may know from the base station how to configure the guard bands, guard time, and the transmission gap, as well as how to index its actual transmission time. The UE may be configured to configure different time duration and different bandwidth for the preamble and the payload. If different numerology different numerologies are used, then the description may be too complicated, but if the system utilized a reference SCS, the reference slot structure can be defined as to where and when the msgA (e.g., <NUM>, <NUM>, <NUM>, <NUM>) will be transmitted in the time-frequency domain, and may also be specified in relation to the reference slot index and the reference PRB index. For example, if the network configured the UE such that it transmits at a particular frequency location and at a particular time location, so that if the UE uses a different numerology, then it may be difficult to give a unified description, but if we define some reference SCS and base it on some reference coordinate system, then where and when that UE is transmitted can be specified and related to this reference coordinates, and there won't be ambiguity for the UEs.

Based on the above, there can be a common reference point in time for slot indexing, which may inform the UE when to transmit its msgA. Specifically, when to transmit its preamble and when to transmit its payload. Those time domain locations are specified with respect to a reference slot index, and that slot index calculation is based on the reference SCS. Similarly, in frequency domain, the base station needs to tell the UE the options they can have as to how to configure the msgA channel structure in the frequency domain. The PRB indexing can also be calculated based on the reference SCS. The reference coordinate system in the time-frequency domain, the time-frequency mapping of msgA and MsgB can be specified without ambiguities. Basically, the frequency domain mapping of the msgA preamble and payload can start and end at the same or different PRB index, and occupy the same or different bandwidth, as shown in the examples <NUM>, <NUM> of <FIG>. The time domain mapping for msgA preamble and payload can also start and end at the same or diff slot index, this slot index is a reference slot index and may span a different number of slots. The slots can be an integer number of slots or fractional slot. For msgB, as shown in <FIG>, which basically includes a PDCCH part (e.g., <NUM>, <NUM>) and a PDSCH part (e.g., <NUM>, <NUM>), they can have different bandwidth and they can have different time duration. By using this reference coordinate sys, when the base station needs to tell the UE, same slot transmission, different slot transmission, same bandwidth, different bandwidth, it is made much easier because the UE and base station, when they refer to the slot index, this PRB index, they can just respect the ref SCS defined.

With reference to <FIG>, a two-step RACH UE may first select a RO and transmits its preamble on the RO (e.g., <NUM>, <NUM>). After the preamble has been transmitted, the UE may select a PRU and transmit the payload on the PRU (e.g., <NUM>, <NUM>). Depending on the deployment, payload size, and MCS, the time-frequency mapping relationship for the preamble and payload can be quite different.

<FIG> and <FIG> are related to the PUSCH resource unit (PRU) indexing and PRU grouping in accordance with certain aspects of the disclosure. In two-step RACH, each PRU may be configured with a DMRS antenna port and a DMRS sequence. The DMRS sequence may be a scrambling ID involved in DMRS sequence generation. In addition to DMRS, the PRU may also include the PUSCH time-frequency resource allocated for the PUSCH transmission.

For a given mapping rule between the preamble and PRU, the scrambling ID of the DMRS sequence generation can use the preamble sequence ID as an input parameter, as shown in <FIG>. As shown in <FIG>, the msgA payload may be patched with a CRC at <NUM>. Then, at <NUM>, the payload may be encoded by a low density parity check (LDPC) encoder, which may provide a means to control errors in data transmissions over unreliable or noisy communication channels. After that there will be some bit level scrambling, at <NUM>. Since two-step RACH needs to support UEs in all RRC states, even for UE in RRC idle states, such UEs do not have an established RRC connection with the base station yet, so it doesn't have a valid cell-radio network temporary identifier (c-mti). In view of this, some changes in the bit scrambling may be needed, because the bit scrambling may be measure by the c-mti, and that only works for RRC connected UEs. Only RRC connected UEs are permitted in a four-step RACH, but now we want to configure a two-step RACH. That means that the UE needs to transmit data the PUSCH payload part before it could obtain a valid c-rnti. In order to make the bit scrambling work and in order for the RRC idle UEs and inactive UEs to be recognized by the base station, a scrambling ID may be needed in the bit scrambling.

After the scrambling <NUM>, there is linear modulation <NUM>, and if there is any waveform, there will be transform precoding <NUM>, the transform precoding can be skipped in some instances. After that there will be IFFT <NUM> and then there will be some multiplexing with DMRS <NUM> and UCI <NUM>. Since the msgA preamble and payload are transmitted together, after the UE selects the preamble, the DMRS will not be independent. As such, there should be some association between the preamble sequence and DMRS sequence. This is because the base station will process the preamble and will use the results of processing the preamble to process the DMRS and PUSCH. If the preamble sequence and DMRS sequence are configured or generated independently, then the processing results of the preamble may not be helpful to perform the payload processing. Thus, there may be an association or mapping rule between the preamble and DMRS. Because of that these two may be correlated. After the preamble is detected, the preamble may provide sizing information for the base station to process this payload and to do the channel estimation for the UE. Due to the correlation, to generate the DMRS sequence the DMRS may use the preamble sequence index as input parameter, and this naturally is an association between the msgA preamble and the msgA payload.

