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Advanced Routing Protocols for Satellite and Space NetworksChen, Chao 12 May 2005 (has links)
Satellite systems have the advantage of global coverage and offer a solution for providing broadband access to end users. Local terrestrial networks and terminals can be connected to the rest of the world over Low Earth Orbit (LEO) satellite networks simply by installing small
satellite interfaces. With these properties, satellite systems play a crucial role in the global Internet to support real-time and non-real-time applications. Routing in satellite networks, and the integration of satellite
networks and the terrestrial Internet are the key issues to support these services.
Furthermore, the developments in space technologies enable the realization of deep-space missions such as Mars exploration. The Interplanetary Internet is envisioned to provide communication services for scientific data delivery and navigation services for the explorer spacecrafts and orbiters of future
deep-space missions. The unique characteristics posed by deep-space communications call for different research approaches from those in
terrestrial networks.
The objective of this research is to develop advanced architectures and efficient routing protocols for satellite and space networks to support applications with different traffic types and heterogeneous quality-of-service
(QoS) requirements. Specifically, a new QoS-based routing algorithm (QRA) is proposed as a
connection-oriented routing scheme to support real-time multimedia applications in satellite networks. Next, the satellite grouping and routing protocol (SGRP) is presented as a
unicast routing protocol in a two-layer satellite IP network architecture. The border gateway protocol - satellite version (BGP-S) is then proposed as a unified routing protocol to accomplish the integration of the terrestrial and satellite IP networks at the network layer.
Finally, a new routing framework, called the space backbone routing (SBR), is introduced for routing through different autonomous regions in the Interplanetary Internet. SBR provides a self-contained and scalable solution to support different traffic types through the Interplanetary Internet.
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Communication and Coordination in Wireless Multimedia Sensor and Actor NetworksMelodia, Tommaso 03 July 2007 (has links)
Wireless Sensor and Actor Networks (WSANs) are distributed systems of heterogeneous
devices, referred to as sensors and actors, which sense, control, and interact with the physical environment.
Sensors are low-cost, low-power, multi-functional devices that communicate untethered
in short distances. Actors are resource-rich devices that collect and process sensor data and consequently
perform actions on the environment.
This thesis is concerned with coordination and communication problems in WSANs, in datacentric
and multimedia application scenarios. First, communication and coordination problems are
jointly addressed in a unifying framework for the case of static actors. A sensor-actor coordination
model is proposed, based on an event-driven partitioning paradigm. Sensors are partitioned into
different sets and each set is associated with a different actor. Data delivery trees are created to
optimally react to the event and timely deliver event data with minimum energy expenditure. The
optimal partitioning strategy is determined bymathematical programming, and a distributed solution
is also proposed. Furthermore, the actor-actor coordination problem is formulated as an optimal task
assignment problem, and a distributed solution of the problem based on an analogy with a one-shot
auction is presented.
Application scenarios for WSANs with mobile actors are then studied. A location management
scheme is introduced to handle the mobility of actors with minimal energy consumption for
resource-constrained sensors. The proposed scheme, which is the first localization scheme specifically
designed for WSANs, is shown to consistently reduce the energy consumption with respect to
existing localization services for ad hoc and sensor networks. An optimal energy-aware forwarding
rule is then derived for sensor-actor communication in fast varying Rayleigh channels. The proposed
scheme allows controlling the delay of the data-delivery process based on power control, and
reacts to network congestion by diverting traffic from congested to lightly-loaded actors. The mobility
of actors is coordinated to optimally accomplish application-specific tasks, based on a nonlinear
optimization model that accounts for location and capabilities of heterogeneous actors.
The research challenges for delivery of multimedia traffic in wireless sensor and actor networks
are then outlined. Finally, a cross-layer communication architecture based on Ultra Wide Band
communications is described, whose design objective is to reliably and flexibly deliver QoS to multimedia
applications in WSANs, by carefully leveraging and controlling interactions among layers
according to application requirements. Performance evaluation shows how the proposed solution
achieves the performance objectives of wireless sensor and actor networks.
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On Resource Allocation for Communication Systems with Delay and Secrecy ConstraintsBalasubramanian, Anantharaman 2009 December 1900 (has links)
This dissertation studies fundamental limits of modern digital communication
systems in presence/absence of delay and secrecy constraints.
In the first part of this dissertation, we consider a typical time-division wireless
communication system wherein the channel strengths of the wireless users vary with
time with a power constraint at the base station and which is not subject to any
delay constraint. The objective is to allocate resources to the wireless users in an
equitable manner so as to achieve a specific throughput. This problem has been
looked at in different ways by previous researchers. We address this problem by
developing a systematic way of designing scheduling schemes that can achieve any
point on the boundary of the rate region. This allows us to map a desired throughput
to a specific scheduling scheme which can then be used to service the wireless users.
We then propose a simple scheme by which users can cooperate and then show that a
cooperative scheduling scheme enlarges the achievable rate region. A simple iterative
algorithm is proposed to find the resource allocation parameters and the scheduling
scheme for the cooperative system.
