Spectrum-battle hots up
It seems so! Judging from the panel discussions and presentations at the recently held Satcom 2007, the two sectors seem to be on a collision path. Satellite operators use the C-band (C-band uses 3,4 – 4,2 GHz for downlink and 5,925 GHz – 6,425 GHz for uplink) globally to provide essential telecommunication services.
In many countries it serves as the core network for national and international communications and in several African nations it provides the backhaul for cellular services. The satellite operators say they feel threatened by the proponents of WiMAX systems who want to take over part of the C-band. C-band is favoured by satellite operators because of its low susceptibility to interruptions caused by heavy rainfall which is prevalent in higher frequencies
Proposals are now on the table to include IMT services, the global mobile terrestrial standard, within the frequency range 3,4 – 4,2 GHz. The current situation is that the lower end of the frequency range (up to 3,6 GHz) is already identified for use by broadband wireless excess services such as WiMAX.
In countries where WiMAX services already operate on these frequencies, satellite operators are experiencing major interference to their satellite ground stations resulting in service disruption. To make matters worse certain national administrations in Europe and some other parts of the world are now considering identifying the new terrestrial IMT services in the entire 3,4 – 4,2 GHz band.
Some believe that the two services can share the spectrum but satellite won’t buy that as they are already experiencing service disruption. There are methods that can be implemented to make the sharing proposal work, but satellite operators say that it is costly and in many cases impractical. Some suggestions are to locate antennas for WiMAX and satellite dishes on buildings or structures several kilometres apart, installing filters and using different antenna angles.
“Moving fixed satellite service C-band users to other satellite frequencies is costly and not viable in high rainfall areas” says David Hartshorn, secretary general of the Global VSAT Forum. “The protection of satellite services in the C-band by defining exclusion zones around existing C-band stations is difficult given the number of satellite stations already deployed, many of which are receive-only type stations which are not registered.
Given these constraints, the only responsible alternative would appear to be to find other spectrum in which the terrestrial mobile services can operate”, he said.Globally there are 160 geostationary satellites operating in C-band and nearly two out of every three commercial satellites under construction will use the current satellite frequency allocations in C-band. C-band issues are on the agenda of the ITU World Radio Conference (WRC07) to be held later this year.
At the Conference Preparatory Meeting held during February this agenda item was hotly debated and is considered by many to be the most important issue on the WRC07 agenda, The Global VSAT Forum has urged all operators to influence their national regulators that deployment of mobile broadband services in C-band is not an option and that the current status on C-band be maintained.
In the next few months we will clearly see the battle for spectrum increasing. WiMAX is enjoying a major thrust and according to the industry, C-band is the spectrum to deliver broadband for both fixed and mobile services.
Where does that leave the cellular and banking industries?
They rely on VSAT services for backhaul and connecting ATMs. Is it a question of closer co-operation or technical innovation? I guess time will tell.
Originally published in EngineerIT
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