BER Performance Research Articles

Design and analysis of an OFDM-based orthogonal multilevel code-shifted differential chaos shift keying

In this paper, a new non-coherent <span class="il">chaos</span>-<span class="il">based</span> communication that combined <span class="il">Orthogonal</span> <span class="il">Multilevel</span> <span class="il">Code</span>-<span class="il">Shifted</span> <span class="il">Differential</span> <span class="il">Chaos</span> <span class="il">Shift</span> <span class="il">Keying</span> with <span class="il">orthogonal</span> frequency division multiplexing named (<span class="il">OFDM</span>-OMCS-DCSK) modulation system. New <span class="il">orthogonal</span> chaotic signal sets are generated by hybrid Gram-Schmidt algorithm <span class="il">and</span> Walsh <span class="il">code</span> function <span class="il">and</span> used it to carry high data rate in the same time slot. The Bandwidth efficiency <span class="il">of</span> the <span class="il">OFDM</span>-OMCS-DCSK system is comparing with conventional system. Also, the BER analytic expressions are derived under (AWGN) <span class="il">and</span> multipath Rayleigh fading channels <span class="il">and</span> comparing with the simulation results. Furthermore, the BER performance is compared with <span class="il">OFDM</span>-DCSK to found that the proposed system has the best BER performance with high data rate feature.

Regularized Block Diagonalization Precoding Transmission Scheme Using Relay in NOMA

In Multiuser Multiple Input Multiple Output (MU-MIMO) system, Block Diagonalization (BD) and Regularized Block Diagonalization (RBD) are schemes which completely suppress Inter-User Interference (IUI). BD and RBD use the same number of RF chains and transmit antennas as the number of data streams in general. This paper proposes a RBD precoding transmission scheme using relay in Non-orthogonal Multiple Access (NOMA) system to reduce complexity of transmitter structure. The proposed scheme uses only half the number of RF chains and transmit antennas compared to the conventional RBD scheme. The number of Singular Value Decomposition (SVD) of the proposed scheme is also reduced compared to the conventional RBD, while Successive Interference Cancellation (SIC) is needed additionally. However, the proposed algorithm can achieve low computational complexity since SIC is simpler than SVD. However, the proposed scheme has poor BER performance compared to the conventional RBD. Therefore, further study is needed to increase the BER performance while the complexity is reduced.

Analysis of WOFDM over LTE 1.25 MHz Band

Orthogonal Frequency Division Multiplexing (OFDM) is the one of the most preferred multiplexing technique for realizing high-speed wireless communication, like Long Term Evolution (LTE) and LTE-Adv. In the era of digital wireless communication, applications of wavelet theory have been favorably applied in many areas of signal processing. Orthogonality, flexible time-frequency analysis, and the ability to characterize signals accurately have attracted the attention of the telecommunication community to use wavelet as a basis function for OFDM. In this paper, discrete wavelet transform (DWT) has been proposed as an alternative signal analysis with multiple merits such as support high-speed applications, immune to distortion, wavelet diversity, better error performance, and efficient bandwidth utilization. A simulative analysis of various wavelets, at different modulation techniques, over OFDM has been presented to demonstrate the improvement in BER performance. Further, in accordance with the LTE parameterization over 1.25 MHz band, the performance of wavelet-based OFDM (WOFDM) is found significantly higher in terms of maximum achievable data rate and system spectral efficiency.

Turbo codes for telemedicine applications

Telemedicine is an emerging technology in the area of remote medical services. It involves real-time communication between patients and healthcare providers through electronic equipment for diagnosing diseases. Biomedical signal processing is the process of measurement and analysis to deliver required information for doctors to make decisions. The identification of diseases is made upon collecting the biomedical signals from the patient’s body. Telemedicine concepts can be employed for this method. For remote diagnosis purposes, as the biomedical signal needs to transmitted through wireless media there is a need for efficiently coding them. In this paper, turbo coding is used and is transmitted through the AWGN channel. The performance of BER for different turbo decoding algorithms are compared to obtain error free transmission.

Novel Hybrid MIMO Detector for Spatial Multiplexed MIMO System

The need of data transmission has recently increased dramatically and the promising MIMO technology has been employed to preserve reliability. It can achieve exceptionally enhanced spectral proficiencies by adopting several antennas both at the source and the receiver. However, complexity of several detection schemes escalates because of tremendous increasing of customers and antennas. This paper proposes novel hybrid MIMO detection (NHMD) method to compromise the complexity and the hardware design challenges. The key objective is to develop a less-complex hybrid detection system to enhance hardware execution suitability without negotiating the performance of the bit error rate. The proposed NHMD method combines conventional linear detectors such as zero-force (ZF) and minimum mean square error (MMSE) with the K-best detector for quality enhancement. It introduces an optimal differential evolution (ODE) algorithm that selects detector using multiple constraints. Moreover, this method uses parallelism process to reduce the number of arithmetic logics. The proposed NHMD method has been done for different antenna configurations (2×2, 4×4) and implemented on Xilinx tool with different FPGA families. The simulation results confirm that NHMD method consumes less hardware’s, power and higher throughput without affecting BER performance.

