Tamaghna Acharya | Indian Institute of Engineering Science and Technology, Shibpur (original) (raw)

Papers by Tamaghna Acharya

Research paper thumbnail of Outage Analysis in DF Relay Assisted Two-Way Communication with RF Energy Harvesting

Research paper thumbnail of On Outage Analysis in Overlay CCRN With RF Energy Harvesting and Co-Channel Interference

This paper explores the impact of co-channel interference (CCI) on the link outage and radio freq... more This paper explores the impact of co-channel interference (CCI) on the link outage and radio frequency (RF) energy harvesting (EH). For analysis, co-operative cognitive radio network (CCRN) architecture is considered as system model that supports one-way primary user (PU) and two-way secondary user (SU) communications, using an overlay mode of spectrum sharing. Closed form outage expressions are derived for both PU and SU network in presence of multiple antennas at PUs and CCI at SUs. The effect of CCI on the system performance is studied with respect to interference-to-noise-ratio (INR), transmission power, number of antennas and number of CCI sources. Performance gains are found to achieve ~ 20% and ~ 15% for PU and SU outage in two antenna system over a single antenna one.

Research paper thumbnail of On Outage Analysis in SWIPT Enabled Bidirectional D2D Communications Using Spectrum Sharing in Cellular Networks

IEEE Transactions on Vehicular Technology, 2020

This paper explores a model on cooperative cognitive radio network (CCRN) to enable the in-band b... more This paper explores a model on cooperative cognitive radio network (CCRN) to enable the in-band bidirectional device-to-device (D2D) communications by sharing the licensed spectrum of cellular system (CS) in a 5G heterogeneous networks (HetNets) framework. In this model, cellular nodes (CNs) are modelled as primary users (PUs) and devices involved in D2D communications are referred as secondary users (SUs). The D2D pair, as unlicensed users, access to the licensed spectrum originally assigned to the CN pair while assuring relaying action to assist two-way communications between the CNs. Further, the D2D pair exploits the information-bearing radio frequency (RF) signals transmitted by the CNs to energize their transceivers, using the principle of simultaneous wireless information and power transfer (SWIPT). Closed form outage expressions of both cellular and D2D communications are derived. Simulation results are used to validate our analytical results. Simulation results show that about <inline-formula><tex-math notation="LaTeX">${\bf \sim 68\%}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">${\bf \sim 277\%}$</tex-math></inline-formula> gains are achieved by the proposed system in terms of spectrum efficiency and energy efficiency, respectively as compared to another prominent study on spectrum sharing enabled two-way PU and two-way SU communications.

Research paper thumbnail of On Outage Analysis in Cooperative Cognitive Radio Network with RF Energy Harvesting

2018 International Conference on Signal Processing and Communications (SPCOM), 2018

In this paper, we investigate the performance of a cooperative cognitive radio network which supp... more In this paper, we investigate the performance of a cooperative cognitive radio network which supports both spectrum sharing and radio frequency (RF) energy harvesting using power splitting relaying (PSR) protocol. The system model consists of a pair of primary users (PUs), each one equipped with multiple antennas and a pair of secondary users (SUs), each one equipped with a single antenna. The secondary transmit node harvests energy from the received signal of PUs and use this energy for forwarding the PUs signals and its own message signal. The exact closed form expressions of outage probability for PU and SU system outage are derived. A large set of simulation results are reported that validate the analytical outputs.

Research paper thumbnail of Outage Analysis in SWIPT Enabled Cooperative AF/DF Relay Assisted Two-Way Spectrum Sharing Communication

This paper reports relative performance of decode-and-forward (DF) and amplify-and-forward (AF) r... more This paper reports relative performance of decode-and-forward (DF) and amplify-and-forward (AF) relaying in a multi-antenna cooperative cognitive radio network (CCRN) that supports device-to-device (D2D) communications using spectrum sharing technique in cellular network. In this work, cellular system is considered as primary and internet of things devices (IoDs), engaged in D2D communications, are considered to be secondary system. The devices access the licensed spectrum by means of the cooperation in two-way primary communications. Furthermore, IoDs are energized by harvesting the energy from radio frequency (RF) signals, using simultaneous wireless information and power transfer (SWIPT) protocol. Closed form expressions of outage probability for both cellular and D2D communications are derived and the impact of various design parameters for both AF and DF relaying techniques are studied. Based on the simulation results, it is found that the proposed spectrum sharing protocol, fo...

Research paper thumbnail of Outage Analysis in SWIPT Enabled Spectrum Sharing D2D Communication for IoT Applications

This paper reports a relative performance analysis of decode-and-forward (DF) and amplify-and-for... more This paper reports a relative performance analysis of decode-and-forward (DF) and amplify-and-forward (AF) relaying in a multi-antenna cooperative cognitive radio network (CCRN) that supports device-to-device (D2D) communications using spectrum sharing technique in cellular network. In this work, cellular system is considered as primary and internet of things devices (IoDs), engaged in D2D communications, are considered as secondary system. The devices access the licensed spectrum by means of the cooperation in two-way primary communications. Furthermore, IoDs are energized through the harvesting of energy from radio frequency (RF) signals, using simultaneous wireless information and power transfer (SWIPT) protocol. Closed form expressions of the outage probability for both cellular and D2D communications are derived and the impact of various design parameters for both AF and DF relaying techniques are studied. Based on the simulation results, it is found that the proposed spectrum ...

