# US 12,772,283 B2 · Techniques for random access channel (RACH) enhancements for new radio unlicensed (NR-U) communications

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- Number: US 12,772,283 B2
- Document ID: US12772283B2
- Status: Granted
- Kind: B2
- Application number: 17/061,125
- Filed: 2020-10-01
- Published: 2021-05-06
- Granted: 2026-10-20
- Earliest claimed: 2019-10-03
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Pravjyot Singh Deogun; Abhijit Bhattacharya; Xiaoxia Zhang; Ozcan Ozturk; Jing Sun; Kapil Bhattad; Tanumay Datta
- Web page: https://patentgrep.com/patent/US12772283B2

## CPC

- H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA]
- H04W 24/08: Testing, {supervising or monitoring} using real traffic
- H04W 52/36: with a discrete range or set of values, e.g. step size, ramping or offsets
- H04W 72/0446: Resources in time domain, e.g. slots or frames
- H04W 74/02: Hybrid access
- H04W 74/0833: Random access procedures, e.g. with 4-step access
- H04W 76/18: Management of setup rejection or failure
- H04W 76/19: Connection re-establishment
- H04W 74/0836: with 2-step access
- H04W 74/0838: using contention-free random access [CFRA]
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

The present disclosure relates to wireless communications, and more particularly to enhancements to a random access channel (RACH) procedure for use in New Radio (e.g., 5G) communications in the unlicensed spectrum (also referred to as NR-U). The present disclosure provides a user equipment (UE) or network entity that determines an available RACH occasion (RO) within a slot for a message transmission according to one of a two-step RACH procedure or a four-step RACH procedure, wherein the available RO is adjacent to at least one unavailable RO within the slot. The UE or network entity may further perform, during the RO, the message transmission according to one of the two-step RACH procedure or the four-step RACH procedure.

## Claims

### Claim 1

A method of wireless communications at a user equipment (UE), comprising:
performing a first listen-before-talk (LBT) procedure for a physical random access channel (PRACH) transmission of a Message A transmission in a two-step random access channel (RACH) procedure and a second LBT procedure for a physical uplink shared channel (PUSCH) transmission of the Message A transmission in the two-step RACH procedure;
incrementing a power ramping counter associated with a common power ramping for both the PRACH and the PUSCH transmissions;
identifying a success of the first LBT procedure for the PRACH transmission;
transmitting the PRACH transmission over a PRACH resource based on identifying success of the first LBT procedure;
identifying a failure of the second LBT procedure for the PUSCH transmission;
performing a PUSCH transmission attempt at a subsequent PUSCH resource of multiple PUSCH transmission opportunities singularly associated to the PRACH resource, based on identifying the failure of the second LBT procedure for the PUSCH transmission;
identifying a failure of all LBT procedures for the PUSCH transmission;
receiving one or both of a fallback random access response (RAR) or a second message of two-step RACH procedure in response to identifying the failure of all LBT procedures for the PUSCH transmission;
identifying whether a power ramping parameter for the PRACH transmission is different from a power ramping parameter for the PUSCH transmission;
forgoing power ramping for the PUSCH transmission associated with identifying that the power ramping parameter for the PRACH transmission is different from the power ramping parameter for the PUSCH transmission; and
performing the power ramping for the PUSCH transmission associated with identifying that the power ramping parameter for the PRACH transmission is not different from the power ramping parameter for the PUSCH transmission.

### Claim 2 (depends on 1)

The method of claim 1, further comprising forgoing monitoring for a network response until the PUSCH transmission is successful.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
monitoring for the fallback RAR during a monitoring duration associated with identifying the failure of all LBT procedures for the PUSCH transmission.

### Claim 4 (depends on 3)

The method of claim 3, further comprising incrementing a message transmission counter based on determining that a fallback message is not received within the monitoring duration.

### Claim 5

An apparatus for wireless communication, comprising:
a transceiver;
a memory configured to store instructions; and
at least one processor communicatively coupled with the transceiver and the memory, wherein the at least one processor is configured to:
perform a first listen-before-talk (LBT) procedure for a physical random access channel (PRACH) transmission of a Message A transmission in a two-step random access channel (RACH) procedure and a second LBT procedure for a physical uplink shared channel (PUSCH) transmission of the Message A transmission in the two-step RACH procedure;
increment a power ramping counter associated with a common power ramping for both the PRACH and the PUSCH transmissions;
identify a success of the first LBT procedure for the PRACH transmission;
transmit the PRACH transmission over a PRACH resource based on identifying success of the first LBT procedure;
identify a failure of the second LBT procedure for the PUSCH transmission;
perform a PUSCH transmission attempt at a subsequent PUSCH resource of multiple PUSCH transmission opportunities singularly associated to the PRACH resource, based on identifying the failure of the second LBT procedure for the PUSCH transmission;
identify a failure of all LBT procedures for the PUSCH transmission;
receive one or both of a fallback random access response (RAR) or a second message of two-step RACH procedure associated with identifying the failure of all LBT procedures for the PUSCH transmission;
identify whether a power ramping parameter for the PRACH transmission is different from a power ramping parameter for the PUSCH transmission;
forgo power ramping for the PUSCH transmission associated with identifying that the power ramping parameter for the PRACH transmission is different from the power ramping parameter for the PUSCH transmission; and
perform the power ramping for the PUSCH transmission associated with identifying that the power ramping parameter for the PRACH transmission is not different from the power ramping parameter for the PUSCH transmission.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the at least one processor is further configured to forgo monitoring for a network response until the PUSCH transmission is successful.

### Claim 7 (depends on 5)

The apparatus of claim 5, wherein the at least one processor is further configured to:
monitor for the fallback RAR during a monitoring duration associated with identifying the failure of all LBT procedures for the PUSCH transmission.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the at least one processor is further configured to increment a message transmission counter associated with identifying that a fallback message is not received within the monitoring duration.