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Visible light communication (VLC) has emerged as a potential wireless connectivity solution for infrastructure-to-vehicle (I2V) communications. In this paper, we investigate the performance of I2V VLC systems with access points in the form of streetlights. Particularly, we consider a typical two-lane highway road where the light poles are located at both roadsides and uniformly separated from each other. Based on non-sequential ray tracing simulations, we first propose a closed-form path loss expression as a function of transceiver and infrastructure parameters. Then, we statistically analyze the path loss and derive a closed-form expression for its probability distribution function (PDF). Utilizing the derived PDF, we derive an approximate closed-form bit error rate (BER) expression. We confirm the accuracy of derived BER expression through comparison with Monte Carlo simulation results and demonstrate the effect of transceiver and infrastructure parameters such as receiver aperture, pole height, car height, lateral shift, and spacing between light poles on the BER performance. [ABSTRACT FROM AUTHOR]

Free space optical (FSO) communication systems provide line-of-sight wireless connectivity in the unlicensed optical spectrum and achieve higher data rates in comparison to their radio frequency (RF) counterparts. FSO systems are particularly attractive for the last mile access problem by establishing a connectivity bridge between optical fiber-based backbone and RF access networks. To address this practical deployment scenario, there has been an increasing attention on the so-called mixed (dual-hop) FSO-RF systems where FSO transmission is utilized at one hop followed by RF transmission at the other one. In this paper, we investigate the performance of mixed FSO-RF transmission systems where the FSO link is modeled by the double generalized Gamma distribution with generalized pointing error impairments and the RF link experiences the extended generalized-K shadowed fading. For both amplify-and-forward and decode-and-forward relaying, we derive closed-form expressions for outage probability, bit error probability, and ergodic capacity in terms of bivariate Fox-H function. Monte Carlo simulation results are provided to verify the accuracy of derived expressions. We further provide an asymptotic analysis and discuss the achievable diversity orders of mixed FSO-RF systems. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the performance of a cooperative vehicular network over a doubly selective fading channel using multiple antennas at source and destination vehicles. Under the assumption of amplify-and-forward (AF) relaying with orthogonal cooperation protocol and Alamouti-type space–time block coding (STBC), we derive a pairwise error probability (PEP) expression and demonstrate the achievable diversity gains. Our results demonstrate that, via proper linear constellation precoding and digital phase sweeping (DPS), the cooperative vehicular scheme is able to extract the maximum available diversity in frequency (through multipath diversity), time (through Doppler diversity), and spatial (through antenna and cooperative diversity) dimensions. We further conduct Monte Carlo simulations to confirm the analytical derivations and present the error rate performance of the vehicular scheme under various mobility conditions and scenarios. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the performance of a cooperative orthogonal frequency-division multiple-access (OFDMA) system with decode-and-forward (DaF) relaying. Specifically, we derive a closed-form approximate symbol-error-rate expression and analyze the achievable diversity orders. Depending on the relay location, a diversity order up to (LSkD + \1) +\break \summ = 1^{M}\min(LSkRm + \1, LRmD + \1) is available, where $M$ is the number of relays, and LSkD + \1, LSkRm + \1, and LRmD + \1 are the lengths of channel impulse responses of source-to-destination, source-to- $m$th relay, and $m$th relay-to-destination links, respectively. Monte Carlo simulation results are also presented to confirm the analytical findings. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the error rate performance of a cooperative network with adaptive decode-and-forward (DF) relaying over time-selective frequency-flat Rayleigh-fading channels. We assume pilot-symbol-assisted modulation (PSAM) for the estimation of time-varying fading channel coefficients. For the system under consideration, we derive an exact closed-form expression for the average bit/symbol error rate, which is further validated through Monte Carlo simulations. Such closed-form solutions are highly desirable because they allow for rapid and efficient performance evaluation. Through the derived expression, we also demonstrate the effect of various system parameters such as the number of relays, Doppler values, and filter length on system performance. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the performance of an amplify-and-forward (AF) cooperative diversity system with multiple relays in the presence of channel estimation errors. We consider both conventional relaying (in which all relay nodes participate in the relaying phase) and opportunistic relaying (in which only a single relay is allowed to participate). We derive closed-form expressions for error probability, outage probability, and ergodic channel capacity. The derivations are confirmed through Monte Carlo simulations. We further deploy the derived expressions to obtain optimal power allocation rules for performance improvements. [ABSTRACT FROM PUBLISHER]

Quasi-orthogonal space-time block codes (QO-STBCs) are a powerful code family designed for more than two transmit antennas. In contrast to their orthogonal counterparts designed for the same number of transmit antennas, QO-STBCs are able to provide full-rate transmission rate. While original QO-STBCs enjoy only a partial diversity, the recently proposed rotated versions of QO-STBCs achieve the maximum diversity order which is equal to the number of transmit antennas. Since QO-STBCs have been originally proposed for frequency-flat fading channels, it is a challenging design problem to apply them over frequency-selective channels. The dispersive nature of such channels results in intersymbol interference which needs to be carefully handled at the receiver. In this paper, we investigate time-domain equalization for QO-STBC, exploiting the embedded quasi-orthogonal structure to design low-complexity receivers. We also present diversity gains for the proposed scheme through pairwise error probability (PEP) derivation and analysis which are further confirmed by Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

In this paper, we propose an adaptive power loading algorithm for an OFDM (orthogonal frequency division multiplexing)-based multi-relay regenerative network with relay selection. The proposed scheme is based on selecting the "best" relay(s) according to different strategies and distributing the power adaptively among the subcarriers of source and selected relay(s) as to minimize an upper bound on the bit error rate (BER). Our Monte Carlo simulation results demonstrate superior performance gains through power loading with respect to conventional equal power loading schemes. The effects of imperfect channel estimation and relay location on the BER performance are further discussed. [ABSTRACT FROM AUTHOR]