Enhanced Fine Timing Measurement Ranging in WLAN
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Solution Overview
Problem
Current wireless local area network (WLAN) technologies face challenges in accurately determining the distance between devices within a limited area using existing range measurement methods, which are inefficient and lack precise timing measurements.
Innovation Solution
The implementation of an enhanced fine timing measurement (EFTM) based range measurement method using extended control frame formats within a transmission opportunity (TXOP), where devices exchange null data packets to calculate round trip time, allowing for precise distance determination between devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing range measurement methods are used in WLAN, then devices can determine distance within a limited area, but the measurement precision is insufficient and timing accuracy is poor
Solution Approach 1:
The system performs preliminary actions by establishing a TXOP (Transmission Opportunity) framework before conducting range measurements. The initiating device secures transmission rights and prepares the measurement environment in advance, allowing for controlled and accurate timing measurements without interference from other transmissions.
Solution Approach 2:
The patent replaces traditional mechanical timing methods with enhanced fine timing measurement (EFTM) mechanisms that use precise timestamp recording and processing. The system substitutes coarse timing with fine-grained timing measurement using departure and arrival time stamps of null data packets, achieving sub-microsecond accuracy.
2Measurement precision
If enhanced fine timing measurement is implemented within TXOP, then round trip time can be determined with high accuracy, but the device complexity increases due to extended control frame formats and additional processing requirements
Solution Approach 1:
The extended control frame format is segmented into distinct functional fields: dialog token for measurement identification, bandwidth indicator for resource allocation, ENDP type indicator for packet type specification, feedback type indicator for measurement feedback mode, and channel state parameters for radio conditions. This segmentation allows each component to perform its specific function independently, managing complexity through modular design.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of null data packets (NDP) that carry timing information without actual data payload. These NDPs serve as intermediaries between the initiating and responding devices, enabling precise timing measurement while keeping the measurement traffic separate from regular data traffic, thus simplifying the overall system operation.
3Measurement precision
If null data packets are exchanged for timing measurement, then precise departure and arrival times can be recorded, but the quantity of communication overhead increases
Solution Approach 1:
The system applies partial action by using null data packets that contain only the essential timing measurement information without full data payloads. The NDPs include just the necessary control fields and timing stamps, performing the measurement function with minimal data transmission, thus reducing overall communication overhead while maintaining measurement precision.
Data Source
AI summary
Aspects of the disclosure provide an apparatus that includes a transceiver circuit and a processing circuit. The transceiver circuit is configured to transmit and receive wireless signals. The processing circuit is configured to generate a request frame using an extended control frame format to indicate an enhanced fine timing measurement (EFTM) based range measurement to a second apparatus, cause the transceiver circuit to transmit, when a transmission opportunity (TXOP) is granted to the apparatus, wireless signals carrying the request frame to start the EFTM based range measurement that exchanges null data packets with the second apparatus, and determine a round trip time based on departure and arrival timing information of the null data packets.