Abstract: For delaytolerant mobile sensor networks with highly dynamic and sparse topology, an energyefficient medium access control (MAC) protocol called delaytolerant MAC (DTMAC), used in asynchronous duty cycle, adopted with a transfer mode initiated by the receiver, and minimal active exploration packet with multifunction introduced, is proposed. Via reducing retransmission rate and control packets costs, the energy consumption is efficiently controlled. Experiments on wireless sensor networking platform indicate that DTMAC can achieve energy efficiency, and also improve the performance both in onehop latency and the network throughput.

Key words: delay-tolerant mobile sensor networks, neighbor updating, transfers initiated by a sink, minimal active exploration packet