Bit Error Probability Research Articles

Adaptive fractional order predictive sliding mode control for congestion control of wireless access networks

AbstractThis article studies congestion control of wireless access networks. In a wireless access network, it is necessary to design a robust active queue management (RAQM) technique to control congestion occurrence and to make the network robust simultaneously against some issues in the wireless link aspects, such as packet error rate (PER) and fading effects. On the other hand, a network is often described by a nonlinear model, in which the delayed packet drop probability is assumed as the input signal. So in this article, a RAQM technique is proposed based on an adaptive fractional order predictive sliding mode control (AFOPSMC) method, through which the following are achieved: (1) the stability of the nonlinear system with input delay is assured, (2) the congestion occurrence is prevented by controlling the queue measurement to the desired value, (3) the robustness against the external disturbances is achieved, and (4) the input signal obtained by the controller is limited between 0 and 1. In contrast to most recently published papers where input delay is ignored in the system description and input saturation is achieved through designing parameters, this article at first proposes a predictor to eliminate the input delay and then designs a compensated system to deal with the input signal constraint. Furthermore, the chattering phenomena, as a commonly caused issue in the sliding mode control, is eliminated based on the adaptive laws designed for the controller parameters. The theoretical results are validated and compared with some other related protocols through numerical simulations using Simulink and professional network simulator 2 (NS2).

Wavelength & mm-Wave Flexible Converged Optical Fronthaul With a Low Noise Si-Based Integrated Dual Laser Source

A widely tunable hybrid InP-Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> dual laser module (DLM) with low linewidth and relative intensity noise (RIN) is used to develop a wavelength and frequency flexible optical fronthaul system for high-capacity wireless networks. The wavelength flexible (over C-band) delivery of 5G signals over an analog radio-over-fiber (A-RoF) system, incorporating wireless transmission at 60 GHz is demonstrated. A phase noise (PN) and frequency offset (FO) cancelling receiver is used to overcome phase/frequency noise from the DLM due to thermal fluctuations, and this reduces the received (error vector magnitude) EVM to as low as 5%. Using the same DLM we demonstrate the mm-wave frequency flexible (over sub-V-band) delivery of 5G and WiGig signals over a simplified converged fronthaul link. The experimental results show excellent performance with bit error ratio (BER) values as low as 8.46×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> and 1.11×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> , and lowest EVMs of 2.4% and 6.1%, achieved for sub-V-band 5G and WiGig signals, respectively. In addition to highlighting the high flexibility of the DLM, this work also presents an approach to deploy this source in future optical-wireless access networks paving way for beyond 5G and 6G technologies.

Anti error and erasure coding for water-to-air visible light communication through wavy water surface with wave height up to 0.6 meters.

Considering large dynamic optical intensity range in a water-to-air (W2A) channel, we propose two promising channel coding schemes, namely the concatenated Reed Solomon-Low Density Parity Check (RS-LDPC) code and Raptor code, for W2A visible light communication (VLC). We establish a W2A-VLC link to verify the performance under different wavy water environments and different water depths with a green light emitting diode (LED). A wave generator is adopted to emulate the wavy water surface with wave height up to 0.6 m. The receiver is fixed 3.2 m above the water, and the transmitter varies from 2.5 m to 4.0 m under the water through a up-down-moveable platform. We test the coding schemes with different code lengths and code rates under 5 MSym/s air-interface symbol rate. Experimental results show that both schemes can reduce the bit error ratio (BER) and frame error rate (FER) of a W2A-VLC system, and thus can improve the reliability. Via comparing the two codes with the same overhead and approximately the same code length, it is demonstrated that Raptor code can generally outperform the concatenated RS-LDPC code. Our research provides promising channel coding methods without feedback for a W2A-VLC system.

Error rates of arbitrary order optical wireless pulse-position modulation: An efficient approach

We present analytical results on the bit-error probability (BEP) of arbitrary order pulse-position modulation (PPM) of optically pre-amplified receivers. We use the Laguerre photon counting distribution so as to model the statistic of the optical noise, in order to accurately model the effects of signal and spontaneous noise beating at the optical detector. The great advantage of our proposed results is that they are exact and only require a finite summation over the optical noise modes and the modulation order. In addition, this approach enables the efficient calculation of the BEP in optical wireless communication links, under the presence of atmospheric scintillations and pointing errors.

Monolithic integrated two-stage cascaded SOA-PIN receiver for high-speed optical wireless communication.

