Wireless Positioning via Reference Device Scheduling
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Solution Overview
Problem
Existing wireless network positioning techniques, such as double differencing, face challenges including clock errors between stations and reference stations, channel differences, and reduced accuracy when multiple stations attempt to determine their locations simultaneously.
Innovation Solution
A method where a reference device compiles a schedule specifying measurement times for multiple wireless channels and provides it to stations, allowing them to tune to specific channels to receive messages with time-of-departure and time-of-arrival timestamps, enabling accurate position determination without requiring synchronized clocks across access points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple stations determine their positions simultaneously using double differencing, then positioning functionality is provided to multiple stations, but clock errors between stations and reference stations affect positioning accuracy
Solution Approach 1:
A reference device is introduced as an intermediary between access points and stations. The reference device receives positioning messages from access points, determines precise time-of-arrival timestamps, and provides both the timestamps and access point locations to stations. This intermediary eliminates the need for stations to directly measure timestamps from access points, thereby removing clock error impacts on positioning accuracy while enabling multiple stations to determine positions simultaneously.
2Adaptability or versatility
If stations use different wireless channels for communication, then channel diversity is utilized, but delay in exchange of time-of-arrival timestamps between reference station and station reduces accuracy or results in useless location measurement
Solution Approach 1:
The reference device performs preliminary actions by receiving positioning messages from access points before stations need to use them. The reference device determines time-of-arrival timestamps and stores access point location information in advance. When stations request positioning data, the reference device immediately provides pre-processed timestamp and location information, eliminating delays in timestamp exchange and ensuring accurate location measurements even when stations use different wireless channels.
3Productivity
If a large number of stations attempt to determine their locations simultaneously, then network utilization is increased, but overhead increases and may reduce efficiency
Solution Approach 1:
The reference device merges the functions of multiple access points by centralizing the reception of positioning messages and the determination of time-of-arrival timestamps. Instead of each access point independently managing timestamp generation and distribution, the reference device consolidates these functions. This merging reduces system overhead by eliminating redundant timestamp exchange processes between multiple access points and numerous stations, while still enabling a large number of stations to determine their positions simultaneously through the single reference device.
Data Source
AI summary
A station (STA) receives a schedule from a reference device in a wireless network. The schedule provides a measurement time for each of one or more wireless channels. The STA tunes to a first channel of the one or more wireless channels in accordance with the schedule. While tuned to the first channel in accordance with the schedule, the STA receives a first message from a first access point (AP). The first message, which includes a time-of-departure timestamp from the reference device, is time-stamped with a time-of-arrival timestamp. The STA receives an indication of a time at which the reference device received the first message from the first AP. The STA determines its position based in part on the time-of-departure timestamp, the time-of-arrival timestamp, and the time at which the reference device received the first message.