Device-to-Device assisted downlink broadcast channel in cellular networks

In this paper, a Device-to-Device (D2D) communication protocol is proposed to assist multi-input multi-output (MIMO) downlink broadcast channel in the cellular networks. Devices in the D2D group are arranged to decode their data in a well-scheduled hopping sequence. The proposed scheme can fully exploit distributed diversity by selecting the optimal routing of D2D transmissions according to channel conditions. Besides, at each forwarding stage in the D2D group, proper interference cancellation is performed based on previously decoded data stream send from active user, thus the spatial diversity observed by the receiving user is increased at each hop. We derive their outage probabilities in closed forms and show that proposed ordered forwarding protocol provides promising diversity gain and hence avoids the effect of error propagations.