Ding-Jie Xu

Bio: Ding-Jie Xu is an academic researcher from Harbin Engineering University. The author has contributed to research in topics: Spread spectrum & Multipath propagation. The author has an hindex of 1, co-authored 3 publications receiving 6 citations.

Narrowband Interference Suppression Using RKF-Based Recurrent Neural Network in Spread Spectrum System

Abstract: A new adaptive neural network predictor to eradicate the narrowband interference in the spread spectrum system is proposed in this paper. The effectively robust Kalman filter (RKF) algorithm is adopted to adjust the synaptic weights in the nonlinear recurrent architecture and thereby estimate the narrowband interference. The main characteristics of the proposed RKF-based canceller are its rapid convergence rate and precise prediction. Simulation results reveal that the RNNP based on RKF algorithm has large improvement on the interference suppression capability compared with conventional LMS, ACM and RTRL-based canceller in CWI and ARI environments, respectively.

Study on Carrier Tracking Performance of DS/BPSK Navigation Receiver in the Multipath Environment

Abstract: The carrier phase tracking performance in the presence of multipath component is researched in the paper for the DS/BPSK navigation receiver. The pseudonoise (PN) code tracking loop of the receiver adopts the noncoherent delay lock loop (DLL), and the influence of multipath on the carrier phase tracking error is analyzed. The hardware implementation of the signal carrier tracking scheme is provided, and the mathematics mode of the carrier phase tracking loop is presented. The relation of multipath code delay and multipath carrier phase delay is analyzed. Based on the analyses of carrier phase tracking model in multipath propagating environments, the paper gives some simulations of the carrier tracking loop performance, and builds up the carrier tracking loop though the Simulink of Matlab.

The Application of an Improved Hybrid Interference Cancellation Method in the Radio Navigation System

Abstract: Against eliminating the multiple access interference (MAI) and sky-wave interference under multi-path channel in the radio navigation system, an improved hybrid interference cancellation (HIC) method that combines the advantages of both the successive interference canceller (SIC) and the parallel interference canceller (PIC) is proposed in this paper. It has the advantages of low complexity and easy hardware realization. The model structure is presented and the expression of bit error rate (BER) is derived analytically, the simulation results show that the method is obviously better than the traditional receivers in the presence of the estimation error (includes the timing and phase estimation errors), especially when the estimation errors are small, the probability of BER in the second stage of the improved HIC is two orders of magnitude higher than traditional receiver. The experiment verification results show that the improved HIC can improve the signal-to-noise (SNR) of the weak signal effectively and have a good performance to eliminate the MAI and the sky-wave interference, thus the improved HIC technique we proposed has high practical application value.

Multipath error analysis of carrier Tracking Loop in GPS receiver

Abstract: The error of Code Tracking Loop(CTL) of GPS receiver influences the error of carrier tracking loop in the presence of multipath. The error models of carrier tracking loop are established in the multipath environment when the non-coherent Early Minus Late(EML) power mode CTL and the non-coherent Dot-product(DOT) power mode CTL are used. The impacts of multipath parameters and correlator spacing on the error of carrier tracking loop are analyzed by simulation. The simulation results show that the two non-coherent CTLs have little difference in affecting the carrier tracking error. Furthermore, the narrow correlator technology cannot reduce the error of carrier tracking loop.

Carrier Phase-Based Synchronization and High-Accuracy Positioning in 5G New Radio Cellular Networks

Abstract: Inspired by excellent precision of carrier phase positioning, this paper presents a new carrier phase positioning technique for 5G new radio cellular networks with a focus on clock synchronization and integer ambiguity resolution. A carrier-phase based clock offset estimation method is first proposed to achieve precise clock synchronization among base stations, and proved to achieve the Cramér–Rao Lower Bound (CRLB) asymptotically. A fusion method is developed to fuse the estimated positions of a mobile station (MS) based on time-difference-of-arrival, with the estimated position changes based on the temporal changes of carrier phase measurements. While circumventing the integer ambiguities of the carrier phase measurements, the fusion method provides quality interim estimates of the MS positions, at which the measurements can be linearized to resolve the integer ambiguities. As a result, precise MS positions can be obtained based on the disambiguated carrier phase measurements. Numerical simulations show that the proposed carrier phase positioning can achieve a centimeter-level accuracy in wireless cellular networks.

Iterative Narrowband Interference Suppression for DS-CDMA Systems Using Feed-Forward Neural Network

Abstract: This paper proposes a feed-forward neural network predictor to adaptively estimate and suppress the narrowband interference (NBI) in the Direct Sequence-Code Division Multiple Access (DS-CDMA) signal. The iterative code-aided estimation is used to further improve the system performance. Simulation results reveal that the proposed algorithm outperforms conventional linear prediction filtering and recurrent neural networks (RNN) based NBI rejection methods, in different interference models.

A Comprehensive Survey on GNSS Interferences and the Application of Neural Networks for Anti-jamming

Abstract: In recent years, modern systems are highly reliant on Global Navigation Satellite Systems (GNSS) as reliable positioning, navigation, and timing services have become crucial in many safety-critical...