Synchronized OBSS Interference Mitigation via Time-Division Coordination
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Solution Overview
Problem
In wireless communication systems, particularly in dense deployment environments using IEEE 802.11ax, overlapping basic service sets (OBSS) interference is exacerbated by uplink orthogonal frequency division multiple access (OFDMA) and multi-user multiple input multiple output (MU-MIMO), leading to reduced network efficiency due to inter-BSS interference types such as STA-to-STA, AP-to-AP, AP-to-STA, and STA-to-AP interference.
Innovation Solution
Implementing synchronized inter-BSS operation by aligning uplink and downlink transmissions between overlapping basic service sets, coordinating APs to divide wireless stations into groups, and applying specific interference mitigation schemes based on BSS geometry and station location to eliminate or minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If uplink OFDMA and MU-MIMO are implemented to increase network efficiency, then spectral density and throughput are improved, but inter-BSS interference is increased
Solution Approach 1:
The patent segments the overlapping BSSs into different groups based on their transmission timing. By dividing BSSs into groups that transmit during different time slots, the interference between them is reduced. This segmentation allows high-density deployments with OFDMA and MU-MIMO while managing interference through temporal separation of transmissions from different BSSs.
Solution Approach 2:
The patent implements periodic transmission patterns where BSSs alternate their transmission slots in a cyclic manner. Each BSS is assigned specific time periods during which it can transmit without interfering with other BSSs. This periodic action enables sustained high throughput through OFDMA and MU-MIMO while systematically managing inter-BSS interference through time-division multiplexing.
2Productivity
If APs are deployed in dense environments to increase network capacity, then network efficiency is improved, but OBSS interference is exacerbated
Solution Approach 1:
The patent introduces a temporal dimension to the spatial deployment of dense APs. Instead of only considering spatial arrangement, the patent assigns different time slots to BSSs in overlapping areas. This allows dense AP deployment for increased network capacity while using time-division to manage interference, effectively adding a time dimension to the network planning problem.
Solution Approach 2:
The patent implements dynamic transmission slot assignment where BSSs can flexibly adjust their transmission timing based on current network conditions and interference levels. This dynamic approach allows the network to adapt to changing traffic patterns and interference conditions, maintaining high efficiency in dense deployments while actively managing OBSS interference through real-time timing adjustments.
3Object-affected harmful factors
If synchronized UL and DL transmission is implemented to eliminate interference, then inter-BSS interference is reduced, but coordination complexity between APs is increased
Solution Approach 1:
The patent introduces a coordination mechanism where a designated master AP or central controller acts as an intermediary to manage timing synchronization between BSSs. This intermediary collects information from all BSSs, calculates optimal transmission slots, and distributes timing assignments. This approach reduces the coordination burden on individual APs while achieving the goal of synchronized transmission and interference reduction.
Solution Approach 2:
The patent implements feedback loops where APs report their transmission status and interference levels to the coordination mechanism. Based on this feedback, the timing assignments are dynamically adjusted to optimize interference reduction. This feedback-driven approach enables the system to achieve synchronized transmission and reduce inter-BSS interference while adapting to changing network conditions, managing the coordination complexity through iterative optimization.
Data Source
AI summary
A method of mitigating inter-BSS interference via synchronized inter-BSS operation is proposed. By aligning the transmission of UL and DL transmission in two overlapping OBSSs, the inter-BSS STA-to-STA and inter-BSS AP-to-AP types of interference can be eliminated. Furthermore, based on the BSS overlapping geometry and the STA location, different interference mitigation schemes can be applied to mitigate inter-BSS AP-to-STA and inter-BSS STA-to-AP types of interference.