수중 음향 네트워크를 위한 이동 노드 기반의 TDMA MAC 프로토콜

Abstract

In this paper a new medium access control (MAC) protocol, referred to as a Mobile nodes based Time Division Multiple Access (MTDMA), is proposed for underwater acoustic networks (UANets). Particularly, the BTB-TDMA is targeted for managing medium access of multiple mobile underwater nodes (UNs) like underwater vehicles. For this purpose, the MTDMA periodically provides UNs with transmission schedules by using their estimated propagation delays (EPDs). The EPD of a UN is determined by estimating UN's position based upon a previously determined position by measuring linear and angular velocities of the UN. A master node (MN) calculates UNs’ EPDs and sequences UNs’ time schedules as a decreasing order of EPDs. Also, the assigned transmission schedule is time bounded in the unit of block (i.e., the number of time slots) in order to reduce delay of data transfer as well as avoid collision; a UN can transmit data packets without collision if it finishes data transfer within given blocks. This enables the MTDMA to shorten the length of one time slot compared with a classical TDMA whose length of that is equivalent to maximum propagation delay of a UN. Hence, the MTDMA enables to enhance overall delay performance with substantially considering UNs’ mobility.