Search

Highlights • FSO-based OCDMA PON for broadband access provisioning in remote areas is presented. • Closed-form expressions for BER, throughput, and delay are derived and analyzed. • Atmospheric turbulence and pointing errors have a serious impact on the performance. • System capacity is increased through space division multiplexing. Abstract This paper proposes and analyzes an optical code-division multiple-access (OCDMA) network based on free-space optical (FSO) links for broadband access provisioning in areas where laying down optical fiber is difficult or even impossible. Spectral-amplitude coding (SAC) category generated by a compact encoder is adopted as a coding scheme with binary ON-OFF keying (OOK) modulation and direct detection. Moreover, we employ spatial multiplexing scheme to increase the capacity of the proposed network by exploiting the unused already generated (by compact encoder) codewords at a certain acceptable bit error rate (BER) level. A closed-form average BER expression is derived under the joint impact of both turbulence-induced fading modeled by the Gamma-Gamma (Γ Γ) distribution and misalignment-induced fading, in the presence of beat noise, shot noise, and thermal noise. In addition, the data link layer performance modeled by Markov chain is evaluated in terms of achieved throughput and average packet delay by considering the effects of atmospheric turbulence and pointing errors. Our results show that both the atmospheric turbulence and the pointing errors impose a detrimental impact on the achievable throughput and average delay of FSO-based OCDMA passive optical network (PON). [ABSTRACT FROM AUTHOR]

In the paper, we introduce the 8-state trellis-coded modulation (TCM) scheme using sphere packing four-dimensional (4D) non-cubic constellations on the basis of a novel set-partitioning (SP) method. Sphere packing four-dimensional formats have a higher asymptotic power efficiency (APE) because the spatial arrangement of constellation points is more dense. The scheme can further alleviate the contradiction between spectral efficiency (SE) and APE in 4D modulation format. The SP process of 4D non-cubic constellations is completed in the condition that the minimum Euclidean distance between the constellation points and the number of nearest neighbors are adequately considered. We compared these 4D TCM formats to their corresponding 4D formats (i.e., dicyclic4_16, b4_32, b4_64, SP-QAM4_128 and 256-D 4) in the 800 km standard single-mode fiber (SSMF) transmission system. Through measurements of bit error rate (BER) performance, at the BER = 1 × 10−3, the coding gains are 5.7 dB, 3.8 dB, 3.6 dB, 3.9 dB and 4.1 dB respectively. [ABSTRACT FROM AUTHOR]

This paper describes a unified static/dynamic entropy generator based on a 512-b common entropy source (ES) array fabricated in 14-nm tri-gate CMOS with reconfigurable and adaptive post-processing circuits implemented on Arria 10 FPGA, targeted for flexible and secure privacy preserving mutual authentication on compact trusted mote platforms at the edge of internet of things. Several conditioning techniques that include temporal majority voting (TMV)-assisted ES array segregation with integrated bias tracking, three-way in-line self-calibration for tolerance to process–voltage–temperature variation, tri-level hierarchical Von Neumann (VN) extraction to maximize entropy harvesting, soft-dark bit masking for improving physically unclonable function (PUF) stability, and selective stress hardening to co-optimize the ES array for static-dynamic entropy with bias aware device aging enable simultaneous PUF and true random number generator (TRNG) operation with 1.48 and 0.56 Gb/s throughput, respectively, measured at 650 mV, 70 °C. The all-digital design with a compact layout footprint of 2114 $\mu \text{m}^{2}$ facilitates seamless integration in area constrained system-on-chips while achieving: 1) 25% area savings over conventional separate PUF and TRNG implementations; 2) cryptographic quality TRNG stream that passes all NIST randomness tests with 0.38 average p-value; 3) $1.6\times $ higher extractor performance at $9\times $ lower area with 750-gate hierarchical VN circuit over conventional light-weight entropy extractors; 4) 0.9996/0.99997 static/dynamic Shannon entropy indicating unbiased PUF/TRNG streams; 5) ultra-low energy consumption of 2.5 and 0.46 pJ/bit measured at 650 mV, 70 °C in TRNG and PUF modes; 6) 40% higher TRNG throughput with three-way self-calibration featuring coarse-grain column swap, fine-grain incremental ES substitution, and residual entropy recycling; 7) resistance to power injection attacks as measured by 64% higher performance over un-calibrated design in the presence 200-mV supply noise; 8) 2.8% PUF bit-error measured at 0.55–0.75 V, 25 °C–110 °C with 15-way TMV and soft dark-bit masking over a window of 100 cycles; 9) $14.8\times $ inter and intra-PUF hamming distance separation; and 10) 56% reduction in discarded ES cells with selective stress hardening to opportunistically reinforce/nullify pre-existing bias in PUF/TRNG candidate cells. To our knowledge, this is the first reported unified PUF-TRNG implementation enabling simultaneous generation of high-entropy chip-ID and encryption keys in real time. [ABSTRACT FROM AUTHOR]

