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An internally coded time-hopping spread-time CDMA scheme for UWB systems and its performance analysis
, Article 2007 IEEE Radio and Wireless Symposium, RWS, Long Beach, CA, 9 January 2007 through 11 January 2007 ; 2007 , Pages 511-514 ; 9781424404452(ISBN) ; Nasiri Kenari, M ; Sharif University of Technology
2007
Abstract
We consider an internally coded multiple access technique for Ultra Wide-Band systems which combines time-hopping (TH) and spread-time (ST) techniques using a super-orthogonal encoder. In this method, the duration of each bit is divided into Ns frames. The outputs of a superorthogonal encoder and a PN sequence specify the frame number, in which the data is transmitted in spread-time CDMA form using the second PN sequence. We consider soft decision before Viterbi decoding at the receiver. We obtain the performance of the proposed method. We also consider the uncoded ST-CDMA system and compare its performance with our method. The results indicate that our method has much more better...
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...