Implementation and evaluation of token-scheduled collection protocol in wireless sensor network

TDMA is more suitable for high throughput data collection than CSMA. Yet, in wireless sensor network plain TDMA-based protocols require complex scheduling. In case of node failures, plain TDMA is hard to recover connection and achieve robust data collection due to the complex scheduling burden. Toward robust data collection, it is important to develop a collection protocol capable of topology adaptability. We have been developing a data gathering protocol named TKN-TWN. TKN-TWN exploits the advantages of TDMA and eases the scheduling burden by using two tokens to arbitrate transmission, providing high throughput via burst data transmission. Moreover, due to the simplified scheduling based on tokens, TKN-TWN is practical to provide adaptability for infrequent topology changes. We enhance the implementation of TKN-TWN over the previous work and carry out experiment on a deployed network in the office room to evaluate the throughput and topology adaptability as well. Experimental results in the network consisting of 32 TinyOS enabled sensor nodes show that TKN-TWN is robust to network changes caused by occasional node failures. Evaluation also shows that TKN-TWN is able to even provide throughput over 10 KByte/s.