Polyphase FFT Filter Bank Transmitter Module for Resilient OFDM
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Solution Overview
Problem
Existing broadband data transmission systems for radio communications face challenges in securing and resiliently transmitting RF signals, particularly in applications like police and military radio, where signals need to be difficult to detect and jam-proof.
Innovation Solution
The use of a transmitter and receiver module with a polyphase FFT filter bank, specifically a synthesis polyphase FFT filter bank for transmission and an analysis polyphase FFT filter bank for reception, employing Nyquist-filters and orthogonal frequency division multiplexing (OFDM) techniques to generate and process signals without oscillator adjustment times, ensuring robustness and interference resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oscillators are used for frequency adjustment in traditional OFDM transmitters, then frequency tuning is achieved, but signal loss occurs during oscillator setting time
Solution Approach 1:
The patent removes oscillators from the frequency tuning mechanism entirely. Instead of using oscillators that require setting time, the invention employs a polyphase FFT filter bank where filter units are directly associated with subcarriers, eliminating the oscillator setting time problem and preventing signal loss during frequency adjustment.
Solution Approach 2:
The patent replaces the mechanical oscillator-based frequency tuning system with a digital filter bank system. The polyphase FFT filter bank uses computational filtering instead of physical oscillator adjustment, substituting a mechanical/electrical system with a digital processing system that has no setting time.
2Device complexity
If traditional analysis filter banks are used in OFDM transmitters, then signal processing is simplified, but inter-symbol and inter-carrier interference occurs
Solution Approach 1:
The patent inverts the traditional OFDM architecture by placing the synthesis filter bank in the transmitter instead of the receiver. This reversal allows the filter units to be directly associated with subcarriers in the transmission path, preventing inter-symbol and inter-carrier interference before the signal is even transmitted, rather than trying to correct it after reception.
Solution Approach 2:
The synthesis filter bank performs preliminary signal conditioning and orthogonalization before transmission. By pre-processing the signal with properly designed filter units associated with each subcarrier, the system prevents interference from occurring in the first place, rather than dealing with it after the fact.
3Productivity
If signals are transmitted on all subcarriers, then bandwidth utilization is maximized, but interference between subcarriers increases
Solution Approach 1:
The patent associates specific filter units with specific subcarriers in a structured manner, where each filter unit has a localized frequency response centered on its associated subcarrier. This local quality assignment ensures that each subcarrier is cleanly separated in frequency, allowing all subcarriers to be utilized without mutual interference.
Solution Approach 2:
The frequency spectrum is segmented into distinct subcarrier channels, each handled by a dedicated filter unit. This segmentation approach allows the system to utilize the entire bandwidth by dividing it into non-interfering segments, with each segment processed independently by its associated filter unit.
Data Source
AI summary
A transmitter module for a broadband data transmission system for radio communications, comprising at least one polyphase FFT filter bank is described. The at least one polyphase FFT filter bank is established as a synthesis polyphase FFT filter bank, wherein the at least one polyphase FFT filter bank comprises several filter units, wherein the transmitter module is configured to generate a transmission signal by an orthogonal frequency division multiplexing technique, for example by a shaped orthogonal frequency division multiplexing. Moreover, a receiver module for a broadband data transmission system and a data transmission system are described.