  Wireless Sensor Networks (WSNs) are highly distributed networks consisting of
a large number of tiny, low-cost, light-weight wireless nodes deployed to
monitor an environment or a system. Each node in a WSN consists of three
subsystems: the sensor subsystem which senses the environment, the processing
subsystem which performs local computations on the sensed data, and the
communication subsystem which is responsible for message exchange with
neighboring sensor nodes. While an individual sensor node has limited sensing
region, processing power, and energy, networking a large number of sensor nodes
give rise to a robust, reliable, and accurate sensor network covering a wide
region. Thus, routing in WSNs is a very important issue. This paper presents a
query-based routing protocol for a WSN that provides different levels of
Quality of Service (QoS): energy-efficiency, reliability, low latency and
fault-tolerance-under different application scenarios. The algorithm has low
computational complexity but can dynamically guarantee different QoS support
depending on the requirement of the applications. The novelty of the proposed
algorithm is its ability to provide multiple QoS support without
reconfiguration and redeployment of the sensor nodes. The algorithm is
implemented in network simulator ns-2 and its performance has been evaluated.
The results show that the algorithm is more efficient than some of the
currently existing routing algorithms for WSNs.
