In a span of less than thirty years, cell phones have become ubiquitous and wireless data access
has become one of the most common methods of communication today. Due to its wide-spread
popularity, wireless networks have also evolved in terms of higher bandwidth and lower end-toend delay to support delay sensitive applications such as voice and video. For example, 1G and
2G networks that were deployed in late eighties and early nineties could only support data rates
up to a few tens of kbps traffic and voice communication but by the start of the new millennium,
they evolved into 3G networks supporting up to 2 mbps data rate. Currently, 4G networks (e.g.,
LTE, WiMAX) are being deployed that support multimedia communication and provide data
transfer rates up to 100 mbps while supporting 50 ms end-to-end delay. As these networks have
been evolving there has also been an exponential growth in the use of mobile devices and
bandwidth intensive killer applications.
In order to support communication among these myriad types of mobile devices and delay
sensitive applications it is now a challenge for the mobile operators to design scalable and
optimized networks that can provide the desired quality of service to mobile end users.
Heterogeneity of access technologies (e.g.,LTE, WiFi, WiMAX) and roaming is needed across
service provider domains. This need for ubiquitous access requires service providers to deploy
efficient protocols and design scalable mobile networks that can provide secure and seamless
mobility. Similarly, the architects and network designers of the enterprise networks strive to
provide secured and seamless roaming access to users as they access services through external
networks over the VPN. In order to support seamless mobility in adhoc and M2M type networks
such as military networks and vehicular networks, the infrastructure should be equipped with
appropriate mobility protocols that support node movement such as simultaneous mobility. As
streaming, conferencing, and multimedia applications become more prevalent among mobile
users, the careful design and implementation of protocols is needed to support the stringent
delay and performance requirements of these applications. While network designers, systems
architects, and application service providers are faced with the challenges of selecting the right
type of protocols to provide the desired quality of service for the mobile users, they also have to
optimize available resources, such as capacity in core networks, and spectrum usage in the radio
access network. Hence, while deploying these mobile networks, care must be taken to study the
tradeoff between available resources and desired quality of service. In order to come up with an
optimal network design that balances resource constraints with quality of service in the mobile
networks, a model-based approach is found to be useful.
With the advent of various kinds of wireless networks such as potential wide-scale deployment
of 4G networks, service providers are faced with the choice of deploying the right set of mobility
protocols that are available at various layers. However, it is essential to develop optimization
techniques in a systematic way that evaluate the applicability and performance of any mobility
protocol before it actually gets deployed. These optimization techniques will need to take
into account various components of a mobility event such as security, configuration,
authentication, quality of service, and mobile's movement environment. Having a common
framework and an abstract model that can analyze the mobility components and derive the
systems optimization techniques will make it easier to choose or design the right set of protocols
that can provide an optimized mobility management scheme specific to a mobility use case.
Thus, there is a dire need for a handbook that addresses best current practices to analyze the
performance of mobility protocols and provide a set of systems optimization techniques for
different mobility deployment scenarios in an easy to understand format. Wireless Internet
Service Providers (WISPs) can benefit from such a handbook that can provide a thorough
analysis of the required steps during a mobility event such as discovery, network selection,
configuration, authentication, security association, encryption, binding update, and media
redirection.
This book introduces the mobility protocols at different layers, provides a systematic analysis of
the mobility event and investigates the optimization techniques associated with each of the
handoff operations at different layers. It takes into account various kinds of mobility deployment
scenarios including wireless service providers, enterprise networks, ad hoc networks, and
vehicular networks supporting both unicast and multicast traffic. This book provides a formal
analysis of the mobility event that is unique and has not been covered until now by any other
book. The framework and abstract model proposed in this book can be used to understand and
analyze the usefulness of various optimization methodologies. This system model can help to
design an optimal mobility network. Results and performance analysis from the mobility testbeds and theoretical models further validate these optimization techniques for various types of
use case scenarios.
