C-RTWT Channel Access Coordination for Overlapping BSSs
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Solution Overview
Problem
Existing R-TWT scheduling is designed primarily for single BSS scenarios and fails to consider interference from Overlapping BSS (OBSS), leading to compromised prioritized channel access due to medium busy conditions during scheduled R-TWT SPs.
Innovation Solution
A Coordinated R-TWT (C-RTWT) process is introduced to prevent OBSS interference by implementing new channel access rules, including TXOP termination, overlapping quiet interval protection, and C-RTWT SP sharing for APs and non-AP STAs, considering network topology and device capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If R-TWT scheduling is implemented in single BSS, then channel access prioritization is improved, but interference from OBSS compromises the prioritized access
Solution Approach 1:
The patent merges single-BSS R-TWT scheduling with multi-BSS coordination by introducing OBSS ID negotiation and coordinated TXOP termination. Multiple BSSs share the same prioritized access mechanism while adding cross-BSS awareness through negotiation protocols, allowing simultaneous operation without interference.
Solution Approach 2:
The patent introduces an intermediary coordination mechanism between BSSs through the negotiation of OBSS IDs and coordinated TXOP termination signals. This intermediary layer enables BSSs to recognize and avoid interfering with each other's prioritized access periods without requiring direct BSS merging.
2Productivity
If TXOP termination is implemented at R-TWT SP starting point, then channel access for intended BSS is improved, but coordination complexity with OBSS increases
Solution Approach 1:
The patent applies preliminary action by having BSSs negotiate and pre-determine TXOP termination timing before the actual channel access period. The coordination parameters are established in advance through negotiation protocols, allowing automatic termination without real-time complex decision-making.
Solution Approach 2:
The patent changes the parameter of TXOP duration dynamically based on negotiated coordination parameters. By adjusting the effective TXOP length according to OBSS scheduling information, the system achieves efficient channel access while managing complexity through parameter-based control rather than complex algorithms.
3Reliability
If overlapping quiet interval is enforced, then interference protection is improved, but channel access time for non-R-TWT traffic is reduced
Solution Approach 1:
The patent applies local quality by making the quiet interval protection selective rather than universal. The protection is applied locally to specific BSS pairs that have negotiated coordination, allowing other BSSs to access the channel normally. This targeted approach maintains interference protection where needed while minimizing overall channel access time loss.
Data Source
AI summary
Controlling channel access for UHR devices performing a Coordinated-Restricted Target Wake Time (C-RTWT) to prevent interference between Service Periods (SPs) on overlapping BSSs (OBSS). The coordination mechanism creates different rules based on the type of network topology and scenarios detected. In one aspect, a back-to-back CF-End transmission is used to truncate the basic Network Allocation Vector (NAV) of the OBSS. New channel access rules control TXOP termination, overlapping quiet interval and C-RTWT SP sharing for stations across BSSs.