Abstract With the continuous development of wireless networks, energy conservation and energy efficiency are becoming key factors in improving the network lifetime. In multi-antenna wireless networks, the energy conservation problem can be addressed using the trade-off between the transmit power and the circuit energy consumption. In this paper, we propose a cross layer protocol, MAC-LEAP, that selects the best transmission policy based on Multiple-Input Multiple-Output (MIMO) in both single-hop and multi-hop wireless networks. Various data transmission algorithms are presented in which many factors are considered in order to find the best transmission policy between each pair of nodes. An RTS/CTS handshake is used to exchange the required information to select the best transmission policy prior to data transmission. Moreover, we introduce a MIMO-based framework in Network Simulator 3 (ns-3) in which the wireless nodes may be equipped with more than one antenna. Using extensive simulations in ns-3, we compare the performance of MAC-LEAP with traditional protocols in terms of the network lifetime and the number of received packets. The simulation results show that MAC-LEAP outperforms the traditional protocols in both single-hop and multi-hop networks for various transmission distances and target Bit-Error-Rates (BER). [ABSTRACT FROM AUTHOR]

This paper investigates the constellation/codebook design of a promising uplink multiple access technique, sparse code multiple access (SCMA), proposed for the fifth generation mobile networks. The application of bit-interleaved coded modulation with iterative multiuser detection is considered for uplink SCMA over fading channels. Extrinsic information transfer chart is used to aid the analysis and the design of multidimensional constellations, and the design criteria for multidimensional constellations and labelings optimization are thus established. Furthermore, a new and simple approach of multi-stage optimization for the multidimensional constellation design is proposed for SCMA, to improve the bit-error rate performance and alleviate the complexity of turbo multiuser detection. Numerical and simulation results are also provided to demonstrate the performance and verify the efficiency of the proposed scheme, compared with the state of the art. [ABSTRACT FROM AUTHOR]

Summary: High‐data transmission rate and reliable communication in underwater acoustic channel is challenging because of limited bandwidth, multipath propagation, and Doppler shift, which results in poor bit error performance. Under this constraint, this paper explains the simulation results of underwater wireless acoustic data transmission system by using quadrature phase shift keying modulation with convolution encoder at the transmitter and proposed Viterbi decoder at the receiver. The decoder algorithm in comparison with MATLAB inbuilt function shows asserting improved results. This paper evaluates the performance of convolution coded orthogonal frequency division multiplexing modem, which is studied over typical underwater channel through an extensive computer simulation and a semirealistic experimentation. The performance of convolution coded orthogonal frequency division multiplexing system is measured in time domain plots, bit error rate curves, and number of bit errors per frame over additive white Gaussian noise and Rayleigh channel conditions. [ABSTRACT FROM AUTHOR]

The exponential growth of the demand for broadband services has imposed great challenges on the design of spectrum-efficient optical transmission system in Passive Optical Network (PON). Recently, an innovative Orthogonal Frequency Division Multiplexing (OFDM) scheme, called Polar-OFDM (P-OFDM), has emerged as a promising solution to boost the spectral efficiency of optical transmission in PON. However, the traditional P-OFDM does not yet perform best in spectral efficiency as it only uses half of the total subcarriers. In this paper, we verify a promising complementation between Polarization Multiplexing (POLMUX) and P-OFDM aiming at higher spectral efficiency. We then propose the full-subcarriers P-OFDM by loading data on the even-indexed subcarriers of X polarization and the odd-indexed subcarriers of Y polarization, respectively. Thus, all of the subcarriers will be utilized for effective data transmission, which can double the spectral efficiency. More importantly, because the subcarriers are interlaced on different polarizations, the cross-polarization interference can be significantly mitigated, which enables the independent channel estimation and equalization at the receiver to recover the data carried on each polarization. Our evaluation results demonstrate that the proposed system realizes the double spectral efficiency of the traditional P-OFDM with reasonable Bit Error Rate (BER) performance loss. [ABSTRACT FROM AUTHOR]

In this article we have proposed a novel cost effective optical frequency comb (OFC) generator by using pair of Mach zehnder modulators (MZMs) in cascaded configuration with a single external modulated laser (EML) source, where the two MZMs were driven by low powered RF source with 30 GHz frequency by incorporating no extra electrical components. More than 60 flattened carriers were generated in cascade mode with such simplified model having high tone to noise ratio (TNR) of over 40 dB, 0.5 dB amplitude difference in most of the carriers, 30 GHz frequency spacing, and 37 dB side mode suppression ratio, all the frequency tones lies in optical C-band. The EML’s power was kept at 10 dBm while the extinction ratios (ER) were studied from 0 to 20 dB where we found that the TNR and amplitude difference of the OFC were directly connected with the ER value of EML. OFC was deployed at optical line terminal (OLT) side that decreases the costs, size, and power usage for wavelength division multiplexed passive optical network (WDM-PON). Furthermore, we utilized new setup at ONU side of WDM-PON which replaces the conventional IM-OOK with DD-MZM-NRZ. This way power consumption was reduced at ONU side by 3.5 dBm, and the receivers’ sensitivity was also improved at OLT side for the uplink transmission including the system performance. Colorless ONUs were achieved by utilizing the downlink signal’s power. In downlink transmission, OFC was deployed at OLT side of WDM-PON network where each wavelength supported 20 Gbps data based QPSK, this system is capable of 20 * 61 Gbps data transmission from 25 km to 50 km fiber span. This model could support 1.22 Tbps downlink and 610 Gbps uplink transmission effectively. The system’s performances were investigated in terms of bit error rate, power penalties, and eye patterns. The average power penalties were founded as 2.5 dBm, and 3 dBm across 25 km fiber in the downlink-uplink transmission respectively, similarly the power penalties across 50 km fiber span in downlink-uplink transmission were 4.5 dBm and 5 dBm respectively. [ABSTRACT FROM AUTHOR]

