MIMO Precoder Feedback Compression via Channel Correlation
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Solution Overview
Problem
Conventional MIMO communication systems face challenges in reducing precoding feedback rates and minimizing uplink performance loss and feedback delay due to limited feedback resources and high data rates.
Innovation Solution
The system compresses precoder feedback by exploiting channel correlation in time and frequency, using techniques such as temporal compression and run-length coding to reduce redundancy, allowing feedback only when precoder states change, and limiting the number of clusters for which feedback is sent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MIMO systems transmit full precoding feedback, then communication accuracy is maintained, but feedback data rate becomes excessively high and consumes limited feedback resources
Solution Approach 1:
The patent extracts and transmits only the essential precoding feedback information - specifically the precoder index indicating the selected precoding matrix - rather than transmitting complete channel state information. This extraction approach maintains the necessary communication accuracy while dramatically reducing the feedback data rate and resource consumption.
Solution Approach 2:
The patent changes the parameter representation by quantizing continuous channel state information into discrete precoder indices from a codebook. This parameter transformation reduces the feedback burden while maintaining sufficient accuracy for effective precoding operations in MIMO systems.
2Quantity of substance
If precoding feedback is compressed to reduce data rate, then feedback resources are conserved, but uplink performance loss increases
Solution Approach 1:
The patent applies preliminary action by having the receiver select the optimal precoding matrix from the codebook based on channel state information before feedback transmission. This pre-selection ensures that the compressed precoder index feedback maintains accuracy while reducing data rate, thereby conserving feedback resources without significant uplink performance loss.
3Measurement precision
If complete precoding feedback is transmitted frequently, then channel accuracy is maintained, but feedback delay increases due to limited feedback resources
Solution Approach 1:
The patent extracts only the critical precoder index information for feedback transmission rather than complete channel state information. This extraction enables more frequent and timely feedback updates within limited resource constraints, reducing feedback delay while maintaining sufficient channel accuracy for effective precoding.
4Quantity of substance
If codebook-based precoding is used to reduce feedback, then feedback data rate is reduced, but the multiplicity of precoder coefficients still overwhelms limited feedback bandwidth
Solution Approach 1:
The patent changes the feedback parameter from multiple precoder coefficients to a single precoder index that identifies the selected precoding matrix from the codebook. This parameter transformation dramatically reduces feedback data rate and simplifies feedback processing, eliminating the overwhelming complexity associated with transmitting multiple coefficients while maintaining effective precoding capability.
Data Source
AI summary
In a closed-loop wireless communication system, a codebook-based precoding feedback compression mechanism is provided to remove redundancy from the precoding feedback that is caused by channel correlation in time and frequency. Redundancy due to temporal correlation of the transmission channel is removed by sending precoding feedback only if there is a change in the precoder state for the channel to the receiver. Redundancy due to frequency correlation is removed by run length encoding the precoding feedback, thereby compressing the precoding feedback prior in the frequency domain. By compressing the precoding feedback, the average rate of precoder feedback is reduced.