Research paper thumbnail of Fairness in message delivery in delay tolerant networks

Wireless Networks, 2018

Rare existence of the end-to-end path and intermittent connectivity among the nodes are the key c... more Rare existence of the end-to-end path and intermittent connectivity among the nodes are the key characteristics of delay tolerant networks (DTNs). Such networks are potentially applicable in challenged environment like post-disaster situation, where traditional communication infrastructure is partially or fully absent. Significant research efforts are made to develop data forwarding schemes which are efficient in terms of delivery ratio in DTNs. However, fairness in message delivery is a less investigated topic in DTN routing. In most of the traditional data forwarding schemes, delivery of a message varies depending on its destination. Each destination in the network may not receive its intended messages with the same success rate. But in real-life applications, e.g. post-disaster environment, fair delivery of the messages to each destination is imperative for conducting relief operations properly. In this paper, we address the issue of fairness in message delivery in DTNs. In order to achieve fairness in message delivery, we analyze the influence of important parameters on successful message delivery. Based on this analysis, we design a metric for relay selection and subsequently propose a relay selection scheme for fair message delivery in DTNs. Performance of our proposed scheme is evaluated in ONE simulator considering realistic node-mobility map based on a recent post-disaster situation. Comparative results show that the proposed scheme achieves more impressive fairness in message delivery than the other competing schemes while achieving acceptable delivery ratio and low overhead ratio in the network.

Research paper thumbnail of Outage analysis in two-way communication with RF energy harvesting relay and co-channel interference

Transactions on Emerging Telecommunications Technologies, 2017

The study of relays with the scope of energy-harvesting (EH) looks interesting as a means of enab... more The study of relays with the scope of energy-harvesting (EH) looks interesting as a means of enabling sustainable, wireless communication without the need to recharge or replace the battery driving the relays. However, reliability of such communication systems becomes an important design challenge when such relays scavenge energy from the information bearing RF signals received from the source, using the technique of simultaneous wireless information and power transfer (SWIPT). To this aim, this work studies bidirectional communication in a decode-and-forward (DF) relay assisted cooperative wireless network in presence of co-channel interference (CCI). In order to quantify the reliability of the bidirectional communication systems, a closed form expression for the outage probability of the system is derived for both power splitting (PS) and time switching (TS) mode of operation of the relay. Simulation results are used to validate the accuracy of our analytical results and illustrate the dependence of the outage probability on various system parameters, like PS factor, TS factor, and distance of the relay from both the users. Results of performance comparison between PS relaying (PSR) and TS relaying (TSR) schemes are also presented. Besides, simulation results are also used to illustrate the spectral-efficiency and the energy-efficiency of the proposed system. The results show that, both in terms of spectralefficiency and the energy-efficiency, the two-way communication system in presence of moderate CCI power, performs better than the similar system without CCI. Additionally, it is also found that PSR is superior to TSR protocol in terms of peak energy-efficiency.

Research paper thumbnail of Social-based energy-aware multicasting in delay tolerant networks

Journal of Network and Computer Applications, 2017

In a post-disaster environment, traditional network infrastructure is mostly unavailable due to i... more In a post-disaster environment, traditional network infrastructure is mostly unavailable due to incidental destruction and damages. In such scenarios, delay/disruption tolerant networking may be considered as an alternative approach to meet the quintessential communication needs between the victims, field workers and centralized authority. In such applications, multicast communication is imperative because rescue and relief messages may often need to be shared among many volunteers. In this paper, we address the problem of relay selection for multicasting single and multiple data items in DTNs considering the application in disaster management. Both the single-data and multiple-data multicast problems are formulated as bi-objective optimization problems under the constraints of target delivery time, buffer space and residual energy levels of relay nodes. Both the problems are shown to be NP-hard. Hence, we propose two heuristic relay selection schemes exploiting social properties in DTNs. Theoretical analysis is performed for energy consumption and exhaustive simulation is carried out to evaluate performance of our proposed schemes in ONE simulator considering real-life data in post-disaster scenarios. Results show that our schemes are energy-saving thereby ensure longer network lifetime compared to other prominent schemes.