The stable operation of pulse sequence generators at high temperatures (200°C) has been an important issue for some time in the application of nuclear magnetic resonance (NMR) apparatus for oil exploration. The application of system-in-package (SiP) technology was used to improve the temperature-resist grade of the hardware platform. A pulse sequence generator that meets the requirements of accurate phase and adjustable frequency during NMR apparatus in high temperature environments was designed and implemented. At ambient temperatures of up to 200°C, experimental results show that the delay times of the rising and falling edges of the pulse are 3.2 and 3.35 ns. respectively. The eye diagram Q factor of the critical path is not less than 15, and the Bit Error Rate (BER) is not more than 10-50. The experimental results show that a pulse sequence generator can meet the requirements of high temperature NMR apparatus, and can also provide a template for the design of an NMR pulse sequence generator for special fields of application, such as deep sea surveys and aviation. [ABSTRACT FROM AUTHOR]

In this paper, two new methods to construct low-density parity-check (LDPC) codes with low error floor and large girth are proposed. The first one is APPS-LDPC codes based on Arithmetic Progression theory and cycle classification, whose girth is at least eight. Based on the designed APPS-LDPC codes, we further construct Bi-diagonal APPS-LDPC codes with column degree 4, whose circulant permutation matrix is combined by two shifted identity matrix. The designed APPS-LDPC code has 0.25 and 0.2 dB coding gain compared to partition-and-shift (PS)-LDPC code and progressive-edge-growth (PEG)-LDPC code. And the Bi-APPS-LDPC code has similar performance to T2 LDPC code in CCSDS standard, but its effective structure is more suitable for high throughput decoder implementation on FPGA. Both codes have less construction complexity than PS-LDPC code and PEG-LDPC code. [ABSTRACT FROM AUTHOR]

Spatial modulation (SM) is a simple and spectral efficient modulation technique that has received much interest recently. In this paper, an adaptive SM (ASM) scheme is presented by combining adaptive modulation with conventional SM. The performance of ASM is analyzed in spatially correlated Rayleigh fading channels. In order to reduce the computational complexity of average bit error rate (BER), an approximate expression of error probability of the antenna index estimation, which contributes one of two components of the average BER, is derived by using the fitting method and matches well with simulation results in the SNR range of interest. With the above results, the closed-form spectrum efficiency (SE) and overall average BER are obtained, respectively. Besides, the optimized switching thresholds for maximizing SE under an average BER constraint are achieved by means of the Karush Kuhn Tucker conditions, and the resultant SE performance can be improved greatly when compared to the ASM system with fixed thresholds. Simulations indicate that the theoretical SE and BER are effective and agree well with the corresponding simulations. Moreover, the SE and BER performance of ASM under spatially correlated channel are poorer than those under spatially independent channel because of the influence of spatial correlation. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the performance of underwater wireless optical multiple-input multiple-output communication system combining spatial modulation (SM-UOMIMO) with flag dual amplitude pulse position modulation (FDAPPM). Channel impulse response for coastal and harbor ocean water links are obtained by Monte Carlo (MC) simulation. Moreover, we obtain the closed-form and upper bound average bit error rate (BER) expressions for receiver diversity including optical combining, equal gain combining and selected combining. And a novel adaptive power allocation algorithm (PAA) is proposed to minimize the average BER of SM-UOMIMO system. Our numeric results indicate an excellent match between the analytical results and numerical simulations, which confirms the accuracy of our derived expressions. Furthermore, the results show that adaptive PAA outperforms conventional fixed factor PAA and equal PAA obviously. Multiple-input single-output system with adaptive PAA obtains even better BER performance than MIMO one, at the same time reducing receiver complexity effectively. [ABSTRACT FROM AUTHOR]

Advanced multi-level modulation formats have shown their great potential in high-speed and high-spectral-efficiency optical communications. Using quadrature phase-shift keying (QPSK) modulation format for free-space optical (FSO) communication, a bidirectional high-speed FSO transmission link with the bit rates of up to 40 Gbit/s over ∼ 1 km, between two buildings in the campus of Changchun University of Science and Technology, Changchun, China, is experimentally demonstrated cooperating by capture and tracking systems. The eye-diagrams and constellation diagrams of the transmitted QPSK signals are clearly observed. By comparing the bit error rate (BER) curves before and after transmission, one can find that the receiving powers are both less than −16.5 dBm for the forward and backward transmissions of the bidirectional 20, 30, and 40 Gbit/s FSO links, and their power penalties due to the phase fluctuation of the atmospheric channel are both less than 2.6 dB, at the BER of 3.8 × 10 −3 . [ABSTRACT FROM AUTHOR]

