Construction and Performance of Quantum Burst Error Correction Codes for Correlated Errors

This paper investigates the decoding performance of channel-coded ship-based satellite communications on-the-move (SSCOTM) between ships and satellites. In practical communications, ship antennas deviated from satellites by wind waves suffer rapid channel degradation with serious burst errors and even losing all the data. To address this issue, we first establish a mathematical model to study the influence of wind waves and derive the effective signal-to-noise ratio (SNR) in SSCOTM. Second, we propose a vertical Reed-Solomon (RS) with cyclic redundancy check (CRC) and low-density parity check (VRC-LDPC) code, where the RS code and LDPC code are treated as the inner code and outer code to correct both burst and random errors, respectively. Moreover, both the encoder and the decoder of the proposed VRC-LDPC can be carried out in parallel implementations. Finally, simulation results show that the proposed VRC-LDPC performs much better than the conventional codes of the Consultative Committee for Space Data Systems (CCSDS) standard. Thus, this paper provides an excellent alternative channel code for reliable error-correction systems of SSCOTM.

Ensuring confidentiality of communication is fundamental to securing the operation of a wireless system, where eavesdropping is easily facilitated by the broadcast nature of the wireless medium. By applying distributed beamforming among a coalition, we show that a new approach for assuring physical layer secrecy, without requiring any knowledge about the eavesdropper or injecting any additional cover noise, is possible if the transmitters frequently perturb their phases around the proper alignment phase while transmitting messages. This approach is readily applied to amplitude-based modulation schemes, such as PAM or QAM. We present our secrecy mechanisms, prove several important secrecy properties, and develop a practical secret communication system design. We further implement and deploy a prototype that consists of 16 distributed transmitters using USRP N210s in a 20×20×3m3 area. By sending more than 160M bits over our system to the receiver, depending on system parameter settings, we measure that the eavesdroppers failed to decode 30%–60% of the bits cross multiple locations while the intended receiver has an estimated bit error ratio of 3×10−6.

Most practical communication systems need higher bandwidth efficiency; this article increased the bandwidth efficiency through code rate and modulation mode, by combining Non-binary LDPC code with MSK modulation and making practical use of them in communication systems. The simulation result showed that the combination of Non-binary LDPC code and MSK modulation possessed not only a stronger error correcting capability but also a higher bandwidth efficiency, which will probably be more applicable in practical communication systems.

With the popularization of Internet-of-things (IoT) and wireless communication systems, a diverse set of applications in smart cities are emerging to improve the city-life. These applications usually require a large coverage area and minimal operation and maintenance cost. To this end, the recently emerging backscatter communication (BC) is gaining interest in both industry and academia as a new communication paradigm that provides high energy efficient communications that may even work in a battery-less mode and, thus, it is well suited for smart city applications. However, the coverage of BC in urban area deployments is not available, and the feasibility of its utilization for smart city applications is not known. In this article, we present a comprehensive coverage study of a practical cellular carrier-based BC system for indoor and outdoor scenarios in a downtown area of a Helsinki city. In particular, we evaluate the coverage outage performance of different low-power and wide area technologies, i.e., long range (LoRa) backscatter, arrow band-Internet of Things (NB-IoT), and Bluetooth low energy (BLE) based BC at different frequencies of operation. To do so, we carry out a comprehensive campaign of simulations while using a sophisticated three-dimensional (3D) ray tracing (RT) tool, ITU outdoor model, and 3rd generation partnership project (3GPP) indoor hotspot model. This study also covers the energy harvesting aspects of backscatter device, and it highlights the importance of future backscatter devices with high energy harvesting efficiency. The simulation results and discussion provided in this article will be helpful in understanding the coverage aspects of practical backscatter communication system in a smart city environment.

For applying to various error patterns, including random errors, burst errors, and inhomogeneously distributed errors, in the holographic data storage (HDS) channel, a three-dimensional error correcting with matched interleaving (3DEC-MI) scheme is proposed in this paper. The 3DEC-MI scheme combines the advantages of the three-dimensional error correcting scheme and the matched interleaving scheme, makes full use of the priori knowledge of the error patterns in the HDS channel, distributes errors more uniformly, and decodes data iteratively in three dimensions. It is able to eliminate the influences of non-uniform distribution of errors within a page and across pages, overcome the effects of burst errors, correct random errors, and effectively reduce the symbol error rate (SER) of the HDS channel.

