Exploiting macrodiversity in dense multihop networks and relay channels

Embedded networks of sensors and actuators must operate at extremely low power and use inexpensive single-antenna transceivers. The economics of such systems preclude the use of complex signal processing or antenna arrays at any one device. However, the same economics allows the coverage area to be blanketed with a high density of devices, which results in a rich spatial diversity. This spatial diversity can be exploited by forming a virtual antenna array, which combines observations made at multiple receivers. This paper illustrates the potential transmit energy savings that are possible by using such macrodiversity-combining approaches by the analysis and simulation of an idealized system. It concludes by discussing practical issues that must be considered before integrating macrodiversity-combining strategies into actual embedded networks.