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A new adaptive algorithm, called LLMS, which employs an array image factor, AI, sandwiched in between two Least Mean Square (LMS) sections, is proposed for different applications of array beamforming. The convergence of LLMS algorithm is analyzed, in terms of mean square error, in the presence of Additive White Gaussian Noise (AWGN) for two different modes of operation; namely with either an external...
The Nakagami-lognormal distribution is the commonly used composite distribution for modeling multipath fading and shadowing. In this paper, simple and new form of distribution which can accurately represent both the mutlipath fading and shadowing effects is introduced. The signal-to-noise ratio (SNR) of the Nakagami-lognormal distribution follows the gamma-lognormal distribution, which is accurately...
Precoding is introduced as an excellent choice for complementing the MIMO systems. In addition, the non-linear techniques can achieve near optimal capacity at the expense of reasonable levels of complexity. Such techniques show that any known interference at the transmitter can be subtracted at the receiver without the penalty of degrading the radio resources. However, precoding is subject to the...
The keyhole phenomenon, i.e., uncorrelated but rank-deficient fading, can lead to significant performance degradations in multiple-input multiple-output (MIMO) systems and has to be carefully taken into account for system design. In this paper, considering the practically important case of two transmit and an arbitrary number of receive antennas, we provide a simple closed-form expression for the...
This paper presents a new upper bound on the end-to- end signal-to-noise ratio (SNR) of channel-assisted amplify-and-forward (AF) multi-hop relay networks. The harmonic mean of the minimum of the first P >= 0 hop SNRs and the minimum of the remaining hop SNRs forms the new bound. Closed-form expressions are derived for the cumulative distribution function and the moment generating function of this...
We consider the application of switch-and-stay transmit diversity (SSTD) to a three-node cooperative diversity system with decode-and-forward relaying. The basic idea of SSTD generally is to use a certain transmit antenna as long as the induced signal quality satisfies a given requirement while the transmitter switches to another antenna element if this is no longer the case. Applying this principle...
In this paper, we propose an output-threshold multiple relay selection scheme for dual-hop multi-branch cooperative wireless networks. The proposed scheme selects the first Lc arbitrary ordered relays out of L relays such that the maximal ratio combined signal-to-noise-ratio (SNR) of the Lc relayed paths and the direct path barely exceeds a preset threshold. Closed-form expressions are derived for...
Wireless amplify-and-forward relay networks in which the source communicates with the relays and destination in the first phase and the relays simultaneously forward signals to the destination in the second phase over uncorrelated Rayleigh fading channels are considered. We examine the scenario in which each relay only knows the perfect information of its source-relay channel while the destination...
In this paper, we investigate the correlation properties of the squared envelope of a class of autocorrelation-ergodic (AE) sum-of-cisoids (SOC) simulation models for mobile Rayleigh fading channels. Novel closed-form expressions are presented for both the ensemble and the time-averaged autocorrelation functions (ACFs) of the simulation model's squared envelope. Basing on those expressions, we show...
Cooperative diversity has recently been proposed as a promising technology to achieve spatial diversity in wireless networks. In this paper, we analyze the performance of SNR-based hybrid decode-amplify-forward (HDAF) relaying cooperative diversity networks over independent non-identical flat Rayleigh fading channels with maximum ratio combining (MRC) technique. Closed-form expressions for the outage...
This paper presents blind channel estimation for Alamouti coding operating in time-correlated Rayleigh channels. A decision algorithm first obtains primary data estimates of the transmitted symbols based on the constrained linear minimum mean square error criterion, and these are applied to subsequent optimal minimum mean square error channel estimation. Performance is evaluated by simulation under...
We derive detection metrics for soft-output diversity combining for the case of imperfect channel state information at the receiver. We treat in particular the case when the noise variance at the receiver is unknown. We contrast conventional training-based methods to a detector based on the generalized likelihood-ratio (GLR) test paradigm. We study the performance of the detectors via EXIT chart analysis...
In this paper, a transmission strategy of fountain codes over cooperative relay networks is proposed. When more than one relay nodes are available, we apply network coding to fountain-coded packets. By doing this, partial information is made available to the destination node about the upcoming message block. It is therefore able to reduce the required number of transmissions over erasure channels,...
A signal-plus-noise (S + N) energy selection diversity combining (S + N-ESC) scheme for M-ary phase shift keying (MPSK) and 16-quadrature amplitude modulation (16-QAM) signaling in Nakagami-m and Rician fading channels is studied. The S + N-ESC selects the branch with the maximum S + N energy for detection. The advantage of the S + NESC scheme is that it requires no explicit channel estimation for...
In this paper, we have studied the energy efficiency of cooperative networks operating in either the fixed Amplify-and-Forward (AF) or the selective Decode-and-Forward (DF) mode. We consider the optimization of the M-ary quadrature amplitude modulation (MQAM) constellation size to minimize the bit energy consumption under given bit error rate (BER) constraints. In the computation of the energy expenditure,...
In this paper, we present a practical adaptive multiple-input multiple-output (MIMO) transmission approach for broadband wireless multiuser systems. The proposed scheme adaptively switches between open-loop and closed-loop MIMO modes, depending on the users' channel conditions and required rates, as a means to enhance the system throughput and performance. Each mode is a combination of a MIMO transmission...
Wireless cooperative relay is an efficient way in obtaining diversity in distributed manner, and it can also be used as a way in extending the cell coverage in cellular systems. In this paper, assuming receiver channel state information (CSI) only, the ergodic and outage capacity analysis are presented for amplify-and-forward (AF) multiple-input multiple-output(MIMO) relay channels deploying orthogonal...
We consider the joint exploitation of coding and diversity techniques to achieve efficient, reliable wireless transmission. The system of interest comprises a powerful non-binary low-density parity-check (LDPC) code that will be soft-decoded to supply strong error protection, a quadratic amplitude modulator (QAM) that directly takes in the non-binary LDPC symbols and will be soft-demodulated, and...
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