Timing Control for Random Access Channel in 5G Wireless Systems

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Solution Overview

Problem

In 5G/NR wireless systems, the two-step Random Access Channel (RACH) procedure faces challenges in synchronizing uplink connections due to the lack of timing advance (TA) information for the msg3 communication, leading to potential interference and delays in synchronizing the connection between user equipment (UE) and base stations (BS).

Innovation Solution

The UE determines an estimated timing advance (TA) for the msg3 communication, allowing it to transmit accurately, while the BS can decode the msg3 communication using a BS-estimated TA, ensuring the message arrives within the expected FFT engine window, thus reducing interference and delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the two-step RACH procedure is used to reduce latency, then connection establishment speed is improved, but uplink synchronization accuracy deteriorates due to lack of TA information for msg3

Engineering Contradiction:

Improveconnection establishment latencyVSAvoiduplink timing synchronization accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The base station performs preliminary estimation of the timing advance for msg3 before the UE transmits msg3. The BS calculates the expected arrival time of msg3 based on the received msg1 timing and downlink propagation delay, preparing the FFT engine window in advance to accurately receive and decode msg3 without requiring TA information in msg2.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If TA information is not provided in msg2 communication, then the two-step RACH procedure structure is simplified, but interference in uplink transmission increases due to timing misalignment

Engineering Contradiction:

ImproveRACH procedure signaling complexityVSAvoiduplink interference

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The base station uses feedback from the msg1 reception timing and downlink propagation delay measurements to determine the optimal FFT engine window for receiving msg3. This feedback mechanism allows the BS to compensate for timing advances without explicit TA signaling, maintaining synchronization while keeping the procedure simple.

Inventive Principle:

Principle #23Feedback

3Ease of operation

If the UE transmits msg3 without estimated TA, then transmission simplicity is improved, but decoding accuracy at BS deteriorates due to timing uncertainty

Engineering Contradiction:

ImproveUE transmission simplicityVSAvoidmsg3 decoding accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The base station serves itself by autonomously estimating the msg3 arrival time using its own measurements of msg1 reception timing and downlink propagation delay. This self-service approach eliminates the need for the UE to calculate and apply TA for msg3, maintaining UE transmission simplicity while ensuring accurate BS decoding through the BS's own timing estimation capabilities.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11483869B2Timing control for random access channel (RACH)

Publication Date: 2022.10.25 QUALCOMM INC

AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine an estimated timing advance (TA) for one or more communications included in a set of communications of a random access channel procedure. The UE may transmit, to a base station, the one or more communications based at least in part on the estimated TA. Numerous other aspects are provided.