Achievable Bit Error Rate Research Articles

Intelligent Reflecting Surface Aided NOMA-HARQ Based IoT Framework for Future Wireless Networks

<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In sixth-generation (6G) wireless networks, non-orthogonal multiple access (NOMA) technology is widely used to improve the spectrum efficiency. Along with NOMA, hybrid automatic repeat request (HARQ) technique is used to enhance the reliability of communication system. Recently, intelligent reflecting surfaces (IRS) are a futuristic transmission technology that can achieve high spectral and energy efficiency at low cost. In this paper, an IRS aided downlink NOMA-HARQ based Internet of Things (IoT) framework is proposed to enhance the IoT devices' performance in non-line-of-sight (NLoS) region. Further, to enhance the performance of NLoS IoT device/users, two NOMA-HARQ aided IRS schemes are proposed namely: NOMA-selection combining (SC) with IRS and NOMA-maximum ratio combining (MRC) with IRS. This paper formulates and examines the IoT user/device performance in terms of the achievable data rates, outage probability, bit error rate (BER) and diversity order in IRS aided downlink NOMA-HARQ environment with variable signal-to-noise ratio (SNR). With the help of the simulation results, it is demonstrated that in dynamic wireless channels, the proposed schemes outperform the conventional NOMA with HARQ (NOMA-HARQ) in terms of achievable data rates, outage probability, BER and diversity order.</b>

Performance Analysis of Intelligent Reflecting Surface Assisted Wireless Communication System

In this paper, we investigate the end-to-end performance of intelligent reflecting surface (IRS)-assisted wireless communication systems. We consider a system in which an IRS is deployed on a uniform planar array (UPA) configuration, including a large number of reflecting elements, where the transmitters and receivers are only equipped with a single antenna. Our objective is to analytically obtain the achievable ergodic rate, outage probability, and bit error rate (BER) of the system. Furthermore, to maximize the system’s signal-to-noise ratio (SNR), we design the phase shift of each reflecting element and derive the optimal reflection phase of the IRS based on the channel state information (CSI). We also derive the exact expression of the SNR probability density function (p.d.f.) and show that it follows a non-central Chi-square distribution. Using the p.d.f., we then derive the theoretical results of the achievable rate, outage probability, and BER. The accuracy of the obtained theoretical results is also verified through numerical simulation. It was shown that the achievable rate, outage probability, and BER could be improved by increasing the number of reflecting elements and choosing an appropriate SNR regime. Furthermore, we also find that the IRS-assisted communication system achieves better performance than the existing end-to-end wireless communication.

Efficient Timing Offset Estimation Method Tailored for ACO-OFDM VLC Systems

The asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM)-based visible light communication (VLC) system has received widespread attention due to its capability to support high spectrum efficiency as well as high power efficiency. The accuracy of symbol timing offset estimation is a critical factor limiting the performance of ACO-OFDM. In order to cope with this challenge, a training symbol-aided symbol timing synchronization method tailored for ACO-OFDM is put forward. The influence of the design of training symbol structure and timing metric on the synchronization accuracy is investigated, and three timing metrics are presented to supply simple and efficient timing offset estimation by utilizing the structure of odd-even mirror-symmetric and complementary symmetric of the newly designed training symbol. In addition, the system bit error rate (BER) penalty induced by timing synchronization error is analyzed, and the approximate relationship between BER performance loss and timing estimation error probability and ideal BER performance is presented. Simulation is used to assess the performance of the three proposed timing metric methods in different channel environments, and they are compared with the two existing timing synchronization algorithms in ACO-OFDM, namely the modified Park method and the Tian method. The results show that the new synchronization method is superior to the comparison methods concerning achievable synchronization accuracy and system BER penalty.