In an underwater wireless optical communication (UWOC) link, power fluctuations over finite-sized collecting lens are investigated for a horizontally propagating Gaussian beam wave. The power scintillation index, also known as the irradiance flux variance, for the received irradiance is evaluated in weak oceanic turbulence by using the Rytov method. This lets us further quantify the associated performance indicators, namely, the aperture averaging factor and the average bit-error rate (). The effects on the UWOC link performance of the oceanic turbulence parameters, i.e., the rate of dissipation of kinetic energy per unit mass of fluid, the rate of dissipation of mean-squared temperature, Kolmogorov microscale, the ratio of temperature to salinity contributions to the refractive index spectrum as well as system parameters, i.e., the receiver aperture diameter, Gaussian source size, laser wavelength and the link distance are investigated. [ABSTRACT FROM AUTHOR]

Widespread use of white light-emitting diodes and ubiquitous smart devices offer the opportunity to establish VLC, which has become a hot research topic based on the growing number of publications over the last decade. Camera-based VLC, namely OCC, provides many unique features when compared to a single-photodiode-based system, such as the ability to separate incident light in the spatial and color domains. OCC technology represents a promising approach to utilize the benefits of VLC in beyond-5G scenarios and is one of the key technologies of the Internet of Things. Establishing a long communication channel in OCC, as well as non-flickering illumination by using low-frame-rate camera detectors, requires special modulation schemes. This article provides an overview of the principles of three categories of modulation schemes for OCC systems using a low-frame-rate camera detector. In addition, a series of undersampled modulation schemes are proposed and discussed to achieve flicker-free OCC with higher spectral efficiency. In addition, framing structures are designed to solve problems occurring in OCC systems using particular modulation schemes. To evaluate the performance of these modulation schemes, measured bit error rate values are shown. Finally, challenges in the implementation of OCC systems are also outlined. [ABSTRACT FROM AUTHOR]

Several power allocation algorithms for cooperative relay networks are presented in the literature. These contributions assume perfect channel knowledge and capacity achieving codes. However in practice, obtaining the channel state information at a relay or at the destination is an estimation problem and can generally not be error free. The investigation of the power allocation mechanism in a wireless network due to channel imperfections is important because it can severely degrade its performance regarding throughput and bit error rate. In this paper, the impact of imperfect channel state information on the power allocation of an adaptive relay network is investigated. Moreover, a framework including Automatic Repeat reQuest (ARQ) mechanism is provided to make the power allocation mechanism robust against these channel imperfections. For this framework, the end-to-end SNR is calculated considering imperfect channel knowledge using ARQ analytically. The goal is to emphasize the impact of imperfect channel knowledge on the power allocation mechanism. In this paper, the simulation results illustrate the impact of channel uncertainties on the average outage probability, throughput, and consumed sum power for different qualities of channel estimation. It is shown that the presented framework with ARQ is extremely robust against the channel imperfections. [ABSTRACT FROM AUTHOR]

In this paper, the problem of joint estimation of carrier and sampling frequency offsets is considered, for IEEE 802.11ac-based OFDM wireless LAN systems, based on the guard interval and two long symbols (GI2L) in the preamble of a packet. The measurement model of the GI2L is developed, in the presence of both carrier and sampling frequency offsets. One method based on the GI2L is proposed and compared with some existing relevant methods based on long symbol/data symbols. An improved performance, measured by estimation error and bit error rate, is achieved by this method, at a similar computational load. [ABSTRACT FROM AUTHOR]

Today's wireless communication systems are highly susceptible to malicious jamming attacks and interference signals. These attacks are sent via communication link at the same frequency as the intended signal. The sent information is thus corrupted and the receiver is unable to correctly decode the sent data stream. This paper thereby seeks to come up with an anti-jamming system that is able to respond intelligently to such malicious attacks, block them and enable the correct decoding of a message. The proposed system objectives are to ensure that data throughput is at its highest, energy consumption at the lowest level and the bit error rate is maintained at a very low level during and after any jamming attack. The system is also able to identify jammer state from transmit power and respond accordingly. [ABSTRACT FROM AUTHOR]

The universal filtered multicarrier (UFMC) is an appealing technique to eliminate out-of-band emission (OOBE) for fifth-generation (5G) networks. However, its signals that are modulated to the carriers, which are on the edges of one subband, are influenced by the filter. In this paper, an interference cancelation scheme is proposed to suppress the interference and to improve the multiuser system performance. Here, interference cancelation subcarriers are inserted on the edges to reduce the filter interference. This scheme ensures that the operating subregion or subband supports the variable bandwidth allocation to meet the requirements of 5G networks. Simulation results show that the bit error rate (BER) performance improves by 4 and 7 dB compared with that of the conventional UFMC when the corresponding Eb/N0 is 15 and 20 dB. Comparisons with both the standard OFDM and the GB OFDM are also reported. The results demonstrate that the proposed UFMC scheme outperforms the other two systems, especially compared with the GB OFDM system under the condition of the same spectral efficiency. [ABSTRACT FROM AUTHOR]

A combined analysis of transient simulation and statistical method is proposed for comparative study of signalling methods applied to high-speed backplane transceivers. This method enables fast and accurate signal-to-noise ratio and symbol error rate estimation of a serial link based on a four-dimension design space, including channel characteristics, noise scenarios, equalisation schemes, and signalling methods. The proposed combined analysis method chooses an efficient sampling size for performance evaluation. A comparative study of non-return-to-zero (NRZ), PAM-4, and four-phase shifted sinusoid symbol (PSS-4) using parameterised behaviour-level simulation shows PAM-4 and PSS-4 has substantial advantages over conventional NRZ in most of the cases. A comparison between PAM-4 and PSS-4 shows PAM-4 gets significant bit error rate degradation when noise level is enhanced. [ABSTRACT FROM PUBLISHER]

