Wireless Local Area Network WLAN and Wi-Fi

42 extensive variety of multimedia services at a slow speed up to 114 Kbps. The type of services is legislated by an Access Point Name APN which de fine services for example Wireless Ap- plication Protocol WAP access, Multimedia Messaging Ser- vice MMS, Short Message Service SMS, Point-to-focus PTP and Internet access. 3 G 1.8 Ghz: Third Generation technology that is an im- provement on the earlier 2.5 G version and has a maximum speed of 14.4 Mbps. The main characteristics of 3G are mobile TV broad casting and video calling. There are diverse interface networking systems that are accepted by the ITU International Telecommunications Union IMT-2000 as 3 G networks. The prominent ones are Mobile WiMAX and UMTS Universal Mobile Telecommunications System that is otherwise called W-CDMA where W signifies Wideband. The Mobile WiMAX is named under Worldwide Interoperability for Microwave Ac- cess and is developed from the IEEE 802.16 Broadband Wire- less Access BWA standard. UMTS is a substantially more developed and generally used technology and is an immediate upgrading of 2.5 G that basically developed from previous ac- cessible mobile technologies. An enhanced adaptation generally denoted as 3.5 G was introduced in 2006 as High Speed Down- link Packet Access HSDPA which can support over 20 Mbps. In the year 2012, this is expected to be upgraded to 4 G with 100 Mbps and upgraded security features. In between the 2.5 G and 3 G version there is a technology frequently known as 2.75 G. Although, this version is not regularly used but most people are familiar with CDMA2000 and EDGE Enhanced Data rates for GSM Evolution. These are developed from CDMA1900 and GSM Phase 2+. However, these versions are often wrongly categories as 3 G because their expanded information capaci- ties supports 2.5 G systems. 43 PHS 1.9 Ghz: Personal Hand phone System is popularly used in Japan only because of its low power usage and does not re- quire a SIM card. The system is primarily intended for its voice calls with data support until 256 Kbps. Nevertheless, PHS is gradually being phrase out by 3 G networks.

2.2.6 Broadband Wireless Access BWA

BWA can support a wide range of services because of its ultra- high speed. Generally BWA is adopted for medium to long range distribution and the carrier frequency can vary between couples of Ghz to 40 Ghz based on local bylaws. The develop- ment of BWA is legislated by the IEEE 802.16 Working Group on Broadband Wireless Access Standards. However, IEEE 802.16 does determine the prerequisites of frequency bands or certification of equipment. Fixed or portable WiMAX operating at 2.4 to 5 Ghz ISM band is compatible with both IEEE 802.16e and ETSI HiperMAN wireless. A metropolitan Area Network MAN principle which covers several kilometers is gaining popularity as of late because of its high level of interoperability. Local Multipoint Distribution Service LMDS which is a common BWA operation is used for fixed networking which implies that mobility support is very constrained. The major dis- tinction between MNDS and Fixed WiMAX is the operating frequency which paves the way to a signi ficant enhancement in channel bandwidth. LMDS is able to support over 512 Mbps for transmitting large amounts of data. Since the radios possess a 90 ˚ field of view, it is practical to utilize four radios for omnidi- rectional 360 ˚ coverage. The features of LMDS make it espe- cially suitable for telemedicine backbone support. The expression backbone denotes the medium which accommo- dates a major trunk line for interconnecting an array of local area networks LANs and also equipment over a vast area. For instance, an organization such as a hospital may have numerous