Symbol Error Rate Research Articles

Interference Cancelation for Coexistence of LoRaWAN With Wireless Power Transfer

Low power wide area networks (LPWANs), which realize long-distance communication with low power consumption, are suitable for wireless sensor networks (WSNs). In particular, long range wide area network (LoRaWAN) has been actively studied in recent years. Since wireless power transfer (WPT) charges the battery of terminals by sending high-frequency signals, it can avoid operational disruption for battery replacement and unnecessitate wiring. However, if it is not well designed, WPT may cause interference to other wireless communication systems using the same frequency band. This paper proposes a simple yet effective WPT interference cancellation method, which is suitable for LoRaWAN, to take a step to move the coexistence of LPWAN and WPT forward. The proposed method estimates the initial phase of the interfering signal by utilizing the packet frame structure of LoRaWAN and removes the interfering signal from the received signal during the signal detection process. Computer simulation results show that the proposed method can achieve almost the same symbol error rate (SER) performance as the system without interference, even under WPT interference.

Analysis on the performance of reconfigurable intelligent surface-aided free-space optical link under atmospheric turbulence and pointing errors

<span lang="EN-US">Free-space optical (FSO) communication can provide the cost-efficient, secure, high data-rate communication links required for applications. For example, it provides broadband internet access and backhauling for the fifth-generation (5G) and the sixth-generation (6G) communication networks. However, previous solutions to deal with signal loss caused by obstructions and atmospheric turbulence. In these solutions, reconfigurable intelligent surfaces (RISs) are considered hardware technology to improve the performance of optical wireless communication systems. This study investigates the pointing error effects for RIS-aided FSO links under atmospheric turbulence channels. We analyze the performance of RIS-aided FSO links influenced by pointing errors, atmospheric attenuation, and turbulence for the subcarrier quadrature amplitude modulation (SC-QAM) technique. Atmospheric turbulence is modeled using log-normal distribution for weak atmospheric turbulence. Several numerical outcomes obtained for different transmitter beam waist radius and pointing error displacement standard deviation are shown to quantitatively illustrate the average symbol error rate (ASER).</span>

Analysis on the performance of pointing error effects for RIS-aided FSO link over gamma-gamma channels

In this study, we analysis on the performance of pointing error effects for reconfigurable intelligent surfeces (RISs) aided free-space optical (FSO) communication link over moderate to strong atmospheric turbulence channels. Among these solutions, RISs are considered as hardware technology to improve performance of optical wireless communication systems. Performance evaluation of systems is affected by atmospheric attenuation, pointing errors and moderate to strong atmospheric turbulence channels for quadrature amplitude modulation (QAM) technique. Atmospheric turbulence channel from moderate to strong is modeled using gamma-gamma distribution. Several numerical results obtained the average symbol error rate (ASER) performance versus beam waist radius and signal to noise ratio for three value of pointing error displacement standard deviation. From the results, it is show that with RIS assisted can effectively improve the performance and link distance of the wireless communication systems.

Double RIS-Assisted MIMO Systems Over Spatially Correlated Rician Fading Channels and Finite Scatterers

This paper investigates double RIS-assisted MIMO communication systems over Rician fading channels with finite scatterers, spatial correlation, and the existence of a double-scattering link between the transceiver. First, the statistical information is driven in closed form for the aggregated channels, unveiling various influences of the system and environment on the average channel power gains. Next, we study two active and passive beamforming designs corresponding to two objectives. The first problem maximizes channel capacity by jointly optimizing the active precoding and combining matrices at the transceivers and passive beamforming at the double RISs subject to the transmitting power constraint. In order to tackle the inherently non-convex issue, we propose an efficient alternating optimization algorithm (AO) based on the alternating direction method of multipliers (ADMM). The second problem enhances communication reliability by jointly training the encoder and decoder at the transceivers and the phase shifters at the RISs. Each neural network representing a system entity in an end-to-end learning framework is proposed to minimize the symbol error rate of the detected symbols by controlling the transceiver and the RISs’ phase shifts. Numerical results verify our analysis and demonstrate the superior improvements of phase shift designs to boost system performance.

