Divyang Rawal

Bio: Divyang Rawal is an academic researcher from LNM Institute of Information Technology. The author has contributed to research in topics: MIMO & Noma. The author has an hindex of 4, co-authored 35 publications receiving 93 citations. Previous affiliations of Divyang Rawal include Electronics and Telecommunications Research Institute & Dhirubhai Ambani Institute of Information and Communication Technology.

Performance analysis at far and near user in NOMA based system in presence of SIC error

Abstract: Non-orthogonal multiple access (NOMA) scheme is an emerging 5G technology to improve upon the spectral efficiency. It can support more users than the number of available frequency-,time-, and code-domain resources. The innovation behind NOMA technology is to exploit non-orthogonal resource allocation at the cost of receiver complexity to mitigate the inter-user interference arising due to non-orthogonal signals. In this paper, we present performance analysis of downlink NOMA (DL-NOMA) system in presence of successive interference cancellation (SIC) error over Rayleigh fading channels. In particular, we derive the exact closed-form expressions of bit error rate (BER) at near-user (U1) and far-user (U2) for the considered DL-NOMA system. Besides, we also present the achievable rate analysis of the considered NOMA system and it is observed that its achievable rate is higher as compared to conventional orthogonal multiple access (OMA) schemes. Further, we also determine the optimized power allocation coefficient for the NOMA system. The analytical results are corroborated with the Monte-Carlo simulations. The simulation results are presented for different modulation schemes and for different NOMA scenarios. A close argument between the analytical and simulation results validate our analysis.

Performance Analysis of NOMA Assisted Underwater Visible Light Communication System

Abstract: In this letter, we present the analytical investigation of the non-orthogonal multiple access (NOMA) assisted underwater visible light communication (UWVLC) system. The proposed system can cater to the needs such as low latency, high reliability and high data rate underwater multicasting to the sensor nodes. The UWVLC link is characterized by Exponential-Generalized Gamma (EGG) distribution. In particular, we derive the exact closed-form expressions of average bit error rate (BER) and ergodic capacity for underwater NOMA users. Further to understand the impact of the underwater scenario over the system performance, the analysis is carried out for parameters such as air bubble levels, gradient temperature and salinity level of the water. The obtained results validate the feasibility of the proposed system model.

Performance Analysis of NOMA Assisted Mobile Ad Hoc Networks for Sustainable Future Radio Access

Abstract: In this paper, we consider the use of non-orthogonal multiple access (NOMA) assisted mobile ad-hoc networking (MANET) for sustainable future radio access. We analyze the performance of the considered NOMA based system over Nakagami-m fading channels for the downlink scenario. In particular, we derive the closed-form expression of bit-error rate (BER) at the end users supported by the ad-hoc networks cooperated through the near NOMA user as well as through the far NOMA user. Further, we also derive the closed-form expression for the ergodic capacity and packet error rate for the considered system. Based on the obtained results, the impact of the power allocation coefficient over the performance of the considered system is analyzed to determine the optimal power allocation coefficient. The analytical results are corroborated with the simulations for various parameters to validate the analysis. It is observed that the NOMA assisted MANET system outperforms the conventional orthogonal multiple access based system in terms of ergodic capacity.

NOMA assisted underwater visible light communication system with full-duplex cooperative relaying

Abstract: In this work, we propose a non-orthogonal multiple access (NOMA) assisted underwater visible light communication system (UWVLC) with full-duplex cooperative relaying (FDCR). The near NOMA user ( U 1 ) supports the FDCR phenomena to assist the NOMA far user ( U 2 ) with the information transmission. The UWVLC channels are assumed to be Exponential-Generalized Gamma (EGG) distributed. The exact analytical expressions of achievable outage probability are derived for both the NOMA users under the practical assumption of imperfect successive interference cancellation (SIC) and residual self-interference (RSI) due to FDCR. Besides, we also present the coverage probability and system outage probability of the considered FDCR based NOMA system. Further, the system's performance is examined for the distinct underwater scenarios like water salinity, gradient temperature and air bubble level (BL), so as to verify the system's viability.

Prioritized IEEE 802.15.4 for wireless sensor networks

Abstract: Wireless Sensor Network is application specific data centric networks, having application span ranging from house hold application to mission critical applications. Applications like fire detection require immediate attention from the base station. Further these networks are resource constrain networks which require efficient utilization of scare resources. IEEE 802.15.4 is one of the low power, low rate wireless personal area network standard which is specifically designed targeting resource constrain networks. IEEE 802.15.4 dose not support any prioritized scheme that creates hurdle when one uses it with mission critical applications. In our work we have extended IEEE 802.15.4 with explicit priority mechanism to adopt it for application specific prioritized packet delivery. Our simulation results of packet delivery, prioritized packet delivery and per bit energy consumption show that explicit prioritized mechanism out performs specified standard.

