Abstract
This paper considers the complex-valued mixing matrix estimation and direction-of-arrival (DOA) estimation of synchronous orthogonal frequency hopping (FH) signals in the underdetermined blind source separation (UBSS). A novel mixing matrix estimation algorithm is proposed by detecting single source points (SSPs) where only one source contributes its power. Firstly, the proposed algorithm distinguishes the SSPs by the comparison of the normalized coefficients of time frequency (TF) points, which is more effective than existing detection algorithms. Then, mixing matrix of FH signals can be estimated by the hierarchical clustering method. To sort synchronous orthogonal FH signals, a modified subspace projection method is presented to obtain the DOAs of FH. One superiority of this paper is that the estimation accuracy of the mixing matrix can be significantly improved by the proposed SSPs detection criteria. Another superiority of this paper is that synchronous orthogonal FH signals can be sorted in underdetermined condition. The experimental results demonstrate the efficiency of the two proposed algorithms.
Highlights
Frequency hopping (FH) signals have been widely used in wireless communications and radar systems due to their low probability of detection and interception [1,2,3,4,5]
This paper proposes a novel method to detect single source points (SSPs) in time frequency (TF) domain and an improved subspace projection method is proposed to recover signals
The synchronous FH sorting problem is solved in underdetermined blind source separation (UBSS) situation
Summary
Frequency hopping (FH) signals have been widely used in wireless communications and radar systems due to their low probability of detection and interception [1,2,3,4,5]. Many single source point (SSP) detection methods have been proposed to improve the accuracy of mixing matrix estimation. A time frequency ratio of mixtures (TFROM) method was proposed in [27] by calculating the ratio values to estimate mixing matrix at each TF point. This method requires that only one source is active at TF points so that the imaginary parts of the STFT coefficients are equal to zero. A new criterion is proposed to identify SSPs to improve mixing matrix estimation performance Another improved source recovery method is introduced to estimate frequencies according to subspace projection.
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