Flipped Diversity Aloha in Wireless Networks with Long and Varying Delay

The design of random media access control (MAC) renews great attention for emerging challenged wireless environments where the propagation delay is long and varying, such as satellite or underwater acoustic sensor networks. In these environments, the existing MAC solutions based on slotted transmissions, carrier sensing, or channel reservation by control packets are no longer favorable or even feasible. In this paper, we propose the Flipped Diversity Aloha (FDA) MAC protocol to tackle the challenges based on a new diversity transmission scheme. Different from the existing diversity transmission schemes, each data packet and its flipped version are transmitted back-to-back, and the receiver uses the Zigzag decoding technique to decode collided packets. The performance of FDA has been evaluated by analysis and simulation. The results show that, without time synchronization or handshaking requirements, the performance of FDA is unaffected by the duration or variation of the propagation delay, and it can substantially improve system performance in terms of throughput, packet loss ratio, and network admission region.