Research paper thumbnail of Energy Efficiency in Cooperative Cognitive Radio Network in the Presence of Malicious Users

IEEE Systems Journal, 2016

Energy efficiency (EE) in cooperative cognitive radio networks (CCRNs) enhances opportunistic dat... more Energy efficiency (EE) in cooperative cognitive radio networks (CCRNs) enhances opportunistic data transmission through efficient utilization of power. A novel CCRN with a frame structure accommodating cooperative spectrum sensing (CSS) and cooperation in primary user's (PU) transmission or opportunistic secondary users' (SU) transmission is considered aiming to maximize EE. A set of optimal values for spectrum sensing (SS) time, self, and cooperative transmission power gains are calculated under the constraints of SU power budget, PU detection probability, and SU and PU spectrum efficiency. The proposed system is further investigated in the presence of two separate malicious operations, namely PU emulation operation and spectrum sensing data falsification followed by their detection and weight allocation in data transmission of SU. The goal here is to analyze and evaluate the consequent gain in EE for the CCRN while maintaining the same SS reliability and target PU's transmission rate. Extensive results with a target set of parameters highlight the efficacy of the system.

Research paper thumbnail of Trade-off on spectrum-energy efficiency in cooperative cognitive radio networks

2016 International Conference on Signal Processing and Communications (SPCOM), 2016

The demand for high throughput at low power consumption requires spectrum efficient as well as en... more The demand for high throughput at low power consumption requires spectrum efficient as well as energy efficient design in next generation wireless networks. However, spectrum efficiency (SE) and energy efficiency (EE) can not be improved simultaneously. To this aim, in this work, the EE-SE trade-off issue is investigated in a cooperative cognitive radio network (CCRN). The secondary users (SUs) either cooperate in primary user's (PU) transmission when PU is detected active or proceed with their individual transmissions when PU is detected idle. The objective is to study the EE-SE trade-off in terms of cooperative and secondary transmission. A set of optimal values for spectrum sensing (SS) time, final decision threshold, self and cooperative transmission power gains are calculated under the constraints of SU power budget, PU detection probability, SU and PU spectrum efficiency. Numerical results highlight the efficacy of the proposed system and the issue of EE-SE trade-off is clearly demonstrated.

Research paper thumbnail of On optimal sensing time and power allocation for energy efficient cooperative cognitive radio networks

2015 IEEE International Conference on Advanced Networks and Telecommuncations Systems (ANTS), 2015

A cooperative cognitive radio (CR) network that accomplishes both spectrum sensing (SS) and shari... more A cooperative cognitive radio (CR) network that accomplishes both spectrum sensing (SS) and sharing is considered in this work. System model is assumed to be a cognitive ad hoc network that consists of multiple secondary transmitter (ST) and receiver (SR) pairs sharing transmission over a spectrum with a primary network of single transmitter-receiver pair. Based on SS outcome, secondary users (SUs) either cooperate in primary user's (PU) transmission or proceed with its own transmission. The overall goal is to maximize energy efficiency for SU networks in terms of self and cooperative transmission. A set of optimal values for sensing duration, self and cooperative transmission power gains are calculated under the constraints of PU detection probability, SU power budget, PU and SU throughput. A large set of simulation results highlight the optimal performance gain of the proposed system.

Research paper thumbnail of On optimal power allocation for joint spectral sensing and data transmission in CR networks

2015 38th International Conference on Telecommunications and Signal Processing (TSP), 2015

This paper proposes an optimal power allocation algorithm between a cognitive user (CU) and a pri... more This paper proposes an optimal power allocation algorithm between a cognitive user (CU) and a primary user (PU) in a power constrained channel. The typical underlay system is characterized by joint spectral sensing for detecting the presence of the PU along with the provision of simultaneous PU and CU transmission. The task is to determine the power sharing between PU and CU with an objective to maximize the probability of detection of PU by CU and CU data transmission jointly, while meeting the limits of total transmit power and threshold of PU throughput. Simulation results show that the proposed scheme provides better detection probability compared to equal power allocation and also better CU throughput maintaining the total power budget and PU throughput constraints. Gain in probability of detection by 3% and in CU throughput by 36% is seen for total power budget of 0 dBW.

Research paper thumbnail of Outage Minimized Joint Power and Channel Allocation in Multihop Cognitive Radio Networks: A Lifetime-Centric Approach

Wireless Personal Communications, 2015

This paper looks for an optimal solution to address joint power and channel allocation problem in... more This paper looks for an optimal solution to address joint power and channel allocation problem in a multihop cognitive radio network (CRN). The overall goal is to minimize the end-to-end outage probability of the CRN while meeting simultaneously total transmission power and interference constraints to primary user (PU). Two different forms of interference model, with and without considering spectral distance between PU and secondary user (SU) channels, are considered where the former again uses uniform and triangular probability density functions for determining interference to PU. The problem has been solved using standard technique of solving convex optimization problem (for power allocation) and weighted bipartite matching (for channel allocation). Furthermore, the proposed solution assumes that transmitting nodes are energy constrained. Hence, network lifetime improvement is an additional design challenge. Simulation results show that the proposed scheme not only minimizes outage probability better compared to existing power allocation strategies but also results in savings of SUs power consumption, which helps to extend network lifetime significantly. Keywords Cognitive radio networks Á Joint power and channel allocation Á Outage probability Á Average interference Á Network lifetime & Tamaghna Acharya

