Energy Minimization in Wireless Sensor Networks Using Multi Hop Transmission
IOSR Journal of Computer Engineering
Wireless technology has enormous potential to change the way people and things communicate. Wireless cellular networks allow people on the move to communicate with anyone or anything using a range of multimedia services. Of all potential wireless applications, sensor networks are special due to their emphasis on communication between devices. In addition, these networks have hard energy constraints since each node is powered by a small battery that may not be rechargeable or renewable.
... renewable. Therefore, reducing energy consumption is the most important design consideration for such networks. A sensor network is composed of dozens, or even thousands of nodes, connected in a systematic way, as shown in Fig. 1 .1. This figure indicates that the information from the sensors flows into a hub node. As shown in the figure, if the source node is far away from the hub node, intermediate nodes can help with relaying via multihop transmissions. These networked sensors are distributed to collect information on entities of interest. A wireless sensor network (WSN) consists of a group of self-organizing, lightweight sensor nodes that are used to cooperatively monitor physical or environmental conditions. Commonly monitored parameters include temperature, sound, humidity, vibration, pressure and motion . Each sensor node in a WSN is equipped with a radio transmitter, several sensors, a battery unit and a microcontroller. Although the WSN research was initially motivated by military applications, wireless sensor networks are now used in many industrial and public service areas . Sensor nodes are inexpensive portable devices with limited processing power and energy resources. The Sensor nodes can be used to collect information from the environment, locally process this data and transmit the sensed data back to the user. Sensor nodes consist of five main components : a computing unit, a communication unit, a sensing unit, a memory unit, and a power supply unit. The computing unit consists of a microprocessor. The microprocessor is responsible for managing the communication protocols, processing collected data from the on-board sensors, and performing the power management. Each sensor node has a single communication unit that is able to transmit and receive packets. This unit combines the functionality of both transmitter and receiver . Although all sensing, computing and communication operations consume energy, data communication requires more energy than sensing and computing. Thus, reducing data communication between sensor nodes can improve the energy efficiency and extend the lifetime of sensor networks. A WSN is able to self-configure its operation and manage its connectivity. A WSN is also able to tolerate malfunctioning nodes and integrate new nodes in the network since node failure is common in WSN applications . Because of the limited power and transmission range in a large sensor network, the communication between sensor nodes must be multihop. Data from a source sensor node relayed by a number of intermediate nodes before it reaches the final destination. The Collaboration between sensor nodes and in-network processing are necessary in sensor networks since a single node may not have all the data concerning some event of interest .