A Distributed Multi-Channel Feedbackless MAC Protocol for D2D Broadcast Communications In Device-to-Device (D2D) broadcast communications, the design of Medium Access Control (MAC)protocol is quite challenging since it is urged on alleviating data collision under the constraints of no feedback messages, no central coordination, and half-duplex transmission. We propose a multi-channel MAC protocol for data channel competition. Theoretical and simulation results show that this protocolresolves all channel collisions in only a few iterations. Moreover, the collision resolution time is dominated by the number of channels, rather than the number of D2D transmitters. Thus, even in scenarios with densely-distributed D2D devices, the proposed protocol can guarantee short collision resolution time.