Space-Time Block Coded Spatial Modulation for Indoor Visible Light Communications

Visible light communication (VLC) has been recognized as a promising technology for handling the continuously increasing quality of service and connectivity requirements in modern wireless communications, particularly in indoor scenarios. In this context, the present work considers the integration of two distinct modulation schemes, namely spatial modulation (SM) with space time block codes (STBCs), aiming at improving the overall VLC system reliability. Based on this and in order to further enhance the achievable transmission data rate, we integrate quasi-orthogonal STBC (QOSTBC) with SM, since relaxing the orthogonality condition of OSTBC ultimately provides a higher coding rate. Then, we generalize the developed results to any number of active light-emitting diodes (LEDs) and any <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$M$</tex-math></inline-formula> -ary pulse amplitude modulation size. Furthermore, we derive a tight and tractable upper bound for the corresponding bit error rate (BER) by considering a simple two-step decoding procedure to detect the indices of the transmitting LEDs and then decode the signal domain symbols. Notably, the obtained results demonstrate that QOSTBC with SM enhances the achievable BER compared to SM with repetition coding (RC-SM). Finally, we compare STBC-SM with both multiple active SM (MASM) and RC-SM in terms of the achievable BER and overall data rate, which further justifies the usefulness of the proposed scheme.

Optimal receive beamforming in spatial antenna diversity system using evolutionary genetic algorithm

Frequent packet loss and power inadequacy are the major issues in wireless fading networks owing to the deep fading effects and inefficient resource utilization caused by unoriented information forwarding mechanisms. Diversity techniques are potentially employed in wireless communication systems to combat the impact of fading and reinforce the desired service level guarantees for data transmission. In this work, we employ spatial diversity and antenna beamforming methods to significantly improve the signal quality performance of wireless networks and enhance the reliability by decreasing the bit error probability. A constrained optimization problem is formulated for alleviating the net noise power integrated with the adaptive beamforming vector and ameliorated channel state information. For this, the evolutionary genetic algorithm scheme is iteratively implemented for evaluating the optimal solution of the proposed optimization problem. The influence of various selection functions in the application of genetic algorithm is investigated for effective heuristic modeling design and searching through the feasible solution space. Through extensive simulation results, several crucial network parameters characterizing the proficiency of wireless communications including the noise power, signal-to-noise ratio (SNR), bit error rate (BER) are estimated and analyzed for varying number of antennas deployed at the receiver node. Furthermore, the performance of the proposed genetic algorithm based optimization technique is compared with the existing models using the key channel quality metrics of achievable SNR, BER, and model computational complexity. • Spatial diversity and receive beamforming techniques can be jointly implemented. • This optimization model achieves enhanced signal quality and reliability performance. • Evolutionary genetic algorithm solves the problem using intelligent heuristic design. • Disparate selection functions exhibit different iterative complexity for optimization. • Simulation is used to show the improved noise power, SNR, BER with evolving antennas.

Efficient differential signalling with reduced background radiation for multiple aperture FSO communication systems

The main objective of this study consists in reducing the correlated background radiations along with minimising the bit error rate (BER) for a multiple aperture free-space optical (FSO) communication system based on differential signalling scheme. Instead of performing the conventional equal gain combining (EGC) of the two wavelengths, here, the authors propose to efficiently combine them at the receiver by using non-equal channel-dependent weighting factors. To this aim, they first derive the analytic expression of the BER of the considered system, which is necessary for optimising the background radiations. Second, by considering ON–OFF keying modulation, they optimise the decision threshold and the weighting factors of the two wavelength by minimising the BER. The performance merit of the proposed scheme is contrasted to the zero threshold scheme and to the EGC scheme in terms of the average BER, the average signal-to-noise ratio (SNR) and the background rejection at the receiver. They show that the proposed scheme can improve the SNR up to 17 dB, based on the correlation coefficient of the background radiations at two wavelengths. Moreover, simulation results confirm the superiority of the proposed scheme in terms of achievable BER compared to the aforementioned conventional methods.

