Zigbee is based on the IEEE 802.15.4 standard wireless protocol. The main purpose of Zigbee is to send small packets or data's between the devices, unlike the Bluetooth which is used to send large packets. Zigbee is found mainly for the low-power devices and it will help the packets or data's to send quickly. It is both power and cost effective. Since it uses only low power, its battery life is longer when compared to the other devices. The battery life may last for years with just even the AA or AAA batteries. The main aspect about the Zigbee is that it supports Mesh topology, which has multiple paths connected to the nodes. It also supports other networks such as point- to- point, point-to-multipoint and many others. Since it needs only low power and it is reliable without collision avoidance, it is widely being used in the industries.
The Physical layer deals with the data and the connectivity, and even about the frequency in which the data are sent. The MAC layer is the Media Access Control Layer and it takes care of the controlling the data access which are on the process. And the MAC layer protocol is used here. The Network layer is about the network functions such as the routing, and connecting the devices and nodes with one another and so on. It tells the address of the network and also maps the routes to make it easier. The application layer is the top most layer which just deals with the process and the application which takes place after the network connectivity is done. It mostly related to the software part which is spread widely over the nodes. And the important part about the Zigbee Wireless Sensor Network is that the security can be provided in all the levels of layers and that is the reason that it is very reliable.
Background:
A number of authors or writers have mentioned in their books and papers that the main purpose of using the Zigbee Wireless Sensor Network is because it is fast, it costs low, it is reliable and also it consumes only less power when compared to the other wireless devices. And so when this is used in our daily life then the people can be benefitted a lot by it. The Zigbee Wireless Sensor Network also has much importance, and it can be used in almost all walks of life such as in hospitals, houses, industries and so on. But the main problem which is there now is that not much people are making use of this technology because lots of other devices are there in existence. So if more people are aware of this technology and starts using it they will be benefitted in many ways.
About Zigbee:
The Zigbee protocols uses data's which are of low rate. This is cost effective and can be used anywhere such as companies, offices or even for homes. It can be used for various purposes such as alarm in the parking lot, in traffics, offices etc. It is very useful as it saves power and also cost effective. Many protocols are used in the Zigbee wireless sensor networks in order to see the performance such as the Zigbee protocol, MAC layer protocol, Modbus protocol. Different protocols are used by the people depending upon their study and the design.
Even though there are a lot of wired applications which are used in the day-to-day lives, in the industries, the cost of cabling and man-power will be very expensive than the networks. So, when the applications such as the Zigbee wireless networks are used it would also be cost effective and easy to install. It can easily be used in the industries by cutting the cost, unlike the wired networks. And also the wireless networks are more flexible when compared to the wired networks and it is easy to monitor. As it is used in the industries, some of the problems which the industries might face should be resolved such as the reliability, consumption of the power and the distance which they are communicated. A Zigbee adapter was found without any external batteries. And later a wireless monitoring system of the Zigbee was developed. It has 3 different types of nodes such as the sensor nodes, sink nodes and the gateway nodes.
Uses of Zigbee:
Patrick Kinney (2003) has written in his paper about the use of the Zigbee in many places and much effective it is when compared to the other wireless devices. He has discussed about the different layers in it with its functions. He (Patrick Kinney (2003)) has also mentioned that the Zigbee is more secure as it starts from the MAC level security itself and also the Network layer contains more security things which are required. He has concluded saying that Zigbee wireless Sensor Network has more prospects when compared to the other devices and he has also made comparison between the Zigbee and the Bluetooth device and stated that Zigbee is more effective in almost all the aspects.
