Performance Analysis of Multi-Hop Routing Protocol With Optimized Grid-Based Clustering for Wireless Sensor Network

Architecture of a Sensor Node

SNs have four basic components: a sensing unit, a processing unit, a transceiver unit and a power unit. Location finding system, a power generator and a mobilizer are its additional components that are application dependent (Akyildiz et al. 2002).

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  Sensing Unit: Sensing unit usually has two sub-units: Sensors and Analog to Digital Converters (ADCs). Analog signals are obtained by the sensors which are then converted to digital signals by ADC and then given to the processing unit.

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  Processing Unit: It also has two sub-units: processor and storage unit. It manages the procedures needed for collaboration of SNs with each other to perform required sensing operations.

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  Transceiver: It is responsible for connecting the SN with each other and to the other parts of the network.

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  Power Unit: Power unit supplies the energy required by all the board components. The power unit determines the lifetime of the entire network. Energy efficiency is the primary challenge since the battery of the SNs cannot be easily re-charged after the deployment of the SNs.

Other application dependent components of an SN are:

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  Location Finding System: Position finding system like Global Positioning System (GPS) device helps the nodes to locate other nodes. It is useful in obtaining the location accurately as is required by various routing techniques in sensor networks.

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  Mobilizer: It is providing mobility to SNs for completing the assigned task.

Protocol Stack Architecture

In WSN, the protocol stack is made up of the application layer, transport layer, network layer, data link layer, physical layer, power management plane, mobility management plane and task management plane. The responsibilities of physical layer include transmitting and receiving a signal over a physical medium. It determines various characteristics like frequency of operation, modulation technique, data encryption, etc. The main functions of data link layer are multiplexing of the data stream, transmission and reception of data frame, medium access and error check. The network layer is concerned with routing. It routes the data from source to destination which is managed by the transport layer. This layer maintains the data flow when required by the application layer. Application layer is required when the system is to be accessed via internet or other external network. Application layer develops several application softwares depending upon the sensing task requirement. Also, the power, mobility and task management planes make SNs work collectively, route data, share resources and distribute task among them so as to make use of power efficiently. The power management plane optimizes the power usage by the SN. The mobility management plane tracks the SN's movement to maintain a returning route to the user, and also find out neighbors of the SNs. For balancing the load, task management plane distributes the sensing duties among several SNs.