The ZigBee Standards for Wireless Applications Essay

Layer 3 is the network layer and utilises multiple common protocols to perform routing on the network. Protocols consist of the Internet Protocol (IP), packet sniffing and DoS attacks such as Ping floods and ICMP attacks. Because of their layer 3 nature, these types of attacks can be performed remotely over the Internet while layer 2 attacks primarily come from the internal LAN.

The OSI Model is a model is used to define how data is theoretically passed on a network. Each layer is responsible and has its own duties for a network. The name of layer 3 in the OSI is the Network Layer. This layer is responsible for creating the paths for the transmission of data across the network. This layer provides routing and switching capabilities, as well as, internetworking, congestion control, and packet sequencing (Beal, 1999).

The fifth layer is the session layer this establishes a connection,this layer makes and sets up the connection using co ordinates and could terminate conversations links. the session layer produces services that make authentication after an interruption and not only that but it can reconnect.and as well as the transporting layer it can also have the TCP and the UDP can provide services for all most all applications.An application layer is an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communications network. The application layer abstraction is used in both of the standard models of computer networking; the Internet Protocol Suite (TCP/IP) and the Open Systems Interconnection model (OSI model).Although both models use the same term for their respective highest level layer, the detailed definitions and purposes are different.In TCP/IP, the application layer contains the communications protocols and interface methods used in process-to-process communications

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.

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

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.

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

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.

For a reliable network layer a minimal transport layer is required. Functions of the transport layer include the following.

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

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.

In order for ZigBee to catch on in businesses and homes it needs to be simple to set up the network and to add new devices. ZigBee networks rely on simplicity and ease of setup. In most instances a new device is simply synchronized with the existing network by placing the two devices close together and pressing a button on each device at the same time.

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.

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

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