6,959 research outputs found
Power Allocation and Cooperative Diversity in Two-Way Non-Regenerative Cognitive Radio Networks
In this paper, we investigate the performance of a dual-hop block fading
cognitive radio network with underlay spectrum sharing over independent but not
necessarily identically distributed (i.n.i.d.) Nakagami- fading channels.
The primary network consists of a source and a destination. Depending on
whether the secondary network which consists of two source nodes have a single
relay for cooperation or multiple relays thereby employs opportunistic relay
selection for cooperation and whether the two source nodes suffer from the
primary users' (PU) interference, two cases are considered in this paper, which
are referred to as Scenario (a) and Scenario (b), respectively. For the
considered underlay spectrum sharing, the transmit power constraint of the
proposed system is adjusted by interference limit on the primary network and
the interference imposed by primary user (PU). The developed new analysis
obtains new analytical results for the outage capacity (OC) and average symbol
error probability (ASEP). In particular, for Scenario (a), tight lower bounds
on the OC and ASEP of the secondary network are derived in closed-form. In
addition, a closed from expression for the end-to-end OC of Scenario (a) is
achieved. With regards to Scenario (b), a tight lower bound on the OC of the
secondary network is derived in closed-form. All analytical results are
corroborated using Monte Carlo simulation method
Packet Relaying Control in Sensing-based Spectrum Sharing Systems
Cognitive relaying has been introduced for opportunistic spectrum access
systems by which a secondary node forwards primary packets whenever the primary
link faces an outage condition. For spectrum sharing systems, cognitive
relaying is parametrized by an interference power constraint level imposed on
the transmit power of the secondary user. For sensing-based spectrum sharing,
the probability of detection is also involved in packet relaying control. This
paper considers the choice of these two parameters so as to maximize the
secondary nodes' throughput under certain constraints. The analysis leads to a
Markov decision process using dynamic programming approach. The problem is
solved using value iteration. Finally, the structural properties of the
resulting optimal control are highlighted
Resource Allocation in Wireless Networks with RF Energy Harvesting and Transfer
Radio frequency (RF) energy harvesting and transfer techniques have recently
become alternative methods to power the next generation of wireless networks.
As this emerging technology enables proactive replenishment of wireless
devices, it is advantageous in supporting applications with quality-of-service
(QoS) requirement. This article focuses on the resource allocation issues in
wireless networks with RF energy harvesting capability, referred to as RF
energy harvesting networks (RF-EHNs). First, we present an overview of the
RF-EHNs, followed by a review of a variety of issues regarding resource
allocation. Then, we present a case study of designing in the receiver
operation policy, which is of paramount importance in the RF-EHNs. We focus on
QoS support and service differentiation, which have not been addressed by
previous literatures. Furthermore, we outline some open research directions.Comment: To appear in IEEE Networ
On Information and Energy Cooperation in Energy Harvesting Cognitive Radio
This paper considers the cooperation between primary and secondary users at
information and energy levels when both users are energy harvesting nodes. In
particular, a secondary transmitter helps relaying the primary message, and in
turn, gains the spectrum access as a reward. Also, the primary transmitter
supplies energy to the secondary transmitter if the latter is
energy-constrained, which facilitates an uninterrupted cooperation. We address
this two-level cooperation over a finite horizon with the finite battery
constraint at the secondary transmitter. While promising the rate-guaranteed
service to both primary and secondary users, we aim to maximize the primary
rate. We develop an iterative algorithm that obtains the optimal offline power
policies for primary and secondary users. To acquire insights about the
structure of the optimal solution, we examine specific scenarios. Furthermore,
we investigate the effects of the secondary rate constraint and finite battery
on the primary rate and the probability of cooperation. We show that the joint
information and energy cooperation increases the chances of cooperation and
achieves significant rate gains over only information cooperation.Comment: 6 pages, 4 figures, to be presented in IEEE PIMRC 201
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