Abstract

In the coexistence of multiple types of interfering signals, the performance of interference suppression methods based on time and frequency domains is degraded seriously, and the technique using an antenna array requires a large enough size and huge hardware costs. To combat multi-type interferences better for GNSS receivers, this paper proposes a cascaded multi-type interferences mitigation method combining improved double chain quantum genetic matching pursuit (DCQGMP)-based sparse decomposition and an MPDR beamformer. The key idea behind the proposed method is that the multiple types of interfering signals can be excised by taking advantage of their sparse features in different domains. In the first stage, the single-tone (multi-tone) and linear chirp interfering signals are canceled by sparse decomposition according to their sparsity in the over-complete dictionary. In order to improve the timeliness of matching pursuit (MP)-based sparse decomposition, a DCQGMP is introduced by combining an improved double chain quantum genetic algorithm (DCQGA) and the MP algorithm, and the DCQGMP algorithm is extended to handle the multi-channel signals according to the correlation among the signals in different channels. In the second stage, the minimum power distortionless response (MPDR) beamformer is utilized to nullify the residuary interferences (e.g., wideband Gaussian noise interferences). Several simulation results show that the proposed method can not only improve the interference mitigation degree of freedom (DoF) of the array antenna, but also effectively deal with the interference arriving from the same direction with the GNSS signal, which can be sparse represented in the over-complete dictionary. Moreover, it does not bring serious distortions into the navigation signal.

Highlights

  • The global navigation satellite system (GNSS) plays an increasingly important role in military and civil areas; the risk caused by the vulnerability of GNSS signals is getting more and more serious

  • In terms of the characteristics of the GNSS, one way of enhancing its ability of mitigating radio frequency interferences is to improve the design of navigation satellites [1], for example optimizing the structure of signals and increasing the power of transmitters; but, these methods are too costly in terms of the design cycle and material resources

  • Focusing on the complex electromagnetic environment in which multiple types of interfering signals coexist at the same time, a novel cascaded multi-type interferences mitigation method using sparse decomposition and array processing is introduced and examined in this paper

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Summary

Introduction

The global navigation satellite system (GNSS) plays an increasingly important role in military and civil areas; the risk caused by the vulnerability of GNSS signals is getting more and more serious. By combining time and spatial processing, it is possible to increase the number of suppressed narrowband interfering signals without extra elements in the array Their superior advantages are obvious and desirable, the STAP may introduce cross-correlation function biases and distortions, which can result in inferior position estimates [11,12,13]. Existing interference mitigation methods are able to improve the performance of GNSS receivers in the presence of interferences, there are enormous challenges when they suppress multiple types of interferences: (1) the hardware or space costs are enormous; (2) when the DOA of the interference (especially for the wideband interference) is close to the GNSS signal, their performance degrades seriously; (3) the methods using both spatial and time-/frequency-domain processing may distort the GNSS signals. Several simulation scenarios are considered to show the effectiveness of the proposed method for multi-type interferences mitigation, and the compared methods are the well-known MPDR beamformer [10] and the distortionless space-time processor [16]

Signal Model
The Proposed Method
Matching Pursuit Decomposition
Analysis of Interference Detection Performance
The Mutual Influence of Multiple Signals
The Improved MP Algorithm and Design Strategy of the Over-Complete Dictionary
The Terminate Condition of MP
The Improved Double Chain Quantum Genetic Algorithm
MPDR Beamformer
Performance of the Improved DCQGA
Performance of the Proposed Interference Mitigation Method
Influence of the DCQGMP-Based Interference Suppression on the GNSS Signal
Performance of the Cascade Method for Multi-Type Interferences Mitigation
Conclusions
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