HiperLAN
From Wikipedia, the free encyclopedia
HiperLAN (HIgh PErformance Radio LAN) is a Wireless LAN standard.[1] It is a European alternative for the IEEE 802.11 standards (the IEEE is an international organization). It is defined by the European Telecommunications Standards Institute (ETSI). In ETSI the standards are defined by the BRAN project (Broadband Radio Access Networks). The HiperLAN standard family has four different versions.
Contents |
[edit] HiperLAN/1
Planning for the first version of the standard, called HiperLAN/1, started 1991, when planning of 802.11 was already going on. The goal of the HiperLAN was the high data rate, higher than 802.11. The standard was approved 1996. The functional specification is EN300652, the rest is in ETS300836.
The standard covers the Physical layer and the Media Access Control part of the Data link layer like 802.11. There is a new sublayer called Channel Access and Control sublayer (CAC). This sublayer deals with the access requests to the channels. The accomplishing of the request is dependent on the usage of the channel and the priority of the request.
CAC layer provides hierarchical independence with Elimination-Yield Non-Preemptive Multiple Access mechanism (EY-NPMA). EY-NPMA codes priority choices and other functions into one variable length radio pulse preceding the packet data. EY-NPMA enables the network to function with few collisions even though there would be a large number of users. Multimedia applications work in HiperLAN because of EY-NPMA priority mechanism. MAC layer defines protocols for routing, security and power saving and provides naturally data transfer to the upper layers.
On the physical layer FSK and GMSK modulations are used in HiperLAN/1.
HiperLAN features:
- range 50 m
- slow mobility (1.4 m/s)
- supports asynchronous and synchronous traffic
- sound 32 kbit/s, 10 ns latency
- video 2 Mbit/s, 100 ns latency
- data 10 Mbit/s
HiperLAN does not conflict with microwave and other kitchen appliances, which are on 2.4GHz.
[edit] HiperLAN/2
HiperLAN/2 functional specification was accomplished February 2000. Version 2 is designed as a fast wireless connection for many kinds of networks. Those are UMTS back bone network, ATM and IP networks. Also it works as a network at home like HiperLAN/1. HiperLAN/2 uses the 5 GHz band and up to 54 Mbit/s data rate.[1]
The physical layer of HiperLAN/2 is very similar to IEEE 802.11a wireless local area networks. However, the media access control (the multiple access protocol) is Dynamic TDMA in HiperLAN/2, while CSMA/CA is used in 802.11a.
Basic services in HiperLAN/2 are data, sound, and video transmission. The emphasis is in the quality of these services (QoS).[1]
The standard covers Physical, Data Link Control and Convergence layers. Convergence layer takes care of service dependent functionality between DLC and Network layer (OSI 3). Convergence sublayers can be used also on the physical layer to connect IP, ATM or UMTS networks. This feature makes HiperLAN/2 suitable for the wireless connection of various networks.
On the physical layer BPSK, QPSK, 16QAM or 64QAM modulations are used.
Good security measures are offered by HiperLAN/2. The data are secured with DES or Triple DES algorithms. The access point and the wireless terminal can authenticate each other.
[edit] HiperLAN
The development of 802.11n standard for Spectrum and Transmit Power Management Extensions, which will define the next level of performance in WLANs, is not paralleled by any further attempt at HiperLAN activity. Some of the principles of HiperLAN/2, for example Dynamic Frequency Selection (DFS), and Transmit Power Control, will be reused in IEEE 802.11n.
Some principles in HiperLAN/2, for example concept of Dynamic TDMA, is used in the broadband wireless access standards such as IEEE 802.16 (WiMax).
