Zadoff-Chu Sequence Length Adaptation for LTE Interference
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Solution Overview
Problem
In 3GPP LTE systems, ZC sequences of different sequence lengths transmitted between cells result in low cross correlation, leading to mutual interference and degraded receiving performance, and increase the circuit scale and calculation complexity due to varying sequence lengths for different transmission bandwidths.
Innovation Solution
A wireless transmitting apparatus and method that determines a basic sequence length for multiple transmission bandwidths, performing cyclic extension or truncation to maintain low cross correlation and reduce circuit complexity by generating constant amplitude and zero-autocorrelation code sequences of a common basic sequence length for different transmission bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ZC sequences of different sequence lengths are used for different transmission bandwidths, then the sequences can be matched to various bandwidth requirements, but cross correlation between sequences increases causing mutual interference and degraded receiving performance
Solution Approach 1:
The patent applies parameter changes by modifying the sequence length parameter based on transmission bandwidth requirements. Different ZC sequences with different lengths (N=13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53) are selected and applied to different transmission bandwidths, allowing the system to adapt to various bandwidth conditions while maintaining sequence properties that minimize interference
Solution Approach 2:
The patent segments the sequence selection into different groups based on transmission bandwidth ranges. By dividing the bandwidth spectrum into segments and assigning specific sequence lengths to each segment, the system achieves both bandwidth adaptability and controlled cross-correlation within each segment
2Adaptability or versatility
If ZC sequences of different sequence lengths are used for different transmission bandwidths, then bandwidth matching is achieved, but circuit scale and calculation complexity increase
Solution Approach 1:
The patent uses parameter changes to systematically vary sequence length based on bandwidth requirements. By establishing a clear mapping between transmission bandwidth and sequence length parameters, the system achieves bandwidth matching while keeping the complexity management systematic and predictable
Solution Approach 2:
The patent implements a universal sequence generation framework where a single ZC sequence generation mechanism can produce sequences of multiple lengths. This multi-functional approach allows the same hardware/software structure to handle different bandwidths by simply changing the sequence length parameter, reducing overall circuit complexity
Data Source
AI summary
A radio transmission device and a radio communication method employ sequence length decision units which hold a correspondence in which one basic sequence length is set for a plurality of transmission bandwidths. The sequence length decision units acquire transmission bandwidth information and decide a sequence length corresponding to the acquired transmission bandwidth information. A decision is made as to which of the cyclic extension process or the truncation process is to be executed on a Zadoff-Chu sequence according to the sizes of the acquired transmission bandwidth information and the basic sequence length. Then, a difference between the transmission bandwidth and the basic sequence length, i.e., the number of possible cyclic extension/truncation symbols, is obtained.