OFDM Receiver Pseudo-Extension Echo Management
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Solution Overview
Problem
Conventional digital transmission systems face limitations in efficiently equalizing multipath linear distortion, particularly in multi-carrier systems, due to the high computational requirements and inefficiencies of adaptive equalization techniques, which are exacerbated by the need for cyclic prefixes that reduce bandwidth efficiency and increase power consumption.
Innovation Solution
The implementation of a signal equalizing receiver that processes OFDM symbols using overlapped circular convolution or overlapped Fourier transforms, eliminating the need for cyclic prefixes by dynamically adjusting pseudo-extensions to match echo durations, thereby enabling effective equalization in both time and frequency domains without the overhead of cyclic prefixes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclic prefixes are used to equalize multipath linear distortion, then reliability is improved, but bandwidth efficiency deteriorates and power consumption increases
Solution Approach 1:
The patent extracts and removes the cyclic prefix from the OFDM signal structure, replacing it with a pseudo-extension that is only applied when needed for specific echo conditions. This eliminates the continuous overhead of cyclic prefixes while maintaining equalization capability through targeted use of pseudo-extensions based on measured echo durations.
Solution Approach 2:
The patent implements dynamic adjustment of the pseudo-extension length based on measured echo durations. Instead of using a fixed cyclic prefix length for all conditions, the system adapts the extension length to match the specific echo characteristics, optimizing both reliability and bandwidth efficiency for each transmission condition.
2Reliability
If cyclic prefixes are used to equalize multipath linear distortion, then reliability is improved, but power consumption increases
Solution Approach 1:
The patent removes the cyclic prefix overhead that continuously consumes power, replacing it with a pseudo-extension mechanism that is dynamically applied only when echo conditions require equalization. This reduces the baseline power consumption while maintaining the ability to handle multipath distortion when necessary.
Solution Approach 2:
The patent changes the parameter of extension length from a fixed cyclic prefix value to a dynamically adjusted pseudo-extension length based on measured echo characteristics. This parameter adaptation allows the system to minimize power consumption by using the minimum necessary equalization resources for each transmission condition.
3Productivity
If pseudo-extensions are used instead of cyclic prefixes, then bandwidth efficiency is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary measurement and control mechanism that determines when and how to apply pseudo-extensions. This intermediary layer measures echo durations and controls the application of pseudo-extensions, simplifying the overall process by making decisions based on measured conditions rather than requiring complex continuous equalization processing.
Solution Approach 2:
The patent performs preliminary measurement of echo durations before transmission, using these measurements to determine the appropriate pseudo-extension length in advance. This preliminary action simplifies the main processing by pre-determining the equalization parameters, reducing the complexity of real-time processing.
Data Source
AI summary
A receiver is configured to capture a plurality of linearly distorted OFDM symbols transmitted over a signal path. The receiver forms the captured OFDM symbols into an overlapped compound data block that includes payload data and at least one pseudo-extension, processes the overlapped compound block with circular convolution in the time domain using an inverse channel response, or frequency domain equalization, to produce an equalized compound block, and discards end portions of the equalized block to produce a narrow equalized block. The end portion corresponds with the pseudo-extension, and the narrow block corresponds with the payload data. The receiver cascades multiple narrow equalized blocks to form a de-ghosted signal stream of OFDM symbols. The OFDM symbols may be OFDM or OFDMA, and may or may not include a cyclic prefix, which will have a different length from the pseudo-extension.