Zigbee Networks and Specifications - Case Study Example

Zigbee Networks and Specifications It would not be wrong to term the current times as the technological era since humans are surrounded by machines and gadgets. The abundance of technological inventions in the environment generates the desire to control all of them with a centralized mechanism. Researchers have been working on the development of wireless technologies for the automation of homes and different establishments since many years. It is due to the increasing desire of automation that Zigbee Alliance introduced Zigbee protocol in the domain of wireless sensor networks. Zigbee is a set of specifications that facilitate a low cost, low consumption power, low data transfer load and non-complex wireless mesh network. Zigbee protocol has been standardized by IEEE. In this paper, the basic attributes of Zigbee networks shall be discussed along with the network topologies, applications and components. The protocol shall also be studied with reference to the OSI model to highlight the layers where it is defined. Table of Contents Abstract ii List of Figures iv 1. Introduction 1 2. Background 1 3. Components of Zigbee Networks 3 4. Applications of Zigbee 5 5. Network Topologies of Zigbee Networks 5 6. Zigbee Specifications in OSI Model 7 7. Conclusion 8 References 9 List of Figures Figure 1: Zigbee comparison with other wireless technologies 2 Figure 2: Zigbee network in a smart home 3 Figure 3: Coordinator, Router and end-devices 4 Figure 4: Types of network topologies of Zigbee standard 6 Figure 5: OSI layers comparison with the definition of Zigbee in the model 7 Zigbee Networks and Specifications 1. Introduction Technology has intervened to an extensive degree in the lives of humans. The intervention has made man rely on technology for his business, as well as domestic needs. The trend of transforming regular houses into smart homes has been a field of interest for researchers around the world. Gohn (2007) stated that the advancement in the domain of wireless networking and information technology has made an age-old dream come true of automating one’s house with a centralized source of control. The innovative technology that is responsible for leaping wireless technology to another level of automation is known as Zigbee. The report focuses on the components and network topologies that develop the standard and facilitate communication with devices that are placed within a close range. Section 2 discusses the background and overview of the Zigbee standard. Section 3 includes the components of a Zigbee network while Section 4 discusses the applications of the respective standard. Section 5 includes the network topologies that are followed by the standard and Section 6 defines its placement in the OSI model. 2. Background Several technologies have been developed in the past years that are based on different levels of bandwidth, ranges and degrees of power consumption. Some of the common technologies to provide connectivity with different devices around a smart home have been Bluetooth, Wi-Fi, and WiMax. Leopold, Dydensborg and Bonnet (2003) provided the information that bluetooth is considered to be the first technology in the domain of Wireless Personal Area Network (WPAN) that gained extensive recognition and acceptance. Leopold, Dydensborg and Bonnet (2003) stated that Bluetooth offered omni-directional communication that led to the desire for a smarter technology after some years of its common usage. Stevanovic (2007) provided the information that Zigbee Alliance introduced a new standard with the name ‘Zigbee’. Zigbee is a standard which is meant for communication between embedded devices placed in a limited range. It was recognized as a standard under IEEE 802.15.4. Gohn (2007) stated that the main aim behind the standard was to facilitate wireless connectivity between devices such that it would possess the following attributes: Low complexity Low cost Low consumption of power Two-way communication Low load of data transfer Lönn and Olsson (2005) pointed out that this standard is considered to be included in the domain of Wireless Sensor Networks. The following figure highlights the low range and low load of data transfer in Zigbee as compared to other WPAN technologies: Figure 1: Zigbee comparison with other wireless technologies (Stevanovic, 2007) Lönn and Olsson (2005) stated that the inspiration of the standard was acquired from the mechanism that is followed by bees to communicate; a zigzag dance is done by them to transfer relevant messages to each other. In the same manner, Zigbee standard aims to form a network between isolated and simple devices to make them perform non-complex operations. The following figure shows the layout of a smart home where all the devices are connected to each other and forming a Zigbee network: Figure 2: Zigbee network in a smart home (Gohn, 2007) Such level of centralized automation eradicates the need to maintain multiple remotes and controlling devices. 3. Components of Zigbee Networks The network is mainly based on three types of devices: Coordinator: Gohn (2007) stated that coordinator is the node that initiates communication, configures and controls the other nodes in the network. This node is meant to possess information regarding the other devices in the network therefore it is known to have greater computing and storage capabilities. Information in the coordinator may also include security keys for communication between the nodes and list of network addresses. Router: Routers expand the network coverage and facilitates communication between end-devices and the coordinator. Daintree Networks (2010) stated that unforeseen instances like network congestion are tackled by routers. Routers are capable of supporting child devices. End Devices: End devices are the appliances and gadgets present in the environment that are meant to be controlled by means of the coordinator. Daintree Networks (2010) stated that these devices are capable of sending and receiving messages but are not equipped to carry out routing tasks; it is due to this reason that they are dependent on routers or coordinators for communication within the network. They are also not capable of supporting