On 30 Jul 2014, at 02:43, Fredy Kuenzler kuenzler@init7.net wrote:
Is anyone familiar with 3G repeater gear? I'm asking for a neighbor whose family owns a cottage in a Swiss mountain valley with poor 3G reception.
As a licensed amateur radio operator, I know that there is no easy answer.
Things to consider:
"3G" is a term used for the modulation and protocol technology but is not in reflection to the frequency. Traditionally 1900 or 2100Mhz is used but these days you might see 3G on 900Mhz too. If we talk about LTE 4G, we have over 40 official frequency ranges which in theory could be used. And LTE uses technologies such as MIMO with multiple antenna paths to get more throughput. As far as I know in Switzerland 2600MHz and 800MHz are used for LTE besides the traditional GSM frequencies 900,1800,1900,2100. All of these bands have different uplinks and downlink frequencies (FDD).
The chinese repeater products at the end of the day are simply an antenna + amplifier + band splitter. This means they receive the downlink from the outside antenna, amplify it and feed the inside antenna with the signal and on the uplink it does the reverse. The problem arises if the indoor antenna can feed a signal into the outdoor antenna. In this case, the repeater would send a signal to itself and start to oscillate. Secondly, if you look at the frequencies, you would have the need for amplifiers for all the different bands separately and also good band filter. This means the cheap devices simply only operate on one frequency band only. You sometimes see dual band versions but they are already rate.
On terms of the legality I'm not 100% sure as you would start to transmit a frequency which belongs to the operator. Its at least a bit of a grey zone as you don't control the transmission as you only repeat. Maybe with the blessing of the operator this could be ok. I'm sure they do such things for locations such as shopping centers. On the other hand they could as well use microcells in those areas for capacity reasons. Something which is not possible without a wired connection.
The best thing you could do is to put a good outside highly directional antenna and connect it directly to the device. A good antenna is your best amplifier. Also possible is a passive setup with a indoor antenna coupled with an outdoor antenna. This will basically simply change the antenna characteristic of the internal antenna of the device by coupling it with the outdoor antenna. It is never as good as a direct wired connection as you have considerable coupling losses. If this doesn't work, you can still consider adding an active repeater.
Another alternative is to simply put up a microwave point to point link to a location where you have better connectivity and simply relay the connectivity through. But this of course needs another location with power. If i say "microwave", this can be some decent Wifi devices such as a Mikrotik SXT on 5GHz. They cost like 60-110$ a piece.
Any recommendation for gear which is easily installable, more or less plug-n-play, not too expensive (less than CHF 1000) and last but not least legal to operate would be appreciated.
-- Fredy Kuenzler Init7 (Switzerland) Ltd. St.-Georgen-Strasse 70 CH-8400 Winterthur Switzerland
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