On the performance of reconfigurable intelligent surface-assisted UAV-to-ground communication systems

In this study, to reduce the average symbol error rate, and improve coverage and reliability of unmanned aerial vehicles (UAVs) to ground communication systems. In this case, we propose a reconfigurable intelligent surfaces (RISs) assisted for UAV to ground communication scheme, where radio frequency (RF) signal generator sends an unmodulated carrier signal from UAVs to the RIS. At reconfigurable intelligent surface, the RIS modulates each signal, and RIS is as a signal generator. We carry out a performance analysis of UAV-to-ground communication systems with RIS-assisted and without RIS for subcarrier quadrature amplitude modulation (SC-QAM) technique. The analytical expressions of average symbol error rare (ASER) and average channel capacity (ACC) is derived. From the results, it is show that with RIS assisted can effectively improve the reliability and coverage of the UAVs to ground communication systems.

A Wireless Channel Equalization Method Based on Hybrid Whale Optimization: For Constant Modulus Blind Equalization System

This paper proposes a wireless channel equalization method applied to the constant modulus blind equalization system, which addresses the slow convergence and strong randomness in the initialization of equalizer weights in the constant modulus blind equalization algorithm (CMA) by introducing a hybrid arithmetic whale optimization algorithm (HAWOA). The mean square error in the CMA is utilized as the cost function for the HAWOA to obtain a more effective initial weights for the equalizer. To validate the superiority of the hybrid arithmetic whale constant modulus blind equalization algorithm, tests are conducted on the equalization system using 16QAM and 64QAM signals. The simulation results demonstrate that the proposed algorithm achieved better initial weights compared to the CMA and the constant modulus blind equalization algorithm based on the whale optimization algorithm. It can obtain the desired mean square error with a lower symbol error rate in fewer iterations. Furthermore, the hybrid arithmetic whale constant modulus blind equalization algorithm exhibited faster convergence in optimizing initial weights, effectively enhancing the equalization performance of the CMA in wireless channels while ensuring timeliness.

A deep reinforcement learning for energy efficient resource allocation Intelligent Reflecting Surface (IRS) driven Non-Orthogonal Multiple Access Beamforming (NOMA-BF)

A deep reinforcement learning for energy efficient resource allocation Intelligent Reflecting Surface (IRS) driven Non-Orthogonal Multiple Access Beamforming (NOMA-BF)

On the performance of energy harvesting‐assisted Nth best relay cooperative networks in Nakagami‐m fading

SummaryWe study the energy harvesting (EH)‐assisted system model based on the performance of a dual‐hop cooperative communication system that is subjected to Nakagami‐ fading. Through the partial relay selection method, the selection of th best relay (BR) is performed among amplify and forward (AF) relays, which can harvest energy from radio frequency signals. At the receiver, the selection combining scheme is considered to select between the signals of th best relaying path and the direct path. For this considered system, we compute the closed‐form expressions of outage probability (OP) and the average symbol error rate (ASER) for higher order quadrature amplitude modulation (QAM) techniques, especially for rectangular QAM, cross QAM, and hexagonal QAM. Further, a new moment‐generating function expression is obtained which is used to derive the ASER expression related to the generalized non‐coherent modulation technique. We also give the asymptotic expression of OP to find out the diversity order. Furthermore, we study the effect of fading parameters, th BR, and other factors on system behavior. Finally, we verify the derived expressions with Monte Carlo simulations.

Constrained Riemannian Noncoherent Constellations for the MIMO Multiple Access Channel

We consider the design of multiuser constellations for a multiple access channel (MAC) with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> users, with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> antennas each, that transmit simultaneously to a receiver equipped with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> antennas through a Rayleigh block-fading channel when no channel state information (CSI) is available to either the transmitter or the receiver. In full-diversity scenarios where the coherence time is at least <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> ≥ ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> + 1) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> , the proposed constellation design criterion is based on the asymptotic expression of the multiuser pairwise error probability (PEP) derived by Brehler and Varanasi (2001). In non-full diversity scenarios, for which the previous PEP expression is no longer valid, the proposed design criteria are based on proxies of the PEP recently proposed by Ngo and Yang (2021). Although both the PEP expression and its bounds or proxies were previously considered intractable for optimization, in this work we derive their respective unconstrained gradients. These gradients are in turn used in the optimization of the proposed cost functions in different Riemannian manifolds representing different power constraints. In particular, in addition to the standard unitary space-time modulation (USTM) leading to optimization on the Grassmann manifold, we consider a more relaxed percodeword power constraint leading to optimization on the so-called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oblique manifold</i> , and an average power constraint leading to optimization on the so-called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">trace manifold</i> . Equipped with these theoretical tools, we design multiuser constellations for the MIMO MAC in full-diversity and non-full-diversity scenarios with state-of-the-art performance in terms of symbol error rate (SER).

