f-OFDM Signal Processing Complexity Reduction
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Solution Overview
Problem
The complexity of digital shaping filtering in Filtered-OFDM (f-OFDM) technology is high due to the need for high-order filtering for out-of-band performance and broad signal bandwidths, which increases implementation complexity and delays, particularly in low-cost terminals and contradicts the ultra-low delay requirements of 5G services.
Innovation Solution
A signal processing method that divides the OFDM signal into a narrowband sideband signal and a broadband intermediate signal, applying high-order filtering to the sideband with a low sampling rate and low-order filtering to the intermediate signal with a high sampling rate, reducing overall filtering complexity by decoupling these aspects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-order digital shaping filter is used to perform OFDM subband filtering, then out-of-band performance is improved, but filtering complexity increases
Solution Approach 1:
The patent divides the broadband OFDM signal into multiple narrowband subband signals. Each subband is then processed with a low-order filter instead of applying a high-order filter to the entire broadband signal. This segmentation approach maintains the out-of-band performance while significantly reducing the filtering complexity for each individual subband.
Solution Approach 2:
The patent applies different filtering strategies to different parts of the signal spectrum. Narrowband subbands use low-order filters with appropriate filter orders adapted to their specific bandwidth requirements, while the overall system achieves the required out-of-band performance through the combination of multiple filtered subbands. This local optimization reduces overall complexity.
2Manufacturing precision
If high-order digital shaping filter is used at high sampling rate, then out-of-band performance is improved, but processing time increases
Solution Approach 1:
By segmenting the broadband signal into narrowband subbands, each processed at a reduced sampling rate, the patent reduces the processing time for each filter operation. The low-order filters operate faster on narrowband signals, and the parallel processing of multiple subbands further reduces overall processing time while maintaining out-of-band performance.
Solution Approach 2:
The patent changes the sampling rate parameter from high to low for each narrowband subband processing. This parameter change reduces the computational burden and processing time of the filtering operations while the combination of multiple subbands maintains the required out-of-band performance characteristics.
3Manufacturing precision
If high-order digital shaping filter is used, then transition band is narrowed, but implementation complexity increases
Solution Approach 1:
The patent segments the frequency spectrum into multiple narrowband subbands. Each subband requires a smaller transition band width to achieve the same absolute out-of-band performance, allowing the use of low-order filters with fewer coefficients. This segmentation approach narrows the required transition band for each filter while reducing implementation complexity.
Solution Approach 2:
The patent changes the filter order parameter from high to low for each narrowband subband. This parameter change reduces the number of filter coefficients and simplifies the implementation while the narrow bandwidth of each subband ensures that the absolute transition band width remains sufficient to meet performance requirements.
Data Source
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AI summary
The present invention relates to the field of communications technologies, and discloses a signal processing method and a device, to implement a filtering scheme with low complexity. The method includes: dividing an OFDM signal into a first sideband signal, a first signal, and a second sideband signal; sampling the first sideband signal by using a first sampling rate, and performing filtering processing of a first spectral mask, upsampling processing, and digital frequency conversion processing on a sampled signal, to generate a first f-OFDM signal; sampling the first signal by using a second sampling rate, and performing filtering processing of a second spectral mask on a sampled signal, to generate a second f-OFDM signal; sampling the second sideband signal by using a third sampling rate, and performing filtering processing of a third spectral mask, upsampling processing, and digital frequency conversion processing on a sampled signal, to generate a third f-OFDM signal; and superposing the first f-OFDM signal, the second f-OFDM signal, and the third f-OFDM signal to obtain an f-OFDM signal, where the first sampling rate and the third sampling rate are both less than the second sampling rate.