The ZigBee Standards for Wireless Applications Essay

Figure 1 23 shows the proposed network arrangement between the nodes and their associated roles within the ZigBee network. The roles within the network are in accordance with the functionalities and requirements of each type of device as specified by the ZigBee networking standard. The PC/base station has been appointed the role of coordinator since its functions include hosting the SLAM and GUI processes. Therefore the PC/base station is required to transmit GUI data commands and receive updated sensor data to and from both quadcopters. Furthermore as these processes are computationally intensive and require a lot of memory resource; the PC/ base station must be mains powered; reinforcing the requirement for it to be a coordinator. The quadcopters have been appointed the role of routers so that they are able to relay data intended for the coordinator between each other, if one of the quadcopters should fall beyond the range of the coordinator. This would not have been possible if they were appointed the role of end devices. The quadcopters will be battery powered although the ZigBee standard for routers recommend that they be mains powered. Nevertheless, this recommendation was made out of preventing different network segments from falling if power to the router is lost. However this is not applicable in terms of this project as the routers will not be connected to any other network segments.

The other wireless techniques such as Bluetooth, infrared etc are having the limitations of range and also of the efficiency. The wireless system based on GSM/GPRS is well known. But the fee is needed of using GSM/GPRS network, and also the cost of hardware system is very high. The following are the some of the features of the zigbee

1. Describe the 7 layer OSI model of communication layers? Discuss Each Layer in detail.

- Allowing application processes to register unique process addresses. It provides the means by which these process addresses can be resolved to the network-layer or data-link-layer NIC addresses, if necessary.

802.11 are just digits for someone from outside wireless but for people interested in wireless technologies they have a significant value. Institute for Electrical and Electronics Engineers (IEEE) sets up certain standards for researching technologies in certain fields. 802 is such standard which deals with Local area networks and Metropolitan area networks. 802.11 is the standard dealing with implementation of Wireless-LAN.

Wireless networks serve as the transport mechanism between devices and among devices and the traditional wired networks (enterprise networks and the Internet). Wireless networks are many and diverse but are frequently categorized into three groups based on their coverage range: Wireless Wide Area Networks (WWAN), Wireless Local Area Network (WLANs), Wireless Personal Area Network (WPAN )and etc.

ZigBee uses 128 bit AES encryption algorithms for a highly secure network. In commercial or industrial settings, hackers might try to perform a Denial of Lighting, similar to a Denial of Service on internet sites that they hack into. This might not be done only to be disruptive, but on large buildings in major cities, hackers might be tempted to black out only some lights in order to spell words or slogans with the remaining lights. Triggering fire alarms could also be an effective way to get a target out of a building and in the open in an assassination attempt. Access control through wireless connections might lead to break-ins and burglary in an insecure environment. For these reasons ZigBee has been designed to have a high level of security.

The research project is aimed at studying ways in which this new technology is helpful for day-to-day communication needs. It focusses on the potential benefits that can be reaped by following this standard for wireless connectivity. The cons related to it need to be understood thoroughly so that it can be improved in its coming versions so that we may progress more in the wireless communication domain. Since it is based upon Layer 1 and part of layer 2 OSI Model, it may prove further useful to connect a number of devices.

2.1. Physical Layer (PHY) IEEE 802.15.4 offers three operational frequency bands: 2.4 GHz, 915 MHz and 868 MHz. There is a single channel between 868 and 868.6 MHz, 10 channels between 902 and 928 MHz, and 16 channels between 2.4 and 2.4835 GHz. The data rates are 250 kbps at 2.4 GHz, 40 kbps at 915 MHZ and 20 kbps at 868 MHz. Lower frequencies are more suitable for longer transmission ranges due to lower propagation losses. However, the advantage of high data

Bridges connect network of similar protocols thus allowing communication between them. They operate on the second (data link) layer of the open system interconnection (OSI) model. The data link layer frames messages for transmission, establishes and error free communication path, ensures sequence of transmitted data, manages access on channel use and check integrity of received messages.

In these modern times when communication has become a fundamental tool for progress and advancement on many terms, it is already considered an imperative for many companies and businesses to improve their communication and information technology. The advent of new technologies and the introduction of newer softwares and tools necessary for survival in the tough and competitive market make it possible for many businesses and companies to reach their employees, other partner markets or businesses and even their customers while on the move. This is the gift of wireless devices and applications technology.

G.9959 is a MAC layer protocol from ITU, designed for low bandwidth and cost, half-duplex reliable wireless communication. [30]

There has been tremendous growth in wireless network over the last few decades. Wireless devices such as mobiles, laptops are increasing day by day; hence there is requirement of more frequency bands. The need of allotting different frequencies is due to fact that there should not be any interference. Interference is caused when two applications are using the same frequency band. In wireless network data is propagated in the form of electromagnetic

So, this layer moves entire frames from one network element to adjacent one and the service provided by link layer is protocol dependent.

A wireless sensor network (WSN) is a network consisting of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, humidity, motion or pollutants and to cooperatively pass their data through the network to a main location. The WSN is built of nodes from a few to several hundreds or even thousands, where each node is connected to one (or sometimes several) sensors. Each such sensor network node has typically several parts: a radio transceiver with an internal antenna or connection to an external antenna, a microcontroller, an electronic circuit for interfacing with the sensors and an energy source, usually a battery or an embedded form of energy harvesting [23].