An experimental framework for the evaluation of cooperative diversity

Cooperative diversity is the result of relaying among nodes to achieve space diversity in multipath environments that offer limited time and frequency diversity. Although there is now substantial literature covering specification and analysis of cooperative communication strategies based upon models of wireless environments, there is much less work addressing experiments with real-world radio hardware and propagation channels. This work describes the construction of a three node, experimental testbed based upon a network of software-defined radios for development and verification of cooperative protocols. Several decode-and-forward relay protocols have been implemented and evaluated in terms of their diversity gains as measured from experimental curves of bit-error rate versus average signal-to-noise ratio. In contrast to the few other implementation efforts reported, the experimental setup maintains the relative node geometry while moving the network to induce fading, and the experimental results exhibit diversity benefits.