Passive Positioning via Sector Sweep TOA in 60 GHz Networks
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Solution Overview
Problem
Current wireless communication systems, particularly in the 60 GHz band, face challenges with high atmospheric attenuation and directional transmissions, making passive positioning difficult due to the directed nature of communications, which hampers the ability to measure Time of Arrival (TOA) of signals effectively in 802.11ad networks.
Innovation Solution
The system employs sector sweep procedures to obtain frames from multiple wireless nodes, estimating position based on Time of Arrival (TOA) measurements during sector sweeps, using double difference calculations to compensate for clock drifts and determine precise positioning without active association with access points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional transmissions are used in 60 GHz band, then communication reliability is improved through beamforming, but positioning capability deteriorates due to inability to measure TOA effectively
Solution Approach 1:
The patent performs sector sweep procedures in advance to establish beamforming relationships and transmit reference frames before actual positioning is needed. By pre-establishing the directional transmission characteristics and timing information during sector sweeps, the system enables subsequent passive positioning without requiring active TOA measurements during the actual positioning event, thus resolving the contradiction between directional transmission reliability and positioning capability.
Solution Approach 2:
The patent introduces third wireless nodes (access points or stations with known positions) as intermediaries to facilitate positioning. Instead of requiring direct TOA measurements between the mobile device and transmitting nodes, the system uses timing information exchanged through these intermediary nodes during sector sweeps to indirectly determine position, overcoming the limitation of directional transmissions blocking direct TOA measurement paths.
2Loss of energy
If passive positioning is implemented without active association, then network resource consumption is reduced, but positioning accuracy deteriorates due to lack of synchronized timing
Solution Approach 1:
The patent enables wireless nodes to perform positioning functions autonomously using timing information already exchanged during normal sector sweep operations. The mobile device uses timing data from reference frames received during sector sweeps to calculate its own position without requiring active positioning requests or synchronized timing protocols, thus achieving passive positioning with minimal network resource consumption while maintaining acceptable accuracy through the self-service mechanism.
Data Source
AI summary
Certain aspects of the present disclosure generally relate to passive positioning based on directional transmissions, such as directional beacons transmitted during a sector sweep procedure.