In this paper, we analyze the physical layer secrecy performance of two-bit feedback based 4 × 1 multiple-inputsingle-output communication system in the presence of a single antenna equipped passive eavesdropper over Rayleigh faded channel. To achieve full-rate and spatial diversity real orthogonal space-time block code is employed in the considered wiretap communication system. In a practical wireless communication system, it is not always possible to acquire full channel knowledge. Thereby, in this paper, we exploit the partial channel state information at the transmitter with the help of two-bit quantized feedback based diagonal precoder. Further, exact closed-form expressions of the secrecy outage probabilities are derived over perfect and imperfect feedback bits by using order statistics. It is shown in the numerical results that an optimized power allocation scheme successfully improves secrecy performance gain under erroneous feedback in comparison to other schemes.

Study on the regulation of amplitude for the optical soliton through nonlinear effects in the optical communication system

In this paper, based on the phase-position perturbation method, an innovative optimal adaptive antenna technique is proposed, where the deduced radiation pattern formulas available for searching optimal solutions are used to search the optimal weighting vector. The optimal radiation pattern designs of adaptive antenna are studied by the phase-position perturbation method. Memetic algorithms are used to search the optimal weighting vector of the phase-position perturbations for the array factor. The design for an optimal radiation pattern of an adaptive antenna can not only adjustably suppress the interferers by placing nulls at the directions of the interfering sources, but at the same time provide a maximum main lobe in the direction of the desired signal, i.e., to maximize the signal-to-interference ratio. To achieve this goal, a new convergent method, referred to as the two-way convergent method for memetic algorithms, is proposed. The memetic algorithm combines a genetic algorithm and local search heuristics to solve combinatorial optimization problems. The memetic algorithm is a kind of improved type of the traditional genetic algorithm. By using a local search procedure, it can avoid the shortcomings of the traditional genetic algorithm, whose termination criteria are set up by using the trial and error method. This proposed method is also able to solve the multipath problem, which exists at the same time in this communication system. The optimal radiation pattern concept can be implemented in practical wireless communication systems. Simulation results are also given in this paper.

In this paper, we propose a practical system for private communications with chaos using digital signal processor (DSP). Recently, many analog circuits for private communications with chaos have been proposed. The core technique of this method is based on the strict parameter matching between the transmitter and the receiver system. However, it seems difficult, at least practically in analog circuits, to match the transmitter parameters with the receiver parameters for a long time. Therefore, we try to use the DSP for modulation and demodulation systems by assuming the digital transmission line such as computer networks. Today the DSP has calculation performance over 10 MIPS, therefore, almost all the calculation processes for modulation and demodulation can be performed in real time in audio frequency range. We investigate the round-off error problem peculiar to the fixed point DSP with finite bit length variables, and then propose a new algorithm that can overcome this problem to achieve perfect information recovery characteristics using the 16-bits fixed point DSP.

The high-conductivity conditions underwater create considerable difficulties for current high-frequency communication systems. Very Low Frequency (VLF) communication has become a viable solution due to its reduced radiation attenuation. However, traditional long-wave antennas require large sizes to operate at these frequencies, which makes them difficult to transport, install, and maintain. Mechanical antennas, on the other hand, generate electromagnetic radiation by using mechanical vibrations to induce the flipping of electric or magnetic dipoles within the material, overcoming the size and efficiency limitations of conventional long-wave antennas and enabling miniaturization. Current research on mechanical antennas primarily focuses on signal transmission in single media, such as air or water, while studies on cross-medium communication systems remain underdeveloped. In this study, a mechanical antenna made from magnetoelectric (ME) composite materials was used to investigate cross-medium communication performance in a practical communication system. The basic theory of mechanical antennas was first explained. An antenna suitable for the desired frequency was designed through simulation, verifying its equivalence to a magnetic dipole model. Based on electromagnetic wave transmission theory across air-water media, an electromagnetic field model for vertical magnetic dipole cross-medium transmission was established. Afterward, the mechanical antenna was fabricated. Relevant tests were conducted in an actual communication system. The results showed that the designed Metglas-PZT mechanical antenna, operating a resonant frequency of 14.1 kHz, achieved a communication rate of 200 bps and error-free text transmission over a total distance of 1 meter, including 0.7 meters in air and 0.3 meters underwater, using 2ASK modulation. These results confirm the feasibility of mechanical antennas for air-water cross-medium communication and provide important references for future research in underwater communication.