Monolithic integrated receivers are highly desired due to the potential of mass production and the reduction of device size and cost. In this Letter, a monolithic integrated optical wireless communication (OWC) receiver with optical preamplifiers is designed, fabricated, and investigated to achieve high sensitivity based on photonic integration technology. The proposed receiver consists of one waveguide PIN photodetector integrated with two semiconductor optical amplifiers (SOAs). Compared with using a one-stage optical amplifier, using two independent SOAs as a two-stage amplifier offers the advantage of optimizing the noise figure of each amplifier independently by tuning their injection currents, which leads to the reduction of the total noise and an improvement of the receiver sensitivity. The achieved sensitivity for a 10-Gb/s OOK signal with 10-dBm launch power at 1550-nm wavelength by using the designed receiver is up to -27.5 dBm at a bit-error-ratio (BER) level of 3.1×10-3 over a 0.9-m indoor free-space link. The experimental results show the potential to achieve a high-speed OWC link with high sensitivity by using a cascaded SOA/PIN monolithic integrated receiver.

Reconfigurable intelligent surface assisted downlink INOMA system

AbstractNonorthogonal multiple access (NOMA) and reconfigurable intelligent surface (RIS) methods are explored to enhance spectral and energy efficiency of a wireless network. In this article, we have proposed a downlink RIS‐assisted index modulation NOMA for next‐generation wireless systems, and it is referred to as R‐INOMA. In the proposed R‐INOMA system, a base station transmits information through RIS to three users, the first user is assigned in the spatial domain and the remaining two users are multiplexed using power domain NOMA. We provide an analytical analysis of bit error probability (BEP) for the proposed R‐INOMA system. Impact of number of surfaces, transmit antennas, modulation order, diversity order, and imperfect channel estimation is analyzed for the R‐INOMA. Simulation results show that the proposed R‐INOMA achieved better BEP and sum‐rate over existing NOMA techniques. In the R‐INOMA, doubling of the reflecting surfaces provides a 4 dB gain for a fixed error probability, and the sum‐rate improves as the number of transmitting antennas and reflecting surfaces increases.

High linearity silicon DC Kerr modulator enhanced by slow light for 112 Gbit/s PAM4 over 2 km single mode fiber transmission.

We demonstrate a high efficiency, high linearity and high-speed silicon Mach-Zehnder modulator based on the DC Kerr effect enhanced by slow light. The two modulation arms based on 500-µm-long grating waveguides are embedded with PN and PIN junctions, respectively. A comprehensive comparison between the two modulation arms reveals that insertion loss, bandwidth and modulation linearity are improved significantly after employing the DC Kerr effect. The complementary advantages of the slow light and the DC Kerr effect enable a modulation efficiency of 0.85 V·cm, a linearity of 115 dB·Hz2/3, and a bandwidth of 30 GHz when the group index of slow light is set to 10. Furthermore, 112 Gbit/s PAM4 transmission over 2 km standard single mode fiber (SSMF) with bit error ratio (BER) below the soft decision forward error correction (SD-FEC) threshold is also demonstrated.

An improved genetic algorithm approach to spectrum sensing for long range based cognitive radio networks

AbstractBy designing cognitive radio networks (CRNs) for low power wide area networks (LPWANs), adaptive spectrum sensing plays an important role in using frequency bands effectively. With spectrum sensing, existing spectrum holes are filled by enabling secondary users to use the licensed band that primary users do not use. Many researchers have proposed various optimization or artificial intelligence techniques in CRNs for spectrum sensing. However, there is hardly any adaptive spectrum sensing method integrated into the LoRa communication standard, which is a very popular LPWAN technology. For this purpose, an adaptive optimization based spectrum sensing methodology with an improved genetic algorithm is proposed in this study. Depending on this methodology, two fitness functions adapted to the LoRa‐based network are defined. Thanks to these functions, the movement of individuals in the network population is provided. In parallel, received signal strength values of optimum LoRa nodes were determined by genetic coding, and bands to be used by SUs instead of PUs were discovered considering minimum bit errors. To verify the success of the proposed method, various simulation experiments were carried out. The performance results strikingly show that the proposed method is quite successful for LoRa‐CRNs. For example, the proposed method significantly improved the bit error rate performance, and reduced the number of faulty transmissions caused by packet collisions. It also reduced the packet error rate by more than 8% per minute in a 200‐node network.

