5G NR Two-Step Random Access Contention Resolution

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Solution Overview

Problem

The two-step random access procedure in 5G New Radio (NR) systems faces challenges in managing contention conflicts, which affect the efficiency and delay of random access processes.

Innovation Solution

A wireless communication method where a terminal device sends a first message with a preamble ID and an uplink message containing a first identity, and then monitors a PDCCH scrambled by a target RNTI to determine if a contention conflict is resolved based on a second message scheduled by the PDCCH and the uplink message.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a two-step random access procedure is implemented to reduce random access delay, then the random access delay is reduced, but contention conflict management becomes more difficult

Engineering Contradiction:

Improverandom access delayVSAvoidcontention conflict management

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The terminal device includes its identity information in the first message (MSG A) upfront, before the contention resolution phase. This preliminary inclusion of identity allows the network device to identify multiple contending terminals earlier, enabling more effective contention resolution in the two-step procedure while maintaining reduced access delay.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If identity information is included in the first message of two-step random access, then contention conflict resolution is improved, but message complexity increases

Engineering Contradiction:

Improvecontention conflict resolutionVSAvoidmessage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the random access preamble and uplink data transmission into a single first message (MSG A). By merging these functions, the identity information is efficiently included without requiring separate signaling messages, thus improving contention resolution while avoiding excessive message complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If the terminal device monitors PDCCH scrambled by target RNTI to determine contention resolution, then contention conflict detection accuracy is improved, but processing complexity increases

Engineering Contradiction:

Improvecontention conflict detection accuracyVSAvoidmonitoring and processing

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces a target RNTI as an intermediary identifier that the terminal device uses to monitor PDCCH for contention resolution. This RNTI is derived from the terminal's identity and serves as a efficient key for the network to address the terminal, improving detection accuracy while keeping processing manageable through standardized RNTI operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250063572A1Wireless communication method, terminal device, and network device

Publication Date: 2025.02.20 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD

AI summary

A wireless communication method, a terminal device, and a network device are disclosed. The method includes: a terminal device sends a first message to a network device, the first message including a preamble for a random access and an uplink message; the terminal device monitors a PDCCH scrambled by a target RNTI; and according to a second message scheduled by the PDCCH and the uplink message, determines whether the contention collision is solved.