Error Performance Of System Research Articles

Fast-OFDM With Index Modulation for NB-IoT

In this letter, a hybrid orthogonal frequency-division multiplexing (OFDM)-based modulation technique for narrowband Internet of Things (NB-IoT) is introduced and analyzed. The technique combines fast-OFDM with index modulation in order to maximize bandwidth and power efficiency for IoT applications. The ideal number of active subcarriers to maximize spectral efficiency is derived. The one-dimensional constellation used in fast-OFDM is also optimized to enhance error performance of the proposed system. Numerical results indicate that the proposed system outperforms other OFDM systems based on index modulation in the relatively low signal-to-noise ratio (SNR) region, while it provides additional design options for trading off power efficiency and spectral efficiency in the higher SNR region.

Error analysis of dual-hop DF relayed underlay cognitive networks over EGK fading channels

In the presented work, we analyze an underlay cognitive relay network, with a decode and forward relay, for its error performance. The channel is modelled on extended generalized-K fading statistics. Interference temperature here is taken as a constraint which puts a limit on the secondary network transmit powers at the source and the relay. This is to ensure that the interference with the primary communication is kept to a minimum which is a mandatory condition for an underlay system. For the system under consideration, the computation of signal-to-noise ratio, respectively at the secondary relay and the destination, is the first step in our analysis. This is followed by the computation of the equivalent cumulative distribution functions. These quantities are then used for the calculation of the analytic expression for the probability of error of the dual-hop underlay system. Our results demonstrate how the error performance depends on different system parameters when working under the mentioned system constraints. Various numerical examples in the end illustrate how these parameters affect the system error performance of the relayed dual-hop underlay cognitive radio network.

Performance analysis of repeated index modulation for OFDM with MRC and SC diversity under imperfect CSI

In this paper, we conduct the investigation into the performance of repeated index modulation-orthogonal frequency division multiplexing (RIM-OFDM) system with spatial diversity comprising the maximal ratio combining (MRC) and selection combining (SC). The considered systems, abbreviated as RIM-OFDM-MRC and RIM-OFDM-SC, are successful in exploiting both the frequency and spatial diversities to provide improvement in the error performance of the conventional IM-OFDM system with diversity reception. We find out the closed-form expressions for the index and symbol error probabilities of RIM-OFDM-MRC and RIM-OFDM-SC under a variety of different channel conditions. We also carry out asymptotic analysis in order to examine the system behavior under influences of system parameters and the imperfection in channel state information (CSI). Performance evaluation through both theoretical and simulation results demonstrates the significant performance improvement of our systems in comparison with the conventional IM-OFDM using MRC/SC even when channel estimation errors occur at the receiver.

Pulse Position-Based Spatial Modulation for Molecular Communications

Multiple-input-multiple-output (MIMO) approaches have been recently introduced to molecular communications (MC) in order to increase the communication throughput. For MIMO systems, index modulation (IM) suggests encoding information bits using the indices of the available antennas, rather than employing spatial multiplexing or performing other space-time coding schemes. Recent works have shown that utilizing the available MIMO antennas with the IM-based approaches improve the error performance of a molecular MIMO system, courtesy of molecular-IM’s robustness against inter-symbol interference and inter-link interference (ILI). Inspired by IM’s prospects on the MC, this letter proposes a novel family of the IM-based schemes to the MC realm. The proposed schemes combine position-based constellations with antenna indices to encode bits in and yield reliable error performances due to their robustness against the ILI.

Afterpulsing effects in SPAD-based photon-counting communication system

Afterpulsing is a critical non-ideal factor of SPAD at telecommunication wavelength, which limits its performance. In order to evaluate the effects of afterpulsing, a new bit error rate (BER) model of SPAD-based photon-counting communication system including afterpulsing is built. To verify the theoretical model, an experimental system is founded. Compared with experimental results, the new BER model is found to be in good agreement. Based on the new BER model, the error performance of photon-counting communication system is investigated. The results indicate that maintaining the afterpulsing probability (AP) of 0, 0.1 will bring 1.2 to 3-dB sensitivity benefit than AP of 0.25. Maintaining the total number of gates per bit above 20 can significantly improve the system sensitivity or background tolerance. Inhibiting the AP below 0.1 is critical for expanding the scale of SPADs array to enhance system error performance.

