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Spectrally efficient 16 quadrature amplitude modulation‐orthogonal frequency division multiplexing (QAM‐OFDM) system using specifications of commercially available high‐power phosphorous coated LED (PLED) is proposed in this study. To address the challenges of signal attenuation and limited bandwidth, systems integrated with a band pass filter (BPF) after the photodetector and optical preamplifier. The effect of BPF bandwidth and preamplifier gain on the performance of 16 QAM‐OFDM system have been investigated. Results demonstrated that 375 MHz bandwidth evaluated from 1.5 × symbol rate, offered an optimum performance achieving minimum bit‐error‐rate of 3.05 × 10−4. For preamplifier gain of 20 dB, we achieved a maximum distance of 3 m which is limited to 1.5 m for lower gain values. With BPF‐optimized bandwidth and a preamplifier gain of 20 dB, we have achieved a data rate of 5 Gbps for maximum distance up to 2 m while considering the super‐forward‐error‐correction limit of 1.863 × 10−2. With data rate of 6 and 7 Gbps, the distance lower down to 1.8 and 1.5 m, respectively. [ABSTRACT FROM AUTHOR]

5G has been essentially a buzzword for several years, but according to the experts, from 2022 onward, there will be an inflection point between network maturity and the availability of 5G. To make 5G a reality, we must minimize all propagation losses. One of the possible factors that reduces the performance of 5G transmission is the multipath effect. In this paper, we investigate the severity of the multipath effect in the 5G millimeter-wave (mmWave) channel and mitigate the multipath effect using adaptive equalization based on the least mean square (LMS) algorithm to improve the performance of 5G wireless signal transmission. A mmWave channel simulator, NYUSIM, provides complete data for all resolvable multipaths in a specific channel configuration. An analysis of bit-error-rate (BER) based on the minimum BER (MBER) and minimum mean square error (MMSE) optimization criterion is performed to measure the improved performance of a 5G data channel simulated under line-of-sight (LOS) and non-LOS (NLOS) paths. A good overall performance of BER based on the MBER and MMSE criteria is attained using the LMS equalization method in a micro-urban area at a maximum data rate of 50 Mbps. For both LOS and NLOS conditions, the increase in data rate to 55.56 Mbps and 62.5 Mbps causes a significant decrease in BER performance. In conclusion, the primary factor affecting the BER performance is the data rate, not the frequency or transmitter-to-receiver distance. [ABSTRACT FROM AUTHOR]

Improvement in the performance of uplink and downlink optical communication systems by means of receive diversity and adaptive optics correction is investigated. We develop a communication system model using adaptive optics correction in the transmitter and maximum ratio combining diversity technique in the receiver. The effect of adaptive optics correction modes, receive diversity, zenith angle, link length, wind speed and the height of transmitter/receiver on the ground are evaluated. Performance improvement is observed with both adaptive optics correction and the receive diversity. It is aimed to provide researchers an option to determine the method they will use to reduce the effect of turbulence. As the numerical values of the main results, we report that adaptive optics correction with 5 mode Zernike removal reduces BER from 1 0 - 8 to 1 0 - 10 for one receiver. When the number of receivers is 6, BER is found to reduce from 1 0 - 6 to 1 0 - 12 . The results obtained in this study can be beneficial to optimize the design of the slant path uplink and downlink optical communication links between the ground and low-orbit satellites that are exposed to atmospheric turbulence. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation (MCM) technique that divides the wide bandwidth into parallel narrow bands, each of which is modulated by orthogonal subcarriers. Currently, OFDM is a high-spectral efficiency modulation technique that is used in a variety of wired and wireless applications. The transmitted signal in a wireless communication channel spreads from transmitter to receiver through multiple reflective paths. This triggers multipath fading, which causes variations in the received signal's amplitude and phase. Slow/fast and frequency-selective/frequency-nonselective are the main types of multipath fading channels. Therefore, in this paper, we proposed new models for modeling multipath fading channels, such as the exponential fading channel and the Gamma fading channel. In addition, new bit-error-rate (BER) derivations have been derived. The performance of the OFDM system over proposed channel models has been evaluated using Monte-Carlo simulation and compared to the Rayleigh fading channel model. The obtained results via simulations show that the exponential fading channel at a rate parameter (λ=0.5) outperforms the Rayleigh fading channel by 6 dB for all values of Eb/No, while the Gamma fading channel at (α=2) outperforms the Rayleigh fading channel by 3 dB for all values of Eb/No. [ABSTRACT FROM AUTHOR]

