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Circulant matrix representation of PN-sequences with ideal autocorrelation property
, Article IWCIT 2015 - Iran Workshop on Communication and Information Theory, 6 May 2015 through 7 May 2015 ; May , 2015 ; 9781479982356 (ISBN) ; Shoreh, M. H ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, we investigate PN-sequences with ideal autocorrelation property and the consequences of this property on the number of +1s and -1s and run structure of sequences. We begin by discussing and surveying about the length of PN-sequences with ideal autocorrelation property. From our discussion and survey we introduce circulant matrix representation of PN-sequence. Through circulant matrix representation we obtain system of non-linear equations that lead to ideal autocorrelation property. Rewriting PN-sequence and its autocorrelation property in {0,1} leads to a definition based on Hamming weight and Hamming distance and hence we can easily prove some results on the PN-sequences...
An internally coded partial-band DS-CDMA system and its performance analysis
, Article ICU 2005: 2005 IEEE International Conference on Ultra-Wideband, Zurich, 5 September 2005 through 8 September 2005 ; Volume 2005 , 2005 , Pages 38-42 ; 078039397X (ISBN); 9780780393974 (ISBN) ; Nasiri Kenari, M ; Shayesteh, M. G ; Sharif University of Technology
2005
Abstract
We propose a new partial-band DS-CDMA scheme for UWB communication systems, which is based on frequency-hopping (FH) and direct-sequence (DS) spread spectrum techniques. The total bandwidth is divided into Ns subbands. The output of a superorthogonal encoder and a pseudorandom (PN) sequence select one subband, in which the user's data is sent in the form of DS-CDMA signal using the second PN sequence. We consider soft detection at the receiver front end. We obtain the upper and lower bounds on the bit error rate for the proposed method. For comparison, we also consider the conventional DS-CDMA system. It is shown that the proposed multiple access method outperforms the conventional DS-CDMA...
Multiple-access performance analysis of combined time-hopping and spread-time CDMA system in the presence of narrowband interference
, Article IEEE Transactions on Vehicular Technology ; Volume 58, Issue 3 , 2009 , Pages 1315-1328 ; 00189545 (ISSN) ; Nasiri Kenari, M ; Sharif University of Technology
2009
Abstract
We consider a combined time-hopping (TH) and spread-time (ST) multiple-access technique that uses an internal code. In this method, the duration of each bit is divided into Ns frames. The outputs of the encoder and a pseudorandom (PN) sequence specify the number of the frame in which the data bit is transmitted in ST code-division multiple-access (ST-CDMA) form using the second PN sequence. We consider the correlator receiver, followed by the channel decoder. We obtain the performance of the combined method in additive white Gaussian noise (AWGN) and fading channels in the presence of multiple-access interference (MAI) and narrowband interference (NBI). We also consider the conventional...