Hello All,
Herr Thomas had raised up a discussion about problem with setting of BTS power attribute value. In connection with this question, I recall another problem which has occurred with one of my BTS's. It has a very strange behavior. Its output power is set to 2W. My measure device tells me that receive level at the desired channel is about -24 dBm after station boot-up. This value is very good, no other base station around shows better results.
But right after the very first GSM call the receive level quickly jumps down to -70 or even -80 dBm, this value corresponds to 30mW of output power. BTS station still works and output power is still shown as 2W.
This effect had been discovered with only one of my BTS stations, while other stations work well. Does it mean that it's a hardware problem? Has anyone discovered this problem earlier?
Best Regards, Sergey.
On Thu, Dec 02, 2010 at 09:58:23PM +0300, Sergey V. Efimoff wrote:
But right after the very first GSM call the receive level quickly jumps down to -70 or even -80 dBm, this value corresponds to 30mW of output power. BTS station still works and output power is still shown as 2W.
In case you are running a multi-TRX BTS: is this the received power level on the TCH of the call or on the BCCH ? If downlink power control is active, the BTS will not send more power than needed on a dedicated channel...
This effect had been discovered with only one of my BTS stations, while other stations work well. Does it mean that it's a hardware problem? Has anyone discovered this problem earlier?
Are the other BTS's configured exactly the same way? As explained, the difference single-trx / dual-trx and downlink power control might explain it.
otherwise, if configuration of bs-11, openbsc and the bs11 firmware is identical, it might well be a hardware issue. But I don't get why it would be related to the first call or not...
Regards, Harald
Hello Harald,
On Dec 3, 2010, at 2:22 AM, Harald Welte wrote:
On Thu, Dec 02, 2010 at 09:58:23PM +0300, Sergey V. Efimoff wrote:
But right after the very first GSM call the receive level quickly jumps down to -70 or even -80 dBm, this value corresponds to 30mW of output power. BTS station still works and output power is still shown as 2W.
In case you are running a multi-TRX BTS: is this the received power level on the TCH of the call or on the BCCH ? If downlink power control is active, the BTS will not send more power than needed on a dedicated channel...
The receive level is shown for BCCH.
This effect had been discovered with only one of my BTS stations, while other stations work well. Does it mean that it's a hardware problem? Has anyone discovered this problem earlier?
Are the other BTS's configured exactly the same way? As explained, the difference single-trx / dual-trx and downlink power control might explain it.
Yes, other stations are configured exactly the same way.
otherwise, if configuration of bs-11, openbsc and the bs11 firmware is identical, it might well be a hardware issue. But I don't get why it would be related to the first call or not...
I am confused. I did not observe this effect earlier on this station. And I do not observe it on other stations. I also don't know why this effect appears after the first call. It really seems to be a hardware problem.
Best Regards, Sergey.
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Harald Welte -
Sergey V. Efimoff