Wireless Sensor Networks and Its Types

1.0 Abstract

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Wireless sensor networks (WSANs) are a group of sensors and actors that are linked by a wireless medium for the purpose of performing distributed sensing and action on a given task. This involves the sensors collecting information about the surrounding physical environment and sending the information to the actors which take the decisions and perform some needed action, basing on the information received from the sensors about the surrounding environment. These sensor networks are sometimes referred to as wireless sensor and actuator networks. They monitor physical or environmental conditions such as sound, pressure, temperature among others and send the collected data to the required location.

Effective sensing and acting require a distributed local coordination methods and mechanisms among the sensors and the actors in addition to this, sensor data should be valid in order for right and timely actions to be performed. This paper describes secure routing in wireless sensor networks and outlines its threats on security.

Keywords: Wireless sensor and actor networks; Actuators; Ad hoc networks; Sybil attack; Real-time communication; Sinkhole; Routing; MAC; adversary.

2.0 Introduction

With the recent rapid improvement in technology, many networking technologies have been created to make communication easy. One such technology is distributed wireless sensor network which has a capability of observing the physical world and process the data and, in addition, makes decisions basing on the collected data and perform actions basing on this. Wireless sensor networks (WSNs) are rapidly growing and have emerged as one of the important areas in mobile computing. These applications of WSNs are numerous and growing fast with time. These applications are increasing and are currently deployed in both home and offices and also outdoor such as mapping the territory of an enemy in the battle ground as mentioned by Akyildiz et al (2002). It is used in a military environment; the technology is used to detect the enemy soldiers and trucks. They are also used in healthcare for detecting intruders mostly on healthcare of the elderly; they are connected to the wireless home security systems.

Routing security of the wireless networks is always considered in the above-mentioned scenarios and the accuracy of relaying information is always the target after and during the deployment of the wireless systems. A lot of the routing protocols have been designed and deployed in the market each focusing on security as an objective of obtaining its optimum user requirements. However, none of the systems have been able to achieve the goal of security. Many security challenges still exist that expose this technology to threats. This is due to combined threats which are as a result of physical security and lack of adequate resources, which motivate the intruders who may compromise the sensor nodes if the system is not secure enough.

The primary goals of wireless secure networks are data authentication, data confidentiality, data integrity, and data availability.

Data authentication will ensure that the message being transmitted is reliable; this is achieved by identifying the place that the transmitted message originates from. This ensures that alteration of the packets by an adversary is avoided. An adversary may inject the wrong or additional packets to the message and the only way of identifying this is identifying the origin of the message. Authentication of data is achieved by sending and receiving nodes sharing the secret codes or keys. It is however very difficult in a wireless network to attain authenticity of the information due to the nature of the wireless network.

Confidentiality of data, on the other hand, involves the transmitted information being hidden or concealed so that an attacker is not aware of the message being transmitted from the network, therefore, shielding the attacker from compromising the information.

Another key important goal is data integrity. This ensures that the data is reliable and has not been tampered with or altered in any way. According to Shanmugapriya and Padmavathi (2009), even if the network has all the confidentiality measures, there is still a possibility that data integrity can be compromised by alteration. Alteration of information can render the data useless due to its unreliability.

Data availability is also another key important aspect of a wireless sensor network. It determines the availability of the network resources to communicate. Failure of a node or a base station will lead to the failure of the entire network and, therefore, operations in the network will be rendered unavailable.

Other goals of WSNs involve the freshness of the data; this is achieved by ensuring that the data in the network is as recent and updated as possible. Data freshness ensures that the old messages are not replayed in the network. Independence of the network also ensures that every sensor self-organizes itself and is as flexible as possible; this allows self-healing after the attack. The main aim in WSNs is secrecy and authentication, since most of these sensor networks and various applications that rely in these networks require protection against various challenges as far as security is concerned, such as malicious injections, eavesdropping, and packet modification, encryption of the packets is the best approach to fighting back against these emerging threats. This ensures that high level of security is achieved by the keys being set to decrypt the information on the other end. Methods such as link-layer cryptography, for instance, ensure that there is one key which simplifies the key setup. Another issue which the wireless sensor networks try to address is privacy. However, the above-mentioned goals are facing various challenges from the attacks and injections carried out by adversaries on the network. Various protocols have been defined to try to reduce these challenges in the wireless sensor networks.

3.0 Research Methods

3.1 Introduction

This chapter discusses the methodological approaches that will be used in the investigation of secure routing in wireless sensor networks. The chapter will describe the research design, comparative analysis, statistics of survey, techniques that will be used for data gathering, and data analysis techniques.

3.2 Research Design

This research adopts the case study research approach. This research will be based on the research studies performed by other researchers and drawing conclusions after a thorough analysis and considerations of people, events and activities that have occurred in the field of wireless sensor networking. This method is useful in gaining a wide understanding on the issue the research is all about.

3.3 Research Techniques

Below are some of the techniques used in this research.

Performance Analysis

This is an objective method of recording performance so that key elements of that performance can be quantified in a valid and consistent manner.

In this work, Srabanty & Sazzad (2013), for instance performed an investigation on the performance of wireless networks using several types of digital modulation techniques. This study was based on a double-transmit and multiple-receive antenna supported wireless communication system that employs single user Alamoutis STBC and MRC scheme on secured text message transmission. This research, on the other hand, uses performance analysis to gauge the performance of various power consumption protocols, efficiency and security.

Comparative Analysis

This methodology compares the various protocols with others and at the end draws the conclusion on which one is the best in terms of performance and efficiency. This methodology also has been used to compare various WSNs attacks and the danger each one poses to the network and its magnitude. Here is the sample comparative analysis.

3.4 Conclusion

The methods used to carry out research as indicated above were helpful in supplying the required data as far as the needed information is required. Although the methods used are accurate, the methods were not enough to get all the facts from the field since the needed facilities to conduct a thorough research are scanty. The information acquired was very useful in drawing the conclusions.

3.5 Recommendation

In future, the research should be thoroughly carried out in a wide variety of environments to come up with a real field experience and recommendations.

In the sections that follow I will be presenting the routing protocols and the security challenges experienced by wireless sensor networks and at the end give secure measures of addressing these issues.

Routing is the process of selecting the best path in a network where messages are passed from one node to another until the message reaches the intended destination. A protocol, on the other hand, is the set of rules that communicating nodes must adhere to in a network. Routing in WSNs differs from that of wired networks in many ways, this is due to the lack of infrastructure and the unreliability of the wireless links which may cause communication to fail. The wireless network uses less energy and, therefore, routing protocols defined must meet this requirement. This has led to the development of the routing algorithm to meet these challenges in the wireless network environment. These protocols have been categorized into seven categories as I will describe below.

4.0 Routing Protocols

Location based protocols

This protocol location is based where the sensor nodes are addressed by the location information. The information about the location of the sensor nodes is requested by the protocol and the distance between two nodes which are specified calculated basing on this information. The consumption of the energy is then estimated basing on the result obtained from the calculation. Examples of location based protocols are Geographic Adaptive Fidelity (GAF), Geographic and Energy-Aware Routing (GEAR), Coordination of Power Saving with Routing, Geographic Random Forwarding (GeRaF) among others.

Geographic adaptive fidelity (GAF) is a routing protocol which considers energy usage in the transmission of packets across the network. This protocol turns off some sensors it deems as unnecessary and in the process ensures that routing is as constant and uninterrupted as possible...