Convolutional Neural Network-Aided DP-64 QAM Coherent Optical Communication Systems

Optical nonlinearity impairments have been a major obstacle for high-speed, long-haul and large-capacity optical transmission. In this paper, we propose a novel convolutional neural network (CNN)-based perturbative nonlinearity compensation approach in which we reconstruct a feature map with two channels that rely on first-order perturbation theory and build a classifier and a regressor as a nonlinear equalizer. We experimentally demonstrate the CNN equalizer in 375 km 120-Gbit/s dual-polarization 64-quadrature-amplitude modulation (64-QAM) coherent optical communication systems. We studied the influence of the dropout value and nonlinear activation function on the convergence of the CNN equalizer. We measured the bit-error-ratio (BER) performance with different launched optical powers. When the channel size is 11, the optimum BER for the CNN classifier is 0.0012 with 1 dBm, and for the CNN regressor, it is 0.0020 with 0 dBm; the BER can be lower than the 7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> hard decision-forward threshold of 0.0038 from −3 dBm to 3 dBm. When the channel size is 15, the BERs at −4 dBm, 4 dBm and 5 dBm can be lower than 0.0020. The network complexity is also analyzed in this paper. Compared with perturbative nonlinearity compensation using a fully connected neural network (2392-64-64), we can verify that the time complexity is reduced by about 25 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> , while the space complexity is reduced by about 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> .

Efficient Message Passing Receivers for Downlink MIMO-SCMA Systems

Sparse code multiple access (SCMA) and multiple input multiple output (MIMO) are considered as two efficient techniques to provide both massive connectivity and high spectrum efficiency for future machine-type wireless networks. However, the computational complexity of the conventional message passing algorithm (MPA) for the downlink MIMO-SCMA detection increases exponentially with the degree of variable nodes (VNs). To address this issue, two novel fixed low complexity MPA detectors are proposed by utilizing the sparse feature of codewords, which are based on the serial schedule strategy in order to accelerate their convergence. First, a maximum distance MPA (MDMPA) detector is introduced to reduce the number of VNs involved in the message updating procedure in the first <inline-formula><tex-math notation="LaTeX">$T_0$</tex-math></inline-formula> iterations and fix <inline-formula><tex-math notation="LaTeX">$TJ_0$</tex-math></inline-formula> codewords at the <inline-formula><tex-math notation="LaTeX">$L_0$</tex-math></inline-formula> iteration, which subsequently drops the redundant codeword combinations in the remaining iterations. To further improve the bit error ratio (BER) performance, an improved MDMPA (IMDMPA) is proposed, in which, the VNs associated with the target user are always allowed to participate in the iterative propagation of message. An efficient linear squares (LS) channel estimation scheme is also derived based on block pilots by stacking all the received signals at the same subcarrier together. Simulation results illustrate that the proposed MDMPA and IMDMPA detectors significantly reduce the computational complexity of the original MPA, but with comparable decoding capabilities, and the proposed LS channel estimator can closely approach the corresponding lower bound over frequency selective channels.

Unity-Rate Coding Improves the Iterative Detection Convergence of Autoencoder-Aided Communication Systems

A forward error correction (FEC) and unity-rate coded (URC) autoencoder (AE)-assisted communication system is proposed for the first time, which relies on soft iterative decoding for attaining a vanishingly low error probability. The AE-demapper is specifically designed for directly calculating the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">extrinsic</i> logarithmic likelihood ratios (LLRs), which can be directly entered into the URC decoder for soft iterative decoding. This avoids the potential degradation due to the conversion of symbol probabilities to bit LLRs. A comprehensive capacity analysis of the AE is performed, which demonstrates the capacity advantage of the AE-aided constellation design over its conventional quadrature amplitude modulation (QAM)/ phase shift keying (PSK) counterpart. Furthermore, we carry out its EXtrinsic Information Transfer (EXIT) chart analysis, which indicates that as a benefit of our URC, the EXIT curve always reaches the [1,1] point of perfect convergence, leading to a vanishingly low error probability. More explicitly, our bit error ratio (BER) and block error ratio (BLER) results demonstrate that the proposed FEC-URC-AE system achieves significant iterative gains both in additive white Gaussian noise (AWGN) and Rayleigh channels, outperforming both its model-based FEC-AE and its conventional coded QAM/QPSK counterparts.

