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 […]

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.

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  1. Satellite Guys To WiMAX: Why You Hate Us! | Om Malik | Voices | AllThingsD Monday, March 17, 2008

    [...] Read the rest of this post Print all_things_di220:http://voices.allthingsd.com/20080316/satellite-guys-to-wimax-why-you-hate-us/ Sphere Comment Tagged: GigaOm, WiMAX, Om Malik, Voices, satellite, wireless | permalink [...]

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. tech news blog » Satellite group calls out WiMax over interference Monday, March 17, 2008

    [...] Om Malik points out, the industry group “has conflicts out the wazoo”, so consider the study’s [...]

  7. Where we tonight shall camp?….The top blogs of the day. the newest report , see and reply me some comments. Thanks.

  8. Dilema wimax si inovatiile intel Wednesday, March 19, 2008

    [...] WiMax interfereaza cu undele de transmisii ale satelitilor si se cam bat cap in cap. Nasoala stire, mai ales ca au descoperit acest inconvenient tocmai acum cand se vorbea de adoptarea wimax pe [...]

  9. Top 3 saptamana 10 (17-21 mar ‘08) | Vlad Stan Sunday, March 23, 2008

    [...] Wimax interfereaza cu semnalele digitalte Satelit. via CTI97 [...]

  10. 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.

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