14,146 research outputs found
Multi-Channel Cognitive Radio Networks: Modeling, Analysis and Synthesis
In this contribution, we establish a model for multichannel cognitive radio
networks (CRNs) using the theory of priority queues. This model enables us to
conduct a performance analysis in the most general form by the derivation of
the probability mass function (PMF) of queue length at the secondary users
(SUs). In the second part, a reverse problem is considered to answer the
important top-down question of whether a service requirement can be satisfied
in a multi-channel CRN knowing the network parameters and traffic situation
with respect to the SUs and the primary users (PUs). Terming this problem as
the network synthesis, a precise conservation law is obtained, which relates
the packet waiting times of both types of users, and based on which the
achievable region of the network is also determined. Lastly, by the
introduction of a mixed strategy, the conditions for the existence of an
optimal trade-off between the interference onto the PUs and the
quality-of-service of the SUs is shown, and the optimal mixed strategy is
obtained when those conditions are satisfied.Comment: Accepted in IEEE Journal on Selected Area in Communication
DSAT-MAC : Dynamic Slot Allocation based TDMA MAC protocol for Cognitive Radio Networks
Cognitive Radio Networks (CRN) have enabled us to efficiently reuse the
underutilized radio spectrum. The MAC protocol in CRN defines the spectrum
usage by sharing the channels efficiently among users. In this paper we propose
a novel TDMA based MAC protocol with dynamically allocated slots. Most of the
MAC protocols proposed in the literature employ Common Control Channel (CCC) to
manage the resources among Cognitive Radio (CR) users. Control channel
saturation in case of large number of CR users is one of the main drawbacks of
the CCC based MAC protocols. In contrast with CCC based MAC protocols, DSAT-MAC
protocol is based on the TDMA mechanism, without using any CCC for control
information exchange. The channels are divided into time slots and CR users
send their control or data packets over their designated slot. The protocol
ensures that no slot is left vacant. This guarantees full use of the available
spectrum. The protocol includes the provision for Quality of Service, where
real-time and safety critical data is transmitted with highest priority and
least delay. The protocol also ensures a fair sharing of available spectrum
among the CR users, with the mechanism to regulate the transmission of
malicious nodes. Energy saving techniques are also presented for longer life of
battery operated CR nodes. Theoretical analysis and simulations over ns-2 of
the proposed protocol reveal that the protocol performs better in various CR
adhoc network applications.Comment: 19 pages, 20 figures, Initial work in proc. of the Ninth IEEE
International Conference on Wireless and Optical Communications Networks
(IEEE WOCN-2012), Indore, INDIA, 20-22 September, 201
Joint Scheduling and Power-Control for Delay Guarantees in Heterogeneous Cognitive Radios
An uplink multi secondary user (SU) cognitive radio system having average
delay constraints as well as an interference constraint to the primary user
(PU) is considered. If the interference channels between the SUs and the PU are
statistically heterogeneous due to the different physical locations of the
different SUs, the SUs will experience different delay performances. This is
because SUs located closer to the PU transmit with lower power levels. Two
dynamic scheduling-and-power-allocation policies that can provide the required
average delay guarantees to all SUs irrespective of their locations are
proposed. The first policy solves the problem when the interference constraint
is an instantaneous one, while the second is for problems with long-term
average interference constraints. We show that although the average
interference problem is an extension to the instantaneous interference one, the
solution is totally different. The two policies, derived using the Lyapunov
optimization technique, are shown to be asymptotically delay optimal while
satisfying the delay and interference constraints. Our findings are supported
by extensive system simulations and shown to outperform existing policies as
well as shown to be robust to channel estimation errors.Comment: Transactions on Wireless Communications, 2016 Keywords: Cognitive
Radios, Delay Constraints, Resource allocation, Stochastic Optimization,
Online Algorithm, Lyapunov Optimization, Average Interference Constraint,
Priority Queues. arXiv admin note: substantial text overlap with
arXiv:1601.00608, arXiv:1512.0298
Performance Evaluation of QoS Parameters in Dynamic Spectrum Sharing for Heterogeneous Wireless Communication Networks
Cognitive radio nodes have been proposed as means to improve the spectrum
utilization. It reuses the spectrum of a primary service provider under the
condition that the primary service provider services are not harmfully
interrupted. A cognitive radio can sense its operating environment's conditions
and it is able to reconfigure itself and to communicate with other counterparts
based on the status of the environment and also the requirements of the user to
meet the optimal communication conditions and to keep quality of service (QoS)
as high as possible. The efficiency of spectrum sharing can be improved by
minimizing the interference. The Utility function that captures the cooperative
behavior to minimize the interference and the satisfaction to improve the
throughput is investigated. The dynamic spectrum sharing algorithm can maintain
the quality of service (QoS) of each network while the effective spectrum
utilisation is improved under a fluctuation traffic environment when the
available spectrum is limited.Comment: IJCSI International Journal of Computer Science Issues, Vol. 9, Issue
1, No 2, January 2012 ISSN (Online): 1694-0814 http://www.IJCSI.or
Queueing Analysis for Preemptive Transmission in Underlay Cognitive Radio Networks
In many cognitive radio applications, there are multiple types of message
queues. Existing queueing analysis works in underlay CR networks failed to
discuss packets heterogeneity. Therefore high priority packets with impatient
waiting time that have preemptive transmission opportunities over low class are
investigated. We model the system behavior as a M/M/1+GI queue which is
represented by a two dimensional state transition graph. The reneging
probability of high priority packets and the average waiting time in two-class
priority queues is analyzed. Simulation results demonstrate that the average
waiting time of high priority packets decreases with the growing interference
power threshold and the average waiting time of the low priority packet is
proportional to the arrival rate of the high priority packet. This work may lay