For the PRU to have an index, the PRU may have a code domain index. The PRU may also have another group index. Each PRU may be configured with a DMRS antenna port and a DMRS sequence (e.g., scrambling ID), and a PUSCH time-frequency resource. For a given mapping rule between the preamble and PRU, the DMRS scrambling ID can use the preamble sequence index as an input parameter. Thus, the indexing of PRU can be done in the code domain first, based on the preamble sequence index or DMRS resource index. For example, the code index for the PRU may be defined using the following equation: <MAT>.

In the above equation, K1, K2, and K3 may be equal to or greater than zero, and are scaling integers. As shown in the formula, the preamble index becomes a parameter in generating or calculating the code index of the PRU. K1, K2, K3 are scaling integers and should be constants once the mapping rule is fixed. K1, K2, K3 and the formula can be signaled from the base station to the UE in the system info as well.

For multiple PRU, one PRU is one DMRS antenna port, DMRS sequence, and PUSCH time-frequency resource, but multiple PRUs can be multiplexed in the code domain, time domain, and frequency domain, which can translate to CDMA, TDMA, and FDMA, respectively. For multiple PRUs, which are multiplexed in the code domain the code index formula may be utilized. But multiple PRUs may be specified in the time-frequency domain, and a group index may be provided to that PRU as well. This means that across the time-frequency domain, each PRU may be specified by a <NUM>-dimensional array. The first element of the array may be the group index, so that group index can follow a frequency domain first sorting, followed by time domain sorting, or the vice-versa. In some instances, the time domain sorting may be first, followed by frequency domain sorting. The <NUM>-dimensional array identifies the PRU to be used by the UE for msgA transmission. The disclosure introduces a way to specify the PRU that is associated with a particular preamble and describes how the preamble resources and how the payload resources may be mapped and how this mapping relationship may be established based on the reference coordinate system.

<FIG> provides an example of the PRU indexing and the PRU grouping. With respect to <FIG>, the example <NUM> shows an example of multiple PRUs (e.g., <NUM>-<NUM>-<NUM>-Q) sharing a payload occasion (PO), wherein the PRUs may be ordered by code index within a PRU group (e.g., <NUM>). The example <NUM> shows multiple PRU groups (e.g., <NUM>-<NUM>) that may be configured in the time-frequency domain. The indexing of the PRU groups can follow any order disclosed herein. Each PRU may be identified my a <NUM>-dimensional array, for example, based on a PRU Group Index, and by a PRU Code Index.

<FIG> illustrate a call flow diagram <NUM> of signaling between a UE and a base station in a two-step RACH procedure in accordance with certain aspects of the disclosure. The diagram <NUM> of <FIG> include a UE <NUM> and a base station <NUM>. The base station <NUM> may be configured to provide a cell. For example, in the context of <FIG>, the base station <NUM> may correspond to base station <NUM>/<NUM> and, accordingly, the cell may include a geographic coverage area <NUM> in which communication coverage is provided and/or small cell <NUM>' having a coverage area <NUM>'. Further, a UE <NUM> may correspond to at least UE <NUM>. In another example, in the context of <FIG>, the base station <NUM> may correspond to the base station <NUM> and the UE <NUM> may correspond to UE <NUM>. Optional aspects are illustrated with a dashed line.

The UE <NUM> may perform the two-step RACH procedure in order to acquire uplink synchronization, acquire an uplink grant for a network, and/or to transmit a payload to a network. In various configurations, the UE <NUM> may indicate an identity or ID of the UE <NUM> through the two-step RACH procedure and, further, the base station <NUM> may acknowledge the ID of the UE <NUM> through the two-step RACH procedure.

