Harm claim thresholds for satellite earth stations

I'm reasonably confident at this point about deriving harm claim thresholds for cellular neighbors and TV receivers (see e.g. the TPRC 2012 paper http://ssrn.com/abstract=2018080). Here's a first cut (a few months old, but I'm behind on blogging...) at thresholds for satellite earth stations.

TV/cellular guard bands - second thoughts

In a recent post ("The FCC's TV/cellular guard bands don't compute") I wondered whether the guard bands between TV and cellular service that the FCC proposed in its Incentive Auction NPRM (pdf) had been designed to make room for more unlicensed in the TV bands. Having spoken to some experts, I’ve concluded that I was probably wrong about that: my new best guess is that they’re a benefit for the cellular industry.

The FCC's TV/cellular guard bands don't compute

The FCC incentive auction NPRM [1] proposes 6 MHz guard bands between cellular and TV services (actually 6-11 MHz, depending on how the auction works out). The number is arbitrary, and could well have been chosen on political grounds to make room for more unlicensed in the TV bands.

The impact on interference from cellular systems into TV receivers is much the same whether the guard band is 1 or 20 MHz: most receivers will be unaffected, and for the small but significant number that suffer harm (0.5-5%?), only receiver filters will really help. The real question is: who's responsible for buying and installing those filters - the consumer or the cellular companies?

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.

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.