Random Access Preamble Repetition Handling in Wireless Systems
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Solution Overview
Problem
In wireless communication systems, particularly in LTE and LTE-Advanced, there is a challenge in determining the Random Access Radio Network Temporary Identifier (RA-RNTI) and transmitting random access responses when repetitions of the random access preamble are incorporated in the random access procedure, especially in enhanced coverage scenarios where MTC devices face significant penetration losses.
Innovation Solution
The method involves transmitting a plurality of repetitions of a random access preamble in a repetition window and monitoring the physical downlink control channel (PDCCH) for random access responses identified by a RA-RNTI, where the RA-RNTI is determined based on a specific subframe within the repetition window, allowing for improved coverage and synchronization in enhanced coverage modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repetitions of random access preamble are transmitted in enhanced coverage mode, then coverage is improved, but the complexity of determining RA-RNTI and transmitting random access responses increases
Solution Approach 1:
The patent segments the random access response transmission into multiple parts corresponding to different repetitions of the random access preamble. Each random access response is associated with a specific repetition instance, allowing the system to handle enhanced coverage scenarios by processing responses for individual repetitions rather than treating them as a single unit. This segmentation reduces the complexity of RA-RNTI determination and response transmission by breaking down the problem into manageable segments.
2Reliability
If multiple repetitions of random access preamble are transmitted, then uplink synchronization is improved, but the time required for random access procedure increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the association between random access responses and specific repetition instances before the actual random access procedure occurs. The network side prepares the response transmission plan in advance, mapping each potential random access response to its corresponding repetition timing. This preliminary configuration enables faster processing during the actual random access procedure, reducing the time delay that would otherwise be incurred by real-time decision-making for each repetition.
Data Source
AI summary
A method of handling random access for a user equipment of a wireless communication system includes transmitting a plurality of repetitions of a random access preamble in a repetition window; and monitoring a physical downlink control channel for at least one random access response identified by a random access radio network temporary identifier (RA-RNTI); wherein the RA-RNTI is determined based on a specific subframe within the repetition window.