\end{figure}
\begin{enumerate} [(I)]
-\item \textbf{Sensing Unit:} consists of two main parts: sensors and analog to digital converters (ADCs). It responsible of sensing the physical phenomena and produce the analog signals to the ADC so as to convert it to digital data, and sends it to the computation unit.
-\item \textbf{Computation Unit:} The main purpose of this unit is to manage and manipulate the instructions that related to sensing, communication, and self-organization, which make the sensor node cooperates with other sensor nodes in order to perform the allocated sensing tasks. It composed of a processor chip, an active short-term memory for storing the sensed data, an internal flash memory for storing program instructions, and an internal timer.
-\item \textbf{Communication Unit:} It is responsible of all data transmission and reception of the sensor node that performed by the transceiver circuitry. A transceiver circuit composed of a mixer, frequency synthesizer, voltage-controlled oscillator (VCO), phase-locked loop (PLL), demodulator, and power amplifiers, all of which consume valuable power~\cite{ref19}.
+\item \textbf{Sensing Unit:} consists of two main parts: sensors and analog to digital converters (ADCs). It is responsible of sensing the physical phenomena and produce the analog signals to the ADC so as to convert it to digital data, and sends it to the computation unit.
+\item \textbf{Computation Unit:} The main purpose of this unit is to manage and manipulate the instructions that related to sensing, communication, and self-organization, which make the sensor node cooperates with other sensor nodes in order to perform the allocated sensing tasks. It is composed of a processor chip, an active short-term memory for storing the sensed data, an internal flash memory for storing program instructions, and an internal timer.
+\item \textbf{Communication Unit:} It is responsible of all data transmission and reception of the sensor node that is performed by the transceiver circuitry. A transceiver circuit is composed of a mixer, frequency synthesizer, voltage-controlled oscillator (VCO), phase-locked loop (PLL), demodulator, and power amplifiers, all of which consume valuable power~\cite{ref19}.
\item \textbf{Power Unit:} This unit represents the most significant part in wireless sensor node. It supplies the other units by the needed power.
\end{enumerate}
\begin{enumerate} [(I)]
-\item \textbf{Localization System:} It is important that the wireless sensor node equipped with a location finding system because it is necessary for many WSN applications. It is required by routing algorithms and sensing coverage algorithms, which are needing information about the location of the wireless sensor nodes. The location finding system composed of a Global Positioning System (GPS) or a discovery algorithm that executes a localization systems to provides information about the location of wireless sensor node using distributed computation.
+\item \textbf{Localization System:} It is important that the wireless sensor node is equipped with a location finding system because it is necessary for many WSN applications. It is required by routing algorithms and sensing coverage algorithms, which need information about the location of the wireless sensor nodes. The location finding system is composed of a Global Positioning System (GPS) or a discovery algorithm that executes a localization systems to provides information about the location of wireless sensor node using distributed computation.
-\item \textbf{Mobilizer:} The mobility function sometimes needed in many applications to move the wireless sensor node from one location to another so as to perform a certain task in WSN, so it will be necessary that the wireless sensor node equipped with the mobilizer system for such applications. A high energy consumption is needed to support the mobility in wireless sensor node, and it should be supported efficiently. The movement of wireless sensor node is controlled by the mobility function with cooperation with the sensing unit and the computation unit .
+\item \textbf{Mobilizer:} The mobility function is sometimes needed in many applications to move the wireless sensor node from one location to another so as to perform a certain task in WSN, so it will be necessary that the wireless sensor node equipped with the mobilizer system for such applications. A high energy consumption is needed to support the mobility in wireless sensor node, and it should be supported efficiently. The movement of wireless sensor node is controlled by the mobility function with cooperation with the sensing unit and the computation unit .
-\item \textbf{Power Generator:} Several WSN applications need to operate for a longer time, so it is essential to equip the wireless sensor node with additional power source in order to prolong the network lifetime. The better energy source to generate the power for outdoor applications is a solar cells. An another power harvesting mechanisims~\cite{ref20,ref21} for thermal, motion, vibration, micro water flow, Biological, pressure gradients, and electromagnetic radiation energy harvesting can be used that yield increasing power output to extend the network lifetime.
+\item \textbf{Power Generator:} Several WSN applications need to operate for a longer time, so it is essential to equip the wireless sensor node with additional power source in order to prolong the network lifetime. The better energy source to generate the power for outdoor applications is a solar cells. An another power harvesting mechanisims~\cite{ref20,ref21} for thermal, motion, vibration, micro water flow, Biological, pressure gradients, and electromagnetic radiation energy harvesting can be used that yield increasing power output to extend the network lifetime.