Silicon photonics is a promising technology for high-performance inter/intra-chip networks. Although chiplet technologies help to integrate photonic network with processors and memories, thermal reliability remains a major challenge for photonic networks. Thermal variations are common in chiplet-based systems. Due to thermo-optic effects, photonic switches, such as microresonators (MRs), suffer from temperature-dependent wavelength shifts. To improve the thermal reliability of photonic chiplets, we propose an effective bridging and tuning method, called BAT. Our method enhances the temperature channel transition among MRs and minimize bit errors during temperature changes. BAT is integrated with thermal tuning, electrical tuning, laser tuning, and receiver tuning. We optimize MR design, control logic, tuning circuit, thermal floorplan, and network protection mechanism for BAT. Compared to state-of-the-art methods, BAT achieves a 1 0 − 12 bit-error-rate for photonic chiplets, saves up to 70.0% of the thermal tuning power, and improves up to a 1.17X system energy efficiency. • A joint tuning method BAT is proposed to achieve thermal reliable photonic chiplets. • A new optical bridging method is presented to avoid the data transmission errors. • Cross-layer design of BAT involves control logic, thermal placement and network agent. • BAT has better performance regarding control stability, BER, and system performance. [ABSTRACT FROM AUTHOR]

The impact of Electromigration (EM) on the Bit-Error-Rate (BER) of signal interconnect paths was experimentally examined. An array-based test-vehicle for tracking Bit-Error-Rate (BER) degradation of signal interconnects subject to Direct-Current (DC) EM stress was implemented in a 16nm FinFET process. A unit interconnect path comprises five identical interconnect stages where each wire is driven by inverter based buffers. Accelerated EM stress testing is achieved entirely on-chip using metal heaters located directly above the devices-under-test (DUTs) and separate stress circuits driving both ends of the wire. The proposed test structure features a ring-based Voltage-Controlled-Oscillator (VCO), a bit-pattern generator and local BER sampling monitors which enable bitwise tracking of ‘0’ and ‘1’ errors separately, further simplifying the overall test-setup and allowing for high precision characterization of EM induced resistance shifts using only digital circuits. Measurement data collected from the 16nm prototype reveals unique insights into EM induced signal path degradation that was not available prior to this work. Our experimental studies suggest that monitoring the BER of an interconnect path could be used as a new metric for capturing EM induced resistance shifts in a real system, in lieu of the conventional approach which focuses on monitoring standalone wire resistances. Supplemental simulations showcasing the projected degradation in the interconnect path operating frequency as a function of stress time constructed from resistance traces sampled from identical wires implemented in the same process reaffirm the measurement trends. [ABSTRACT FROM AUTHOR]

Recent research investigates the decode-and-forward (DF) relaying for mixed radio frequency (RF) and terahertz (THz) wireless links with zero-boresight pointing errors. We analyze the performance of a fixed-gain amplify-and-forward (AF) relaying for the RF-THz link to interface the access network on the RF technology with wireless THz transmissions. We develop probability density function (PDF) and cumulative distribution function (CDF) of the end-to-end SNR for the relay-assisted system in terms of bivariate Fox’s H function considering $\alpha $ - $\mu $ fading for the THz system with non-zero boresight pointing errors and $\alpha $ - $\kappa $ - $\mu $ shadowed ($\alpha $ -KMS) fading model for the RF link. Using the derived PDF and CDF, we present exact analytical expressions of the outage probability, average bit-error-rate (BER), and ergodic capacity of the considered system. We also analyze the outage probability and average BER asymptotically for a better insight into the system behavior at high SNR. We use simulations to compare the performance of the AF relaying having a semi-blind gain factor with the recently proposed DF relaying for THz-RF transmissions. [ABSTRACT FROM AUTHOR]

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Power domain non-orthogonal multiple access (PD-NOMA) has been widely recognized a spectrum-efficient multi-user transmission method when the channel gains across different users vary obviously. Due to the long travel distance between the space and the Earth in satellite communication scenarios, the advantages from PD-NOMA will disappear since the signals experience almost the same path loss. However, in hybrid satellite networks, terrestrial users equipped with different size antennas may lead to various receiving gains, which are equivalent to diverse channel gains. In this paper, by deeply exploiting such a characteristic, we propose a power domain multiplexing based co-carrier transmission method in a hybrid satellite network. Superposing a weak signal on a strong one, two signals are enabled to be transmitted on the same carrier with the bandwidth of the strong signal. To guarantee the signals are decodable at both sides, a user pairing strategy is investigated in detail, and the performance gain of the new method is further analyzed. Simulation results show that a carrier resource can be saved in the proposed method with the sacrifice of a marginal bit-error-rate performance.