In Home Automation:
Few scientists such as Yang Li, Ji Maorong, Gao Zhenru, Zhang Weiping, and Guo Tao (2009) have proved that the Zigbee wireless sensor network is very useful and it is suitable for the home automation. And they also proved and agreed that it is very practical. They also stated that among the other technologies such as the Bluetooth, Wi-Fi and so on, this Zigbee will be more suitable and reliable as it is both cost efficient and power efficient. It can be easily used in the short distances and it also has longer battery life. They also divided it into 2 parts such as Full Function Devices (FFD) and Reduced Function Devices (RFD). All the work which is done by the FFD cannot be performed by the RFD. As they use the Zigbee for the home automation they divided the network into two types such as the inner network and the outer network. And even though Zigbee supports many kinds of networks they chose to use the star network as it would be of less cost and also the connections can be done in an easy way. The FFD is taken as the coordinator and RFD are taken as the end nodes so that the RFD only can communicate with the FFD (Coordinator).
CC2430 chip is designed to specifically use for the IEEE and the Zigbee applications, The Zigbee coordinator takes care of all the functions and the performances. By designing the chip CC2430, it is not only used in the practical way but it can also be used to develop the home automation and the digital process and devices.
An author named Roberto Verdone() has confirmed in his book that the Wireless sensor network comes under the IEEE 802.15.4 and specifically the (LR-WPAN) Low-rate Wireless Personal Area Network and it also promises that Zigbee is one of its standards. The Zigbee is very efficient in the power, cost and as it is very reliable. Both audio and video streaming can be performed using the Zigbee wireless networks. But the main drawback in this book is that the author only tells us the results based on the simulation which is been performed and he has not implemented it in the real time scenario and so we are not sure about the results in the real time. The Zigbee protocol also depends on the IEEE 802.15.4 standard. He has mentioned in the book that the payload data can be sent only up to the level of 127 bytes and it is been defined by the Physical layer. And that it cannot bear a large or heavy payload more like the other wireless devices as it is mainly designed to do the work effectively. In this paper he has evaluated the performance by the streaming method. He has implemented his finding in an indoor environment and in his paper he has mainly focused about the Voice streaming. And he has concluded that Zigbee not only deals in improving the hardware parts and the deployments but that it also deals with the standard specification.
Improved Connectivity:
In 2008, Tian-Wen Song and Chu-Sing Yang found a method to improve the connectivity of the wireless sensor networks and also proved it in their simulation. They stated that due to the deployment problems faced by the wireless devices, the networks may be unreached and it might also end up in more deployment costs. So, in their paper they found an improved connectivity to overcome this problem. They also mentioned that the specification which was done at last was in the year 2007.
They have criticized that even there were different papers written by many people about the various uses and functions of the Zigbee network, but no one dealt with the protocol and the database issues and that the connectivity and the network is an important aspect and that it should have been taken into consideration and improved. And even though the Zigbee performs many functions, if the network is not proper, it might lead to various problems and so they have improved the connectivity in their paper.
Power Consumption:
In the same year, few scientists from Pune(Shah, P., Shaik)h, T., Ghan, K., and Shilaskar, S. (2008)) have proposed a paper about the management of power consumption in the Zigbee Wireless Sensor Networks. Power consumption is the major problem which is faced throughout the world. Whatever devices we use in real life consumes more power and that a few devices consumes a lot. And so, in this paper they (Shah, P., Shaik)h, T., Ghan, K., and Shilaskar, S. (2008)) have discussed about how to manage the consumption of power using the Zigbee Wireless Sensor Networks. Because of the power problems there are many and with more areas without power, they have suggested that instead having a power cut, they can just ignore using the devices which consumes more power such as the AC, heaters, etc. This way they can save power. They have created a Wireless Sensor Network which runs on the full-duplex mode. And because Zigbee consumes only less power when compared to many other wireless devices and it will be power efficient, and so the management of the power can take place in a proper way. They have used the Zigbee protocol to perform this process. They have further mentioned why they have used Zigbee and also mentioned the difference between Zigbee and the Bluetooth. They have stated that the main purpose of using Zigbee is because it is an open standard protocol and that it consumes only less power and it is of low cost. They have also stated that it is very reliable when compared to the other networks and that it provides more security.
And the other main reason for using Zigbee is that it can be used in the mesh network, so it can be an easy mode to communicate to all the nodes and out of all it can be expanded whenever needed without any issues. The Zigbee Wireless Sensor Networks are also used in the other topology such as the Star topology, tree topology and so on. The researchers have concluded saying that if people start using this they will find a drastic change and also that it will be more effective and efficient.
