The Optimal Carrier-Secret Ratio for Wireless Covert Channels Based on Constellation Shaping Modulation

Wireless covert communication is an emerging communication technique that prevents eavesdropping. This paper considers the bit error ratio (BER) problem of covert communication based on constellation shaping modulation (CSM). The impact of carrier-secret ratio (CSR) on BER is studied and the approximate solution of optimal CSR is obtained. Then, we extended the conclusion to typical communication scenarios with one and more relays where the undetectability and reliability were analyzed and inspected. It is proved that there also exists the optimal CSR in scenarios with relays. Additionally, it is found that the undetectability under the constraints of constant total power depends on the eavesdropper’s position, and we found an undetectability deterioration area (UDA) in the scenario of relays. Simulation results show the existence of optimal CSR and its impact on transmission performance.

Turbo-coded Ultra Long Haul System with Probabilistic Shaped 16QAM Modulation

With the rapid growth and development of 5G (5th Generation Mobile Communication Technology) and the incoming of 6G (6th Generation Mobile Communication Technology), the demand for high-speed and flexible communication solutions is becoming far more urgent. Within this paper, a novel code modulation scheme based on PS (probabilistic shaping) and Turbo code is proposed with its effectiveness is confirmed by the results of simulation. The results inform that in an optical fiber communication system with 56 Gb/s rate and 3000 km transmission distance, when the SNR (signal-noise ratio) is greater than 3.5 dB, the Turbo-coded PS-16QAM modulation format can achieve reliable transmission. The proposed scheme performs the best in BER (bit error ratio) and average launch power in the four cases of uniform 16QAM, PS-16QAM, Turbo-coded 16QAM with and itself. The proposed scheme is a potential solution in the future 5G communication.

Dual-carrier modulation (DCM) is used to implement a species of tone reservation to reduce the PAPR of COFDM, wherein the reserved tones convey coded digital data (CDD) a second time. The same CDD is conveyed by carriers in a lower-frequency sub-band of the COFDM and by carriers in a higher- frequency sub-band. Each pair of carriers conveying the same CDD are separated by a subband width, enabling receivers better to ameliorate the effects of multipath reception. There is labeling diversity between the QAM symbol constellations that respectively govern modulation of carriers in the lower- frequency sub-band and modulation of carriers in the higher-frequency subband, which labeling diversity is designed to reduce PAPR of the COFDM. The labeling diversity also improves bit-error ratio (BER) for increased-size QAM symbol constellations used to increase CDD throughput despite the halving of CDD throughput owing to the use of DCM.

Dual-carrier modulation (DCM) is used to implement a species of tone reservation to reduce the PAPR of COFDM, wherein the reserved tones convey coded digital data (CDD) a second time. The same CDD is conveyed by carriers in a lower-frequency sub-band of the COFDM and by carriers in a higher- frequency sub-band. Each pair of carriers conveying the same CDD are separated by a subband width, enabling receivers better to ameliorate the effects of multipath reception. There is labeling diversity between the QAM symbol constellations that respectively govern modulation of carriers in the lower- frequency sub-band and modulation of carriers in the higher-frequency subband, which labeling diversity is designed to reduce PAPR of the COFDM. The labeling diversity also improves bit-error ratio (BER) for increased-size QAM symbol constellations used to increase CDD throughput despite the halving of CDD throughput owing to the use of DCM.

Efficient Non-Uniform Pilot Design for TDCS

The Internet of Things (IoT) leads the era of interconnection, where numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, wireless communication technologies have to overcome available spectrum shortage and complex fading channels. The transform domain communication system (TDCS) is a cognitive anti-interference communication system with a low probability of detection and dynamic spectrum sensing and accessing. However, the non-continuous and asymmetric spectrum brings new challenges to the traditional TDCS block-type pilot, which uses a series of discrete symbols in the time domain as pilots. Low efficiency and poor adaptability in fast-varying channels are the main drawbacks for the block-type pilot in TDCS. In this study, a frequency domain non-uniform pilot design method was proposed with intersecting, skewing, and edging of three typical non-uniform pilots. Some numerical examples are also presented with multipath model COST207RAx4 to verify the proposed methods in the bit error ratio and the mean square error. Compared with traditional block-type pilot, the proposed method can adapt to the fast-varying channels, as well as the non-continuous and asymmetric spectrum conditions with much higher efficiency.

Improvement of Multipath Channel Performance for Optical MIMO-OFDM in LED Modulation with Fully Generalized Spatial-Frequency

This paper suggests a scheme to generalize the idea of LED index modulation concept by using the spatial multiplexing principle to relay complex OFDM signals through various channels such as AWGN, Rayleigh and Rician by splitting these signals into their real-imaginary and positive-negative components. In order to combat ISI as well as to increase the channel capacity. The MIMO-OFDM efficiency analysis, taking into account the constraint of the forward current of the LED is extracted. The accuracy of the theoretical results is verified by comparing the Bit Error Ratio (BER) reduction and improvement to the (SNR) results under varying condition of the channel. Using MIMO-OFDM as next-generation techniques, along with QAM aims to provide development of new concepts that will lead to the growth of future optical communication. Simulation results validate data rates gained over optical communication using LED modulation scheme and the pure transmission diversity method.

