Cellular-Aided Device-to-Device Communication: The Benefit of Physical Layer Network Coding

We introduce a cellular-aided device-to-device (D2D) communication model in which two D2D transmitters (Txs) send independent messages W₁ and W₂ to their intended D2D receivers (Rxs) with the help of a base station (BS). Specifically, at the first phase, two Txs send their signals to both the BS and two Rxs and then at the second phase the BS sends its signal to the Rxs. We consider a feasible channel assumption that D2D channels are not always available at the BS and each Tx, thus resulting in an outage. For the proposed cellular-aided D2D scheme, the Txs send their messages via physical layer network coding, and thus, the BS is able to decode W₁⊕ W₂ and broadcasts it to the Rxs. In consequence, from the fact that an outage does not occur if each Rx can decode W₁ or W₂ from its D2D links, the outage probability is significantly reduced compared with the D2D only communication where each Rx needs to decode its own message.