Gary Legg
Monitoring the environmental applications:
In 2009, few authors from China made a project about the Zigbee network which is used in monitoring the environmental applications. They did it on the CC2430 board to verify the correctness and working of the Zigbee Wireless Sensor Network. There are lots of environmental issues which we face in our day-to-day life and so if the activities are monitored in a proper way lot of problems may be solved and also reduced. With the help of the Zigbee Wireless Sensor Network we will be able to monitor the pesticides which are sprayed for the crops, about the Soil, and even about the fertilizers. They have also mentioned that compared to the other devices such as the Bluetooth, Wi-Fi etc, the use of Zigbee will be more effective and it will have a great ability in the lower transition rate and that the capacity of the network is very high. In this they have used the 2 main layers PHY layer and the MAC layer. The physical layer deals with the frequency and controls it and the MAC layer control the access of the radio channel. They have also added saying that people who use the technology in agriculture are using the tools and machinery to control the process happening and instead of using the old technology if they use this Zigbee wireless sensor network they can monitor all the agricultural activities. They can even monitor the use of soil, water, temperature, dew point and many other things, and mainly because it is reliable, cost effective and saves power. After implementing their ideas in the design, they have concluded that they have tested the performance and they have also implemented the function in China and that it has been very successful. And it will be great if the people start implementing it in their real life's and agriculture.
IEEE1451 Standard:
Three authors from Spain, Higuera, J., Polo, J., and Gasulla, M. (2009) made a complaint about the implementation of the Zigbee networks in the IEEE1451 standard. They have mentioned that Zigbee works mainly with the IEEE802 standard and if the standard is increased to the IEEE1451 the interoperability might have increased. And they also criticized that the few authors who has said that few other devices such as the Wi-Fi and Bluetooth function is improved by using the IEEE1451 standard and they have also used it in Zigbee. But there are no solution found for the Zigbee IEEE1451 network till now and they have stated the complaint in their paper. And they took some aspects and worked on it, and finally they (Higuera, J., Polo, J., and Gasulla, M. (2009)) implemented and complained about the Zigbee wireless sensor network and they also proposed the PHY TEDS in Zigbee which is to be included in the IEEE1451 standard in the future.
Improved Design:
Later in the year, Lui Yanfi Wang Cheng Qiao Xiaojun Zhang (2009) found and created an improved design of the Zigbee wireless sensor network. He said that even though it is a new and a useful technology there were few problems when it dealt with the processing. There were some time delay of the information sent, loss of packet data was found and the nodes were out of control. Even though there were some algorithms which were created to improve the efficiency they were all based on the software side. So, in his paper he created a design which deals with the processing in a distributed way. He created the network into three ways and thus it improved the wireless network in a great way.
In the improved network they (Higuera, J., Polo, J., and Gasulla, M. (2009)) proposed various sensors, nodes, processors and computers as host. The process deals from the nodes sent from the Zigbee till the processor deals with the information. And they also created the process so that there is no direct relationship between the Zigbee wireless sensor network and the host which is present, unlike the traditional and the original Zigbee network. And also, different protocols were chosen for the communication. For the communication between the processor and the host he chose the Modbus protocol. The Zigbee wireless sensor network was also designed in such a way to improve the performance. But the working and process is similar to the traditional network, and only the design is changed.
In Medical Fields:
In the next year Dayu He (2010), in his paper has told how the medical fields are using the Zigbee based Wireless Sensor Networks. He has stated that the Zigbee is used in the medical field, as many patients face problems about the technology which is used now and that most of it is outdated. And so, even the people who wished to use the Zigbee based wireless sensor networks in the medical fields thought that it will be very effective. He has also mentioned that the Zigbee, if it is used in the medical field, has lot of potential. The medical examinations which are being in practice are very complex for both the doctors and the patients as it has to go through the entire connectivity problem.