Massive multiple-input multiple-output (massive-MIMO) is a promising technology for next generation wireless communications systems due to its capability to increase the data rate and meet the enormous ongoing data traffic explosion. However, in non-reciprocal channels, such as those encountered in frequency division duplex (FDD) systems, channel state information (CSI) estimation using downlink (DL) training sequence is to date very challenging issue, especially when the channel exhibits a shorter coherence time. In particular, the availability of sufficiently accurate CSI at the base transceiver station (BTS) allows an efficient precoding design in the DL transmission to be achieved, and thus, reliable communication systems can be obtained. In order to achieve the aforementioned objectives, this paper presents a feasible DL training sequence design based on a partial CSI estimation approach for an FDD massive-MIMO system with a shorter coherence time. To this end, a threshold-based approach is proposed for a suitable DL pilot selection by exploring the statistical information of the channel covariance matrix. The mean square error of the proposed design is derived, and the achievable sum rate and bit-error-rate for maximum ratio transmitter and regularized zero forcing precoding is investigated over different BTS topologies with uniform linear array and uniform rectangular array. The results show that a feasible performance in the DL FDD massive-MIMO systems can be achieved even when a large number of antenna elements are deployed by the BTS and a shorter coherence time is considered. [ABSTRACT FROM AUTHOR]

Silicon photonics is the leading candidate technology for high-speed and low-energy-consumption networks. Thermal and process variations are the two main challenges of achieving high-reliability photonic networks. Thermal variation is due to the heat issues created by application, floorplan, and environment, while process variation is caused by fabrication variability in the deposition, masking, exposition, etching, and doping. Tuning techniques are then required to overcome the impact of the variations and efficiently stabilize the performance of silicon photonic networks. We extend our previous optical switch integration model, BOSIM, to support the variation and thermal analyses. Based on device properties, we propose indirect feedback tuning (IFT) to simultaneously alleviate thermal and process variations. IFT can improve the BER of silicon photonic networks to 10−9 under different variation situations. Compared to state-of-the-art techniques, IFT can achieve an up to 1.52 × 108 times bit-error-rate improvement and 4.11X better heater energy efficiency. Indirect feedback does not require high-speed optical signal detection, and thus, the circuit design of IFT saves up to 61.4% of the power and 51.2% of the area compared to state-of-the-art designs. [ABSTRACT FROM AUTHOR]

Imperceptible, robust, and embedding capacity are three main requirements for the steganography of digital audio signal. To enhance them, this study presents a novel steganography for digital audio signal in the wavelet domain. Since the performance of imperceptible and robust are usually in term of signal-to-noise ratio (SNR) and bit-error-rate (BER), we propose a quantization-based optimization model to maximize SNR and reduce BER in embedding secret message. In the proposed model, quantization technique with unknow coefficients of discrete wavelet transform (DWT) is rewritten as the first constraint. The adjustment of scaling DWT coefficients is considered as the second constraint. At the same time, signal-to-noise ratio (SNR) is converted into a performance index. In solving this model, we use matrix operations and Lagrange multiplier to obtain optimal DWT coefficients and scaling factors. Moreover, the invariant feature of the scaling factors against amplitude scaling attack is proved. In extraction, secret message can be detected without original audio signal. Experimental results show that the proposed steganography has high SNR and strong robustness against many malicious attacks when comparing to some exiting methods. [ABSTRACT FROM AUTHOR]

In recent times, many MAC protocols were implemented for boosting and improving energy efficiency (EE) in WSNs. Moreover, the cooperative MIMO method is found to be much capable of enhancing the EE of WSNs if configured properly. This paper intends to propose cross-layer design for multihop virtual MIMO system to enhance the end-to-end (ETE) reliability, EE, and QoS of the adopted WSN. The protocol is set here to focus on the energy utilization for transmission of data packets by optimal selection of transmission constraints for each node of the network. Moreover, the protocol's ETE latency and throughput are also modeled as the dependent variables of BER performance of every link. To discover the improved BER criteria of each link that meets the ETE QoS requirement in reduced energy utilization, this paper employs a new hybrid optimization algorithm named Lion Mutated Dragonfly Algorithm (LM–DA) that is a hybrid variant of both Lion Algorithm (LA) and Dragonfly Algorithm (DA). Finally, the performance of the adopted scheme is validated over other state-of-the-art models. The results state that the energy consumed by the adopted LM–DA approach is about 2.65%, 1.77%, and 1.77% reduced over LA, PSO, and DA schemes, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we consider the fundamental and most studied non-coherent differential chaotic shift keying system under a pulse jamming environment. We devote our effort to propose a novel correlation receiver with nonlinearity blanking for the considered system to improve its anti-jamming performance. In addition and importantly, we also propose a mathematical framework to derive an optimal blanking threshold for the proposed receiver. The proposed nonlinearity blanking mechanism basically blocks the received signals with a larger amplitude than the blanking threshold, while the signals with a smaller amplitude are not affected at all. We then show that the proposed receiver with optimal blanking threshold significantly outperforms the conventional correlation counterpart.