Health monitoring scheme‐based Forster resonance energy transfer nanocommunications in the Internet of Biological Nanothings

SummaryIn this paper, a health monitoring approach for a targeted drug delivery (TDD) system taking into consideration the binding of drug to a target cell is proposed. The proposed scheme is mainly based on Forster resonance energy transfer (FRET) nanocommunications and the physical phenomenon such as protein–protein interactions in biological systems, in order to propose a molecular communication system with various forms for single and/or multiple ligand–receptor binding. Inspired by classical wireless communication system, the analysis of proposed scheme in terms of bit error rate (BER) and mutual information between the transmitter nanomachine (TN) and receiver nanomachine (RN) is presented. Subsequently, we are able to obtain a closed‐form expression for BER for the proposed scheme. The proposed scheme can be employed in the promising Internet of Biological Nanothings (IoBNT) paradigm. The numerical results reveal that the proposed scheme with multiple donors multiple acceptors system analogous to multiple input multiple output (MIMO) communication system is a superior scheme for transmission therapeutic drug information with achievable BER.

Characterization and Performance Improvement of Cooperative Wireless Networks With Nonlinear Power Amplifier at Relay

In this paper, the performance of the cooperative cognitive radio network with the amplify-and-forward protocol is studied when the relay uses a nonlinear power amplifier (NLPA). Furthermore, taking the pulse shaping filter for the data signal into account, the power of the adjacent channel interference (ACI) to the primary users (PUs) caused by the spectral regrowth of the relay output signal is analytically calculated. Moreover, two compensation techniques are proposed which are implemented at the destination receiver to deal with the in-band nonlinear interference. The first technique is based on the calculation of the distorted signal constellation to enhance the performance of the demodulator. The second technique is feedforward compensation at the receiver. The bit error rate (BER) expressions for both techniques are presented. The ACI resulting from the spectral regrowth due to the relay NLPA is investigated by the simulation and numerical studies, and then, the BER performance degradation at the destination node and the performance improvement resulting from the proposed compensation methods are evaluated. Since the ACI confines the transmit power due to the interference power constraint of the PU, the achievable BER of the secondary user (SU) is studied. The simulation results show that the feedforward compensation technique has better BER performance than the modified constellation based approach.

BER Analysis of NOMA-Enabled Visible Light Communication Systems With Different Modulations

Visible light communication (VLC) and non-orthogonal multiple access (NOMA) are deemed two promising technologies in the next generation wireless communication systems in achieving high capacity and massive connectivity. In this paper we study the performance of a NOMA-enabled VLC system using different modulation schemes. In particular system level bit error rate (BER) is derived for different modulation schemes. Conventional methods used for analyzing the BER under orthogonal multiple access cannot be directly applied to NOMA. In order to obtain the closed-form BER expressions for the NOMA-enabled VLC systems, an analytical framework based on bitwise-decision axis and signal space is proposed.Moreover, the analysis method can be extended to the any wireless communication networks with NOMA. Simulation results demonstrate the accuracy of the theoretical analysis. The study shows that the BER gap among users decreases with the increase of the modulation order but at the cost of a higher power consumption in order to achieve a better signal to noise ratio. It is observed that 8-PSK modulation in NOMA-enabled VLC systems strikes a good tradeoff between the power cost and the achievable BER.

A study of analog decision feedback equalization for ADC-Based serial link receivers

High-speed serial link receivers based on analog-to-digital converters (ADCs) provide better programmability with different channel characteristics and the possibility of employing powerful signal equalization techniques in the digital domain. However, complexity and power consumption are still major issues in adopting such receivers in high-speed applications when compared to traditional binary or mixed-signal approaches. Embedded decision feedback equalization (DFE) before ADC quantization can relax the design requirements of both the ADC and post-ADC digital processing. This paper studies the impact of embedded analog DFE on voltage margin improvement of an ADC-based receiver through worst-case analysis. An analytical expression for the link bit-error-rate (BER) with analog DFE is derived and validated through simulations. An empirical study is conducted that evaluates the achievable BER of embedded analog DFE as a function of the channel inter-symbol interference (ISI) and ADC resolution. A channel-dependent parameter is introduced and employed to quantify the BER improvement achieved by embedding analog DFE in a receiver. A prototype receiver with embedded DFE is designed and laid out in a 130 nm CMOS process and achieves 4.64-bits peak ENOB and 4.08 pJ/conv.-step FOM at a 1.6-GS/s sampling rate. The BER performance of the receiver over high-loss FR4 channels at 1.6 Gb/s is evaluated and used to validate the simulation results.

