Towards an Information Theory of Large Wireless Networks

Thursday, August 9, 2001 - 11:00am - 12:00pm
Keller 3-180
Piyush Gupta (Alcatel-Lucent Technologies Bell Laboratories)
Last few decades have seen widespread deployment of cellular voice and data wireless networks and satellite communication systems. These applications have motivated researchers to extend Shannon's information theory for single-user channel to some involving communication among multiple users; a few such examples are multiple-access channel, broadcast channel, and interference channel. Both the above applications as well as the channels used for analyzing them involve mainly single-hop wireless communication.

More recently, there has been considerable interest in another type of wireless networks, namely, multi-hop or ad hoc wireless networks. These networks consist of a group of nodes that communicate with each other over a wireless channel without any centralized control. Examples are in networking mobile computer users on a campus, Bluetooth, HomeRF, and automated transportation systems.

In this talk, we discuss an information-theoretic framework for analyzing such multi-hop wireless networks. We propose an information-theoretic constructive scheme for obtaining an achievable rate region in such networks. Many well-known capacity-defining achievable rate regions can be derived as special cases of the proposed scheme; a few such examples are: degraded and reversely-degraded relay channels, Gaussian multiple access channel, and Gaussian broadcast channel. Applying the proposed scheme to a specific wireless network of n nodes located in a region of unit area, we show that a transport capacity of (n) bit-meters/sec is feasible, as compared to the best possible transport capacity of (n) bit-meter/sec shown earlier for models based on current technology. An implication is that designing and employing more sophisticated multi-user coding schemes can conceivably provide sizable gains in large wireless networks.

This is joint work with Prof. P. R. Kumar.