  Wireless sensor/actuator networks (WSANs) are emerging rapidly as a new
generation of sensor networks. Despite intensive research in wireless sensor
networks (WSNs), limited work has been found in the open literature in the
field of WSANs. In particular, quality-of-service (QoS) management in WSANs
remains an important issue yet to be investigated. As an attempt in this
direction, this paper develops a fuzzy logic control based QoS management
(FLC-QM) scheme for WSANs with constrained resources and in dynamic and
unpredictable environments. Taking advantage of the feedback control
technology, this scheme deals with the impact of unpredictable changes in
traffic load on the QoS of WSANs. It utilizes a fuzzy logic controller inside
each source sensor node to adapt sampling period to the deadline miss ratio
associated with data transmission from the sensor to the actuator. The deadline
miss ratio is maintained at a pre-determined desired level so that the required
QoS can be achieved. The FLC-QM has the advantages of generality, scalability,
and simplicity. Simulation results show that the FLC-QM can provide WSANs with
QoS support.