Investigation on the BER performance of downlink JT-CoMP-NOMA with different modulation schemes

The principle of joint transmission coordinated multipoint with non-orthogonal multiple access (JT-CoMP-NOMA) is to allow multiple cells in the network to cooperatively transmit data to users using the same network resources in frequency and time domains. The approach would be beneficial in enhancing the system performance in the context of spectral efficiency. This paper presents the performance comparison of JT-CoMP-NOMA for several modulation schemes including QPSK, 16-QAM and 64 QAM in downlink transmission in the context of bit error rate. We conduct an investigation to compare the error performance of JT-CoMP-NOMA with NOMA system. Our simulation results demonstrate that the JT-CoMP-NOMA provides lower bit error rate compared to NOMA system.

Reduced OoB Emission and PAPR Using Partial-OSLM technique in 5G UFMC Systems

Universal-filtered multi-carrier (UFMC) waveformis considered as a potential candidate for next generation wirelesssystems due to its robustness against inter-carrier interference(ICI) and the low latency required in 5G systems. In this paper, apulse shaping approaches in UFMC technique is studied to reducethe spectral leakage into nearby sub-bands. The performance ofvarious types of window functions such as Chebychev, Hamming,Hanning and Blackman with UFMC are compared. This leadsto different coefficients and attenuation shapes, that enabledto choose the proper window function. Finally, a new selectivemapping (SLM) peak to average power ratio (PAPR) reductiontechnique is proposed to enhance the UFMC system performance.Results show that the BER performance of UFMC with allwindows functions are the same. However, Blackman windowfunction has a higher attenuation for sidebands compared withothers.

Two Dimensional Adaptive Multichannel Decision Feedback Equalization for OTFS System

Orthogonal time-frequency-space (OTFS) modulation has shown significant error performance advantages over orthogonal frequency division multiplexing (OFDM) in time-varying channels. However, the symbols in OTFS frames still suffer from inter-Doppler interference (IDI) and inter-symbol interference (ISI). In this letter, we propose a two dimensional (2D) adaptive multichannel decision feedback equalizer (DFE) to combat the interference. The proposed receiver constructs the input signal and feedback signal of the DFE based on the characteristic of OTFS modulation. Meanwhile, by exploiting the sparsity feature of the channels in delay-Doppler domain, the iterative improved proportionate normalized least mean squares (IPNLMS) algorithm is employed to achieve fast convergence and fast tracking. The simulation results show that the proposed equalizer could achieve satisfied BER performance with lower complexity.

Improved BER Performance of Non-Orthogonal Multiple Access System for Interactive Mobile Users: Maximum Likelihood Detection Perspective

Improved BER Performance of Non-Orthogonal Multiple Access System for Interactive Mobile Users: Maximum Likelihood Detection Perspective

Kernel MSER-DFE Based Post-Distorter for VLC Using Random Fourier Features

Visible light communication (VLC) has emerged as a promising technology that facilitates high speed green communication for the next generation communication systems. However, some of the performance-limiting impairments in VLC include intersymbol interference (ISI), LED's nonlinearity, and multiplicative fading distortion due to user mobility, which present a significant gap between the promised and the achieved throughput of VLC based systems. To mitigate the aforementioned channel impairments, this paper proposes a random Fourier feature (RFF) based kernel minimum symbol error rate (KMSER) decision feedback equalizer (DFE) based post-distorter for VLC, which supports post distortion under finite memory budget. Furthermore, the feedforward, and feedback filter weights are jointly optimized by using a stronger minimum symbol error rate criterion as opposed to the conventional minimum mean square error criterion. Simulations indicate that the proposed RFF-KMSER-DFE based post-distorter exhibits superior BER performance and lower computational complexity over the existing dictionary based post-distorters. Lastly, an analytical bound for BER is derived for the proposed algorithm, and corroborated through simulations.