Bit-error rate investigation of satellite-to-ground downlink optical communication employing spatial diversity and modulation techniques

In this paper, the error performance of multiple apertures receiver system under different modulation schemes is evaluated for satellite-to-ground downlink optical communications. Gamma–Gamma channel model is used for the consideration of moderate to strong atmospheric turbulence. Error rate expression equations of maximum ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) techniques are derived for M-ary pulse position modulation (M-PPM) and M-ary differential PPM (M-DPPM) modulation schemes. Bit-error rate (BER) performances of M-PPM and M-DPPM modulated MRC, EGC, and SC direct detection receiver systems are compared with a single monolithic aperture receiver system. Performances of downlink direct detection multiple apertures receiver system are also compared among on–off keying (OOK), M-PPM, and M-DPPM modulation schemes. Numerical calculations and Monte Carlo (MC) simulations are used to exam the results of our analysis. It is found that, for M-PPM and M-DPPM, the effect of atmospheric turbulence can be reduced by MRC and EGC receiver system, and SC receiver system can show its advantages compared to a single aperture receiver system in the case of large zenith angles. The downlink BER performances of OOK, 8-PPM, and 8-DPPM multiple apertures receiver system are decreased according to the order of 8-PPM, 8-DPPM, and OOK.

Bit-error Rate Analysis of Coherent Detection Equal Gain Combining Spatial Diversity Receivers for Satellite-to-Ground Downlink Optical Transmissions

In this paper, the error performance of coherent detection multiple apertures receiver system is evaluated for satellite-to-ground downlink optical communications. Bit-error rate (BER) expressions of equal gain combining (EGC) receiver system are given for binary phase-shift keying (BPSK) modulation schemes under Gamma-Gamma channel model atmospheric turbulence. Monte Carlo (MC) simulations are used to analyze the BER performance for different number of apertures with the same total aperture area. It is found that coherent detection multiple apertures receiver system can greatly improve the system performance for EGC diversity, but the improved rate of diversity gain decreases with the increase of diversity branches.

Error performance of hybrid wireless-power line communication system

This paper considers a hybrid wireless-power line communication system for smart meter and grid interaction. The performance of the considered system is evaluated for different switching schemes such as threshold based switching, random switching, and selection combining. The power line channel is characterized using the log-normal random variable, whereas the channel response for the wireless link is modeled as the Nakagami-m distributed random variable. The expressions for average bit-error-rate (BER) for the considered switching/combining schemes are obtained, and the average BER performances of all the considered combining schemes are compared. The results are verified through simulations.

Error performance analysis of a non-ideal photon counting array receiver system for optical wireless communication.

In order to detect weak light from background radiation, utilizing an array of Geiger-mode avalanche photodiodes (GM-APDs) as a detector in the receiver is researched. First, the principle of a GM-APD operated in gated mode is analyzed. Based on the Poisson random process of arrival of photons, the trigger probability of a single GM-APD has been computed. Then, according to the trigger probability, a new bit error rate (BER) model of a photon-counting array receiver system is built, and the expression of BER is derived based on the quantum efficiency, signal photons, background photons, dark carriers, and the number of GM-APDs in array. Using the BER expression, the error performance of a new photon-counting array receiver system can be predicted rapidly. Furthermore, the error performance of a system based on an array of GM-APDs is investigated. The simulation results indicated that maintaining the ratio of signal photons and background photons above 1 is necessary for system operation. When background noise is limited to the acceptable range, maintaining a certain scale of GM-APDs (above 20) in array can greatly reduce the demand of transmitting power. Compared with achieving target BERs of 10-6 and 10-9, preserving a BER of 10-3 and making use of error correction coding can further improve the receiving sensitivity to 5-8dB.