Evolution and accessibility of smart‐phones have led to a huge demand in network bandwidth. The ubiquitous use of smart‐phones in high‐speed trains poses a unique challenge in delivering high‐speed internet service on board. This challenge can be overcome by employing free‐space optics, an alternative to radio‐frequency technology. Previous coverage models for ground–train communications employed single laser systems with a larger divergence angle to cover a larger distance. Larger divergence angles lead to larger geometric losses, which may result in a non‐reliable communication link. This study proposes a sectorised multi‐beam coverage model with a smaller divergence angle to reduce the impact of geometric losses in the system. This study also proposes two receiver (Rx) architectures for Rxs deployed on the train. Along with geometric losses, the atmospheric attenuation is taken into consideration for the FSO link. The performance of the ground–train communications system in terms of bit‐error‐rate is evaluated under weak turbulence conditions via numerical simulation. [ABSTRACT FROM AUTHOR]

Busbar distribution system is used as a modular infrastructure to carry electrical energy in low voltage grid. Due to the widespread usage in industrial areas, the power line communication possibilities should be investigated in terms of smart grid concept. This paper addresses modeling of the busbar distribution system as a transmission line and gives some suggestions on the link performance for narrowband power line communication for the first time in literature. Firstly, S-parameters of different current level busbars were measured up to 500 kHz for all possible two-port signal paths. The utilization of the frequency-dependent model was proposed to extract transmission line characteristics to eliminate the unwanted measurement effects. Particle swarm algorithm was used to optimize the model parameters with a good agreement between measured and simulated S-parameters. Additionally, link performance of busbar distribution system as a power line communication channel at 3 kHz-148.5 kHz band was examined for frequency shift keying and phase shift keying modulations under different network configurations such as varying busbar type, the line length between transmitter and receiver, branch number, and terminating load impedance. Obtained results were presented as bit-error-rate vs. signal to noise ratio graphs.

Sequences are used for achieving non-linearity in a cryptosystem, and they are important in Code Division Multiple Access (CDMA) to ensure a proper communication. In this study, we show a method for obtaining cryptographic functions from p-ary sequences with s consecutive zero-symbols of type (γ1, γ2). In fact, most of the cases we obtain functions with the highest non-linearity, i.e. generalized bent functions. In CDMA, instead of distributing time and frequency sources to users, each user is given a unique sequence to transmit data at the same frequency and time. In this study, we examined the bit-error-rate (BER) performance of p-ary sequences with s consecutive zero-symbols of type (γ1, γ2) on CDMA. [ABSTRACT FROM AUTHOR]

In this brief, we consider an advanced noise reduction differential chaotic shift keying system in which a single antenna source communicates with a single antenna destination under the attack of a single antenna jammer. We design an anti-jamming receiver for the considered system. Particularly, we propose a variational mode decomposition—independent component analysis—wavelet packet decomposition (VMD-ICA-WPD) structure, in which VMD method is first exploited to generate multiple signals from the single received one. Second, ICA method is applied to coarsely separate chaotic and jamming signals. After that, WPD method is used to finely estimate and mitigate jamming signals that exist on all outputs of ICA method. Finally, an inverse ICA procedure is carried out, followed by a summation, and the outcome is passed through the conventional correlation receiver for recovering the transmitted information. Simulation results show that the proposed receiver provides significant system performance enhancement compared to that given by the conventional counterparts. [ABSTRACT FROM AUTHOR]

The Inter-Carrier-Interference (ICI) is considered a bottleneck in the utilization of Multiple-Input-Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems, due to the sensitivity of the OFDM towards frequency offsets which lead to loss of orthogonality, interference and performance degradation. In this paper Residue Numbers as a coding scheme is impeded in MIMO-OFDM systems, where the ICI levels is measured and evaluated with respect to conventional ICI mitigation techniques implemented in MIMO-OFDM. The Carrier-to-Interference Ratio (CIR), the system Bit-Error-Rate (BER) and the Complementary Cumulative Distribution Function (CCDF) for MIMO-OFDM system with Residue Number System (RNS) coding are analyzed and evaluated. The results had demonstrated a performance of transmission model with and without RNS. [ABSTRACT FROM AUTHOR]

Abstract The analytical expression of the spherical wave Rytov variance β 0 2 in oceanic turbulence is derived by using the Elamassie's power spectrum model (EPSM), and its correction is confirmed. The performance indicators of underwater laser radar systems, including the double-pass scintillation index σ I 2 , the aperture averaging factor A , the mean signal-to-noise ratio SNR and the mean bit-error-rate BER of monostatic system (MS) and bistatic system (BS) in oceanic turbulence are investigated. On the other hand, the difference of β 0 2 , σ I 2 and SNR between EPSM and Nikishov's power spectrum model (NPSM) is also studied. It is found that, in weak and moderate turbulence, σ I 2 is underestimated by NPSM when oceanic turbulence is dominated by the temperature fluctuations, while σ I 2 is overestimated by NPSM when oceanic turbulence is dominated by the salinity fluctuations. However, it is inverse situation in strong turbulence. Furthermore, the behavior of SNR between EPSM and NPSM is different from that of σ I 2. The relative difference of σ I 2 and SNR between EPSM and NPSM is larger for MS than that for BS. The relative difference of σ I 2 and SNR between EPSM and NPSM is larger in weak and moderate turbulence than that in strong turbulence. [ABSTRACT FROM AUTHOR]

