Coordinated Beamforming Sounding With Interference Rejection Feedback
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Solution Overview
Problem
Existing coordinated beamforming (C-BF) technologies fail when the number of receiver antennas exceeds the number of data streams, leading to performance degradation due to multi-user interference (MUI) and insufficient signal-to-noise ratio (SNR) in wireless networks with multiple access points (APs) and stations (STAs).
Innovation Solution
A multi-antenna non-AP station computes and provides feedback information to both its associated BSS AP and OBSS AP, using interference rejection combiners to ensure precoders for the OBSS AP are within the null space of the BSS AP's precoders, thereby mitigating MUI and maintaining optimal SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of receiver antennas exceeds the number of data streams, then the system can support more spatial diversity and beamforming capabilities, but multi-user interference increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies preliminary action by having the non-AP station compute the interference rejection combiner matrix W1 in advance, before receiving data from the OBSS AP. This pre-computed matrix is then used to process incoming signals, enabling the system to mitigate multi-user interference proactively rather than reactively, thus maintaining reliable SNR even when receiver antennas exceed data streams
Solution Approach 2:
The interference rejection combiner matrix W1 acts as an intermediary that processes the received signal by projecting it onto the null space of the BSS AP's channel matrix. This intermediate processing step separates the desired signal from interfering signals, allowing the system to utilize excess receiver antennas for improved spatial resolution without degrading SNR
2Object-affected harmful factors
If coordinated beamforming is implemented with multiple APs, then interference between overlapping BSSs is reduced, but the complexity of computing and coordinating precoders increases
Solution Approach 1:
The patent implements feedback by having the non-AP station send feedback information containing the precoder matrix Q2 to the OBSS AP. This feedback enables the OBSS AP to adjust its precoding to lie within the null space of the BSS AP's precoders, creating a coordinated beamforming system that reduces inter-BSS interference through iterative information exchange rather than complex centralized coordination
Solution Approach 2:
The patent segments the interference mitigation problem into two independent parts: the BSS AP focuses on optimizing its own precoder for its associated station, while the non-AP station computes the interference rejection combiner W1 based on the BSS AP's channel. This segmentation allows each entity to operate independently with reduced complexity, avoiding the need for complex joint optimization across all APs
Data Source
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AI summary
A non-AP station (120a) configured to communicate with a first BSS AP (110a) comprises a communication interface (123a) with a plurality of antennas (124a1-3) configured to receive first pilot signals from the first BSS AP (110a) and second pilot signals from a second OBSS AP (110b). The non-AP station (120a) further comprises a processing circuitry (121a) configured to estimate a first channel matrix based on the first pilot signals and a second channel matrix based on the second pilot signals and to determine, based on the first channel matrix, an interference rejection combiner matrix for suppressing a multi-user interference caused by the first BSS AP (110a). The communication interface (123a) is further configured to send first feedback based on the first channel matrix to the first BSS AP (110a) and second feedback based on the interference rejection combiner matrix and the second channel matrix to the second OBSS AP (110b).