MIMO Channel Estimation via OBSS Interference Feedback
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Solution Overview
Problem
In WLAN systems, the natural variability of the wireless channel causes Channel State Information (CSI) to age, leading to loss of beamforming gain and interference cancellation, necessitating frequent sounding sequences, which waste channel capacity if excessive and degrade performance if insufficient.
Innovation Solution
The proposed solution coordinates overlapping Access Points (APs) in an Overlapping Basic Service Set (OBSS) scenario, using wireless device positions and transmission times to distinguish between outdated CSI and OBSS interference, thereby accurately determining the need for new sounding sequences, reducing unnecessary sounding and minimizing polluted CSI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent sounding sequences are performed to refresh CSI, then beamforming gain and interference cancellation are maintained, but channel capacity is wasted
Solution Approach 1:
The system uses feedback from wireless devices about observed interference levels to determine whether CSI refresh is needed. The access point receives interference measurements from devices and uses this feedback to intelligently trigger sounding sequences only when necessary, rather than performing frequent periodic sounding.
Solution Approach 2:
Wireless devices autonomously measure and report interference levels to the access point, enabling the system to self-monitor channel conditions and trigger CSI refresh only when actual interference is detected, rather than relying on predetermined periodic scheduling.
2Reliability
If sounding sequences are performed frequently to maintain CSI accuracy, then beamforming performance is maintained, but throughput decreases due to channel capacity consumption
Solution Approach 1:
The access point receives interference measurements from wireless devices and uses this feedback to intelligently trigger sounding sequences only when actual interference is detected, optimizing the balance between maintaining beamforming performance and preserving throughput.
Solution Approach 2:
Instead of performing frequent periodic sounding, the system performs partial sounding actions only when necessary - triggered by actual interference observations from devices, thereby avoiding excessive channel capacity consumption while maintaining adequate beamforming performance.
3Reliability
If the access point initiates sounding sequences without accurate channel condition knowledge, then CSI may be refreshed, but polluted CSI is received due to undetected OBSS interference
Solution Approach 1:
Wireless devices perform preliminary interference measurements and report findings to the access point before the access point initiates sounding sequences. This preliminary action provides advance knowledge of channel conditions, preventing the access point from triggering sounding when interference is already present.
Solution Approach 2:
The system implements feedback from wireless devices about observed interference levels, allowing the access point to evaluate whether the channel is suitable for accurate CSI measurement before initiating sounding sequences, thereby avoiding polluted CSI reception.
4Reliability
If the access point cannot distinguish between outdated CSI and OBSS interference, then unnecessary sounding is performed, but channel capacity is wasted
Solution Approach 1:
Wireless devices provide feedback about observed interference levels, enabling the access point to distinguish between performance degradation caused by outdated CSI versus actual OBSS interference, thereby triggering sounding only when CSI is actually outdated rather than when interference is present.
Solution Approach 2:
Wireless devices act as intermediaries that measure and report channel conditions to the access point, providing the access point with accurate information about whether performance issues stem from outdated CSI or from external OBSS interference, enabling informed decisions about when to initiate sounding.
Data Source
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AI summary
The present disclosure relates methods, a device and a system for evaluation of channel estimate. One method is performed in a first access point 110a arranged to communicate with one or more wireless devices 10a, 10b through information streams that are created using multiple co-located antennas. The method comprises transmitting S1 or receiving S1b a packet A, to/from, the first wireless device 10a, wherein the packet A is transmitted using a precoder determined using the channel estimate, retrieving S4 information about possibly interfering transmissions C between further access points 110b in the vicinity of the first access point 110a, and respective second wireless devices 10c, 10d; wherein the information comprises location information and timing information related to the possibly interfering transmissions, determining S5 spatial separations between the transmissions A and C and evaluating S7 the channel estimate, based on the determined spatial separations.