WiMAX at 4.9 GHz for disaster relief

The band 4940-4990 MHz has been identified by the ITU as important in achieving harmonised spectrum for advanced public protection and disaster relief. The band is currently used for this purpose in the US.

In Australia the band is officially designated for Department of Defence uses, however ACMA has stated that, "the band will not be available for general WAS use as it will be limited to government PPDR agencies and there will be a requirement to determine sharing arrangements and coordinate with Defence before use."

Reserved PPDR spectrum allows the use of relatively high power levels and provides security and protection from interference for users.

However, the operation of WiMAX (IEEE802.16) equipment in the 4.9 GHz band provides a fast, secure and spectrally-efficient wireless network connection. It also has the following advantages.

Capacity: Each 10 MHz channel offers ethernet speeds of up to 27 Mbps. Spectrum allocation allows five channels, allowing radio-planning for coverage and capacity. GPS synchronisation allows co-location of all sectors.

Coverage: Point-to-multipoint operation with high-gain antennas allow network connections over tens of kilometres.

Security: Highly secure encryption and authentication schemes <0x2014> AES/DES and in-built X.509 certificates.

QOS: Allows managed sharing by varied users and applications <0x2014> for example: guaranteed quality of VoIP across a connection shared by other users <0x2019> traffic.

Reliability: Rugged, portable outdoor receivers. Weatherproof housings.

Ad hoc installation: Lightweight, low-power base stations and receivers can operate with only a 10-52 VDC input. No equipment racks are required; the units can be deployed in minutes.

It is available any time when a fast network connectivity is required at the coal-face. Increasingly, all kinds of tools rely on having an IP network transport and the demand for speed is always increasing.

These are examples of the versatility of the band.

CCTV surveillance: Fixed or temporary installations, the primary requirement is for sufficient uplink bandwidth to return video streams in real time with high image quality.

Mobile command post: Mobile incident-response units require a high-speed, secure, back-to-base network connection. This must be capable of quick deployment in the field without specialist training.

Ad hoc incident-area connectivity: Wi-Fi hotspots can be deployed wherever they are needed, when WiMAX backhaul is used. WiMAX receivers with integrated Wi-Fi access points can be placed outdoors around an incident area and only AC or DC power is required.

Remote medical diagnosis: Medical images and video can be transmitted from the field for remote real-time analysis, allowing faster and more accurate decisions about how to transport patients and to which facility.

Example: Airspan, in association with Intel, installed a WiMAX wireless broadband system at the 2006 Melbourne Grand Prix. This system provided X-ray images from temporary trackside medical facilities, directly to the Alfred Hospital trauma centre for immediate interpretation.

Now this is not just all theory. My company, Airspan Networks, has deployed a large 4.9 GHz WiMAX system in Tokyo.

Although this spectrum is not used for PPDR in Japan, this large-scale project has verified some key concepts:

• 'Re-banding' of the WiMAX Forum 5.8 GHz profile
• Outdoor Airspan WiMAX receiver units with integrated Wi-Fi hotspots
• Centralised management of the wireless network
• Coverage and capacity

About the author: Grant Stepa has over 23 years IT&T industry experience including 14 years in senior management roles. He has over 20 years' experience in communications specialising in wireless. His past practical experience covers software and hardware design, telemetry and radio systems design including wireless networks and hands on implementation. He has worked extensively throughout Asia with a past focus on China and Taiwan, developing markets in wireless data communications. He established Airspan's subsidiary office in Australia in 2000 and as MD has been responsible for the rapid growth in deployments of Airspan's Carrier Class voice and data PMP and PTP systems (including WiMAX).