In the second part of the dissertation, a downlink time-division wireless sys-
tem that is subject to a delay constraint is studied, and the rate region and optimal
scheduling schemes are derived. The result of this study concludes that the achievable throughput of users decrease as the delay constraint is increased. Next, we consider
a problem motivated by cognitive radio applications which has been proposed as a
means to implement efficient reuse of the licensed spectrum. Previous research on this
topic has focussed largely on obtaining fundamental limits on achievable throughput
from a physical layer perspective. In this dissertation, we study the impact of im-
posing Quality of Service constraints (QoS) on the achievable throughput of users.
The result of this study gives insights on how the cognitive radio system needs to be
operated in the low and high QoS constraint regime.
Finally, the third part of this dissertation is motivated by the need for commu-
nicating information not only reliably, but also in a secure manner. To this end, we
study a source coding problem, wherein multiple sources needs to be communicated
to a receiver with the stipulation that there is no direct channel from the transmitter
to the receiver. However, there are many \agents" that can help carry the information
from the transmitter to the receiver. Depending on the reliability that the transmit-
ter has on each of the agents, information is securely encoded by the transmitter and
given to the agents, which will be subsequently given to the receiver. We study the
overhead that the transmitter has to incur for transmitting the information to the
receiver with the desired level of secrecy. The rate region for this problem is found
and simple achievable schemes are proposed. The main result is that, separate secure
coding of sources is optimal for achieving the sum-rate point for the general case of
the problem and the rate region for simple case of this problem.
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Evaluation Of Core Stateless Guaranteed Fair Network ArchitectureAkbas, Mustafa Ilhan 01 December 2006 (has links) (PDF)
The problem of providing Quality of Service (QoS) in the Internet has been an extremely active area of research and various mechanisms have been proposed related to this subject. Developing network applications have requirements such as bounded delay, jitter, minimum bandwidth and maximum loss rate. There is also a need to support large bandwidth networks because of growing link speeds. Previous QoS efforts did not fully satisfy all these needs of future networks but more recent approaches aim to be both scalable and rich in the provision of guaranteed services. Consequently core-stateless systems received much attention in recent years because of their scalability in supporting per-flow QoS. The property of not maintaining any per-flow state in the core routers is known as being core-stateless. In this thesis study, the need for core-stateless network architectures is pointed out and a literature survey about these schemes is carried out. Core-Stateless Guaranteed Fair (CSGF) network architecture, which provides deterministic fairness guarantees in a work-conserving manner, is selected and evaluated. Simulation studies about stateful Virtual Clock (VC) algorithm and CSGF&rsquo / s sub-protocols Core-Stateless Virtual Clock (CSVC), Core-Stateless Guaranteed Throughput (CSGT) and Core-Stateless Guaranteed Fairness (CSGF) are presented. Finally, the deficiencies in fairness of CSGF are demonstrated.
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Security And Quality Of Service For Wireless Sensor NetworksTomur, Emrah 01 February 2008 (has links) (PDF)
Security and quality of service (QoS) issues in cluster-based wireless sensor networks are investigated. The QoS perspective is mostly at application level consisting of four attributes, which are spatial resolution, coverage, system
lifetime and packet loss due to collisions. The addressed security aspects are message integrity and authentication. Under this scope, the interactions between security and service quality are analyzed with particular emphasis on the tradeoff between security and spatial resolution for channel capacity. The optimal security and spatial resolution levels which yield the best tradeoff are determined.
In addition, a control strategy is proposed to achieve the desired quality of service and security levels during the entire operation of a cluster-based sensor network. Compared to the existing studies, the proposed method is simpler and has superior performance.
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Quality Of Service Aware Dynamic Admission Control In Ieee 802.16j Non-transparent Relay NetworksKilic, Eda 01 February 2010 (has links) (PDF)
Today, telecommunication is improving rapidly. People are online anywhere anytime. Due to
increasing demand in communication, wireless technologies are progressing quickly trying to
provide more services in a wide range. In order to address mobility and connectivity requirements
of users in wide areas, Worldwide Interoperability for Microwave Access (Wimax) has
been introduced as a forth generation telecommunication technology.
Wimax, which is also called Metropolitan Area Network (MAN), is based on IEEE 802.16
standard where a Base Station (BS) provides last mile broadband wireless access to the end
users known as Mobile Stations (MS). However, in places where high constructions exist,
the signal rate between MS and BS decreases or even the signal can be lost completely due
to shadow fading. As a response to this issue, recently an intermediate node specification,
namely Relay Station, has been defined in IEEE 802.16j standard for relaying, which provides
both throughput enhancement and coverage extension. However, this update has introduced a
new problem / call admission control in non-transparent relay networks that support coverage
extension.
In this thesis, a Quality of Service (QoS) aware dynamic admission control algorithm for
IEEE 802.16j non-transparent relay networks is introduced. Our objectives are admitting
more service flows, utilizing the bandwidth, giving individual control to each relay station
(RS) on call acceptance and rejection, and finally not affecting ongoing service flow quality in
an RS due to the dense population of service flows in other RSs. The simulation results show
that the proposed algorithm outperforms the other existing call admission control algorithms.