Performance Enhancement of HAP-Based Relaying M-PPM FSO System Using Spatial Diversity and Heterodyne Detection Receiver

Abstract In this paper, we investigate the performance of a high-altitude platform (HAP)-based relaying free-space optical communication (FSO) system, where HAP plays a role as a relay node that employs detect-and-forward relaying scheme to connect between two ground stations (GSs). M $M$ -ary pulse-position modulation (PPM), spatial diversity, and heterodyne detection receiver are used to improve the system’s performance. Instead of using multiple-input multiple-output (MIMO), which makes the HAP complex, multiple-input single-output (MISO) is applied to the uplink while single-input multiple-output (SIMO) is utilized for the downlink. Consequently, the HAP only needs a couple of transmit and receive aperture. The expression for the bit error rate (BER) of the proposed FSO system is derived considering the impact of atmospheric attenuation and turbulence. The achievable BER with low values has proved the feasibility of our proposed system. In addition, the advantages of using M $M$ -PPM, spatial diversity, and heterodyne detection are demonstrated in terms of the power gain and the geometric distance between two GSs. Other useful information for system design regarding the required transmitted power, the number of transmit/receive apertures, the modulation level, and the local oscillator power is also provided in this paper.

Spatial Scattering Modulation for Uplink Millimeter-Wave Systems

In this letter, a new spatial scattering modulation (SSM) is proposed for uplink millimeter-wave (mmWave) systems that support a single user terminal (UT). By utilizing the analog and hybrid beamforming with a large antenna array and phase shifters for mmWave communications systems, an architecture, where the UT has a single radio-frequency (RF) chain, whereas the base station has more than one RF chain, is adopted. In this architecture, the proposed SSM modulates some information bits on the spatial directions of scattering clusters in the angular domain, so that a higher spectral efficiency can be achieved with the use of a lower order modulation. For a particular number of scattering clusters and a number of RF chains, a closed-form expression for the upper bound on the bit-error rate (BER) is derived for the proposed SSM. Monte Carlo simulations are also conducted to verify the achievable BER performance.

Comparison of OFDM and Ideal SC-DFE Achievable Rates and Performances Without Channel Knowledge at the Transmitter

This paper provides an achievable rate and performance analysis between OFDM and cyclic prefixed SC-DFE when no channel knowledge is available at the transmitter. Through some algebraic manipulation of the OFDM and SC-DFE capacities and using the Jensen's inequality, we prove that the SC-DFE achievable rate is always superior to that of an OFDM scheme for 4- and 16-QAM for any given channel. For higher-order modulations, however, the advantage of the ideal SC-DFE is much smaller and also the results indicate that OFDM may surpass the ideal SC-DFE achievable rate by a small amount in some specific scenarios. Finally, we provide simulation results in order to assess, corroborate and illustrate the analytical results in terms of achievable rate and bit-error rate, where we conclude that a well designed OFDM system can be, in practical context, as effective as an ideal SC-DFE but with much smaller complexity when compared to a SC-DFE implementation with error-propagation mitigation.

Dual-Mode Index Modulation Aided OFDM With Constellation Power Allocation and Low-Complexity Detector Design

Dual-mode index modulation aided orthogonal frequency division multiplexing (DM-OFDM) is recently proposed, which modulates all subcarriers to eliminate the limits of spectrum efficiency (SE) in OFDM with index modulation (OFDM-IM). In DM-OFDM, the subcarriers within each subblock are divided into two groups, which are modulated by two distinguishable constellation alphabets drawn from the inner and the outer constellation points of a given M-ary QAM constellation. In this paper, a new DM-OFDM scheme, called DM-OFDM with constellation power allocation (DM-OFDM-CPA) is proposed, where the two groups of subcarriers within each subblock are set at different power levels and modulated by different M-ary PSK symbols, leading to the improvement of the system performance at low-order modulation. At the receiver, a low-complexity maximum likelihood (LC-ML) detector and two reduced search complexity detectors, based on energy detection and log-likelihood ratio (LLR) criterion, respectively, are employed for demodulation. Then, the bit error rate (BER) analyses based on pairwise error probability are provided for the proposed DM-OFDM-CPA, and the power ratio between the two groups is optimized to maximize achievable BER performance for a given signal to noise ratio. The simulation results confirm that at a given SE, the proposed DM-OFDM-CPA achieves a significantly better BER performance than the existing OFDM-IM. When the modulation order is lower than 16, it outperforms the classic DM-OFDM. The results also show that two reduced search complexity detectors, especially the LLR detector, provide similar performance to the LC-ML detector in the DM-OFDM-CPA.

