Collaborative Research: Cognitive Ad Hoc Networks: Capacity Optimization Through Local Adaptation

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

Title: Collaborative Research: Cognitive Ad Hoc Networks: Capacity Optimization Through Local Adaptation 0635003, Weber 0634979, Andrews 0634763, Jindal Due to the unpredictability of the environment in which unplanned (ad hoc) wireless networks will operate, an appealing approach is to allow the network to dynamically adapt to the perceived conditions. We define such ad hoc networks as cognitive. A framework is developed for understanding the benefits of local adaptation, by breaking adaptive techniques into the four major degrees of freedom available to the designer: time, frequency, code, and space. The aim is to address the following two questions. First, what are the fundamental limits on information flow through unplanned networks; in particular, how valuable is localized information and coordination in seeking to achieve this limit? Second, what are the relative values of adaptation in time, space, frequency, and code in terms of information flow; in particular, how does the network designer identify which degree of freedom is most valuable in a variety of networking scenarios? In this research, information theory and stochastic geometry are connected through a novel metric for ad hoc network capacity, termed the transmission capacity. This metric captures the maximum spatial intensity of transmissions subject to a specified outage probability. While related to other popular capacity metrics, notably the transport capacity, the transmission capacity is unique in its allowance of explicit and accurate characterization of capacity for any conceivable communication scheme or transmission environment. The transmission capacity is an indispensable unifying metric for this analysis since i) it allows closed-form results, ii) does not require any global coordination or optimization, iii) accurately models the interference environment of an ad hoc network. These innovations will allow a basis for more efficient wireless network design.