The potted version of what the EU will spend lots of money to find out ...
This whole issue has been kicked off by the government in Germany (particularly) wanting to help a few people in rural areas get access to the internet - you know, the ones who don't have DSL or cable. They thought that the spectrum freed up by the changeover to digital TV could be used for better purposes than more mindless TV programs (e.g. access to internet porn), so they suggested that people could use defunct TV spectrum for fixed wireless radio using 4G technologies.
But the broadcast/cable media companies know that any internet access is likely to affect their ability to squeeze money out of punters, so the battle started. Step up AGNA, the German Cable association with a test to prove how dangerous the wibbly-wobbly waves of LTE were. They fired a full power basestation signal into a 'house' with a cable settop box **from 80m away** and noted that it caused some distortion on the analogue telly picture (DVB-C signals could use error correction and there was no visible effect). Not many people actually live within 80m of a basestation, especially one operating near the GSM band. Anyone care to work out what percentage of a rural GSM cell lies within 80m of the basestation?
When they tried it with a pseudo LTE terminal next to the cable box with a 5dBi antenna pointing straight at it, there was a clear effect on both analogue and digital TV signals on the same frequency. The effects could be seen even through a couple of 'typical apartment walls' in the worst case.
Oh, I forgot to mention that they fixed it so the cable signal so that it was on the same frequency as the LTE signal. Analogue cable TV signals (in Germany) use lower frequencies, below 650 MHz IIRC, so the chances of LTE and analogue cable being on the same frequency are pretty much zero.
In reality there is only a four DVB channel overlap between Euro cable (112 - 858 MHz) and LTE in the digital dividend band uplink (832 - 862 MHz), and four on the downlink (791 - 821 MHz). And let's forget that no-one in Germany actually uses those top channels, and they happen to be the worst channels for cable (higher frequency = higher loss in the cable). And the problem all starts because the cable receiver box has as much shielding as a piece of cotton, so is susceptible to any nearby signal on the same frequency (in the band 112 - 858 MHz).
So in the end, the EU will say
- cable settop boxes are crap and should be designed to withstand higher levels of interference
- only four (unused channels) are at serious risk from LTE in the same building as the settop box
- four more channels are also at risk if you live closer than 120m to the LTE basestation (less than 1% probability by area in a rural environment, even less by population)
- cable operators have more than 85 other channels available and each of these can carry a 8-10 TV programs plus a large number of radio stations, so the loss of a few channels at the top of the band should have almost no effect on cable TV capacity, especially when more analogue cable channels are switched to digital.
If anyone knows if the technical aspects of cable broadband (channels, bands etc) would make a difference, I'd be happy to modify my views.
But in the end, if you use LTE to give broadband to people who don't have access to the internet, they're not going to have cable TV either.
Biting the hand that feeds IT
