Partial messages ordering by double confirmation in wireless sensor and actuator networks

Message ordering is an important issue in wireless sensor and actuator networks, since actuators may take error decisions or actions based on the fail messages ordering from sensors. However, it is difficult to ensure that there is no prior message transmitted in the network, whereas later messages arrived at the actuators. An ordering by confirmation (OBC) algorithm was proposed to address this issue. Nevertheless, the OBC algorithm could not guarantee the rate of correct messages ordering up to 100%. To solve this problem, an ordering by double confirmation (OBDC) algorithm was proposed to guarantee the rate of correct messages ordering up to 100%. However, the OBDC algorithm needs to use more time than the OBC algorithm. Moreover, both the OBC and OBDC algorithms do not address the partial messages ordering issue, since some messages are not co-related to themselves. Therefore the authors propose a partial messages ODBC (POBDC) algorithm to guarantee the rate of correct messages ordering up to 100% with less time. Messages in the POBDC algorithm are divided into independent and partial messages. The simulation results showed that the POBDC algorithm guarantees that the rate of correct messages ordering is 100% and spends less time than the OBDC algorithm.