WiMax in Portland OR – High Speed but at what Cost?

WiMAX has arrived in Portland, Oregon via the Sprint/Clearwire  service named “Clear” so I thought I would share some interesting highlights of the WiMAX roll-out thus far. 

WiMAX  from Sprint is proving to provide amazing download speeds as shown in this video report from New York City

However, there are concerns especially in those areas where the 3.5 GHz band is being utilized. One example is the CBS-owned broadcaster KYW in Philadelphia. Something was interfering so badly with the network feed coming off its C-band satellite downlink that the picture and sound were freezing up several times a minute — not a good thing in primetime. It turns out it was the interference emanated from a WiMax service provider testing equipment in the 3650-3700 MHz band that the FCC authorized for WiMax and other wireless broadcast access services just last year.

The problem for broadcasters using the C band to import programming (which is basically every one of them in the United States) is that the upper end of the 50 MHz band abuts the lower end of the satellite C-band downlink frequencies, which run from 3700 MHz to 4200 MHz.

While Sprint is using the 2.5GHz band far away from the C band broadcast frequencies,  both Verizon and AT&T  have won an FCC-auctioned licence to use the 3.5 GHz band. 

Of course the 2.5 GHz band is not entirely in the ‘clear’; some Portlanders are wondering if it is to blame for the recent rash of XM radio outages. XM radio operates two satellites, cleverly nicknamed “Rock” and “Roll” which operate between 2333 and 2344 MHz; when you factor in intermodulation distortion, this could indeed be a factor. The other problem could be that XM finally reduced the power output of their terrestrial repeaters which have been frequently cited by the FCC as broadcasting above authorized power levels. WiMAX vendors have been howling for this to happen for some time and, if it now has, XM could be finding themselves unable to provide the same level of coverage. 

What are your thoughts on WiMAX and on the RF spectrum congestion in general? 

In future posts I had thought to touch on some things that came up in my research such as “4G – WiMAX vs. LTE”, “Is RADAR interference really an issue?” and “How smart radios (i.e. Cognitive/Software Defined Radios) deal with RF spectrum congestion”. Of course, I am always open to suggestions!

-Louis

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