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

Abstract With the advancement of Internet Technology, a lot of multimedia content is shared over the Internet resulting in several concerns over multimedia content like copyright protection, content authentication, and ownership. In this paper, we have developed a novel watermarking scheme for Advanced Video Coding (MPEG-4 AVC) videos using Bi-directional Extreme Learning Machine (B-ELM). Relevant frames to be watermarked are identified by implementing a newly developed fuzzy algorithm based on threshold operation. A binary watermark, encrypted by transposition cipher, is used to ensure enhanced security. The proposed watermarking scheme has been tested on five benchmark videos (Akiyo, Hall_Monitor, Mother_Daughter, Pamphlet, and Silent). High average Peak Signal to Noise Ratio (PSNR) values of the signed video sequences indicate good visual quality post-embedding. Common video interferences such as scaling, noising, cropping, filtering, frame dropping, frame averaging, and frame swapping are used to evaluate the robustness of the watermark embedding scheme. The high values of Normalized Correlation (N C (W , W ′)) and Bit-Error-Rate (B E R (W , W ′)) between the original watermark (W) and the recovered watermark (W ′) establish the good robustness of the proposed scheme. While the established algorithms such as Fuzzy Inference System (FIS), Back Propagation Network (BPN), Meta-heuristic techniques take time of the order of several seconds to process a frame, the proposed algorithm consumes only a few milliseconds. Thus, it is well suited for the real-time watermarking of compressed videos. Highlights • A Novel Fuzzy Frame Selection based Watermarking Scheme. • MPEG-4 AVC Videos are used for watermark embedding. • Watermarking is performed in compressed domain. • An incremental variant of Extreme Learning Machine is used. • The watermarking parameters are well optimized. [ABSTRACT FROM AUTHOR]

Data security is currently become a serious concern in wireless communication system for both the users and providers. Without a secure medium, the data transmission is exposed to various types of wireless attacks. Therefore, this paper focuses on the development of a high performance parallel-pipelined-memory-based (P2M) Blowfish as a security design with reduced field programmable gate array (FPGA) utilization, which is the best security design to be embedded in the mobile devices. Through FPGA platform, the performance of the proposed Blowfish shows that a throughput increases by 10.5%, with the hardware utilization and power consumption decrease by 3.5% and 21%, respectively. The P2M Blowfish was validated in two-way communication channel by using FPGA-based radio platform together with ZigBee technology and the real-time transmission was measured in terms of bit-error-rate, received power and communication range. These characteristics have proven that the proposed P2M Blowfish possesses the ability to replace the advanced encryption standard which is known as a complex algorithm employed by most of the wireless communication standards. [ABSTRACT FROM AUTHOR]

Cooperative communication plays an important role in wireless networks by improving network connectivity, spectrum efficiency, power, and communication reliability. Moreover, cooperative communication also facilitates the development of a well-organized approach in order to improve the quality of wireless terminals. Besides, it enables the utilisation of communication resources by allowing the nodes and pathways in a network to cooperate with one another via data transmissions. To control a wireless network, cooperative communication must manage its power to improve a network’s energy efficiency, capacity and reliability. When information is transmitted at a higher power, this decreases the lifespans of both the nodes and the network itself. Thus, controlling over the transmission of power is essential to obtain a sufficient level of bit-error-rate (BER) performance at the receiver. Relay nodes can improve system performance by reducing power consumption. Moreover, the decode-and-forward method is one of the best cooperative relay protocols that can be used to achieve better system performance in power constraints and BERs. In the present paper, system model containing source, destination and relay node is analysed. One cooperative scheme which including decode and forward is employed and investigated. At the experimental and simulation levels, the present paper showed that the power in the transmitters was observed and calculated in order to show the savings which are resulting from the use of relay nodes. [ABSTRACT FROM AUTHOR]

A novel advanced modulation format based on Manchester signalling is proposed and assessed for high‐speed optical communication systems. The new advanced modulation format known as modified Manchester derived from the combination of Manchester and vestigial sideband (VSB) techniques. Its performance assessed and compared in terms of spectral efficiency, chromatic dispersion tolerance and receiver sensitivity against conventional Manchester, return‐to‐zero (RZ) and non‐RZ (NRZ) (with the same spectral width). The optimisation of the optical filter that performed the VSB filtering on the Manchester signal and its detuning frequency results in the compression of the spectral width of the Manchester signal and thereby enhanced the spectral efficiency of the modified Manchester to about 31.3%. This results in the improvement of dispersion tolerance to ∼140 ps/nm. In comparison with conventional modulation formats, the proposed system can improve the dispersion tolerance by three times more than conventional Manchester, which is 44 ps/nm, and twice more than NRZ, which is 51.8 ps/nm and has a better dispersion tolerance of 31 ps/nm than RZ with dispersion tolerance of 109 ps/nm at a bit‐error‐rate of 10−9. The improvement in the proposed modulation performance achieved without utilisation of any dispersion compensation module or electronic equalisation. [ABSTRACT FROM AUTHOR]