A Unified Precoding Scheme for Generalized Spatial Modulation

Generalized spatial modulation (GSM) activates $n_{t}$ out of $N_{t}~(1 \leq n_{t} available transmit antennas, and information is conveyed through $n_{t}$ modulated symbols as well as the index of the $n_{t}$ activated antennas. GSM strikes an attractive tradeoff between spectrum efficiency and energy efficiency. Linear precoding that exploits channel state information at the transmitter enhances the system error performance. For GSM with $n_{t}=1$ (the traditional SM), the existing precoding methods suffer from high computational complexity. On the other hand, GSM precoding for $n_{t} \geq 2$ is not thoroughly investigated in the open literature. In this paper, we develop a unified precoding design for GSM systems, which universally works for all $n_{t}$ values. Based on the maximum minimum Euclidean distance criterion, we find that the precoding design can be formulated as a large-scale nonconvex quadratically constrained quadratic program problem. Then, we transform this challenging problem into a sequence of unconstrained subproblems by leveraging augmented Lagrangian and dual ascent techniques. These subproblems can be solved in an iterative manner efficiently. Numerical results show that the proposed method can substantially improve the system error performance relative to the GSM without precoding and features extremely fast convergence rate with a very low computational complexity.

Trellis code‐aided high‐rate M‐QAM space‐time labeling diversity using a unitary expansion

SummaryIn this paper, we present a high‐rate M‐ary quadrature amplitude modulation (M‐QAM) space‐time labeling diversity (STLD) system that retains the robust error performance of the conventional STLD system. The high‐rate STLD is realised by expanding the conventional STLD via a unitary matrix transformation. Robust error performance of the high‐rate STLD is achieved by incorporating trellis coding into the mapping of additional bits to high‐rate codes. The comparison of spectral efficiency between the proposed trellis code‐aided high‐rate STLD (TC‐STLD) and the conventional STLD shows that TC‐STLD with 16‐QAM and 64‐QAM respectively achieves a 12.5% and 8.3% increase in spectral efficiency for each additional bit sent with the transmitted high‐rate codeword. Moreover, we derive an analytical bound to predict the average bit error probability performance of TC‐STLD over Rayleigh frequency‐flat fading channels. The analytical results are verified by Monte Carlo simulation results, which show that the derived analytical bounds closely predict the average bit error probability performance at high signal‐to‐noise ratios (SNR). Simulation results also show that TC‐STLD with 1 additional bit achieves an insignificant SNR gain of approximately 0.05 dB over the conventional STLD, while TC‐STLD with 2 additional bits achieves an SNR gain of approximately 0.12 dB.

Performance analysis of energy harvesting DF relay system in generalized-[formula omitted] fading environment

The performance of decode-and-forward (DF) relaying systems is analyzed for the energy constrained relay and Generalized-K fading environment, assuming that the communication in both links of relaying system is corrupted by effects of multipath fading and shadowing. We analyze the ergodic and outage capacities for two representative cases: in one case energy harvesting and information transmission are arranged based on time-switching relaying protocol, while in the other analyzed case they are arranged based on power-splitting relaying protocol. The novel analytical closed-form results for error performance of DF energy harvesting system are applicable for wide range of modulation formats. The derived closed-form capacity and error rate expressions are valid for both relaying protocols and various scenarios of composite fading environment. Analytical results are corroborated by an independent simulation method. Finally, the impact of the system and channel parameters on the system performance is demonstrated through numerical analysis.

Research on Adaptive Resource Allocation of Indoor MIMO-OFDM Visible Light Communication System

In this paper, the performance of three typical resource allocation schemes is analyzed, which are applied to indoor MIMO-OFDM visible-light communication system, the maximum capacity allocation algorithm, the rate proportional algorithm and the multi-user subcarrier ordering allocation algorithm. The result of simulation shows that the three algorithms above can effectively improve the performance of indoor MIMO-OFDM visible light communication system. The system is capacity is at least 3 times higher. Simultaneously, in the system capacity, error performance and fairness, these three allocation method are significantly different.

