HiperLAN

HiperLAN is a European family of standards on digital high-speed wireless communication in the 5, 15-5, 3GHZ and the 17.1-17.3GHZ spectrum. The committee responsible for HiperLAN is RES-10 which has been working on the standard since November 1991.

The standard serves to ensure the possible interoperability of different manufacturers' wireless communications equipment that operate in this spectrum. The HiperLAN standard only describes a common air interface including the physical layer for wireless communications equipment, while leaving decisions on higher-level configurations and functions open to the equipment manufacturers.

The choice of frequencies allocated to HiperLAN was part of the 5-5,30GHz band being allocated globally to aviation purposes. The Aviation industry only used the 5-5,15GHz frequency, thus making the 5,15-5,30 frequency band accessible to HiperLAN standards.

HiperLAN is designed to work without any infrastructure. Two stations may exchange data directly, without any interaction from a wired (or radio-based) infrastructure.

The simplest HiperLAN thus consists of two stations. Further, if two HiperLAN stations are not in radio contact with each other, they may use a third station (i.e. the third station must relay messages between the two communicating stations).

Products compliant to the HiperLAN 5 GHZ standards shall be possible to implement on a PCMCIA Type III card. Thus the standard will enable users to truly take computing power on the road. The HiperLAN standard has been developed at the same time as the development of the Supernet standard in the United States.

Requirements for HiperLAN

• Short range - 50m
• Low mobility - 1.4m/s
• Networks with and without infrastructure
• Support asynchronous traffic
• Audio 32kbps, 10ns latency
• Video 2Mbps, 100ns latency
• Support asynchronous traffic
• Data 10Mbps, immediate access

Ad-Hoc Capabilities of HiperLAN

Among other technologies HiperLAN will offer high data rates and relative high throughput even without any infrastructure in the network. This opens basically new applications to wireless data communications. Compared to the growth in for example the number of Internet nodes, which has risen from virtually nothing in 1986 to over 1.4 Millions in 1993, the potential number of HiperLAN nodes is even higher. Radio-based LANs are doing to portables what they should be: truly movable.

Quality of Service (QoS) in HiperLAN

Performance is one of the most important factors when dealing with wireless LANs. In contrast to other radio-based systems, data traffic on a local area network has a randomized bursty nature, which may cause serious problems with respect to throughput. Many factors have to be taken into consideration, when quality of service is to be measured. Among these are:

• The topography of the landscape in general
• Elevations in the landscape that might cause shadows, where connectivity is unstable or impossible.
• Environments with many signal-reflection surfaces
• Environments with many signal-absorbing surfaces
• Quality of the wireless equipment
• Placement of the wireless equipment
• Number of stations
• Proximity to installations that generate electronic noise
• and many more

The sheer number of factors to take into consideration means, that the physical environment will always be a factor in trying to asses the usefulness of using a wireless technology like HiperLAN. Simulations show that the HiperLAN MAC can simultaneously support:

• 25 audio links at 32kbit/s, 10ms delivery
• 25 audio links at 16kbit/s, 20ms delivery
• 1 video link at 2Mbit/s, 100ms delivery
• Asynchronous file transfer at 13.4Mbit/s

The future of HiperLAN

A new set of standards are under construction for a new version of HiperLAN named as 'HIPERLAN2'. The idea of HIPERLAN2 is to be compatible with ATM.

From the perspective of the data communications industry, HiperLAN is the most interesting of the coming standardized wireless technologies. HiperLAN has the highest data rate, and its design allows for a variety of applications. The tentative design parameters for HiperLAN were:

Parameter	Traffic Type	Value
Data rate	Asynchronous	1 to 20 Mbit/s
	time-bounded	64 kbit/s to 2.048 kbit/s
Systems throughput		20 Mbit/s 1000 Mbit/s per hectare per floor
Mean latency	Asynchronous	<1 ms. (at 30% capacity
Latency of service initiation	time-bounded	<3 S
MSDU Delay variance	asynchronous	no limit
	time-bounded	<3.0 mS2
Range		to 50 m at 20 Mbit/s to 800 m at 1 Mbit/s
Area Coverage		99.9% (single hop)
Temporal Coverage		99.9% (single hop)
MPDU detected loss/error rate		<10-3
MPDU undetected loss/error rate		<8x10-8 per octet pf MPDU length
MSDU undetected loss/error rate		<5x10-14 per octet of MPDU length
Co-location tolerance		50 cm of free space
Mobility tolerance		10 m/s linear, 360o/s angular
Packet information field maximum size		16 Kbytes
Physical size target (excl. antenna system)		PC-Card (PCMCIA) type III (85x54x10.5 mm)
Power consumption		few hundred mW