HIPER LAN (High Performance Radio LAN). Two main standards families for Wireless Lan: IEEE 802.11 (802.11b, 802.11a, 802.11g...) ETSI Hiperlan (Hiperlan Type 1, Type 2, HiperAccess, HiperLink...) HiperLAN Family. Motivation of HiperLAN Massive Growth in wireless and mobile communications
HiperLAN Type 1 Reference Model
HiperLAN Type 2 Reference Model
MAC: Medium Access Sublayer EC: Error Control
CAC: Channel Access Control Sublayer RLC: Radio Link Control
PHY: Physical Layer RRC: Radio Resource Control
DLC: Data Link Control Layer ACF: Association Control Function
CL: Convergence Layer DCC: DLC Connection Control
Each MAC frame is further sub-divided into four phases with variable boundaries:
Broadcast phase: The AP of a cell broadcasts the content of the current frame plus information about the cell (identification, status, resources).
Downlink phase: Transmission of user data from an AP to the MTs.
Uplink phase: Transmission of user data from MTs to an AP.
Random access phase: Capacity requests from already registered MTs and access requests from non-registered MTs.
HiperLAN2 defines six different so-called transport channels for data transfer in the above listed phases. These transport channels describe the basic message format within a MAC frame.
Access feedback channel (ACH): This channel gives feedback to MTs regarding the random access during the RCH of the previous frame. The length is 9 bytes.
HiperLAN2 supports two different types of CLs: cell-based and packet-based.
cell-based CL expects data packets of fixed size (cells, e.g., ATM cells).
packet-based CL handles packets that are variable in size (e.g., Ethernet )