Performance of Spread Spectrum Based Multi-Carrier System in Underwater Communication Using Transmitter Pre-Processing

In this paper, we evaluate the bit-error-rate (BER) performance of a turbo-coded, transmitter pre-processing-assisted spread spectrum technology-based multi-carrier (MC) system for the acoustic information transmission in underwater communication. Our primary goal is to improve the power efficiency of the system in terms of signal-to-noise ratio (SNR) while obtaining achievable BER in underwater communication. In underwater communication, inter-symbol-interference and acoustic interference are the two most important issues, which affect the system performance. We use spread spectrum technique to mitigate the effects of unwanted information in the presence of ambient noise. Multi-user transmitter pre-processing (MUTP) is the digital processing method, which is carried out at the transmitter side to offer the low complexity of the receiver. We formulate the singular value decomposition-based pre-processing matrix using noisy feedback of vector quantized (VQ) estimated channel information (CI). We consider the MC communication to mitigate the effects of multi-path propagations. We realize iterative style of decoding algorithm at the receiver to retrieve the acoustic information from the ambient noise contaminated acoustic signals. In particular, we evaluate the error-rate analysis of MC system for realistic channel model based on shallow water channel model, which consists of 11 tap delay. Simulation results emanating from this paper bring to surface the considered coded MC system with MUTP offering a better BER performance with power efficiency regarding SNR while retaining the low complexity of the receiver. Furthermore, we observe that there is an improvement in the system performance when perfect CI is utilized to frame the pre-processing matrix compared with noise contaminated VQ-CI.

Performance of a turbo-coded downlink IDMA system using transmitter pre-processing

In this study, we investigate the bit error rate (BER) performance of a multi-user transmitter pre-processing (MUTP) aided, turbo-coded interleave division multiple access (IDMA) scheme over correlated frequency-selective channels for downlink (DL) communication. We realize MUTP using a zero forcing (ZF) approach. Further, we build the pre-processing matrix using the channel state information of all of the active users. To be specific, we evaluate the BER performance of a coded ZF-MUTP assisted IDMA system for a realistic channel model based on Stanford University Interim channel and Long term Evolution channel specifications; the MUTP is based on both an equal power approach and a maximum-signal-to-noise ratio (MSNR) approach. From our simulation results, we observe that our considered system with a MSNR power allocation regime provides better performance in terms of the achievable BER than the equal power approach, while offering a low complexity receiver for DL transmission.

Multi-user Performance of Relay-Aided MC-CDMA Downlink System Employing Transmitter Preprocessing Based on Feedback of Vector Quantized CSI

The achievable bit-error-rate (BER) performance of a relay-aided downlink (DL) multi-carrier code division multiple access (MC-CDMA) cellular system, where multi-user interference (MUI) and inter-relay interference (IRI) are the dominant channel impairments is investigated in this paper, principally from a transmitter signal processing perspective. Specifically, in this paper, we investigate the considered system by employing three cooperation strategies. The MUI and IRI are mitigated with the aid of the transmitter preprocessing (TP) operated at the base station (BS) and relays, respectively. The TP operated at the BS that suppresses the MUI at the relays is based on the maximum-signal-to-interference-plus-noise ratio approach, while that operated at the relays that mitigates the IRI relies on the classical transmit minimum-mean-square-error principle. Further, the TP in our work is constructed with the aid of vector-quantized channel state information (VQ-CSI) acquired via feedback channels. Our simulation study shows that relay-aided cooperative DL MC-CDMA system employing TP, results in better achievable BER, as the TP helps in achieving the relay-diversity by mitigating the DL-MUI and IRI at the relays and DMSs, respectively. Furthermore, our study demonstrates that the resultant BER performance of the VQ-CSI based TP remains close to that achieved with the perfect CSI based TP. Hence, we advocate that the feedback of the VQ-CSI to the transmitter for conceiving the preprocessing can be considered as an efficient approach, particularly in a frequency division duplex type wireless system.

