WLAN Access Point TIM Scheduling for Contention Reduction
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Solution Overview
Problem
In dense wireless local area network (WLAN) environments, the performance of WLANs is degraded due to contention among different types of terminals, such as legacy and high-throughput terminals, leading to inefficient channel access and power saving issues, particularly in frequency bands like 2.4 GHz and 5 GHz.
Innovation Solution
A method is introduced to schedule transmission intervals based on terminal types, using an enhanced traffic indicator map (TIM) frame, where high-throughput terminals like 11ac and 11ax perform transmissions in different intervals from legacy terminals, reducing contention and optimizing power saving efficiency by allocating same-type stations to the same TIM broadcast interval and employing downlink orthogonal frequency division multiple access (OFDMA) scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If all terminals transmit at the same beacon transmission point in time, then channel access is simplified, but contention increases and network performance degrades
Solution Approach 1:
The patent segments the transmission opportunity by dividing terminals into different groups (first group and second group) with different wake-up times. Terminals in the first group wake up at the beacon transmission point in time, while terminals in the second group wake up at a different point in time, thereby segmenting the contention and reducing collisions.
Solution Approach 2:
The patent introduces dynamic timing adjustment by allowing terminals to operate with different wake-up intervals based on their group assignments. The access point dynamically manages transmission schedules for different terminal groups, creating a dynamic time-division multiplexing scheme that adapts to terminal types and traffic conditions.
2Adaptability or versatility
If legacy terminals and high-throughput terminals transmit in the same interval, then device compatibility is maintained, but transmission efficiency decreases due to collisions
Solution Approach 1:
The patent segments terminals based on their capabilities and traffic characteristics, creating distinct transmission groups. Legacy terminals and high-throughput terminals are assigned to different groups with different wake-up times, allowing each group to transmit without interference from the other, thereby improving overall transmission efficiency while maintaining compatibility.
Solution Approach 2:
The patent applies different transmission schedules and wake-up times to different terminal groups based on their specific requirements. High-throughput terminals with urgent traffic are assigned different intervals compared to legacy terminals, providing localized optimization for each terminal type's performance characteristics.
3Use of energy by moving object
If power saving terminals transmit PS-polls at beacon transmission points, then power saving is achieved, but channel contention increases suddenly
Solution Approach 1:
The patent segments power-saving terminals into different wake-up groups, so that not all terminals transmit PS-polls simultaneously at beacon transmission points. By assigning different wake-up times to different groups, the patent maintains power-saving benefits while distributing channel access requests over time, reducing sudden contention spikes.
4Device complexity
If transmission intervals are not differentiated by terminal type, then system complexity is reduced, but network performance degrades in dense environments
Solution Approach 1:
The patent implements segmentation of terminals into manageable groups with distinct transmission schedules. This structured approach to differentiation provides a systematic method for managing diverse terminal types, balancing the increased scheduling complexity with significant improvements in network performance by reducing collisions and improving channel utilization.
Data Source
AI summary
Provided is a wireless communication method performed at an access point to enhance the transmission efficiency in a wireless local area network (WLAN) system, the method including scheduling a transmission time of an enhanced traffic indicator map (TIM) frame based on a type of a station, and transmitting a second beacon including the enhanced TIM frame to the station at a point in time aside from a transmission point in time of a first beacon.