As data centers evolve to sustain the economic scale in network traffic, optical interconnections are adapted to support the vast amount of capacity requirements. Among emerging solutions is the incorporation of digital-signal-processing (DSP) functionalities at the receiver to compensate for the optical fiber and optoelectronic components impairments. The bottleneck in such architecture is often implementing a high-resolution and high-speed analog-to-digital-converter (ADC) device, which usually leads to massive power consumption and high costs. In this paper, we propose novel transmission schemes based on low-resolution ADCs, termed DSP-enhanced analog-to-digital conversion. The proposed methods are based on the mathematical principle of predictive quantization, combined with linear equalization theory. Mathematical analysis and performance bounds associated with common channel impairments are derived. Simulation results demonstrate that the DSP-enhanced ADC provides a significant signal-to-noise-ratio (SNR) gain and, subsequently, may enable heavy digital compensation with reduced-resolution ADCs.

In this paper, we develop the optimal relay design for multiple-input multiple-output (MIMO) multi wireless relaying networks, when we consider the problem of zero-forcing processing is studied for multi-input multi- output multi-relay communication system in which MIMO source-destination pairs communicate simultaneously. It is assumed that due to severe shadowing effects which communication links can be established only with the aid of relay node. The aim is to design the relay amplification matrix to maximize the achievable communication sum- rate through the relay, which in general amplifying-and- forward relaying mechanisms are considered. The zero forcing (ZF) algorithm has studied for a MIMO multi relay network by comparing its performance in terms of bit- error-rate (BER) at destination algorithm. In particular, we investigate its performance with and without using the ZF at the relay. Our results demonstrate that the system performance can be significantly improved by using the ZF algorithm at relay (optimal relay ZF algorithm)

DVB-T2 (Digital Video Broadcasting Terrestrial Second Generation) reception requires a sufficient quality of the received signal. CNR (carrier-tonoise ratio) and BER (bit-error-rate) are two of quantities describing the quality. This paper presents the range of each quantity providing a successful reception based on real data obtained by field-measurements. This data was collected from MO (mobile-outdoor) and SI (stationary-indoor) receivingsystems capturing signal sent by some on-air trial transmitters broadcasting services focused on the fixed-receivers. The result indicated that the successful and failed receptions were split into two quite separated (concentrated) ranges of post-decoded BER and therefore a boundary distinguishing them could be prominently defined. In contrast, they were spread in a wide common range of CNR and pre-decoded BER. Furthermore, the boundary that corresponded to this last quantity was ambiguous. In the case of MO reception as numerical examples, the two split ranges of postdecoded BER were less than about 10-5 and more than about 2.7 × 10-4 for the successful and failed receptions, respectively, whereas CNR as high as about 14 dB could be viewed as a soft boundary distinguishing these both reception-success conditions. [ABSTRACT FROM AUTHOR]

Ultra-wideband is a wireless technology arisen for future high speed multimedia applications. It can provide data rate in excess of Gigabits per second by transmitting impulse signal through the free space. However, the ultra-wideband indoor channel models proposed by the IEEE P802.15.3a suffer long multipath propagation. Due to this multipath effect, several studies have been done to improve the bit-error-rate performance of the ultrawideband system in the existence of severe interference. Yet, most of the proposed algorithms were formulated based on the Gaussian distribution, which is not true in ultra-wideband. In this paper, we first analyze the statistical behavior of the CDMA-UWB signal by applying the Kullback-Leibler divergence index. Based on the analysis, a non-Gaussian equalizer is developed by deriving an enhanced bit-error-rate optimization algorithm using the Generalized Gaussian approach. The proposed equalizer has been shown to achieve a performance gain of at least 1.5dB to 2dB over the other equalizers simulated under IEEE P802.15.3a channel models. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) has been proposed as a promising and efficient solution to indoor ubiquitous broadband connectivity. In this paper, non-orthogonal multiple access, which has been recently introduced as an effective scheme for fifth generation (5G) wireless networks, is considered in the context of VLC systems under different channel uncertainty models. To this end, we first derive a novel closed-form expression for the bit-error-rate (BER) under perfect channel state information (CSI). Capitalizing on this, we then quantify the effect of noisy and outdated CSI by deriving a simple and accurate approximation for the former and a tight upper bound for the latter. The offered results are corroborated by respective results from extensive Monte Carlo simulations and assist in developing useful insights on the effect of imperfect CSI knowledge on the overall system performance. Furthermore, it was shown that while noisy CSI leads to slight degradation in the BER performance, outdated CSI can cause considerable performance degradation, if the order of the users’ channel gains change due to the involved mobility. [ABSTRACT FROM PUBLISHER]

