CSMA is a kind of multi access classification for carrier detection. With adoption of distributed control method,it is a kind of simple and useful channel allocation mechanism,and its conflict avoidance is to detect conflict by monitoring whether the channel is busy or not. The underwater sensor networks,with high-delay,low bit rate,easy fault and so on,is different significantly from the terrestrial wireless networks. Traditional terrestrial wireless MAC protocol cannot be applied into the underwater sensor networks due to its low effi-ciency. Therefore,it is necessary to design an efficient MAC protocol for underwater sensor networks. For this,an NC-CSMA protocol,as an collision-free one applied in underwater sensor networks,is proposed based on the Carrier Sense Multiple Access ( CSMA) . Combined with the characteristics of dual round scheduling and CSMA,each node transmits data frame in a fixed order and it has collision-free and high channel utilization. The simulation on comparison with CSMA protocol shows that the NC-CSMA protocol is efficient.%CSMA是载波检测多路访问分类,采用分布式控制方法,它的冲突避免是通过监听信道是否忙碌判断发生冲突,是一种简单而实用的信道分配机制.由于水下传感器网络与陆地无线网络有着显著的不同,水下传感器网络具有高时延、低比特率、容易出错等特点,而传统陆地无线MAC协议效率低,不能够应用到水下传感网络.这非常有必要去设计一个适用水下传感网络的高效MAC协议.于是通过改进CSMA协议,一种应用到水下传感网络的无碰撞MAC协议,也就是基于载波侦听多路访问协议(CSMA协议),提出一种No Conflict CSMA协议(NC-CSMA协议).该协议结合了双轮转调度机制和CSMA的特点,每个节点传输数据帧都按照固定的顺序,具有无碰撞特点和高信道利用率.在仿真实验中与CSMA协议进行了比较,结果证明了NC-CSMA协议的高效性.
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