Wireless sensor networks (WSN) have become one of the most attractive research areas in many scientific fields for the last years. WSN consists of several sensor nodes that collect data in inaccessible areas and send them to the base station (BS) or sink. At the same time sensor networks have some special characteristics compared to traditional networks, which make it hard to deal with such kind of networks. The architecture of protocol stack used by the base station and sensor nodes, integrates power and routing awareness (i.e., energy-aware routing), integrates data with networking protocols (i.e., data aggregation), communicates power efficiently through the wireless medium, and promotes cooperative efforts of sensor nodes (i.e., task management plane).
TopIntroduction
Wireless sensor networks (WSN) have become one of the most attractive research areas in many scientific fields for the last years. WSN consists of several sensor nodes that collect data in inaccessible areas and send them to the base station (BS) or sink (Akyildiz, Su, Sankarasubramaniam, & Cayirci, 2002a). At the same time sensor networks have some special characteristics compared to traditional networks, which make it hard to deal with such kind of networks.
The architecture of protocol stack used by the base station and sensor nodes (Akyildiz, Su, Sankarasubramaniam, & Cayirci, 2002b), integrates power and routing awareness (i.e., energy-aware routing), integrates data with networking protocols (i.e., data aggregation), communicates power efficiently through the wireless medium, and promotes cooperative efforts of sensor nodes (i.e., task management plane). The sensor network protocol stack is much like the traditional protocol stack (Maraiya, Kant, & Gupta, 2011), with the following layers: physical layer, data link layer, network layer, transport layer, application layer, power management plane, mobility management plane, and task management plane.
WSNs have various applications; examples include military applications, environmental monitoring, medical application, home application, industrial and commercial application.
WSNs are deployed in physical harsh and hostile environments where nodes are always exposed to physical security risks damages (Alrajeh, Khan, & Shams, 2013). In WSNs, one of the most important constraints is the low power consumption requirement. Sensor nodes carry limited, generally irreplaceable, power sources. Therefore, they must have inbuilt trade-off mechanisms that give the end user the option of prolonging network lifetime at the cost of lower throughput or higher transmission delay (Akyildiz, Su, Sankarasubramaniam, & Cayirci, 2002a). In order to acquire energy efficiency, various hierarchical or cluster-based routing methods, originally proposed in wire networks, are well-known techniques with special advantages related to scalability and efficient communication.
In a hierarchical architecture, higher energy nodes can be used to process and send the information, while low-energy nodes can be used to perform the sensing in the proximity of the target. The creation of clusters and assigning special tasks to cluster heads can greatly contribute to overall system scalability, lifetime, and energy efficiency. The main aim of hierarchical routing is to efficiently maintain the energy consumption of sensor nodes by involving them in multi-hop communication. Cluster formation is typically based on the energy reserve of sensors and sensor’s proximity to the cluster head. Several cluster-based routing protocols are proposed in the literature such as LEACH (Heinzelman, Chandrakasan, & Balakrishnan, 2002), TEEN (Lee, Noh, & Kim, 2013), APTEEN (Manjeshwar & Agrawal, 2002), HEED (Younis & Fahmy, 2004), PEGASIS (Lindsey, & Raghavendra, 2002) and HEEP (Boubiche, & Bilami, 2011). Where LEACH is one of the first hierarchical routing approaches for sensors networks.