This paper proposes a general iterative demapping–decoding approach for two-way relay (TWR) communications with physical-layer network coding, where the relay node performs decode-and-forward. The bit-interleaved coded modulation (BICM) with high-order quadrature amplitude modulation is considered. The iterative decoding, namely the BICM-ID for TWR channels, is introduced. Based on a joint trellis, BICM-ID estimates the end nodes’ coded bits, leading to an estimation of the transmitted symbol pair probability, which is crucial for achieving iterative decoding gains in bit error rate (BER). The end nodes’ constellation design criterion is proposed to optimize the BICM-ID performance over the TWR fading channel. The EXtrinsic Information Transfer analysis is also performed, showing the iterative system's convergence behavior and providing information on code design. Our simulation results show the proposed BICM-ID scheme can achieve significant performance gains, yielding an asymptotic tendency of approaching the cut-set BER performance limit. [ABSTRACT FROM PUBLISHER]

In this paper, we evaluate the uplink bit error rate (BER) of multicarrier-code-division-multiple-access (MC-CDMA) cellular systems with multiuser-maximum-likelihood detector (MU-MLD). The scenario considers perfect power control, own-cell interference (or multiple access interference—MAI), interference from co-cells (or co-cell interference—CCI), additive white Gaussian noise, exponential path-loss and slow frequency-selective Rayleigh fading. Upper bound expressions to evaluate the mean BER are obtained, which are functions of the signal-to-noise ratio (SNR), the number of users, the spreading factor, and the channel reuse factor. For BPSK and 4-QAM (quadrature amplitude modulation), closed-form expressions involving the analytical calculation of pairwise error probabilities are obtained. For 16-QAM and 64-QAM, we show that the number of pairwise error probabilities needed to obtain the BER can be simplified through the constellations symmetry. The procedure for obtaining this simplification is detailed. Also, by considering BER asymptotes, expressions for the SNR penalty due to MAI are derived. Monte Carlo simulations verify the analytical expressions accuracy. In the simulations, the MU-MLD is implemented through the sphere decoder algorithm with MMSE QR factorization. Results show that MC-CDMA does not lose diversity due to MAI. Moreover, CCI significantly affects the system performance. As a consequence, it produces floors in the BER curves. [ABSTRACT FROM PUBLISHER]

The performance of a free-space optical communication system is highly affected by the atmospheric turbulence in terms of scintillation. An optical communication system based on intensity-modulation direct-detection was built with 1-km transmission distance to evaluate the bit error rate (BER) performance over real atmospheric turbulence. 2.5-, 5-, and 10-Gbps data rate transmissions were carried out, where error-free transmission could be achieved during over 37% of the 2.5-Gbps transmissions and over 43% of the 5-Gbps transmissions. In the rest of the transmissions, BER deteriorated as the refractive-index structure constant increased, while the two measured items have almost the same trend. [ABSTRACT FROM AUTHOR]

Reliable energy efficient information transmission is the primary design objective of a Wireless Sensor Network (WSN), considering its unique energy and resource constraints. Energy efficiency and bit error rate (BER) performance are the basic criteria to be taken into account while designing an optimal error correction scheme for WSNs. In this paper, a novel energy efficient error control scheme is proposed which minimizes the energy overheads of a typical error control scheme such as additional bits' transmit energy and encoding/decoding energy, while achieving a better BER performance compared to the standard schemes. The redundant bits' transmit energy is saved by incorporating compression and coding energy is minimized by employing simpler operations compared to other schemes. Further,the proposed scheme is validated in the context of mica2 motes. The BER performance and energy consumption of the presented scheme are studied and compared with standard error control schemes,such as, Hamming (7, 4) and RS (31, 29). Simulation results demonstrate the efficacy of the proposed methodology yielding a coding gain (CG) of 4.093 dB with a parameter selection of {30, 7, 2, 5}, in AWGN channel at BER of $$10^{-5}$$ , as compared to CG of 0.561 dB and 1.485 dB obtained using Hamming (7, 4) and RS (31, 29), respectively. Further, the standard codes above have a redundancy of 75% and 6.9% respectively while the proposed code with the above parameters achieves a compression of 23.81%. Quantification of energy consumption corresponding to each of the above schemes is also provided to prove the energy efficiency of the proposed technique. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of the obtainment of the theoretical bit error rate (BER) performance in single-input-single-output and multiple-input-multiple-output systems with single-carrier with frequency-domain equalization modulations and iterative receivers based on the iterative block decision feedback equalization concept. Through the consideration of a Gaussian-based approach to obtain the BER performance, we present a simple and accurate model to improve such method by compensating the difference between the theoretical performance results and the ones obtained by simulation. [ABSTRACT FROM AUTHOR]

