Is relayed collaborative communication worth it?

We consider a collaborative wireless distributed network, consisting of one source transmitting information to a remote destination in the presence of N relay nodes. We assume that all nodes have similar capabilities, are randomly distributed geographically, immersed in the clutter and close to the ground, each employing a single antenna. Assuming a Decode-and-Forward technique, we propose various collaborative approaches for signaling. Using well-known channel coding techniques, the destination is not able to start decoding its intended message until all nodes have decoded the entire message. Using more sophisticated coding techniques, the destination can start decoding the transmitted message at the start of the communication by the source. Various ways of organizing the relay collaboration are: Generalized Beamforming; Generalized Alamouti; and Simultaneous Casting. We then evaluate the performance of these collaborative approaches by simulations, employing an appropriate fading/path loss channel model. Obtained results will demonstrate the superiority of the sophisticated coding technique used and provide insights on when collaboration in networked multiple antennae systems is useful. Specifically, a gain of the order of 9 dB in the required transmit power is achieved assuming Simultaneous Casting and 0 dB transmit power per node, compared to the case when these sophisticated codes are not used. Finally, we also observe a gain in the system 10^th percentile outage rate on the order of 1.4 bit/s/Hz at a 0 dB transmit power and with Generalized Beamforming, compared to the case where relays are not used.