介质访问控制(MAC)协议是水声通信网络中的关键技术,由于水声信道的可用带宽有限、多径效应严重、长延迟等特性,使得水声通信网络中的MAC设计存在诸多难题.无线通信网络中的MAC协议设计通常没有考虑延迟效应,而采用这种方法来设计水声通信网络的MAC协议,其性能将大大降低.为了克服上述问题,基于MAC协议中的海底采集多路访问(FAMA)协议,提出了适用于水声通信网络的时隙FAMA一清除发送(CTS)协议,该协议为CTS包分配了单独的时隙.同时,还提出了一种能量优化方法来传输数据.该算法不仅能够增加水声通信网络的吞吐量,减少数据包的碰撞而且能够降低能量消耗,并且该算法能够有效的将载波侦听与发射和接收数据前的协商结合在一起.实验结果表明,与时隙碰撞避免多址接人(MACA)协议和FAMA一非持久请求发送(FAMA-NTR)协议相比,本文提出的算法更有效.
Medium access control(MAC)protocol is a key technology for underwater acoustic communication network(UACN). Due to the underwater acoustic channel's low available bandwidth, highly varying multipath, high propagation delay characteristics,it is difficult to design an efficient MAC protocol. Most of the MAC protocols for wireless terrestrial communication networks have been designed with negligible propagation delay in mind, if it is deployed directly in an underwater environment, the UACN will perform inefficiently. To overcome the above problem,a new MAC protocol suitable for UACN is proposed and analyzed in this paper. We propose some modifications in floor acquisition multiple access(FAMA)of MAC protocol for UACN in which we use a time slot, which is applied for Clear-To-Send(CTS)packet, thus called Slotted FAMA CTS. An energy optimization strategy for data transmission is also proposed in this paper. The goals of this work are to increase throughput rate, decrease packet collisions due to propagation delay of hidden nodes and to provide savings in energy. This protocol combines both carrier sensing and a dialogue between the sender and receiver prior to data transmission. Simulation results show that the proposed method is more effective than Slotted Medium Access Control Avoidance(MACA)and FAMA-non persistent transmit request(FAMA-NTR)protocol.