The mean spectral efficiency of the uplink of MC-CDMA cellular systems is evaluated. The complete system employs the multicarrier-code division multiple access (MC-CDMA) technique, a linear antenna array at the base stations, frequency interleaving, maximal ratio combining, adaptive modulation, perfect power control and a cyclic prefix large enough to eliminate the intersymbol and intercarrier interferences effects. This scenario assumes the presence of multiple access interference, co-channel interference, additive white Gaussian noise, exponential path-loss and slow and frequency selective Rayleigh fading channel. In this context, a procedure to calculate the mean spectral efficiency of the cellular network is proposed, which depends of the mean bit error rate, the channel reuse factor, the increase of bandwidth due to the cyclic prefix, the system load, the spreading factor, the cell radius and the modulation schemes. Results show that an unitary channel reuse factor is the most efficient way to use the spectrum, but it is critical in relation to the transmission rates. Also, as orthogonal frequency division multiple access technique is a particular case of MC-CDMA, the spectral efficiency of both techniques is compared. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a novel peak to average power ratio (PAPR) reduction scheme for the DC-biased optical orthogonal frequency division multiplexing visible light communications (DCO-OFDM) systems. We implement the Gaussian matrix multiplication method to reduce the high PAPR of the DCO-OFDM system at the transmitter and use the back propagation (BP) algorithm to recover the original OFDM frame at the receiver. The simulation results show that the proposed scheme can achieve a PAPR 0 reduction by about 3 dB for 128-subcarrier DCO-OFDM systems, and a nearly identical bit error rate (BER) performance to the ideal OFDM system with no distortion. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of an optical system based on optimized semiconductor optical amplifier (SOA) at 160 Gbps with 0.8nm channel spacing. Transmission distances up to 280km at -30dBm input signal power and up to 247 km at -32dBm input signal power with acceptable bit error rate (BER) and Q-factor are examined. It is also analyzed that the transmission distance up to 292km has been covered at -28 dBm input signal power using Dispersion Shifted (DS)-Normal fiber without any power compensation methods. [ABSTRACT FROM AUTHOR]

In this paper we briefly describe the design, implementation, and evaluation of a novel adaptive optimization approach for the feed-forward software defined equalization (FFSDE) method using the least mean squared (LMS) algorithm. In our design, we adaptively change the filter length ( N) and step size ( $$\mu$$ ) to achieve the optimal bit error rate value. We used a vector signal generator RF PXI-5670 and a vector signal analyzer (VSA) RF PXI-5660 to test the validity of our approach. We implemented our method for the M-ary quadrature amplitude modulation (M-QAM) scheme in the VSA (which served as a receiver). The experimental results showed that we achieved high convergence speed and accuracy for rapidly changing transmitter channel characteristics. The automatic optimal setting feature of the LMS Algorithm parameters N and $$\mu$$ , enabled us to solve the hardware configuration problem for the FFSDE method. Determination of the LMS Algorithm training sequence size for the particular M-QAM allowed us to eliminate redundant data of the training sequence and increase the throughput. [ABSTRACT FROM AUTHOR]

This paper provides the detailed simulation analysis of Filter Bank Multicarrier Cognitive Radio for doing tradeoff between the parameters of cognitive radio for achieving optimum performance. An attempt for tradeoff between different transmission-radio environment parameters has been done as this leads to an increase in spectrum efficiency by decreasing the spectral leakage which provides optimal performance. The optimization-tradeoff between different radio environment parameters is necessary for prediction and planning of future wireless communication systems. Transmission, reception and radio environment parameters play a key role in the performance enhancement of FBMC cognitive radio. [ABSTRACT FROM AUTHOR]

In orthogonal frequency division multiplexing (OFDM) system, high value of peak-to-average power ratio (PAPR) is an operational problem that may cause non-linear distortion resulting in high bit error rate. Selected mapping (SLM) is a well known technique that shows good PAPR reduction capability but inflicts added computational overhead. In this paper, using Riemann sequence based SLM method, we applied reverse searching technique to find out low PAPR yielding phase sequences with significant reduction in computational complexity. Additionally, we explored side-information free transmission that achieves higher throughput but sacrifices PAPR reduction. Finally, to overcome this loss in PAPR reduction, we proposed application of Square-rooting companding technique over the output OFDM transmitted signal. Simulation results show that the proposed method is able to compensate the sacrifice in PAPR and achieved PAPR reduction of 8.9 dB with very low computational overhead. [ABSTRACT FROM AUTHOR]

In this paper, the performance analysis of atmospheric optical communications links is analyzed in terms of the average bit error rate. To this end, the optical irradiance scintillation due to the turbulence effects is modeled by a generalization of the Málaga or $${\mathcal {M}}$$ distribution. In particular, the behavior of the atmospheric optical channel is treated as a superposition of a finite number of Generalized-K distributed sub-channels, controlled by a discrete Negative-Binomial distribution dependent on the turbulence parameters. All previous results derived until now were restricted to natural numbers for those turbulence parameters. Here, new analytical formalisms for evaluating the average bit error rate performance are proposed. These formalisms are based on considering the most accurate scenario in which such turbulence parameters are extended to real numbers. Theses new expressions are a valuable tool for analysing the performance of atmospheric optical links. [ABSTRACT FROM AUTHOR]

