Time-of-Flight Poll Mechanism for Wireless Initiator Dwell Reduction
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Solution Overview
Problem
Current IEEE 802.11 wireless standards require initiators to dwell on a channel for extended periods during time-of-flight (ToF) calculations, preventing them from performing other tasks or switching to different channels, which worsens when trilateration is performed for increased location accuracy.
Innovation Solution
Implementing a ToF poll request mechanism that allows initiators to request ToF results within a defined time period, enabling them to poll responders for previous ToF calculation results without unnecessary dwell time, using a frame exchange sequence that includes a measurement request, acknowledgment, and response with fields for minimum and maximum wait times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the initiator waits for the responder's ToF calculation response, then accurate ToF measurement is achieved, but the initiator must dwell on the requested channel for many milliseconds, preventing other tasks
Solution Approach 1:
The responder performs ToF calculations in advance and stores results before the initiator needs them. The initiator sends a poll request after the dwell period, and the responder retrieves pre-calculated results from memory, eliminating the need for the initiator to wait on the channel.
Solution Approach 2:
A poll request mechanism acts as an intermediary between the initiator and responder. The initiator polls the responder for results instead of waiting directly for calculation completion, allowing the responder to manage calculation timing independently while providing results when requested.
2Measurement precision
If the initiator performs trilateration for increased location accuracy, then location precision is improved, but the total dwell time is multiplied by the number of ToF calculations required
Solution Approach 1:
Multiple ToF calculations are performed in advance by the responder before the initiator begins its trilateration process. Results from multiple responders are stored and made available through polling, allowing the initiator to perform accurate trilateration without extended dwell periods on each channel.
3Reliability
If the initiator dwells on the ToF channel until response is received, then complete ToF exchange is achieved, but the initiator cannot return to serving channel or perform power save functions
Solution Approach 1:
The responder completes ToF calculations and stores results before the initiator finishes its channel operations. The initiator can switch channels or enter power save mode after sending the initial request, then retrieve results via polling without compromising the completeness of the ToF exchange.
Solution Approach 2:
The poll request mechanism mediates between the initiator's need to switch channels and the responder's need to provide complete ToF results. The initiator can leave the channel freely and return later to poll for results, while the responder ensures complete calculations are available when requested.
Data Source
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AI summary
Embodiments of a communication station and method for time-of-fiight (ToF) location determination in a wireless network are generally described herein. In some embodiments, a responding communication station receives a ToF measurement request. The responding communication station transmits an acknowledgment of the ToF measurement request. The responding communication station also transmits a response to the ToF measurement request that includes an indication of a time period for an initiating communication station to poll the responding communication station for a ToF result.