Wireless Network Design: Optimization Models and Solution ...

1 Introduction to Optimization in Wireless Networks 5
protocols have been proposed that are solutions to optimization problems with different
objective functions and constraints. For instance, a routing protocol might be
optimized to minimize the overall energy consumption in the network. Chapter 9
discusses in detail the routing and the associated quality of service provisioning
problems in MANETs.
Chapter 10 considers power optimization for a specific problem in ad-hoc networks.
This chapter considers a broadcast/multicast scenario in which one transmit
node desires to send its data to a collection of nodes. Several compact integer programs
to solve problems of this flavor are addressed in Chapter 10. As noted before,
in a MANET, node mobility can pose a significant challenge in ensuring a fully connected
network at all times. Chapter 11 addresses the issue of maintaining network
connectivity under mobility conditions. The main idea in Chapter 11 is the use of
designated mobile nodes (called agents) which predict the movement of the other
nodes (based on prior observations) and select their own path to ensure that the network
remains fully connected. A particle swarm optimization is proposed to select
the positions for the mobile agents at each time interval.
With the growth in the size and complexity of the networks, analyzing their performance
is a challenging task. Fortunately, the advances in semiconductor technology
have made computing power and memory inexpensive and widely available.
Simultaneous to this growth, novel tools and techniques for simulating networks
have also been developed. Chapter 12 provides an overview of the major techniques
used to design networks and analyze their performance using simulation methods.
WiMAXWorldwide Interoperability for Microwave Access has emerged as a serious
contender for providing ubiquitous broadband services in both fixed wireless
and mobile settings over a broad service area. Chapter 13 is focused on operational
time optimization procedures used to improve the performance of WiMAX networks.
These WiMAX networks are based on the OFDM concept and this chapter
explores the optimization issues that arise specifically in that setting. The focus
of the chapter is on optimizing the radio resource allocation and multiuser packet
scheduling within the OFDM framework.
One of the challenges of communicating over the wireless channel is the time
varying nature of the channel. These time variations pose a serious challenge in
ensuring that the desired quality of service is maintained without interruption. Simultaneously,
the system must leverage these variations to improve the long term
performance of the system. Channel aware scheduling has emerged as a key concept
in achieving superior performance over a wireless channel. Chapter 14 provides a
comprehensive overview of the main scheduling methods and their performance.
The scheduling problem becomes even more relevant in a multiuser setting where
the channels of the different users vary independently of each other. The scheduling
framework should strike a balance between optimizing network performance (such
as throughput) with the requirement for ensuring fair allocation of resources to the
various users. Chapter 14 discusses several fairness metrics and how they can be
incorporated as constraints in the scheduler optimization framework. Finally, we
conclude this book with Chapter 15, which looks at the major trends in the field of