- This topic has 65 replies, 1 voice, and was last updated 2 months, 1 week ago by Mohamed.
2nd March 2007 at 19:38 #46519PixGuest
sorry… i’m more interested in helping on practical issues than explaining the definitions of some parameters… i’m just too lazy. furthermore, it is my work, so i should get paid for doing so 😉
thanks for understanding,
pix13th March 2007 at 05:08 #46520PromodGuest
Is it necessary NECI value is enabled dual-rate in network to support all class mobile? Pls suggest me..
Promod20th March 2007 at 12:15 #46521PROMODGuest
I HAVE LOW TCH AVAILABITY IN SOME OF THE CELLS AND IN THAT SOME CELLS ARE HAVING DCR IS VERY GOOD AND SOME CELLS ARE HAVING WORST DCR. IS THAT TCH AVAILABILITY IS GOING TO AFFECT THE DCR AND HSR IN THE NETWORK?
EX:TCH AVAILABITY IS 27%
CASE1:DCR IS 1.3 AND HSR IS 98.23
CASE2:DCR IS 7.8 AND HSR IS 70.45
PLS SUGEEST ME21st March 2007 at 07:24 #46522PixGuest
i don’t know what is NECI…
regarding the tch availability, i answered in another of your thread.21st March 2007 at 12:55 #46523PROMODGuest
1.can i know the reason why it is getting reduced? Is it due to hardware issue or due to some other reason?
2.Why it will affect the HSR due to low TCH availability even though there is no congestion and no hardware alarm?21st March 2007 at 14:34 #46524PixGuest
1. usually, the availability is only related to the physical availability of the hardware. If a TRX is down or locked, then it is unavailable.
2. if low tch availability leads to tch congestion, then you will measure a low HSR
if low availability doesnt lead to tch congestion, then you have no problem 😉23rd March 2007 at 05:31 #46525PROMODGuest
Can u tell me how we will calculate the TCH assignment depending on the TCH availability and TRAFFIC?23rd March 2007 at 09:12 #46526PixGuest
you can’t calculate the number of TCH assignments according to the traffic(erlang) and the TCH availability only…
You also need to know the call mean duration… and you can’t take into account the TCH availability, it doesn’t enter in the formula 🙂
tch assignments = TCH traffic(erlang) / call duration.24th March 2007 at 05:43 #46527PROMODGuest
If i use the adjcent freq in the different site which are looking face to face cell with different BSIC what will be the result? As far as i observed HANDOVER is becoming delay due to Adjcent freq? but it won’t make handover failure because in GSM we should maintain 200kz difference in each freq.Am i correct Pix. and it also apply in the with the same BCCH and different BSIC.
Pix can u tell ur comments on this issue.24th March 2007 at 07:08 #46528pixGuest
1. adjacent channels neighbours : it will cause a voice degradation during HO, and if it happens that the
neighbour cell > (serving cell + 9dB)
then you will face voice quality issues during the talking as well, not only the HO.
C/Iadj > -6dB (3GPP recommendations) (or is it -9dB ?)
Same frequency :
C/I > 12dB
So you need to have the serving cell with a signal higher by 12 dB than the neighbor cell using the same frequency. That can be difficult to obtain !!
And it is not possible to declare an adjacency between cells using same BCCH frequency (even if different BSIC). It is forbidden.29th March 2007 at 05:39 #46529promodGuest
Can u tell me how GHOST RACH will affect the SDCCH? can you explain it.29th March 2007 at 09:25 #46530pixGuest
To be simple, you can consider ghost rach as “useless” signals which are decoded by the BTS as “useful” signals.
So when receiving those “dummy” signals, the BTS will consider it is a “RACH” access and will start allocating a SDCCH for it.
Step 2: the bts has allocated the SDCCH and sends a response to the MS: “Go to this channel”. But since there are no MS (the original RACH signal was not generated by a MS in the 1st place !), there is no answer in uplink. The SDCCH is anyway “reserved” and will be deallocated after the expiry of a certain timer.
So the ghost rach can lead to sdcch congestion, if it is in very large amount.30th March 2007 at 21:00 #46531EmmanuelGuest
we are experiencing very low handover success rate 7.8% or 5% within a site for a whole 24 hr period.
the site is a stand alone, therefore no other neighbors are defined except its cells.the BCCH frequencies are has the required 200KHz seperation.
today, we decided to delete and recreate it again, the results shows no improvement.Statistics shows that cell 2 is trying to handover to cell 2 but may be out 0f 29 attempts,only 1 or 2 will be successful.
the site configuration is 2+2+2, and we are using synthesizer FH.
can some one help me resolve this issue please??31st March 2007 at 08:04 #46532PixGuest
what do you mean “cell 2 is trying to handover to cell 2” ? i think you made a typo error ?
could you please write down the HO requests, the HO attempts and the HO success for each couple of cells ?
Now, at a first glance:
– BCCH separation : 200 kHz between 2 neighbors is too small. You need at least 2 channels separation (= 400 kHz) for instance : bcch(1) = 12 and bcch(n) = 14.
– 29 requests.. it is very small. This value is too low to make correct statistics. It can be due to just one or two mobiles trying to perform “emergency ho” in very bad conditions…
hope it helps..
pix31st March 2007 at 18:20 #46533TufailGuest
I wanna know y Rach sucess decreases if the RxLevMin is increased above -100(i.e -98,-96 in nineties etc)
Thanks in advance