End-to-End Delay Measurement for Random Access Preamble Optimization
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Solution Overview
Problem
In distributed communications systems, determining an accurate cyclic shift for generating random access preambles is challenging due to varying signal propagation delays, leading to increased interference among preambles and reduced performance.
Innovation Solution
Measuring end-to-end delays between signal sources and remote units in a distributed communications system, allowing for the accurate determination of equivalent coverage range and minimization of Zadoff-Chu sequences used, thereby reducing interference among random access preambles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the cyclic shift is increased to accommodate signal propagation delays in a distributed communications system, then the coverage range is extended, but the number of available random access preambles decreases due to fewer Zadoff-Chu sequences
Solution Approach 1:
The patent measures the actual end-to-end delay in the distributed communications system and uses this measured delay value to dynamically determine the appropriate cyclic shift length. This parameter change approach allows the system to adapt the cyclic shift to the actual propagation conditions rather than using a fixed conservative estimate, thereby optimizing the balance between coverage range and the number of available preambles.
2Quantity of substance
If more Zadoff-Chu sequences are used to generate random access preambles, then the number of available preambles increases, but the interference among preambles increases
Solution Approach 1:
The system implements a feedback mechanism where the measured end-to-end delay information is used to determine the optimal cyclic shift length. This feedback loop allows the system to adjust the preamble generation parameters based on actual system conditions, ensuring that the cyclic shift is long enough to prevent interference while not being excessively long, which would waste available preambles.
3Object-generated harmful factors
If a fixed conservative cyclic shift is used without measuring actual delays, then interference is minimized, but the coverage range is reduced and system resources are wasted
Solution Approach 1:
The patent performs preliminary delay measurement action before determining the cyclic shift for random access preamble generation. By measuring the actual end-to-end delay in advance, the system can calculate the precise cyclic shift needed for the given propagation conditions, avoiding both the interference caused by insufficient cyclic shift and the resource waste caused by excessive cyclic shift.
Data Source
AI summary
Measuring an end-to-end delay(s) in a distributed communications system (DCS) is disclosed. The DCS is coupled to a signal source(s) supporting multiple logical channels and includes multiple remote units each communicating in one or more of the logical channels. The DCS is configured to measure an end-to-end delay(s), which includes a path delay(s) between the signal source and the remote units and a local delay(s) at each of the remote units, for each of the logical channels. The measured end-to-end delay(s) can help the signal source to more accurately determine an equivalent coverage range of the DCS, thus making it possible to generate random access preambles for the DCS based on as few Zadoff-Chu (ZC) sequences as possible. By generating the random access preambles based on fewer ZC sequences, it is possible to minimize interference among the random access preambles, thus helping to improve random access performance in the DCS.