Computer network protocols

Wireless ad hoc networks (or simply ad hoc networks) are infrastructureless multihop
networks consisting of mobile or stationary wireless devices, which include mobile
ad hoc networks (MANETs) and wireless sensor networks (WSNs). These networks are
characterized by limited bandwidth and energy resources, frequent topology changes,
and a lack of central control. These characteristics lead to the research challenges of ad
hoc networks. The algorithms designed for ad hoc networks should be localized, selforganizing,
and energy efficient. A connected dominating set (CDS) is frequently used in
ad hoc networks as a virtual backbone to support efficient routing, service discovery, and
area monitoring. In addition, efficient broadcasting (i.e., finding a small set of forward
nodes to ensure full delivery) can be viewed as forming a CDS on-the-fly. The periodically
maintained virtual backbone is called a static CDS, and the temporarily formed
forward node set is called a dynamk CDS. For efficiency and robustness, the ideal CDS
construction algorithm is lightweight, has fast convergence, and minimizes the CDS size. Recently, due to some specific applications and new techniques, the concept of a connected
dominating set can be modified or further extended for more efficient usage.
This dissertation focuses on the variations with applications of the connected dominating
set, designing new concepts, and developing new algorithms for them. A review
of CDS construction algorithms for ad hoc networks has been provided at the beginning.
An efficient scheme, called Rule K, has been proposed for static CDS construction. Rule
K achieves a probabilistic constant upper bound on the expected CDS size, which is currently
the best known performance guarantee for localized CDS algorithms. Several CDS
algorithms are extended to generate the extended CDS, which exploits the cooperative
communication technique to further reduce the size of CDS. A k-coverage set is developed
for higher robustness. With the equipment of directional antennas , the transmission
can be restricted to some certain directions to reduce interference and energy consumption.
The corresponding directional CDS is discussed. Finally, a wireless sensor and actor
network (WSAN) is introduced and localized algorithms are designed for it.

In recent years, many protocols for efficient Multicasting have been proposed.
However, many of the Internet Service Providers (ISPs) are reluctant to use multicastenabled
routers in their networks. To provide such incentives, new protocols are
needed to improve the quality of their services. The challenge is to find a compromise
between allocating Bandwidth (BW) among different flows in a fair manner, and
favoring multicast sessions over unicast sessions. In addition, the overall higher level
of receiver satisfaction should be achieved.
In this dissertation, we propose three new innovative protocols to favor
multicast sessions over unicast sessions. Multicast Favored BW Allocation-
Logarithmic (MFBA-Log) and Multicast Favored BW Allocation-Linear (MFBALin)
protocols allocate BW proportional to the number of down stream receivers.
The proposed Multicast Reserved BW Allocation (MRBA) protocol allocates part of the BW in the links only to multicast sessions. Simulation results show the increase in
the overall level of Receiver Satisfaction in the network.

With the ever increasing demand for bandwidth intensive applications like video-ondemand,
interactive television services, high-defmition television (HDTV) and internet
telephony, the first mile network, referred to as the last mile network in the earlier stages
of its development, has proven to solve the "bottleneck" often experienced between users
and the central office. The Ethernet Passive Optical Network (EPON), developed by the
IEEE 802.3ah Task Force for Ethernet in the First Mile (EFM), resolves this bottleneck
by providing the user with a fiber optic link to the central office that has many
advantages, such as nearly infinite bandwidth, low cost, easy installation and immunity to
electromagnetic interference, and a saving of the need for powered components in the
signal path from the user to the switch. EPON s have proven to deliver the essential
services of voice, video, and data communications reliably, while at the same time
providing expected guarantees of the delivery of those services in terms of defined
Quality of Service measures (QOS). A continuous theme throughout EPON research has
been the study of efficient Dynamic Bandwidth Allocation (DBA) as a key factor in
achieving fairness in distributing bandwidth amongst remote network units.
This research investigates another factor and its effect on network performance and
service delivery: Cycle Demand Proportionality (CDP). By observing the patterns of
demand in the network on an individual network unit basis cycle after cycle, deductions
regarding load characteristics of some units over others can be made. Decisions can be make about subsequent grant allocations based on this factor and aim to achieve better
results in the process. Simulations of EPONs Lmder varying loads incorporating the usc of
CDP in conjunction with currently used DBA schemes are made and results are analyzed.
A major contribution of this research is a new bandwidth allocation algorithm that gives
improved performance in terms of packet delay versus offered load. Performance metrics
are compared against two common bandwidth allocation algorithms: Interleaved Polling
with Adaptive Cycle Time (IPACT) and Cyclic Polling (CP). Additional results also
include improvements in packet loss and throughput.
The data that represents traffic for this network has two properties, self-similarity and
long range dependency. Plotting the auto-covariance, auto-correlation, and variance for
this traffic, for various aggregation levels demonstrates these properties.

