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The mixture of wireless and power line communications (PLC) is vital for implementing new applications in smart grid and vehicular communications. In this work, we investigate the performance of non-orthogonal multiple access (NOMA) based dual-hop hybrid communication systems with decode-and-forward relay. The wireless channel is characterized by Nakagami-m fading under an additive white Gaussian noise (AWGN), while the PLC channels are characterized by Log-normal distribution with Bernoulli Gaussian noise including both background and impulsive noise components. New closed-form expressions for the outage probability, the asymptotic outage probability and ergodic capacity are derived and verified via extensive representative simulations. For more insights on the outage performance, we analyze the diversity order. Additionally, we proposed a power allocation optimization technique to achieve an outage-optimal performance. The results show that the system outage probability improves as the impulsive noise index and the arrival probability of the impulsive component of the PLC additive noise decrease, while their effect is negligible on the ergodic capacity. Finally, the performance of the proposed system is compared against a benchmark OMA-based system. [ABSTRACT FROM AUTHOR]

The performance of belief propagation list (BPL) decoding of polar codes is related to the selection of $L$ factor graphs (FGs), which have the least number of girths. However, the straightforward search of such FGs is of high complexity. To achieve good performance with reasonable complexity, we propose an efficient method to find FGs with the least number of length-12 loops in all permuted FGs. Since some length-12 loops have been destroyed by redundant decoding operations, the corresponding FGs can be simplified to different numbers of length-12 loops. Thanks to the proposed loop simplification (LS), BPL decoding is now based on more efficient FGs, resulting in better performance and lower average decoding latency than the state-of-the-art. Numerical results have shown that the performance improvement is 0.15 dB when frame error ratio (FER) is $10^{-4}$ , for $(1024, 512)$ codes with $L=64$. [ABSTRACT FROM AUTHOR]

Vehicular power line communication (VPLC) is being considered as a potential solution to mitigate the increase of complexity and cost of the automotive wiring harness caused by the growth of the number of electronic devices and sensors deployed inside vehicles. This is because VPLC reuses power cables for data communication and, thus, avoids the need for additional communication wires. However, this reuse does not come without problems. One of the challenges for VPLC is the time, frequency, and location dependence of the access impedance, which can cause severe impedance mismatch for the communication signal. Impedance mismatch degrades the signal-to-noise-power ratio at the communication receiver and thus affects transmission reliability. Due to the variable nature of the access impedance, a fixed matching circuit will be inefficient. Hence, in this work, we present an adaptive impedance-matching system, which improves the communication-signal transfer from the transmitting to the receiving device. The system is evaluated via simulations for a wide range of access-impedance test points and $S$- parameters of VPLC networks obtained in previous measurement campaigns. Our simulation results demonstrate that the presented adaptive matching system is able to achieve VPLC signal-power transfer within 30% of the theoretical optimum. This translates to a power gain, up to a factor of 10, which is larger than that of other solutions reported in the literature. [ABSTRACT FROM PUBLISHER]

In-vehicle communications are emerging to play an important role in the continued development of reliable and efficient X-by-Wire applications in new vehicles. Since vehicle devices, sensors, and the electronic control unit (ECU) are already connected to power wires, the advancement of power line communications (PLCs) can provide a very low cost and virtually free platform for in-vehicle communications. In this paper, we propose a medium access control (MAC) protocol for vehicular PLC systems, where multiple nodes are competing for transmission over the direct current (dc) power line. The proposed protocol uses a combination of time and frequency multiplexing and consists of two key features: 1) a distributed channel selection policy to arbitrate packet transmission across different channels and provide robustness against interference and noise and 2) a distributed collision resolution algorithm to allow efficient nodes completion over selected channels. Specifically, the collision resolution algorithm is optimized with respect to the channel policy such that the success probability of transmission in each channel is maximized. Numerical results are also supplemented to validate the performance of the proposed protocol and provide useful guidelines for developing a robust contention-based MAC protocol for vehicular PLC systems. [ABSTRACT FROM PUBLISHER]