| dc.description.abstract | How much information can be transferred over a wireless network
and what is the optimal strategy for the operation of such
network? This thesis tries to answer some of these questions from
an information theoretic approach.
A model of wireless network is formulated to capture the main
features of the wireless medium as well as topology of the
network. The performance metrics are throughput and transport
capacity. The throughput is the summation of all reliable
communication rates for all source-destination pairs in the
network. The transport capacity is a sum rate where each rate is
weighted by the distance over which it is transported. Based on
the network model, we study the scaling laws for the performance
measures as the number of users in the network grows.
First, we analyze the performance of multihop wireless network
under different criteria for successful reception of packets at
the receiver. Then, we consider the problem of information
transfer without arbitrary assumptions on the operation of the
network. We observe that there is a dichotomy between the cases of
relatively high signal attenuation and low attenuation. Moreover,
a fundamental relationship between the performance metrics and the
total transmitted power of users is discovered. As a result, the
optimality of multihop is demonstrated for some scenarios in high
attenuation regime, and better strategies than multihop are
proposed for the operation in the low attenuation regime. Then, we
study the performance of a special class of networks, random
networks, where the traffic is uniformly distributed inside the
networks. For this special class, the upperbounds on the
throughput are presented for both low and high attenuation cases.
To achieve the presented upperbounds, a hierarchical cooperation
scheme is analyzed and optimized by choosing the number of
hierarchical stages and the corresponding cluster sizes that
maximize the total throughput. In addition, to apply the
hierarchical cooperation scheme to random networks, a clustering
algorithm is developed, which divides the whole network into
quadrilateral clusters, each with exactly the number of nodes
required. | en |
