PRACH Repetition and Dynamic RAR Window for Wireless Coverage
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Solution Overview
Problem
The challenge of enhancing PRACH coverage in wireless communication systems, particularly in scenarios like initial access and beam failure recovery, has not been adequately addressed in existing technologies, leading to issues with receiving random access responses (RAR) when PRACH repetition is employed.
Innovation Solution
A method involving PRACH repetition with enhanced RAR reception mechanisms, including determining K1 time-frequency resources, monitoring a first signaling window, and sending preambles across these resources to improve coverage and reduce unnecessary transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PRACH repetition is employed to enhance coverage, then coverage is improved, but existing RAR receiving mechanisms cannot meet requirements
Solution Approach 1:
The patent implements dynamic RAR reception mechanisms where the UE can flexibly switch between different reception modes (single RAR, multiple RARs, or RAR with repetition) based on the detected PRACH repetition configuration. The time window for RAR reception is dynamically adjusted to accommodate repeated preamble transmissions, allowing the system to adapt coverage enhancement requirements without compromising existing single-preamble operation.
Solution Approach 2:
The patent modifies key parameters of the RAR reception process including the ra-ResponseWindow timing, RAR message structure, and association between preambles and RARs. By changing these parameters to support repeated preamble transmissions and corresponding multiple RAR receptions, the system achieves enhanced coverage while maintaining backward compatibility with existing mechanisms through configurable parameter sets.
2Reliability
If multiple preambles are sent in PRACH repetition, then coverage is enhanced, but initial access delay increases
Solution Approach 1:
The patent applies preliminary action by having the UE send repeated preambles in advance across multiple opportunities before the RAR window closes. The network side prepares to receive and process these repeated preambles with corresponding RAR messages, ensuring that coverage enhancement is achieved without waiting for retransmission cycles. This preliminary repeated transmission approach reduces the overall initial access delay compared to traditional single-attempt mechanisms.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that PRACH repetition and RAR reception occur in a continuous, coordinated manner without idle gaps. The time window configuration ensures that RAR reception is continuously monitored throughout the enhanced coverage period, and preamble transmissions are continuously attempted across available resources, maximizing the probability of successful access while minimizing total access time.
3Reliability
If RAR reception is enhanced to support PRACH repetition, then coverage is improved, but downlink signaling overhead increases
Solution Approach 1:
The patent merges multiple RAR messages into a coordinated reception framework where repeated preambles are associated with corresponding RARs within an extended time window. By combining the handling of multiple preambles and their corresponding RARs into a unified reception process, the system achieves enhanced coverage without proportionally increasing signaling overhead. The merged approach allows efficient processing of repeated access attempts through shared resource allocation and coordinated timing.
Solution Approach 2:
The patent implements universal RAR reception mechanisms that can handle both single-preamble and repeated-preamble scenarios using the same enhanced framework. The multi-functional RAR reception capability allows the system to adapt to different coverage requirements without requiring separate dedicated mechanisms, thereby avoiding excessive signaling overhead. The universal approach efficiently manages resources whether one or multiple preambles are transmitted, optimizing the balance between coverage enhancement and signaling efficiency.
Data Source
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AI summary
Disclosed in the present application are a method and apparatus in a communication node used in wireless communication. The method comprises: a communication node determining K1, wherein K1 is a positive integer greater than 1; starting a first time window at a first moment; monitoring first signaling in the first time window, wherein the first signaling is used for scheduling a random access response; and sending a first preamble in at least a first time-frequency resource among K1 time-frequency resources, wherein any two time-frequency resources among the K1 time-frequency resources do not overlap in a time domain, the first time-frequency resource is the earliest time-frequency resource among the K1 time-frequency resources, the first moment is related to a cut-off moment of at least the first time-frequency resource, the first moment is not earlier than the cut-off moment of the first time-frequency resource and is earlier than a cut-off moment of a second time-frequency resource, the second time-frequency resource is the latest time-frequency resource among the K1 time-frequency resources, and an expiration moment of the first time window is later than the cut-off moment of the second time-frequency resource.