Mathur, Aashish

In this paper, we investigate the pulse jamming effect in Power Line Communication (PLC) systems employing differential chaos shift keying (DCSK) over Log-normally distributed channel gain. Concurrently, the behavior of PLC channel noise is characterized by the Bernoulli-Gaussian random process. Further, the state of the jammer is modeled using a Bernoulli random variable. Depending upon the state of the jammer, we derive the probability density function (PDF) of the instantaneous signal-to-jamming-plus-noise ratio (SJNR) and the instantaneous signal-to-noise ratio (SNR). Furthermore, the series-based expressions of average bit error rate (ABER) and outage probability (OP) are analytically evaluated. Additionally, the asymptotic behavior of ABER is analyzed in terms of the coding gain and diversity order in the high SNR regime. Based on the ABER and OP analysis of the considered PLC system, some fruitful insights are demonstrated by observing the impact of different system parameters.

Owing to the exponential rise in the demand for high data rate communications, massive connectivity requirements in Internet of Things (IoT) based communication applications, and the spectral congestion issues in the traditional radio frequency (RF) based communications, visible light communications (VLC) have garnered attention of academia and industry due to their wide bandwidth, license free spectrum, energy efficiency, and low implementation cost. However, VLC systems are susceptible to interception due to their broadcast nature. In this paper, we investigate the effect of random pulse jamming attacks in indoor VLC systems assuming on-off keying (OOK). The user is assumed to be randomly located, following a uniform distribution, within a circular plane of maximum radius covered by the light emitting diode (LED) transmitter. We derive the cumulative distribution function (CDF) and probability density function (PDF) of the instantaneous signal-to-jamming-plus-noise ratio (SJNR) and the instantaneous signal-to-noise ratio (SNR), depending upon the state of the jammer. Utilizing the statistical characterization of the SJNR and SNR, we derive closed-form expressions of the average bit error rate (ABER) and lower bound on ergodic capacity (EC) of the considered VLC system. Useful insights into the considered VLC system performance are obtained through the impact of various jammer parameters on the system performance metrics.

There is an increasing need for high data rate and massive connectivity requirements in the Internet of Things (IoT) based communication applications. Therefore, visible light communications (VLC) have become a popular area of research for both academia and industry. This is due to wide bandwidth, license-free spectrum, energy efficiency, and low implementation cost of VLC. In addition, traditional radio frequency (RF) based communications face issues with spectral congestion. In this paper, we develop an experimental setup of VLC based data transmission and reception. We demonstrate text and audio transmission over a single VLC link of upto 2 m using light emitting diode (LED) and collimating lens as the transmitter and receiving lens with a PIN photodetector as receiver. VLC system's link length improved up to 4m with an amplify-and-forward (AF) relay for data transmission and reception. Further, it is presented that with 4 LEDs, the distance for error-free transmission for text data increased from 50 cm to 180 cm. Useful insights into the VLC systems performance are obtained through the experimental measurements of the received power for various link lengths, receiver angular position with respect to the transmitter, and the number of the transmitting white LEDs used.

Reconfigurable intelligent surface (RIS) is an emerging technology that can result in a dynamically controllable radio propagation environment by smartly tuning the signal reflections via a large number of low-cost passive reflecting elements. In this paper, we investigate the effect of RIS-aided jammer on distributed RIS-based dual-hop mixed free-space optical (FSO)-radio frequency (RF) communication systems. The channel distribution of the FSO link is assumed to follow a Gamma-Gamma (GG) distributed atmospheric turbulence (AT) model with pointing errors (PEs). The relay-RIS and RIS-destination links are assumed to follow Rayleigh distributions. The received signal at the destination node is corrupted by a RIS-aided jammer. It is assumed that the jammer-RIS and RIS-destination links follow a Rayleigh distribution. Novel closed-form expressions for the outage probability (OP) and bit error rate (BER) of the considered system are derived considering two types of detection schemes, namely intensity modulation/direct detection (IM/DD) and heterodyne detection (HD). Through numerical results, it is shown that the presence of the RIS-aided jammer severely degrades the performance of distributed RIS-based dual-hop mixed FSO-RF systems. Finally, the improvement in performance of dual-hop mixed FSO-RF systems with the use of distributed RIS is also validated through results.

