CMFB Matrix Equalizer for Distortion in Dispersive Channels
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Solution Overview
Problem
Cosine Modulated Filter Bank (CMFB) modulation is sensitive to signal distortions introduced by the transmission channel, leading to performance issues in digital data transmission, especially in channels with significant frequency selectivity, and existing equalization methods are computationally complex and inefficient.
Innovation Solution
A method and device using a matrix equalizer to reduce signal distortion by determining the discrete-time matrix channel impulse response and calculating matrix coefficients based on a linear system of equations, which are then used for equalization, allowing for efficient polyphase implementations and reduced computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CMFB modulation is used for digital data transmission, then spectral containment and flexibility in spectrum usage are improved, but sensitivity to signal distortions increases
Solution Approach 1:
The patent introduces a matrix equalizer as an intermediary component between the CMFB modulator and demodulator. This equalizer, characterized by matrix coefficients W(i) determined from the discrete-time matrix channel impulse response C(i), actively compensates for channel-induced signal distortions. The matrix equalizer processes the received signal to mitigate intersymbol interference and interchannel interference, thereby improving reliability while preserving the spectral containment and flexibility benefits of CMFB modulation
2Device complexity
If simple frequency domain equalization is used in CMFB reception, then implementation complexity is reduced, but convergence speed deteriorates due to interchannel interference
Solution Approach 1:
The patent transitions from scalar frequency-domain equalization to matrix-based equalization, adding a dimensional aspect to handle interchannel interference. The matrix coefficients W(i) operate on the vector of received signals across multiple subchannels simultaneously, rather than processing each subchannel independently. This matrix approach maintains computational feasibility while significantly improving convergence speed by explicitly accounting for and compensating for interchannel interference effects that plague simple scalar equalizers
3Device complexity
If finite impulse response per-subchannel equalizers are used, then computational complexity is reduced, but performance in channels with significant frequency selectivity deteriorates
Solution Approach 1:
The patent merges the equalization processes across multiple subchannels into a unified matrix operation. Instead of using separate FIR equalizers for each subchannel, the invention combines them into a single matrix equalizer with coefficients W(i) that simultaneously process signals from all subchannels. This unified approach maintains lower computational complexity compared to optimal per-subchannel equalization while achieving superior error rate performance in frequency-selective channels by exploiting the statistical relationships between subchannels
Data Source
AI summary
The present invention is concerned with Cosine Modulated Filter Band modulation, in particular for a matrix equalizer for equalising a modulated signal carrying digital data, wherein the signal is modulated using a CMF6 and transmitted through a transmission channel having a channel impulse response c(t), wherein the matrix equalizer comprises: matrix coefficients W(i) determined based on the discrete-time matrix channel impulse response C(i) that is determined from the channel impulse response c(t); wherein the matrix equalizer is configured to equalize the modulated signal in order to reduce signal distortion introduced by the transmission channel. The present invention also concerns a method for equalising the CMFB modulated signal.