Base Station RACH Resource Allocation for Unlicensed Band Latency
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Solution Overview
Problem
The high latency in random access procedures for terminals in unlicensed frequency bands, particularly due to the listen before talk mechanism, leads to increased uncertainty and latency in accessing a cell, as the timing mismatch between LBT success and allocated RACH resource availability causes delays in preamble transmission.
Innovation Solution
A resource allocation method where a base station sends a configuration message to a terminal, including time domain position information of the RACH resource, allowing the terminal to determine the optimal time for preamble transmission, thereby reducing latency and improving access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal performs LBT before sending the preamble, then the channel access is controlled to avoid collision, but the access latency increases and timing uncertainty increases
Solution Approach 1:
The base station performs LBT in advance before allocating RACH resources, and the terminal transmits the preamble immediately after receiving the allocation without needing to perform LBT again. This preliminary action by the base station eliminates the timing uncertainty and latency for the terminal.
Solution Approach 2:
The base station acts as an intermediary that performs the LBT function on behalf of the terminal. By doing so, the base station resolves the contradiction by ensuring channel availability before resource allocation, while the terminal can proceed with immediate preamble transmission.
2Reliability
If the terminal waits for LBT success before sending preamble, then channel collision is avoided, but the timing mismatch with allocated RACH resource causes increased latency
Solution Approach 1:
The base station completes the LBT action preliminarily before RACH resource allocation. The time domain position information in the configuration message indicates when the RACH resource becomes available after the base station's LBT success, allowing the terminal to transmit immediately without additional waiting.
3Adaptability or versatility
If dynamic RACH resource allocation is implemented, then access flexibility is improved, but the complexity of resource management increases
Solution Approach 1:
The base station serves as an intermediary that manages the dynamic allocation process. It receives LBT results, determines appropriate RACH resource timing, and communicates this through configuration messages containing time domain position information, simplifying the terminal's role to just receiving and executing the allocation.
Data Source
AI summary
Embodiments of this application disclose a resource allocation method, a base station, and a terminal. The method includes: A base station sends a configuration message to a terminal, where the configuration message is used to configure, for the terminal, a random access channel RACH resource used in a channel occupancy time COT. The base station receives a random access request that is sent by the terminal based on the RACH resource allocated by using the configuration message. According to embodiments of this application, a random access latency of the terminal can be reduced.