Sphere Detector Resource Allocation for MIMO Symbol Detection
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Solution Overview
Problem
In wireless communication systems using multiple transmitting and receiving antennas, the evaluation of all possible symbol combinations becomes infeasible due to high order modulation and a large number of antennas, especially at low signal-to-noise ratios, leading to inefficient data transfer and detection.
Innovation Solution
A system that includes a media access controller and a physical block with multiple receiving antennas, an SNR estimation circuit, and a sphere detector to allocate spectral resources based on signal-to-noise ratio and calculate costs for possible symbol combinations, selecting the most likely combination for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all possible symbol combinations are evaluated for maximum-likelihood detection, then detection accuracy is improved, but computational complexity becomes infeasible for higher order modulation and large number of antennas
Solution Approach 1:
The patent segments the evaluation of symbol combinations by organizing them into cosets and selecting representative symbols for each coset. Instead of evaluating all possible combinations, the system divides the constellation into manageable groups (cosets) and evaluates only representative symbols from each group, significantly reducing computational complexity while maintaining detection accuracy through the sphere detector algorithm.
Solution Approach 2:
The patent applies partial action by evaluating a subset of symbol combinations rather than all possible combinations. The sphere detector algorithm evaluates symbol combinations within a spherical region around the received signal, focusing computational effort on the most likely candidates and ignoring unlikely combinations, thus achieving good detection performance with reduced complexity.
2Productivity
If multiple symbols are transmitted in parallel from multiple antennas, then data transfer rate is improved, but the number of possible symbol combinations increases exponentially
Solution Approach 1:
The patent segments the exponential space of symbol combinations by organizing them into cosets based on the channel matrix structure. This segmentation allows the system to handle multiple antenna transmissions by dividing the combinatorial space into manageable groups, where only representative symbols from each coset need to be evaluated, making parallel transmission from multiple antennas computationally feasible.
Solution Approach 2:
The patent changes the parameter of evaluation from exhaustive combination checking to selective representative symbol evaluation. By transforming the problem from evaluating all combinations to evaluating only representative symbols determined through coset decomposition and sphere detection, the system can maintain high data transfer rates through parallel transmission while controlling computational complexity.
3Ease of operation
If spectral resources are allocated uniformly to all communications, then resource allocation is simple, but communication quality varies with different SNR conditions
Solution Approach 1:
The patent applies local quality by allocating spectral resources differently based on the specific SNR conditions of each communication channel. Instead of uniform allocation, the system determines the appropriate constellation size and sphere radius for each channel based on its SNR, providing locally optimized resource allocation that matches the specific conditions of each communication link and thereby improves overall communication quality.
Data Source
AI summary
A system detects a communication transmitted from multiple transmitting antennas. The system includes a media access controller and a physical block. Based on a signal to noise ratio (SNR), the allocation circuit of the media access controller assigns a portion of a spectral resource to the communication. The physical block includes multiple receiving antennas for receiving the communication, an estimating circuit for determining the SNR of the communication received at the receiving antennas, and a sphere detector. The sphere detector calculates a respective cost for possible combinations of symbols for the transmitting antennas. The sphere detector calculates the respective costs of the possible combinations from the portion of the spectral resource of the communication received at the receiving antennas. The sphere detector selects one of the possible combinations in response to the respective costs. The system detects the transmitted communication to be the symbols of the selected combination.