\end{enumerate}
\begin{figure}[h!]
\section{Types of Wireless Sensor Networks}
\label{ch1:sec:03}
-According to the physical phenomena for which the WSN is developed, several WSNs are deployed on the ground, underground and underwater, which suffer from different conditions and challenges. WSNs can be classified into six types, where five types of them presented in~\cite{ref4,ref5} and we added the sixth type. Figure~\ref{wsnt} gives an examples for WSNs types.
+According to the physical phenomena for which the WSN is developed, several WSNs are deployed on the ground, underground and underwater, which suffer from different conditions and challenges. WSNs can be classified into six types, where five types of them presented in~\cite{ref4,ref5}. Figure~\ref{wsnt} gives an examples for WSNs types.
\begin{figure}[h!]
\centering
\includegraphics[scale=0.5]{Figures/ch1/typesWSN.pdf}
\begin{enumerate}[(I)]
\item \textbf{Terrestrial WSNs:}
-The wireless sensor nodes are deployed over the land constructing a network of hundreds to thousands of sensor devices. Several applications are used terrestrial WSNs such as physical environmental sensing and monitoring, industrial monitoring, and surface explorations. The main challenges in this type of WSNs are ensuring coverage and connectivity with removing redundancy, energy-efficient routing, data communication reduction, balancing energy consumption, energy-efficient data aggregation. The work in this dissertation concentrate on this type of WSNs. This dissertation focused on this type of WSNs.
+The wireless sensor nodes are deployed over the land constructing a network of hundreds to thousands of sensor devices. Several applications are used terrestrial WSNs such as physical environmental sensing and monitoring, industrial monitoring, and surface explorations. The main challenges in this type of WSNs are ensuring coverage and connectivity with removing redundancy, energy-efficient routing, data communication reduction, balancing energy consumption, energy-efficient data aggregation. The work in this dissertation concentrates on this type of WSNs. This dissertation focused on this type of WSNs.
\item \textbf{Underground WSNs:}
-The wireless sensor nodes are deployed over caves, mines, or underground and communicate through soil~\cite{ref9,ref10}. The most important applications in underground WSNs are structural monitoring, agriculture monitoring, landscape management, underground environment monitoring of soil, water or mineral and military border monitoring. The essential challenges of underground WSNs are the high levels of attenuation and signal loss in communication, so it needs a certain type of devices so as to provide a robust wireless communication underground, menace to devices come from unsuitable underground conditions, replace or recharge the battery seems to be impossible, and the WSN deployment is high costly.
+The wireless sensor nodes are deployed over caves, mines, or underground and communicate through soil~\cite{ref9,ref10}. The most important applications in underground WSNs are structural monitoring, agriculture monitoring, landscape management, underground environment monitoring of soil, water or mineral and military border monitoring. The essential challenges of underground WSNs are the high levels of attenuation and signal loss in communication, therefore it needs a certain type of devices so as to provide a robust wireless communication underground, where the risk to devices come from unsuitable underground conditions; replace or recharge the battery seems to be impossible; and the WSN deployment is high costly.
\item \textbf{Underwater WSNs:}
A WSN is composed of a wireless sensor nodes deployed under the water such as the ocean~\cite{ref11,ref12}. There are many challenges should be faced in this type of WSN such as: the high cost of the underwater sensor devices; underwater wireless communication has limited bandwidth, high latency, signal fading, and long propagation delay problems; sparse deployment in which the wireless sensors should be able to self-organized to adapt with various condition of the ocean environment; and the limited power of the wireless sensor node battery as well as it is impossible or difficult to replace or recharge it led to look for about energy efficient underwater wireless communication mechanisms. The main applications, which are used by underwater WSNs are seismic monitoring, disaster prevention monitoring, underwater robotics, pollution monitoring, equipment monitoring, and undersea surveillance and exploration.
\section{Wireless Sensor Network Applications}
\label{ch1:sec:04}
-The fast development in WSNs has been led to extensive study on different characteristics of it. However, the WSN has been applied with concentrating on various applications. In this section, we demonstrated a different academic and commercial applications that developed for WSNs. The WSN composed of various types of sensors such as~\cite{ref17,ref19}: thermal, seismic, magnetic, visual, infrared, acoustic, and radar, which are capable of observing a different physical conditions such as: temperature, humidity, pressure, speed, direction, movement, light, soil makeup, noise levels, the presence or absence of certain kinds of objects, and mechanical stress levels on attached objects. So, There are a wide range of WSN applications and these applications can be classified into five classes~\cite{ref22}. Figure~\ref{WSNAP} shows classification of WSN applications.
