- This topic has 12 replies, 1 voice, and was last updated 10 years, 5 months ago by gaurav kumar.
18th September 2006 at 07:47 #45747sanjayGuest
Which BSC are u using? Its quite possible to iniatite a call in ericsson BSC without SDCCH by using TCH for call set up. Here CHAp value is set at 2.18th September 2006 at 08:04 #45748yogesh Bonsai IndiaGuest
actully this in my opinion called FACCH call setup18th September 2006 at 22:17 #45749PixGuest
hello yogesh and sanjay,
could you please detail the procedure for such a TCH / FACCH call setup ?
thank you19th September 2006 at 06:04 #45750sanjayGuest
In my opinion, here during call set up, when a MS requests for a channel in RACH, instead of asking the MS to tune to SDCCH for further call set up procedures, the MS is directly alloted a TCH which in turn would do the neccessary signalling for call set up.19th September 2006 at 09:55 #45751Iwan SuwandiGuest
Can you help me, how to reducing EXCESSIVE TA. i has checked neighbour relation, ACCMIN and Layer Treshold.19th September 2006 at 23:08 #45752PixGuest
Thanks for the answer. I understood you’re using this on your Ericsson network ? Does it create too much signalling load on the BCCH ? I’d be interested to see the messages/procedures schematics of such a call setup…
Excessive timing advance, and no neighbor ? Your problem shouldn’t be excessive TA, but rather : “Subscribers that are very far away manage to connect to this cell, and they have a very poor call quality. Such a situation degrades the QoS for this cell (high call drop, low cssr…).”
Well, you can simply set a TA threshold. For instance, TA_LIMIT = 20 … Subscribers after 10km ( = 20 TA / 0.55 km) will not see this cell anymore, therefore they can’t make calls on this cell.
BUT keep in mind that if you reduce the TA limit, you’ll reduce the amount of subscribers that can use this site. In other words, you’ll remove network coverage from a certain populated area. This can have a bad influence on your operator’s image.
Another solution : increase the RXLEV_ACCESS_MIN, from -106dBm to -100dBm and observe the impact. This will filter out all the subscribers that don’t have a RX_LEV strong enough. I prefer this solution, because you don’t limit the cell geographically.
Pix20th September 2006 at 12:10 #45753Iwan SuwandiGuest
This site has default parameter:
RXLEV_ACCMIN = -100 dbm ( has been changes from -106 dbm but no improvement)
LAYERTHR = -95 dbm
LHYST = -3 dbm
TALIM = 61
MAXTA = 63
RLINK UP = 52
RLINKT = 36(has been changed from 52 and no improvement)
You have another solution for me except change TALIM,
Thanks Pix,20th September 2006 at 23:00 #45754PixGuest
with rxlev access min = -100dBm, you still have a poor QoS ?
I would check the path balance of this cell, perform drive-tests, check interference, and check the QoS per TRX. Overall : try to be certain that the hardware is good and the frequencies are clear.
If everything is fine, I would check power control parameters, possibly inhibit DL and UL power control for few hours and check the imapact. I would also implement synth. frequency hopping on a TRX, and force traffic to go on this SFH TRX (to benefit from frequency diversity).
Then I would continue reducing the RXlev access min until I see an improvement. Compare those results with your drive-tests. Where is, geographically, the problem ? Can’t you add an aditionnal site to cater for this area ?
For information, what are the values for:
the Call Drop Rate,
the TCH assignment failure rate, the path balance,
the average timing advance,
the average Rx Lev downlink,
and the traffic in erlang ?21st September 2006 at 07:47 #45755sanjayGuest
Why don’t u reduce the values of RLINK UP & RLINKT to 16. At present these values have been set very high, which means the calls are not being disconnected by either BSC or MS even when they are not able to decode SACCH for a fairly a long time, resulting in call drops.
We haven’t implemented the feauture of call set up through TCH, so I don’t have any practical data to share. But the feature exists in Ericsson BSCs. Any way it shouldn’t load the BCCH.20th November 2008 at 06:18 #45756Masud Parv ezGuest
for a long time i am facing from one site BS288 this from SDCCH drop rate is very bad.Thogh i checked all of our BTS & BSC related soft, feeder cable, Power, Antenna,yet i am facing SDCCH drop reate is bed.
WOULD you give me suggestion how can i solved the problem.?20th November 2008 at 13:35 #45757pixGuest
have you checked interference problems ? perhaps your hardware is fine, but there are bad radio conditions (bad quality, poor coverage or high interference)
Also, can you check on which TRX is located your SDCCH timeslot(s) ?
Maybe this TRX does not carry any call (calls are allocated on other TRX), that’s why there is no call drop on this TRX, only SDCCH drops.)31st August 2010 at 07:39 #45758SUMITGuest
hi i m new in NSN optimization
So plz suggest me the ways to improvr KPI’S for NSN system15th September 2010 at 16:57 #45759gaurav kumarGuest
i m new in NSN optimization and please suggest me for intra handover failure and also for TCH drop and handover failure ,poor dlq also???
how can i rectify these problems???