What is the TRB and SRB Reset in WCDMA?TRB- Traffic Radio
BearerSRB-Signalling Radio BearerBoth uplink and downlink
interference causes call drop.In downlink, when the active set
CPICH RSCP is greater than 85 dBm and the active setEc/Io is
smaller than 13dB, the call drop is probably due to downlink
interference (when the handover is delayed, the RSCP might be good
and Ec/Io might be weak, but the RSCP of Ec/Ioof cells in monitor
set are good). If the downlink RTWP is 10 dB greater than the
normal value (107 to 105 dB) and the interference lasts for 2s3s,
call drop mightccur.You must pay attention to this.Downlink
interference usually refers to pilot pollution. When over three
cells meets the handover requirements in the coverage area, the
active set replaces the best cell or the best cell changes due to
fluctuation of signals. When the comprehensive quality of active
set is bad (CPICH Ec/Io changes around 10 dB), handover failure
usually causes SRBreset or TRB reset.Uplink interference increases
the UE downlink transmit power in connection mode, so the over high
BLER causes SRB reset, TRB reset, or call drop due to a
synchronization. Uplink interference might be internal or external.
Most of scenario uplink interference is external.Without
interference, the uplink and downlinkare balanced. Namely, the
uplink and downlink transmit power before call drop will approach
the maximum. When downlink interference exists, the uplink
transmitpower is low or BLER is convergent. When the downlink
transmit power reaches themaximum, the downlink BLER is not
convergent. It is the same with uplink interference. You can use
this method to distinguish themVery good idea to do classification
based on EcNo or RSCP for IRAT HO causes. You can do it easily in
Ericsson network based on GPEH data, where entire IRAT HO process
fully presented with all RF information correlated.As for s52d
statement on limited KPIs number and SON, I would like to say that
as for number of KPIs you are 100% correct that it should a limited
number of Key PI for level one performance monitoring, but for
solving issues like IRAT....KPIs is not sufficient and you need
more info about RF environment and causes. IRAT HO problem is
pretty serious you can split at least for two parts:1. Dedicated
mode IRAT HOs that may significantly affect overall network Drop
Rate especially for CS connections, since it is a HHO with RAT
change.2. Idle mode 3G coverage lost and ping-pong 3G
selection/reselection where excessive signalling for LU exists in
UTRAN and GSM networks, this may cause serious problem of lost
incoming calls in case where LACs between GSM and UTMS are not
synchronized (i.e. not the same). During RAT selection and LU your
mobile is not available for incoming calls for 3-5 seconds. Once
RAT Reselection occurs too often, then probability to get Mobile Is
Off (MIO) too high.As for SON....to make dynamic changes for IRAT
HO parameters per cell basis....I think this is not efficient at
all. The real SON taking care for most significant issues that may
affect the root cause for unnecessary IRAT HO....bad RSCP and bad
EcNo....this is can be treated efficiently in SON via antenna etilt
optimization...such SON already exists and performing.....if you
would like to know more on this issue I can share some info with
you. Very good idea to do classification based on EcNo or RSCP for
IRAT HO causes. You can do it easily in Ericsson network based on
GPEH data, where entire IRAT HO process fully presented with all RF
information correlated.As for s52d statement on limited KPIs number
and SON, I would like to say that as for number of KPIs you are
100% correct that it should a limited number of Key PI for level
one performance monitoring, but for solving issues like
IRAT....KPIs is not sufficient and you need more info about RF
environment and causes. IRAT HO problem is pretty serious you can
split at least for two parts:1. Dedicated mode IRAT HOs that may
significantly affect overall network Drop Rate especially for CS
connections, since it is a HHO with RAT change.2. Idle mode 3G
coverage lost and ping-pong 3G selection/reselection where
excessive signalling for LU exists in UTRAN and GSM networks, this
may cause serious problem of lost incoming calls in case where LACs
between GSM and UTMS are not synchronized (i.e. not the same).
During RAT selection and LU your mobile is not available for
incoming calls for 3-5 seconds. Once RAT Reselection occurs too
often, then probability to get Mobile Is Off (MIO) too high.What is
the TRB and SRB Reset in WCDMA?TRB- Traffic Radio
BearerSRB-Signalling Radio BearerBoth uplink and downlink
interference causes call drop.In downlink, when the active set
CPICH RSCP is greater than 85 dBm and the active setEc/Io is
smaller than 13dB, the call drop is probably due to downlink
interference (when the handover is delayed, the RSCP might be good
and Ec/Io might be weak, but the RSCP of Ec/Ioof cells in monitor
set are good). If the downlink RTWP is 10 dB greater than the
normal value (107 to 105 dB) and the interference lasts for 2s3s,
call drop mightccur.You must pay attention to this.Downlink
interference usually refers to pilot pollution. When over three
cells meets the handover requirements in the coverage area, the
active set replaces the best cell or the best cell changes due to
fluctuation of signals. When the comprehensive quality of active
set is bad (CPICH Ec/Io changes around 10 dB), handover failure
usually causes SRBreset or TRB reset.Uplink interference increases
the UE downlink transmit power in connection mode, so the over high
BLER causes SRB reset, TRB reset, or call drop due to a
synchronization. Uplink interference might be internal or external.
Most of scenario uplink interference is external.Without
interference, the uplink and downlinkare balanced. Namely, the
uplink and downlink transmit power before call drop will approach
the maximum. When downlink interference exists, the uplink
transmitpower is low or BLER is convergent. When the downlink
transmit power reaches themaximum, the downlink BLER is not
convergent. It is the same with uplink interference. You can use
this method to distinguish them