+The fast development in WSNs has been led to extensive study on different characteristics of it. However, the WSN is concentrated on various applications. In this section, we demonstrate a different academic and commercial applications. The WSN is composed of various types of sensors such as~\cite{ref17,ref19}: thermal, seismic, magnetic, visual, infrared, acoustic, and radar, which are capable of observing a different physical conditions such as: temperature, humidity, pressure, speed, direction, movement, light, soil makeup, noise levels, the presence or absence of certain kinds of objects, and mechanical stress levels on attached objects. Thus, a wide range of WSN applications can be classified into five classes~\cite{ref22}. Figure~\ref{WSNAP} shows classification of WSN applications.
\begin{figure}[h!]
\centering
\begin{enumerate}[(I)]
-\item \textbf{Health-care Applications:} There is increasing interest and extensive research in the health-care applications. Two types of health-care systems are recognized~\cite{ref22}: vital status monitoring and remote health-care surveillance. In vital status monitoring applications, Patients are wearing the sensors in order to oversee the state of their health and to allow medical staff to respond efficiently.The most general used vital signs are ECG, pulse oximetry, body temperature, heart rate, blood pressure~\cite{ref27}. These applications includes: mass-casualty disaster monitoring, vital sign monitoring in hospitals, and sudden fall or epilepsy seizure detection. On the other hand, remote health-care surveillance is related to the health services that do not require constant presence of health care. These applications includes: elderly monitoring; providing support to a physically impaired person; gather clinically relevant information for rehabilitation supervision~\cite{ref28}; location tracking and medication intake monitoring~\cite{ref27}.
+\item \textbf{Health-care Applications:} There is increasing interest and extensive research in the health-care applications. Two types of health-care systems are recognized~\cite{ref22}: vital status monitoring and remote health-care surveillance. In vital status monitoring applications, patients are wearing the sensors in order to oversee the state of their health and to allow medical staff to respond efficiently.The most general used vital signs are ECG, pulse oximetry, body temperature, heart rate, blood pressure~\cite{ref27}. These applications includes: mass-casualty disaster monitoring, vital sign monitoring in hospitals, and sudden fall or epilepsy seizure detection. On the other hand, remote health-care surveillance is related to the health services that do not require constant presence of health care. These applications includes: elderly monitoring; providing support to a physically impaired person; gather clinically relevant information for rehabilitation supervision~\cite{ref28}; location tracking and medication intake monitoring~\cite{ref27}.
-\item \textbf{ Environment and agriculture Applications}
-The increasing development in WSNs led to use it extensively for monitoring the environment and agriculture. There are several WSNs applications have developed to the precision agriculture, cattle monitoring and environmental monitoring.
+\item \textbf{ Environment and agriculture Applications:}
+Several WSNs applications have been developed to the precision agriculture, cattle monitoring and environmental monitoring.
-Precision agriculture refereed to the science of using the innovative and modern technology to improve the crop production, where, the WSNs are the main technology for developing of precision agriculture~\cite{ref29}. Those technology contributes in increasing the agricultural yields, improving quality, and reducing costs whilst decreasing the damaging impact for the environment. The wireless sensors are distributed over the target feild so as to monitor the main parameters such as~\cite{ref22}: soil moisture, atmospheric temperature, creating a decision support system. The wireless sensors can be used in agricultural services like Irrigation, fertilization, pest control, animal and pastures monitoring, horticulture(e.g., greenhouse and viticulture)~\cite{ref30}.
+Precision agriculture refers to the science of using the innovative and modern technology to improve the crop production, and the WSNs are the main technology for developing of precision agriculture~\cite{ref29}. This technology contributes in increasing the agricultural yields, improving quality, and reducing costs whilst decreasing the damaging impact for the environment. The wireless sensors are distributed over the target field so as to monitor the main parameters such as~\cite{ref22}: soil moisture, atmospheric temperature, creating a decision support system. The wireless sensors can be used in agricultural services like Irrigation, fertilization, pest control, animal and pastures monitoring, horticulture(e.g., greenhouse and viticulture)~\cite{ref30}.
-In cattle monitoring applications, the WSN used to livestock control and monitoring such as: virtual fencing for extensive grazing systems, animal behavior study, health monitoring, to detect disease breakouts, to localize them and to control end-product quality (meat, milk).
