Low Bit Error Rate Values Research Articles

A 40-Gbps fiber-FSO convergent transmission system employing OFCL-based WDM and external modulation technique

We have proposed and demonstrated a 40Gbps fiber-free space optics (FSO) convergent system based on external modulation and wavelength division multiplexing (WDM) technique. In this experiment, 4010×4 Gbps signal is successfully transmitted employing WDM scheme over 50 km single mode fiber plus 2.5 km FSO distance. Optical frequency comb lines (OFCL) are generated using a continuous wave laser diode, a radio frequency signal generator, a dual drive Mach Zehnder modulator, and an electrical attenuator. OFC lines, having a side mode suppression ratio (SMSR) value of ∼40 dB and flatness of ∼0.4 dB, are employed as broadband laser source in the presented convergent system. The performance of the fiber-FSO system is investigated theoretically for different weather conditions. Very low power penalty with low bit error rate (BER), clear eye diagrams, and standard Q-factor are achieved in the proposed system. The power penalty is restricted within 2.5 dB and 5.8 dB at a BER of 10−9 for 50 km SMF plus 2.5 km FSO distance in clear weather and 50-km SMF plus 0.4-km FSO distance in heavy fog condition respectively. Thus, the proposed WDM-convergent system is efficient enough for high data rate transmission along with low BER value of ∼10−9 and high Q-factor for different environmental scenarios.

A long-reach optically powered multi-band radio-over-fiber network by employing PolM-to-IM converter with enhanced fault-protection ability and less Rayleigh backscattering noise effect

A multi-band radio-over-fiber network is established on polarisation-to-intensity converter with upgraded fault protectivity for transportation of information (10 Gbps/15 GHz, 10 Gbps/60 GHz and 10 Gbps) for end-users over ∼[40 + 30] km single-mode fiber (SMF) link with lessen impairments owing to Rayleigh Backscattering (RB) is proposed and demonstrated. Employment of unalike wavelengths for downstream and upstream results RB minimization. Fault protection capability is uplifted by incorporating the integrated SMF/free-space optics (FSO) link which provides the data continuity condition either through SMF or FSO even when anyone link is in non-workable condition due to damage or environmental limitations. Co-existence of power over fiber (PoF) signal with integrated SMF/FSO scheme was also investigated. Power penalty of 0.74 dB, 0.84 dB, low bit error rate (BER) value (∼10-3for OFDM signal, ∼10-9 for pseudo-random bit sequence (PRBS) signal), <32 dB power budget are achieved by this transmission by employing integrated SMF/FSO scheme and 2.6 dB, 2.1 dB power penalty, 34–35 dB power budget are recorded for transportation of signal in absence of integrated SMF/FSO network. The conjunction of PoF and integrated SMF/FSO scheme enhances the application field areas but causes the transmission distance contraction. Comparatively, lower power penalty than earlier (0.6 dB, 1.7 dB), 29–30 dB power budget, low BER value (∼10-3 for OFDM signal, 10-9 for PRBS signal) are measured for the transmission in presence of integrated SMF/FSO network. Larger power budgets (∼33 dB), ∼2 dB power penalty, expectable BER values are obtained without integrated SMF/FSO network for this transmission.

Design and implementation of DP-DQPSK DWDM transmission system by using direct detection

Designing a system that guarantees both the lower cost implantation, lower complexity on the receiver station side and higher data rate was an essential topic for several researchers recently, in which several methods and approaches were proposed to handle these problems individually and with the best overall outcome. In this work, these problems would be considered by designing and analyzing a novel system based on the combination of Dual Polarization Differential Quadrature Phase Shift Keying (DP-DQPSK) and Dense Wavelength Division Multiplexing (DWDM) technique and by using the Direct Detection (DD) technique. The system was designed with Optisystem software 18 and consist of 64 channels and each channel could transmit 14 Gbps of data rate. The channels 1,6,12,18,24,30,36,42,48,54,60 and 64 were selected as samples among all channels to be investigated and analyzed. Additionally, the proposed system was investigated based on different distances and different parameters of Quality Factor (QF) and Bit Error Rate (BER). The significant contribution of the proposed system is that using the DD would result in a no-required for reference wave and that will result in a less complex system and easier to implement. Results obtained indicate higher quality QF for the sampled channel and lower BER values. For instance, the average QF obtained were in the range of 6.75-8.36 dBm and 6.77-8.35 dBm for data 1 and 2 respectively, which indicates the reliability and efficiency of the proposed system by considering all results obtained from distance variation were above the minimum threshold