Evaluation of Receiver-Feedback Techniques for Fragmentation Over LPWANs

The Internet engineering task force (IETF) has standardized a new framework for IPv6 support over low-power wide-area networks (LPWANs), called static context header compression and fragmentation (SCHC). SCHC includes acknowledgment (ACK)-based mechanisms for reliable fragmented packet transmission. For the latter, SCHC defines a receiver-feedback technique (RFT), called compressed bitmap (CB), by which a receiver reports to the sender whether the fragments carrying a packet have been received or not. Such information is carried as ACK payload. Considering the extraordinary frame size and message rate constraints of LPWANs, ACK payload size becomes crucial. In this article, we compare the performance of CB with that of several alternative RFTs, namely, list of lost fragments (LLF), List of Deltas (LoD), and uncompressed bitmap (UB), where the latter is used as a benchmark. We evaluate the considered RFTs in terms of ACK size, number of Layer 2 (L2) frames needed to carry an ACK, and ACK Time on Air. Our analysis shows that the use of RFTs different from CB offers significant performance improvement in many scenarios. Furthermore, we provide guidance on which RFT should be used for different packet sizes, error rates, and error patterns.

Performance Analysis of an Adaptive Rate Scheme for QoE-Assured Mobile VR Video Streaming

The emerging 5G mobile networks are essential enablers for mobile virtual reality (VR) video streaming applications assuring high quality of experience (QoE) at the end-user. In addition, mobile edge computing brings computational resources closer to the user equipment (UE), which allows offloading computationally intensive processing. In this paper, we consider a network architecture for mobile VR video streaming applications consisting of a server that holds the VR video content, a mobile edge virtualization with prefetching (MVP) unit that handles the VR video packets, and a head-mounted display along with a buffer, which together serve as the UE. Several modulation and coding schemes with different rates are provided by the MVP unit to adaptively cope with the varying wireless link conditions to the UE and the state of the UE buffer. The UE buffer caches VR video packets as needed to compensate for the adaptive rates. A performance analysis is conducted in terms of blocking probability, throughput, queueing delay, and average packet error rate. To capture the effect of fading severity, the analytical expressions for these performance metrics are derived for Nakagami-m fading on the wireless link from the MVP unit to the UE. Numerical results show that the proposed system meets the network requirements needed to assure the QoE levels of different mobile VR video streaming applications.

Mitigation of scintillation in FSO communication using a temporally and spatially incoherent spectrum-sliced light source.

We propose and demonstrate a temporally and spatially incoherent spectrum-sliced light source for scintillation mitigation in free-space optical (FSO) communications. For the temporal incoherence, we utilize the spectrum-sliced incoherent light (SSIL) modulated by gain-saturated reflective semiconductor optical amplifiers for data modulation and the suppression of excess intensity noise inherent in a narrowband incoherent light source. We then employ offset launching from a single-mode fiber to a multi-mode fiber to add the spatial incoherence to the SSIL source. The experimental demonstration shows that this temporally and spatially incoherent light is effective in mitigating scintillation. For example, this light source reduces the transmitter power required to achieve a bit-error ratio of 10-3 by ∼6 dB in comparison with the laser source. This is an ∼3 dB larger reduction in the transmitter power than the reduction achieved by a temporally incoherent light source.

Total Internal Reflection Lens for Optical Wireless Receivers

This work considers the use of a freeform total internal reflection (TIR) lens for optical concentration and provides for the first time experimental results in the context of optical wireless communications (OWC). The lens is placed on a surface-mounted device (SMD) avalanche photodiode (APD) to minimize position tolerances and simplify assembly. The lens achieves a concentration ratio of go = 44.7 (16.5 dB) within the FOV center and exhibits an acceptance angle of ±5°. The TIR lens approach is validated by comparing eye diagrams and bit error ratios (BER) of a receiver with and without a TIR lens. For the measurements, non-return-to-zero (NRZ) on-off keying (OOK) signals are transmitted with a data rate of 1.289 Gbit/s.

Performance investigation of the probability-aided maximum likelihood sequence detector for a probabilistic shaped 16-QAM system.

In this paper, for the first time, a probability-aided maximum-likelihood sequence detector (PMLSD) is experimentally investigated through a 64-GBaud probabilistic shaped 16-ary quadrature amplitude modulation (PS-16QAM) transmission experiment. In order to relax the impacts of PS technology on the decision module, a PMLSD decision scheme is investigated by modifying the decision criterion of maximum-likelihood sequence detector (MLSD) correctly. Meanwhile, a symbol-wise probability-aided maximum a posteriori probability (PMAP) scheme is also demonstrated for comparison. The results show that the PMLSD scheme outperforms the direct decision scheme about 1.0-dB optical signal to noise ratio (OSNR) sensitivity. Compared with symbol-wise PMAP scheme, PMLSD scheme can effectively relax the impacts of PS technology on the decision module and a more than 0.8-dB improvement in terms of OSNR sensitivity in back-to-back (B2B) case is obtained. Finally, we successfully transmit the PS-16QAM signals over a 2400-km fiber link with a bit error ratio (BER) lower than 1.00×10-3 by adopting the PMLSD scheme.

