Restricted TWT Scheduling for Multi-Link WLAN Interference

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current wireless local area network (WLAN) technologies face challenges in supporting restricted Target Wake Time (TWT) operation for multi-link devices (MLDs), particularly in environments with non-simultaneous transmit/receive (NSTR) link pairs, which can disrupt latency-sensitive applications due to interference and alignment issues during restricted TWT service periods.

Innovation Solution

The implementation of a framework that enables restricted TWT operation across multiple links between Access Point (AP) MLDs and non-AP MLDs, using broadcast TWT schedules and Quiet elements to protect restricted TWT service periods, and aligning service periods across links to prevent interference, while allowing flexible TWT parameter configurations to manage conflicts and optimize channel access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If restricted TWT operation is implemented on multiple links, then power efficiency and latency are improved, but interference and alignment issues occur in NSTR link pairs

Engineering Contradiction:

ImprovelatencyVSAvoidinterference

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The patent segments the TWT operation by introducing a restricted TWT service period (SP) that is specifically allocated for latency-sensitive traffic on NSTR link pairs. This segmentation allows the system to isolate and protect time-critical communications from interference caused by simultaneous transmissions on other links, thereby reducing latency without causing harmful interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by establishing TWT wake time negotiations and scheduling restrictions before the actual data transmission occurs. The AP and non-AP MLD pre-negotiate wake times and the non-AP MLD pre-configures its radios to restrict operation to only those links designated for restricted TWT during the protected service periods, preventing interference before it can occur.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If TWT wake time negotiation is performed, then power efficiency is improved, but latency-sensitive applications are affected due to delay between DL traffic arrival and TWT service period start

Engineering Contradiction:

Improvepower efficiencyVSAvoiddelay

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent applies local quality by creating differentiated TWT service periods: restricted TWT SPs for latency-sensitive applications with shorter wake intervals and tighter timing, and regular TWT SPs for other traffic. This allows the system to optimize power efficiency for general traffic while providing low-latency service for time-critical applications through localized scheduling adjustments.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes parameter changes by allowing the non-AP MLD to dynamically adjust TWT parameters (such as wake interval, service period duration, and traffic indication window) based on the specific requirements of different applications. For latency-sensitive traffic, the system configures shorter intervals and earlier wake times, while for other traffic, longer intervals optimize power savings.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If broadcast TWT schedule is applied to multiple links, then channel access efficiency is improved, but interference occurs in NSTR link pairs

Engineering Contradiction:

Improvechannel access efficiencyVSAvoidinterference

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements preliminary anti-action by pre-restricting the operation of radios on NSTR link pairs to only those links designated for restricted TWT during protected service periods. This preliminary restriction prevents the radio from transmitting or receiving on non-restricted links during the protected window, proactively counteracting the interference that would otherwise be generated by simultaneous transmissions.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent introduces an intermediary mechanism through the restricted TWT service period configuration, which acts as a mediator between the need for efficient multi-link channel access and the requirement to prevent interference in NSTR pairs. The restricted SP configuration serves as an intermediate layer that coordinates channel access across links, allowing efficient utilization while maintaining isolation where needed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20240381265A1Restricted TWT operations for multi-link devices

Publication Date: 2024.11.14 SAMSUNG ELECTRONICS CO LTD

AI summary

Embodiments of the present disclosure provide methods and apparatuses for facilitating restricted target wake time (TWT) operation in a wireless local area network. The apparatuses include a non-access point (AP) multi-link device (MLD) comprising a plurality of stations (STAs) and a processor. Each STA comprises a transceiver configured for broadcast TWT operation on multi-link operation (MLO) links with corresponding APs of an AP MLD. The processor is operably coupled to the transceivers, and configured to negotiate a broadcast TWT schedule over a first link between a first STA and a first AP of the AP MLD, apply the broadcast TWT schedule to the group of links, negotiate a restricted TWT schedule with the AP MLD over at least one link of the group of links, and establish the restricted TWT schedule on one or more links of the at least one link.