Research paper thumbnail of Energy Efficient Cognitive Radio System for Joint Spectrum Sensing and Data Transmission

IEEE Journal on Emerging and Selected Topics in Circuits and Systems, 2014

An energy-efficient cognitive radio system design is suggested that simultaneously meets spectrum... more An energy-efficient cognitive radio system design is suggested that simultaneously meets spectrum sensing reliability and secondary data transmission rate constraints. System model involves co-located multiple amplify-and-forward relays in single cognitive radio source-destination (S-D) environment with a primary focus on optimal relay power allocation strategy. The problem is mathematically formulated as minimization of total energy consumption under the constraints of sensing reliability (in terms of detection and false alarm probabilities), secondary user throughput and interference threshold to primary user. Then a cluster based nonequal relay power allocation is also suggested. Extensive simulation results illustrate the variation of the minimum energy consumption with the key system parameters.

Research paper thumbnail of Fuzzy C-Means Clustering in Energy Detection for Cooperative Spectrum Sensing in Cognitive Radio System

Lecture Notes in Computer Science, 2014

An energy detection based cooperative spectrum sensing approach using Fuzzy c-means clustering is... more An energy detection based cooperative spectrum sensing approach using Fuzzy c-means clustering is proposed in this work for cognitive radio system. The objective here is to categorize first the measured PU energy contents into multiple classes to highlight the relative degree in presence or absence of PU and Fuzzy c-means (FCM) algorithm is utilized for this purpose. A soft decision based spectrum sensing is proposed here to categorize the presence or absence of PU in four different classes which then develop individual binary decision functions. Resultant binary decision function is then developed using OR fusion rule. Simulation results highlight that the proposed scheme provides high detection probability at low diversity and less number of samples. The results are further compared with the performance of the conventional energy detector methods to highlight the significance of the proposed scheme.

Research paper thumbnail of On optimal relay power allocation in energy efficient cognitive radio networks

2014 International Conference on Signal Processing and Communications (SPCOM), 2014

An energy-efficient amplify-and-forward relay assisted cognitive radio system design is proposed ... more An energy-efficient amplify-and-forward relay assisted cognitive radio system design is proposed that simultaneously considers the issue of cooperative spectrum sensing and secondary data transmission. The problem is mathematically formulated as minimization of total energy consumption under the constraints of sensing reliability (in terms of detection and false alarm probabilities), secondary user throughput and interference threshold to primary user. Simulation results show that there exists an optimal relay power gain that minimizes energy consumption.

Research paper thumbnail of On optimal power allocation and relay assignment in multiuser cognitive radio networks

2014 International Conference on Signal Processing and Communications (SPCOM), 2014

This paper considers the problem of joint spectrum sensing and secondary data transmission in mul... more This paper considers the problem of joint spectrum sensing and secondary data transmission in multiuser, multirelay cognitive radio networks. An optimization framework has been developed for the selection of source nodes, relay assignment and power allocation with an aim to maximize the sum throughput of secondary transmission under the constraints of sum transmission power for secondary source nodes, number of relays and probability of detection of primary user's signal. A suboptimal scheme is then suggested to get rid of the high complexity of the optimal relay assignment scheme. Numerical results are presented to validate the proposed power allocation, optimal and sub-optimal relay assignment schemes for various values of probability of detection and total number of relays constraints.

Research paper thumbnail of Outage Analysis for SWIPT-Enabled Two-Way Cognitive Cooperative Communications

IEEE Transactions on Vehicular Technology, 2018

In this paper, we study a cooperative cognitive radio network (CCRN) where the secondary user-tra... more In this paper, we study a cooperative cognitive radio network (CCRN) where the secondary user-transmitter (SU-Tx) assists bi-directional communication between a pair of primary users (PUs) following the principle of two-way relaying. In return, it gets access to the spectrum of the PUs to enable its own transmission to SU-receiver (SU-Rx). Further, in order to support sustainable operation of the network, SU-Tx is assumed to harvest energy from the RF signals received from the PUs, using the technique of simultaneous wireless information and power transfer (SWIPT). Assuming a decode-and-forward behaviour and power-splitting based relaying protocol at SU-Tx, closed form expressions for outage probability of PU and SU are obtained. Simulation results validate our analytical results and illustrate spectrum-efficiency and energy-efficiency advantages of the proposed system over one-way relaying. KEYWORDS Cooperative cognitive radio network, simultaneous wireless information and power transfer, two-way relaying, decode-andforward relaying.

