OFDMA Simultaneous RTT Measurement for WLAN Location Latency
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Solution Overview
Problem
Existing methods for determining the location of stations in a WLAN are inefficient, requiring multiple round trip time (RTT) measurements and increasing latency due to the need for multiple device interactions for triangulation.
Innovation Solution
The method involves transmitting simultaneous fine timing measurement frames to multiple stations using orthogonal frequency-division multiple access (OFDMA) procedures, allowing for simultaneous receipt and processing of measurement frames to reduce latency and enable near real-time location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate RTT measurements are performed for each station to determine location, then measurement precision is improved, but loss of time increases due to sequential measurements and multiple device interactions
Solution Approach 1:
The patent combines multiple separate RTT measurement procedures into a single unified measurement process. The initiating station sends a single measurement request message that triggers simultaneous measurement frame transmissions from multiple responding stations using OFDMA. This merging of multiple sequential measurements into one parallel measurement process reduces the time required for location determination while maintaining the precision needed for accurate triangulation.
Solution Approach 2:
The patent introduces a new dimension to the measurement process by utilizing OFDMA technology, which allows multiple stations to transmit measurement frames simultaneously on different resource units (subcarriers, time slots, or spatial streams). This dimensional expansion from sequential single-channel measurements to parallel multi-channel measurements enables simultaneous RTT measurements across multiple stations, dramatically reducing measurement time while preserving accuracy.
2Device complexity
If traditional sequential RTT measurement procedures are used, then device complexity is minimized, but productivity decreases due to repeated device interactions and sequential processing
Solution Approach 1:
The patent creates a universal measurement framework where a single measurement request message can initiate RTT measurements with multiple responding stations simultaneously. The initiating station's single request serves multiple purposes: it triggers measurement frames from all responding stations, coordinates the simultaneous transmissions, and enables parallel processing. This multi-functional approach increases productivity by eliminating repeated device interactions while managing complexity through standardized procedures.
Solution Approach 2:
The patent employs preliminary action by having the initiating station send a single measurement request message that pre-coordinates all subsequent measurement activities. This preliminary request contains all necessary information for responding stations to transmit their measurement frames simultaneously at the correct time. By performing this coordination action in advance, the system enables efficient parallel measurements without requiring complex real-time arbitration, thus improving productivity while keeping device complexity manageable.
Data Source
AI summary
Techniques are provided for obtaining round trip timing (RTT) measurements using orthogonal frequency-division multiple access procedures. An example method for determining distances to a plurality of stations includes receiving a respective first measurement frame from each of the plurality of stations, wherein the first measurement frame from each of the plurality of stations is transmitted simultaneously, transmitting a single multi-station block acknowledgment frame to the plurality of stations, receiving a respective second measurement frame from each of the plurality of stations, wherein the second measurement frame from each of the plurality of stations is transmitted simultaneously, and determining a respective distance to each of the plurality of stations based at least in part on the first measurement frame and the second measurement frame from at least some of the plurality of stations.