Prior to the commencement of the two-step RACH procedure, the UE may receive, from the base station, random access configuration information (e.g., <NUM>) for the base station. The random access configuration information transmitted by the base station may be in the form of a downlink reference signal (RS) and/or a physical channel such as synchronization signal block (SSB) or system information block (SIB). The UE may receive and process the random access configuration information in order to determine the configuration of the two-step RACH. The random access configuration information (e.g., SSB, SIB, and RS) may include RACH process configuration parameters, such as, the channel structure of msgA and msgB for the two-step RACH process, the associated procedures, and the related thresholds. In some aspects, the random access configuration information may be based on a reference subcarrier spacing (SCS) that may be utilized as a reference to identify the time-frequency resource configuration for the messages in the two-step RACH procedure. The SCS may be predefined and known by both the UE <NUM> and the base station <NUM>. The reference SCS may be associated with an uplink BWP configured for a first random access message. In some aspects, the base station may transmit information about a reference SCS, e.g., which may be reference to as an actual SCS, <NUM>. Both the UE (e.g., <NUM>) and the base station (e.g., <NUM>) may be configured to utilize the reference SCS as a reference coordinate system that describes the time-frequency resource configuration.

A two-step RACH procedure may include the exchange of two messages between the UE <NUM> and the base station <NUM>. The UE <NUM> may initiate the two-step RACH procedure with a first random access message (e.g., <NUM>, <NUM>), which may be referred to as msgA. The msgA may include a preamble (e.g., <NUM>, <NUM>) and a payload (e.g., <NUM>, <NUM>). The base station <NUM> may complete the two-step RACH procedure with a second random access message (e.g., <NUM>), which may be referred to as msgB.

After receiving and processing the random access configuration information, the UE may generate the preamble. The UE may determine the preamble based on the configuration information indicated in the random access configuration information. The UE, at <NUM>, may be configured to determine a first time duration for the preamble (e.g., <NUM>, <NUM>) of the first random access message (e.g., <NUM>, <NUM>) based on the random access configuration information received from the base station (e.g., <NUM>) on one or multiple carrier frequencies and the reference SCS associated with an uplink BWP configured for the first random access message.

The UE may also generate the payload for the first random access message. For example, at <NUM>, the UE may be configured to determine a second time duration for the payload (e.g., <NUM>, <NUM>) of the first random access message based on the random access configuration information received from the base station on one or multiple carrier frequencies and the reference SCS.

In some aspects, the UE, at <NUM>, may be configured to determine a third time duration for a guard time (e.g., <NUM>) between the preamble (e.g., <NUM>, <NUM>) and the payload (e.g., <NUM>, <NUM>) of the first random access message. In some aspects, the third time duration of the guard time may be determined based on the random access configuration information (e.g., <NUM>) from the base station and the reference SCS. In some aspects, at least one of the preamble or the payload may comprise the guard time <NUM>. However, in some aspects, each of the preamble and the payload may comprise a guard time <NUM>. In yet some aspects, the time duration of the guard time associated with the preamble may be same or different as the time duration of the guard time associated with the payload.

In some aspects, the UE at <NUM>, may be configured to determine a bandwidth of a guard band (e.g., <NUM>) and a duration of a guard period for the first random access message based on the random access configuration information received from the base station and the reference SCS. In some aspects, at least one of the preamble or the payload may be transmitted using the guard band.

In some aspects, the UE at <NUM>, may be configured to determine a gap time duration for a transmission gap (e.g., <NUM>) between the preamble and payload based on the random access configuration information received from the base station and the referenced SCS. The transmission gap may be a duration of time between the end of transmission of the preamble and the beginning of the transmission of the payload. The duration of the transmission gap may be configurable. For example, in low latency cases, the transmission gap may be set to zero. However, in some aspects, such as when the preamble and the payload use different numerology or different bandwidth part (BWP), the preamble and payload will have different power control schemes. As such, in order for the UE to facilitate or simplify the UE transmission, a transmission gap may be introduced. The transmission gap may function as a tuning gap between the preamble and the payload. In addition, the transmission gap may also provide some advantages to the base station. For example, in two-step RACH, the base station processes the preamble first, and after the base station detects and processes the preamble, the base station will use the information derived from the processing to process the payload. The transmission gap also provides a gap in time which may simplify the base station processing.

In some aspects, the UE at <NUM>, may be configured to determine a common reference slot index for the first random access message based on the reference SCS associated with an active uplink BWP configured for the first random access message. In some aspects, a time domain mapping of the first random access message on one or multiple carrier frequencies may be based on the common reference slot index.

In some aspects, the UE at <NUM>, may be configured to determine a common reference physical resource block (PRB) for the first random access message for one or multiple carrier frequencies based on the reference SCS. In some aspects, a frequency domain mapping of the first random access message on one or multiple carrier frequencies may be based on the common reference PRB. In yet some aspects, the transmission of the first random access message may be based on at least one of the common reference slot index or the common reference PRB.

In some aspects, the UE at <NUM>, may be configured to determine at least one physical uplink shared channel (PUSCH) resource unit for the payload. The PUSCH resource unit (PRU) may be associated with a demodulated reference signal (DMRS) antenna port and a DMRS scrambling identifier (ID). The DMRS scrambling ID may be based at least on a preamble sequence index of the preamble. In some aspects, the at least one PRU may comprise a code domain index. The code domain index may be based at least on the DMRS antenna port, the DMRS scrambling ID, and the preamble sequence index.

