Hyper LAN

Recently, demand for high-speed Internet access is rapidly increasing and a lot of people enjoy broadband wired Internet access services using ADSL ( Asymmetric Digital Subscriber Line) or cable modems at home. On the other hand , the cellular phone is getting very popular and users enjoy its location-free and wire-free services. The cellular phone also enables people to connect their laptop computers to the Internet in location-free and wire-free manners. However ,present cellular systems like GSM (Global System for Mobile communications) can provide much lower data rates compared with those provided by the wired access systems, over a few Mbps(Mega bit per second).Even in the next generation cellular system, UMTS ( Universal Mobile Telecommunications System), the maximum data rate of its initial service is limited up to 384 kbps; therefore even UMTS cannot satisfy users’ expectation of high-speed wireless Internet access. Hence, recently, Mobile Broadband System (MBS) is getting popular and important and wireless LAN (Local Area Network) such as ETSI (European Telecommunication Standardization Institute) standard HIPERLAN (High PErformance Radio Local Area Network) type2 (denoted as H/2) is regarded as a key towards providing high speed wireless access in MBS. H/2 aims at providing high speed multimedia services, security of services , handover when roaming between local and wide area as well as between corporate and public networks. It also aims at providing increased throughput of datacom as well as video streaming applications. It operates in the 5 GHz band with a 100 MHz spectrum. WLAN is W-ATM based and is designed to extend the services of fixed ATM networks to mobile users. H/2 is connection oriented with a connection duration of 2 ms or multiples of that. Connections over the air are time-division multiplexed . H/2 allows interconnection into virtually any type of fixed network technology and can carry Ethernet frames, ATM cells and IP packets. Follows dynamic frequency allocation. Offers bit rates of 54 Mbps.