10,693 research outputs found
RF-Powered Cognitive Radio Networks: Technical Challenges and Limitations
The increasing demand for spectral and energy efficient communication
networks has spurred a great interest in energy harvesting (EH) cognitive radio
networks (CRNs). Such a revolutionary technology represents a paradigm shift in
the development of wireless networks, as it can simultaneously enable the
efficient use of the available spectrum and the exploitation of radio frequency
(RF) energy in order to reduce the reliance on traditional energy sources. This
is mainly triggered by the recent advancements in microelectronics that puts
forward RF energy harvesting as a plausible technique in the near future. On
the other hand, it is suggested that the operation of a network relying on
harvested energy needs to be redesigned to allow the network to reliably
function in the long term. To this end, the aim of this survey paper is to
provide a comprehensive overview of the recent development and the challenges
regarding the operation of CRNs powered by RF energy. In addition, the
potential open issues that might be considered for the future research are also
discussed in this paper.Comment: 8 pages, 2 figures, 1 table, Accepted in IEEE Communications Magazin
Interference-Assisted Wireless Energy Harvesting in Cognitive Relay Network with Multiple Primary Transceivers
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.Comment: 6 pages, 5 figures, To be presented at IEEE GLOBECOM 201
Cooperation and Underlay Mode Selection in Cognitive Radio Network
In this research, we proposes a new method for cooperation and underlay mode
selection in cognitive radio networks. We characterize the maximum achievable
throughput of our proposed method of hybrid spectrum sharing. Hybrid spectrum
sharing is assumed where the Secondary User (SU) can access the Primary User
(PU) channel in two modes, underlay mode or cooperative mode with admission
control. In addition to access the channel in the overlay mode, secondary user
is allowed to occupy the channel currently occupied by the primary user but
with small transmission power. Adding the underlay access modes attains more
opportunities to the secondary user to transmit data. It is proposed that the
secondary user can only exploits the underlay access when the channel of the
primary user direct link is good or predicted to be in non-outage state.
Therefore, the secondary user could switch between underlay spectrum sharing
and cooperation with the primary user. Hybrid access is regulated through
monitoring the state of the primary link. By observing the simulation results,
the proposed model attains noticeable improvement in the system performance in
terms of maximum secondary user throughput than the conventional cooperation
and non-cooperation schemes
Full-Duplex Cooperative Cognitive Radio Networks with Wireless Energy Harvesting
This paper proposes and analyzes a new full-duplex (FD) cooperative cognitive
radio network with wireless energy harvesting (EH). We consider that the
secondary receiver is equipped with a FD radio and acts as a FD hybrid access
point (HAP), which aims to collect information from its associated EH secondary
transmitter (ST) and relay the signals. The ST is assumed to be equipped with
an EH unit and a rechargeable battery such that it can harvest and accumulate
energy from radio frequency (RF) signals transmitted by the primary transmitter
(PT) and the HAP. We develop a novel cooperative spectrum sharing (CSS)
protocol for the considered system. In the proposed protocol, thanks to its FD
capability, the HAP can receive the PT's signals and transmit energy-bearing
signals to charge the ST simultaneously, or forward the PT's signals and
receive the ST's signals at the same time. We derive analytical expressions for
the achievable throughput of both primary and secondary links by characterizing
the dynamic charging/discharging behaviors of the ST battery as a finite-state
Markov chain. We present numerical results to validate our theoretical analysis
and demonstrate the merits of the proposed protocol over its non-cooperative
counterpart.Comment: 6 pages, 3 figures, conferenc
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