Organization of the book:
This book is organized as follows. Chapter 1 introduces the main theme of the book,
underscores the importance of systems optimization in mobility management and highlights the
key technical contributions of each of the subsequent chapters. Chapter 2 introduces mobility
management in cellular and IP-based networks and discusses the related mobility protocols that
are currently available. We provide a systematic analysis of the mobility event and associated
handoff components in Chapter 3. In Chapter 4, we introduce a formal systems model that uses
Petri nets to analyze the behavioral properties of a mobility event and the associated optimization
techniques. Chapter 5 discusses optimization techniques for layer 2 handoff in 802.11
environment. Chapter 6 describes some key mobility optimization techniques for IP-based
mobility protocols that we have developed for different components of the handoff event and
demonstrates their validation through actual experiments. Chapter 7 discusses optimization
techniques associated with multi-layer mobility protocols. Chapter 8 introduces simultaneous
mobility, analyzes the probability of its occurrence and proposes respective optimization
techniques for layer 3 and application layer mobility protocols. Chapter 9 describes optimization
techniques for multicast stream delivery in a hierarchically scope-based multicast architecture.
Chapter 10 highlights mobility optimization by way of cooperative roaming. Chapter 11
evaluates a few handoff systems that we have prototyped using some of the optimization
techniques by way of experiments and Petri net models, investigates the behavioral aspects of the
handoff operations such as deadlocks and analyzes the trade-off between different schedules for
handoff and the systems resources. Chapter 12 concludes with a discussion on best current
practices of mobility optimization, a summary of contributions, and some possible future
research directions.
We include three appendices after the bibliography section. In Appendix A, we define the RDF
schema for application layer discovery. In Appendix B, as part of the glossary, we define an
alphabetical list of the abbreviations that are used. In Appendix C, we define many of the
mobility related terms.
Intended audience:
In particular, the networking professionals in the following field will benefit from this book in
their respective areas.
Architect for wireless service providers: Many of the wireless service providers are building LTE
networks based on 3GPP specifications. These systems generally suffer from optimization
problems during handover and roaming. Systems Architects who design the LTE networks will
learn about the methods available for optimizing different handoff functions in a heterogeneous
access network. Architects are responsible for designing the complete system where mobility and
security protocols interact. It is very important to understand their inter-dependency. This book
provides an overview of how mobility optimization is affected by other protocols related to
security, configuration, and authentication.
Researchers: This book covers both the theoretical and practical aspects of mobility optimization
and addresses some of the associated research issues including modeling and cross-layer
optimization. Researchers will be able to analyze the results through mobility models and
experiments and further enhance their own research work.
Systems Engineers: Systems Engineers are in charge of integrating different parts of the system
and ensuring that it is ready for operation. Since this book covers many of the experimental
results from live test-beds involving heterogeneous wireless access such as
CDMA, and 802.11, it provides some real insight into the operational aspects of mobility
optimization in a real-world deployment scenario.
Protocol Designers: Since this book covers the basics of mobility management and the associated
optimization techniques, protocol designers will get a chance to learn about the fundamental
principles of optimization. This will help them design new protocols or enhance the existing
protocols suitable for a specific mobility deployment.
IT professionals: IT professionals in enterprise networks are always challenged to design an
optimized enterprise network that can provide the desired quality of services to the end users
under resource constraints. For example, they have to decide whether they need to provide a
layer 2 or layer 3 mobility management to support handoff or whether they need any cross layer
feedback during handoff. This book provides an analysis and comparison between different types
of mobility protocols useful for the efficient deployment of mobility protocols.
Standards professionals: This book provides an overview of many important mobility and
security related protocols developed by the IETF as well as their application in the mobile
networks as defined by 3GPP. The standards contributors will benefit from the fundamental
principles of mobility optimization, methodology, and best current practices described in the
book. This will help them to design new mobility optimized protocols.
CTOs: Chief Technology Officers of wireless service providers will get a bird’s eye view of
mobility management and optimization techniques that can be applied to different deployment
scenarios. Since these techniques take into account other operational aspects such as security and
quality of service, as well as roaming, they can use this book as a reference book when they
interact with other groups within the organization such as CSO, network planning, network
deployment and study their inter dependencies.