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Bug #1616

osmo-bts-trx / osmo-bts-octphy doesn't provide C/I information to PCU

Added by laforge about 2 years ago. Updated about 2 months ago.

Status:
Stalled
Priority:
Low
Assignee:
-
Category:
osmo-bts-octphy
Target version:
Start date:
02/23/2016
Due date:
% Done:

50%

Spec Reference:

Description

osmo-bts-trx doesn't pass singal quality information to the PCU socket, meaning that link/rate adaption will of course not work as it i supposed to.


Related issues

Related to OsmoPCU - Feature #1543: link/rate adaption as per spec New 02/23/2016
Related to OsmoPCU - Feature #1536: Implement adaptive CS selection New 02/22/2016

History

#2 Updated by laforge almost 2 years ago

  • Assignee set to msuraev

#3 Updated by msuraev almost 2 years ago

How exactly quality information is passed from DSP to L1 in case of osmo-bts-sysmo? I have trouble locating that place in the code - there doesn't seem to be particular function dedicated to that.

#4 Updated by msuraev over 1 year ago

According to void GprsMs::update_cs_ul(const pcu_l1_meas *meas) in src/gprs_ms.cpp the switch to higher/lower CS depends only on link_qual value. Not sure if some spec covers which measurement is supposed to be used for link rate adaptation. Also, it's unclear yet how to convert the values available in particular BTS to be similar to what is reported by sysmobts.

#5 Updated by msuraev over 1 year ago

  • Status changed from New to In Progress

Note: the DL CS is selected separately in update_error_rate()

#6 Updated by laforge over 1 year ago

#7 Updated by laforge over 1 year ago

  • Related to Feature #1536: Implement adaptive CS selection added

#8 Updated by laforge over 1 year ago

TS 45.008 Annex D contains an "Example Selection of Modulation and Coding Schemes" for 8PSK EGPRS (MCS5-MCS9) based on CV_BEP and MEAN_BEP. Those two values should be reported by a BTS model to the PCU.

For classic GPRS or EGPRS with GMSK, I'm still looking to find similar reference values.

Chapter 8.2 of TS 45.008 contains information on how RxQual and CV_BEP / MEAN_BEP values are computed and encoded.

#9 Updated by laforge over 1 year ago

Some papers:

In genreal, it seems there are BLER and CIR (C/I) based schemes, and that C/I is generally perceived to be superior.

I think the parameters RxLev/Rssi, BER, RxQual (averaged BER) should be provided by ever PHY/L1 and thus be a good candidate for reporting measurements to the PCU for GPRS/GMSK. Plus CV_BEP and CV_MEAN for EGPRS/8PSK

#10 Updated by msuraev over 1 year ago

Version for octphy submitted for review in gerrit # 622 - 624.

#12 Updated by msuraev over 1 year ago

  • % Done changed from 0 to 50

Changes for l1sap and bts-pcu protocols have been merged to master. Octphy implemntation have been merged, osmo-trx is partially implemented (C/I estimation is missing, extensive testing required).

#13 Updated by laforge over 1 year ago

  • Target version set to osmo-bts-trx refresh

#14 Updated by laforge over 1 year ago

#15 Updated by msuraev over 1 year ago

  • Status changed from In Progress to Stalled

#16 Updated by laforge 11 months ago

  • Subject changed from osmo-bts-trx / osmo-bts-octphy doesn't provide signal quality information to PCU to osmo-bts-trx / osmo-bts-octphy doesn't provide C/I information to PCU
  • Priority changed from Normal to Low

#17 Updated by laforge about 2 months ago

  • Assignee deleted (msuraev)

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