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We consider frequency-domain equalization of single-carrier systems in doubly-selective channels. In this framework, we investigate the role of channel extension in the time domain on the performance of extended frequency-domain equalization. Specifically, we propose a new low-complexity channel extension technique, whose comparison with other techniques is performed by evaluating the approximation...
In this paper we propose a blind maximum ratio combining (MRC) technique along with an initialization method to improve the performance of the blind adaptive channel shortening algorithm called multicarrier equalization by restoration of redundancy (MERRY) in the 1times2 SIMO channel context. We show through analysis and simulations that the blind MRC technique allow us to take advantage of the spatial...
32-amplitude and phase-shift-keying (32APSK) is one of the modulation schemes proposed in the 2nd generation digital video broadcasting over satellite (DVB-S2) standard. This paper presents a non-data-aided (NDA) SNR estimation scheme for 32APSK using the expectation-maximization (EM) algorithm. Two variants of the EM algorithm are presented, first with an arbitrary initialization and a second version...
In this paper, pilot-assisted transmission over time-selective flat fading channels is studied. It is assumed that noncausal and causal Wiener filters are employed at the receiver to perform channel estimation with the aid of training symbols sent periodically by the transmitter. For both filters, the variances of estimate errors are obtained from the Doppler power spectrum of the channel. Subsequently,...
This paper proposes an OFDM receiver for the forward link of a fixed broadband satellite system. Although the satellite channel is not frequency selective, OFDM could be preferred to single carrier waveforms if it allows to improve the system spectral efficiency. The possible gain would arise from the possibility to reduce the overhead in a non-frequency selective channel. The cyclic prefix, introduced...
We present the performance evaluation of a grouped chip-level iterated (CLi) multiuser detection (MUD) technique that is based on Gaussian forcing technique for overloaded synchronous code-division multiple access systems. We confirm that the new grouped CLi MUD can approach the performance of the more complex CLi MUD with brute-force search. Also, we show that the new Grouped CLi MUD can provide...
The performance of the carrier sense multiple access/collision avoidance (CSMA/CA) protocol under the presence of carrier sensing errors is analyzed. Two types of carrier sensing errors, false alarm and miss detection, are considered, and their impact on system performance is analyzed using a new CSMA/CA model based on a Markov chain capturing the sensing errors at the physical layer. The throughput...
The study of random access protocols has recently regained attention due to new cross-layer schemes such as multipacket reception (MPR) systems and network diversity multiple access protocols (NDMA). Despite their relevance, these two systems have only been simultaneously studied employing finite user population models and considering perfect detection of the active users, which are assumptions only...
In this paper, communication over imperfectly-known fading channels with different degrees of cooperation is studied. The three-node relay channel is considered. It is assumed that communication starts with the network training phase in which the receivers estimate the fading coefficients of their respective channels. In the data transmission phase, amplify-and-forward and decode-and-forward relaying...
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