call drop due to expiry of T200 timer

Guys,
correct me if I am wrong but after expiry of T200 the only thing that happens is sending again the message (for example ASS CMD on SDCCH). The channel is released with the error indication after N200+1 repetitions.
So yes the chance for SD blocking is higher if you increase the T200, because you keep the channel busy (for total of (N200+1)xT200…and there is no MS to respond.
Here is the Siemens opinion:
To achieve an optimum
radio interface performance (from the subscriber’s point of view), the
timer values for T200 should be set in such a way that
– a Um layer 2 frame retransmission should take place at the earliest
after a time period the MS needs for the transmission of an
acknowledgement of a received layer 2 frame
– a Um layer 2 frame retransmission should take place as early as
possible when the aforementioned time period has passed and no
acknowledgement was received from the MS
– unnecessary retransmissions are avoided.

so they recommend 145ms T200, and default is 220ms (N200 is 23 for SD)

Hi Krish/Pan/Pix
If you increase the T200 timer for SDCCH.it will improve the SDCCH Drop at the cost of SDCCH Blocking,that’s it.But only upto a certain extent.

Certain Vendors like,Nokia,Ericsson,Huawei has actually got some new features like repeated SACCH & FACCH to improve the Signalling Drops & HOSR

Br\\
Bijoy

Binit
These are recommended values in Huawei.Have you defined adequate SDCCH/TCH checking the SDCCH/TCH Traffic?
If dimensioning is OK,& you want immediate improvement in SDCCH/TCH Blocking enable “Immediate Assignment on TCH” to reduce SDCCH Blocking.For TCH Blocking,lower the triggering threshold for HR,i.e,use more HR’s

Br\\
Bijoy

in ERICSSON switch . we have one subscriber which can not make call in roaming but he can receive: i have checked all subcription status: HGDSP:msisdn=…, all; there is not trouble just this parameter i dont understand it.

SERVICES RESTRICTED IN VLR
RSP
7
plz i need your suggestion.

Hello Bijoy i am trying to run Abis over satellite and tried T200 from 1.5 to 3 seconds.

Can you please let me know how much is the optimum retry we should set.

Radio link time out value ?

Thanx!! Bijoy can you please specify what is this parameter TTALONG i hope it is vendor specific and how i should map it with my system.I also see in one of the message you are mentioneing SIGDEL=LONG is it coorelated

Hi bijoy,
exactly when t200 starts?
Is ho failure is one of the cause for data link failure?
In ho failure which data link gets broken ,i think it must be at source side , then how it gets restored as its nt necessary that call may drop after data link failure.