+In cattle monitoring applications, the WSN is used to livestock control and monitoring such as: virtual fencing for extensive grazing systems, animal behavior study, health monitoring, to detect disease breakouts, to localize them and to control end-product quality (meat, milk).
Various WSN applications for environmental monitoring have been used in coastline erosion, air quality monitoring, safe drinking water and contamination control~\cite{ref22}.
-\item \textbf{Public safety and military systems Applications}
+\item \textbf{Public safety and military systems Applications:}
The WSNs can be incorporated into military command, control, communications, computing, intelligence,
-surveillance, reconnaissance, and targeting systems. It estimates the unpredictable events such as natural disasters and threats as well as some of the military WSN applications keep under surveillance friendly forces, equipment, and ammunition; battlefield surveillance; reconnaissance of opposing forces and terrain; targeting; battle damage assessment; and nuclear, biological, and chemical (NBC) attack detection and reconnaissance~\cite{ref19}. According to figure~\ref{WSNAP}, the public safety and military applications are categorized into active intervention and passive supervision~\cite{ref22}. In active intervention systems, the wireless sensors are portable with the agents and is devoted to the security of the team activities. During the work of the team, the leader will monitor the agents situation and the environmental impact factors. The main applications includes: emergency rescue teams, miners and soldiers. In passive supervision systems, the wireless static sensors are scattered over a large field for monitoring a civil area or nuclear site for a longer time. These applications includes: surveillance and target tracking , emergency navigation, fire detection in a building, structural health monitoring and natural disaster prevention such as in the case of tsunamis, eruptions or flooding.
+surveillance, reconnaissance, and targeting systems. It estimates the unpredictable events such as natural disasters and threats as well as some of the military WSN applications keep under surveillance friendly forces, equipment, and ammunition; battlefield surveillance; reconnaissance of enemy forces; targeting; battle damage assessment; and nuclear, biological, and chemical (NBC) attack detection and reconnaissance~\cite{ref19}. According to figure~\ref{WSNAP}, the public safety and military applications are categorized into active intervention and passive supervision~\cite{ref22}. In active intervention systems, the wireless sensors are portable with the agents and is devoted to the security of the team activities. During the work of the team, the leader will monitor the agents situation and the environmental impact factors. The main applications includes: emergency rescue teams, miners and soldiers. In passive supervision systems, the wireless static sensors are scattered over a large field for monitoring a civil area or nuclear site for a longer time. These applications includes: surveillance and target tracking , emergency navigation, fire detection in a building, structural health monitoring and natural disaster prevention such as in the case of tsunamis, eruptions or flooding.
-\item \textbf{Transportation systems Applications}
-The fast development in the domain of Intelligent Transport Systems (ITS) ranging from flight transport and traffic management to in-vehicle services like driver alert or traffic monitoring. As a result, the transportation data collection and communication represent a major role in the ITS~\cite{ref37}.
-The WSNs can be integrated with the transportation systems such as traffic monitoring, real-time safety systems, and commercial services~\cite{ref22}. In traffic-monitoring systems, The wireless sensors are embedded within or across the pavement and some sensors are installed above or on the side of roads so as to collect the informations related to the traffic~\cite{ref36}. These WSN traffic systems are used to detect the vehicles, vehicle count, and classification. In safety applications, the wireless sensors are employed to deal with many cases such as: driving safety~\cite{ref41}, vehicle safety~\cite{ref38}, where many wireless sensors are scattered on roads or vehicles, collaborating through Vehicle-to-Vehicle, Vehicle-to-Roadside, and Vehicle-to-Infrastructure communications. Extensive research in these domains, which are concentrated on preventing the collisions among vehicles by Vehicle-to-Vehicle communications~\cite{ref40}. In addition, commercial applications are can be given by service providers. They include route guidance to avoid rush-hour jams, smart high-speed tolling, assistance in finding a parking space and automobile journey statistics collection~\cite{ref22}.
+\item \textbf{Transportation systems Applications:}
+The fast development in the domain of Intelligent Transport Systems (ITS) ranging from flight transport and traffic management to in-vehicle services like driver alert or traffic monitoring. As a result, the transportation data collection and communication represent a major role in the ITS~\cite{ref37}.
