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ABSTRACT: Outage analysis of cooperative space-time block coding (STBC) multiple-input multiple-output (MIMO) relaying system with a single relay is discussed in this paper. The source node, equipped with two transmit antennas, broadcasts each STBC code to the relay and the destination nodes. Then, the relay node also equipped with multiple antennas, amplifies-and-forwards (AF) the received STBC codes. Finally, the destination node uses maximum ratio combining (MRC) and exploits the diversity gain obtained through the direct and the indirect links simultaneously. Lower bounds of the outage probability is derived using the moment generating function (MGF) of the total signal-to-noise ratio (SNR) for a particular signal of M-ary-quadrature-amplitude modulation (M-QAM). Simulation results are provided to verify the validity of the analytical results.
Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd; 10/2010
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ABSTRACT: This paper presents performance analysis of a cooperative multiple-input-multiple-output (MIMO) relaying system with a single relay. In this scheme, each link uses MIMO Alamouti space-time block coding (STBC) over Rayleigh flat-fading channels. The particularity of the proposed scheme is that, during a first time slot, the source node broadcasts each STBC to the relay and destination nodes. During the second time slot, the relay node amplifies-and-forwards (AF) the received STBCs. Finally, the receiver at the destination node exploits the diversity gain that is obtained through the direct and indirect links simultaneously by applying maximum ratio combining (MRC) on the received signals. Using the SNR for the direct link and an upper bound of the SNR for the indirect link, the moment-generating function (MGF) of the SNR for the cooperative link is derived. Since this MGF is based on an upper bound of the SNR, it is then employed to derive a lower bound of the symbol error probability (SEP) for a particular signal of M-ary quadrature-amplitude modulation (M-QAM). Subsequently, simulation results of the SEP are presented to illustrate the performance improvement given by the MIMO cooperative diversity system based on the STBC scheme.
IEEE Transactions on Vehicular Technology 10/2010; · 1.92 Impact Factor
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ABSTRACT: This paper presents robust unsupervised decision feedback equalizer (DFE) for acoustic underwater communications. The proposed equalizer consists of the cascade of four devices whose main components are recursive (7?.) and transverse (T) filters. The feature of the given equalizer is the ability to deal with severe quickly time varying channels by allowing the adjustment of both, its structure and its adaptation according to a mean square error (MSE) criterion. In the existing solution, the recursive and transverse filters are updated by decision directed least-mean-square (LMS) algorithms. However, the weakness of the LMS like algorithms against the time varying environments pushes us to improve the adaptation by the use of other robust solutions. In this paper, we propose the employ of normalized LMS algorithms with self step-size regularization based on complex-valued generalized normalized gradient descent (GNGD) method instead of simple LMS algorithms. Compared to the existent unsupervised DFE, the proposed solution gives the best performance in channel tracking despite the irregularities and the non-stationarity of the environment. Performance analysis are given in terms of the MSE for both synthetic and realistic channels obtained from underwater acoustic recorded signals.
OCEANS 2009, MTS/IEEE Biloxi - Marine Technology for Our Future: Global and Local Challenges; 11/2009
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ABSTRACT: In this paper, we introduce a collaborative minimum mean squared error (MMSE) interference canceler in MIMO relay networks. The proposed receiver architecture is characterized by the integration of the generalized minimum residual method (GMRES) for symbol detection. In this scheme, the GMRES method detects the transmitted symbols by solving iteratively a linear system representing the MMSE interference canceler without matrix inversion. The relay-destination channels are assumed to be orthogonal. We evaluate the instantaneous capacity of the equivalent MIMO relay network equipped with K parallel relay nodes for TDMA and MC-CDMA modes, using the assumption that the source node does not communicate directly with the destination node. In order to evaluate the system performances, the bit error rate (BER) is evaluated with respect to the number of relay nodes K and the signal to noise ratio (SNR) measured at the destination.
Global Telecommunications Conference, 2008. IEEE GLOBECOM 2008. IEEE; 01/2009
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ABSTRACT: The success of MIMO technology has led to the concept of cooperative communications where multiple single-antenna nodes can share their antennas in order to create a distributed ¿virtual¿ MIMO system. The basic idea of Multiple Input Multiple Output systems is to create spatial diversity transmitting signals from different locations. This elementary concept is the basis of cooperative communications. In this paper, a brief state of the art of cooperative communications is first presented. The concept is then applied to a wireless transmission scenario between an urban bus and a control centre with a relay for video surveillance applications. We consider either theoretical or realistic propagation channels: 1) Rayleigh channels on all three links, or 2) a Rice channel between the relay and the destination and a suburban channel for the other links. It will be shown that cooperative communications prove to be particularly interesting to extend the coverage range.
ITS Telecommunications, 2008. ITST 2008. 8th International Conference on; 11/2008
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ABSTRACT: In this paper, we propose a reduced complexity interference canceler for a Turbo Space-Time Codes (TSTC) receiver. Actually, the TSTC receiver is based on a linear Minimum Mean Squared Error (MMSE) filter inside an Interference Canceler (IC) loop. In this scheme, considering the matrix inversion cost, the overall complexity remains important for a large number of transmit and receive antennas. In the proposed receiver, we integrate the Generalized Minimum residual method (GMRES) for symbol detection to compute the MMSE filter without matrix inversion. A good tradeoff between performances and complexity is thus achieved for a system with a large number of transmit and receive antennas. The bit error ratio (BER) and the complexity are evaluated with respect to the number of iterations of the GMRES and the number of transmit/receive antennas. A comparison with the existent IC-MMSE is presented and discussed at the end of the paper.
Signal Processing and Information Technology, 2007 IEEE International Symposium on; 01/2008
