Wireless OFDM Beamforming Feedback Compression
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Solution Overview
Problem
In wireless OFDM communication systems, the feedback of beamforming information for transmit beamforming is limited by high overhead, particularly in wideband channels like those in the 60 GHz band, due to the need for low data rate feedback channels and repeated updates as channels change.
Innovation Solution
A receiving device and method that compresses beamforming information by selecting a reduced set of subcarriers or taps based on an error criterion, reducing the feedback overhead by exploiting characteristics in the frequency or time domain, and reconstructing the full beamforming information at the transmitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete beamforming information for all subcarriers is fed back to the transmitter, then the data link performance is maintained, but the feedback overhead becomes excessively high
Solution Approach 1:
The patent segments the complete beamforming information across all subcarriers into a reduced set of representative subcarriers. Instead of feedback for every subcarrier, the system selects and feeds back beamforming information only for selected representative subcarriers, thereby dividing the feedback task into manageable segments that reduce overall overhead while preserving essential channel characteristics
Solution Approach 2:
The patent creates a compressed representation (copy) of the complete beamforming information by selecting representative subcarriers. The transmitter then reconstructs the full beamforming information from this reduced set through interpolation or extrapolation, effectively using a simplified copy to represent the complete dataset without transmitting all original information
2Measurement precision
If beamforming information is fed back frequently to account for channel changes, then the beamforming accuracy is maintained, but the feedback overhead increases
Solution Approach 1:
The patent applies partial action by transmitting only the essential portion of beamforming information needed to maintain acceptable performance. Instead of feeding back complete information for all subcarriers, the system transmits a reduced set that captures the most critical channel variations, achieving sufficient accuracy without excessive feedback
3Quantity of substance
If beamforming information is compressed by selecting reduced set of subcarriers, then the feedback overhead is reduced, but the information completeness decreases
Solution Approach 1:
The patent changes the parameters of beamforming information representation by selecting representative subcarriers based on channel characteristics. The system transforms the complete frequency-domain beamforming information into a reduced set using selection criteria that preserve essential channel properties, thereby maintaining information completeness in a compressed form
Solution Approach 2:
The reduced set of representative subcarriers acts as an intermediary between the complete beamforming information and the feedback channel. This intermediate representation captures the essential channel characteristics while reducing data volume, serving as a bridge that preserves necessary information without requiring complete data transmission
Data Source
AI summary
A receiving device for use in a wireless OFDM communication system comprises two or more receive antennas for receiving OFDM signals received over a channel from a transmission device having two or more transmit antennas and applying transmit beamforming, and circuitry configured to perform channel estimation to estimate the channel, generate transmit beamforming information based on the channel estimation, the transmit beamforming information comprising beamforming information per subcarrier or time domain tap, determine a reduced set of transmit beamforming information from the transmit beamforming information, wherein the reduced set comprises beamforming information for a reduced set of subcarriers in the frequency domain or for a reduced set of taps in the time domain, wherein the subcarriers of the reduced set or the taps of the reduced set are determined based on an error criterion, and feed back the reduced set of transmit beamforming information to the transmission device.