Wireless Networks - Essay Example

1. Wireless Technology Wireless networks are the fastest growing trend in networks - no wires are necessary to make the connection their applicationto mobile computers such as notebook computers and personal digital assistants (PDAs) are the fastest growing segment of the computer industry today. Wireless networks have many uses. A common use is the creation of a portable office. People often want to use their portable electronic equipment to send and receive telephone calls, faxes, and electronic mails, and access remote files and so on from anywhere on land, sea or air. (B) Wireless networks uses three major protocols as described below: Wireless application protocol (WAP) a special protocol that allows mobiles to connect to the internet. Short Messaging Services (SMS) a service of sending text messages of up to 160 characters long to mobile phones. Global System for Mobile (GSM) the most widely used mobile telephone protocol worldwide. (ICMR) 1.1 Radio Frequency Radio frequency is a term that refers to alternating current (AC) having characteristics such that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications. These frequencies cover a significant portion of the electromagnetic radiation spectrum, extending from nine kilohertz (9 kHz),the lowest allocated wireless communications frequency (it's within the range of human hearing), to thousands of gigahertz(GHz). When an RF current is supplied to an antenna, it gives rise to an electromagnetic field that propagates through space. This field is sometimes called an RF field; in less technical jargon it is a "radio wave." Any RF field has a wavelength that is inversely proportional to the frequency. In the atmosphere or in outer space, if f is the frequency in megahertz and sis the wavelength in meters, then s = 300/f The frequency of an RF signal is inversely proportional to the wavelength of the EM field to which it corresponds. At 9 kHz, the free-space wavelength is approximately 33 kilometers (km) or 21 miles (mi). At the highest radio frequencies, the EM wavelengths measure approximately one millimeter (1 mm). As the frequency is increased beyond that of the RF spectrum, EM energy takes the form of infrared (IR), visible, ultraviolet (UV), X rays, and gamma rays. Many types of wireless devices make use of RF fields. Cordless and cellular telephone, radio and television broadcast stations, satellite communications systems, and two-way radio services all operate in the RF spectrum. Some wireless devices operate at IR or visible-light frequencies, whose electromagnetic wavelengths are shorter than those of RF fields. Examples include most television-set remote-control boxes, some cordless computer keyboards and mice, and a few wireless hi-fi stereo headsets. (SearchNetworking.com) 2. Wireless Architecture WAP Architecture is divided into several layers. This is often called the 'WAP Stack'. (Bharadwaj) The technical description of each layer of the wireless architecture is explained below. Wireless Application Environment (WAE) The goal of WAE is to establish an environment that allows users to build applications that can be used over a wide variety of wireless systems that can be implemented efficiently. In the WAP model, WAE would be the application environments that sends and receives requests from the Clients to the Gateway to the Origin Server. WAE is composed of user agents such as browsers, text editors, date book or phonebook. WAE is also composed of scripting, higher-lever programming languages and image formats. WAE uses languages such as WML Script (similar to JavaScript) and WML (similar to HTML). Wireless Session Protocol (WSP) The Wireless Session Protocol is the layer that deals with communication between client and proxy or server. The WSP provides dialog between client and server. Wireless Transaction Protocol (WTP) The Wireless Transaction Protocol, in a simple definition, deals with the transaction of data. WTP handles transactions, re-transmission of data, and with the separation and concatenation of data. This particular protocol has a separate interface that manages and referees the WTP layer and the settings of the handheld device. This management application is known as the WTP Management Entity. Wireless Transport Layer Security (WTLS) The Wireless Transport Layer Security is the layer that handles security of data and validity of data between two communicating to manage, start, and finish security issues between two portable devices. Wireless Data Protocol (WDP) The Wireless Data Protocol acts as the communication layer between the upper level protocols (WTLS, WTP, and WSP), and the bearer services. WDP allows the upper layers to function independently from the wireless network at hand, as long as the WTP layer is specifically set to the settings of the bearer settings. (WAP Forum) 3. Types of Wireless Networks There are two types of data networks- switched circuit and packet Switched circuit is often called "dial-up". A device using a switched circuit network only connects to it when data is to be sent. For example, when dialing an ISP to get on the Internet you are using a switched circuit network. (Shrivastav) A packet network is one where you are connected all the time and only pay for the actual data sent. On a packet network, your data is divided into small packets. Each packet has a destination and source address attached to it. It is like dialing a number each time a packet is sent, but much faster. Packet networks are more efficient for many kinds of data applications and allow for instant communications without the need to establish a (dial up) connection to the network. Nearly all data-only wireless networks are packet networks. In contrast, nearly all voice-only networks are switched circuit. (Corporation) 3.1 Wireless Local Area Networks (LAN) A wireless LAN eliminates or greatly reduces the need for wires and cables. Thus, it becomes much easier to set up, relocate and maintain a LAN. (Wikipedia)LAN radio may either involve a high frequency radio technology similar to digital cellular, or a low frequency radio technology, called spread spectrum. The other wireless LAN technology is called infrared because it uses beams of infrared rays to establish network links between the various LAN components. (ICMR) 3.2 Wireless Metropolitan Area Networks (MAN) A metropolitan area network is a bigger version of a LAN and normally uses similar technology. It evolved primarily to permit LAN's to interconnect across a metropolis or a country. It may cover a group of nearby corporate offices or a city and could be either private or public. A MAN can support both data and voice, and might even be related to the local cable television network. 3.3 Wireless Personal Area Networks (PAN) A WPAN (wireless personal area network) is a personal area network - a network for interconnecting devices centered on an individual person's workspace - in which the connections are wireless. Typically, a wireless personal area network uses some technology that permits communication within about 10 meters - in other words, a very short range. One such technology is Bluetooth, which was used as the basis for a new standard, IEEE 802.15. (computing.com) Bibliography 1. B, DR. Keerti. Professor of Information Systems & Technology Rajyalakshmi. 25 August 2004. 2. Bharadwaj, Prof Rakesh. Professor of IT Rajyalakshmi. 9 June 2006. 3. computing.com, SearchMobile. SearchMobileComputing.com. 25 November 2007 . 4. Corporation, Systems Nettech. Introduction to Wireless Data. 2002. 25 November 2007 . 5. ICMR. Information Technology & Systems. Hyderabad: ICFAI Center for Management Research, 2003. 6. SearchNetworking.com. SearchNetworking.com. 14 July 2000. 25 November 2007 . 7. Shrivastav, Prof. Neha. Professor of Electronic Rajyalakshmi. 12 October 2006. 8. WAP Forum. "Overview of Wireless Architecture & Products." n.d. Read More