Closed-form Error Rate Expressions Research Articles

Dual-hop communications over PLC/η-μ and PLC/λ-μ fading channels

ABSTRACT In this study, the performance analysis of dual-hop power line communication (PLC)/ and PLC/ L-branch systems by using the decode-and-forward (DF) protocol is presented in detail. The introduced work provides novel closed-form expressions of the probability density function (PDF) of the instantaneous signal-to-noise ratio (SNR) of the considered systems. Taking the proposed PDFs into account, we also derive closed-form expressions of the error rate and channel capacity (CC) performance for the dual-hop PLC/ and PLC/ L-branch DF systems. Furthermore, an exhaustive comparative study of different modulation types such as non-coherent M-ary frequency-shift keying, square quadrature amplitude modulation (SQAM), and cross quadrature amplitude modulation (×QAM) is presented by using the proposed closed-form error rate expressions. Also, the exact expressions for the CC with channel inversion with a fixed-rate (CIFR) transmission policy are proposed. Finally, all the theoretical findings are confirmed through numerical results obtained by using the exact expressions.

Exact Error Rate of Dual-Channel Receiver with Remote Antenna Unit Selection in Multicell Networks

The error rate performance of circularly distributed antenna system is studied over Nakagami-m fading channels, where a dual-channel receiver is employed for the quadrature phase shift keying signals detection. To mitigate the Co-Channel Interference (CCI) caused by the adjacent cells and to save the transmit power, this work presents remote antenna unit selection transmission based on the best channel quality and the maximized path-loss, respectively. The commonly used Gaussian and Q-function approximation method in which the CCI and the noise are assumed to be Gaussian distributed fails to depict the precise system performance according to the central limit theory. To this end, this work treats the CCI as a random variable with random variance. Since the in-phase and the quadrature components of the CCI are correlated over Nakagami-m fading channels, the dependency between the in-phase and the quadrature components is also considered for the error rate analysis. For the special case of Rayleigh fading in which the dependency between the in-phase and the quadrature components can be ignored, the closed-form error rate expressions are derived. Numerical results validate the accuracy of the theoretical analysis, and a comparison among different transmission schemes is also performed.

Enabling Cooperative Relaying VANET Clouds Over LTE-A Networks

This paper addresses the area of heterogeneous wireless relaying vehicular clouds. We devise an advanced vehicular relaying technique for enhanced connectivity in densely populated urban areas. We investigate the performance of a transmission scheme over a Long-Term Evolution-Advanced (LTE-A) network where vehicles act as relaying cooperating terminals for a downlink session between a base station and an end-user. The abundance of moving vehicles, operating in an ad hoc fashion, can eliminate the need for establishing a dedicated relaying infrastructure. However, the associated wireless links in vehicular clouds are characterized by a doubly selective fading channel; this causes performance degradation in terms of increased error probability. Hence, we propose a precoded cooperative transmission technique to extract the underlying rich multipath–Doppler-spatial diversity, which is a relay selection scheme to take advantage of the potentially large number of available relaying vehicles. We further contribute by the derivation of a closed-form error rate expression, diversity gain, and outage expressions and introduce our derived performance unconditional expressions as a benchmark to assess our analysis and future research studies of such an approach. Our analytical and simulation results indicate that significant diversity gains and reduced error rates are achievable. In addition, there is a noticeable reduction in the required transmitting power compared with traditional transmission schemes, as well as an increase in distance coverage.

Average Error Rate Expressions for DF relay Networks with CE Error for PSA-CE schemes Over Rayleigh Fading Channels

This paper provides a framework for evaluating the error rate performance of decode and forward (DF) relay cooperative transmission in the presence of channel estimation (CE) error caused by pilot symbol assisted-channel estimation (PSA-CE) schemes over Rayleigh fading channels. Average bit error rate (BER) and average symbol error rate (SER) are expressed as the well-known closed-forms by using error-events at relay nodes and moment generating function (MGF) of the received signal-to-noise ratio (SNR), which quantifies the SNR penalty arising from CE errors. Moreover, the effects of erroneous detection and transmission at relay nodes are verified in terms of both the combined SNR and the average error rate, and cooperative diversity is observed from closed-form error rate expressions. Simulation results are finally presented to validate derived analytical performance ma-trices.

