2-Step Random Access MsgA MsgB Latency Reduction

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Solution Overview

Problem

Current wireless communication systems face inefficiencies in random access procedures, particularly in reducing latency and signaling overhead, as they typically involve four-step processes that can be cumbersome and time-consuming.

Innovation Solution

Implementing a 2-step random access procedure, which includes MsgA and MsgB designs, along with mechanisms for fallback to 4-step RA and retransmission, to streamline the process and reduce latency and signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a 4-step random access procedure is used, then reliability is maintained through multiple confirmation steps, but latency increases and signaling overhead grows

Engineering Contradiction:

Improverandom access reliabilityVSAvoidrandom access latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent combines multiple random access steps into a single MsgA transmission that includes both preamble and payload, eliminating the need for separate Msg1 and Msg3 transmissions. This merging reduces the number of round-trip exchanges from four to two, directly reducing latency while maintaining reliability through the integrated confirmation in MsgB

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the random access procedure into two distinct phases: MsgA (preamble + payload) and MsgB (confirmation + uplink grant). This segmentation allows the essential functions of random access to be completed in fewer steps, reducing latency while preserving reliability through the structured confirmation mechanism in MsgB

Inventive Principle:

Principle #1Segmentation

2Loss of information

If a 4-step random access procedure is used, then signaling completeness is ensured, but signaling overhead increases

Engineering Contradiction:

Improvesignaling completenessVSAvoidsignaling overhead

Core Design Contradiction:

Loss of informationVSQuantity of substance

Solution Approach 1:

The patent merges multiple signaling elements into single messages: MsgA combines preamble and payload that would traditionally be separate, and MsgB combines confirmation and uplink grant information. This consolidation reduces the total number of signaling transmissions while maintaining all necessary information exchange

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

MsgB serves multiple functions simultaneously: it confirms successful reception of MsgA, provides uplink grant for subsequent transmission, and enables the UE to proceed with data transmission. This multi-functionality reduces the need for separate signaling messages, decreasing overhead while maintaining signaling completeness

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11540323B22-step random access

Publication Date: 2022.12.27 APPLE INC

AI summary

Apparatuses, systems, and methods for a wireless device to perform 2-step random access procedures. The disclosure identifies features of 2-step random access procedures including configuration (e.g., under what circumstances to use 2-step vs. 4-step random access), message design, fallback procedures, power ramping, backoff, and retransmission procedures.