Sidelink Backscatter Positioning for Indoor Asset Tracking
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Solution Overview
Problem
Existing wireless positioning systems, such as GPS, face challenges in urban and indoor environments due to signal blockages and multipath propagation, leading to low accuracy and inefficiency, while existing backscatter communication systems lack effective methods for precise asset tracking.
Innovation Solution
A method utilizing sidelink communications between user devices to assign and manage backscatter frequency offsets for backscatter nodes, enabling them to reflect positioning signals, allowing channel estimate information to be collected and used for accurate positioning through trilateration or multilateration, even in areas with limited base station coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If backscatter nodes are used for positioning, then energy efficiency is improved, but positioning accuracy deteriorates due to signal blockages and multipath propagation
Solution Approach 1:
The patent divides the positioning system into multiple components: backscatter nodes for passive reflection, user devices for active signal transmission and reception, and network nodes for coordination. This segmentation allows each component to perform its specific function optimally while collectively achieving both energy efficiency and positioning accuracy through coordinated operation.
Solution Approach 2:
The patent introduces user devices as intermediary elements that actively transmit positioning signals and receive backscattered signals from backscatter nodes. These user devices serve as mediators between the backscatter nodes and network nodes, enabling accurate positioning measurements while allowing backscatter nodes to remain passive and energy-efficient.
2Loss of energy
If existing backscatter communication systems are used, then energy consumption is reduced, but asset tracking capability deteriorates due to lack of effective positioning methods
Solution Approach 1:
The patent makes the backscatter communication system universal by enabling it to perform both its original backscatter communication function and the additional function of positioning. The backscatter nodes continue to operate in their energy-efficient backscatter mode while the system integrates positioning capabilities through user devices transmitting signals and network nodes coordinating the positioning procedure, thus achieving multi-functionality without compromising energy efficiency.
Solution Approach 2:
The patent implements preliminary actions by having user devices transmit positioning signals before the backscatter nodes reflect them. The network node also performs preliminary configuration by assigning frequency offsets to backscatter nodes and providing positioning signal configuration information. These preliminary actions enable the backscatter nodes to accurately reflect signals for positioning purposes while maintaining their energy-efficient operation.
3Area of stationary object
If base station coverage is limited, then network coverage is reduced, but positioning capability deteriorates due to lack of available signals
Solution Approach 1:
The patent transitions from traditional downlink positioning (network to user) to uplink positioning (user to network) by having user devices transmit positioning signals. This dimensional change in signal transmission direction enables positioning capability even in areas with limited base station coverage, as user devices can actively transmit signals that backscatter nodes reflect, providing positioning information without requiring extensive network infrastructure.
Data Source
AI summary
A method includes determining backscatter frequency offsets assigned to backscatter nodes to be positioned; controlling transmitting, by the first user device, a positioning signal using time-frequency resources found unused by the first user device or allocated by a network node; controlling receiving, by the first user device via sidelink communication, channel estimate information from a plurality of second user devices, wherein a channel estimate information indicates an estimate of a channel between one of the plurality of second user devices and each of the at least some of the backscatter nodes, and wherein the channel estimate information received from each second user device is based on the transmitted positioning signal that is frequency shifted by an assigned backscatter frequency offset and reflected by each of the at least some of the backscatter nodes; and controlling transmitting, by the first user device to the network node, the received channel estimate information.