分层M2M网络中分簇节点MAC优化研究

The optimization of MAC in hierarchical M2M networks with cluster head

在高密度节点分布的分层结构M2M(Machine-to-Machine)网络中,同层簇头间和终端节点一般采用随机机制竞争信道,簇头或终端节点竞争信道机会相近,特别是簇头数据量较大就可能存在延时较大或丢包.为了减小簇头的延时和丢包率,提出了一种BT-MAC算法,在终端节点和簇头间竞争信道时,根据节点需发送数据量反比设定节点退避时间,因此簇头传输的数据量越大,算法设定的平均退避时间就越小,相当于簇头发送的优先级越高,从而减少碰撞,提高簇头接入信道的概率.仿真结果表明,对比常见的DMAC协议和SMAC协议,BT-MAC算法能提高簇头接入信道概率达到较小的平均延迟,同时也能减少节点的平均能量消耗.

In hierarchical M2M（Machine-to-Machine）networks with high-density of nodes, the interlayer cluster heads and terminal nodes generally adopt the random mechanism to compete channel, so cluster head or terminal nodes contend for the channel with similar opportunity, especially the cluster head has large amount of data to transmit, which may cause high delay or packet loss. In order to reduce delay and packet loss rate of cluster heads,then presents BT-MAC（（Based on Traffic Medium Access Control） algorithm, when terminal nodes and cluster head compete channel, based on the amount of data to be sent algorithm with inverse proportion to set backoff time of the node. So the greater data cluster head transfer, the smaller average backoff time is, equivalent to set cluster head a higher priority, thereby collisions reduce, and the probability of cluster head increase. Simulation results show that BT MAC algorithm can improve the channel access probability of cluster head thereby to achieve a smaller average delay and can reduce the average energy consumption of nodes, compared to the common DMAC proto- col and SMAC protocol.