Energy-efficient transmission is fast becoming a critical factor in designing future mobile broadband cellular communication systems. This research work examines the constraints with regard to the achievable throughput and energy efficiency that can be attained on the use of precoding-based massive MIMO systems, bearing in mind the effect of some key performance impacting parameters. We first introduced an absolute energy efficiency-based model to evaluate the deep-down relationship among the packet length, the Bit error rate (BER) and throughput. Then, by means of simulation with cyclic coordinated search algorithm, optimal achievable throughput and energy efficiency performance have been shown and demonstrated for variable capacity of users and number of transmission antennas. This work is expected to be of enormous importance to practical system design on the use of massive MIMO antenna technology for data throughput and energy efficiency maximization in future 5G systems. [ABSTRACT FROM AUTHOR]

The average bit-error-rate ( BER ) performances of asymmetrical optical Gaussian beams propagating in oceanic and marine atmospheric turbulence are examined. Both type of media are assumed to exhibit weak turbulence. The effect of asymmetry factor on the BER performance are investigated in conjunction with the oceanic turbulence parameters of the ratio of temperature to salinity contributions to the refractive index spectrum, the rate of dissipation of mean-squared temperature and the rate of dissipation of kinetic energy per unit mass of fluid, and with the marine atmospheric link parameters of the link length and the structure constant. Also, the variations of the BER against the source size of various asymmetrical beams are scrutinized in both oceanic and marine atmospheric media. [ABSTRACT FROM AUTHOR]

This work studied the offset tolerance (OT) with a particular focus on the angular deflection of an orbital angular momentum (OAM) system in free space. We derived an analytical expression of the OT for an angular-deflected Laguerre-Gaussian (LG) beam via Fourier series (FS) expansion and determined the upper bound of the OT for OAM-multiplexed systems. Next, we analyzed the effects of the beam waist, transmitted distance and OAM state number on the OT numerically. The calculation results indicate that the OT of the deflected beam is inversely proportional to the square root of the OAM number and approximately reciprocal to the propagation distance. Finally, we calculated the bit-error rate (BER) and aggregated capacity of multiplexed systems with different sets of channels. The results confirmed that the estimated upper bound is reasonable, especially for larger mode spacings. This work can provide guidance for the design and optimization of angular-deflected OAM-multiplexed communication systems. [ABSTRACT FROM AUTHOR]

Wireless Body Area Networks (WBANs) is a technology that has revolutionized the health-care industry by allowing remote monitoring, early detection and prevention of diseases. Patients can be remotely monitored thanks to implant devices in the body or by placing nodes on different parts of the body. Often the deployed sensor nodes are constraint by limited battery sources and are required to continuously collect the data and transfer it to the sink node, thus requiring energy efficient communication schemes. In addition, in poor channel conditions, this data collection and transfer results in retransmission thus wasting useful energy. This work presents a cooperative network coding based transmission technique for spectrum and energy efficiency in WBANs. The bit error rate (BER) of the network coded path in comparison to direct communication approach is explored. The effect of WBAN path loss due to different node positions is also discussed. It is observed that node position greatly affects path loss and received power which in turn affect the BERs. Simulation results show that network coded cooperative communication strategy in WBAN channel with and without combining outperforms as compared to direct communication. [ABSTRACT FROM AUTHOR]

This work studies the performance of a cooperative network which consists of two channel-coded sources, multiple relays, and one destination. To achieve high spectral efficiency, we assume that a single time slot is dedicated to relaying. Conventional network-coded-based cooperation (NCC) selects the best relay which uses network coding to serve the two sources simultaneously. The bit error rate (BER) performance of NCC with channel coding, however, is still unknown. In this paper, we firstly study the BER of NCC via a closed-form expression and analytically show that NCC only achieves diversity of order two regardless of the number of available relays and the channel code. Secondly, we propose a novel partial relaying-based cooperation (PARC) scheme to improve the system diversity in the finite signal-to-noise ratio (SNR) regime. In particular, closed-form expressions for the system BER and diversity order of PARC are derived as a function of the operating SNR value and the minimum distance of the channel code. We analytically show that the proposed PARC achieves full (instantaneous) diversity order in the finite SNR regime, given that an appropriate channel code is used. Finally, numerical results verify our analysis and demonstrate a large SNR gain of PARC over NCC in the SNR region of interest. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new peak-to-average power ratio (PAPR) reduction technique, which is referred to as trellis-assisted constellation subset selection (TACSS, or TAX for short), for orthogonal frequency-division multiplexing (OFDM) signals. We control the signal transition by judiciously selecting the appropriate constellation subset for PAPR reduction with the controlling bits that are subject to the trellis-based constraint imposed by a bank of memories. A novel constellation design suitable for the proposed system is also introduced. A major property offered by the proposed approach is that the controlling bits and the information bits are perfectly separable at the receiver, which leads to a simple implementation of its soft-in–soft-out (SISO) decoder for coded OFDM systems. Through the performance analysis of PAPR reduction capability, power amplifier (PA) efficiency, average mutual information (AMI), and bit error rate (BER), the achievable tradeoff relationship between the transmitter and receiver performances of the proposed system is addressed. Furthermore, performance comparisons of the proposed scheme with other major PAPR reduction schemes such as trellis shaping, discrete Fourier transform (DFT) precoding, and clipping and filtering demonstrate its practical advantage in a high-spectral-efficiency regime. [ABSTRACT FROM PUBLISHER]

