Multi-stage Group Symbol Detection for LTE Inter-symbol Interference
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Solution Overview
Problem
In Long Term Evolution (LTE) uplink communications, inter-symbol interference (ISI) poses challenges due to the use of single-carrier frequency-division multiple access (SC-FDMA), particularly in dispersive channels, where existing frequency-domain linear equalization methods like LMMSE are limited in performance, especially with large bandwidth and high channel dispersion.
Innovation Solution
A multi-stage group symbol detection method is employed, where the received signal is divided into sub-blocks with increasing size across stages, using frequency-domain combining weights to jointly detect symbols, treating outside symbols as noise, and retaining likely candidates for each stage to improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If frequency-domain linear equalization (LMMSE) is used to handle inter-symbol interference in SC-FDMA uplink, then power amplifier efficiency is improved, but detection performance deteriorates in highly dispersive channels with large bandwidth
Solution Approach 1:
The patent segments the received signal into multiple sub-blocks in the frequency domain, where each sub-block corresponds to a group of subcarriers. By processing sub-blocks separately and combining results, the method achieves better detection performance in dispersive channels while maintaining the computational efficiency and power amplifier benefits of frequency-domain processing.
Solution Approach 2:
The patent transitions from traditional time-domain equalization to frequency-domain sub-block processing, adding a dimensional perspective by organizing subcarriers into sub-blocks. This frequency-domain segmentation allows the receiver to handle inter-symbol interference more effectively while preserving SC-FDMA's power efficiency advantages.
2Measurement precision
If more sophisticated receiver processing is used to improve detection performance in highly dispersive channels, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
By dividing the frequency-domain signal into multiple sub-blocks and processing them separately, the patent reduces the complexity of each individual processing stage while achieving improved overall detection accuracy through the combination of sub-block results.
Solution Approach 2:
The patent applies partial joint detection by processing sub-blocks separately rather than performing full joint detection on all subcarriers simultaneously. This partial action provides a compromise between the simplicity of independent subcarrier detection and the complexity of full joint detection, achieving improved performance without proportional complexity increase.
Data Source
AI summary
A receiver comprises plural receive antennas and electronic circuitry. The plural receive antennas are configured to receive, on plural subcarriers transmitted over a radio interface, a frequency domain signal that comprises contribution from a block of time domain symbols. The electronic circuitry is configured or operable to perform symbol detection of time domain symbols comprising the block by performing a multi-stage joint detection procedure comprising plural stages, and thus serves as a detector (40). For a first stage the block is divided into a first number of sub-blocks each having a sub-block first size. For a second stage the block is divided into a second number of sub-blocks each having a sub-block second size, the sub-block second size being greater than the sub-block first size. For each stage a detector (40) formulates frequency domain combining weights and uses the frequency domain combining weights for combining multiple receive versions of each subcarrier to provide candidate symbol combination values for symbols in each sub-block of the respective stage. For the second stage the detector (40) is further configured to use the candidate symbol combination values of the first stage to formulate joint hypotheses to serve as candidates for the joint detection operation of the second stage.