A Survey of Beacon-Enabled IEEE 802.15.4 MAC Protocols in Wireless Sensor Networks

Abstract: IEEE 802.15.4 is the de facto standard for Wireless Sensor Networks (WSNs) that outlines the specifications of the PHY layer and MAC sub-layer in these networks. The MAC protocol is needed to orchestrate sensor nodes access to the wireless communication medium. Although distinguished by a set of strengths that contributed to its popularity in various WSNs, IEEE 802.15.4 MAC suffers from several limitations that play a role in deteriorating its performance. Also, from a practical perspective, 80.15.4-based networks are usually deployed in the vicinity of other wireless networks that operate in the same ISM band. This means that 802.15.4 MAC should be ready to cope with interference from other networks. These facts have motivated efforts to devise improved IEEE 802.15.4 MAC protocols for WSNs. In this paper we provide a survey for these protocols and highlight the methodologies they follow to enhance the performance of the IEEE 802.15.4 MAC protocol.

On the Capacity of Decode-and-Forward Relaying over Rician Fading Channels

Abstract: In this letter, we derive the probability density function (PDF) and cumulative distribution function (CDF) of the minimum of two non-central Chi-square random variables with two degrees of freedom in terms of power series. With the help of the derived PDF and CDF, we obtain the exact ergodic capacity of the following adaptive protocols in a decode-and-forward (DF) cooperative system over dissimilar Rician fading channels: (i) constant power with optimal rate adaptation; (ii) optimal simultaneous power and rate adaptation; (iii) channel inversion with fixed rate. By using the analytical expressions of the capacity, it is observed that the optimal power and rate adaptation provides better capacity than the optimal rate adaptation with constant power from low to moderate signal-to-noise ratio values over dissimilar Rician fading channels. Despite low complexity, the channel inversion based adaptive transmission is shown to suffer from significant loss in capacity as compared to the other adaptive transmission based techniques over DF Rician channels.

Communication and networking technologies for UAVs: A survey

Abstract: With the advancement in drone technology, in just a few years, drones will be assisting humans in every domain. But there are many challenges to be tackled, communication being the chief one. This paper aims at providing insights into the latest UAV (Unmanned Aerial Vehicle) communication technologies through investigation of suitable task modules, antennas, resource handling platforms, and network architectures. Additionally, we explore techniques such as machine learning and path planning to enhance existing drone communication methods. Encryption and optimization techniques for ensuring long−lasting and secure communications, as well as for power management, are discussed. Moreover, applications of UAV networks for different contextual uses ranging from navigation to surveillance, URLLC (Ultra-reliable and low−latency communications), edge computing and work related to artificial intelligence are examined. In particular, the intricate interplay between UAV, advanced cellular communication, and internet of things constitutes one of the focal points of this paper. The survey encompasses lessons learned, insights, challenges, open issues, and future directions in UAV communications. Our literature review reveals the need for more research work on drone−to−drone and drone−to−device communications.

Communication and networking technologies for UAVs: A survey

Abstract: With the advancement in drone technology, in just a few years, drones will be assisting humans in every domain. But there are many challenges to be tackled, communication being the chief one. This paper aims at providing insights into the latest UAV (Unmanned Aerial Vehicle) communication technologies through investigation of suitable task modules, antennas, resource handling platforms, and network architectures. Additionally, we explore techniques such as machine learning and path planning to enhance existing drone communication methods. Encryption and optimization techniques for ensuring long lasting and secure communications, as well as for power management, are discussed. Moreover, applications of UAV networks for different contextual uses ranging from navigation to surveillance, URLLC (Ultra reliable and low latency communications), edge computing and work related to artificial intelligence are examined. In particular, the intricate interplay between UAV, advanced cellular communication, and internet of things constitutes one of the focal points of this paper. The survey encompasses lessons learned, insights, challenges, open issues, and future directions in UAV communications. Our literature review reveals the need for more research work on drone to drone and drone to device communications.

Maximum Likelihood Receiver for Multiple Channel Transmission Systems

Abstract: A maximum likelihood (ML) estimator for digital sequences disturbed by Gaussian noise, intersymbol interference (ISI) and interchannel interference (ICI) is derived. It is shown that the sampled outputs of the multiple matched filter (MMF) form a set of sufficient statistics for estimating the input vector sequence. Two ML vector sequence estimation algorithms are presented. One makes use of the sampled output data of the multiple whitened matched filter and is called the vector Viterbi algorithm. The other one is a modification of the vector Viterbi algorithm and uses directly the sampled output of the MMF. It appears that, under a certain condition, the error performance is asymptotically as good as if both ISI and ICI were absent.