Free space optical (FSO) communication is a promising candidate for the next generation (5G and beyond) wireless communication systems, due to its merits (i.e. low latency, high data rate, and license-free band, among others). However, atmospheric turbulence (AT) as well as pointing error (PE) are two of the main challenges with FSO communication that affect its performance. Here, the exact closed-form expression of the average secrecy capacity and secrecy outage probability under the composite effect of AT and non-zero boresight PEs is evaluated. For all the regimes of the AT (weak to strong), a generalised Malaga distribution is used to model the channel fading gain of the FSO link. The expressions are generalised and valid for all turbulence, and are applicable for intensity modulation direct detection as well as heterodyne detection techniques.

Nowadays, modern world technologies are rapidly becoming part of the Internet of things (IoT) and 5G networks where the role of power line communication (PLC) technology will be predominant in some of the standard applications of IoT such as smart homes, smart industries, and smart grids by considering its favorable conditions. In this paper, we analyze the physical layer security (PLS) of a low-frequency PLC system in terms of average secrecy capacity (ASC), secure outage probability (SOP), and strictly positive secrecy capacity (SPSC) where the wiretap channel model is employed to measure the degree of data confidentiality between authorized and unauthorized user over low frequency PLC networks. The PLC channel characteristics are characterized by specifically, two different cases, when the main and wiretap channel are independent log- normally distributed and correlated log-normally distributed; concurrently the effect of impulsive noise is modeled by the Bernoulli Gaussian process. Furthermore, the impact of impulsive noise, the distance between the users, path loss factor, and transmitted power is also considered. The validity of the derived analytical results is established through close matching with the Monte Carlo based simulation results.

In this letter, we study the physical layer secrecy performance of the classic Wyner's wiretap model over double Rayleigh fading channels for vehicular communications links. We derive novel and closed-form expressions for the average secrecy capacity (ASC) taking into account the effects of fading, path loss, and eavesdropper location uncertainty. The asymptotic analysis for ASC is also conducted. The derived expressions can be used for secrecy capacity analysis of a number of scenarios including vehicular-to-vehicular (V2V) communications. The obtained results reveal the importance of taking the eavesdropper location uncertainty into consideration while designing V2V communication systems.

In this letter, we study the secrecy performance of the classic Wyner's wiretap model, where the main and eavesdropper channels are modeled by a general and versatile α-η-κ-μ fading model. Novel and exact expressions of the average secrecy capacity and secrecy outage probability have been derived. Previous results on physical layer security can be obtained through our newly derived expressions by specializing the model parameters. More importantly, the derived results are also applicable for the secrecy performance analysis of some field measurements (e.g., in millimeter wave communications), which cannot be analyzed by previous results.

Wireless communications and power line communications (PLC) are essential components for smart grid communications. This paper analyses the performance of a dual-hop wireless-power line mixed communication setup employing a decode-and-forward relay in terms of analytical average bit error rate (BER), outage probability, and average channel capacity. The Nakagami- m distribution captures the wireless channel fading; whereas the PLC channel gain is characterized by the Log-normal distribution. The additive PLC channel noise is assumed to be Bernoulli-Gaussian distributed. Approximate closed-form expression of the average BER and exact closed-form expression of the outage probability are derived for the considered system. Further, we obtain an approximate closed-form expression of the capacity of the wireless-power line mixed system in terms of the Meijer-G function. It is observed that the system performance deteriorates as the impulsive noise index and the arrival probability of the impulsive component of the PLC additive noise increase.

This paper presents experimental results for a free-space optical-fiber converged (FSO-FC) communication system under varying turbulence and foggy conditions. Based on the experimental measurements, we statistically characterize the FSO channel under different levels of turbulence and fog in terms of their respective probability density functions (PDFs). Our experimental PDFs fit well with the theoretical PDFs proposed in the literature. We experimentally evaluate the average bit error rate (ABER) of the considered FSO-FC communication system under different levels of turbulence and fog. Further, to compensate for the effects of turbulence and fog, we use multimode fiber as the receiver and compare the results with single-mode fiber as the receiver. Finally, we show the improvement in ABER under varying turbulence and fog by adding cyclic redundancy check bits to data bits.