452 research outputs found
DISTRIBUTED INTELLIGENT SPECTRUM MANAGEMENT IN COGNITIVE RADIO AD HOC NETWORKS
The rapid growth of the number of wireless devices has brought an exponential increase in the demand of the radio spectrum. However, according to the Federal Communications Commission (FCC), almost all the radio spectrum for wireless com- munications has already been allocated. In addition, according to FCC, up to 85% of the allocated spectrum is underutilized due to the current fixed spectrum alloca- tion policy. To alleviate the spectrum scarcity problem, FCC has suggested a new paradigm for dynamically accessing the allocated spectrum. Cognitive radio (CR) technology has emerged as a promising solution to realize dynamic spectrum access (DSA). With the capability of sensing the frequency bands in a time and location- varying spectrum environment and adjusting the operating parameters based on the sensing outcome, CR technology allows an unlicensed user to exploit the licensed channels which are not used by licensed users in an opportunistic manner.
In this dissertation, distributed intelligent spectrum management in CR ad hoc networks is explored. In particular, four spectrum management issues in CR ad hoc networks are investigated: 1) distributed broadcasting in CR ad hoc networks; 2) distributed optimal HELLO message exchange in CR ad hoc networks; 3) distributed protocol to defend a particular network security attack in CR ad hoc networks; and 4) distributed spectrum handoff protocol in CR ad hoc networks. The research in this dissertation has fundamental impact on CR ad hoc network establishment, net- work functionality, network security, and network performance. In addition, many of the unique challenges of distributed intelligent spectrum management in CR ad hoc networks are addressed for the first time in this dissertation. These challenges are extremely difficult to solve due to the dynamic spectrum environment and they have significant effects on network functionality and performance. This dissertation
is essential for establishing a CR ad hoc network and realizing networking protocols for seamless communications in CR ad hoc networks. Furthermore, this dissertation provides critical theoretical insights for future designs in CR ad hoc networks
Intelligent spectrum management techniques for wireless cognitive radio networks
PhD ThesisThis thesis addresses many of the unique spectrum management chal-
lenges in CR networks for the rst time. These challenges have a vital
e ect on the network performance and are particularly di cult to solve
due to the unique characteristics of CR networks. Speci cally, this thesis
proposes and investigates three intelligent spectrum management tech-
niques for CR networks. The issues investigated in this thesis have a
fundamental impact on the establishment, functionality and security of
CR networks.
First, an intelligent primary receiver-aware message exchange protocol
for CR ad hoc networks is proposed. It considers the problem of alleviat-
ing the interference collision risk to primary user communication, explic-
itly to protect primary receivers that are not detected during spectrum
sensing. The proposed protocol achieves a higher measure of safeguard-
ing. A practical scenario is considered where no global network topology
is known and no common control channel is assumed to exist.
Second, a novel CR broadcast protocol (CRBP) to reliably disseminate
the broadcast messages to all or most of the possible CR nodes in the
network is proposed. The CRBP formulates the broadcast problem as a
bipartite-graph problem. Thus, CRBP achieves a signi cant successful
delivery ratio by connecting di erent local topologies, which is a unique
feature in CR ad hoc networks.
Finally, a new defence strategy to defend against spectrum sensing data
falsi cation attacks in CR networks is proposed. In order to identify
malicious users, the proposed scheme performs multiple veri cations of
sensory data with the assistance of trusted nodes.Higher Committee For Education Devel-
opment in Iraq (HCED-Iraq
Mobile Ad-Hoc Networks
Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks
Cognitive radio network in vehicular ad hoc network (VANET): a survey
Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications
Communication Primitives in Cognitive Radio Networks
Cognitive radio networks are a new type of multi-channel wireless network in
which different nodes can have access to different sets of channels. By
providing multiple channels, they improve the efficiency and reliability of
wireless communication. However, the heterogeneous nature of cognitive radio
networks also brings new challenges to the design and analysis of distributed
algorithms.
In this paper, we focus on two fundamental problems in cognitive radio
networks: neighbor discovery, and global broadcast. We consider a network
containing nodes, each of which has access to channels. We assume the
network has diameter , and each pair of neighbors have at least ,
and at most , shared channels. We also assume each node has at
most neighbors. For the neighbor discovery problem, we design a
randomized algorithm CSeek which has time complexity
. CSeek is flexible and robust,
which allows us to use it as a generic "filter" to find "well-connected"
neighbors with an even shorter running time. We then move on to the global
broadcast problem, and propose CGCast, a randomized algorithm which takes
time. CGCast uses
CSeek to achieve communication among neighbors, and uses edge coloring to
establish an efficient schedule for fast message dissemination.
Towards the end of the paper, we give lower bounds for solving the two
problems. These lower bounds demonstrate that in many situations, CSeek and
CGCast are near optimal
Cognitive radio network in vehicular ad hoc network (VANET): a survey
Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications
Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges
With the rapid development of marine activities, there has been an increasing
number of maritime mobile terminals, as well as a growing demand for high-speed
and ultra-reliable maritime communications to keep them connected.
Traditionally, the maritime Internet of Things (IoT) is enabled by maritime
satellites. However, satellites are seriously restricted by their high latency
and relatively low data rate. As an alternative, shore & island-based base
stations (BSs) can be built to extend the coverage of terrestrial networks
using fourth-generation (4G), fifth-generation (5G), and beyond 5G services.
Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs.
Despite of all these approaches, there are still open issues for an efficient
maritime communication network (MCN). For example, due to the complicated
electromagnetic propagation environment, the limited geometrically available BS
sites, and rigorous service demands from mission-critical applications,
conventional communication and networking theories and methods should be
tailored for maritime scenarios. Towards this end, we provide a survey on the
demand for maritime communications, the state-of-the-art MCNs, and key
technologies for enhancing transmission efficiency, extending network coverage,
and provisioning maritime-specific services. Future challenges in developing an
environment-aware, service-driven, and integrated satellite-air-ground MCN to
be smart enough to utilize external auxiliary information, e.g., sea state and
atmosphere conditions, are also discussed
Cognitive radio network in vehicular ad hoc network (VANET): a survey
Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications
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