Acceptable Bit Error Rate Performance Research Articles

A high‐speed single‐channel inter‐satellite optical wireless communication link incorporating spectrum‐efficient orthogonal modulation scheme

AbstractThe present work reports a novel single‐channel high‐speed inter‐satellite optical wireless communication (IsOWC) transmission link by using a 3‐D spectrum‐efficient orthogonal modulation scheme incorporating hybrid non‐return‐to‐zero‐differential quadrature phase shift keying‐polarization shift keying schemes. Three independent 40 Gbps information signals are parallel transported by modulating over distinct optical signal properties viz. amplitude, phase, and polarization of a single wavelength laser. The performance of the proposed system has been investigated by evaluating bit error rate (BER) performance of the IsOWC link vs link distance as performance metrics. Also, the link performance is numerically investigated in the presence of pointing errors. We numerically demonstrate a faithful 120 Gbps transmission at 26 000 km IsOWC link length. Further, the results report a reliable transmission up to 3.5 urad pointing error angle with acceptable BER performance of the link.

Multilayered optical OFDM for high spectral efficiency in visible light communication system

This paper presents two new schemes for improving the spectral efficiency of an optical orthogonal frequency-division multiplexing-based visible light communication (OFDM-VLC) system. The proposed schemes employed the generalized spatial modulation (GenSM) along with multi-input multi-output (MIMO) techniques as well as modified the coded modulation optical OFDM (CMO-OFDM) approach to attain more bandwidth utilization and higher spectral efficiency. The proposed multilayered/enhanced CMO-OFDM (LeCMO-OFDM) systems ensure the real-valued optical OFDM signals without using Hermitian symmetry and utilize the redundant codes existed in CMO-OFDM for further improvements in system’s spectral efficiency while ensuring acceptable bit error rate (BER) performance. LeCMO-OFDM scheme transmits multilayer optical signals after converting them to unipolar form either by using DC bias (DC-LeCMO-OFDM) or by separating them through employing the GenSM with no DC bias (NDC-LeCMO-OFDM). We present analytical and simulation results to evaluate the effectiveness of the proposed systems and demonstrate the additional capacity gain in terms of spectral efficiency. In addition, the impact of the spacing distance between the light emitting diodes has been addressed. Detailed performance comparison in terms of spectral efficiency and BER between the proposed techniques and other recent works is provided for validation purpose. Finally, results show that our schemes can achieve better spectral and power efficiencies performance with acceptable BER performance when compared with the related methods.

320 Gbps Free Space Optic Communication System Deploying Ultra Dense Wavelength Division Multiplexing and Polarization Mode Division Multiplexing

Abstract This work aims to investigate the integrated ultra-dense wavelength division multiplexing (UDWDM) and polarization division multiplexing (PDM) schemes incorporated in the free space optic (FSO) communication system. Erbium-doped fiber amplifiers (EDFAs) are used as post and pre-amplifiers in the proposed UDWDM–PDM–FSO system to boost the transmission power for increasing the distance. Thirty-two channels are transported over the FSO link to realize the total data transmission of 160 and 320 Gbps with 0.08 and 0.1 nm channel spacing, respectively. Results are also reported with non-return to zero modulation schemes. The performance of the proposed UDWDM–PDM–FSO transmission system is measured in terms of bit error rate (BER) and eye diagrams. The transmission distances are 100 and 87 km under clear weather and have acceptable BERs with 0.08 and 0.1 nm channel spacing, respectively. The weather conditions may worsen due to the increase in atmospheric turbulence. Hence, the transmission distances decrease to 3.93 and 2.6 km for heavy rain weather conditions. The UDWDM–PDM–FSO communication system exhibits an excellent performance due to the use of EDFAs with high achievable maximum distance and good and acceptable BER performance. The UDWDM–PDM–FSO communication system considerably enhances the transmission distance compared with the UDWDM–FSO communication system.