Moreover, this algorithm can be interpreted as pioneer call admission control algorithm in
IEEE 802.16j non-transparent networks.
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Automatic Quality Of Service (qos) Evaluation For Domain Specific Web Service Discovery FrameworkAskaroglu, Emra 01 June 2011 (has links) (PDF)
Web Service technology is one of the most rapidly developing contemporary technologies.
Nowadays, Web Services are being used by a large number of projects and academic studies
all over the world. As the use of Web service technology is increasing, it becomes harder
to find the most suitable web service which meets the Quality of Service (QoS) as well as
functional requirements of the user. In addition, quality of the web services (QoS) that take
part in the software system becomes very important. In this thesis, we develop a method to
track the QoS primitives of Web Services and an algorithm to automatically calculate QoS
values for Web Services. The proposed method is realized within a domain specific web
service discovery system, namely DSWSD-S, Domain Specific Web Service Discovery with
Semantics. This system searches the Internet and finds web services that are related to a
domain and calculates QoS values through some parameters. When a web service is queried,
our system returns suitable web services with their QoS values. How to calculate, keep track
of and store QoS values constitute the main part of this study.
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Query Interface And Query Language For Domain Specific Web Service Discovery SystemOzdil, Hilal 01 September 2011 (has links) (PDF)
As the number of the published web services increase, discovery of the web services with the desired functionality and quality is becoming a challenging process. Selecting the appropriate web services among the ones that oer the same functionality is also a challenging task. The web service repositories like UDDI (Universal Description Discovery and Integration) support only the syntactic searchs. Quality of service parameters for the published web services can not be queried over these repositories. We have proposed a query language that aims to overcome these problems. It enables its users to query the web services both syntactically and semantically. We also allow the users to specify the quality of service criteria which the desired web services should satisfy. We have developed a graphical query interface to assist the users in query sentence formulation process. The proposed work is developed as a submodule of the Domain Specific Web Service Discovery with Semantics (DSWSD-S) System. Aforementioned query language and the query interface are explained in detail in this thesis.
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Qos-aware Service Selection For Web Service CompositionAbdyldaeva, Rahat 01 June 2012 (has links) (PDF)
Composition of web services is one of the flexible and easiest approaches for
creating composite services that fulfill complex tasks. Together with providing
convenience in creation of new software applications, service composition has
various challenges. One of them is the satisfaction of user-defined Quality of Service
(QoS) requirements while selecting services for a composition. Load balancing issue
is another challenge as uncontrolled workload may lead to violation of service
providers&rsquo / QoS declarations. This thesis work proposes a QoS aware method for
optimum service composition while taking into account load balancing. M/M/C
queuing model is utilized for the individual services to determine sojourn time
distribution for possible compositions. Percentile of the execution time, price and
availability are considered as QoS parameters. Proposed algorithm selects the
optimum composition according to QoS constraints and utility provided by the
services. The performance of the method is evaluated by custom simulation software
and is compared to two other methods, random selection and average execution timebased
optimal service selection.
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Adaptive Quality of Service Mechanisms in Wireless NetworksLin, Yuh-Chung 07 July 2008 (has links)
The increasing popularity of wireless networks over the last years indicates that there will be a demand for communicating devices providing high capacity communication together with QoS requirements. There are two types of wireless networks, infrastructure and Ad Hoc networks. The variation of topology caused by the mobility of hosts in the Ad Hoc networks results in a long latency, large jitter and low throughput. In infrastructure wireless networks, a base station (BS) or an Access Point (AP) is in charge of the data transmission. Therefore, the wireless hop can be considered as another hop of the transmission path. With the rapid growth of wireless traffics, the future wireless network is expected to provide services for heterogeneous data traffics with different quality of service requirements. Most proposed schemes do not have mechanisms to adapt to environment changes. In real situation, bandwidths, error rates, and loss rates of wireless links vary frequently.
The QoS issues are very important in modern networks. There are many proposed service models and mechanisms to support QoS in wireline networks. Most of these QoS mechanisms are not suitable for direct application to the wireless network because of the characteristics of wireless communication which includes: 1) high error rates and bursty errors, 2) location-dependent and time-varying wireless channel capacity, 3) scarce bandwidth, 4) user mobility, and 5) power constraints of the mobile hosts. All of these above characteristics make the development of QoS in wireless networks very difficult and challenging.
We try to cope with the bandwidth variations caused by the high error rate and bursty errors in wireless links, and the location-dependent and time-varying natures of wireless channel capacity. Furthermore, we expect to utilize the scarce wireless bandwidth more efficiently. In our proposed scheme, the higher priority flow is capable of broadcasting a message to inform the lower priority flows to change their priorities to adapt to environment variations. We will base on the differentiated service model and propose a Wireless Differentiation (WD) scheme for UDP flows and a Wireless Differentiation with Prioritized ACK (WDPA) scheme for connections with TCP flows which provide QoS support for IEEE 802.11b and do not change the basic access mechanism of IEEE 802.11b.
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