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| Clustering Based Blind Despread Method of Tamed Direct Sequence Spread Spectrum Signals |
| Wang Hang; Guo Jing-bo; Wang Zan-ji |
| Department of Electrical Engineering, Tsinghua University, Beijing 100084, China |
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Abstract Blind despread of multi-sequence Direct Sequence Spread Spectrum signals (tamed DSSS signals) with unknown spreading codes are discussed in this paper. The Dominant Mode DeSpreading (DMDS) algorithm is certified to be a successful solution for the blind estimation of the conventional DSSS signals. However, it proved to be not applicable to tamed DSSS signals. Borrowing unsupervised cluster analysis ideas, a novel method named K-means Clustering DeSpreading (KCDS) algorithm for tamed DSSS signals is proposed. KCDS algorithm, divides the tamed DSSS signal into non-overlapped individuals, and then exploits the clustering property of these individuals to estimate the spreading codes. The delay time and the number of spreading codes can be estimated by maximizing the average silhouette width. It is demonstrated to be effective via simulation results for a 32-ary DSSS signal in the presence of zero-mean noise.
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Received: 30 July 2007
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2009, Vol. 31 
