Satellite Guys To WiMAX: Why You Hate Us!

17 Comments

When it comes to wireless broadband, WiMAX is one technology that has some bad juju. You have two of its premier proponents in the U.S., Clearwire and Sprint, riding leaky boats in rocky financial seas. You have LTE as a potential competitor, thanks to backing from AT&T and Verizon. And now there is a new report out that says WiMAX causes interference with satellite communications transmitted in the C band frequency.

Of course one has to take the report with a pinch of salt since it has been released by Florida-based Satellite Users Interference Reduction Group (SUIRG), which has conflicts up the wazoo. They conducted tests to “measure interference levels generated by fixed WiMAX transmissions into an FSS satellite receiving station.” The tests found that the “WiMAX transmit signal could cause significant problems to a satellite digital signal well in excess of 12 km distance.”

A sharp reader points out that this is a problem with 3.5 Ghz fixed wireless/WiMAX solutions, which is different from the spectrum Sprint & Clearwire are using/planning to use. 3.5 Ghz is very popular for WiMAX in overseas markets.

Any readers who are experts in satellite communications, and want to read the report, we would love to hear from you as to what you make of this whole issue.

17 Comments

Jean Francois Permal

Hi,
I live in a small Island in the Indian Ocean, namely Mauritius. I was able to watch Tv channels by approximately seventeen satellites on C Band very good, but now there are many interferences and sometimes no signals at all. I think it’s a problem of Wi-Fi or WiMax. Please help me to have a solution.Is there a filter or any solution for that. please help me?
Kind Regards

Jean Francois.

dunhate

I’m in Burma. We used a C band satellite dish like most in Asia. I’m not sure if my LNB is extended C band or just regular. Will need to check again. Anyways, my neighbor put up a Redline Wimax antenna aimed at another antenna across the street. It’s not directly aimed at our dish, but their beam is probably like 2 feet away from the edge of the dish and at same height too. I’m guessing it’a 3.5 GHz Wimax which is more popular in Asia than the 5.4Ghz.
So now my satellite TV keeps getting those pixels blocks like a scratched CD. Even those most channels are around 3.7Ghz, the Wimax antenna is screwing it up =(

Tom Wright

The real problem with Satellite is the economical feasibility..and the avail..If you are targeting the developed countries that have no infrustructure, typically the GDP, of the masses, can’t justify for investment, you are left with countries that have either oil, war, large mining, hotels, and others..But is a difficult, and dicy, from an investment point of you…I have created / founded several 2 Way Satellite companies, one of them being http://WWW.MENATELECOM.COM…and now I am the VP for Newsat…There is reward in Satellite, but it requires, amble work, from Marketing Analysis, competitve, suppy, GDP, and oh yes the Engineering side..

I think, though, if you use simple satellite access technology, such as SCPC, and use WIMAX as the last mile, my thoughts, are this will replace the InternetCafe providing there is a cost affective CPE…

Anyway, see you all later…!

Ken

I think the report covers more than just problems in North America.
This is a global issue. Large parts of the world specifically the equatorial areas are sincerely affected by rain fade and there for the KU band is not a feasible option.

To add to this Satelite backhaul is still very popular in underdeveloped parts of the world. Only 24 countries in Africa have the privilege of an international fiber optic link and therefore the teleports in Europe and America are very important to them.

Having said that, the main problem with Wimax and BWA is actually on satellites operating on the extended C-Band 3.5 – 3.4 Ghz. The main C-Band does suffer from LNB saturation, but band-pass filters solve this quite effectively.

Overall though, the rf noise levels caused by all this wimax should be a concern not only to those suffering from interference but to all of us who care for the environment. We are now exposed to -20dBm of RF emission in every major city in the world, what this means for the future, we are yet to really find out.

Ken,
Nairobi Kenya.

eduardo garza

Sorry ,,,,,,,Correction…..

I’m no expert but in my experience in Monterrey, Mexico the WIMAX has seriously affected some areas who have DSS Directv (ka & Ku band )where the local telephone carrier (axtel) is starting to use motorolas Wimax solution. Since they changed and started operating the WIMAX solution . The interference has become a mayor disruption in the reception . The interference is so strong thats makes you unable to see almost any channel/transponder. Lately I been went around asking the neighbors in the area about there DSS reception and the majority comment that they have problems lately in there reception . The majority comment that they can’t watch almost any channel.

Again I no expert on this area hope this may help in any way.

eduardo garza

I’m no expert but in my experience in Monterrey, Mexico the WIMAX has seriously affected some areas who have DSS Directv where the local telephone carrier (axtel) is starting to use motorolas Wimax solution.Since they changed and started operating the WIMAX solution .The interference has become a mayor disruption in the reception . The interference is so strong thats makes unable to almost any transponder.Lately I been asking questions of there DSS reception and the majority comment that they have problems lately in there reception around in the area. The majority comment that they can watch almost any channel.

Again I no expert on this area hope this may help in any way.

luisgj

I disagree that rural private users will be the most affected by WiMax interference to satellite C-Band. I also disagree that most C-Band television providers have moved to Ku-Band. Tell that to HBO, ESPN, Discovery, etc, etc, etc.. There are gigahertz of C-Band transmissions into cable head-ends, network stations, you name it. And not just TV, but private networks, G0v networks, etc. And where you might be confortable with moderate interference, you can’t expect businesses with millions and millions of dollars riding on their transmissions to sit idle.

Mike Puchol

Matt: these exclusion zones will apply to registered FSS sites, not to normal sat TV subscribers I assume. These private users are the ones most at risk from interference.

Matt Liotta

To add to what Kevin said, there is no 3.5Ghz WiMAX in the US. However, there is 3.65Ghz WiMAX in the US, but the FCC has created 150km exclusion zones around the FSS locations. Any operator wishing to use 3.65Ghz within the 150km exclusion zone needs written permission from the FSS owner.

Kevin

Om,

If you read the SUIRG test procedure you see that the WIMAX base station and devices that they are testing is in the 3.5 Ghz band. While this may be important to SUIRG and licensees in that band, it is not the band that Sprint and Clearwire are using. Sprint and Clearwire are licensees in the 2.5Ghz band.

Mike Puchol

I agree with most of what the report says, but I think there are also some problems with it. While it is true that there are still C-Band television providers (which is the main activity that takes place in this band), most of them have moved up to Ku-Band, and modern receivers and low-noise LNBs can work through all but the harshest weather conditions.

The usefulness of C-Band for disaster recovery, mentioned in the report, is not really that great, as the antennas needed to operate are much larger by definition, and not particularly easy to deploy in disaster scenarios. In disaster recovery, traditional HF and VHF are much more useful than any satellite based system, as radios can even be built with cheap COTS parts, and you don’t need a service account with anyone to operate them.

What is certainly true is that the effective power received by a FSS from a WiMax station will be much higher than that from a satellite, and the LNB is going to be affected by the radiation entering from the sides, causing a very poor SNR.

While there is genuine concern for interference to FSS stations by WiMax, the C-Band is large enough to accommodate both services with moderate interference between them, and most importantly, RF spectrum is scarce enough today to warrant imposing work on one party to adapt its space to a second user.

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