Aashish Mathur

Bio: Aashish Mathur is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Fading & Bit error rate. The author has an hindex of 12, co-authored 35 publications receiving 512 citations. Previous affiliations of Aashish Mathur include Birla Institute of Technology and Science & Indian Institutes of Technology.

BER of an optically pre-amplified FSO system under Málaga turbulence, pointing errors, and ASE noise

Abstract: The performance of a free space optical (FSO) communication system is significantly affected by atmospheric turbulence and pointing errors (PEs) apart from the additive noise which is assumed to be Gaussian. The Malaga or M-distribution encompasses various proposed statistical models for atmospheric turbulence in FSO systems. An optical pre-amplifier is an essential component of FSO systems for improving the receiver (Rx) sensitivity. However, optical pre-amplification results in amplified spontaneous emissions (ASE), which dominate the Rx thermal and shot noises. The square law photodetection process at the Rx in a FSO system necessitates the consideration of Chi-square statistics for the decision variable contrary to the Gaussian approximation that is widely used in the literature. In this paper, we evaluate the bit error rate (BER) performance of a FSO system assuming non-return-to-zero on-off keying modulation in the presence of ASE noise under M-turbulence and PEs. We also derive asymptotic BER expressions for the considered FSO system for large values of signal-to-noise ratio in terms of simple elementary functions. A further insight into the system is provided by performing the diversity analysis.

Game-Theoretical Analysis of PLC System Performance in the Presence of Jamming Attacks

Abstract: In this paper, we investigate the performance of power line communication (PLC) network in the presence of jamming attacks. The legitimate nodes of the PLC network try to communicate with the anchor node of the network while the jamming node attempts to degrade the system performance. The fading, attenuation and colored noise of the PLC channel with dependence on the frequency and transmission distance are taken into account. To investigate the jamming problem, we frame the adversarial interaction into a Bayesian game, where the PLC network tries to maximize the overall expected network capacity and the jammer node has the opposite goal. In the Bayesian game, both players have imperfect knowledge of their opponents. We study effects of total power available to the players on the equilibrium of the game by formulating it into zero-sum and non-zero-sum games, respectively. It is found that under some network setup, there exists a threshold power for which the actual gameplay of the legitimate nodes does not depend upon the actions of the jamming node, and vice versa. This allows us to choose the appropriate power allocation schemes given the total power and the action of the jamming node in some cases.

Performance analysis of coordinate interleaved PLC system with Rayleigh channel gain under Nakagami-m additive noise

Abstract: Power line communication (PLC) is an emerging field of communication that makes use of the existing power line infrastructure for the transmission of data and power. However, the presence of additive and multiplicative power line noises deteriorate the performance of a PLC system. Background and impulsive noises are the two main categories of additive noise, whereas channel gain accounts for the multiplicative noise. In this study, the authors propose coordinate interleaving (CI) technique and investigate its performance for a PLC system under the combined effect of Nakagami-m additive background noise and Rayleigh channel gain. They assume perfect channel state information at the transmitter and receiver of the PLC link. By interleaving the coordinates of the symbols sent over different channel realisations, CI results in significant improvement in the performance of a PLC system. Both the simulated and analytical results shown in this study reveal the effectiveness of the proposed technique in achieving better performance.

Performance of optically pre-amplified FSO system under ASE noise with pointing errors

Abstract: Optical pre-amplifier forms an important component of a free space optical (FSO) communication system for improving the receiver sensitivity. The use of an optical pre-amplifier results into amplified spontaneous emissions (ASE) which dominates the receiver thermal and shot noises. The square law photodetector at the receiver in a FSO system necessitates the consideration of Chi-square statistics for the decision variable contrary to the Gaussian approximation that is widely used in literature. In this paper, we evaluate the bit error rate performance of a FSO system assuming non-return-to-zero on-off keying modulation in the presence of ASE noise under the combined effect of very strong turbulence (modeled by negative exponential distribution) and pointing errors. A further insight into the system is provided by performing the diversity analysis.

Secrecy Analysis of DCSK-Based PLC Systems With Multiple Eavesdroppers

Abstract: In the past two decades, chaotic modulation schemes have drawn much attention for their significant advantages over other traditional modulation techniques. One of the noticeable advantages is the capability of providing secure communication in the presence of an eavesdropper. In this article, we study the physical layer security (PLS) performance of low-frequency power line communication (PLC) systems against multiple eavesdroppers by employing differential chaos shift keying based modulation technique. A wiretap power line channel model is investigated by considering two different cases: 1) when all the channels are assumed to be independent and identically distributed (IID) following Log-normal distribution; and 2) the wiretap channels are considered to be identical but correlated Log-normally distributed and independent of the main channel. Contemporaneously, the Bernoulli-Gaussian random process models the PLC noise. Further, a comprehensive PLS study of the considered PLC system is characterized in terms of the average secrecy capacity, secure outage probability, and strictly positive secrecy capacity. We also propose an algorithm to maximize the secrecy throughput under security and reliability constraints. Moreover, to obtain essential insights, we reveal the impact of various crucial parameters onto the proposed system.