Demonstration of 108 Gb/s Duo-Binary PAM-8 Transmission and the Probabilistic Modeling of DB-PAM-M BER

We report 108 Gb/s Duo-Binary PAM-8 (DB-PAM-8) transmission using direct-detection aided by Volterra equalizer. The bit-error-rate (BER) performance of the DB-PAM-8 signal has been evaluated through error counting by varying the bit rate, received optical power, and reach. The experimental results suggest that up to 108, 102, and 84 Gb/s signals can be propagated in back-to-back (B2B), and over 10, and 20 km of standard single-mode fiber (SMF), respectively, below the low-density parity-check forward error correction (LDPC-FEC) threshold. Furthermore, we derive a probabilistic model of the BER for multilevel DB-PAM-M signaling that is verified using our measurements. The model of this important performance metric turned out to be accurate enough, especially at low BER values, where its use is more convenient.

Plasmonic Antenna Embedded Chalcogenide MZI Circuit for Ultra-high Density Up- and Downlink Transmission

A unique device is proposed for ultra-high density up- and downlink transmission. The device comprises of the chalcogenide Mach–Zehnder interferometer (MZI) and panda ring resonator with silver bars at the center microring at the upper and lower parts of the MZI. The device is operative based on the space–time function where the input space (soliton) via the input port multiplexes with time at the add port of the device with a wavelength bandwidth of 1.50–3.50 µm and the frequency bandwidth of 85–250 THz. The WGM is observed at the upper (uplink) and lower (downlink) center microring with suitable parameters. The silver bars at the center microring form the dipole oscillation, where the uplink and downlink plasmonic antennas have the directivity 18.68 and 13.27, and gain is 9.34 and 6.64, respectively. The light fidelity (LiFi uplink and downlink) employs the wavelength spectrum while the wireless fidelity (WiFi uplink and downlink) employs the frequency spectrum. The LiFi uplink and downlink have an optimum wavelength of 2.30 µm and 2.27 µm, respectively, while the WiFi uplink and downlink have an optimum frequency of 130 THz and 132 THz. For the transmission signal, the bit rate of 28 Pbits−1 is achieved. The bit error rate (BER) value of 0.36 is obtained which indicates the system performance. Low BER value indicates high system performance. The device can be employed for the coverage of the light-wave and microwave wavelength link for 6G communication, where AI (artificial intelligence), 3D communication, code encryption, and secured transmission can be applied.

TRAFFIC MODELING IN UAV/RPAS COMMUNICATION CHANNEL

This study is devoted to obtaining the traffic characteristics of communication channel between the Remotely Piloted Air System (RPAS) and the Base Station, the model of which was created in professional software NetCracker. The dependencies of dropped packets, message Travel Time (TT) and HUB Average Utilization on the Transaction Size (TS), the link bandwidth and the Bit Error Rate (BER) for different distribution laws of Time Between Transactions (TBT) were analyzed. It was observed that for smaller TBT the lower transaction size can be transmitted, which is true for all distributions. But the lowest percentage of packet loss is observed for the LogNormal distribution. Additionally, it was observed that the TT does not depend on the value of the TBT parameter with the Exponential or LogNormal distribution laws, which is not true for the Const law. Hub utilization does not exceed ≈ 20% for all distributions with 1 s TBT. Nevertheless, the maximal TS for LogNormal law is ten times bigger than for other laws. The transaction TT decreases with the transmission rate increase, and for T3 bandwidth it equals to 0.5 s approximately for all considered distributions. However, the smallest percentage of packet loss and HUB utilization is observed for the LogNormal law. The TT does not exceed 1 s for low BER values for all TBT distributions. Such numerical analysis allows us set up and change traffic parameters while observing the results under specified transmission modes.