Multiple-Aperture Direct-Detection Receiver Based on Maximal Ratio Combining for FSO Communication

Collecting light using multiple small apertures offers a lot of advantages over doing so using a single large aperture, including the effective mitigation of scintillation under strong turbulence, low implementation cost, and ease of scalability. In this work, we experimentally demonstrate a free-space optical communication system utilizing a 7-aperture direct-detection receiver based on the maximal ratio combining (MRC) scheme. For the implementation of MRC scheme blindly by using AC-coupled photo-receivers, we estimate the instantaneous signal-to-noise ratio (SNR) from the received signals time-averaged optimally for bit-error ratio performance. The experiment results show that the proposed blind scheme estimates the SNR accurately, and thus performs similarly to the pilot-symbol-aided scheme.

Genetic algorithm-based hybrid spectrum handoff strategy in cognitive radio-based internet of things

In Cognitive radio-based Internet of Things (CR-IoT) systems, the return of the primary user (PU) causes the secondary user (SU) that is communicating to face the spectrum handoff problem. In the process of spectrum handoff, the user terminal cant get the idle channels in time because of the unknown channel usage state.To solve this problem, a hybrid spectrum handoff algorithm based on genetic algorithm is proposed. The algorithm considers the regularity of PU activities in space and time, defines the idle probability of channels from the perspective of week attributes and time periods, obtains the optimal time period length using genetic algorithm,generates a channel idle probability table, and provides the target channel sequence for SUs in combination with the proposed channel ordering scheme. Simulation results show that when the total number of SUs is within 10 \(\sim \) 20, the proposed algorithm has a spectrum handoff outage probability of less than 7%, an average delivery time of less than 13s, a total packet error rate of less than 5.5%, a channel utilization of consistently above 70%, and an average detection times of less than 7 times.

Secrecy Enhancement for SSK-Based Visible Light Communication Systems

Visible light communication (VLC) is a technology that uses unlicensed light spectrum resources and high spatial reuse rates for communication. Because it does not occupy any resource allocation in wireless communication, it has fully alleviated the problem of spectrum scarcity in radio frequency (RF) communication and gradually become a new development direction. However, owing to the inherent broadcasting nature of the VLC channel, the VLC link is vulnerable to eavesdropping by unexpected or unauthorized users in spacious public places. Therefore, enhancing the security of the VLC system has attracted extensive attention. This paper studies the security optimization scheme of the VLC system based on the space shift keying (SSK) technology in the free space optical environment called the SSK-VLC system. The antenna selection (AS) technology and artificial noise (AN) cancellation method are adopted to enhance the confidentiality of the SSK-VLC system. In this paper, we presume that the SSK-VLC system includes three parts: a transmitter containing multiple light-emitting diodes, a legitimate receiver, and an eavesdropper, respectively. By using the designed AS and AN method, the transmitted valid information can be demodulated at the legitimate receiver, and at the same time, the received information by the eavesdropper will be disturbed. The simulation results prove that the proposed optimization scheme can further improve the security performance, including the secrecy rate (SR) and the bit error ratio (BER), compared with the traditional SSK-VLC scheme.

Adaptive feedback threshold based demodulation for mobile visible light communication and positioning integrated system.

In this paper, a novel adaptive feedback threshold (AFT) based demodulation for mobile visible light communication and positioning (VLCP) integrated system is proposed. The AFT can vary with the received signal without excessive fluctuation and support communication and positioning in mobile environment. For the VLCP integrated system with single light emitting diodes (LED) and multiple photodetectors (PDs), maximal ratio combining (MRC) and received optical power ratio (ROPR) based on the AFT is further achieved for communication and positioning with high performance, respectively. It is demonstrated that high credible communication and high accuracy positioning for the mobile integrated VLCP system can be realized by using the proposed AFT based demodulation. As a result, the implemented VLCP system with a moving speed of 1 m/s is evaluated experimentally. Average positioning error of 3.43 cm with 800 mA current and the bit error ratio (BER) with different currents are also obtained.