Sectorized WLAN Beacon Transmission Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current IEEE standards do not adequately define beacon transmission methodologies for sectorized access points with directional antennae, leading to inefficient neighbor discovery and traffic scheduling in wireless local area networks, resulting in unnecessary re-transmissions and power drain.
Innovation Solution
Implementing a method where access points transmit beacons on different sectors at predictable times and announce sector beacon transmission times and channel numbers to clients, allowing for efficient sector discovery and inter-sector handoff by using virtual Target Beacon Transmission Times (TBTT) and Sector Information Elements (IEs) to facilitate client synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sectorized APs with directional antennae are used to improve spatial efficiency and capacity, then network capacity and coverage are improved, but beacon transmission scheduling becomes undefined and complex
Solution Approach 1:
The patent segments the beacon transmission process by introducing sector-specific TBTT values and sector information elements. Each sector of a directional AP is assigned its own TBTT, allowing independent scheduling of beacon transmissions across different spatial sectors. This segmentation resolves the scheduling complexity by treating each sector as an independent transmission unit with its own timing parameters.
Solution Approach 2:
The patent introduces dynamic beacon interval adjustments for different sectors. The AP can configure different beacon intervals for different sectors based on traffic requirements, client associations, and interference conditions. This dynamic approach allows the system to adapt beacon scheduling to changing network conditions while maintaining defined scheduling rules.
2Loss of information
If clients continuously monitor all sectors for beacon transmissions, then neighbor discovery is improved, but power consumption and signaling overhead increase
Solution Approach 1:
The patent enables clients to perform preliminary sector discovery by listening for beacon transmissions at the predefined TBTT of their current sector. The sector information elements carried in these beacons provide clients with advance knowledge of other sectors served by the same AP, including their TBTT values. This preliminary discovery eliminates the need for continuous monitoring of all sectors.
Solution Approach 2:
The system enables clients to self-manage their sector discovery process using the sector information provided in beacons. Clients can autonomously calculate TBTT values for neighboring sectors based on the information received, determine when to switch sectors, and perform handoffs without extensive signaling with the AP. This self-service approach reduces both power consumption and signaling overhead.
3Loss of time
If multiple virtual TBTTs are implemented for different sectors, then inter-sector handoff efficiency is improved, but system complexity and synchronization requirements increase
Solution Approach 1:
The patent extends the TBTT concept from a single scalar value to a multi-dimensional parameter space by introducing sector identifiers and associating each sector with its own TBTT. This dimensional extension allows the system to maintain precise timing synchronization across multiple sectors while providing the flexibility needed for efficient handoffs. The sector dimension is added to the timing structure without fundamentally changing the underlying synchronization mechanism.
Data Source
AI summary
A method for communicating beacon transmissions from a wireless access point (WAP) to a client transceiver in a wireless local area network (WLAN) system (500) includes obtaining a reference timing for the wireless access point (WAP) (502). The sector configuration and the sector timing in the WAP is then determined (503). A virtual target beacon transmission time (TBTT) for the sector of interest serviced by the WAP is then calculated (506), as is a channel number of the sector of interest. Finally, the method provides for listening (507) for a sector beacon signal from the sector of interest at the virtual TBTT and the calculated channel number.