1.4 History of BWA Technologies

1.4 History of BWA Technologies

1.4.1 Video Distribution: LMDS, MMDS and DVB

The Local Multipoint Distribution Service (LMDS) is a fixed wireless access system specified in the United States by the Digital Audio-Visual Council (Davic), a consortium of video equipment suppliers, network operators and other telecommunication industries. Davic was created in 1993. LMDS is a broadband wireless point-to-multipoint communication technology. Originally designed for wireless digital television transmission, the target applications were then video and Internet in addition to phone.

The standard is rather open and many algorithms used for LMDS are proprietary. Depending on the frequency bandwidth allocated, data rates are of the order of tens of Mb/s in the downlink and Mb/s in the uplink. Link distance can go up to a few km. LMDS operates in the 28 GHz frequency band in the United States. This band is called the LMDS band. Higher frequencies can also be used.

The Multichannel Multipoint Distribution Service (MMDS), also known as wireless cable, is theoretically a BWA technology. It is mainly used as an alternative method of cable television. The MMDS operates on frequencies lower than the LMDS, 2.5 GHz, 2.7 GHz, etc., for lower data rates as channel frequency bandwidths are smaller.

Standardising for digital television started in Europe with the Digital Video Broadcasting (DVB) Project. This standardization was then continued by the European Telecommunications Standard Institute (ETSI). DVB systems distribute data by many mediums: terrestrial television (DVB-T), terrestrial television for handhelds (DVB-H), satellite (DVB-S) and cable (DVB-C). The DVB standards define the physical layer and data link layer of a television distribution system.

Many European countries aim to be fully covered with digital television by around 2010 and to switch off analogue television services by then. DVB will also be used in many places outside Europe, such as India and Australia.

1.4.2 Pre-WiMAX Systems

WiMAX and 802.16 systems will be described in detail in Chapter 2. In this subsection, the pre-WiMAX is introduced. The first version of the IEEE 802.16 standard appeared in 2001. The first complete version was published in 2004. There was evidently a need for wireless broadband much before these dates. Many companies had wireless broadband equipment using proprietary technology since the 1990s and even before. Evidently these products were not interoperable.

With the arrival of the 802.16 standard, many of these products claimed to be based on it. This was again not possible to verify as WiMAX/802.16 interoperability tests and plugfest started in 2006. These products were then known as pre-WiMAX products. Pre-WiMAX equipments were proposed by manufacturers often specialising in broadband wireless. Many of them had important markets in Mexico, Central Europe, China, Lebanon and elsewhere. Device prices were of the order of a few hundred euros. A nonexhaustive list of pre-WiMAX manufacturers contains the following: Airspan, Alvarion, Aperto, Motorola, Navini, NextNet, Proxim, Redline and SR Telecom. Intel and Sequans, among others, provide components.

The performances of pre-WiMAX systems are close to the expected ones of WiMAX, whose products should start to appear from the second part of 2006. Many of the pre-WiMAX equipments were later certified and more are in the process of being certified.