The Sum-Rate Capacity of a Cognitive Multiple Access Sensor Network

Abstract

This paper investigates the sum-rate capacity of a cognitive multiple access (MAC) sensor network. The multiple access network consists of K sensors communicating to a common base station. Outside of the network exists another user of the radio spectrum. Each sensor of the MAC network is aware (i.e. cognitive) of this user, denoted the primary user, and transmits in a manner to avoid any interference to this user. No interference transmission is achieved using the dirty-paper coding technique. The sum-rate capacity is the theoretical maximum of the sum of the simultaneously achievable rates of each sensor within the network. Using a recently derived iterative algorithm, we quantify the sum-rate capacity of this network and investigate its behavior as a function of the number of sensors, cognitive signal-to-noise ratio (CSNR) and primary SNR (PSNR) in a Rayleigh fading environment. We also derive bounds and scaling results for the ergodic sum-rate capacity.