Access Point Interference Suppression via Selective Receiver Path Attenuation
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Solution Overview
Problem
High-density wireless local area network (WLAN) deployments experience significant co-channel interference between access points, which limits the number of clients per access point and degrades signal quality due to strong AP-to-AP interference, especially in the 2.4 GHz frequency band, forcing a trade-off between AP transmit power and interference suppression.
Innovation Solution
Access points in high-density WLAN deployments employ cooperative adjustment of MIMO configuration, transmit pre-coding, and dynamic adjustment of receive start-of-packet and clear channel assessment thresholds to create a null-space between co-channel access points, selectively disabling or attenuating receiver paths to reduce AP-to-AP interference while maintaining sufficient dimensionality for client transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AP transmit power is increased to improve downlink signal quality, then signal-to-noise ratio at client is improved, but AP-to-AP co-channel interference increases
Solution Approach 1:
The patent applies local quality by selectively disabling or attenuating specific receiver paths at each access point based on the local interference environment. Each AP identifies which receiver paths are most affected by co-channel interference from neighboring APs and selectively disables those paths, while maintaining full reception capability on other paths. This localized approach allows each AP to optimize its reception quality without uniformly reducing performance across the entire network.
Solution Approach 2:
The patent changes the parameter of receiver path activation state from a fixed configuration to a dynamic state that can be adjusted based on interference conditions. By selectively enabling or disabling receiver paths, the system changes the effective receive antenna configuration to create nulls in directions of interfering APs. This parameter change allows the system to adapt to varying interference conditions and maintain optimal performance.
2Quantity of substance
If AP-to-AP spacing is reduced to increase network density, then number of clients per AP is restricted, but co-channel interference between APs increases
Solution Approach 1:
The patent enables high-density deployment by allowing each AP to locally adapt its receiver configuration to the specific interference pattern created by nearby APs. Each AP independently identifies and disables the receiver paths that would be most affected by interference from specific neighboring APs, while maintaining full functionality on other paths. This local adaptation enables dense packing of APs without proportionally increasing interference impact.
Solution Approach 2:
The patent introduces dynamics to the receiver configuration by allowing APs to selectively enable or disable receiver paths based on real-time interference conditions. This dynamic adjustment of receiver configuration allows the network to adapt to changing spatial relationships and interference patterns as APs are added or moved, enabling flexible high-density deployment scenarios.
3Object-generated harmful factors
If receiver paths are selectively disabled to suppress interference, then AP-to-AP interference is reduced, but channel dimensionality for client transmissions is reduced
Solution Approach 1:
The patent applies local quality by making interference suppression selective rather than uniform. Each AP independently determines which receiver paths to disable based on the specific interference sources present in its local environment. This selective approach ensures that receiver paths needed for serving local clients remain active, while only paths affected by external interference are disabled. The local decision-making process preserves channel dimensionality for client transmissions while suppressing interference from other APs.
Data Source
AI summary
In a wireless local area network, each of multiple access points, in a high density deployment, are configured to suppress co-channel interference. A first access point having a plurality of antennas beamforms a transmission to a wireless client device within a null-space or with the weakest singular eigenmodes of a wireless channel between the first access point and at least one co-channel second access point. Techniques are presented herein for situations in which any given access point has two or more co-channel access points. In addition, an access point may perform receive side suppression with respect to a transmission (made by a co-channel access point to one of its associated wireless client devices) that is received from that co-channel access point.