SummaryThis paper presents an effective scheduling scheme for sphere decoding (SD) with runtime constraints, targeting the practical multiple‐input multiple‐output (MIMO) communication systems where neither the interleaving scheme nor its block size cannot be designed freely. The proposed scheme imposes runtime constraints on SD to distribute the errors due to the early termination of SD. Because the distributed errors may be corrected effectively by forward error correction, the error‐rate performance can be improved; experimental results show that the performance improvement is approximately 2dB in terms of the signal‐to‐noise ratio to achieve a bit‐error rate of 10−4 in 4 × 4 16‐QAM MIMO systems. Copyright © 2015 John Wiley & Sons, Ltd.

Most of the power control (PC) algorithms assumed that the link gains are fixed, and the power control command can take any value in the real field. These two assumptions are unrealistic in actual communication systems, since link gains are time varying and power control commands must be sent over capacity limited channels. In this paper, we propose a binary feedback power control algorithm (BFPC) for time-varying link gain environments. This algorithm can possibly be implemented as a 1-bit increase/decrease power control command, and we construct a connection between the link gains and the step-size of the proposed algorithm. It is shown that the proposed algorithm drives the CIR to an interval in time-varying link gain environments. Simulation results show that the proposed algorithm is more robust against link gains changes as compared to Foschini and Miljanic's distributed algorithm (FMA) and proportional power control algorithm (PropPC), and the proposed algorithm can be adopted in practical mobile communication systems.

Orthogonal frequency division multiplexing with index modulation (OFDM-IM) has been recently proposed to increase the spectral efficiency and improve the error performance of multicarrier communication systems. However, all the OFDM-IM systems assume that the perfect channel state information is available at the receiver. Nevertheless, channel estimation is a challenging problem in practical wireless communication systems for coherent detection at the receiver. In this paper, a novel method based on the pilot symbol-aided channel estimation technique is proposed and evaluated for OFDM-IM systems. Pilot symbols, which are placed equidistantly, allow the regeneration of the response of the channel so that pilot symbol spacing can fulfill the sampling theorem criterion. Our results shows that the low-pass interpolation and SPLINE techniques perform the best among all the channel estimation algorithms in terms of bit error rate and mean square error performance.

The aim of the research described in this paper is to eliminate self-interference during the transmission of simultaneous signals over a common channel. Code-division multiple-access (CDMA) communication systems, also termed spread-spectrum multiple access (SSMA) systems, make use of a transmission bandwidth greatly in excess of the information bandwidth. A synchronous CDMA technique known as Sequence Segment Keying (SSK) that provides zero co-channel interference has been proposed and described by Darnell [1]. Previous work in this area has concentrated on the system aspects of SSK describing the application within the design of a practical radio communication system [2]. This paper provides a comprehensive analysis of this communication scheme by introducing a novel mathematical modet of an SSK system. This has been initially tested by computer simulation and verified for an unlimited number of simultaneous users. The conditions imposed on the pseudorandom (PR) bearer sequences for SSK limit those sequences which can be utilised. The lack of large sequence sets restricts the number of simultaneous users and to overcome this problem the use of independent varying chip periods for each PR bearer sequence is examined. This allows sequences that do notmeet specified period criteria to be adjusted so that they are locked into the required sequence length ratios, thus providing a larger sequence set than was previously possible and hence increasing the flexibility and viability of SSK systems.

Two different semi-analytical methods for error probability estimation in PDM-QPSK optical communication systems are investigated. We consider the accuracy of a stochastic semi-analytical method based on Gaussian noise statistics and a deterministic semi-analytical method where the noise probability density function is estimated analytically against Monte-Carlo simulation. Linear coherent PDM-QPSK systems with distortions induced by filtering only, and nonlinear coherent PDM-QPSK systems with or without inline dispersion compensation are studied. Our results suggest that the stochastic semi-analytical method based on Gaussian noise statistics works very well for practical fiber-optic communication systems.