The UE may be configured to transmit the first random access message <NUM> to the base station. The first random access message <NUM> may include the preamble <NUM> and the payload <NUM>. The UE may transmit the first random access message to the base station on one or multiple carrier frequencies to initiate the random access procedure.

The base station <NUM> may receive the first random access message from the UE on one or multiple carrier frequencies to initiate the RACH procedure. In some aspects, the first random access message may comprise the preamble and the payload, where a first time duration of the preamble and a second time duration of the payload may be based on the reference SCS.

The base station, at <NUM>, may be configured to process the first random access message. As discussed above, the preamble is processed first and then the payload. If the preamble is properly received and decoded, the base station may detect and process the payload. In some aspects, the base station may be configured to process the first random access message using a DMRS scrambling ID based on a preamble sequence index of the preamble.

The base station, at <NUM>, may generate a second random access response message in response to the first random access message. In some aspects, the second random access response message may comprise at least one of a timing advance indication or an uplink grant indication on one or multiple carrier frequencies. At least one of the timing advance indication or the uplink grant indication on one or multiple carrier frequencies may be based on the reference SCS. In some aspects, both the timing advance indication and the uplink grant indication may be based on the reference SCS. However, in some aspects, at least one of the timing advance indication or the uplink grant indication on one or multiple carrier frequencies may be based on an actual SCS (e.g., <NUM>) used in the transmission of the payload comprised in the first random access message. In yet some aspects, the timing advance indication and the uplink grant indication may be based on the actual SCS used in the transmission of the payload comprised in the first random access message. In some aspects, at least one of the timing advance indication or the uplink grant indication on one or multiple carrier frequencies may be based on a network configuration for an initial uplink BWP. In some aspects, at least one of the timing advance indication or the uplink grant indication on one or multiple carrier frequencies may be based on an active uplink BWP.

In some aspects, the base station, at <NUM>, may be configured to determine a common reference slot index for the second random access response message based on a reference SCS associated with the RACH procedure capability of the UE. In some aspects, a time domain mapping of the second random access response message may be based on the common reference slot index.

In some aspects, the base station, at <NUM>, may be configured to determine a common reference PRB for the second random access response message based on the reference SCS. In some aspects, a frequency domain mapping of the second random access response message may be based on the common reference PRB. In some aspects, the transmission of the second random access response message on one or multiple carrier frequencies may be based on at least one of the common reference slot index or the common reference PRB.

In some aspects, the second random access response message may be configured to trigger retransmission of the first random access message. For example, when the base station does not properly decode the preamble and/or the payload. In some aspects, the preamble detection and/or payload processing may be unsuccessful. In such instances, the base station is unable to successfully decode or process the preamble, as a consequence the base station may be unable to successfully perform the payload processing. Unsuccessful preamble decoding and/or unsuccessful payload processing may cause the two-step RACH procedure to fail and, therefore, the UE may reattempt the two-step RACH procedure.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a UE or a component of a UE (e.g., the UE <NUM>, <NUM>, <NUM>, <NUM>; the apparatus <NUM>/<NUM>'; the processing system <NUM>, which may include the memory <NUM> and which may be the entire UE or a component of the UE, such as the TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>). One or more of the illustrated operations may be omitted, transposed, or contemporaneous. In <FIG>, optional aspects are illustrated with a dashed line. The method may enable a UE to utilize a unified coordinate reference to describe the time-frequency resource configuration for a two-step RACH procedure.

At <NUM>, the UE may receive random access configuration information (e.g., <NUM>). For example, <NUM> may be performed by random access configuration component <NUM> of apparatus <NUM>. The UE may receive, from a base station, the random access configuration information for the base station. The random access configuration information may correspond to <NUM>, <NUM> and/or <NUM>, as described in connection with <FIG> and <FIG>.

At <NUM>, the UE may determine a first time duration (e.g., <NUM>) for a preamble (e.g., <NUM>, <NUM>) of a first random access message (e.g., <NUM>, <NUM>). For example, <NUM> may be performed by preamble time duration component <NUM> of apparatus <NUM>. The UE may determine the first time duration for the preamble of the first random access message based on the random access configuration information received from the base station on one or multiple carrier frequencies and a reference SCS common to multiple carrier frequencies. The reference SCS may be associated with an uplink bandwidth part (BWP) configured for the first random access message.

