Wireless Device Speed Estimation from Multipath Doppler Signals
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Solution Overview
Problem
Existing methods for estimating vehicle speed, such as Doppler radars and satellite navigation systems, are costly, provide localized coverage, and lack sufficient frequency for accurate speed estimation, while network-based positioning techniques only offer average speeds between distant positions.
Innovation Solution
A method using existing wireless communications network signaling, such as 4G and 5G, to estimate traveling speed by analyzing Doppler speed differences and direction of departure of multipath components from signal sequences transmitted via multiple paths, utilizing existing hardware for ubiquitous coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Doppler radars are deployed to measure vehicle speed, then speed measurement accuracy is improved, but deployment cost and infrastructure complexity increase
Solution Approach 1:
The wireless device itself transmits the signal sequence that carries Doppler information, eliminating the need for external radar infrastructure. The device's own transmission serves the dual purpose of communication and speed measurement, with the network node extracting speed information from the received signal's multipath components.
Solution Approach 2:
The wireless communication signal serves multiple functions simultaneously: it enables both data communication and speed estimation. The same signal sequence used for normal wireless communication also provides Doppler information for speed measurement, eliminating the need for separate dedicated speed measurement infrastructure.
2Measurement precision
If Doppler radars are deployed along roads to measure speed, then speed estimation capability is improved, but coverage area is limited to specific locations
Solution Approach 1:
The method enables speed estimation to be performed anywhere within the wireless network coverage area, as the network nodes throughout the coverage zone can serve as measurement points. This transforms the coverage from localized radar spots to ubiquitous network-wide coverage.
Solution Approach 2:
The wireless communication network acts as an intermediary infrastructure that provides speed estimation capability across its entire coverage area. Instead of deploying separate measurement infrastructure, the existing network nodes serve as intermediaries for both communication and speed measurement functions.
3Measurement precision
If satellite navigation systems are used to determine vehicle speed, then positioning capability is improved, but speed measurement frequency and accuracy are insufficient
Solution Approach 1:
The wireless device transmits signal sequences periodically as part of normal communication, enabling continuous and frequent speed measurements. This periodic transmission provides speed estimation at much higher frequencies than satellite navigation systems, allowing for accurate real-time speed tracking.
4Area of stationary object
If network-based positioning techniques are used to estimate speed, then positioning coverage is improved, but speed accuracy deteriorates due to average speed calculation between distant positions
Solution Approach 1:
The signal received by the network node is segmented into multiple multipath components, each representing a different propagation path. By analyzing the Doppler information of individual multipath components rather than relying on position changes between distant points, the system achieves accurate speed measurement while maintaining wide coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and cost-effective speed estimation of wireless devices, including vehicles, without the need for additional infrastructure, providing comprehensive coverage.
Implementation Method 1
The Doppler radar receives the reflected signal and analyzes how the motion of the target has shifted the frequency of the received signal. The frequency shift is proportional to a radial component of the speed of the target relative to the Doppler radar.
Data Source
AI summary
A computer-implemented method for estimating a travelling speed of a wireless device in a wireless communications network, where the wireless device has transmitted a signal sequence to a network node via two or more signal paths. The method includes obtaining data indicative of a Doppler speed difference between respective multipath components of the signal sequence transmitted via the two or more signal paths; obtaining data indicative of direction of departure, DoD, (nUE,P1, nUE,P2) of the two or more signal paths at the wireless device; and estimating the travelling speed of the wireless device based on the data indicative of the Doppler speed difference and the data indicative of DoD.