Performance Analysis of Sphere Packed Aided Differential Space-Time Spreading with Iterative Source-Channel Detection

The introduction of 5G with excessively high speeds and ever-advancing cellular device capabilities has increased the demand for high data rate wireless multimedia communication. Data compression, transmission robustness and error resilience are introduced to meet the increased demands of high data rates of today. An innovative approach is to come up with a unique setup of source bit codes (SBCs) that ensure the convergence and joint source-channel coding (JSCC) correspondingly results in lower bit error ratio (BER). The soft-bit assisted source and channel codes are optimized jointly for optimum convergence. Source bit codes assisted by iterative detection are used with a rate-1 precoder for performance evaluation of the above mentioned scheme of transmitting sata-partitioned (DP) H.264/AVC frames from source through a narrowband correlated Rayleigh fading channel. A novel approach of using sphere packing (SP) modulation aided differential space time spreading (DSTS) in combination with SBC is designed for the video transmission to cope with channel fading. Furthermore, the effects of SBC with different hamming distances d(H,min) but similar coding rates is explored on objective video quality such as peak signal to noise ratio (PSNR) and also the overall bit error ratio (BER). EXtrinsic Information Transfer Charts (EXIT) are used for analysis of the convergence behavior of SBC and its iterative scheme. Specifically, the experiments exhibit that the proposed scheme of error protection of SBC d(H,min) = 6 outperforms the SBCs having same code rate, but with d(H,min) = 3 by 3 dB with PSNR degradation of 1 dB. Furthermore, simulation results show that a gain of 27 dB Eb/N0 is achieved with SBC having code rate 1/3 compared to the benchmark Rate-1 SBC codes.

Mitigation of Nonlinear Phase Noise in Single-channel Coherent 16-QAM Systems Employing Logistic Regression

We propose and analyze a classier based on logistic regression (LR) to mitigate the impact of nonlinear phase noise (NPN) caused by Kerr induced self-phase-modulation in digital coherent systems with single-channel unrepeated links. Simulation results reveal that the proposed approach reduces the bit error ratio (BER) in a 100-km-long 16 quadrature amplitude modulation (16-QAM) system operating at 56-Gbps. Thus, the BER is reduced from 6.88·10 -4 when using maximum likelihood to 4.27·10 -4 after applying the LR-based classification, representing an increase of 0.36 dB in the effective Q-factor. This performance enhancement is achieved with only 624 operations per symbol, which can be easily parallelized into 16 lines of 39 operations.

Evaluation of Misalignment Effect in Vehicle-to-Vehicle Visible Light Communications: Experimental Demonstration of a 75 Meters Link

The use of visible light communications technology in communication-based vehicle applications is gaining more and more interest as the research community is constantly overcoming challenge after challenge. In this context, this article addresses the issues associated with the use of Visible Light Communications (VLC) technology in Vehicle-to-Vehicle (V2V) communications, while focusing on two crucial issues. On the one hand, it aims to investigate the achievable communication distance in V2V applications while addressing the least favorable case, namely the one when a standard vehicle rear lighting system is used as a VLC emitter. On the other hand, this article investigates another highly unfavorable use case scenario, i.e., the case when two vehicles are located on adjacent lanes, rather than on the same lane. In order to evaluate the compatibility of the VLC technology with the usage in inter-vehicle communication, a VLC prototype is intensively evaluated in outdoor conditions. The experimental results show a record V2V VLC distance of 75 m, while providing a Bit Error Ratio (BER) of 10−7–10−6. The results also show that the VLC technology is able to provide V2V connectivity even in a situation where the vehicles are located on adjacent lanes, without a major impact on the link performances. Nevertheless, this situation generates an initial no-coverage zone, which is determined by the VLC receiver reception angle, whereas in some cases, vehicle misalignment can generate a BER increase that can go up to two orders of magnitude.

Eigenvalue Decomposition Precoded Faster-Than-Nyquist Transmission of Index Modulated Symbols

Postprint accepted on 30 April 2021 for publication in IEEE International Symposium on Information Theory (ISIT), 2021. (c) 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.<div>In this paper, we propose a precoded faster-than-Nyquist (FTN) signaling technique for time-domain single-carrier index modulated (IM) symbol transmission. More precisely, eigenvalue decomposition precoding is adopted for the FTN transmission of data bits modulated by single-carrier time-domain IM. While the FTN scheme increases the spectral efficiency and data rate by packing more transmit symbols per block duration than those defined in the Nyquist criterion, time-domain IM works towards the same objective while maintaining symbol sparsity. We analytically derive the constrained capacity of the proposed system. Our simulation results show that the proposed scheme has better bit error ratio (BER) performance over the conventional FTN-IM scheme, particularly for the scenario of a higher packing ratio. In the proposed scheme, $2.5$-dB performance gain is observed at the BER of 10^-4, employing the packing ratio of $0.7$ and the roll-off factor of $0.5$ in a channel-uncoded scenario.<br></div>