At <NUM>, the UE may determine a second time duration (e.g., <NUM>) for a payload (e.g., <NUM>, <NUM>) of the first random access message. For example, <NUM> may be performed by payload time duration component <NUM> of apparatus <NUM>. The UE may determine the second time duration for the payload of the first random access message based on the random access configuration information received from the base station on one or multiple carrier frequencies and the reference SCS. The preamble and the payload may be based on the same numerology or different numerologies. The preamble and payload may be based on the same time-frequency resource allocation or different time-frequency resource allocations. The random access configuration information may indicate information regarding the time and/or frequency allocation or numerology of the payload and the preamble with reference to the reference SCS. The reference SCS may be predefined and known to the UE and the base station. In some aspects, the base station may transmit information about the reference SCS to be used by the UE.

In some aspects, for example, at <NUM>, the UE may determine a third time duration (e.g., <NUM>) for a guard time (e.g., <NUM>) between the preamble (e.g., <NUM>, <NUM>) and the payload (e.g., <NUM>, <NUM>) of the first random access message. For example, <NUM> may be performed by guard time component <NUM> of apparatus <NUM>. The third time duration of the guard time may be determined based on the random access configuration information received from the base station and the reference SCS. In some aspects, at least one of the preamble or the payload may comprise the guard time.

In some aspects, for example, at <NUM>, the UE may determine a bandwidth (e.g., <NUM>) of a guard band (e.g., <NUM>) and a duration of a guard period (e.g., <NUM>) for the first random access message. For example, <NUM> may be performed by guard band component <NUM> of apparatus <NUM>. The UE may determine the bandwidth of the guard band and the duration of the guard period for the first random access message based on the random access configuration information received from the base station and the reference SCS. In some aspects, at least one of the preamble or the payload may be transmitted using the guard band.

In some aspects, for example, at <NUM>, the UE may determine a gap time duration (e.g., <NUM>) for a transmission gap (e.g., <NUM>) between the preamble and the payload. For example, <NUM> may be performed by gap time component <NUM> of apparatus <NUM>. The UE may determine the gap time duration for the transmission gap between the preamble and the payload based on the random access configuration information received from the base station and the reference SCS.

In some aspects, for example, at <NUM>, the UE may determine a common reference slot index (e.g., <NUM>) for the first random access message. For example, <NUM> may be performed by common reference slot index component <NUM> of apparatus <NUM>. The UE may determine the common reference slot index for the first random access message based on the reference SCS for one or multiple carrier frequencies. In some aspects, a time domain mapping of the first random access message on one or multiple carrier frequencies may be based on the common reference slot index.

In some aspects, for example, at <NUM>, the UE may determine a common reference PRB (e.g., <NUM>) for the first random access message for one or multiple carrier frequencies. For example, <NUM> may be performed by common reference PRB component <NUM> of apparatus <NUM>. The UE may determine the common reference PRB for the first random access message based on the reference SCS. In some aspects, the base station may specify a time/frequency offset between a msgA preamble occasion (RO) and a msgA payload occasion (PO) for a different numerology, a different slot format, and/or a different PO size. In some aspects, a frequency domain mapping of the first random access message on one or multiple carrier frequencies may be based on the common reference PRB. In some aspects, the transmission of the first random access message may be based on at least one of the common reference slot index or the common reference PRB.

In some aspects, for example, at <NUM>, the UE may determine at least one PRU (e.g., <NUM>) for the payload. For example, <NUM> may be performed by PRU component <NUM> of apparatus <NUM>. The at least one PRU may be associated with a DMRS antenna port and a DMRS scrambling ID. The DMRS scrambling ID may be based at least on a preamble sequence index of the preamble. In some aspects, the at least one PRU may comprise a code domain index. The code domain index may be based at least on the DMRS antenna port, the DMRS scrambling ID, or the preamble sequence index.

At <NUM>, the UE may transmit the first message (e.g., <NUM>, <NUM>) to the base station (e.g., <NUM>) on one or multiple carrier frequencies to initiate a random access procedure. For example, <NUM> may be performed by transmission component <NUM> of apparatus <NUM>.

In some aspects, for example, at <NUM>, the UE may receive, from the base station on one or multiple carrier frequencies, a second random access response message in response to the first random access message. For example, <NUM> may be performed by reception component <NUM> of apparatus <NUM>. The second random access response message may comprise at least one of a timing advance indication or an uplink grant indication. In some aspects, the time domain mapping of the second random access response message may be based on the common reference slot index. In some aspects, a frequency domain mapping of the second random access response message may be based on the common reference PRB. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on the reference SCS. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on an actual SCS used in the transmission of the payload comprised in the first random access message. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on a network configuration for an initial uplink BWP. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on an active uplink BWP. The UE may interpret the TA and/or uplink grant indication from the base station based on the reference SCS, a reference PRB index, and/or a reference slot index. The reference SCS may be predefined. In another example, the SCS may be based on the SCS used by the UE in the first random access message payload transmission. The TA and/or uplink grant indication may be based on a network configuration for an initial uplink BWP. The TA and/or uplink grant may be based on an active uplink BWP. In some aspects, a time domain mapping of the second random access response message may be based on the common reference slot index. In some aspects, a frequency domain mapping of the second random access response message may be based on the common reference PRB.