Comparative Study of Different Antenna Configurations for the MIMOOSTBC Technique Using FEC and the Rayleigh Fading Channel

Background: Multi-Input Multi-Output (MIMO) systems using Orthogonal Space-Time Block Coding (OSTBC) gained extensive popularity in wireless applications owing to the potential of providing improved reliability. Methods: The performance of MIMO - OSTBC systems using error-correcting code (Convolutional, Reed Solomon and Interleaving) schemes used to encode data streams in wireless communications using the Rayleigh channel is reported here. These are subjected to experimentation under modulation schemes such as Quadrature Phase Shift Keying (QPSK). Decoding occurs using the Maximum Likelihood (ML) algorithm, which provides high data rates using spatial domains under the limits of power transmission and limited bandwidths. Results: Different simulations are performed to detect the best BER performance for various antenna configurations and values of antenna configurations with Error Correction so as to use the best outcomes to model the OSTBC. Conclusion: Their effect of improving the overall can be noticed by the advantages of OSTBC with the correcting codes and the maximum number of configurations.

Performance Analysis of Efficient and Low Complexity MIMO-OFDM System Using Modified V-BLAST

Background and Objective: To analyze the performance of MIMO-OFDM system, VBLAST detection suffers from computational complexity as well as high BER. Methods: To improve the BER performance and to reduce the computational complexity of receiver, we propose a modified VBLAST detection in MIMO-OFDM Systems. Results: Simulation using MATLAB shows the improvement in computational complexity and in BER. Conclusion: This modified VBLAST reduces the complexity of MIMO-OFDM System to 44.2% and improvement in BER as compared to conventional VBLAST based MIMO-OFDM System.

NOMA-aided generalized pre-coded quadrature spatial modulation for downlink communication systems

Generalised pre-coding quadrature spatial modulation (GPQSM) is recently proposed to increase the spectral efficiency (SE) of GPSM, which extends the transmitted symbols into in-phase/quadrature domains. In this paper, a novel scheme named non-orthogonal multiple access (NOMA)-aided GPQSM (NOMA-GPQSM), which incorporates the GPQSM scheme into the multi-user communication networks with assist of NOMA, is proposed to further improve the SE and system performance. In NOMA-GPQSM, one base station (BS) is set to serve K users, where user 1 is closest to the BS, and user K is farthest from the BS. In addition, a low-complexity detection method is proposed to reduce the high detection complexity of the maximum-likelihood (ML) detection in successive interference cancellation (SIC) method for all users by NOMA-GPQSM. The theoretical analysis of the BER performance for all users is also derived. Simulation results show that near users achieve relatively good performance, and far users achieve acceptable performance by adjusting power factors for all users in NOMA-GPQSM.

Development of 32-GBaud DP-QPSK free space optical transceiver using homodyne detection and advanced digital signal processing for future optical networks

Free space optical (FSO) communication provides the capacity to deliver high-speed digital data links into the far off and rural factions where topography, set-up cost or groundwork safety pose acute barriers to deployment. The challenges in any FSO system are the transmission impairments and space loss which deteriorate the link performance. This article deals with the design and analysis of a single channel Gray-coded dual polarization-quadrature phase shift keying (DP-QPSK) based FSO communication system with balanced homodyne detection (BHD) and digital signal processing (DSP). We have implemented a series of high-level digital impairment compensation algorithms strategically between the BHD and signal retrieval stages to mitigate the amplitude and phase noise, and compensate for free-space loss. The proposed system exhibits a 3 dB greater receiver sensitivity using optical homodyne detection compared to heterodyne detection. The system performance has been numerically evaluated with regard to bit error rate (BER $$\le 2\times {10}^{-3},$$ i.e. FEC limit), error vector magnitude (EVM), and constellation diagram based on OptiSystem V.16 photonic software. Furthermore, we investigate the joint BER and EVM performance of the proposed system under the influence of launched optical power, laser linewidth, and beam divergence. We obtain the transmission of 32 GBaud DP-QPSK data bearing optical signal up to a link distance of 2.65 km at 128-Gb/s data rate, and an optical signal-to-noise ratio penalty lower than 2.5 dB compared to the back-to-back case. The outcomes of this research demonstrate direct practical relevance and could therefore form the basis for the implementation of next-generation optical wireless networks.

CO-OFDM for bandwidth-reconfigurable optical interconnects using gain-switched comb

We experimentally demonstrate superchannel transmission using CO-OFDM with higher cardinality QAM corresponding to total data rates up to 760 Gbps over 25 km fiber using optical carriers generated from an externally injection locked gain-switched comb source with linewidth ≈19 kHz. Bandwidth re-configurability is demonstrated by operating the comb with different line spacing (20 GHz, 11 GHz) for the choice of (16-/32-/64-) QAM considered and we show the BER performance is within the SD-FEC limit. The system proposed can be used in any short reach application including DCIs and in access networks.

