Uplink OFDMA Trigger Frame for Indoor Location Tracking Overhead
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Solution Overview
Problem
Current location tracking systems in indoor environments face significant signaling overhead due to the need for multiple antenna configurations and frequent block acknowledgement processes, leading to high airtime usage and inefficiencies in determining the location of client devices.
Innovation Solution
Implementing orthogonal frequency division multiple access (OFDMA) transmissions for implicit channel sounding, where a trigger frame is used to elicit an uplink OFDMA response from client devices, reducing the number of frame exchanges and airtime usage, and allowing AP devices to determine location-related measurements based on received signal strength indicator (RSSI) and angle of arrival (AoA) information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If block acknowledgement processes are performed for implicitly sounding each antenna configuration, then location determination capability is improved, but signaling overhead increases
Solution Approach 1:
The patent combines multiple antenna configurations into a single MIMO channel sounding process. Instead of performing separate block acknowledgement processes for each antenna configuration, the system uses a unified OFDMA-based sounding mechanism that simultaneously captures channel state information across multiple antennas, thereby reducing signaling overhead while maintaining location determination capability.
Solution Approach 2:
The trigger frame and uplink OFDMA transmission mechanism serves multiple functions simultaneously: it performs channel sounding for multiple antenna configurations, enables location determination through RSSI and AoA measurements, and maintains data transmission functionality. This multi-functional approach eliminates the need for separate dedicated sounding procedures for each antenna.
2Measurement precision
If multiple antenna configurations are used for location tracking, then location accuracy is improved, but airtime usage increases
Solution Approach 1:
The patent implements periodic channel sounding using trigger frames that are transmitted at scheduled intervals rather than continuously. This periodic approach allows the system to maintain accurate location tracking through regular RSSI and AoA measurements while significantly reducing airtime consumption compared to continuous multi-antenna probing.
Solution Approach 2:
Multiple antenna measurements are merged into a single uplink OFDMA transmission event. The trigger frame initiates a unified sounding process that collects channel state information from all antenna configurations simultaneously in one airtime slot, rather than requiring separate measurement slots for each antenna.
3Measurement precision
If implicit channel sounding is performed for each antenna configuration, then channel state information quality is improved, but frame exchange quantity increases
Solution Approach 1:
The uplink OFDMA transmission serves as a universal sounding mechanism that simultaneously provides channel state information for multiple antenna configurations. A single trigger frame and corresponding uplink transmission replace what would otherwise require multiple separate frame exchanges for each antenna, maintaining comprehensive CSI quality while reducing the total number of frames exchanged.
Solution Approach 2:
The patent segments the channel sounding process into two efficient components: a downlink trigger frame that coordinates the sounding, and an uplink OFDMA transmission that carries the channel responses from multiple antennas simultaneously. This segmented approach consolidates multiple frame exchanges into a streamlined two-step process.
Data Source
AI summary
In one embodiment, a method is performed. An access point (AP) device may communicate signaling relating to a client device allocation for a location-related measurement. The AP device may transmit a trigger frame. The AP device may receive a response to the trigger frame from a client device. The response may include an uplink orthogonal frequency division multiple access (OFDMA) transmission. A location-related measurement of the client device may be determined based on the response to the trigger frame.