<FIG> is a conceptual data flow diagram <NUM> illustrating the data flow between different means/components in an example apparatus <NUM>. The apparatus may be a UE or a component of a UE. The apparatus includes a reception component <NUM> that may receive a second random access response message (e.g., <NUM>) in response to a first random access message (e.g., <NUM>), e.g., as described in connection with <NUM> of <FIG>. The second random access response message may comprise at least one of a timing advance indication or an uplink grant indication. The apparatus includes a random access configuration component <NUM> that may receive, from a base station (e.g., <NUM>), random access configuration information (e.g., <NUM>) for the base station, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a preamble time duration component <NUM> that may determine a first time duration (e.g., <NUM>) for a preamble (e.g., <NUM>, <NUM>) of a first random access message (e.g., <NUM>, <NUM>), e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a payload time duration component <NUM> that may determine a second time duration (e.g., <NUM>) for a payload (e.g., <NUM>, <NUM>) of the first random access, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a guard time component <NUM> that may determine a third time duration (e.g., <NUM>) for a guard time (e.g., <NUM>) between the preamble (e.g., <NUM>, <NUM>) and the payload (e.g., <NUM>, <NUM>) of the first random access message, e.g., as described in connection with <NUM> of <FIG>. The third time duration of the guard time may be determined based on the random access configuration information received from the base station and the reference SCS. The apparatus includes a guard band component <NUM> that may determine a bandwidth (e.g., <NUM>) of a guard band (e.g., <NUM>) and a duration of a guard period for the first random access message, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a gap time component <NUM> that may determine a gap time duration (e.g., <NUM>) for a transmission gap (e.g., <NUM>) between the preamble and the payload, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a common reference slot index component <NUM> that may determine a common reference slot index (e.g., <NUM>) for the first random access message, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a common reference PRB component <NUM> that may determine a common reference PRB (e.g., <NUM>) for the first random access message, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a PRU component <NUM> that may determine at least one PRU (e.g., <NUM>) for the payload, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a transmission component <NUM> that may transmit the first message (e.g., <NUM>, <NUM>) to the base station (e.g., <NUM>), e.g., as described in connection with <NUM> of <FIG>.

<FIG> is a diagram <NUM> illustrating an example of a hardware implementation for an apparatus <NUM>' employing a processing system <NUM>. The processing system <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <NUM> and the overall design constraints. The bus <NUM> links together various circuits including one or more processors and/or hardware components, represented by the processor <NUM>, the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and the computer-readable medium / memory <NUM>. The bus <NUM> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system <NUM> may be coupled to a transceiver <NUM>. The transceiver <NUM> is coupled to one or more antennas <NUM>. The transceiver <NUM> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <NUM> receives a signal from the one or more antennas <NUM>, extracts information from the received signal, and provides the extracted information to the processing system <NUM>, specifically the reception component <NUM>. In addition, the transceiver <NUM> receives information from the processing system <NUM>, specifically the transmission component <NUM>, and based on the received information, generates a signal to be applied to the one or more antennas <NUM>. The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium / memory <NUM>. The processor <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory <NUM>. The software, when executed by the processor <NUM>, causes the processing system <NUM> to perform the various functions described supra for any particular apparatus. The computer-readable medium / memory <NUM> may also be used for storing data that is manipulated by the processor <NUM> when executing software. The processing system <NUM> further includes at least one of the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The components may be software components running in the processor <NUM>, resident/stored in the computer readable medium / memory <NUM>, one or more hardware components coupled to the processor <NUM>, or some combination thereof. The processing system <NUM> may be a component of the UE <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>. Alternatively, the processing system <NUM> may be the entire UE (e.g., see <NUM> of <FIG>).

