Literature Review of MAC, Routing and Cross Layer Design Protocols for WSN

Introduction

Although a WSN is a wireless multi-hop network, it has distinguished features over the traditional multi-hop wireless networks. These features are related to the deployment of sensor nodes, the resources constraint, and the QoS requirement of the WSN. These distinguished features must be considered when designing different protocols that control the operation of WSN such as MAC protocols and routing protocols. Sensor nodes are usually deployed randomly. There is not a predefined infrastructure of the established network. Therefore, sensor nodes must organize themselves autonomously. Self organizing techniques must be integrated within MAC and routing protocols. On the other hand, Existing of many nodes close to each other generates redundancy in the data gathered from the environment. Therefore, it is not required to transmit all the sensed data, data aggregation can be performed at each intermediate sensor node. Data aggregation will reduce the data traffic in the network. The aggregation function depends on the application. Sensor node has limited resources, for example, all the sensor nodes have a limited power supply (batteries). In most WSN applications, all the sensor nodes are out of control, it is impossible to replace or recharge these batteries. All the control protocols of the WSN must be designed taking into account the energy constraint. These protocols must be energy efficient. Another example of limited resources in the sensor node is the radio transceiver. The transmission range for radio transceiver of the sensor node is very limited. Therefore, not all the sensor nodes in WSN can hear all other nodes. All sensor nodes must collaborate to transfer data from the source sensor node to the sink. Different WSN applications needs different QoS requirement. For example, Data latency in WSN is very critical in some applications and not so much in other applications. Taking into account these distinguished features, a lot of MAC, routing and cross layer design protocols for WSN are proposed.

A WSN is composed of a large number of sensor nodes that are communicated using a wireless medium (air) as shown in Figure 1. The sensor nodes are deployed in the environment to be monitored in ad hoc structure. In WSN, there is sink node that collects data from all sensors, and usually not all nodes hear all other nodes. WSN is considered a multi-hop network.

Figure 1.

A wireless sensor network

Although a WSN is a wireless multi-hop network, it has distinguished features over the traditional multi-hop wireless networks. These features are related to the ease of deployment of sensor nodes, the system lifetime, the data latency, and the quality of the network. These features must be taken into account when designing different protocols that control the operation of WSN such as MAC protocols and routing protocols. Therefore, Many MAC and Routing protocols are proposed for WSN. These protocols take into account the distinguished features of WSN. Moreover, Cross layer design protocols are proposed for WSN. In cross layer design protocols, different layers interact to optimize the performance of the WSN protocol.

In this chapter, we will present a survey of the most well known protocols for WSN. In section ‎1.2, we will present the distinguished features of WSN that motivate proposing control protocols dedicated to WSN. A survey of the most well-known MAC protocols is presented in ‎1.3. Section ‎1.4 presents discussion of routing protocols of WSN and classification of these protocols according to data traffic models. The routing protocols are also classified as: data centric protocols, hierarchical protocols, location-based protocols and QoS-aware protocols (Akkaya & Younis, 2005). In section ‎1.5, we will present some cross layer design protocols for WSN. A summary of the cross layer design protocols is presented at the end of the section.

Distinguished Features Of Wsn

WSN has distinguished features over the traditional multi hop wireless networks. These features must be taken into account when designing control protocols for WSN. These features are related to: the deployment of sensor nodes, the resources constraints, the Quality of Service (QoS) requirement, and Data Traffic models