Spatially coupled low-density parity-check codes can be decoded using a graph-based message passing algorithm applied across the total length of the coupled graph. However, considering practical constraints on decoding latency and complexity, a sliding window decoding approach is normally preferred. In order to reduce decoding complexity compared with standard parallel decoding schedules, serial schedules can be applied within a decoding window. However, uniform serial schedules within a window do not provide the expected reduction in complexity. Hence, we propose non-uniform schedules (parallel and serial) based on measured improvements in the estimated bit error rate (BER). We show that these non-uniform schedules result in a significant reduction in complexity without any loss in performance. Furthermore, based on observations made using density evolution, we propose a non-uniform pragmatic decoding schedule (parallel and serial) that does not require any additional calculations (e.g., BER estimates) within the decoding process. [ABSTRACT FROM PUBLISHER]

For multilevel cell (MLC) phase change memory (PCM), resistance drift (R-drift) phenomenon causes cell resistance to increase with time, even at room temperature. As a result, the fixed-threshold-retention (FTR) raw-bit-error-rate (RBER) surpasses practical ECC correction ability within hours after being programmed. This study proposes a resistance drift compensation (RDC) scheme to mitigate R-drift issue. The proposed RDC scheme realizes PCM drift compensation and features RDC pulse to suppress ECC decoding failure. The proposed approach was validated using a 90-nm 128M cells PCM chip and an FPGA-based memory controller verification system. The MLC PCM FTR RBER has been suppressed by over $100\times $ , thereby bringing it within ECC capability. The effectiveness of the RDC scheme was verified up to 10^{6} cycles. [ABSTRACT FROM AUTHOR]

In this paper, we present a method to realize wireless communication system modelling using SystemC at different levels of abstraction. The objective of the simulations is to analyze the system-level performance with considering circuit-level specifications by integrating the necessary circuit-level measurements (or Spice simulation) into the system-level models. Bluetooth Low Energy (BLE) RF Transceiver is chosen for this study. It is modelled with SystemC-AMS (SCAMS) and is integrated into a SystemC-TLM (SCTLM) described digital BLE environment to achieve a global system simulation. The simulation gives results as the RF Transceiver energy consumption and Bit-Error-Rate (BER), which can be used to analyze and optimize RF system design. [ABSTRACT FROM AUTHOR]

We propose a quantized feedback-based differential signaling scheme for $2 \times 1$ free space optical (FSO) multiple-input single-output communication systems. The analytical bit error rate (BER) for the proposed differential signaling scheme is derived and compared with the existing differential signaling scheme for FSO systems. The asymptotic BER of the proposed scheme is also determined and it is shown by using the asymptotic BER expression that the proposed scheme achieves full spatial diversity of two. Moreover, the effect of the feedback error on the performance of the proposed scheme is studied and it is demonstrated by simulation-based and analytical results that the proposed scheme significantly outperforms a previously proposed differential signaling scheme in terms of turbulence fades reduction for tolerable feedback errors. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the performance of an asymmetric radio frequency/free space optical (RF/FSO) hybrid satellite-terrestrial cooperative system with two relays utilizing a non-linear decoder (NLD) and a low-complexity piecewise linear (PL) decoder. The satellite transmits data over the RF links to the relays on the ground and the relays follow the decode-and-forward (DF) protocol and transmit the decoded data to a distant destination over FSO links assuming the constant transmit power constraint. The RF and FSO channels of the asymmetric system are assumed to follow the Shadowed-Rician and Gamma-Gamma distributions, respectively. The relays are assumed to have hybrid RF/FSO capabilities and utilize subcarrier intensity modulation scheme for transmitting the decoded signal to the destination. A NLD is derived at the destination of considered system for M-ary phase-shift keying and utilizing the derived NLD, we obtain the error rate and its upper bound. Further, in order to reduce the decoding complexity a PL decoder is derived, which is a sub-optimal decoder and works very close to the NLD. Utilizing the derived PL decoder we obtain a closed form expression of bit error rate for the considered system. Lastly, we show the effect of imperfect channel estimation and optimized power distribution of the relays on the performance of the DF based FSO cooperative system with two relays. [ABSTRACT FROM AUTHOR]

This paper demonstrates a working indoor optical wireless link for smart environment applications. The system utilizes a wide field-of-view (FOV) optical wireless receiver through cleaving the tip of large core plastic optical fibers (POFs) attached to the detector. The quality of the optical link is quantified through bit error rate (BER) measurements. The experimental results show a wide FOV with the uncoded BER in the order of 10-3 for transmission distances up to 35 cm when using two POFs for signal collection. The distance can be improved further by increasing the number of fibers. The transmitted signal format and how the BER measurement is achieved are discussed at length. In addition, details are provided for the design of the electronics to establish the optical wireless link. [ABSTRACT FROM AUTHOR]

A two-way amplify-and-forward (AF) wireless relay network consisting of 2M sources with only a single antenna per source and one relay with multiple N antennas is studied with a self-interference cancelation process at the 2M destinations in this paper. All sources act as both sources and destinations. The closed form of the relay amplifying matrix is optimized under the relay transmit power constraint based on the zero-forcing (ZF) criterion. Additionally, the no-power constraint case of the ZF relaying scheme is investigated, as well. Furthermore, the transmit power consumption at the relay is studied during data transmission. The proposed system performance is evaluated in relation to the average bit error rate (BER) by computer simulation. Finally, numerical results show that the system performance improves as either N or input SNR increases. [ABSTRACT FROM AUTHOR]