Research paper thumbnail of Multiple Disjoint Power Aware Minimum Connected Dominating Sets for Efficient Routing in Wireless Ad Hoc Network

2007 International Conference on Information and Communication Technology, 2007

Dominating set based routing is emerging as a promising approach for routing in ad hoc wireless n... more Dominating set based routing is emerging as a promising approach for routing in ad hoc wireless networks. A set is dominating if all the nodes in the network are either in the set or neighbors of nodes in the set. Power aware minimum connected dominating set refers to a minimum connected dominating set where energy levels of all dominator nodes

Research paper thumbnail of Outage Analysis in DF Relay Assisted Two-Way Communication with RF Energy Harvesting

Research paper thumbnail of On Outage Analysis in Overlay CCRN With RF Energy Harvesting and Co-Channel Interference

This paper explores the impact of co-channel interference (CCI) on the link outage and radio freq... more This paper explores the impact of co-channel interference (CCI) on the link outage and radio frequency (RF) energy harvesting (EH). For analysis, co-operative cognitive radio network (CCRN) architecture is considered as system model that supports one-way primary user (PU) and two-way secondary user (SU) communications, using an overlay mode of spectrum sharing. Closed form outage expressions are derived for both PU and SU network in presence of multiple antennas at PUs and CCI at SUs. The effect of CCI on the system performance is studied with respect to interference-to-noise-ratio (INR), transmission power, number of antennas and number of CCI sources. Performance gains are found to achieve ~ 20% and ~ 15% for PU and SU outage in two antenna system over a single antenna one.

Research paper thumbnail of On Outage Analysis in SWIPT Enabled Bidirectional D2D Communications Using Spectrum Sharing in Cellular Networks

IEEE Transactions on Vehicular Technology, 2020

This paper explores a model on cooperative cognitive radio network (CCRN) to enable the in-band b... more This paper explores a model on cooperative cognitive radio network (CCRN) to enable the in-band bidirectional device-to-device (D2D) communications by sharing the licensed spectrum of cellular system (CS) in a 5G heterogeneous networks (HetNets) framework. In this model, cellular nodes (CNs) are modelled as primary users (PUs) and devices involved in D2D communications are referred as secondary users (SUs). The D2D pair, as unlicensed users, access to the licensed spectrum originally assigned to the CN pair while assuring relaying action to assist two-way communications between the CNs. Further, the D2D pair exploits the information-bearing radio frequency (RF) signals transmitted by the CNs to energize their transceivers, using the principle of simultaneous wireless information and power transfer (SWIPT). Closed form outage expressions of both cellular and D2D communications are derived. Simulation results are used to validate our analytical results. Simulation results show that about <inline-formula><tex-math notation="LaTeX">${\bf \sim 68\%}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">${\bf \sim 277\%}$</tex-math></inline-formula> gains are achieved by the proposed system in terms of spectrum efficiency and energy efficiency, respectively as compared to another prominent study on spectrum sharing enabled two-way PU and two-way SU communications.

Research paper thumbnail of On Outage Analysis in Cooperative Cognitive Radio Network with RF Energy Harvesting

2018 International Conference on Signal Processing and Communications (SPCOM), 2018

In this paper, we investigate the performance of a cooperative cognitive radio network which supp... more In this paper, we investigate the performance of a cooperative cognitive radio network which supports both spectrum sharing and radio frequency (RF) energy harvesting using power splitting relaying (PSR) protocol. The system model consists of a pair of primary users (PUs), each one equipped with multiple antennas and a pair of secondary users (SUs), each one equipped with a single antenna. The secondary transmit node harvests energy from the received signal of PUs and use this energy for forwarding the PUs signals and its own message signal. The exact closed form expressions of outage probability for PU and SU system outage are derived. A large set of simulation results are reported that validate the analytical outputs.

Research paper thumbnail of Outage Analysis in SWIPT Enabled Cooperative AF/DF Relay Assisted Two-Way Spectrum Sharing Communication

This paper reports relative performance of decode-and-forward (DF) and amplify-and-forward (AF) r... more This paper reports relative performance of decode-and-forward (DF) and amplify-and-forward (AF) relaying in a multi-antenna cooperative cognitive radio network (CCRN) that supports device-to-device (D2D) communications using spectrum sharing technique in cellular network. In this work, cellular system is considered as primary and internet of things devices (IoDs), engaged in D2D communications, are considered to be secondary system. The devices access the licensed spectrum by means of the cooperation in two-way primary communications. Furthermore, IoDs are energized by harvesting the energy from radio frequency (RF) signals, using simultaneous wireless information and power transfer (SWIPT) protocol. Closed form expressions of outage probability for both cellular and D2D communications are derived and the impact of various design parameters for both AF and DF relaying techniques are studied. Based on the simulation results, it is found that the proposed spectrum sharing protocol, fo...

Research paper thumbnail of Outage Analysis in SWIPT Enabled Spectrum Sharing D2D Communication for IoT Applications

This paper reports a relative performance analysis of decode-and-forward (DF) and amplify-and-for... more This paper reports a relative performance analysis of decode-and-forward (DF) and amplify-and-forward (AF) relaying in a multi-antenna cooperative cognitive radio network (CCRN) that supports device-to-device (D2D) communications using spectrum sharing technique in cellular network. In this work, cellular system is considered as primary and internet of things devices (IoDs), engaged in D2D communications, are considered as secondary system. The devices access the licensed spectrum by means of the cooperation in two-way primary communications. Furthermore, IoDs are energized through the harvesting of energy from radio frequency (RF) signals, using simultaneous wireless information and power transfer (SWIPT) protocol. Closed form expressions of the outage probability for both cellular and D2D communications are derived and the impact of various design parameters for both AF and DF relaying techniques are studied. Based on the simulation results, it is found that the proposed spectrum ...