Compressed sensing Kalman filter estimation scheme for MIMO system under phase noise problem

Phase noise problem in oscillators can degrade the performance of high-speed communication systems. The author analysed the impact of phase noise problem on multi-input–multi-output (MIMO) systems under common and independent oscillators. The estimation of system parameters (i.e. phase noise and channel gains) is a challenging task. In this study, a data-aided least square estimator based compressed sensing Kalman filter (KF)-based compressed sensing (CS) scheme is proposed for tracking phase parameters. The signal model and estimation problem for the system are mathematically derived. Also, Bayesian Cramér–Rao lower bound (BCRLB) scheme is also derived. For joint estimation, the mean square error (MSE) and bit error rate (BER) performances of the BCRLBs and proposed scheme are compared. Results demonstrate that the proposed KF-based CS scheme gives low BER values and better performance compared to other estimation schemes. The utilisation of the proposed scheme helps in reducing the MSE of the MIMO system. Finally, the proposed scheme enhances the estimation of phase noise parameters for the MIMO system.

Adaptive Selection Combiner over Log-normal Fading Channel in Wireless Communication System

Wireless communication system has found worldwide acceptability in providing acceptable services due to its portability, flexibility and ease of usage. However, the system is characterized by severe multipath propagation effects that degrade its performance. Selection Combiner (SC) as one of the techniques being used to address this problem is associated with poor performance due to fixed constellation of the modulation scheme. Hence, in this paper, an Adaptive Selection Combiner (ASC) using Constellation Adaptation Algorithm (CAA) with an expression over Log-normal fading channel is proposed. ASC is developed using conventional SC (CSC) and CAA. Ten thousand randomly generated bits are modulated using each of Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM) schemes. The modulated signals at varying paths are scanned by CSC to choose a path with the highest Signal to Noise Ratio (SNR). The output of SC which is a function of Channel State Information (CSI) acquired is used to determine the channel gain. The constellation size is then adjusted based on the value of channel gain through CAA. The proposed adaptive technique is simulated using MATLAB software and evaluated using Bit Error Rate (BER) to determine its performance. The results obtained show that ASC gives lower BER values than CSC due to the self-adjustment of the constellation size. Therefore, the proposed ASC can be deployed to improve the performance of wireless communication systems.

Practical BER-Based Estimation of Residual OFDM CFO by Reducing Noise Margin

The main OFDM drawbacks are Carrier Frequency Offset (CFO) and large Peak-to-Average Power Ratio (PAPR), which both degrade the Bit Error Rate (BER). Specifically, we consider here clipping or any other PAPR reduction method sufficient to prevent the nonlinear high-power amplifier from generating errors. Moreover, in small cells, the signal-to-noise ratio is large, while the small time dispersion allows the OFDM symbol cyclic prefix to prevent intersymbol interference. This retains the CFO to solely determine the BER and vice versa, enabling indirect estimation of CFO-induced phase distortion by simple BER testing. However, a particular problem is measuring very low BER values (generated by alike residual CFO), which could last a long time in order to acquire statistically enough errors. The test time can be drastically reduced if the noise margin is reduced in a controllable way, by adding the interfering signal to each subcarrier at the receiver. This approach is shown to enable efficient and accurate short-term BER (and so CFO phase error) testing.

