Frequency Domain Channelization Reducing Analog Chain Complexity
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Solution Overview
Problem
Conventional MF-TDMA systems face inefficiencies due to homogeneous bandwidth-time plans and excessive margins for rain fading, leading to penalization of remote stations in clear skies, and require multiple analog chains and ADCs for multi-carrier channelization in the time domain.
Innovation Solution
A method and apparatus for decoding and channelizing digitally encoded signals using master matched filter coefficients, frequency domain channelization, and burst reconstruction, enabling efficient processing and adaptive modulation and coding schemes based on channel conditions without the need for multiple analog chains and ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple analog chains and ADCs are used for multi-carrier channelization in the time domain, then channelization capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple channelization functions into a single ADC by implementing frequency domain channelization using FFT processing. Instead of requiring separate analog chains and ADCs for each carrier, the system uses one ADC to capture the entire multi-carrier signal and then separates channels digitally in the frequency domain, dramatically reducing hardware complexity while maintaining multi-carrier channelization capability
Solution Approach 2:
The patent replaces the mechanical/analog approach of multiple physical chains and ADCs with a digital signal processing approach. The channelization that was previously performed in the time domain using analog filtering is substituted with frequency domain processing using FFT and IFFT operations, eliminating the need for complex analog hardware while achieving the same channel separation function
2Ease of manufacture
If homogeneous bandwidth-time plans with same MODCOD and symbol rate are used for all frequency channels, then system design is simplified, but spectral efficiency decreases and clear sky remotes are penalized
Solution Approach 1:
The patent enables different MODCOD and symbol rate configurations for different frequency channels by implementing heterogeneous bandwidth-time plans. Each channel can be independently configured based on its specific channel conditions, allowing clear sky remotes to use higher efficiency modulations while rain-affected channels use more robust modulations, thereby optimizing overall spectral efficiency while maintaining design feasibility through systematic configuration
3Reliability
If systems are designed to handle worst case link with rain fading, then reliability is improved, but clear sky remotes have excessive margins and performance is penalized
Solution Approach 1:
The patent applies different link margin allocations to different channels based on their specific propagation conditions. Channels experiencing rain fading are allocated excessive margins for reliability, while clear sky channels are allocated minimal margins for optimal performance. This localized margin allocation is enabled by the frequency domain channelization that allows independent processing and configuration of each channel
Data Source
AI summary
A method of decoding a digitally encoded signal having plural channels includes sampling a transient portion of a master filter mask, storing matched filter coefficients obtained from the sampling, receiving the digitally encoded signal, channelizing the digitally encoded signal into the plural channels, and generating a channel matched filter mask for each one of the plural channels using a subset of the stored coefficients. The method also includes filtering each one of the plural channels, in the frequency domain, based on the channel matched filter mask generated for each of the plural channels. Also disclosed are related methods using a burst reconstruction buffer, per channel distortion equalization, channel estimation and activity monitoring, and noise floor estimation, as well as corresponding apparatuses.