Multi-User MIMO Reception with Timing-Offset Signal Separation
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Solution Overview
Problem
In multi-user MIMO systems using single-carrier or multicarrier transmissions, signal separation is challenging when signals from multiple transmitting stations arrive at different reception timings that exceed the guard interval length, leading to performance deterioration due to loss of orthogonality between frequency components.
Innovation Solution
A reception device employing orthogonal conversion, detection, inverse orthogonal conversion, and rectangular filtering to extract time series data while minimizing the impact of timing offsets, along with multi-user detection weights and successive interference cancellation to separate signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guard interval length is increased to accommodate timing offsets between transmitting stations, then signal orthogonality is maintained, but transmission efficiency and throughput deteriorate
Solution Approach 1:
The patent changes the parameter of guard interval length dynamically based on the actual timing offset conditions. Instead of using a fixed long guard interval, the system adjusts the guard interval length to match the actual timing differences, thereby maintaining orthogonality while minimizing the overhead and maximizing transmission efficiency.
2Productivity
If the guard interval length is decreased to improve transmission efficiency, then throughput increases, but signal orthogonality is destroyed and performance deteriorates
Solution Approach 1:
The system dynamically adjusts the guard interval parameter based on measured timing offsets. When timing offsets are small, a shorter guard interval is used to maintain high efficiency. When timing offsets are large, the guard interval is extended to preserve orthogonality, thus optimizing the trade-off between efficiency and reliability.
3Measurement precision
If complex signal processing methods are used to separate signals with timing offsets, then signal separation performance improves, but device complexity increases
Solution Approach 1:
The patent applies preliminary timing alignment and guard interval insertion before the main signal processing stages. By pre-processing the signals to account for timing offsets through guard intervals, the subsequent signal separation requires simpler processing, thus achieving good separation performance without excessive hardware complexity.
4Measurement precision
If longer processing time is allocated for signal separation, then separation accuracy improves, but transmission delay increases
Solution Approach 1:
The guard interval is inserted in advance to capture the timing offset effects before the main processing occurs. This preliminary action allows the receiver to quickly align and separate signals without requiring extensive processing time, thereby maintaining high separation accuracy while minimizing transmission delay.
Data Source
AI summary
Orthogonal converters perform orthogonal conversion on the N time-series data extracted from a received radio signal. Multi-user detectors extract transmitted signals from respective transmission devices, from the time-series data which has been subjected to the orthogonal conversion. Inverse orthogonal converters perform inverse orthogonal conversion on the extracted transmitted signal. Rectangular filter circuits remove Mh time-series data at the front end and Mt time-series data at the rear end, from the transmitted signal which has been subjected to the inverse orthogonal conversion, so as to extract Nw time-series data. Deinterleaver circuits deinterleave the aforementioned time-series data. Decoders decode the time-series data for output.