Suitable Spreading Sequences for Asynchronous MC-CDMA Systems

In order to meet the demand of high data rate transmission with good quality maintained, the multi-carrier code division multiple access (MC-CDMA) technology is considered for the next generation wireless communication systems. However, their high crest factor (CF) is one of the major drawbacks of multi-carrier transmission systems. Thus, CF reduction is one of the most important research areas in MC-CDMA systems. In addition, asynchronous MC-CDMA suffers from the effect of multiple access interference (MAI), caused by all users active in the system. Degradation of the system’s bit error rate (BER) caused by MAI must be taken into consideration as well. The aim of this paper is to provide a comparative study on the enhancement of performance of an MC-CDMA system. The spreading sequences used in CDMA play an important role in CF and interference reduction. Hence, spreading sequences should be selected to simultaneously ensure low CF and low BER values. Therefore, the effect that correlation properties of sequences exert on CF values is investigated in this study. Furthermore, a numerical BER evaluation, as a function of the signal-to-noise ratio (SNR) and the number of users, is provided. The results obtained indicate that a trade-off between the two criteria is necessary to ensure good performance. It was concluded that zero correlation zone (ZCZ) sequences are the most suitable spreading sequences as far as the satisfaction of the above criteria is concerned.

Enhancement of Maximal Ratio Combiner over Log-Normal Fading Channel using Firefly Algorithm

Wireless communication system has a great impact in the world of telecommunication and is expected to be a leading role in the developing a nation. However, the system is characterized by multipath propagation effects that lead to signal fluctuation at the receiver, thereby degrading the performance of the system. Maximal Ratio Combiner (MRC) being used to address this problem is characterized with hardware complexity that results in long processing time. Therefore, in this paper enhancement of MRC with closed form expression over Log-Normal fading channel is carried out using Firefly Algorithm (FA) at the receiver. FA create a flashing light in associated with Signal to Noise Ratio (SNR) of the received signal and output the signal with highest SNR. Randomly generated bits used as source data are modulated using M-ary Quadrature Amplitude Modulation (M-QAM) and transmitted over Log-Normal fading channel to generate resultant signals. The resultant signals at varying paths ‘L’ (2, 3, 4) are optimized by FA. The outputs of the FA are combined by MRC to obtain the received signal and converted to baseband through demodulation. A mathematical expression using the Probability Density Function (PDF) of Log-Normal fading channel at varying paths ’L’ for Bit Error Rate (BER) is also derived. The technique is simulated using MATLAB 7.4. The performance is evaluated using Signal-to-Noise Ratio (SNR), Bit Error Rate (BER) and Processing Time (PT). The result shows that, the enhanced MRC (eMRC) gave lower BER values when compared with conventional MRC with reduction in hardware complexity. The eMRC carried out can be used to enhance the performance of wireless communication system.

Pengiriman Citra pada Komunikasi Cahaya Tampak IEEE 802.15.7 Lapisan Fisik II.f-n

Visible light communication (VLC) is a communication technology using visible light as a transmission medium that can have larger bandwidth than other wireless communications. VLC has a standard of IEEE 802.15.7 which has two layers. One of the layers is Physical Layer (PHY) II which has characterictic for indoor and line of sight communication. In this layer, the standard for data rate and optical clock rate is higher than the other types of layers using on off keying (OOK) modulation. This research investigated variation effect of clock rate, data rate, and Reed Solomon (RS) coding to bit error rate (BER) of the received signal. Nowadays, mostly data are pictures and videos. So, this research also test the VLC PHY II to transmit a picture under the varied conditions using peak signal to noise ratio (PSNR). All investigations are built in simulation. The results show that the lower RS coding rates, the lower BER values, and the higher optical clock rate, the higher data rate obtained. Good quality of picture is obtained with BER 10-4 and PSNR 39 dB.

