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Bug #3395

closed

Uplink CS/MCS control is broken osmo-pcu is used with osmo-bts-trx/osmo-trx

Added by ipse over 3 years ago. Updated almost 2 years ago.

Status:
Resolved
Priority:
High
Assignee:
Target version:
-
Start date:
07/14/2018
Due date:
% Done:

100%

Spec Reference:
TS 05.05

Description

Not sure which project to assign this to.

GprsMs::update_cs_ul() function (osmo-pcu/src/gprs_ms.cpp) is used to control the UL CS/MCS mode and in its current implementation is relies on the Quality "Q" value reported by L1. Osmo-trx does not really calculate the SNR of the link and thus osmo-bts-trx always report Q as 0. This misleads the current algorithm which always drops the CS/MCS to the lowest possible mode (CS-1/MCS-1).

Possible solutions I see:
1) Use another metric, like BER which are reported by osmo-bts-trx. A similar method is already used by the DL CS/MCS control.
2) Implement SNR calculation in osmo-trx. A better way, but much more involved.


Files

compute_edge_ci.diff compute_edge_ci.diff 3.36 KB fixeria, 10/04/2019 08:33 PM

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Related to OsmoPCU - Bug #3834: MS set_mode()/set_current_cs_*() inconsistent resultsResolved03/12/2019

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Related to OsmoPCU - Bug #1833: UPLINK MCS gets reduced from MCS9->MCS6 when good radio condition existsFeedbackarvind.sirsikar10/25/2016

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Related to OsmoTRX - Bug #4373: OsmoTRX calculates relatively lower C/I values for EDGE/8-PSK bursts (compared to GMSK)Resolvedfixeria01/22/2020

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