Field trial over 820 km installed SSMF and its potential Terabit/s superchannel application with up to 57.5-Gbaud DP-QPSK transmission

In this paper, we report the result of a field trial of 56-Gbaud (224-Gbit/s) and 57.5-Gbaud (230-Gbit/s) dual-polarization quadrature phase shift keying (DP-QPSK) coherent optical transmission over 820km installed standard single mode fiber (SSMF). Offline digital signal processing (DSP) was applied for signal recovery and bit-error-rate (BER) counting in our field trial experiments, and BER performance well below the 7% overhead hard-decision forward error correction (FEC) error-free threshold (4.5×10−3) at 231-1 pseudo random bit sequence (PRBS) pattern length has been achieved, with the best achievable BERs of 2×10−4 (56-Gbaud) and 3×10−4 (57.5-Gbaud), respectively. In parallel a 1.15-Tbit/s (5×230-Gbit/s) quasi-Nyquist spaced wavelength division multiplexing (WDM) superchannel transmission over the same 820km optical field link (FL) was also investigated through numerical simulations based on the same 57.5-Gbaud DP-QPSK signal using 1% roll-off Nyquist pulse shaping with 60-GHz channel spacing, and the results indicate that the BER performance well below the 7% overhead hard-decision FEC error-free threshold (4.5×10−3) for the 1.15-Tbit/s DP-QPSK superchannel transmission can be achieved.

Adaptive Nonlinear Equalizer Using a Mixture of Gaussian-Based Online Density Estimator

This paper introduces a new adaptive nonlinear equalizer relying on a radial basis function (RBF) model, which is designed based on the minimum bit error rate (MBER) criterion, in the system setting of the intersymbol interference channel plus cochannel interference (CCI). Our proposed algorithm is referred to as the online mixture of Gaussian-estimator-aided MBER (OMG-MBER) equalizer. Specifically, a mixture of Gaussian-based probability density function (pdf) estimator is used to model the pdf of the decision variable, for which a novel online pdf update algorithm is derived to track the incoming data. With the aid of this novel online mixture of Gaussian-based sample-by-sample updated pdf estimator, our adaptive nonlinear equalizer is capable of updating its equalizer's parameters sample by sample to aim directly at minimizing the RBF nonlinear equalizer's achievable bit error rate (BER). The proposed OMG-MBER equalizer significantly outperforms the existing online nonlinear MBER equalizer, known as the least bit error rate equalizer, in terms of both the convergence speed and the achievable BER, as is confirmed in our simulation study.

MBER Space Time Equalization assisted Multiuser Detection

A novel minimum bit-error rate (MBER) space–time-equalization (STE)-based multiuser detector (MUD) is proposed for multiple-receive-antenna-assisted space-division multiple-access systems. It is shown that the MBER-STE-aided MUD significantly outperforms the standard minimum mean-square error design in terms of the achievable bit-error rate (BER). Adaptive implementations of the MBER STE are considered, and both the block-databased and sample-by-sample adaptive MBER algorithms are proposed. The latter, referred to as the least BER (LBER) algorithm, is compared with the most popular adaptive algorithm, known as the least mean square (LMS) algorithm. It is shown that in case of binary phase-shift keying, the computational complexity of the LBER-STE is about half of that required by the classic LMS-STE. Our simulation results demonstrate that the MBER ST-DFE assisted MUD is more robust to channel estimation errors as well as to potential error propagation imposed by decision feedback errors, compared to the MMSE ST-DFE assisted MUD.