Abstract
This paper introduces a novel algorithm to excise single and multicomponent chirp-like interferences in direct sequence spread spectrum (DSSS) communications. The excision algorithm consists of two stages: adaptive signal decomposition stage and directional element detection stage based on the Hough-Radon transform (HRT). Initially, the received spread spectrum signal is decomposed into its time-frequency (TF) functions using an adaptive signal decomposition algorithm, and the resulting TF functions are mapped onto the TF plane. We then use a line detection algorithm based on the HRT that operates on the image of the TF plane and detects energy varying directional elements that satisfy a parametric constraint. Interference is modeled by reconstructing the corresponding TF functions detected by the HRT, and subtracted from the received signal. The proposed technique has two main advantages: (i) it localizes the interferences on the TF plane with no cross-terms, thus facilitating simple filtering techniques based on thresholding of the TF functions, and is an efficient way to excise the interference; (ii) it can be used for the detection of any directional interferences that can be parameterized. Simulation results with synthetic models have shown successful performance with linear and quadratic chirp interferences for single and multicomponent interference cases. The proposed method excises the interference even under very low SNR conditions of dB, and the technique could be easily extended to any interferences that could be represented by a parametric equation in the TF plane.
Highlights
In spread spectrum (SS) communications, the message signal is modulated and spread over a wider bandwidth with a pseudonoise (PN) code known at the receiver, and transmitted over the channel
They perform the excision of limited type of interferences such as linear or sinusoidal interferences [9, 12]. Considering these two disadvantages, we propose a new excision method based on constructing a positive TF distributions (TFDs) of the received SS signal using an adaptive signal decomposition technique, the matching pursuit (MP) algorithm [20]; followed by a line detection algorithm based on the Hough-Radon transform (HRT)
We proposed a new interference excision algorithm and evaluated its performance in terms of the BER and chip error rates
Summary
In spread spectrum (SS) communications, the message signal is modulated and spread over a wider bandwidth with a pseudonoise (PN) code known at the receiver, and transmitted over the channel. Earlier interference excision methods based on TFDs suffer from a tradeoff between the TF resolution and the TFD cross-terms [17,18,19] They perform the excision of limited type of interferences such as linear or sinusoidal interferences [9, 12]. Considering these two disadvantages, we propose a new excision method based on constructing a positive TFD of the received SS signal using an adaptive signal decomposition technique, the matching pursuit (MP) algorithm [20]; followed by a line detection algorithm based on the HRT.
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