Two-Step RACH Signaling With Beam Feedback for Low-Latency Access
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Solution Overview
Problem
Existing wireless communication systems, particularly in LTE and NR, face challenges in reducing latency and optimizing random access channel procedures, especially in scenarios requiring low latency like 5G/NR systems, where the traditional four-step RACH procedure may not meet the requirements.
Innovation Solution
Implementing a two-step random access channel (RACH) procedure that combines Msg1 and Msg3 communications into a single MsgA transmission, along with a RACH report from the UE providing parameters like MsgA payload quantity, signal strength, and success/failure indicators, allowing the BS to generate an optimized RACH configuration for reduced latency and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a traditional four-step RACH procedure is used, then the protocol compatibility with existing LTE/NR systems is maintained, but the access latency is high and does not meet low-latency requirements
Solution Approach 1:
The patent combines Msg1 (random access preamble) and Msg3 (upper layer payload) into a single transmission called MsgA in the two-step RACH procedure. This merging eliminates the need for separate Msg2 and Msg4 transmissions, directly reducing access latency while maintaining protocol functionality
Solution Approach 2:
The patent segments the RACH procedure into two distinct steps: first step transmits MsgA containing both preamble and payload, and second step transmits MsgB containing random access response and upper layer response. This segmentation simplifies the overall procedure from four steps while reducing latency
2Reliability
If beamforming is used to improve signal strength, then the signal quality for specific beams is enhanced, but the complexity of beam management and selection increases
Solution Approach 1:
The patent implements feedback mechanisms where the UE reports beam failure detection information and the BS provides beam failure recovery indications. This feedback loop enables dynamic beam selection and optimization, improving signal quality while managing complexity through automated decision-making
Solution Approach 2:
The patent introduces dynamic beam failure recovery procedures where the system can switch between different beams based on real-time conditions. The beam selection is no longer static but adapts dynamically to channel conditions, improving reliability while containing complexity through predefined recovery procedures
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may generate a report for one or more two-step random access channel (RACH) procedures between the UE and a base station (BS), wherein the RACH report includes at least one of an indication of a quantity of message A (MsgA) payloads transmitted during the one or more two-step RACH procedures on each beam of one or more beams associated with the BS, an indication of one or more parameters associated with each MsgA communication transmitted during the one or more two-step RACH procedures, or an indication of whether a respective signal strength for each beam, associated with the one or more two-step RACH procedures, satisfies a signal strength threshold. The UE may transmit the report to the BS. Numerous other aspects are provided.