26-03-2012, 04:42 PM
Overview of HiperLAN
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Wireless LAN Standards
There are 3 different standardizing organizations:
1.IEEE (Institute of Electrical and Electronics Engineers Inc.)
IEEE 802.11 for Wireless LAN
Standards for both 2.4 GHz and 5 GHz band
Most widely used Wireless LAN standard
2.ETSI (European Telecommunication Standards Institute)
ETSI HiperLAN 1 and 2
Standards only for 5 GHz band
3.MMAC (Mobil Multimedia Access Communications)
HiperLAN/2 Standard
A new standard developed by the ETSI Project BRAN for wireless access
to very high rate IP and multimedia applications
Radio sub-system specifications (physical layer, data link layer and convergence layer)
Interoperability standard
Conformance test specifications
Business and Home applications
Globally available
PHY is aligned with IEEE 802.11a
The Basic specification was ready in 1999
Support of Business functions
The Extensions, including 1394 support was ready in 2000
Support of Home specific applications
Most sophisticated (& technically challenging) wireless LAN technology so far defined
Uses a new type of radio technology called Orthogonal Frequency Division Multiplexing (OFDM)
MAC in Different WLAN standards
IEEE 802.11a uses a distributed MAC based on CSMA/CA (Carrier Sense MultiAccess with Collision Avoidance)
HiperLAN/2 (from ETSI) uses a central and scheduled MAC based wireless asynchronous transfer mode (ATM)
MMAC supports both of them.