Zero Correlation Zone Length Determination for Random Access Optimization
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Solution Overview
Problem
Current mobile communication systems face challenges in determining a limited set of Zero Correlation Zone (ZCZ) lengths for Random Access Preamble (RAP) sequences, leading to increased signaling overhead and suboptimal random access performance, especially as cell radii vary.
Innovation Solution
A method to determine a limited set of ZCZ lengths that ensures the product of ZCZ length and symbol period exceeds the sum of round trip time and delay spread, allowing for efficient uplink synchronization while minimizing signaling overload, by constructing a set of cyclic shift increment values that maintain a maximum relative difference in preamble generation across varying cell radii.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a limited set of ZCZ lengths is used, then signaling overhead is reduced, but random access performance deteriorates due to suboptimal coverage across varying cell radii
Solution Approach 1:
The patent applies parameter changes by dynamically selecting ZCZ length and cyclic shift increment values based on cell radius. The base station determines appropriate parameters from predefined sets and signals them to mobile terminals, allowing the system to adapt to different cell sizes while maintaining good random access performance and reducing signaling overhead through limited predefined sets.
Solution Approach 2:
The patent implements dynamics by making the ZCZ length and cyclic shift increment configurable and adaptable rather than fixed. The base station can adjust these parameters based on actual cell radius conditions, enabling the system to optimize random access performance for both small and large cells while using limited predefined sets to control signaling overhead.
2Reliability
If ZCZ length is increased to cover larger cell radii, then uplink synchronization is improved, but the number of available preambles decreases
Solution Approach 1:
The patent resolves this contradiction by introducing cyclic shift increment as an additional parameter that can be independently optimized. By adjusting both ZCZ length and cyclic shift increment based on cell radius, the system can maintain adequate uplink synchronization coverage while preserving more preambles per root sequence compared to only increasing ZCZ length.
Solution Approach 2:
The patent applies segmentation by dividing the preamble space into multiple root sequences, each with its own configurable ZCZ length and cyclic shift increment parameters. This allows the system to distribute the 64 preamble requirements across multiple root sequences (e.g., 8 root sequences with 8 preambles each), maintaining synchronization performance while preserving preamble quantity.
3Productivity
If cyclic shift increment is decreased to increase preamble count, then preamble generation efficiency is improved, but Zero Correlation Zone properties deteriorate
Solution Approach 1:
The patent resolves this contradiction by jointly optimizing both ZCZ length and cyclic shift increment parameters based on cell radius. Rather than fixing one parameter and adjusting the other, the system selects coordinated pairs of parameters from predefined sets, ensuring that ZCZ properties are maintained while maximizing preamble generation efficiency for different cell sizes.
Data Source
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AI summary
A method of determining a set of Zero Correlation Zone (ZCZ) lengths, includes: determining the length of a root sequence, and selecting such a set of ZCZ lengths that, for any cell radius, the maximum number of preambles obtained from a ZCZ length which is selected from the selected set of ZCZ lengths is closest to the maximum number of preambles determined from a ZCZ length which is selected from the set of all integers, wherein the maximum number of preambles is determined from the length of the root sequence and a ZCZ length selected. Also provided are an apparatus, a base station and a mobile communication system of determining a set of ZCZ lengths. This invention provides a technical solution for selecting a better limited set of ZCZ lengths by which signaling overload is reduced.