- This topic has 68 replies, 1 voice, and was last updated 8 years, 4 months ago by Rakesh solanki.
18th August 2009 at 09:14 #54408VanderleyGuest
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 subscribers 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)17th November 2009 at 21:25 #54409suhaibiGuest
which could be the causes of the expiry of T200?18th November 2009 at 04:58 #54410BijoyGuest
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
Bijoy18th November 2009 at 06:48 #54411BinitGuest
Idle SDCCH Threshold N1=2
TCH Minimum Recovery Time(s)=60 sec is the current status of one site and there is sdcch blocking and tch blocking .what value of these two parameter will solve my both problem.18th November 2009 at 07:32 #54412BijoyGuest
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
Bijoy3rd May 2010 at 14:33 #54413davidGuest
anyone knows suggested values for T200 timers for GSM over satellite?5th May 2010 at 18:15 #54414danekabaGuest
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.
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plz i need your suggestion.7th May 2010 at 06:07 #54415BijoyGuest
Keep T200 as 1400 ms with SIGDEL=LONG for Abis over satellite.
Bijoy9th July 2010 at 05:10 #54416praveshGuest
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.9th July 2010 at 05:21 #54417BijoyGuest
MAXRET can be set to 4 in case of Abis over satellite.Also,set TTALONG to 15 desisecs.
Bijoy12th July 2010 at 11:49 #54418HARSGuest
Radio link time out value ?12th July 2010 at 12:55 #54419BijoyGuest
RLT can be kept the same as when normal.
Bijoy27th July 2010 at 12:28 #54420PraveshGuest
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 coorelated29th July 2010 at 09:12 #54421BijoyGuest
TTALONG in the BSC controls the value of the time-alignment timer.Time Alignment is a mechanism used between the BTSs and the transcoders to minimize the time speech and data frames are stored in the BTS before being sent out on the radio interface.The time-alignment timer TTA is located in the BTS and it starts when the BTS sends time-alignment change information to the transcoder and it stops after receiving a response from the transcoder.
TTALONG will be used for TGs where SIGDEL is set to LONG.SIGDEL is set to LONG for Satellite A-bis.There are Ericsson specific parameters.
Bijoy3rd September 2010 at 01:17 #54422MakarandGuest
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.
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