In one configuration, the apparatus <NUM>/<NUM>' for wireless communication includes means for means for receiving, from a base station, random access configuration information for the base station. The apparatus includes means for determining a first time duration for a preamble of a first random access message based on the random access configuration information received from the base station and a reference SCS associated with an uplink BWP configured for the first random access message. The apparatus includes means for determining a second time duration for a payload of the first random access message based on the random access configuration information received from the base station and the reference SCS. The apparatus includes means for transmitting the first message to the base station to initiate a random access procedure. The apparatus further includes means for determining a third time duration for a guard time between the preamble and the payload of the first random access message. The third time duration of the guard time may be determined based on the random access configuration information received from the base station and the reference SCS. The apparatus further includes means for determining a bandwidth of a guard band and a duration of a guard period for the first random access message based on the random access configuration information received from the base station and the reference SCS. The apparatus further includes means for determining a gap time duration for a transmission gap between the preamble and payload based on the random access configuration information received from the base station and the referenced SCS. The apparatus further includes means for determining a common reference slot index for the first random access message based on the reference SCS for one or multiple carrier frequencies. The apparatus further includes means for determining a common reference PRB for the first random access message for one or multiple carrier frequencies based on the reference SCS. The apparatus further includes means for receiving, from the base station on one or multiple carrier frequencies, a second random access response message in response to the first random access message. A time domain mapping of the second random access response message may be based on the common reference slot index. A frequency domain mapping of the second random access response message may be based on the common reference PRB. The apparatus further includes means for determining at least one PRU. The PRU may be associated with a DMRS antenna port and a DMRS scrambling ID. The DMRS scrambling ID may be based at least on a preamble sequence index of the preamble. The apparatus further includes means for receiving, from the base station, a second random access response message on one or multiple carrier frequencies in response to the first random access message. The second random access response message may comprise at least one of a timing advance indication or an uplink grant indication.

<FIG> is a flowchart <NUM> of a method of wireless communication. The method may be performed by a base station or a component of a base station (e.g., the base station <NUM>, <NUM>, <NUM>, <NUM>, <NUM>; the apparatus <NUM>/<NUM>'; the processing system <NUM>, which may include the memory <NUM> and which may be the entire base station or a component of the base station, such as the TX processor <NUM>, the RX processor <NUM>, and/or the controller/processor <NUM>). One or more of the illustrated operations may be omitted, transposed, or contemporaneous. In <FIG>, optional aspects are illustrated with a dashed line. The method may enable a base station to provide and/or utilize a unified coordinate reference to describe the time-frequency resource configuration for a two-step RACH procedure.

At <NUM>, the base station may transmit random access configuration information (e.g., <NUM>) for the random access procedure to a UE on one or multiple carrier frequencies. For example, <NUM> may be performed by the random access component <NUM> of apparatus <NUM>. The random access configuration information may be based on a reference SCS associated with an uplink BWP configured for the first random access message. The random access configuration information may correspond to <NUM>, <NUM> and/or <NUM>, as described in connection with <FIG> and <FIG>.

At <NUM>, the base station may receive a first random access message (e.g., <NUM>, <NUM>) from the UE (e.g., <NUM>) on one or multiple carrier frequencies to initiate a RACH procedure. For example, <NUM> may be performed by a reception component <NUM> of apparatus <NUM>. The first random access message may comprise a preamble (e.g., <NUM>, <NUM>) and a payload (e.g., <NUM>, <NUM>). The preamble may include a first time duration based on the reference SCS. The payload may include a second time duration based on the reference SCS.

At <NUM>, the base station may process the first random access message (e.g., <NUM>, <NUM>). For example, <NUM> may be performed by processor component <NUM> of apparatus <NUM>. In some aspects, processing the first random access message may include using a DMRS scrambling ID based at least on a preamble sequence index of the preamble.

In some aspects, for example, at <NUM>, the base station may determine a common reference slot index (e.g., <NUM>) for the second random access response message. For example, <NUM> may be performed by common reference slot index component <NUM> of apparatus <NUM>. The base station may determine the common reference slot index for the second random access response message based on a reference SCS associated with the RACH procedure capability of the UE. In some aspects, a time domain mapping of the second random access response message may be based on the common reference slot index.

In some aspects, for example, at <NUM>, the base station may determine a common reference PRB (e.g., <NUM>) for the second random access response message. For example, <NUM> may be performed by common reference PRB component <NUM> of apparatus <NUM>. The base station may determine the common reference PRB for the second random access response message based on the reference SCS. In some aspects, a frequency domain mapping of the second random access response message may be based on the common reference PRB. In some aspects, the transmission of the second random access response message may be based on at least one of the common reference slot index or the common reference PRB.

At <NUM>, the base station may generate a second random access response message (e.g., <NUM>) in response to the first random access message (e.g., <NUM>, <NUM>). For example, <NUM> may be performed by generation component <NUM> of apparatus <NUM>.

At <NUM>, the base station may transmit the second random access response message (e.g., <NUM>) to the UE (e.g., <NUM>) on one or multiple carrier frequencies. For example, <NUM> may be performed by transmission component <NUM> of apparatus <NUM>. In some aspects, the second random access response message may comprise at least one of a timing advance indication or an uplink grant indication. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on the reference SCS. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on an actual SCS used in transmission of the payload comprised in the first random access message. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on a network configuration for an initial uplink BWP. In some aspects, at least one of the timing advance indication or the uplink grant indication may be based on an active uplink BWP.

