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Novel simple forms for the probability density function (PDF) and the cumulative distribution function (CDF) of two correlated Rician random variables (RVs) are derived. The new representations for the bivariate Rician PDF and CDF are given in the form of single integral solutions in terms of well known functions that are available in common mathematical software packages. The general case of non-identically...
This paper analyzes the performance of space-time block coded orthogonal frequency division multiplexing (OFDM) systems. In our analysis, we abandon the usually made assumption of quasi-static channel conditions. Instead of this, we consider the more general and realistic case that the channel envelope changes during two consecutive transmission time slots. In addition, we take the spatial correlation...
This paper considers the performance of the multiuser multi-antenna downlink where NT base station antennas transmit to K non-collocated, single antenna users over correlated channels. A practical and near-capacity multi-user technique called vector perturbation precoding (VPP) is considered. For these scenarios, we derive a lower bound to the average energy of the precoded vector. We use this to...
In the next generation wireless systems, it's quite likely that a large number of user terminals are not able to transmit and/or receive over the entire system bandwidth, as much wider system bandwidth, e.g., 100 MHz, is expected to be employed in the future. As a new and challenging problem, user terminal bandwidth limitation is considered in this paper, and multiuser resource allocation for orthogonal...
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...
In this paper, we consider a half-duplex Gaussian relay channel where the noises at the relay and destination are arbitrarily correlated. For this generalized relay channel, we first evaluate the cut-set bound as well as the achievable rates with three existing relay schemes: Decode-and-Forward (DF), Compress-and-Forward (CF), and Amplify-and-Forward (AF), with performance comparison under various...
In this paper, we analyze the impact of imperfect channel estimation on the performance of pilot symbol assisted modulation (PSAM) used in a relay communication system with distributed space time block code (STBC) and amplify-and-forward protocol. We derive correlation coefficients between the channel coefficients and their estimates when the relay-to-destination link is either non-fading or fading,...
Complete shadowing modelling is one of the key issues when performing system level simulation of wireless networks. So far, models have been defined considering fixed antenna heights and a cellular deployment of base stations over roofs. However in multi-hop networks, like vehicle-to-vehicle systems, mobile equipments can be in constant three-dimensional mobility and the height of transmitter and...
Novel single integral representations for the multivariate probability density function (PDF) and cumulative distribution function (CDF) of the Nakagami-m distribution with integer and identical fading severity parameter m are derived. A generalized correlation structure is used in this model. The single integral solutions for the PDF and the CDF are given in terms of well known mathematical functions...
One way of modelling the wireless channel is in a statistical manner, based on a few parameters describing the characteristics of the environment. In most current wireless channel models, these key parameters are assumed independent between separate links, i.e. on the channels modelling the propagation between one base station and several mobile stations, or one mobile station and several base stations...
In this paper, we study the transmit precoding problem for multiple-input multiple-output (MIMO) multiple-access (MA) cellular systems employing cooperative base stations (BSs) and amplify-and-forward (AF) relaying where the antennas at the user equipments (UEs), relay terminals (RTs), and BSs are correlated. It is assumed that BSs have perfect channel state information (CSI) while user equipments...
In this paper, we carry out the performance analysis of recently proposed low complexity max log MAP detector for interference suppression under the realistic imperfections of correlation and non Gaussian alphabets. We also incorporate MMSE detector in our analysis taking into account non Gaussian alphabets however intricacy in the analysis of correlated case restricts our analysis to the case of...
Generally, optimization techniques for resource allocation of OFDMA systems are infeasible for real-time applications. In this paper, we propose a genetic algorithm with subscriber station (SS) grouping resource allocation (GGRA) scheme for IEEE 802.16 uplink systems. The GGRA scheme firstly designs a rate assignment strategy, applied with a predefined residual lifetime, to allocate resource to each...
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...
Full-rate full-diversity (FRFD) space-time block codes (STBCs), which are originally designed for independent and identically distributed (i.i.d.) multiple-input multiple-output (MIMO) channels, may suffer from severe performance degradation in the presence of channel correlation. A feasible solution is to adopt a linear precoder to match the eigen beams of these codes with that of the channels. The...
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...
In a receive diversity system the use of multiple antennas at one end of the link produces multiple channels. A useful, although ill-defined, metric for such a link is the number of independent channels provided. In this letter we discuss several candidate metrics and compare their utility. We show that most of the metrics available in the literature have limitations and can exhibit non-physical behaviour...
In a heterogeneous cognitive radio system, different secondary users may suffer from different activities of primary user, thus making a joint cooperative spectrum sensing difficult. However, there typically exists strong correlation among secondary users located close to each other, which can substantially benefit the spectrum sensing. To leverage the correlation, belief propagation (BP) is applied...
In the context of vehicular safety and entertainment applications, we focus on the design of a reliable medium access control scheme. Each vehicle is willing to form a network and regularly communicate with the other vehicles in its vicinity, forming a Vehicular Ad hoc Network (VANET). The information that is being communicated is short lived, and requires a very low probability of failure. In this...
This work considers the performance of multiple-input single-output (MISO) wireless systems employing beamforming over correlated wireless channels. More specifically, we examine the use of Random Vector Quantization (RVQ) as a limited feedback method of informing the transmitter of the appropriate beamforming vector. Using RVQ, we are able to derive the distribution functions of the beamforming gain...
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