• 21.11 Other WLAN Standards
  • 21.11.1 HIPERLAN Family of Standards
    		•

      21 Wireless Local Area Networks




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    21 Wireless Local Area Networks
    Because it promises far greater bandwidth, better range, and reliability, 
    802.11n is advantageous in a variety of network confi gurations. And as emerging 
    networking applications take hold in the home, a growing number of consumers 
    will view 802.11n not just as an enhancement to their existing network, but as a 
    necessity. Some of the current and emerging applications that are driving the need 
    for 802.11n are voice over IP (VoIP), streaming video and music, gaming, and 
    network attached storage.
    21.11 Other WLAN Standards
    The high performance radio local area network (HIPERLAN) committee in 
    ETSI, referred to as Radio and Equipment Systems (RES) 10, worked with the 
    European Conference of Postal and Telecommunications Administration (CEPT, 
    a committee of PTT and other administration representatives) to identify its 
    target spectrum. The CEPT identifi ed the 5.15–5.25 GHz band (this allocation 
    allows three channels), with an optional expansion to 5.30 GHz (extension to 
    fi ve channels). Any country in the CEPT area (which covers all of Europe, as 
    well as other countries that implement CEPT recommendations) may decide 
    to implement this recommendation. Most of the CEPT countries permit HIP-
    ERLAN systems to use this 5 GHz band. In the United States, the U.S. Federal 
    Communications Commission (FCC) followed the European model roughly. The 
    unlicensed National
    Information Infrastructure band (U-NII) covers approxi-
    mately 300 MHz in three different bands between 5.1 and 5.8 GHz. The regula-
    tors in Japan are likely to align with the 5 GHz band also. In addition, a second 
    band from 17.1 to 17.3 GHz was identifi ed by CEPT but so far no systems have 
    been defi ned to use this band.
    21.11.1 HIPERLAN Family of Standards
    HIPERLAN/1 is aligned with the IEEE 802 family of standards and is very much 
    like a modern wireless Ethernet. HIPERLAN/1, a standard completed and ratifi ed 
    in 1996, defi nes the operation of the lower portion of the OSI reference model, 
    namely the data link layer and physical layer [9,10]. The data link layer is further 
    divided into two parts, the channel access control (CAC) sublayer and media 
    access control (MAC) sublayer. The CAC sublayer defi nes how a given channel 
    access attempt will be made depending on whether the channel is busy or idle 
    and at what priority level an attempt will be made. The HIPERLAN MAC layer 
    defi nes the various protocols which provide the HIPERLAN/1 features of power 
    conservation, security, and multihop routing (i.e., support for forwarding), as well 
    as the data transfer service to the upper layers of protocols. HIPERLAN/1 uses 
    the same modulation technology that is used in GSM, Gaussian minimum shift 
    keying (GMSK). It has an over air data rate of 23.5 Mbps and maximum user data 
    rate (per channel) of over 18 Mbps. The range in a typical indoor environment 
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    is 35 to 50 meters. HIPERLAN/1 provides quality of service (QoS), which lets 
    critical traffi c be prioritized.
    HIPERLAN/2 has many characteristics of IEEE 802.11 WLAN. HIPER-
    LAN/2 has three basic layers: physical layer (PHY), data link control layer (DLC), 
    and convergence layer (CL) (see Figure 21.18). The protocol stack is divided into a 
    control plane and a user plane. The user plane includes functions for transmission 
    of traffi c over established connections, and the control plane performs functions 
    of connection establishment, release, and supervision. The transmission format 
    on the physical layer is a burst consisting of a preamble part and a data part. The 
    data part originates from each of the transport layers within DLC. A key feature 
    of the physical layer is to provide several modulation and coding schemes accord-
    ing to current radio link quality and meet the requirements for different physical 
    layer modes as defi ned by transport channels within DLC. Table 21.14 provides a 
    comparison of the IEEE 802.11 WLAN with HIPERLAN/2.
    The faster HIPERLANs include the high performance radio access (HIPER-
    ACCESS) and high performance metropolitan area network (HIPERMAN). Both 
    HIPERACCESS and HIPERMAN are designed for broadband speeds and greater 
    ranges than HIPERLAN/2. HIPERACCESS provides up to 100 Mbps in the 40.5–
    43.5 GHz band whereas HIPERMAN is designed for a WMAN in 2 GHz and 
    11 GHz bands.
    The DLC layer constitutes the logical link between an access point (AP) 
    and mobile terminals (MTs). The DLC includes functions for medium access and 
    transmission as well as terminal/user connection handling. The DLC layer consists 
    of medium access control (MAC), error control (EC), radio link control (RLC), 
    DLC connection control (DCC), radio resource control (RRC) and association 
    control function (ACF) (see Figure 21.19). Compared to IEEE 802.11 WLAN, 
    medium access in HIPERLAN/2 is based on the time division duplex/time division 

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