Subband-Wise Combining for Low-Complexity Wireless Diversity
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Solution Overview
Problem
Conventional antenna diversity systems require full receiver and baseband signal paths for each antenna, leading to increased complexity, cost, and power consumption, and may not provide sufficient diversity gain in channels with frequency-selective fading.
Innovation Solution
A wireless diversity receiver with N signal processing paths, including a bin-wise combiner and an inverse transformation module, that downconverts RF signals, transforms them into subbands, combines subbands, and performs inverse transformation to generate a time-domain signal, using techniques like MRC and cophasing to account for phase and SNR differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antenna diversity systems use full receiver and baseband signal paths for each antenna, then diversity gain is achieved, but device complexity and power consumption increase significantly
Solution Approach 1:
The patent combines multiple antenna signals at the RF front end using analog combining circuits before the signals enter the baseband processor. This merging approach allows multiple diversity paths to be processed through a single shared baseband chain, eliminating the need for separate receiver paths for each antenna while maintaining diversity gain through coherent combining of the RF signals.
Solution Approach 2:
The patent implements a shared baseband processing chain that serves multiple antenna inputs. The single baseband processor handles signals from all diversity antennas through analog combining, making the baseband resources universal and multi-functional rather than dedicated to each antenna path, thus reducing overall system complexity.
2Reliability
If conventional antenna diversity systems use full receiver paths for each antenna, then signal quality is maintained, but power consumption increases
Solution Approach 1:
By merging multiple antenna signals at the RF front end through analog combining circuits and processing them through a single shared baseband chain, the patent eliminates redundant power-consuming components in parallel baseband processors while maintaining signal quality through coherent signal combination before digital conversion.
3Device complexity
If single-band MRC technique is used to reduce complexity, then device complexity is reduced, but diversity gain is insufficient in frequency-selective fading channels
Solution Approach 1:
The patent segments the frequency spectrum into multiple subbands using FFT processing. Each subband is processed independently with its own combining weights calculated based on channel conditions. This segmentation allows the system to adapt to frequency-selective fading by applying different combining strategies to different frequency regions, thereby maintaining high diversity gain while using a single shared baseband chain.
Solution Approach 2:
The patent dynamically changes combining parameters (weights and phases) for each subband based on estimated channel conditions. By adapting the combining parameters to match the frequency-selective fading characteristics, the system optimizes diversity gain for each subband independently, achieving performance comparable to full diversity receivers while using simplified analog combining hardware.
4Measurement precision
If full diversity receiver with individual equalization is used, then signal processing accuracy is optimized, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple antenna signals through analog combining circuits before digital conversion, requiring only a single baseband processor and modem. This merging architecture dramatically reduces the number of expensive components needed compared to full diversity receivers with separate processing chains, while maintaining signal processing accuracy through subband-wise combining and equalization applied to the combined signal.
Data Source
AI summary
A wireless diversity receiver includes, in part, N signal processing paths, a bin-wise combiner, and an inverse transformation module. Each signal processing path includes, in part, a mixer adapted to downconvert a frequency of an RF signal received by that path, an analog-to-digital converter adapted to convert the downconverted signal from an analog signal to a digital signal, and a transformation block adapted to transform the digital signal represented in time domain to an associated frequency domain signal having M subband signals. The bin-wise combiner is configured to combine the corresponding subband signals of the N paths. The inverse transformation block is configured to transform the output of the bin-wise combiner to an associated time-domain signal.