Permutation Matrix Modulation

We propose a novel scheme that allows MIMO system to modulate a set of permutation matrices to send more information bits, extending our initial work on the topic. This system is called Permutation Matrix Modulation (PMM). The basic idea is to employ a permutation matrix as a precoder and treat it as a modulated symbol. We continue the evolution of index modulation in MIMO by adopting all-antenna activation and obtaining a set of unique symbols from altering the positions of the antenna transmit power. We provide the analysis of the achievable rate of PMM under Gaussian Mixture Model (GMM) distribution \revv{and finite cardinality input (FCI). Numerical results are evaluated by comparing PMM with the other existing systems.} We also present a way to attain the optimal achievable rate of PMM by solving a maximization problem via interior-point method. A low complexity detection scheme based on zero-forcing (ZF) is proposed, and maximum likelihood (ML) detection is discussed. We demonstrate the trade-off between simulation of the symbol error rate (SER) and the computational complexity where ZF performs worse in the SER simulation but requires much less computational complexity than ML.

Performance Analysis of NOMA-Based Hybrid Satellite-Terrestrial Relay Networks With CCI

Hybrid satellite-terrestrial relay networks (HSTRNs) which exploit relay cooperative technology in the integrated system of satellites and terrestrial base stations (BSs) are expected to offer enhanced transmission performance benefited from the spatial gain of independent fading paths. To enable multi-user accessing and resource sharing among users, non-orthogonal multiple access (NOMA) technique can be applied in HSTRNs. In this paper, we consider a NOMA-based HSTRN where a satellite transmits signals to a relay base station (RBS) and a destination ground station (DGS), and RBS also serves a cellular user (CU) and DGS simultaneously by leveraging NOMA scheme. We assume that the satellite shares spectrum with a number of cellular small BSs (SBSs), hence SBSs will cause co-channel interference (CCI) to DGS, RBS and CU. We examine the transmission characteristics of the satellite and terrestrial links, and derive the closed-form expressions of the outage probability (OP) and average symbol error rate (ASER) of DGS and CU, respectively. Specially, we consider the effect of perfect and imperfect successive interference cancellation (SIC) on the ASER performance of CU. Then, considering the stochastic characteristics of satellite links and CCI, we analyze the mean energy efficiency (MEE) of the satellite and propose an optimal power allocation scheme which maximizes the MEE of the satellite and achieves system performance optimization. Simulation results demonstrate the effectiveness of the theoretical analysis and the proposed power allocation scheme.

Secure Linear Precoding in Overloaded MU-MIMO Wireless Networks

We investigate signaling and linear precoding designs for secure downlink communications in a multiuser MIMO (MU-MIMO) network. The network is tapped by an external eavesdropper (Eve) who is equipped with a large number of antennas. In addition to the transmission of several (unicast) information signals to downlink users (Bobs), the transmitter (Alice) generates friendly jamming (FJ), aiming to prevent Eve from decoding Alice’s signals. To mitigate both multiuser interference (MUI) and FJ on Bobs, MU-MIMO systems often rely on zero-forcing (ZF) precoders. A condition for the application of such precoders is that the network must be <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">underloaded</i> , i.e., Alice has more antennas than all Bobs combined. For <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">overloaded</i> scenarios, ZF-based precoding cannot guarantee nullification of both MUI and FJ at legitimate receivers. Accordingly, we propose a combined signaling-and-precoding scheme that can also be applied to an overloaded MU-MIMO network. In an underloaded scenario, our technique is shown to impose a more stringent antenna requirement on Eve than a classical ZF-based precoding, i.e., Eve must utilize more antennas if she is to successfully eavesdrop on Alice’s transmissions. Although our scheme is comparable to antenna selection (AS) approaches in terms of Eve’s antenna requirement, it incurs much less delay and complexity by avoiding frequent on/off switching of the RF chains at Bobs. For underloaded scenarios, we provide security analysis that establishes the conditions under which our scheme is superior to the ZF scheme. Using computer simulations, we validate the advantages of our design and contrast it with ZF and AS schemes in terms of the symbol error rate, the EVM, and the achievable rate in both underloaded and overloaded scenarios.

