[osmocom-event-orga] 850 mhz, 2600 mhz, no 1800

[Harald Welte]

On Tue, Dec 10, 2019 at 08:51:53PM +0100, Alexander 'lynxis' Couzens wrote:

> BNetzA will license us 850 band (5mhz).
> Telefonica will license use 2600 band (10 mhz, 100mw).

Sad (no 1800).  I guess that's final?  Or are you pursuing alternatives with other operators?

> I would like to have a LTE setup.

The eNB from camp can be used again.  At least all but one which seemed
broken, but meanwhile I think I obtained 1-2 more.  So I guess you could
operate 6-7 of them.  It will by far be insufficient to cover the fair grounds.

Make sure you place them physically at very elevated locations to have line-of-sight
to most subscribers.  I think one of the problems at the camp was that they were at
less than 2m height, which means every human being in between the user and the eNB
is a large attenuator.

> How should we use the 850 band?
> Should we use it for GSM? UMTS? Or both? Like GSM in the edges, UMTS in
> the middle?

I think due to the very different spectrum usage of narrow-band TDMA GSM
and wideband CDMA in UMTS  you will very likely get significant interference
in the GSM -> UMTS direction.  Particularly on uplink, where it's actually
more difficult to manage as the phone might just be ad the edge of a GSM cell
(downlink very weak, no interference) but then the phone sends at maximum power
 - in all directions, not just in the direction of your GSM BTS.

So from a RF / physical point of view, I would argue against operating two
technologies on the very same channel, unless you can more or less prove that
due to physical distance/isolation there won't be any interference.

-- 
- Harald Welte <laforge at osmocom.org>            http://laforge.gnumonks.org/
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