Cooperative spectrum sharing-based relaying protocols with wireless energy harvesting cognitive user (original) (raw)
Related papers
Cognitive spectrum sharing protocols for energy harvesting wireless sensor nodes
2016
Energy consumption is one of the primary concerns in the deployment of futuristic wireless sensor networks. On one hand due to advent of technologies such as Internet of Things (IoT), there has been tremendous growth in development of wireless sensor nodes, however, on the other hand these nodes are energy constrained, hence have limited lifetime. Energy harvesting from radio frequency (RF) signals has been proposed as a viable solution to alleviate this problem. Most of the recent work in the field of RF energy harvesting has involved cooperative relaying and cognitive radio networks. But now energy harvesting techniques have been employed to cooperative spectrum sharing framework as well. In this work, a hybrid time switching and power splitting spectrum sharing protocol for energy harvesting wireless sensor nodes is proposed. In the developed framework, an energy constrained sensor node adopts a time switching and power splitting based relaying protocol to harvest energy and spec...
In this paper, we propose an energy harvesting (EH)-based spectrum access model in cognitive radio (CR) network. In the proposed scheme, one of available secondary transmitters (STs) helps a primary transmitter (PT) forward primary signals to a primary receiver (PR). Via the cooperation, the selected ST finds opportunities to access licensed bands to transmit secondary signals to its intended secondary receiver (SR). Secondary users are assumed to be mobile, hence, optimization of energy consumption for these users is interested. The EH STs have to harvest energy from the PT's radio-frequency (RF) signals to serve the PT-PR communication as well as to transmit their signals. The proposed scheme employs incremental relaying technique in which the PR only requires the assistance from the STs when the transmission between PT and PR is not successful. Moreover , we also investigate impact of hardware impairments on performance of the primary and secondary networks. For performance evaluation, we derive exact and lower-bound expressions of outage probability (OP) over Rayleigh fading channel. Monte-Carlo simulations are performed to verify the theoretical results. The results present that the outage performance of both networks can be enhanced by increasing the number of the ST-SR pairs. In addition, the out-age performance of both primary and secondary networks is severely degraded with the increasing of hardware impairment level. It is also shown that fraction of time used for EH and positions of the secondary users significantly impact on the system performance.
Outage Analysis of Spectrum Sharing Energy Harvesting Cognitive Relays in Nakagami-m Channels
To appear in Proc. of IEEE GLOBECOM 2015
Energy harvesting (EH) cognitive relays are an exciting solution to the problem of inefficient use of spectrum while achieving green communications and spatial diversity. In a spectrum sharing scenario, we investigate the performance of a cognitive relay network, where a secondary source communicates with its destination over Nakagami-$m$ channels via decode-and-forward EH relays while maintaining the outage probability of the primary user below a predefined threshold. Specifically, we derive a closed-form expression for the secondary outage probability and show that it is a function of the probability of an EH relay having sufficient energy for relaying, which in turn, depends on the energy harvesting and consumption rates of the EH relay and the primary outage probability threshold. We also show that relaxing the primary outage constraint may not always benefit the cognitive EH relay network due to the limitations imposed on the relay's transmit power by the energy constraint.
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 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.
Energy Harvesting Based Multihop Relaying in Cognitive Radio Network
Wireless Personal Communications, 2017
In this paper, a multihop cognitive radio network using a series of multiple decode and forward (DF) energy harvesting relays is proposed to enhance the spectrum utilization and lifetime of the network. A time switching based energy harvesting scheme is considered for the DF relays. An analytical expression has been derived for evaluating the transmission power of the secondary source and secondary relays (SR) as well as SNR at SRs and secondary destination. The corresponding transmission power and signal to noise ratio (SNR) profiles are also analyzed for several numbers of relays under various locations of the primary transmitter (PT). An expression for a critical number of relays, for which the performance of the network is worst, has also been derived. It is seen that upto a critical number of relays the SNR decreases. However the SNR again increases with further increase in number of relays. Further secondary outage probabilities have been compared for several locations of PT. Analytical results following our development are presented and validated by MATLAB based simulation.
Wireless Energy Harvesting in a Cognitive Relay Network
Wireless energy harvesting is regarded as a promising energy supply alternative for energy-constrained wireless networks. In this paper, a new wireless energy harvesting protocol is proposed for an underlay cognitive relay network with multiple primary user (PU) transceivers. In this protocol, the secondary nodes can harvest energy from the primary network (PN) while sharing the licensed spectrum of the PN. In order to assess the impact of different system parameters on the proposed network, we first derive an exact expression for the outage probability for the secondary network (SN) subject to three important power constraints: 1) the maximum transmit power at the secondary source (SS) and at the secondary relay (SR), 2) the peak interference power permitted at each PU receiver, and 3) the interference power from each PU transmitter to the SR and to the secondary destination (SD). To obtain practical design insights into the impact of different parameters on successful data transmission of the SN, we derive throughput expressions for both the delay-sensitive and the delay-tolerant transmission modes. We also derive asymptotic closed-form expressions for the outage probability and the delay-sensitive throughput and an asymptotic analytical expression for the delay-tolerant throughput as the number of PU transceivers goes to infinity. The results show that the outage probability improves when PU transmitters are located near SS and sufficiently far from SR and SD. Our results also show that when the number of PU transmitters is large, the detrimental effect of interference from PU transmitters outweighs the benefits of energy harvested from the PU transmitters.
