Tuesday, October 30, 2012

TV whitespace vs. cellular power limit anomalies

In the previous post, I considered interference between cellular base stations and TV receivers. What about interference between cellular handsets and TV? Considering this case highlights striking contradictions between the low power allowed for TV whitespace devices and the high power the FCC proposes for cellular operation: 20 dBm for whitespace personal devices but 37 dBm for cellphones, in both cases with a 6MHz guard band.

Monday, October 29, 2012

Post-auction cellular interference into TVs?

How many TV receivers will be affected by interference from cellular services as a result of the FCC’s "incentive auction" plan?  The FCC’s proposal doesn’t venture an answer; I don't think it even asks the question. Ofcom’s technical analysis in the UK’s rearrangement of the TV bands to accommodate more cellular service suggests that the number will be small, but not negligible. Ofcom therefore decided to require cellular operators to install filters on TV sets where there is a problem; the FCC has not raised this possibility.

In summary, the UK modeling suggests that TV reception will be affected in about 5% of  homes if there's a 11 MHz guard band between TV and cellular channels; the FCC's proposed guard band will be 6 - 11 MHz, depending on auction outcomes. By far the most effective way to mitigate this interference is by installing a TV receiver filter in affected homes.

Thursday, October 25, 2012

Receiver regulation: Why no progress?

(Written with Madelaine Maior, Silicon Flatirons research fellow)

There’s an emerging consensus that the role receivers play in interference should be recognized in wireless regulation. But why has it taken so long to come to a conclusion about the performance of receivers?

Saturday, October 20, 2012

Spectrum sharing is not a partisan issue – NOT

After his keynote at Dyspan yesterday, PCAST member Mark Gorenberg and his podium guests (and spectrum report co-authors) Dennis Roberson and Michael Calabrese were asked about the political prospects for the PCAST spectrum sharing recommendations (pdf). I can’t remember exactly who said what, but the message was that spectrum sharing wasn’t a partisan issue. Not so.

Thursday, October 04, 2012

Three meanings of "spectrum efficiency"

“Efficiency” is a word of power, chanted when someone wants to bewitch an audience with the potency of economics. It’s often used in wireless policy, and I’ve realized that even when “spectrum efficiency” isn’t purely a fetish and is used to refer a ratio of input divided by output, the amounts compared depend on whether the speaker is an engineer or economist.