The devices like Bluetooth are being used now in the current field. But Zigbee based wireless sensor networks would be more useful and effective than the other devices as it requires only low cost and power. It is also highly reliable. The Zigbee provides lot of information about the patients and their temperature and even their pulse rate can be checked as it also saves a lot of time with the patients. As the patients can be monitored by the doctors it will be easy for them to check the patients and it will also be useful for the elderly people in many ways. The Zigbee can also be used in taking the ECG report of the patient. It can be connected through the Zigbee and the doctors can view the results through the Internet. It can also be used to monitor the hospitals which will be connected to the central system. They can monitor the service which the patients receive and they can store it in the database so that the records of each patient can be maintained properly.
But finally the author (Dayu He, 2010) concludes that even though Zigbee has so many advantages in the medical field, it is not that widely used because of some reasons like connection, extension etc. But if when people start using it, it will be of great use to them. He ends up saying that after it is being used in the medical field, it will be of great help to the patients and it will provide a major benefit to the society.
Technology:
Zheng Jijie and Xiang Xinjian mentioned in their paper that the key technology of the Zigbee WSN is the data processing technology. But in the current scenario the Zigbee Wireless Sensor Network has some problems like storing the information and excess of data. So, in their paper they introduced an event processing complex technology and that it has effective data analysis method also stated that the application which will be used in the future will be very effective. They have also mentioned that in the future the Zigbee Wireless Sensor Network technology will be very useful in all the fields. They divided it into two parts called the Zigbee Central Processing node and Zigbee Wireless Sensor node.
The Zigbee had many different features when compared to the other common data. The data's are correlated to each other and the time of the object, and it also has significant richness. But they have criticized that the Zigbee Wireless Sensor Networks faced some problems such as the inaccuracy and some error problems and that the Complex Event Processing (CEP) will be very understandable and useful in the event-driven information and that the problem could be solved. This paper is mainly about the excess of data and the shortage of information in the Zigbee Wireless Sensor Network, and so they have introduced Complex Event Processing Technology (Zheng Jijie and Xiang Xinjian) to it and it will be very useful to all the different types of users.
Application:
Changjiang Li, Yufen Wang, Xiaojuan Guo in their paper has researched about the application of the Wireless Sensor Network which is based on the Zigbee. And have added that Zigbee technology is a kind of bi-directional Wireless Communication or the Wireless Network Technology (Changjiang Li, Yufen Wang, and Xiaojuan Guo). One of the important characteristics of the Zigbee is its Network function and it varies from the other network devices. Even though Zigbee consumes only less power, its capacity is very large and also the time delay is very short. The protocol Stack of the Zigbee is not even half of that of the Bluetooth technology or the IEEE 802.11 standard, and it is made simpler for its effective used and reduced cost. And the security patterns are also very high and effective as it consists of 3 levels.
The writers (Changjiang Li, Yufen Wang, and Xiaojuan Guo) have concluded saying that even though the impact of the Wireless Sensor Networks have been there in the people's mind for many years for now, it had been used only in the labs or by the scientists because of its high costs and heavy power consumption. But anyway after the fast development of this Zigbee Wireless Sensor Network, it will spread widely throughout because of its cost and power efficiency and people might use it widely in all the fields like environmental management, medical fields and so on.
Protocol Stack of the Zigbee:
Greg Hackmann
Wireless Sensor Network Protocol:
The Wireless Sensor Network consists of different types of protocols such as the Zigbee protocol, ADOV protocol, Modbus protocol, MAC layer protocol and so on. The protocols are being used in different designs based on its use and the scenario.
Modbus Protocol:
Liu Yanfei, Wang Cheng, Yu Chengbo, Qiao Xiaojun (2009) made a research about the Zigbee Wireless Sensor Network and its applications using the Modbus protocol. They have mentioned that a friendly interface cannot view the information which is available in the Zigbee Wireless Sensor Network in the real time. But by using the Modbus protocol in the Zigbee this might be possible. In the paper they have described how to set in the Modbus protocol in the Zigbee WSN and to control the device. They have also implemented in the monitoring system of the plant ecology.
