Co-State MAP Trellis for QLM Demodulation Complexity
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Solution Overview
Problem
Current communication technologies face limitations in achieving high data rates while maintaining reliable transmission over noisy channels, particularly in satellite, airborne, and wireless communications, as they are constrained by the Nyquist rate and Shannon capacity bounds.
Innovation Solution
The introduction of a co-state maximum a-posteriori MAP demodulation architecture and quadrature layered modulation (QLM) for OFDM and SC-OFDM modulations, which increases data rates by layering data symbol tones at frequency or time offsets, allowing for multiple layers of communication beyond the traditional Nyquist rate and Shannon bounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional modulation schemes (OFDM, SC-OFDM) are used, then system compatibility and ease of implementation are maintained, but data rate is limited by Nyquist rate and Shannon capacity bounds
Solution Approach 1:
The patent segments the modulation process into multiple independent layers (quadrature layers), where each layer carries a portion of the data stream. This segmentation allows the system to achieve higher aggregate data rates by combining multiple layers, while each individual layer can use conventional demodulation techniques, thus managing complexity through modular processing
Solution Approach 2:
The patent introduces an additional dimension to the modulation space by using quadrature layered modulation, where data is transmitted across multiple layers in the frequency or time domain. This dimensional expansion allows the system to exceed traditional Nyquist rate limitations without proportionally increasing the complexity of individual layer processing
2Productivity
If higher order modulations are used to increase data rate, then productivity improves, but reliability and bit error rate performance deteriorate in noisy channels
Solution Approach 1:
By segmenting the high-rate data stream into multiple lower-rate layers, each layer can use more robust modulation schemes that are less susceptible to noise. This segmentation allows the system to achieve high aggregate data rates while maintaining better error performance on each individual layer compared to using a single high-order modulation
Solution Approach 2:
The patent creates a composite modulation scheme by combining multiple modulation layers (quadrature layers), similar to how composite materials combine different materials to achieve superior properties. This composite approach allows the system to achieve both high data rates and improved reliability by leveraging the strengths of each individual layer
Data Source
AI summary
This invention discloses a new Co-State Maximum A-Posterior (MAP) trellis algorithm for implementing Quadrature Layered Modulation (QLM) demodulation over multiple layered channels. This MAP trellis algorithm has been demonstrated to provide performance which is at least as good as the current Maximum Likelihood (ML) trellis algorithm and to support a considerable reduction in the number of trellis paths to reduce the computational complexity. Computational complexity prevents ML trellis demodulation of higher order data symbol metrics over multiple layered channels since there is no viable means to support fewer trellis paths. MAP algorithms for reduction of trellis paths are disclosed for data symbol waveforms representative of OFDM, SC-OFDM, satellite, media, wire, and optical communications. QLM waveforms have mainlobes in time/frequency approximating square pulse mainlobes and have sidelobes which are relatively low to facilitate using iterative MAP trellis algorithms which include both mainlobes and sidelobes.