Fourier Rotman Lens Enabled Directional Modulation Transmitter

A 10 GHz Fourier Rotman lens enabled dynamic directional modulation (DM) transmitter is experimentally evaluated. Bit error rate (BER) performance is obtained via real-time data transmission. It is shown that Fourier Rotman DM functionality enhances system security performance in terms of narrower decodable low BER region and higher BER values associated with BER sidelobes especially under high signal to noise ratio (SNR) scenarios. This enhancement is achieved by controlled corruption of constellation diagrams in IQ space by orthogonal injection of interference. Furthermore, the paper gives the first report of a functional dual-beam DM transmitter, which has the capability of simultaneously projecting two independent data streams into two different spatial directions while simultaneously scrambling the information signals along all other directions.

A New Parallel Concatenated Coding Transceiver System Using Three Convolutional-Interleaver Sections

Channel coding is an important stage in any communication system and is used for improving the Bit Error Rate (BER) performance in wireless digital communication systems in various communication channels such as the Additive White Gaussian Noise (AWGN), Rayleight, Ricean channels, and so on. One of the important types of channel coding is the Concatenated coding. This type of coding achieves low BER with large gain especially in the AWGN channel. In the presented paper, a new coding system is proposed and simulated based on parallel concatenated coding. Three convolutional encoders are used with various interleaver block length. The proposed coding system is simulated using Matlab package ver. R2007a. Low BER values are achieved with convolutional rate of 1/4 with interleaver length N = 4000 bit as compared with other interleaver length and convolutional rates.

Near-Capacity Three-Stage Turbo Detection of Irregular Convolutional Coded Joint Sphere-Packing Modulation and Space-Time Coding

Conventional two-stage turbo-detected schemes typically suffer from a Bit Error Rate (BER) floor, preventing them from achieving infinitesimally low BER values, especially, when the inner coding stage is of non-recursive nature. We circumvent this deficiency by proposing a three-stage turbo-detected Sphere Packing (SP) aided Space-Time Block Coding (STBC) STBC-SP scheme, where a rate-1 recursive inner precoder is employed to avoid having a BER floor. The convergence behaviour of this serially concatenated scheme is investigated with the aid of 3D Extrinsic Information Transfer (EXIT) Charts. Furthermore, the capacity of the STBC-SP scheme is determined and an algorithm is proposed for calculating a tighter upper bound on the maximum achievable bandwidth efficiency, based on the EXIT charts of the STBC-SP demapper. The proposed three-stage turbo-detected scheme operates within about 1.0 dB of the capacity and within 0.5 dB of the maximum achievable bandwidth efficiency limit.

DOWN-LINK CATV/FTTH AND UP-LINK FTTH TRANSPORT SYSTEMS BASED ON REFLECTIVE SEMICONDUCTOR OPTICAL AMPLIFIER

A down-link CATV/fiber-to-the-home (FTTH) and uplink FTTH transport system employing a reflective semiconductor optical amplifier (RSOA) as wavelength reuse and remodulation schemes is proposed and experimentally demonstrated. By using −1 side mode injection-locked/optoelectronic feedback techniques, brilliant performances of carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple beat (CTB), and bit error rate (BER) were obtained for downlink transmission; low BER value was also achieved for up-link transmission over a 50-km single-mode fiber (SMF) transmission. Such a CATV/FTTH transport system is suitable for broadband access fiber networks.

Bit Error Rates for Focused General-type Beams

Using the scintillation index of general beam formulation, bit error rate (BER) is investigated for focused Gaussian, cos-Gaussian, cosh-Gaussian and annular beams in weak atmospheric turbulence. We have employed our previously derived formulation of the scintil- lation index of these beams by Rytov method. Rytov method scintillation theory is known to yield accurate results for focused beams on horizontal paths under certain regions. Therefore we flnd the scintillation indices of the mentioned beams for the valid region. Using the log-normal distributed intensity, BER values versus signal-to-noise ratio (SNR) are calculated for Gaus- sian, cos-Gaussian, cosh-Gaussian and annular beams. In our study, the focal lengths (radius of curvature) of all the mentioned focused beams are equal to the propagation distance. The improvement of BER is observed for variations of propagation length, source size and wavelength of operation. Based on these parameters, BER values of Gaussian, cos-Gaussian, cosh-Gaussian and annular beams are compared. BER values we found for the focused Gaussian, cos-Gaussian, cosh-Gaussian and annular beams decrease with increasing source sizes. Likewise, BER values of focused Gaussian, cos-Gaussian, cosh-Gaussian and annular beams decrease with increasing wavelength. The focused annular beam attains the lowest BER value for small source sizes and long propagation distances. Moreover, BER for focused beams is compared with their collimated counterparts. We observe that focused beams have lower BER values than the collimated beams on horizontal paths. Our formulation can easily be extended to cover corresponding higher order beams, however in this paper we concentrate mainly on the zero order beams.

