TABLE OF CONTENTS An ad hoc wireless network is a collection of wireless mobile nodes that self-configure to form a network without the aid of any established infrastructure, as shown in Figure 2.15. Without an inherent infrastructure, the mobiles handle the necessary control and networking tasks by themselves, generally through the use of distributed control algorithms. Multi-hop routing, whereby intermediate nodes relay packets towards their final destination, is often used since it can improve the throughput and power efficiency of the network. Note that with sufficient transmit power any node in the network can transmit a signal directly to any other node. However, such transmissions over long distances will result in a low received power, and will also cause interference to other links. Thus, links with low signal-to-interference-plus-noise (SINR) power ratios are typically not used. The SINR on different links is illustrated by the different line widths in Figure 2.15.
The fundamental capacity limits of an ad hoc wireless network the set of maximum data rates possible between all nodes is a highly challenging problem in information theory even when the nodes only have a single antenna. For a network of K nodes, each node can communicate with K ?1 other nodes, so the capacity region has dimension K( K ?1). While rate sums across any cut-set of the network are bounded by the corresponding mutual information expressions [25, Theorem 14.10.1], simplifying this formula into a tractable expression for the...
