Symbol Sampling in High Delay Spread Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional symbol synchronization methods in radio communications take a long time to converge to optimal synchronization in high delay spread environments, leading to increased time required for initial synchronization and call start due to the limited number of synchronization symbols.
Innovation Solution
A method involving oversampling of a time-varying baseband waveform at a rate m times the symbol rate, calculating error values for each data sample position, and determining the optimal sample time based on these error values to accelerate synchronization, using all received symbol data for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional synchronization methods using limited synchronization symbols are used, then bandwidth for user data throughput is maximized, but the time required to establish initial synchronization and call start increases significantly in high delay spread environments
Solution Approach 1:
The patent applies partial action by using only a limited number of oversampled symbols (e.g., 3-7 symbols) from each synchronization field for rapid synchronization, rather than processing all available symbols. This provides enough information to achieve fast convergence without requiring excessive processing time, thus resolving the contradiction between fast synchronization and bandwidth efficiency.
2Reliability
If the number of synchronization symbols is increased to improve synchronization accuracy, then bit-error-rate performance improves, but the overhead increases and bandwidth for user data decreases
Solution Approach 1:
The patent changes the parameter of sampling rate by oversampling the limited synchronization symbols at multiple rates (e.g., 0.5, 1.0, 1.5 times the symbol rate) and selecting the optimal rate based on error metrics. This transforms a limited set of symbols into multiple candidate samples, achieving improved BER performance without increasing the number of synchronization symbols or overhead.
3Quantity of substance
If conventional symbol synchronization with limited synchronization fields is used, then overhead is minimized, but convergence to optimal synchronization time is slow in high delay spread environments
Solution Approach 1:
The patent adds a temporal dimension by oversampling symbols at multiple time instances (different sample rates and offsets) within each synchronization field. This creates multiple temporal views of the same symbol, enabling faster convergence to optimal synchronization time without requiring more synchronization fields or increasing overhead.
Data Source
AI summary
Symbol sampling in a high time delay spread interference environment includes acquiring (602) a time varying baseband waveform. The waveform has a signal amplitude that varies between one of a plurality of symbol states. The waveform is sampled (603) at a rate of m times the symbol rate. During an evaluation time, an error value is calculated (604, 606) for each of m data sample positions. Each of the error values comprises an average distance between the measured value of the waveform as indicated by the data sample and a closest known symbol value. The error values are used to create an error surface. Thereafter, the error surface is modeled as a quadratic and an optimal sample time is determined (608, 610, 612) based on finding the time location where the quadratic surface is minimum. A sinc interpolator is then used to resample the data.