Fixed broadband radio access

Abstract

The need for broadband residential access is growing. Among the different access systems, radio systems can provide an economical means of realising a broadband last mile solution.

The frequencies available for a broadband radio system are very high, 27 GHz and 42 GHz. A system operating at these frequencies has a strict LOS restriction. This means that every residence in a certain area cannot be guaranteed availability of the service. The rain attenuation is also significant at these frequencies.

Beyond the well known multiple access methods FDMA, TDMA and CDMA, new multiple access methods have been suggested for broadband systems. Especially TDMA with adaptive modulation schemes and MC-CDMA systems are proposed.

When discussing broadband wireless communication, ATM has gained much popularity as the platform on which the broadband services can be transported. Wireless ATM is standardised by the ATM Forum. QoS is another important aspect of ATM. Real time broadband services have strict QoS requirements and ATM can guarantee QoS.

To date the only available specification on fixed broadband radio access is the specification made by DAVIC. Other standardisation bodies such as ETSI project BRAN is working on a standard for fixed broadband radio access, this project is scheduled to finish in 2005. The DAVIC standard specifies the lower layer protocols and physical interfaces. Downstream communication is based on ATM or MPEG-2 transport streams and upstream communication is based on ATM transport stream.

The competing technologies that offer a solution to the broadband last mile problem are LMDS, xDSL, cable modems, and satellite. The advantages of LMDS are the possibility of rapid deployment, small initial cost, two way capability, and flexibility. LMDS is flexible to build out and to reconfigure.