Design and Analysis of Passband Transmitted Reference Pulse Cluster UWB Systems in the Presence of Phase Noise

Transmitted reference pulse cluster (TRPC) signaling was recently proposed and developed for noncoherent ultra-wideband (UWB) communications. In this paper, a practical passband TRPC-UWB system is designed and analyzed to deal with the carrier frequency offset, phase offset and phase noise inherent in voltage-controlled oscillators (VCO) of the transmitter and the receiver. Based on a general model of noisy VCO and employing some reasonable assumptions, an equivalent linear time-invariant (LTI) analytical model is obtained to facilitate the bit error rate (BER) analysis. Our analysis shows that the constant carrier frequency offset and the phase offset can be removed by employing the passband transmitter and the noncoherent receiver. Furthermore, a semi-analytical BER expression is derived to show the impact of phase noise on the system error performance. Simulation results validate the semi-analytical expressions and both of them indicate that TRPC is more robust to the effect of phase noise than conventional transmitted reference (TR) and coherent UWB Rake receivers.

Zero-Forcing Beamforming With Signal Space Diversity

We integrate zero-forcing beamforming (ZFBF) with signal space diversity (SSD) and investigate its performance. The beamforming is applied at the transmitter assuming a closed-loop scenario. First, a dual-stream transmission scheme with $M$ $(M\geq 2)$ transmit and two receive antennas is studied. Then, a generalization for any number of simultaneous substreams is established based on the previous results. A statistical analysis of the proposed scheme is provided and an exact closed-form expression on the average bit error probability is derived. We also present a high signal-to-noise ratio analysis for gaining further insight into diversity level and coding gain of the proposed system. It is shown that the error performance of a ZFBF system can be improved by making use of SSD with only a negligible increase in complexity and no extra use of bandwidth/time resources.

Unified Power Allocation for Receive Spatial Modulation Based on Approximate Optimization

In this paper, a novel unified power allocation (PA) framework is proposed for receive (pre-coding aided) spatial modulation (RSM). We find that the PA matrix design can be formulated as a non-convex quadratically constrained quadratic program (QCQP) problem, whose solution is generally intractable. To tackle this problem, we propose a pair of solvers having different trade-offs in terms of bit-error-rate and complexity. Specifically, we first propose a successive convex approximation (SCA) method, to convert the non-convex QCQP problem under consideration into a series of linear convex subproblems, where the latter can be easily solved by the classic polynomial-time-based optimization method, i.e., the interior point method. To further reduce the computational complexity, we propose an augmented Lagrangian multiplier (ALM) method, which transforms the challenging non-convex constrained PA optimization problem into its unconstrained counterpart, which can be efficiently solved by an iterative manner. Our simulation results show that both the proposed SCA and ALM methods are capable of substantially improving the system error performance compared with the conventional RSM system without PA as well as conventional PA-aided RSM schemes.

Convex Optimization of Distributed Cooperative Detection in Multi-Receiver Molecular Communication

In this paper, the error performance achieved by cooperative detection among K distributed receivers in a diffusion-based molecular communication (MC) system is analyzed and optimized. In this system, the receivers first make local hard decisions on the transmitted symbol and then report these decisions to a fusion center (FC). The FC combines the local hard decisions to make a global decision using an N-out-of-K fusion rule. Two reporting scenarios, namely, perfect reporting and noisy reporting, are considered. Closed-form expressions are derived for the expected global error probability of the system for both reporting scenarios. New approximated expressions are also derived for the expected error probability. Convex constraints are then found to make the approximated expressions jointly convex with respect to the decision thresholds at the receivers and the FC. Based on such constraints, suboptimal convex optimization problems are formulated and solved to determine the optimal decision thresholds which minimize the expected error probability of the system. Numerical and simulation results reveal that the system error performance is greatly improved by combining the detection information of distributed receivers. They also reveal that the solutions to the formulated suboptimal convex optimization problems achieve near-optimal global error performance.

