In actual urban scenes, the uncanonical facilities complicate the EM wave propagation environment, which makes traditional methods hard to work. To solve this problem, a novel method for Localization based on ray tracing is established. Firstly, the ray tracing technique is introduced to calculate the theoretical propagation path from the target, by which a dictionary of predicted multipath signals relative to different position parameters is constructed. Consequently, the position of the target can be estimated via matching Euclidean distance between the received multipath echoes and the predicted multipath dictionary. The simulation experiments show that the proposed method has higher localization accuracy especially in complicated scene.
Multipath exploitation radar (MER) integrates the prior environment to make use of the extra target information encoded in multipath signals, which is capable of localization for single target with a wide-beam antenna. Nevertheless, as the number of targets in the urban scene increases, the association between the target and its corresponding multipath’s time-of- arrival (ToA) faces the problem of combination explosion. Moreover, accounting for the measurement and extraction error attached with the ToAs, there may be multiple combinations with similar probability, which leads to a significant accuracy decline or even wrong location results. To solve the problem, this paper proposes a novel algorithm that jointly uses MER and time-frequency (TF) features for multi-target localization especially for pedestrians. Through the TF analysis of the micro-Doppler feature, the pedestrian characteristics such as pace and phase of periodic action can be obtained. Based on these characteristics, the multipath’s ToAs in multi-target scenario can be associated with each different target, hence the aforementioned multi-target location problem can be transferred to a series of single-target localization problems. The impacts of target number on localization accuracy are analyzed in detail. The effectiveness of the proposed method is validated through the simulation experiments. The results indicate that, compared with the traditional methods, the proposed method has higher localization accuracy in multi-target scene.
KEYWORDS: Radar, Doppler effect, Error analysis, Signal detection, Signal processing, Target detection, Radar signal processing, Data processing, Wave propagation, Sun
Multi-target localization in a multipath environment is a complex problem. The localization accuracy of the existing Time of Arrival (ToA)-based monostatic radar localization method is low under the condition of multi targets and a high error level. A multi-target localization method based on joint utilization of ToA and Doppler via monostatic radar is proposed in this paper to solve this problem. The proposed method can improve the localization accuracy effectively under the premise of known ToA and Doppler frequency. Initially, the proposed method analyzes the relationship between the Doppler frequency of multipath returns and the actual velocity of the target. Then the ToA-based localization method can obtain the initial estimation position of each target, and the direction of velocity corresponding to Doppler frequency is obtained according to the initial estimation position. Based on the principle of velocity vector synthesis, we can obtain the estimation velocity of each target. Finally, the invalid position in the initially estimated place is detected by using the velocity consistency theorem. Simulation results show that the proposed method can eliminate the invalid estimation position and improve localization accuracy in a high error level and multiple targets.
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