The statistics of random sum is studied and used to evaluate performance metrics
in wireless networks. Pertinent wireless network performance measures such as call
completion/dropping probabilities and the average number of handovers usually require
the probability distributions of the cell dwell time and call holding time; and are therefore
not easy to evaluate. The proposed performance evaluation technique requires the
moments of the cell dwell time and is given in terms of the Laplace transform function of
the call holding time. Multimedia services that have Weibull and generalized gamma
distributed call holding times are investigated. The proposed approximation method uses
the compound geometric random sum distribution and requires that the geometric
parameter be very small. For applications in which this parameter is not sufficiently
small, a result is derived that improves the accuracy (to order of the geometric parameter)
of the performance measures evaluated.

Voice over Internet Protocol (VoIP) networks is becoming the most popular
telephony system in the world. However, studies of the security of VoIP networks are
still in their infancy. VoIP devices and networks are commonly attacked, and it is
therefore necessary to analyze the threats against the converged network and the
techniques that exist today to stop or mitigate these attacks. We also need to
understand what evidence can be obtained from the VoIP system after an attack has
occurred.
Many of these attacks occur in similar ways in different contexts or environments.
Generic solutions to these issues can be expressed as patterns. A pattern can be used
to guide the design or simulation of VoIP systems as an abstract solution to a problem
in this environment. Patterns have shown their value in developing good quality
software and we expect that their application to VoIP will also prove valuable to build
secure systems.
This dissertation presents a variety of patterns (architectural, attack, forensic and
security patterns). These patterns will help forensic analysts as well, as secure systems
developers because they provide a systematic approach to structure the required
information and help understand system weaknesses. The patterns will also allow us
to specify, analyze and implement network security investigations for different
architectures. The pattern system uses object-oriented modeling (Unified Modeling
Language) as a way to formalize the information and dynamics of attacks and
systems.

We developed a cross layer design which combines retransmission diversity and
multi-user diversity for wireless communication. To this end, a joint design of
adaptive modulation and coding with retransmission-based automatic repeat request
protocol is outlined. This design is applied to devise multi-user scheduling schemes,
which can optimally capture the available multi-user and retransmission diversities. In
addition, the proposed on-line scheduling algorithms can operate even when the
underl ying fading channel distribution is unknown, while asymptotically converging
to the offline benchmark with guarantees on prescribed fairness and rate requirements.
Numerical results are provided to verify the merits of our novel schemes for
multi-user transmissions over Nakagami block fading channels.

A novel personnel authentication and verification system for devices
communicating through Bluetooth protocol has been proposed in this thesis.
Unlike existing verification systems which provide password or a PIN as a key,
the system uses biometrics features as a key. In the implementation of the scheme,
ridges and bifurcation based parameters are derived to generate a 128 bit
Bluetooth pairing PIN. In this thesis a unique translational and rotational invariant
feature set has been developed. These extracted feature data, unlike traditional
systems which include the extracted data into payload, is used for device
connection by generating the 128 bit PIN. The system performance is analyzed
using the pairing PIN for inter-sample and intra-sample recognition. To validate
the stability of the system the performance is analyzed with external samples
which are not a part of the internal database.

Wireless sensor networks or WSNs continually become more common in todays world. They
are able to give us a constant view into the world as they gather information and make this information
more readily available. The infonnation these networks gather and contain is valuable and protecting
it is of great importance. Today more and more devices are becoming wireless and mobile. This
is allowing for very diverse networks to be created and they are constantly changing. Nodes in
these networks are either moving to different positions or going offi ine which constantly changes the
overall layout of the network. With this increasing connectivity of today's devices this opens the
door for possibility for these types of networks to become targets by malicious objects designed to
bring harm to the network. Many unre liable networks already face many problems such as having
to optimize battety life and being deployed in areas where they can be damaged. A malicious object
in this type of network has the power to destroy data and deplete the networks limited resources
such as bandwidth and power. Removal of these malicious objects can also have a negative effect
on these limited resources. We must find a way to remove these malicious objects in a way that
minimizes loss to the network. In this paper we will look at the information survival threshold of these types of networks. Certain controllable parameters exist that directly impact the survival rate
of all data in the network. We will combine this with the addition our own self-replicating objects to
the network designed to neutralize their malicious counterparts. We will examine these information
survival threshold parameters along with specific parameters available to the network. We shall see
how these parameters affect overall survival of data in the network and their impact on our own good
data.

Even though, the current cellular network provides the user with a wide array of
services, for a typical user voice communication is still the primary usage. It has become
increasingly important for a cellular network provider to provide the customers with the
clearest possible end-to-end speech during a call. However, this perceptually motivated
QoS is hard to measure. While the main goal of this research has been on the modeling of
the perceptual audio quality, this thesis focuses on the discovery of procedures for
collecting audio and diagnostic data, the evaluation of the captured audio, and the
mapping and visualization of the diagnostic and audio related data. The correct
application of these modified procedures should increase the productivity of the drive test
team as well as provides a platform for the accurate assessment of the data collected.

This research addresses the need for increased interoperability between the varied access control systems in use today, and for a secure means of providing access to remote physical devices over untrusted networks. The Universal Physical Access Control System (UPACS) is an encryption-enabled security protocol that provides a standard customizable device control mechanism that can be used to control the behavior of a wide variety of physical devices, and provide users the ability to securely access those physical devices over untrusted networks.