Research paper thumbnail of Fairness in message delivery in delay tolerant networks

Wireless Networks, 2018

Rare existence of the end-to-end path and intermittent connectivity among the nodes are the key c... more Rare existence of the end-to-end path and intermittent connectivity among the nodes are the key characteristics of delay tolerant networks (DTNs). Such networks are potentially applicable in challenged environment like post-disaster situation, where traditional communication infrastructure is partially or fully absent. Significant research efforts are made to develop data forwarding schemes which are efficient in terms of delivery ratio in DTNs. However, fairness in message delivery is a less investigated topic in DTN routing. In most of the traditional data forwarding schemes, delivery of a message varies depending on its destination. Each destination in the network may not receive its intended messages with the same success rate. But in real-life applications, e.g. post-disaster environment, fair delivery of the messages to each destination is imperative for conducting relief operations properly. In this paper, we address the issue of fairness in message delivery in DTNs. In order to achieve fairness in message delivery, we analyze the influence of important parameters on successful message delivery. Based on this analysis, we design a metric for relay selection and subsequently propose a relay selection scheme for fair message delivery in DTNs. Performance of our proposed scheme is evaluated in ONE simulator considering realistic node-mobility map based on a recent post-disaster situation. Comparative results show that the proposed scheme achieves more impressive fairness in message delivery than the other competing schemes while achieving acceptable delivery ratio and low overhead ratio in the network.

Research paper thumbnail of Outage analysis in two-way communication with RF energy harvesting relay and co-channel interference

Transactions on Emerging Telecommunications Technologies, 2017

The study of relays with the scope of energy-harvesting (EH) looks interesting as a means of enab... more The study of relays with the scope of energy-harvesting (EH) looks interesting as a means of enabling sustainable, wireless communication without the need to recharge or replace the battery driving the relays. However, reliability of such communication systems becomes an important design challenge when such relays scavenge energy from the information bearing RF signals received from the source, using the technique of simultaneous wireless information and power transfer (SWIPT). To this aim, this work studies bidirectional communication in a decode-and-forward (DF) relay assisted cooperative wireless network in presence of co-channel interference (CCI). In order to quantify the reliability of the bidirectional communication systems, a closed form expression for the outage probability of the system is derived for both power splitting (PS) and time switching (TS) mode of operation of the relay. Simulation results are used to validate the accuracy of our analytical results and illustrate the dependence of the outage probability on various system parameters, like PS factor, TS factor, and distance of the relay from both the users. Results of performance comparison between PS relaying (PSR) and TS relaying (TSR) schemes are also presented. Besides, simulation results are also used to illustrate the spectral-efficiency and the energy-efficiency of the proposed system. The results show that, both in terms of spectralefficiency and the energy-efficiency, the two-way communication system in presence of moderate CCI power, performs better than the similar system without CCI. Additionally, it is also found that PSR is superior to TSR protocol in terms of peak energy-efficiency.

Research paper thumbnail of Social-based energy-aware multicasting in delay tolerant networks

Journal of Network and Computer Applications, 2017

In a post-disaster environment, traditional network infrastructure is mostly unavailable due to i... more In a post-disaster environment, traditional network infrastructure is mostly unavailable due to incidental destruction and damages. In such scenarios, delay/disruption tolerant networking may be considered as an alternative approach to meet the quintessential communication needs between the victims, field workers and centralized authority. In such applications, multicast communication is imperative because rescue and relief messages may often need to be shared among many volunteers. In this paper, we address the problem of relay selection for multicasting single and multiple data items in DTNs considering the application in disaster management. Both the single-data and multiple-data multicast problems are formulated as bi-objective optimization problems under the constraints of target delivery time, buffer space and residual energy levels of relay nodes. Both the problems are shown to be NP-hard. Hence, we propose two heuristic relay selection schemes exploiting social properties in DTNs. Theoretical analysis is performed for energy consumption and exhaustive simulation is carried out to evaluate performance of our proposed schemes in ONE simulator considering real-life data in post-disaster scenarios. Results show that our schemes are energy-saving thereby ensure longer network lifetime compared to other prominent schemes.