the foundation to design efficient MAC protocols and optimize long term system
performance by carefully choosing system parameters
Scheduling in Instantaneous-Interference-Limited CR Networks with Delay Guarantees
We study an uplink multi secondary user (SU) cognitive radio system having
average delay constraints as well as an instantaneous interference constraint
to the primary user (PU). If the interference channels from the SUs to the PU
have independent but not identically distributed fading coefficients, then the
SUs will experience heterogeneous delay performances. This is because SUs
causing low interference to the PU will be scheduled more frequently, and/or
allocated more transmission power than those causing high interference. We
propose a dynamic scheduling-and-power-control algorithm that can provide the
required average delay guarantees to all SUs as well as protecting the PU from
interference. Using the Lyapunov technique, we show that our algorithm is
asymptotically delay optimal while satisfying the delay and interference
constraints. We support our findings by extensive system simulations and show
the robustness of the proposed algorithm against channel estimation errors.Comment: arXiv admin note: substantial text overlap with arXiv:1410.746
Extended Delivery Time Analysis for Cognitive Packet Transmission with Application to Secondary Queuing Analysis
Cognitive radio transceiver can opportunistically access the underutilized
spectrum resource of primary systems for new wireless services. With interleave
implementation, the secondary transmission may be interrupted by the primary
user's transmission. To facilitate the delay analysis of such secondary
transmission for a fixed-size secondary packet, we study the resulting extended
delivery time that includes both transmission time and waiting time. In
particular, we derive the exact distribution function of extended delivery time
of secondary transmission for both continuous sensing and periodic sensing
cases. Selected numerical and simulation results are presented for illustrating
the mathematical formulation. Finally, we consider a generalized M/G/1 queue
set-up at the secondary user and formulate the closed-form expressions for the
expected delay with Poisson traffic. The analytical results will greatly
facilitate the design of the secondary system for particular target
application.Comment: 28 pages, 10 figures. arXiv admin note: substantial text overlap with
arXiv:1409.091
Application of Asynchronous Weak Commitment Search in Autonomous Quality of Service Provision in Cognitive Radio Networks
This article presents a distributed solution to autonomous quality of service
provision in cognitive radio networks. Specifically, cognitive STDMA and CDMA
communication networks are studied. Based on asynchronous weak commitment
search the task of QoS provision is distributed among different network nodes.
Simulation results verify this scheme converges very fast to optimal solution,
which makes it suitable for practical real time systems. This application of
artificial intelligence in wireless and mobile communications can be used in
home automation and networking, and vehicular technology. The generalizations
and extensions of this approach can be used in Long Term Evolution Self
Organizing Networks (LTE-SONs). In addition, it can pave the way for
decentralized and autonomous QoS provision in capillary networks that reach end
nodes at Internet of Things, where central management is either unavailable or
not efficient
On Green Energy Powered Cognitive Radio Networks
Green energy powered cognitive radio (CR) network is capable of liberating
the wireless access networks from spectral and energy constraints. The
limitation of the spectrum is alleviated by exploiting cognitive networking in
which wireless nodes sense and utilize the spare spectrum for data
communications, while dependence on the traditional unsustainable energy is
assuaged by adopting energy harvesting (EH) through which green energy can be
harnessed to power wireless networks. Green energy powered CR increases the
network availability and thus extends emerging network applications. Designing
green CR networks is challenging. It requires not only the optimization of
dynamic spectrum access but also the optimal utilization of green energy. This
paper surveys the energy efficient cognitive radio techniques and the
optimization of green energy powered wireless networks. Existing works on
energy aware spectrum sensing, management, and sharing are investigated in
detail. The state of the art of the energy efficient CR based wireless access
network is discussed in various aspects such as relay and cooperative radio and
small cells. Envisioning green energy as an important energy resource in the
future, network performance highly depends on the dynamics of the available
spectrum and green energy. As compared with the traditional energy source, the
arrival rate of green energy, which highly depends on the environment of the
energy harvesters, is rather random and intermittent. To optimize and adapt the
usage of green energy according to the opportunistic spectrum availability, we
discuss research challenges in designing cognitive radio networks which are
powered by energy harvesters
Probability Density Function Estimation in OFDM Transmitter and Receiver in Radio Cognitive Networks based on Recurrent Neural Network
The most important problem in telecommunication is bandwidth limitation due
to the uncontrolled growth of wireless technology. Deploying dynamic spectrum
access techniques is one of the procedures provided for efficient use of
bandwidth. In recent years, cognitive radio network introduced as a tool for
efficient use of spectrum. These radios are able to use radio resources by
recognizing surroundings via sensors and signal operations that means use these
resources only when authorized users do not use their spectrum. Secondary users
are unauthorized ones that must avoid from interferences with primary users
transmission. Secondary users must leave channel due to preventing damages to
primary users whenever these users discretion. In this article, spectrum
opportunities prediction based on Recurrent Neural Network for bandwidth
optimization and reducing the amount of energy by predicting spectrum holes
discovery for quality of services optimization proposed in OFDM-based cognitive
radio network based on probability density function. The result of the
simulation represent acceptable value of SNR and bandwidth optimization in
these networks that allows secondary users to taking spectrum and sending data
without collision and overlapping with primary users.Comment: OFDM, Cognitive Radio Networks, Recurrent Neural Network, Probability
Density Functio
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