other end devices. The following figure shows all the types of devices in a Zigbee network: Figure 3: Coordinator, Router and end-devices (Daintree Networks, 2010) 4. Applications of Zigbee Zigbee standard has numerous applications since there is an increasing need of automation and centralized control in the prevailing technological era. Some of the applications have been given by Daintree Networks (2010), they are as follows: Home automation: Home appliances, gadgets and entertainment devices can be automated effectively thereby giving the owner a centralized level of control on all devices. Other household mechanisms like cooling, security, heating and lighting can also be incorporated in the network. Office Automation: Centralized power facilitates effective management and control of usage; such control will benefit an organization if they opt for implementing the Zigbee standard to centralize their cooling, heating, security and lighting mechanisms in their establishments. Lönn and Olsson (2005) provided the information that Zigbee Alliance, a group of association companies, works together to promote compatibility, flexibility and reliability in devices that have low power consumption and computing needs. They follow an open global standard that facilitates the production of wireless and compatible devices. Gohn (2007) stated that such endeavors increase the application of Zigbee standard since more devices become compatible with each other. 5. Network Topologies of Zigbee Networks ICP DAS USA (n.d.) stated that Zigbee mesh networks are known to be self-healing and self-configuring. ICP DAS USA (n.d.) also provided the information that Zigbee standard specifies three types of network topologies; star, mesh and cluster networks. The following figure shows the arrangement of the three types of devices in each of these network topologies: Figure 4: Types of network topologies of Zigbee standard (ICP DAS USA, n.d.) Star Network: Star networks are usually applied in home networks since they are directly controlled by means of a coordinator (via an intermediate router). Craig (n.d) provided the information that star networks facilitate longer battery life. Failure or crash of any router or node will not disturb the connectivity of other nodes. Mesh Network: Daintree Networks (2010) stated that mesh network provides higher level of reliability since there exists multiple paths for any node. Failure of any single node might cease path for other nodes as well, thereby compelling them to adopt different path for successful communication. Cluster Network: Craig (n.d) stated that this topology is a hybrid topology of star and mesh network, thereby providing greater reliability and longer battery life. According to Benakila, Femmam and George (2010), Zigbee standard can function on any of the following frequency bands; 2.4 GHz, 915 MHz and 816 MHz. Gohn (2007) provided the information that channel access mechanism followed by Zigbee is CSMA-CS, while the range limit is 10 to 20 m. 6. Zigbee Specifications in OSI Model Lönn and Olsson (2005) explained that Open System Interconnection (OSI) model is the generic framework that is meant to develop protocol standards. The standard 7 layers of OSI model have been shown below to identify the layers where Zigbee has been defined: Figure 5: OSI layers comparison with the definition of Zigbee in the model (Lönn and Olsson, 2005) Galeev (2004) stated that 802.15.4 standard should be understood as the physical radio while Zigbee should be perceived as the logical network to comprehend the model. Physical and Medium Access Control (MAC) layer are defined by 802.15.4 standard whereas the other top layers are defined by Zigbee Alliance. 7. Conclusion Zigbee is a set of specifications that has been recognized by IEEE as 802.15.4 standard. Zigbee is defined as a low computing power and consumption power wireless mesh network, coupled with non-complex functions and low data transfer loads. There are three types of devices present in the network that make communication possible amongst all the participating nodes; coordinator (controlling the network), router (serving as an intermediate node) and end-devices (devices that can only send or receive messages). Such networks and standards are being increasingly used to automate houses and offices since they give a centralized power to all the participating devices. Zigbee standard follows three types of network topologies; star, cluster and mesh networks. With reference to the OSI model, two lowest layers (physical and medium access layer) are specified by IEEE 802.15.4 and the above layers are specified by Zigbee specifications. Zigbee protocol is no less than a leap into the future of smart homes where all the controls are automated by a single source of authority and control. References: Benakila, I., Femmam, S., & George, L. (2010). Designing a ZigBee Network for Signal Perception. European Journal of Scientific Research, 40(2), 264-278. Craig, W. C. (n.d.). Zigbee: Wireless Control That Simply Works, ZMD America, Inc. Retrieved October 20, 2011, from https://docs.zigbee.org/zigbee-docs/dcn/04-1427.pdf Daintree Networks, (2010). Getting Started with ZigBee and IEEE 802.15.4. Retrieved October 15, 2011, from http://www.daintree.net/downloads/whitepapers/zigbee_primer.pdf Galeev, M. (2004, April 4), Home networking with Zigbee, EETimes, Retrieved from http://www.eetimes.com/design/embedded/4006430/Home-networking-with-Zigbee Gohn, B. (2007). Appliance Design. Zigbee Zings. Retrieved October 22, 2011, from http://www.ember.com/pdf/DesignMagazineReprint.pdf ICP DAS USA, (n.d.). Zigbee- Free as a bee!. Retrieved October 13, 2011, from http://www.icpdas-usa.com/documentation/Quickstarts/ZigBee_icp.pdf Lönn, J., & Olsson, J. (2005). ZigBee for wireless networking, (Master Thesis). Linköping University. Leopold, M., Dydensborg, M. B. & Bonnet, P. (2003), Bluetooth and Sensor Networks: A Reality Check, SenSys’03: proceedings of the First International Conference on Embedded Networked Sensor Systems, November 5-7, Los Angeles. Stevanovic, D. (2007). Zigbee / IEEE 802.15.4 Standard, [PowerPoint slides], York University, Retrieved from http://www.cse.yorku.ca/~dusan/Zigbee-Standard-Talk.pdf. Read More