Manifold Optimization Approach for Data Detection in Massive Multiuser MIMO Systems

When the number of base station (BS) antennas is considerably larger than the number of user terminals (UTs), a simple linear minimum mean-square-error (LMMSE) data detection algorithm is near-optimal for uplink massive multiuser multiple-input and multiple-output (MIMO) systems. However, the LMMSE detector suffers significant performance loss when the number of UTs is comparable to the number of BS antennas. To alleviate the performance loss caused by the decrease in the BS-antenna-to-UT ratio, known data detection algorithm, namely “TASER,” can yield bit error rate (BER) performance close to that of the optimal detector in symmetric massive multiuser MIMO systems, where the BS-antenna-to-UT ratio is one. However, this TASER algorithm can only handle binary and quadratic phase-shift keying (PSK) modulations. Moreover, the computational complexity of the TASER algorithm is still remarkably high. Thus, a novel data detection algorithm is proposed in this study to reduce the computational complexity of the detection algorithm while achieving acceptable BER performance. The proposed algorithm is developed from the retraction-based Riemannian manifold optimization (RMO) framework for symmetric massive multiuser MIMO systems. Unlike the TASER-based detector, the proposed RMO-based detector can be applied for general $M$ -ary PSK modulations. Simulation results show that the proposed detector significantly outperforms the LMMSE detector in terms of BER performance. In addition, the required complexity of RMO is substantially lower than that of TASER. These findings indicate that the proposed RMO-based detector exhibits a highly desirable tradeoff between BER performance and complexity.

Low-Complexity Scalable Iterative Algorithms for IEEE 802.11p Receivers

In this paper, we investigate receivers for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. Vehicular channels are characterized by multiple paths and time variations, which introduce challenges in the design of receivers. We propose an algorithm for IEEE 802.11p-compliant receivers, based on orthogonal frequency-division multiplexing (OFDM). We employ iterative structures in the receiver as a way to estimate the channel despite variations within a frame. The channel estimator is based on factor graphs (FGs), which allow the design of soft iterative receivers while keeping acceptable computational complexity. Throughout this paper, we focus on designing a receiver that offers a good complexity–performance tradeoff. Moreover, we propose a scalable algorithm to be able to tune the tradeoff, depending on the channel conditions. Our algorithm allows reliable communications while offering a considerable decrease in computational complexity. In particular, numerical results show the tradeoff between complexity and performance measured in computational time and bit error rate (BER), as well as frame error rate (FER) achieved by various interpolation lengths used by the estimator, which both outperform by decades the standard least squares (LS) solution. Furthermore, our adaptive algorithm shows a considerable improvement in terms of computational time and complexity against state-of-the-art and classical receptors while showing acceptable BER and FER performance.

Unrepeated 200-km transmission of 40-Gbit/s 16-QAM signals using digital coherent receiver

We demonstrate unrepeated 200-km transmission of 40-Gbit/s 16-QAM signals using a digital coherent receiver, where the decision-directed carrier-phase estimation is employed. The phase fluctuation is effectively eliminated in the 16-QAM system with such a phase-estimation method, when the linewidth of semiconductor lasers for the transmitter and the local oscillator is 150 kHz. Finite-impulse-response (FIR) filters at the receiver compensate for 4,000-ps/nm group-velocity dispersion (GVD) of the 200-km-long single-mode fiber and a part of self-phase modulation (SPM) in the digital domain. In spite of the launched power limitation due to SPM, the acceptable bit-error rate performance is obtained owing to high sensitivity of the digital coherent receiver.

Symbol detection in spatial multiplexing system using particle swarm optimization meta‐heuristics

AbstractSymbol detection in multi‐input multi‐output (MIMO) communication systems using different particle swarm optimization (PSO) algorithms is presented. This approach is particularly attractive as particle swarm intelligence is well suited for real‐time applications, where low complexity and fast convergence is of absolute importance. While an optimal maximum likelihood (ML) detection using an exhaustive search method is prohibitively complex, PSO‐assisted MIMO detection algorithms give near‐optimal bit error rate (BER) performance with a significant reduction in ML complexity. The simulation results show that the proposed detectors give an acceptable BER performance and computational complexity trade‐off in comparison with ML detection. These detection techniques show promising results for MIMO systems using high‐order modulation schemes and more transmitting antennas where conventional ML detector becomes computationally non‐practical to use. Hence, the proposed detectors are best suited for high‐speed multi‐antenna wireless communication systems. Copyright © 2008 John Wiley & Sons, Ltd.