Minimum Error Pursuit Algorithm for Symbol Detection in MBM Massive-MIMO

Media-based modulation (MBM) with massive multiple-input multiple-output (mMIMO) wireless systems is a viable solution to realize the ever-increasing demand for high-speed data and extensive connectivity in beyond 5G and 6G wireless communications. MBM-mMIMO utilizes less transmit power and radio resources measured against mMIMO to yield high spectral efficiency and high data rate. However, symbol detection in the uplink of MBM-mMIMO is challenging due to the sparse nature of the received signal, and the cumulative effect of inter-user interference and noise. In this letter, support recovery error constraint-based low complexity sequential symbol detection technique is proposed for uplink MBM-mMIMO system. The proposed MBM-mMIMO detection technique exploits the upper bound on support recovery error and iteratively minimizes the residual error associated with the estimated transmit vector. A reduced message space is also introduced to further enrich the exploration capability of the proposed technique. Simulation results reveal the viability of proposed techniques over several state-of-the-art MBM-mMIMO detection techniques as BER performance and computational complexity are concerned.

Towards a 20 Gbps multi-user bubble turbulent NOMA UOWC system with green and blue polarization multiplexing.

We experimentally demonstrated a high-speed multi-user green and blue laser diode based underwater optical wireless communication (UOWC) system using non-orthogonal multiple access (NOMA) with polarization multiplexing. The system affords eight users with a record sum rate of 18.75 Gbps over 2-m underwater plus 0.5-m free-space channel. The modulation bandwidths of four detachable optical paths with different wavelengths and polarization states all exceed 1.5 GHz. The results suggest that the flexible balance according to both user fairness and overall throughput/sum rate can be achieved via an appropriate power allocation strategy. The joint optimization of driving current and user assignment ensures the feasibility of providing stable high-speed UOWC for multiple users. With the proposed OFDMA-NOMA scheme, user scale expands by twice while the sum rate for single path reaches 3.2 Gbps. Finally, the BER performances of NOMA modality in turbulent underwater environment with air bubbles of different flow rates are also discussed in detail.

Spatial diversity techniques for non‐line‐of‐sight ultraviolet communication systems over atmospheric turbulence channels

Rich scattering of ultraviolet signals enables the non-line-of-sight outdoor wireless connectivity and eliminates the line-of-sight requirement of free-space optical links. Besides scattering losses, ultraviolet signals also suffer from the atmospheric turbulence-induced fading. One of the strong fading mitigation techniques is the spatial diversity, which has been extensively studied in the context of wireless radio frequency and infrared networks. In this study, spatial diversity techniques for non-line-of-sight ultraviolet communication links are considered. In particular, multiple-input-single-output (MISO), single-input-multiple-output (SIMO), and multiple-input-multiple-output (MIMO) non-line-of-sight ultraviolet communication systems are derived. The BER performance of the single-input-single-output (SISO) link is also derived as a benchmark. The accuracy of the derivations is confirmed through Monte Carlo simulations. The results demonstrate the significant performance improvements in spatial diversity schemes over SISO counterparts. The authors further investigate the effect of spatial correlation on the performance of non-line-of-sight ultraviolet links with spatial diversity. They demonstrate that the spatial correlation degrades the performance significantly, and efficient separation between apertures is crucial to achieve the maximum diversity gain.

Low power sleepy keeper technique based VLSI architecture of Viterbi decoder in WLANs

ABSTRACT .Wireless communication technologies have advanced from cellular networks to satellite systems which create an advancing demand for low power battery operated decoding unit. Widely used error correction technique in the wireless communication systems is the channel coding. In channel coding, convolutional codes are commonly used for the transmission of data over a noisy channel. The methodologies adopted in the proposed design to achieve low power and increase in performance is by designing the architecture of the Viterbi decoder at circuit level design using a sleepy keeper technique, which curtails the leakage power dissipation. The second method is by including the modified register exchange algorithm, which reduces the occurrence of error probability with low power in signal transmission in the wireless domain. Simulation of the design is executed in 45nm TSMC in Tanner-SPICE. Promising results are obtained with reduction in power 31.54% with the CMOS technology for the WLAN frequency of 2.5MHz. BER performance of the design also found to be low in the channel environment.

Secure Data Communication for Wireless Mobile Edge Computing Based on Artificial Noise and Security Code

As increasing threat to wireless mobile edge computing communication and high cost of conventional encryption implement in wireless mobile edge computing environments. The physical layer security has aroused widespread interests to increase the secure transmission and communications of mobile edge computing data communication in wireless networks. This work investigates the mobile edge computing secure communication by MIMO beamforming and artificial noise (AN) system with secure code. From practical consideration, in this work, we consider a coded system and investigate its achievable secrecy rate under the realistic wiretap code with limited code length and modulation. We proposed the mobile edge computing secure transmission scheme which could make almost zero information obtained by the unknown eavesdroppers with keeping certain quality of BER performance for the main channel simultaneously. The simulation results verify this proposed mobile edge computing secure transmission scheme performance. It shows great implement ability.