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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...
On the capacity of interference channel with causal and noncausal generalized feedback at the cognitive transmitter
, Article IEEE Transactions on Information Theory ; Volume 58, Issue 5 , 2012 , Pages 2813-2837 ; 00189448 (ISSN) ; Akhbari, B ; Aref, M. R ; Sharif University of Technology
Abstract
In this paper, taking into account the effect of link delays, we investigate the capacity region of the cognitive interference channel (C-IFC), where cognition can be obtained from either causal or noncausal generalized feedback. For this purpose, we introduce the causal C-IFC with delay (CC-IFC-WD) in which the cognitive user's transmission can depend on L future received symbols as well as the past ones. We show that the CC-IFC-WD model is equivalent to a classical causal C-IFC (CC-IFC) with link delays. Moreover, CC-IFC-WD extends both genie-aided and causal cognitive radio channels and bridges the gap between them. First, we derive an outer bound on the capacity region for the arbitrary...
On the devroye-mitran-tarokh rate region for the cognitive radio channel
, Article IEEE Transactions on Wireless Communications ; Volume 8, Issue 7 , 2009 , Pages 3458-3461 ; 15361276 (ISSN) ; Aref, M. R ; Sharif University of Technology
2009
Abstract
An achievable rate region for the genie-aided cognitive radio channel is obtained using the celebrated HanKobayashi jointly decoding strategy for the interference channel and the Gel'fand-Pinsker coding scheme for channels with side information known at the transmitter. The achievable rate region is then simplified by Fourier-Motzkin elimination. The obtained achievable rate region (i) extends the Chong-Motani-Garg region for the interference channel to the cognitive channel and (ii) is a simplified description of the Devroye-Mitran-Tarokh rate region for the genie-aided cognitive radio channel. © 2009 IEEE