The Zigbee is useful in many places like home, industries, games and various other places. And they (Liu Yanfei, Wang Cheng, Yu Chengbo, Qiao Xiaojun (2009)) have made this research to use the Zigbee in the agricultural environment and controlling it. The Modbus protocol works in the application layer, as it deals with the communication between different types of devices and so it is inserted in the seventh layer of the OSI model. And to implement this process both the hardware and the software functions are being used. And once it is connected as required, the information of the plant and its physiological change can be analyzed in the monitor which is connected to the device. For the monitoring purposes few devices are needed like host computer, coordinator, sensor and the sensor node, so that they can communicate with one another and the required output will be obtained.
- Liu Yanfei, Wang Cheng, Yu Chengbo, Qiao Xiaojun (2009)
Proving that the Zigbee Wireless Sensor Networks can be used in the monitoring system of the Plant physiology, they have also mentioned few of its advantages. Liu Yanfei, Wang Cheng, Yu Chengbo, Qiao Xiaojun (2009) have concluded with the advantages stating that the Wireless Sensor network is very convenient and easy to install and the Modbus protocol creates a friendly environment. They have also mentioned that this system can be used also with the GRPS (General Packet Radio Service) and that the system can be expanded well as required.
Disadvantages:
A few authors have described the disadvantages of the wireless sensor network that due to the message relying, the network latency is increased (Kohvakka et al. 2006). They have further stated that if the Zigbee router faces and problems or it fails, then all the other nodes which are connected to it will be affected.
Greenhouse Monitoring:
ZHANG Qian†, YANG Xiang-long, ZHOU Yi-ming, WANG Li-ren, GUO Xi-shan(2006,2007) have also explained deeply about use of the Zigbee Wireless Sensor Networks in the Greenhouse monitoring and in its controlling. He has added more points and stressed the point saying that the Zigbee Wireless Sensor Networks has lot of advantages when compared to the other similar devices in various aspects like power, cost, and reliability and so on. And the futher notes tells us the this Wireless Sensor Network much better in the Greenhouse monitoring system when compared to the other wireless devices.
Conclusion:
Zigbee Wireless Sensor Network is based on the IEEE 802.15.4 standard protocol and it supports all kinds of networks such as Point-to-Point network, Point-to-Multipoint Network and so on. And it is commonly used in the topologies such as the Star topology, Tree topology and Mesh topology. Even though there are many Wireless devices such as the Bluetooth, Wi-Fi and so on, the main purpose of inventing this Zigbee Wireless Sensor Network is that it would more Power efficient, Cost efficient, reliable and can send the data's quickly from one place to another when compared to the other devices, and it also avoids collision. To send the small packets or data's from one device to another this Zigbee Wireless Sensor Network can be used so that it will be efficient in all the ways.
Various authors and writers have made study about the Zigbee Wireless Sensor Network and have also designed some models to be implemented in the real life. People has used and made research about the Zigbee for using in various places such as houses, industries, medical fields, agriculture, monitoring the plant physiology and the greenhouse and so on. They have tested the models and few people have also implemented in the real life scenarios. And they have proved that it is a more effective Wireless Sensor Network. But like the other Wireless devices, Zigbee is not been used commonly in the real life. So if the people start using it in the real life it will be more effective to the people in all fields and it can also be used at home.
Most of the writers have only compared the Zigbee Wireless Sensor Network with other devices and have written its advantages. Only a very few disadvantages has been stated by the people such as the excess data and storing the information, network latency and if the routers face any problems then all the other nodes connected to it will be affected. But all these problems can be rectified and solved in the future. But people will come to know the disadvantages only after the Zigbee Wireless Sensor Networks are started using in the real life, and the problem can be solved in the future. But as not much people have talked about the disadvantages in their papers, if the Zigbee Wireless Sensor Network does not have any and that will be a great news and then it will become very popular and highly used when compared to the other Wireless networks or devices. So the people should start using this Zigbee Wireless Sensor Networks widely and so we will come to know if any other improvement has to be made to the existing device.