Research paper thumbnail of Energy Efficiency in Cooperative Cognitive Radio Network in the Presence of Malicious Users

IEEE Systems Journal, 2016

Energy efficiency (EE) in cooperative cognitive radio networks (CCRNs) enhances opportunistic dat... more Energy efficiency (EE) in cooperative cognitive radio networks (CCRNs) enhances opportunistic data transmission through efficient utilization of power. A novel CCRN with a frame structure accommodating cooperative spectrum sensing (CSS) and cooperation in primary user's (PU) transmission or opportunistic secondary users' (SU) transmission is considered aiming to maximize EE. A set of optimal values for spectrum sensing (SS) time, self, and cooperative transmission power gains are calculated under the constraints of SU power budget, PU detection probability, and SU and PU spectrum efficiency. The proposed system is further investigated in the presence of two separate malicious operations, namely PU emulation operation and spectrum sensing data falsification followed by their detection and weight allocation in data transmission of SU. The goal here is to analyze and evaluate the consequent gain in EE for the CCRN while maintaining the same SS reliability and target PU's transmission rate. Extensive results with a target set of parameters highlight the efficacy of the system.

Research paper thumbnail of Trade-off on spectrum-energy efficiency in cooperative cognitive radio networks

2016 International Conference on Signal Processing and Communications (SPCOM), 2016

The demand for high throughput at low power consumption requires spectrum efficient as well as en... more The demand for high throughput at low power consumption requires spectrum efficient as well as energy efficient design in next generation wireless networks. However, spectrum efficiency (SE) and energy efficiency (EE) can not be improved simultaneously. To this aim, in this work, the EE-SE trade-off issue is investigated in a cooperative cognitive radio network (CCRN). The secondary users (SUs) either cooperate in primary user's (PU) transmission when PU is detected active or proceed with their individual transmissions when PU is detected idle. The objective is to study the EE-SE trade-off in terms of cooperative and secondary transmission. A set of optimal values for spectrum sensing (SS) time, final decision threshold, self and cooperative transmission power gains are calculated under the constraints of SU power budget, PU detection probability, SU and PU spectrum efficiency. Numerical results highlight the efficacy of the proposed system and the issue of EE-SE trade-off is clearly demonstrated.

Research paper thumbnail of On optimal sensing time and power allocation for energy efficient cooperative cognitive radio networks

2015 IEEE International Conference on Advanced Networks and Telecommuncations Systems (ANTS), 2015

A cooperative cognitive radio (CR) network that accomplishes both spectrum sensing (SS) and shari... more A cooperative cognitive radio (CR) network that accomplishes both spectrum sensing (SS) and sharing is considered in this work. System model is assumed to be a cognitive ad hoc network that consists of multiple secondary transmitter (ST) and receiver (SR) pairs sharing transmission over a spectrum with a primary network of single transmitter-receiver pair. Based on SS outcome, secondary users (SUs) either cooperate in primary user's (PU) transmission or proceed with its own transmission. The overall goal is to maximize energy efficiency for SU networks in terms of self and cooperative transmission. A set of optimal values for sensing duration, self and cooperative transmission power gains are calculated under the constraints of PU detection probability, SU power budget, PU and SU throughput. A large set of simulation results highlight the optimal performance gain of the proposed system.

Research paper thumbnail of On optimal power allocation for joint spectral sensing and data transmission in CR networks

2015 38th International Conference on Telecommunications and Signal Processing (TSP), 2015

This paper proposes an optimal power allocation algorithm between a cognitive user (CU) and a pri... more This paper proposes an optimal power allocation algorithm between a cognitive user (CU) and a primary user (PU) in a power constrained channel. The typical underlay system is characterized by joint spectral sensing for detecting the presence of the PU along with the provision of simultaneous PU and CU transmission. The task is to determine the power sharing between PU and CU with an objective to maximize the probability of detection of PU by CU and CU data transmission jointly, while meeting the limits of total transmit power and threshold of PU throughput. Simulation results show that the proposed scheme provides better detection probability compared to equal power allocation and also better CU throughput maintaining the total power budget and PU throughput constraints. Gain in probability of detection by 3% and in CU throughput by 36% is seen for total power budget of 0 dBW.

Research paper thumbnail of Outage Minimized Joint Power and Channel Allocation in Multihop Cognitive Radio Networks: A Lifetime-Centric Approach

Wireless Personal Communications, 2015

This paper looks for an optimal solution to address joint power and channel allocation problem in... more This paper looks for an optimal solution to address joint power and channel allocation problem in a multihop cognitive radio network (CRN). The overall goal is to minimize the end-to-end outage probability of the CRN while meeting simultaneously total transmission power and interference constraints to primary user (PU). Two different forms of interference model, with and without considering spectral distance between PU and secondary user (SU) channels, are considered where the former again uses uniform and triangular probability density functions for determining interference to PU. The problem has been solved using standard technique of solving convex optimization problem (for power allocation) and weighted bipartite matching (for channel allocation). Furthermore, the proposed solution assumes that transmitting nodes are energy constrained. Hence, network lifetime improvement is an additional design challenge. Simulation results show that the proposed scheme not only minimizes outage probability better compared to existing power allocation strategies but also results in savings of SUs power consumption, which helps to extend network lifetime significantly. Keywords Cognitive radio networks Á Joint power and channel allocation Á Outage probability Á Average interference Á Network lifetime & Tamaghna Acharya

