PRACH Beam Association for Low-Overhead Random Access Coverage
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Solution Overview
Problem
The coverage of the Physical Random Access Channel (PRACH) in wireless communication systems has not been adequately addressed, which is crucial for initial access and beam failure recovery, leading to potential bottlenecks in uplink performance, especially in scenarios with large uplink traffic such as video upload.
Innovation Solution
Implementing multiple PRACH transmissions using different uplink transmission beams or spatial filters to achieve SNR combining gain and beam diversity, with a method to determine the number of transmissions and beam directions through a unified solution applicable to various communication scenarios, including single- and multi-carrier, single- and multi-antenna, and terminal and base station scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PRACH transmissions are performed using different uplink transmission beams or spatial filters, then PRACH coverage performance is improved through SNR combining gain and beam diversity gain, but signaling overhead increases due to the need to indicate beam directions and spatial filters
Solution Approach 1:
The UE determines the spatial filter for Msg3 transmission by itself based on the association between the random access occasion and spatial filter, without requiring explicit network indication. The network only needs to indicate the random access occasion, and the UE autonomously derives the corresponding spatial filter from pre-configured associations, making the system self-organizing and reducing signaling overhead.
Solution Approach 2:
The random access occasion indicator serves multiple functions: it identifies the specific random access occasion for the preamble transmission and simultaneously indicates the spatial filter to be used for subsequent Msg3 transmission. This multi-functionality reduces the need for separate signaling for beam indication.
2Measurement precision
If multiple PRACH transmissions are performed using different uplink transmission beams or spatial filters, then more accurate beam direction guidance is provided for Msg3 transmission, but the complexity of the random access procedure increases
Solution Approach 1:
The association between random access occasions and spatial filters is pre-configured and stored in the UE before the random access procedure begins. When the UE needs to perform random access, it simply retrieves the pre-configured association corresponding to the indicated random access occasion, avoiding complex real-time beam selection and reducing procedural complexity.
3Productivity
If the same preamble is used for repeated sending on multiple ROs, then resource utilization is improved, but existing random access signalings cannot provide beam direction indication
Solution Approach 1:
Instead of using different preambles to identify different beams (one-dimensional approach), the patent introduces a new dimension by associating different random access occasions with different spatial filters. The same preamble can be reused across multiple ROs, and the beam direction is indicated through the RO identifier rather than the preamble identifier, enabling both resource reuse and beam indication.
Data Source
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AI summary
Disclosed in the present application are a method and apparatus used in a node for wireless communication. The method comprises: a first node sending K first-type sequences on K random access occasions by respectively using K spatial-domain filters; receiving first signaling and a first signal in a first time window, wherein the first signaling is used for scheduling the first signal, and at least one of the first signaling and the first signal is used for determining a first identifier; and sending a second signal by using a second spatial-domain filter, wherein the first signal is used for indicating a time-frequency resource occupied by the second signal, the first identifier is used for indicating a first random access occasion, which is one of the K random access occasions, the first random access occasion corresponds to a first spatial-domain filter, which is one of the K spatial-domain filters, and the first spatial-domain filter is used for determining the second spatial-domain filter. The present application saves on resource overheads and signaling overheads.