Two-Step RACH Messaging to Reduce Initial Access Latency
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Solution Overview
Problem
Existing wireless communication systems face latency issues in the random access procedure, particularly in 4G and 5G networks, which hinder faster and more efficient communication processes.
Innovation Solution
A two-step random access channel (RACH) procedure is introduced, combining the functions of Msg 1 and Msg 3 into a single message (Msg A) and Msg 2 and Msg 4 into another message (Msg B), with an indication in Msg B specifying the type of response to enhance synchronization and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a four-step random access procedure is used, then the access process is thorough and reliable, but the overall initial access latency is high
Solution Approach 1:
The patent combines the four-step random access procedure into a two-step procedure by merging Msg1 and Msg3 into a single uplink message, and merging Msg2 and Msg4 into a single downlink message. This consolidation reduces the number of interaction rounds between UE and BS, thereby reducing initial access latency while maintaining access reliability through integrated acknowledgment and contention resolution mechanisms.
Solution Approach 2:
The patent incorporates preliminary actions by including the acknowledgment and contention resolution identity in the same downlink message (Msg B) that responds to the uplink message. This preliminary inclusion of multiple functions in a single message exchange eliminates the need for separate subsequent messages, reducing the overall access time while ensuring reliable connection establishment.
2Loss of information
If multiple messages are exchanged in the random access procedure, then information can be thoroughly transmitted, but the communication efficiency is reduced
Solution Approach 1:
The patent merges multiple information elements (acknowledgment, contention resolution identity, and uplink grant) into a single downlink message (Msg B). This consolidation ensures that all necessary information is transmitted completely while reducing the number of message exchanges, thereby improving communication efficiency without sacrificing information completeness.
Solution Approach 2:
The downlink message (Msg B) in the patent serves multiple functions simultaneously: it provides acknowledgment of the received uplink message, includes contention resolution identity for collision handling, and carries uplink grant for subsequent transmission. This multi-functionality ensures complete information transmission while enhancing communication efficiency by eliminating the need for separate dedicated messages for each function.
Data Source
AI summary
Methods, apparatus and systems for indicating information in a random access procedure. In one embodiment, a method performed by a wireless communication device is disclosed. The method includes: transmitting, to a wireless communication node, a first message including a preamble and a payload for an access to the wireless communication node; and receiving, from the wireless communication node, a second message including a response to the first message, the second message including an indication indicating a type of the response selected from a plurality of types.