Research paper thumbnail of Energy Efficient Cognitive Radio System for Joint Spectrum Sensing and Data Transmission

IEEE Journal on Emerging and Selected Topics in Circuits and Systems, 2014

An energy-efficient cognitive radio system design is suggested that simultaneously meets spectrum... more An energy-efficient cognitive radio system design is suggested that simultaneously meets spectrum sensing reliability and secondary data transmission rate constraints. System model involves co-located multiple amplify-and-forward relays in single cognitive radio source-destination (S-D) environment with a primary focus on optimal relay power allocation strategy. The problem is mathematically formulated as minimization of total energy consumption under the constraints of sensing reliability (in terms of detection and false alarm probabilities), secondary user throughput and interference threshold to primary user. Then a cluster based nonequal relay power allocation is also suggested. Extensive simulation results illustrate the variation of the minimum energy consumption with the key system parameters.

Research paper thumbnail of Fuzzy C-Means Clustering in Energy Detection for Cooperative Spectrum Sensing in Cognitive Radio System

Lecture Notes in Computer Science, 2014

An energy detection based cooperative spectrum sensing approach using Fuzzy c-means clustering is... more An energy detection based cooperative spectrum sensing approach using Fuzzy c-means clustering is proposed in this work for cognitive radio system. The objective here is to categorize first the measured PU energy contents into multiple classes to highlight the relative degree in presence or absence of PU and Fuzzy c-means (FCM) algorithm is utilized for this purpose. A soft decision based spectrum sensing is proposed here to categorize the presence or absence of PU in four different classes which then develop individual binary decision functions. Resultant binary decision function is then developed using OR fusion rule. Simulation results highlight that the proposed scheme provides high detection probability at low diversity and less number of samples. The results are further compared with the performance of the conventional energy detector methods to highlight the significance of the proposed scheme.

Research paper thumbnail of On optimal relay power allocation in energy efficient cognitive radio networks

2014 International Conference on Signal Processing and Communications (SPCOM), 2014

An energy-efficient amplify-and-forward relay assisted cognitive radio system design is proposed ... more An energy-efficient amplify-and-forward relay assisted cognitive radio system design is proposed that simultaneously considers the issue of cooperative spectrum sensing and secondary data transmission. The problem is mathematically formulated as minimization of total energy consumption under the constraints of sensing reliability (in terms of detection and false alarm probabilities), secondary user throughput and interference threshold to primary user. Simulation results show that there exists an optimal relay power gain that minimizes energy consumption.

Research paper thumbnail of On optimal power allocation and relay assignment in multiuser cognitive radio networks

2014 International Conference on Signal Processing and Communications (SPCOM), 2014

This paper considers the problem of joint spectrum sensing and secondary data transmission in mul... more This paper considers the problem of joint spectrum sensing and secondary data transmission in multiuser, multirelay cognitive radio networks. An optimization framework has been developed for the selection of source nodes, relay assignment and power allocation with an aim to maximize the sum throughput of secondary transmission under the constraints of sum transmission power for secondary source nodes, number of relays and probability of detection of primary user's signal. A suboptimal scheme is then suggested to get rid of the high complexity of the optimal relay assignment scheme. Numerical results are presented to validate the proposed power allocation, optimal and sub-optimal relay assignment schemes for various values of probability of detection and total number of relays constraints.

Research paper thumbnail of Outage Analysis for SWIPT-Enabled Two-Way Cognitive Cooperative Communications

IEEE Transactions on Vehicular Technology, 2018

In this paper, we study a cooperative cognitive radio network (CCRN) where the secondary user-tra... more In this paper, we study a cooperative cognitive radio network (CCRN) where the secondary user-transmitter (SU-Tx) assists bi-directional communication between a pair of primary users (PUs) following the principle of two-way relaying. In return, it gets access to the spectrum of the PUs to enable its own transmission to SU-receiver (SU-Rx). Further, in order to support sustainable operation of the network, SU-Tx is assumed to harvest energy from the RF signals received from the PUs, using the technique of simultaneous wireless information and power transfer (SWIPT). Assuming a decode-and-forward behaviour and power-splitting based relaying protocol at SU-Tx, closed form expressions for outage probability of PU and SU are obtained. Simulation results validate our analytical results and illustrate spectrum-efficiency and energy-efficiency advantages of the proposed system over one-way relaying. KEYWORDS Cooperative cognitive radio network, simultaneous wireless information and power transfer, two-way relaying, decode-andforward relaying.

Research paper thumbnail of Multiple Disjoint Power Aware Minimum Connected Dominating Sets for Efficient Routing in Wireless Ad Hoc Network

2007 International Conference on Information and Communication Technology, 2007

Dominating set based routing is emerging as a promising approach for routing in ad hoc wireless n... more Dominating set based routing is emerging as a promising approach for routing in ad hoc wireless networks. A set is dominating if all the nodes in the network are either in the set or neighbors of nodes in the set. Power aware minimum connected dominating set refers to a minimum connected dominating set where energy levels of all dominator nodes