On the capacity of opportunistic cooperative networks under adaptive transmission

This paper offers a study on Rayleigh channel capacity of opportunistic cooperative networks in conjunction with adaptive transmission where the source adapts its rate and/or power level according to the changing channel conditions while the best relay simply amplifies and forwards the signals. To this end, the upper and lower bound of the end-to-end effective signal-to-noise ratio (SNR) for an arbitrary number of cooperative relays equipped amplify-and-forward protocol is derived and then used to derive the closed-form expressions of the system channel capacity under three different adaptive policies: optimal simultaneous power and rate adaptation (OPRA), constant power with optimal rate adaptation (OPA) and channel inversion with fixed rate (TIFR). Our results are verified through comparison with Monte Carlo simulations where we also illustrate that, among them, for an arbitrary number of relays, TIFR gives the worst channel capacity; OPRA gives the best channel capacity and ORA has a channel capacity quality in between the others.