Bit error rates for general beams

In order to analyze the effect of beam type on free space optical communication systems, bit error rate (BER) values versus signal-to-noise ratio (SNR) are calculated for zero order and higher order general beam types, namely for Gaussian, cos-Gaussian, cosh-Gaussian, and annular beams. BER analysis is based on optical scintillation using log-normal distribution for the intensity, which is valid in weak atmospheric turbulence. BERs for these beams are plotted under variations of propagation length, source size, wavelength of operation, and order of the beam. According to our graphical outputs, at small source sizes and long propagation distances, the smallest BER value is obtained for the annular beam. On the other hand, at large source size and small propagation distance, the smallest BER value is obtained for the cos-Gaussian beam. Moreover, our study of the order of the beam shows that higher order beams have lower BER values than the zero order beams at longer propagation distances. But this drop compared with the order seems to be incremental.

A hybrid analytical-simulation procedure for performance evaluation in M-QAM-OFDM schemes in presence of nonlinear distortions

Presents a hybrid analytical-simulation procedure for performance evaluation in M-ary quadrature amplitude modulation (M-QAM) orthogonal frequency-division multiplexing (OFDM) digital radio systems in the presence of distortions caused by high-power amplifiers (HPAs). The present analysis is carried out considering an additive white (AWGN) transmission channel. It is shown that, in the case of an OFDM system with a large number of subcarriers, the distortion on the received symbol caused by the amplifier can be modeled, with good approximation, as a Gaussian noise added to the received symbol. This important result allows a hybrid analytical-simulation approach to solve the problem of performance evaluation. In practice, the simulation aspect is only used to estimate means and variances of the nonlinear noise. Such estimated parameters are subsequently used to evaluate analytically the system bit-error rate (BER) using an expression, which takes into account both AWGN and nonlinear noise effects. The advantage of the proposed method lies in the strongly reduced computational time. In fact, an accurate estimate of the nonlinear noise parameters requires only few iterations when compared with a classical semianalytical approach. This is especially true when low BER values (<10/sup -4/) have to be estimated. The proposed procedure is applied to evaluate M-QAM-OFDM performance in the presence of distortions caused by traveling-wave tube (TWT) and solid-state-power (SSP) amplifiers.

Comparison of diversity combining techniques for Rayleigh-fading channels

Several methods of diversity combining for a Rayleigh-faded channel are evaluated and compared. The methods considered are, for coherent reception, maximal ratio combining (MRC), selection combining (SC), and a generalization of SC, whereby the two (three) signals with the two (three) largest amplitudes are coherently combined. We will call this method second (third) order SC, and denote it SC2 (SC3). Similar techniques are also investigated for noncoherent reception, with equal gain combining (EGC) replacing MRC, and noncoherent versions of SC2 and SC3. Numerical results indicate that SC2 and SC3 significantly enhances the bit-error rate (BER) performance relative to that achievable with SC, and under certain conditions approaches the performance achieved by MRC or EGG. The performance enhancement of SC2 and SC3 is especially noticable for noncoherent reception, where EGC is seen to provide the best performance only for low BER values. In fact, when the BER is 10/sup -3/ or greater, SC2 and SC3 performed comparably to EGG, and in some cases performed better than EGC.