<FIG> is a conceptual data flow diagram <NUM> illustrating the data flow between different means/components in an example apparatus <NUM>. The apparatus may be a base station or a component of a base station. The apparatus includes a reception component <NUM> that may receive a first random access message (e.g., <NUM>) from a UE (e.g., <NUM>) to initiate a RACH procedure, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a random access component <NUM> that may transmit random access configuration information for a random access procedure to a UE, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a processor component <NUM> that may process the first random access message (e.g., <NUM>), e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a common reference slot index component <NUM> that may determine a common reference slot index (e.g., <NUM>) for the second random access response message, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a common reference PRB component <NUM> that may determine a common reference PRB (e.g., <NUM>) for the second random access response message, e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a generation component <NUM> that may generate a second random access response message (e.g., <NUM>) in response to the first random access message (e.g., <NUM>), e.g., as described in connection with <NUM> of <FIG>. The apparatus includes a transmission component <NUM> that may transmit the second random access response message (e.g., <NUM>) to the UE (e.g., <NUM>), e.g., as described in connection with <NUM> of <FIG>.

<FIG> is a diagram <NUM> illustrating an example of a hardware implementation for an apparatus <NUM>' employing a processing system <NUM>. The processing system <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <NUM> and the overall design constraints. The bus <NUM> links together various circuits including one or more processors and/or hardware components, represented by the processor <NUM>, the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and the computer-readable medium / memory <NUM>. The bus <NUM> may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system <NUM> may be coupled to a transceiver <NUM>. The transceiver <NUM> is coupled to one or more antennas <NUM>. The transceiver <NUM> provides a means for communicating with various other apparatus over a transmission medium. The transceiver <NUM> receives a signal from the one or more antennas <NUM>, extracts information from the received signal, and provides the extracted information to the processing system <NUM>, specifically the reception component <NUM>. In addition, the transceiver <NUM> receives information from the processing system <NUM>, specifically the transmission component <NUM>, and based on the received information, generates a signal to be applied to the one or more antennas <NUM>. The processing system <NUM> includes a processor <NUM> coupled to a computer-readable medium / memory <NUM>. The processor <NUM> is responsible for general processing, including the execution of software stored on the computer-readable medium / memory <NUM>. The software, when executed by the processor <NUM>, causes the processing system <NUM> to perform the various functions described supra for any particular apparatus. The computer-readable medium / memory <NUM> may also be used for storing data that is manipulated by the processor <NUM> when executing software. The processing system <NUM> further includes at least one of the components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The components may be software components running in the processor <NUM>, resident/stored in the computer readable medium / memory <NUM>, one or more hardware components coupled to the processor <NUM>, or some combination thereof. The processing system <NUM> may be a component of the base station <NUM> and may include the memory <NUM> and/or at least one of the TX processor <NUM>, the RX processor <NUM>, and the controller/processor <NUM>. Alternatively, the processing system <NUM> may be the entire base station (e.g., see <NUM> of <FIG>).

In one configuration, the apparatus <NUM>/<NUM>' for wireless communication includes means for transmitting random access configuration information for the random access procedure of the UE on one or multiple carrier frequencies. The random access configuration information may be based on a reference SCS. The apparatus includes means for receiving a first random access message from a UE on one or multiple carrier frequencies to initiate a RACH procedure. The first random access message may comprise a preamble and a payload. The preamble may include a first time duration based on the reference SCS. The payload may include a second time duration based on the reference SCS. The apparatus includes means for processing the first random access message. The apparatus includes means for generating a second random access response message in response to the first random access message. The apparatus includes means for transmitting the second random access response message to the UE on one or multiple carrier frequencies. The apparatus may further include means for determining a common reference slot index for the second random access response message based on a reference SCS associated with the RACH procedure capability of the UE. The apparatus may further include means for determining a common reference PRB for the second random access response message based on the reference SCS.

Claim 1:
A method of wireless communication at a User Equipment UE (<NUM>, <NUM>), comprising:
receiving, from a base station (<NUM>), random access configuration information for the base station (<NUM>,<NUM>, <NUM>);
determining (<NUM>) a first time duration for a preamble (<NUM>) of a first random access message based on the random access configuration information (<NUM>) received from the base station and a reference subcarrier spacing, SCS associated with an uplink bandwidth part, BWP configured for the first random access message, wherein the reference SCS is different from an actual SCS received in the random access configuration information;
determining (<NUM>) a second time duration for a payload (<NUM>) of the first random access message based on the random access configuration information received from the base station and the reference SCS; and
transmitting (<NUM>) the first random access message to the base station to initiate a random access procedure.