OFDM Timing Control Circuit Using Partial Cyclic Prefix Correlation
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Solution Overview
Problem
Conventional timing estimation techniques in digital radio communication systems, such as those using orthogonal frequency division multiplexing (OFDM), face significant latency and resource consumption due to complex correlation operations, especially in multi-path channel conditions, leading to inefficient signal acquisition and performance loss.
Innovation Solution
A timing control circuit that utilizes a buffer to store OFDM samples and performs correlations only on a portion of the cyclic prefix and adjacent guard band samples, adjusting the timing until the correlation sums for both portions are substantially equal, thereby reducing computational complexity and improving synchronization in multi-path channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional correlation techniques are used for timing estimation, then timing synchronization can be achieved, but computational complexity and latency increase significantly
Solution Approach 1:
The patent divides the cyclic prefix into multiple portions (first portion and second portion) and processes them separately through different correlation paths. This segmentation allows the system to reduce computational complexity by only processing necessary portions while maintaining timing estimation accuracy through the combined correlation results.
Solution Approach 2:
Instead of performing full correlation operations on the entire cyclic prefix, the patent applies partial correlation by processing only specific portions (first and second portions) of the cyclic prefix. This partial action reduces the number of computations required while still providing sufficient information for accurate timing estimation.
2Measurement precision
If conventional correlation techniques are used for timing estimation, then timing synchronization can be achieved, but signal acquisition time increases due to latency
Solution Approach 1:
By segmenting the cyclic prefix into multiple portions and processing them in parallel through different correlation paths, the system reduces the sequential processing time required for timing estimation. This segmentation enables more efficient use of computational resources and faster signal acquisition.
Solution Approach 2:
The patent maintains continuous timing estimation through overlapping correlation operations on different portions of the cyclic prefix. This continuous action ensures that timing information is constantly updated without idle processing time, reducing overall signal acquisition time while maintaining accuracy.
3Measurement precision
If conventional correlation techniques are used, then timing estimation can be performed, but computing resources are consumed significantly
Solution Approach 1:
The patent segments the cyclic prefix into multiple portions and processes them through selective correlation paths, reducing the total number of computations required. This segmentation strategy maintains timing estimation accuracy while significantly reducing computing resource consumption by only processing necessary portions of the signal.
Solution Approach 2:
The system performs partial correlation operations on specific portions of the cyclic prefix rather than full correlation on the entire signal. This partial action reduces computing resource consumption while providing sufficient accuracy for timing estimation, avoiding unnecessary computational effort.
4Measurement precision
If conventional correlation techniques are used, then timing estimation can be performed, but performance is lost in multi-path channel conditions
Solution Approach 1:
The patent segments the cyclic prefix into multiple portions and processes them through separate correlation paths, allowing the system to better handle multi-path effects. By analyzing different portions independently and combining their results, the system can distinguish between legitimate signal paths and interference, improving reliability in multi-path channel conditions.
Solution Approach 2:
The system uses correlation results from different portions of the cyclic prefix to feedback and adjust timing estimates. This feedback mechanism allows the system to adapt to changing channel conditions and maintain accurate timing estimation even in challenging multi-path environments by continuously refining the timing based on correlation patterns.
Data Source
AI summary
In one aspect, an apparatus includes: a buffer to store orthogonal frequency division multiplexing (OFDM) samples of one or more OFDM symbols; a fast Fourier transform (FFT) engine coupled to the buffer, the FFT engine to receive the one or more OFDM samples from the buffer and convert each of the one or more OFDM samples into a plurality of frequency domain sub-carriers; and a timing control circuit coupled to the buffer. The timing control circuit may control timing based at least in part on a difference between a first correlation sum for a first portion of a cyclic prefix of a first one of the one or more OFDM symbols and a second correlation sum for a second portion of the cyclic prefix.