Restricted Target Wake Time Coordination Between Access Points
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Solution Overview
Problem
Existing wireless communication systems face challenges in coordinating restricted target wake time (r-TWT) schedules between access points (APs) in different basic service sets (BSS) and overlapping BSS (OBSS), which affects latency-sensitive applications.
Innovation Solution
The implementation of r-TWT coordination between APs in a BSS and APs in an OBSS, where APs negotiate and agree on r-TWT schedules, and APs in the BSS respect the r-TWT schedules of APs in the OBSS by adjusting their transmission opportunities (TXOP) and using beacon frames, action frames, and RTS/CTS exchanges to ensure synchronization and clock drift adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If APs in different BSS and OBSS operate independently with their own r-TWT schedules, then each AP can maintain its own schedule flexibility, but interference occurs between overlapping schedules causing unpredictable latency
Solution Approach 1:
The patent merges r-TWT schedule information from multiple APs (both own AP and neighboring APs) into a coordinated schedule. APs exchange r-TWT setup frames containing their schedule parameters (service period start time, interval, duration) and negotiate non-overlapping time slots. This combining of schedule information from distributed APs resolves the latency predictability issue while managing coordination complexity through standardized frame exchange protocols.
2Loss of time
If APs negotiate and respect r-TWT schedules across BSS boundaries, then latency-sensitive applications achieve predictable performance, but the coordination mechanism increases system complexity
Solution Approach 1:
The patent implements preliminary action by having APs negotiate and establish r-TWT schedules in advance before actual data transmission occurs. APs exchange r-TWT setup frames to pre-coordinate service period timings, ensuring that latency-sensitive applications can immediately utilize the pre-negotiated time slots without additional negotiation overhead during actual transmission. This preliminary coordination reduces real-time latency while managing complexity through advance planning.
3Use of energy by moving object
If APs use traditional TWT schedules, then power efficiency is improved, but latency-sensitive applications cannot meet strict timing requirements
Solution Approach 1:
The patent applies local quality by creating different schedule characteristics for different application types. Within the same BSS or OBSS, latency-sensitive applications receive dedicated r-TWT service periods with strict timing guarantees (shorter intervals, guaranteed TXOP), while other applications can use traditional TWT schedules with more flexible timing. This localized differentiation allows simultaneous optimization for both power efficiency (traditional TWT) and latency (r-TWT) depending on application requirements.
Data Source
AI summary
A method and system for restricted target wake time (r-TWT) coordination where a first AP in a basic service set (BSS) respects an r-TWT schedule of a second AP, where the second AP is in an overlapping basic service set (OBSS). The first AP acquires the r-TWT schedule of the second AP and indicates to the second AP that the first AP respects the r-TWT schedule of the second AP. The first AP provides to a station associated with the first AP an indication of the r-TWT schedule of the second AP to cause a frame exchange with the STA of the first AP to end at a beginning of a r-TWT service period of the second AP to respect the r-TWT schedule of the second AP.