Busbar distribution system is used as a modular infrastructure to carry electrical energy in low voltage grid. Due to the widespread usage in industrial areas, the power line communication possibilities should be investigated in terms of smart grid concept. This paper addresses modeling of the busbar distribution system as a transmission line and gives some suggestions on the link performance for narrowband power line communication for the first time in literature. Firstly, S-parameters of different current level busbars were measured up to 500 kHz for all possible two-port signal paths. The utilization of the frequency-dependent model was proposed to extract transmission line characteristics to eliminate the unwanted measurement effects. Particle swarm algorithm was used to optimize the model parameters with a good agreement between measured and simulated S-parameters. Additionally, link performance of busbar distribution system as a power line communication channel at 3 kHz-148.5 kHz band was examined for frequency shift keying and phase shift keying modulations under different network configurations such as varying busbar type, the line length between transmitter and receiver, branch number, and terminating load impedance. Obtained results were presented as bit-error-rate vs. signal to noise ratio graphs. [ABSTRACT FROM AUTHOR]

In this paper it is investigated the non-coherent demodulation of the 2PPM modulated UWB signal, based on energy-detection. This type of demodulation leads to a simple receiver architecture, low power consumption and the benefit of multipath energy capture. However, this technique is very sensitive to noise and channel interference. To minimize this drawback, optimizations have been proposed with respect to the reduction of the integration windows size and bandwidth of input matched filter. An appropriate ultra-wideband multipath channel model such as IEEE 802.15.3a may be considered for this optimization process. Basic method uses a single integration window with a constant gain, capturing only significant useful power of the signal replicas presented in the front of the received signal, and neglecting later signal. Instead of a rectangular integration window, it is proposed to use an integration window with a linear descending gain. This may be simply obtained by adding a supplementary integration block. In this way, the front-side useful signal power is integrated with a better gain in comparison with later, predominant noise, received signal. The simulations show an improvement in bit error rate performance relative to the basic method of energy-detection.

In this paper, we propose a compressive sensing (CS)-based channel estimation technique for asymmetrically clipped optical-orthogonal frequency division multiplexing (ACO-OFDM) visible light communications (VLC) in 5G systems. We proposed a modified version of sparsity adaptive matching pursuit (SAMP) algorithm which is named as self-aware step size sparsity adaptive matching pursuit (SS-SAMP) algorithm. It utilizes the built-in features of SAMP and with additional ability to select step size according to the present situation, hence term self-aware, can provide better accuracy and low computational cost. It also does not require any prior knowledge of the sparsity of the signal which makes it self-sufficient. CS-based algorithms such as orthogonal matching pursuit (OMP), SAMP, and our proposed SS-SAMP were implemented on ACO-OFDM VLC. The paper is supported by simulation results which demonstrate performance of proposed scheme in terms of bit error rate (BER), mean square error (MSE), computational complexity, and key VLC parameter (LED nonlinearity, shot noise, thermal noise, channel response, and peak-to-average power ratio (PAPR). It is shown that the SS-SAMP is a good candidate for ACO-OFDM-based VLC that are mobile and have limited processing power, based on its performance and computational complexity. [ABSTRACT FROM AUTHOR]

Following a study on the optimal write head design for perpendicular magnetic recording, this paper aims at optimizing the design of write head for shingled magnetic record by applying the Taguchi method and the response surface methodology. The criteria for the evaluation of the write head design are to maximize the signal-to-noise ratio (SNR) and minimize the bit error rate (BER) in the shingled magnetic recording (SMR). In this paper, the magnetic fields of the write head designs are modeled using finite-element analysis, the SMRs are simulated by applying micromagnetic modeling based on Landau–Lifshitz–Gilbert equation, and the SNR and the BER are characterized using the grain flipping probability model. An optimal design of the write head is obtained to achieve the maximum SNR and the minimum BER. A discussion on the erasure band width is also carried out in this paper. Furthermore, the SNR and the BER at different bits and track densities in SMR are compared and discussed. [ABSTRACT FROM PUBLISHER]

This paper relates to development of a novel generic transceiver module for software defined radio (SDR) built using graphical user interface language LabVIEW. The main advantage of the module is that it is built entirely on the user input interface where the users get the flexibility to change any parameters according to their needs and the generic module supports there digital modulation schemes with two forward error correction coding techniques where the user has the flexibility to decide about the same. The SDR module has been fully implemented and it has the ability to navigate over a wide range of frequencies with programmable channel bandwidth and modulation characteristics. The module has been tested on real time data, text and image transmissions using the test jig for Wi-Fi module. With the help of the Wi-Fi hardware test jig it has been proved that the signal transmitted has been recovered with very low probability of error at the destination. A plot between bit error rate (BER) and the signal to noise ratio shows that a low BER has been achieved using this design. The novelty of this design is that the module auto identifies the best available digital multistate modulation scheme i.e. M-ary quadrature amplitude modulation, M-ary frequency-shift keying, M-ary phase-shift keying for the selected input. [ABSTRACT FROM AUTHOR]