MIMO Architecture for Coherent Optical Wireless Communication: System Design and Performance

A coherent multiple-input multiple-output architecture is proposed for optical wireless communications (OWCs) to mitigate atmospheric turbulence effects. Transmitter optical signals operate at distinct carrier frequencies to allow the received optical signals to be separately processed. The accumulated phase noise in each transmission branch can then be independently and electrically compensated. Based on the proposed architecture, several diversity combining techniques are used at the receiver end for system performance evaluation. Three different turbulence models are considered in this paper for different scintillation level ranges, including gamma-gamma turbulence, K-distributed turbulence, and negative exponential turbulence. Closed-form error rate expressions are derived using a series expansion approach. The diversity order in the gamma-gamma turbulence channel is found to depend only on the smaller channel parameter, while the K-distributed and negative exponential turbulence channels are found to have the same diversity order. The presented numerical results demonstrate substantial system performance improvement over single-link coherent OWC.

Optical Communication Using Subcarrier Intensity Modulation in Strong Atmospheric Turbulence

Error rate performance of subcarrier intensity modulations is analyzed for optical wireless communications over strong atmospheric turbulence channels. We study the error rate of a subcarrier intensity modulated optical wireless communication system employing M -ary phase-shift keying, differential phase-shift keying, and noncoherent frequency-shift keying. Both K -distributed turbulence channel (strong) and negative exponential turbulence channel (saturated) are considered. Closed-form error rate expressions are derived using a series expansion of the modified Bessel function. Furthermore, the outage probability expressions are obtained for subcarrier intensity modulated optical wireless communication systems over the K-distributed turbulence and the negative exponential channels. Asymptotic error rate analysis and truncation error analysis are also presented. Our asymptotic analysis shows that differential phase-shift keying suffers a constant signal-to-noise ratio performance loss of 3.92 dB with respect to binary phase-shift keying under strong atmospheric turbulence conditions. The numerical results demonstrate that our series solutions are efficient and highly accurate.

Subcarrier Intensity Modulated Wireless Optical Communications With Rectangular QAM

The average symbol error rate is studied for subcarrier intensity modulated wireless optical communication systems employing general order rectangular quadrature amplitude modulation. We consider three different turbulence channel models, i.e., the Gamma–Gamma channel, the K-distributed channel, and the negative exponential channel with different levels of turbulence. Closed-form error rate expressions are derived using a series expansion of the modified Bessel function. In addition, detailed truncation error analysis and asymptotic error rate analysis are also presented. Numerical results demonstrate that our series solutions are highly accurate and efficient.

Error Rate of Subcarrier Intensity Modulations for Wireless Optical Communications

Subcarrier intensity modulations are analyzed for the Gamma-Gamma turbulence channels. We study the error rate of a subcarrier intensity modulated wireless optical communication system employing phase-shift keying, differential phase-shift keying, and noncoherent frequency-shift keying. Closed-form error rate expressions are derived using a series expansion approach. Asymptotic error rate analysis and truncation error analysis are also presented. Our asymptotic analysis shows that the diversity order of the system and the signal-to-noise ratio penalty factors for noncoherent modulations depend only on the smaller channel parameter.

Performance analysis of coherent wireless optical communications with atmospheric turbulence

Coherent wireless optical communication systems with heterodyne detection are analyzed for binary phase-shift keying (BPSK), differential PSK (DPSK), and M-ary PSK over Gamma-Gamma turbulence channels. Closed-form error rate expressions are derived using a series expansion approach. It is shown that, in the special case of K-distributed turbulence channel, the DPSK incurs a 3 dB signal-to-noise ratio (SNR) penalty compared to BPSK in the large SNR regime. The outage probability is also obtained, and a detailed outage truncation error analysis is presented and used to assess the accuracy in system performance estimation. It is shown that our series error rate expressions are simple to use and highly accurate for practical system performance estimation.

Error performance of a pulse amplitude and position modulated ultra-wideband system over lognormal fading channels

In this paper, the error performance of an ultra-wideband (UWB) system with a hybrid pulse amplitude and position modulation (PAPM) scheme over indoor lognormal fading channels is analyzed. In the PAPM UWB system, input data is modulated onto both the pulse amplitudes and pulse positions. The receiver employs a RAKE to combine energy contained in the resolvable multipath components. Derivation of closed-form error rate expressions of the system in lognormal fading channels is based on approximating a sum of independent lognormal random variables (RV) as another lognormal RV using the Wilkinson method. Given the same delay spread of the channel, the proposed PAPM scheme can provide a higher throughput than the binary pulse amplitude or pulse position modulation scheme.