+The WSNs can be integrated with the transportation systems such as traffic monitoring, real-time safety systems, and commercial services~\cite{ref22}. In traffic-monitoring systems, the wireless sensors are embedded within or across the pavement and some sensors are installed above or on the side of roads so as to collect the informations related to the traffic~\cite{ref36}. These WSN traffic systems are used to detect the vehicles, vehicles count, and classification. In safety applications, the wireless sensors are employed to deal with many cases such as: driving safety~\cite{ref41}, vehicle safety~\cite{ref38}, where many wireless sensors are scattered on roads or vehicles, collaborating through Vehicle-to-Vehicle, Vehicle-to-Roadside, and Vehicle-to-Infrastructure communications. Extensive research in these domains are concentrated on preventing the collisions among vehicles by Vehicle-to-Vehicle communications~\cite{ref40}. In addition, commercial applications can be given by service providers. They include route guidance to avoid rush-hour jams, smart high-speed tolling, assistance in finding a parking space and automobile journey statistics collection~\cite{ref22}.
-\item \textbf{Industry Applications: Manufacturing and smart grids}
-The most significant goal for many companies is the automation of controlling and monitoring systems in many application such as: manufacturing, water treatment, electrical power distribution, and oil and gas refining. The WSNs is incorporated in Supervisory Control and Data Acquisition (SCADA) systems and Smart Grids~\cite{ref22}. SCADA systems are a computer softwares by which the industrial processes in factories are controlled and supervised. The wireless sensors are used with actuators to control the factory, detection of liquid/gas leakages, and inventory management. These applications are needed for precise monitoring of temperature, shock, and noise factors in remote locations such as tanks, turbine engines or pipelines. In Smart Grids, the goal is to supervise the energy supply and consumption operation. The main WSN applications in smart grid includes: sensing the relevant parameters affecting power output (pressure, humidity, wind orientation, radiation, etc.); control of turbines, motors and underground cables; home energy management; and remote detection of faulty components.
+\item \textbf{Industry Applications: Manufacturing and smart grids:}
+The most significant goal for many companies is the automation of controlling and monitoring systems in many applications such as: manufacturing, water treatment, electrical power distribution, and oil and gas refining. The WSNs is incorporated in Supervisory Control and Data Acquisition (SCADA) systems and smart grids~\cite{ref22}. SCADA systems are a computer softwares by which the industrial processes in factories are controlled and supervised. The wireless sensors are used with actuators to control the factory, detection of liquid/gas leakages, and inventory management. These applications are needed for precise monitoring of temperature, shock, and noise factors in remote locations such as tanks, turbine engines or pipelines. In Smart Grids, the goal is to supervise the energy supply and consumption operation. The main WSN applications in smart grid includes: sensing the relevant parameters affecting power output (pressure, humidity, wind orientation, radiation, etc.); control of turbines, motors and underground cables; home energy management; and remote detection of faulty components.
\end{enumerate}
%\section{Protocol Design Requirements}
\section{The Main Challenges in Wireless Sensor Networks}
\label{ch1:sec:05}
-There are many challenges need to be faced in WSNs, which are received increasing attention by a large number of researchers during the last few years. These challenges were the reason in proposing different solutions so as to face these challenges as will be explained in next section~\ref{ch1:sec:06}.
+Many challenges need to be faced in WSNs, which are received increasing attention by a large number of researchers during the last few years. These challenges were the reason in proposing different solutions so as to face these challenges as will be explained in next section~\ref{ch1:sec:06}.
\begin{enumerate} [(I)]
\item \textbf{Extended Network Lifetime:} one fundamental issue in WSNs is how to prolong the network lifetime as long as possible. Since sensor battery has a limited power; and since it is difficult to recharge or replace it especially in remote or hostile environment; It is necessary to reduce the energy consumption by using energy-efficient methods so as to extend the network lifetime.
\subsection{Energy-Efficient Routing}
The energy-efficient routing is a significant factor to the design of WSN protocols in order to satisfy the main constraints in the hardware, power, and other resources of wireless sensor nodes~\cite{ref42}. There are many challenging factors need to be taken into consideration during designing a routing protocol for WSN, like: Limited energy capacity, Node deployment, Sensor location, Dynamic network, Hardware resource constraints, Data aggregation and gathering, Latency, Scalability, and Fault tolerance.
-
\subsubsection{Routing Metric based on Residual Energy} lifetime maximization can be achieved by using the residual power of wireless sensor node as a routing metric and take it into account during executing the routing protocol in WSNs. So, the routing protocols should concentrate on the remaining power of sensor nodes during taking the decision to select the next hop toward the destination and not depend on the shortest path solution. It prioritizes routes on the basis of an energy metric (sometimes with other routing metrics) so it is called energy-aware routing protocols~\cite{ref45,ref46}.