Table Of Integrals Series And Products

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Physical-Layer Security in Space Information Networks: A Survey

Abstract: Research and processing development on satellite communications has strongly re-emerged in recent years. Following the prosperity of various wireless services provided by satellite communications, the security issue has raised growing concerns since the space information network is susceptible to be eavesdropped by illegal adversaries in such a large-scale wireless network. Recently, the physical-layer security (PLS) has emerged as an alternative security paradigm that explores the randomness of the wireless channel to achieve confidentiality and authentication. The success story of the PLS technique now spans a decade and thrives to provide a layer of defense in satellite communications. With this position, a comprehensive survey of satellite communications is conducted in this article with an emphasis on PLS. We first briefly introduce essential background and the view of the satellite Internet of Things (IoT), as well as discuss related research challenges faced by the emerging integrated network architecture. Then, we revisit the most popular satellite channel model influenced by many factors and list the commonly used secrecy performance metrics. Also, we provide an exhaustive review of state-of-the-art research activity on PLS in satellite communications, which we categorize by different architectures including land mobile satellite communication networks, hybrid satellite-terrestrial relay networks, and satellite-terrestrial integrated networks. In addition, a number of open research problems are identified as possible future research directions.

Hybrid PLC/Wireless Communication for Smart Grids and Internet of Things Applications

Abstract: This paper outlines important characteristics of hybrid power line/wireless data communication system for smart grid (SG) and Internet of Things (IoT) applications. Moreover, we discuss the hybrid systems advantages in comparison to nonhybrid ones. These advantages are demonstrated not only in the technical point of view, but also in the infrastructural perspective. Also, we highlight a connection between the capillarity of IoT and the communication infrastructure provided by SG. Furthermore, we address the environmental influence on wireless and power line communications. Additionally, we present ergodic achievable data rate expressions for the hybrid power line/wireless channel (HPWC) and hybrid power line/wireless single-relay channel (HSRC) and provide performance analyses by considering four different cases, which are associated with the relative relay position in the single-relay channel model. Based on numerical results, we show that HPWC and HSRC offer a more reliable data transmission path when compared to power line or wireless system working alone.

Physical Layer Security of Hybrid Satellite-FSO Cooperative Systems

Abstract: In this paper, we study the physical layer secrecy performance of a hybrid satellite and free-space optical (FSO) cooperative system. The satellite links are assumed to follow the shadowed-Rician fading distribution, and the channel of the terrestrial link between the relay and destination is assumed to experience the gamma-gamma fading. For the FSO communications, the effects of different types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection) as well as the pointing error are considered. We derive exact analytical expressions for the average secrecy capacity and secrecy outage probability (SOP) for both cases of amplify-and-forward (AF) and decode-and-forward (DF) relaying. The asymptotic analysis for the SOP is also conducted to provide more insights on the impact of FSO and satellite channels on secrecy performance. It is found that with the AF with fixed gain scheme, the secrecy diversity order of the investigated system is only dependent on the channel characteristics of the FSO link and the FSO detection type, whereas the secrecy diversity is zero when the relay node employs DF or AF with variable-gain schemes.

Physical Layer Security in Vehicular Networks with Reconfigurable Intelligent Surfaces

Abstract: This paper studies the physical layer security (PLS) of a vehicular network employing a reconfigurable intelligent surface (RIS). RIS technologies are emerging as an important paradigm for the realisation of smart radio environments, where large numbers of small, low-cost and passive elements, reflect the incident signal with an adjustable phase shift without requiring a dedicated energy source. Inspired by the promising potential of RIS-based transmission, we investigate two vehicular network system models: One with vehicle-to-vehicle communication with the source employing a RIS-based access point, and the other model in the form of a vehicular adhoc network (VANET), with a RIS-based relay deployed on a building. Both models assume the presence of an eavesdropper to investigate the average secrecy capacity of the considered systems. Monte-Carlo simulations are provided throughout to validate the results. The results show that performance of the system in terms of the secrecy capacity is affected by the location of the RIS-relay and the number of RIS cells. The effect of other system parameters such as source power and eavesdropper distances are also studied.