In this work we analytically investigate optimal combiners for pre-amplified diversity receivers that operate under medium-tostrong atmospheric turbulence. We first demonstrate that the combiner performance is strongly affected by the existence of a signal-amplified spontaneous emission beat noise at the output of the photodetector. Due to the signaldependent nature of noise, the optimal combiner can be classified as a hybrid one, of which performance is between the well-known equalgain and maximal-ratio combiner architectures. Having established the optimal design, we further assess the proposed combiner performance over gamma-gamma and negative-exponential fading environments. [ABSTRACT FROM AUTHOR]

Channel estimation error, which adversely affects the performance of any wireless communication system, is inevitably available in receivers. However, its impact on the bit error rate (BER) performance of relay selection in underlay cognitive networks has not been investigated analytically. This paper fills in this literature gap by firstly proposing an exact single-integral form BER formula for general network topology. Based on this proposal, we further analyze the diversity gain to have insights into asymptotic performance and system design. Secondly, we derive a closed-form approximate BER formula, which has been shown highly accurate, for a typical network topology where relays are closely positioned for reduced simulation time. Various results demonstrate that the channel estimation error significantly degrades the performance of the relay selection in underlay cognitive networks and completely destroys its diversity gain. In addition, increasing the number of involved relays drastically remedies its impact. [ABSTRACT FROM AUTHOR]

Waveguide InGaAs/InAlAs avalanche photodiodes (APDs) with high bandwidths (>40 GHz) and low dark current (<50 nA at 90% of breakdown voltage) were demonstrated. The excess noise is low, corresponding to $k ~ \sim ~ 0.2$ line in the local excess noise model. Using these values bit error rate (BER) was calculated to assess the potential of our APDs. Calculated sensitivities of −21.5 dBm at 25 Gb/s and −14.2 dBm at 40 Gb/s are predicted for a BER of 10^{-10} . Analysis showed that with lower amplifier noise, the low dark current and low excess noise from our APDs are necessary to optimize the sensitivity. [ABSTRACT FROM PUBLISHER]

Long-haul high speed optical transmission systems are significantly distorted by the interplay between the electronic chromatic dispersion (CD) equalization and the local oscillator (LO) laser phase noise, which leads to an effect of equalization enhanced phase noise (EEPN). The EEPN degrades the performance of optical communication systems severely with the increment of fiber dispersion, LO laser linewidth, symbol rate, and modulation format. In this paper, we present an analytical model for evaluating the performance of bit-error-rate (BER) versus signal-to-noise ratio (SNR) in the n -level phase shift keying ( n -PSK) coherent transmission system employing differential carrier phase estimation (CPE), where the influence of EEPN is considered. Theoretical results based on this model have been investigated for the differential quadrature phase shift keying (DQPSK), the differential 8-PSK (D8PSK), and the differential 16-PSK (D16PSK) coherent transmission systems. The influence of EEPN on the BER performance in term of the fiber dispersion, the LO phase noise, the symbol rate, and the modulation format are analyzed in detail. The BER behaviors based on this analytical model achieve a good agreement with previously reported BER floors influenced by EEPN. Further simulations have also been carried out in the differential CPE considering EEPN. The results indicate that this analytical model can give an accurate prediction for the DQPSK system, and a leading-order approximation for the D8PSK and the D16PSK systems. [ABSTRACT FROM AUTHOR]

We investigate the use of 4-pulsed amplitude modulation (PAM) in reflective semiconductor optical amplifier (RSOA)-based PON implementations. The performance of low-bandwidth RSOAs can be significantly upgraded using 4-PAM together with pre-equalization. We demonstrate 4-PAM external modulation up to 8 Gb/s using a RSOA with a 3-dB bandwidth of 1.2-GHz and 10-km 4-PAM transmission at 8 Gb/s with bit-error-rate below the forward-error-correction (FEC) limit. In the full-duplex 4-PAM transmission, 10-km symmetric performance up to 4 Gb/s is experimentally demonstrated using a downstream signal with strong DC offset for data cancellation and upstream remodulation. [ABSTRACT FROM PUBLISHER]

We design and demonstrate for the first time an end-to-end binary phase-shift keying (BPSK) link based on silicon microring resonators, with an operational bit-rate at 10 Gb/s. The obtained bit-error-rate is below the forward error correction limit, validating the practical application of the demonstrated technique. Performance comparisons to conventional BPSK modulation and demodulation techniques are also made. The microring-based BPSK link promises a compact, energy efficient, and low-cost interconnect solution for high-capacity transceivers. [ABSTRACT FROM PUBLISHER]