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HIPER LAN (High Performance Radio LAN)

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

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HIPER LAN (High Performance Radio LAN)

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  1. HIPER LAN(High Performance Radio LAN)

  2. 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

  3. Motivation of HiperLAN • Massive Growth in wireless and mobile communications • Emergence of multimedia applications • Demands for high-speed Internet access • Deregulation of the telecommunications industry

  4. The History, Present and Future • HiperLAN Type 1 • Developed by ETSI during 1991 to 1996 • Goal: to achieve higher data rate than IEEE 802.11 data rates: 1~2 Mbps, and to be used in ad hoc networking of portable devices • Support asynchronous data transfer, carrier-sense multiple access multiple access with collision avoidance (CSMA/CA), no QoS guaranteed.

  5. HiperLAN Type 2 • Goal: Providing high-speed (raw bit rate ~54Mbps) communications access to different broadband core networks and moving terminals • Features: connection-oriented, QoS guaranteed, security mechanism, highly flexibility • HiperAccess and HiperLink • In parallel to developing the HIPERLAN Type 2 standards, ETSI BRAN has started work on standards complementary to HIPERLAN Type 2

  6. Architecture Control Plane User Plane CL MAC RRC ACF DCC EC CAC RLC MAC PHY DLC HiperLAN Type 1 Reference Model PHY 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

  7. CAC: Channel Access Control Sublayer • This sub layer deals with the access request to the channels. • The accomplishing of the request is dependent on the usage of the channel and the priority request.

  8. HIPERLAN2 Protocol Stack

  9. DLC: MAC Sublayer • The medium access control creates frames of 2 ms duration as shown in Figure. With a constant symbol length of four μs this results in 500 OFDM symbols.

  10. 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.

  11. 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. • Broadcast channel (BCH): This channel conveys basic information for the radio cell to all MTs. This comprises the identification and current transmission power of the AP. The length is 15 bytes. • Frame channel (FCH): This channel contains a directory of the downlink and uplink phases (LCHs, SCHs, and empty parts). This also comprises the PHY mode used. The length is a multiple of 27 bytes.

  12. 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. • Long transport channel (LCH): This channel transports user and control data for downlinks and uplinks. The length is 54 bytes. • Short transport channel (SCH): This channel transports control data for downlinks and uplinks. The length is 9 bytes. • Random channel (RCH): This channel is needed to give an MT the opportunity to send information to the AP/CC even without a granted SCH. The length is 9 bytes.

  13. DLC: Error Control • Acknowledged mode: selective-repeat ARQ • Repetition mode: typically used for broadcast • Unacknowledged mode: unreliable, low latency • DLC: other features • Radio network functions: Dynamic frequency selection; handover; link adaptation; multibeam antennas; power control • QoS support: Appropriate error control mode selected; Scheduling performed at MAC level; link adaptation; internal functions (admission, congestion control, and dropping mechanisms) for avoiding overload

  14. Radio Link Control Sublayer • It offers connection oriented systems ,offering QoS. • Three main control functions • Association control function (ACF): authentication, key management, association, disassociation, encryption • Radio resource control function (RRC): handover, dynamic frequency selection, mobile terminal alive/absent, power saving, power control • DLC user connection control function (DCC): setup and release of user connections, multicast and broadcast

  15. Convergence Layer 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 )

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