earticle

영어

In this study, we introduce a new media access control (MAC) protocol that adaptively changes time division multiple access (TDMA) frame size and slot duration in order to upgrade performance of underwater sensor networks. Throughput of underwater sensor networks is very low compared to a radio frequency (RF) network; the reason is a very long propagation delay and a very low bit rate. To solve these problems, we modified the TDMA protocol and introduce a new TDMA MAC protocol (aTDMA). Basically, the TDMA MAC protocol provides a time slot to each node, and the node transmits data in the allocated time slot so transmission does not collide with another node’s transmission. But if a node has no data, it wastes its slot. For the propagation delay in underwater acoustic sensor networks, the length of each slot is very long, so the waste of a slot can cause a serious reduction in performance. The proposed protocol, aTDMA, can remove the wasting of slot times and can change slot duration according to the distance between nodes. Through experiments, aTDMA shows better performance than the conventional TDMA MAC protocol.