IEEE Access
Physical layer security is an important and timely topic in the research of future wireless systems and it constitutes a part of the Internet of Things (IoT) notion. IoT oriented systems are largely characterized by a stringent quality of service and enhanced security requirements, which comes at a cost of increased computational complexity that needs to be maintained within sustainable levels. In the present contribution, we investigate the physical-layer security of a dual-hop energy RF-Powered cognitive radio network over realistic multipath fading conditions. Assuming a spectrum sharing scenario, our analysis assumes that a source S communicates with a destination D with the aid of a multi-antenna relay R and in the presence of an eavesdropper E who is attempting to overhear the communication of both S-R and R-D links. The involved relay is powered by the renewable energy harvested from the signal sent by the source based on the power-splitting energy harvesting strategy. Furthermore, the relay uses a maximum ratio combining technique to process effectively the received signals. In addition, owing to the underlying strategy, both S and R adjust their respective transmit powers in order to avoid causing interference to the primary network. By considering both the independent identically distributed and the independent but not necessarily identically distributed flat Rayleigh fading channels, closed-form expressions for the secrecy outage probability are derived, based on which an asymptotic analysis is carried out. Our results quantify the impact of the main key system parameters and point out the optimal values ensuring a high-security performance of such a communication system. The validity of the derived results is verified extensively through comparisons with respective Monte Carlo simulation results and useful theoretical and technical insights are developed which are expected to be useful in the design of future cooperative CRNs. INDEX TERMS Cognitive radio network, energy harvesting, maximum ratio combining, physical layer security, power splitting, interference, secrecy outage probability.
Throughput and Outage Probability of Wireless Energy Harvesting Based Cognitive DF Relaying Network
Materials Today: Proceedings, 2017
This paper evaluates the throughput performance and outage probability of a secondary user (SU) in a decode-and-forward (DF) relaying network based on wireless energy harvesting under cognitive radio constraint. The energy constrained relay node first harvests energy through radio-frequency (RF) signals from the source node. Next, the relay node uses the harvested energy to forward the decoded source information to the destination node. The power transmitted by source and relay node is constrained by the tolerable interference threshold of the primary unit receiver. The source node transfers energy and information to the relay node through power splitting-based relaying (PSR). In PSR, the relay splits the received power for energy harvesting and information processing. The interference caused by a primary unit transmitter at the SU relay and destination nodes is also considered. Considering wireless energy harvesting constraint at the relay node, we analyse the achievable throughput and outage performance of a cognitive DF relaying network. We study the impact of different system parameters such as power splitting ratio, primary transmitter power and tolerable interference threshold of PU receiver on the throughput and outage performance of SU.
To appear in Proc. IEEE GLOBECOM 2015
We consider a spectrum sharing scenario, where a secondary network coexists with a primary network of multiple transceivers. The secondary network consists of an energy-constrained decode-and-forward secondary relay which assists the communication between a secondary transmitter and a destination in the presence of the interference from multiple primary transmitters. The secondary relay harvests energy from the received radio-frequency signals, which include the information signal from the secondary transmitter and the primary interference. The harvested energy is then used to decode the secondary information and forward it to the secondary destination. At the relay, we adopt a time switching policy due to its simplicity that switches between the energy harvesting and information decoding over time. Specifically, we derive a closed-form expression for the secondary outage probability under the primary outage constraint and the peak power constraint at both secondary transmitter and relay. In addition, we investigate the effect of the number of primary transceivers on the optimal energy harvesting duration that minimizes the secondary outage probability. By utilizing the primary interference as a useful energy source in the energy harvesting phase, the secondary network achieves a better outage performance.
Interference-Aided Energy Harvesting: Cognitive Relaying with Multiple Primary Transceivers
We consider a spectrum sharing scenario where a secondary transmitter (ST) communicates with its destination via a decode-and-forward secondary relay (SR) in the presence of interference from multiple primary transmitters. The SR harvests energy from received radio-frequency signals that include primary interference and uses it to forward the information to the secondary destination. The relay adopts a time switching policy that switches between energy harvesting and information decoding over the time. Under the primary outage constraints and the peak power constraints at both ST and SR, to determine the average secondary throughput, we derive exact analytical expressions for the secondary outage probability and the ergodic capacity, which characterize the delay-limited and the delay-tolerant transmissions, respectively. We also investigate the effects of the number of primary transceivers and the peak power constraints on the optimal energy harvesting time that maximizes the secondary throughput. By utilizing the primary interference as an energy source, the secondary network achieves a better throughput performance compared to the case where the primary interference is ignored for energy harvesting purpose. Finally, we consider a case where ST also harvests energy from primary transmissions and compare its throughput performance with that of the non-energy harvesting ST case.