Performance analysis of decode-and-forward dual-hop optical spatial modulation with diversity combiner over atmospheric turbulence

Dual-hops transmission is a growing interest technique that can be used to mitigate against atmospheric turbulence along the Free Space Optical (FSO) communication links. This paper analyzes the performance of Decode-and-Forward (DF) dual-hops FSO systems in-conjunction with spatial modulation and diversity combiners over a Gamma–Gamma atmospheric turbulence channel using heterodyne detection. Maximum Ratio Combiner (MRC), Equal Gain Combiner (EGC) and Selection Combiner (SC) are considered at the relay and destination as mitigation tools to improve the system error performance. Power series expansion of modified Bessel function is used to derive the closed form expression for the end-to-end Average Pairwise Error Probability (APEP) expressions for each of the combiners under study and a tight upper bound on the Average Bit Error Rate (ABER) per hop is given. Thus, the overall end-to-end ABER for the dual-hops FSO system is then evaluated. The numerical results depicted that dual-hops transmission systems outperformed the direct link systems. Moreover, the impact of having the same and different combiners at the relay and destination are also presented. The results also confirm that the combination of dual hops transmission with spatial modulation and diversity combiner significantly improves the systems error rate with the MRC combiner offering an optimal performance with respect to variation in atmospheric turbulence, change in links average received SNR and link range of the system.

Optical Spatial Modulation with Diversity Combiner in Dual-Hops Amplify-and-Forward Relay Systems Over Atmospheric Impairments

In this paper, we analyzed a dual-hop optical spatial modulation channel state information-assisted amplified and forward (AF) relay system with spatial diversity combiner under the influence of gamma-gamma atmospheric turbulence induced fading and pointing error impairments. Maximum ratio combiner (MRC) and equal gain combiner (EGC) with heterodyne detection are considered at the destination as mitigation tools to improve the system error performance. The statistical characteristics of AF relay in terms of moment generating function (MGF), probability density function and cumulative density function are derived for both impairments. Based on these expressions, the average pairwise error probability for each of the combiners under study is determined and the average bit error rate (ABER) for the system is given by using union bounding technique. By utilizing the derived ABER expressions, the effective capacity for the considered system is then obtained. The effect of turbulence strength ranging from weak to strong levels and pointing errors in terms of beam width and jitter displacement are studied. The numerical results obtained show that the more the turbulence strength and/or pointing error increases, the more the error rate and effective capacity of the system deteriorates. Under the same conditions, the results confirmed that MRC system offers an optimal performance compared with EGC.

SNR and transmission error rate for remote laser communication system in real atmosphere channel

Performance of remote laser communication system fluctuates greatly due to influence by atmospheric turbulence, it is difficult to assess its system error performance effectively. On the basis of the atmospheric attenuation channel and atmospheric turbulence channel, this paper establishes the integrated computation signal-to-noise ratio(SNR) function and transmission error rate function under the condition of atmospheric attenuation and the atmospheric turbulence, analyzes the affecting factors of the transmission error rate under two kinds of channel in remote transmission, calculates the relation between atmospheric attenuation coefficient and haze particle size under different visibility in atmospheric attenuation channel, as well as the relationship between the optimal threshold and intensity fluctuation under different transmitting powers in atmospheric turbulence channel. Through the test in atmospheric turbulence channel, results show that light intensity fluctuation is the main factor causing low system performance within a certain range of background noise, the new calculation method of SNR makes the variation between the actual system bit error rate and the achievable minimum bit error rate in theory several orders of magnitude. The models can effectively assess the performance of laser communication system under atmospheric attenuation and atmospheric turbulence, and provide a reference for relevant researches.