Virtual Token Passing Protocol Applicable to Manufacturing Sensor Networks

In this paper, a virtual token passing protocol has been proposed, in which sensor nodes join in the different subnets according to the received signal strength and the number of sensor nodes in the subnet to decrease the transmitting power to reduce energy consumption as far as possible. Secondly, router nodes adopt different RF to polling for new sensor node and neighboring subnets use different channels to realize internal communication, and this can not only improve the network capacity, but also reduce the interference between subnets and sensor nodes. Thirdly, the address of sensor nodes in subnet is allocated by the router in a unified way. By making full use of the continuity of address and the negotiation mechanism, sensor nodes impartially access the wireless channel according to the virtual token passing method, and this has greatly reduced the effect on network performance brought by token passing and maintenance. In addition, the introduction of node priority and second competition state make the higher sensor nodes have priority to access wireless channel and then send packet as soon as possible, and this will enhance the real-time performance and reliability further when there is an emergency happened. OPNET simulation experimental results show that the proposed MAC protocol has improved the throughput, increased the traffic load, decreased the network delay, reduced the amount of dropped packets and the wireless channel access delay, and this is of great importance to the wireless sensor network under manufacturing environment.