Heterogeneous WOLA Tone Processing for OFDM
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Solution Overview
Problem
Wireless communication systems face challenges in effectively suppressing out-of-band emissions and inter-symbol interference, particularly in heterogeneous networks where different services with varying sensitivity to interference are multiplexed, such as in next-generation 5G systems.
Innovation Solution
The technique involves processing OFDM or SC-FDMA symbols by dividing frequency tones into subsets and applying different weighted overlap-add (WOLA) processing parameters, with longer weighting lengths for edge tones and shorter lengths for center tones, to enhance out-of-band suppression and reduce inter-symbol interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If uniform WOLA processing with long weighting length is applied to all tones, then out-of-band suppression is improved, but inter-symbol interference increases
Solution Approach 1:
The patent applies different WOLA processing parameters to different subsets of frequency tones within the same symbol. Specifically, edge tones (first and second subsets) are processed with a first WOLA parameter providing longer weighting, while center tones (third subset) are processed with a second WOLA parameter providing shorter weighting. This local differentiation allows optimal suppression of out-of-band emissions at edges while minimizing inter-symbol interference for center tones.
2Object-generated harmful factors
If heterogeneous WOLA processing is applied to different tone subsets, then both out-of-band suppression and inter-symbol interference are optimized, but processing complexity increases
Solution Approach 1:
The patent segments the frequency tones of each symbol into three distinct subsets: first subset (edge tones), second subset (edge tones), and third subset (center tones). Each subset is then processed with appropriate WOLA parameters. This segmentation enables differentiated processing that optimizes both OOB suppression and ISI reduction while maintaining manageable complexity through systematic organization.
Solution Approach 2:
The patent changes the WOLA processing parameters (weighting length, window function type) based on the specific subset of tones being processed. Edge tones use parameters optimized for spectral containment, while center tones use parameters optimized for time-domain localization. This parameter adaptation allows each tone subset to be processed with optimal settings for its specific requirements.
Data Source
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AI summary
Techniques for processing of symbols (e.g., orthogonal frequency division multiplexing (OFDM) or single carrier-frequency division multiple access (SC-FDMA) symbols) provide enhanced out-of-band (OOB) suppression of the symbols and also provide reduced inter-symbol interference (ISI) between a symbol and a subsequent symbol. Multiple frequency tones of a symbol may be divided into two or more subsets of tones. For example, subsets of tones associated with a head portion or a tail portion of an OFDM symbol may be processed with a relatively long weighted overlap-add (WOLA) weighting length or filtering length, and a subset of tones associated with a center portion of the OFDM symbol may be processed with a relatively short WOLA weighting length or filtering length. Such heterogeneous processing of tones within a symbol may provide enhanced inter-channel interference (ICI) and improved OOB suppression and also provide reduced ISI for the center tones of the symbol.