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what happen ?If we change parameter max retran from 2to4(7)
Thak you
KBImmediate Assignment success will improve,but take care of high resource holding time,ie resource utilization will increase leading to congestion.Should be increased only for low traffic cells.
hi bijoy,
Here in one cell i had rach success ratio only 40% .in this i changed tx from 10 to 32 and max retrans from 2 to 7 but no improvement.so can u suggest?
And which load will increase if we change max retrans from 2 to 7?
Hi Krish
To improve Rach Success Ratio,please look for Co-BCCH-BSIC cells in its neighbor.
You can also optimize 3 parameters
1.RACH Min.Access Level
2.Random Access Error Threshold
3.Rach busy threshold.SDCCH Holding time will increase if you increase Max. No. of retransmissions.
Also CCCH Load will increase leading to flow control in BSChi bijoy
Thanks for reply.but here i already cheked co bcch bsic but not here and what is rach access min here we have rx access min.is it similar?
And rach busy threshold and rach error threshold.
And bijoy i agree by increasing max retrans ccch load will increase but how sd mean holding time will increase?because sdcch is not part of ccch.
Hi Krish
Each time MS re-transmits the channel request request message,it means that T3101 timer was expired and the SDCCH assigned by immediate assignment was released.So,if you set max no. of re-transmissions to 7,and if the immediate assignment succeeds after 6-7 attempts it means that in that particular cell SDCCH holding time increases by{T3101 X(6 or 7)}=18 to 21ms per channel request which is very high for High traffic cellshi bijoy,
if i have max retrans 5 then in first trial ms sends channel req to bts abd bts will send it to bsc .after that bsc will send imme assign commnad(this time t3101 will startis it ok?) to bts and bts will send it to ms and ms will send est complete command to bts.
so here est command will be send by ms but we have blocking on bts side so can u clear this things?
and can we play with t3101 timer it is bsc level para?
T3101 will not help in SDCCH Blocking.
Please check for Immmediate assignment reject causes.HI,
i am asking that est command is send by finaly from ms side so how blocking is bts side?
and if i have max retrans 3 then after first rach ms will send again req and it will do upto 3 time so every time it will hold the sd and sd holding time will be 3*3ms = 9 ms which is cconggs is it ok?
Yes,This will increase the CCONGS.Also.check what r the reasons for Immediate assignment reject.
HI,
i am asking again if i will increase my rach from 2 to 4 ok
then ms will send 4 times rach request so how sd will come in this picture and sd mean holding time increase? plz explain…
Hi Krish
Why r u so confused.
For each RACH,Immedite assignment command will be given and SDCCH will be reserved for that request till T3101 expiry.After that SDCCH will be released and MS will send a new RACH……till 4 times.Hope u got that
Hi,
u are right but after first rach if there will be no imeediate assignement from bts side it means no sd reserve in that case?
Hi RG
If immediate assignment command doesnt takes place,it means that there is no available or usable SDCCH.hi,
Thanks for reply. U mean if i have high traffic site and i will reduce max rach from 7 to 2 , then there will be chance of reducing sd blocking? Is it?
And abt rach success ratio – if my first rach will be not sucessed and its like upto four rach then in this case no immediate assignment will come in pitcure because form ms side my rach is not complete then what could be reason? Is it uplink interference?
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