RID-Based TIM and Backoff for Supporting More Wireless Stations
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Solution Overview
Problem
The existing 802.11 standards are limited in supporting more than 2007 stations (STAs) due to the maximum size of the traffic indication map (TIM) element, leading to increased beacon frame overhead and inefficiencies in channel contention, especially in systems with a large number of devices like 802.11ah, which requires supporting up to 6000 STAs.
Innovation Solution
Implementing a Registered-State Based (RSB) Power Save (PS) mode with a new RID-based TIM element and power saving mechanism that uses Registration Identifiers (RIDs) to group STAs, allowing for efficient traffic indication and reduced channel contention through controlled contention periods with adjusted backoff values and group scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the maximum size of the TIM element is increased to support more STAs, then the number of supported STAs increases, but the beacon frame overhead increases
Solution Approach 1:
The patent divides the TIM element into multiple segments or parts, allowing the TIM information to be distributed across multiple smaller units rather than contained in a single large element. This segmentation enables support for more STAs while keeping each individual TIM element or transmission unit manageable in size, thus reducing the overhead impact of each beacon frame.
2Quantity of substance
If the TIM element size is increased to accommodate more STAs, then more STAs can be indicated, but the beacon frame transmission time increases
Solution Approach 1:
The patent implements a periodic mechanism where TIM information is transmitted in cycles or intervals rather than requiring all STAs to be indicated in every single beacon frame. This periodic action allows the system to rotate through different sets of STA indications across multiple beacon intervals, effectively supporting a larger total number of STAs while maintaining reasonable transmission time per beacon frame.
3Use of energy by moving object
If traditional power saving mechanisms are used with TIM-based indication, then power saving is achieved, but channel contention efficiency deteriorates with large number of STAs
Solution Approach 1:
The patent applies preliminary action by having the AP pre-assign specific resource units, time slots, or contention parameters to STAs based on their TIM indication status. Before STAs engage in channel contention, the system has already prepared and allocated resources in advance, which streamlines the contention process and improves efficiency when many STAs are simultaneously indicated in the TIM element.
Solution Approach 2:
The patent introduces an intermediary mechanism or intermediate step between TIM indication and channel contention. This intermediary could be a preliminary allocation phase, a scheduling step, or a coordination mechanism that processes the TIM information and prepares appropriate contention parameters before STAs actually contend for the channel, thereby improving overall efficiency.
Data Source
AI summary
A method for receiving a backoff value at a wireless station is presented. A traffic indication map is received at the station, wherein a backoff number is implicitly assigned to the station based on a position of the station within the traffic indication map. The backoff value is determined by multiplying the backoff number by a predetermined time value.