순환형-하다마드 코드로 직교 변조된 위성항법 보강 신호의 FFT 기반 심볼 복조 기법

In this paper, a fast Fourier transform (FFT)-based symbol demodulation method is proposed for a satellite navigation augmentation signal orthogonally modulated using Cyclic-Hadamard code. The proposed method rearranges the code and performs zero-padding interpolation to enable discrete Fourier transform computation by using the radix-2 FFT algorithm. The proposed method was compared with a correlation receiver in terms of symbol demodulation performance and receiver implementation complexity. Simulation results revealed that the proposed method achieves the same symbol error rate as the correlation receiver while reducing the computational complexity required at higher data rates.

Semi-Blind Receivers for Two-Hop MIMO Relay Systems with a Combined TSTF-MSMKron Coding.

Due to the increase in the number of mobile stations in recent years, cooperative relaying systems have emerged as a promising technique for improving the quality of fifth-generation (5G) wireless networks with an extension of the coverage area. In this paper, we propose a two-hop orthogonal frequency division multiplexing and code-division multiple-access (OFDM-CDMA) multiple-input multiple-output (MIMO) relay system, which combines, both at the source and relay nodes, a tensor space-time-frequency (TSTF) coding with a multiple symbol matrices Kronecker product (MSMKron), called TSTF-MSMKron coding, aiming to increase the diversity gain. It is first established that the signals received at the relay and the destination satisfy generalized Tucker models whose core tensors are the coding tensors. Assuming the coding tensors are known at both nodes, tensor models are exploited to derive two semi-blind receivers, composed of two steps, to jointly estimate symbol matrices and individual channels. Necessary conditions for parameter identifiability with each receiver are established. Extensive Monte Carlo simulation results are provided to show the impact of design parameters on the symbol error rate (SER) performance, using the zero-forcing (ZF) receiver. Next, Monte Carlo simulations illustrate the effectiveness of the proposed TSTF-MSMKron coding and semi-blind receivers, highlighting the benefit of exploiting the new coding to increase the diversity gain.

C-FD MAC: Constellation based Full-Duplex MAC protocol

Simultaneous transmission and reception of data packets in Full-Duplex (FD) communication can theoretically double the system throughput. However, efficient self-interference mitigation and symbol detection at the receiver is required to realize the full potential of FD communication in practical scenarios. In this paper, we propose a constellation-based FD medium access control (MAC) protocol (C-FD) for wireless local area networks (WLAN). In the proposed C-FD MAC protocol, the node and Access Point (AP) can exchange packets simultaneously by transmitting the symbols and using different modulation schemes. The superimposed constellation diagram has been used to decode the symbols efficiently at both ends. The novel feature of the C-FD MAC protocol is that it does not require any complicated interference cancellation techniques. The analytical results for Symbol Error Rate (SER), Packet Error Rate (PER), and throughput have been derived for the symmetrical and asymmetrical FD link considering the additive white Gaussian noise (AWGN) with Rayleigh fading. The proposed C-FD MAC protocol achieves nearly twice the throughput compared to Half duplex (HD) communication without compromising the SER. The analytical results have been validated with extensive simulation.

QoE-aware NOMA user grouping in 5G mobile communications using a multi-stage interval type-2 fuzzy set model

The user grouping has a significant impact on the performance of non-orthogonal multiple access (NOMA) systems. The present work is focused on downlink NOMA user grouping leveraging the type-2 fuzzy set (T2FS). The main drawback of conventional user grouping methods is low efficiency for middle users which degrades the overall system performance. To overcome this problem, a 2-step user grouping process is proposed that includes identifying group candidates and selecting the most qualified one. The first step is handled by introducing a group membership competency criterion based on T2FS modeling due to its capability to handle extra uncertainty in real-world phenomena. The second step involves adding the most qualified candidate to the desired group, given the additional power imposed on the group. The key contribution of the paper is twofold: (i) it affords a multi-stage structure to evaluate the competency of users to join a particular group relying on T2FS modeling. It allows groups of different sizes to be formed, depending on the network channel status and quality of experience (QoE) requirements, and (ii) the additional power imposed on the group is exploited as a measure to select the final group. In this regard, the analysis of interference that each user brings to others in the same group is taken into account. The performance of the proposed scheme is evaluated by simulations and compared with other methods. The obtained results indicate the efficiency of the proposed approach in terms of total power consumption and symbol error rate.

Orthogonal frequency division multiplexing technology based on MATLAB

The subcarriers of an orthogonal frequency division multiplexing (OFDM) system are not identical in the time domain, and their spectra also overlap. As a result, the spectrum is being used effectively. Its effective use of frequency resources and capacity to combat channel fading have made it the de facto technical standard. In wireless communication, numerous pathways in the channel can lead to interference between symbols, known as inter-symbol interference (ISI). This research supplements OFDM systems with some safeguards to eliminate inter-symbol interference. Most traditionally, OFDM symbols have had their post-event sample points duplicated to their beginnings, a process known as Cyclic prefix (CP) padding in the protection interval. In order to further counteract ISI, a protection interval might be added to the beginning of each symbol. An OFDM system's bit error rate (BER) can be decreased by using cyclic prefixes to attenuate inter-code interference. This study explains how OFDM and CP-OFDM work and compares their performance. The primary topic of this study is a contrast between OFDM and CP-OFDM concerning the performance metrics of average symbol error rate (BER) and signal spectrum diagram (PSD).

Multihop IRS-assisted free space optics communication with DF relaying: a performance analysis.

Free space optics communication (FSO) offers several advantages over its counterpart radio frequency (RF) systems in terms of bandwidth, data rates, and cost efficiency. However, FSO, being a line-of-sight (LoS) communication system, is hindered by various environmental factors. In this paper, we propose a multihop decode-and-forward (DF) relaying-based intelligent reflecting surface (IRS)-assisted FSO system with an aim to deal with the impediments in FSO communication, and it is assumed that each IRS consists of multiple reflecting elements. Specifically, we derive end-to-end expressions for cumulative distribution function (CDF) of output instantaneous signal-to-noise ratio (SNR). Furthermore, with the aid of the CDF statistics, we study the performance of the proposed system by obtaining the expressions for outage probability (OP) and average symbol error rate (ASER) in terms of multivariate Fox's H-function. Moreover, we have quantified the system performance by numerical results. The numerical results show that the multihop IRS-assisted FSO system provides better performance when compared to a single-hop IRS-assisted FSO system and multihop FSO system without IRS. Finally, the derived expressions of OP and ASER are validated using Monte-Carlo simulations.

Initialized autoencoders to find constellations robust to residual laser phase noise

Autoencoder (AE) has been used to find quadrature amplitude modulation (QAM) constellations robust to optical impairments, such as residual laser phase noise or fiber nonlinearities. We examine AE for constellations for fiber links with residual phase noise following phase recovery. We study 1) improved constellations via AE neural network (NN) initialization, 2) bit-to-symbol mappings for AE constellations, and 3) performance enhancement from the AE decoder as a detection algorithm. We compare our performance to several other phase-noise-optimized constellations, using an identical phase recovery method for fair comparison. We confirm the improved performance of our constellations experimentally as well as via simulation. Our AE initialization technique (using previous constellations found experimentally, empirically, numerically, etc.) is shown to improve constellations for 16QAM and 64QAM. A bit-to-symbol mapping is essential to benefit fully from AE constellations, but is intractable to optimize. We use an ad hoc approach that derives mappings from our initialization constellations. Our AE initialization technique leads to performance improvements over the previous QAM constellations under all metrics: generalized mutual information (GMI), bit error rate (BER) and symbol error rate (SER). We examine the gap between BER and SER due to non-optimal bit-to-symbol mappings. The AE approach to constellation design has as a byproduct an optimized detector: the AE decoder. We quantify the improvement of this detector over the classic maximum likelihood detection that neglects phase noise.

High-Performance Soft Decision Decoding for Compound Channel Using RS-SPC Concatenated Codes

A novel single parity check-assisted ordered statistic decoding (SPC-OSD) algorithm for the compound channel is proposed for Reed-Solomon (RS) codes. The algorithm can effectively use the channel soft information to accurately determine the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N - K</i> unreliable symbol positions to be erased by using single parity checking and threshold comparison. Besides that, the second-burst error symbol is also proposed as a supplement to unreliable symbols. Based on these predetermined errors, the algorithm can be dynamically adjusted according to the channel environment to achieve the best decoding performance. Compared with burst-error correcting algorithm-based ordered-statistics decoding (BC-OSD) and burst error correcting hard-decision decoding-based low-complexity chase algorithm (BCHDD-LCC), simulation results show that the proposed algorithm can give a coding gain reaching up to 2.0dB and 2.1dB respectively, when symbol error rate (SER) is 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> .