- This topic has 36 replies, 1 voice, and was last updated 13 years, 12 months ago by daniel.
12th October 2006 at 22:21 #45542PixGuest
From what you’ve been saying, the G18 and G9 have separate BCCH already. Thus, your solution about changing the cell reselection offset is effective. However I’m afraid that you will reduce the coverage of G9 cells. Imagine an area which is covered only by the fringe of a G9 cells. The C2 criteria might drop below zero and therefore prevent someone to make a call. It might be safer to increase the cell reselection offet on G18 cells rather than decrease it on G9 celsl.
Don’t forget to set your handovers settings accordingly so the calls will stay on G18 cells (HO Margin, Ho thresholds)
You can also force your cell neighboring list to contain at least 2 or 3 G18 cells.
Finally, you can activate (or optimize) the force directed retry / directed retry in such a way that calls will go directly from a G9 SDCCH to a G18 TCH.13th October 2006 at 15:29 #45543AccentGuest
Nice piece of advise. You are right, both bands have seperate BCCH and SD. Need your advise again, if I push the CRO higher for G18 cells, IMO, there might be difficulty in call setup in G18 cells because the CRO doesn’t reflect the actual SS of G18 cell?
2ndly, during HO in dualband cells, the algorithm starts from evaluating the Layer Priority 1st then Layer Threshold right? Correct me if I am wrong. I will try the HO Margin and HO Threshold tomorrow.. Thanks again..13th October 2006 at 19:06 #45544PixGuest
yes, the G18 level might be too low to setup a call in the end.. you’ll have to fine tune this parameter. maybe increase a little on the G18 and reduce a little on G9… it really depends on your G18 cells density.
Depending on priority, the HO can push/keep a call within the G18 layer. But it also depends on various parameters (which types of HO are activated, the preferred band, …). It looks like you know a good deal about dualband networks, so I believe you set up your network correctly. Next week, I’ll try to have a look through some documents and check whether there is anything else we could use.
Are you having RACH or SDCCH congestion ? Or a critical KPI ? Maybe, if everything is good, you just have to fine tune your parameters. An interesting indicator is the amount of traffic (erlang) carried by G18 cells and G9 cells, and the traffic load. If it is balanced, then I think it is as good as it can get.14th October 2006 at 07:54 #45545AccentGuest
Yes, I am also thinking the same way to adjust CRO of both bands so that it won’t compromise too much on both cells performances. Thanks for the tips. RACH and SDCCH seems to be ok after I had done the CRO setting (manage to offload some of the SD traffic to G18). I think this is the maximum setting that I can achieve. Setting the offset too aggresively will only improving one cell but the other one will just getting worse. Long term solution will be adding a capacity site nearby to offload G9 cells 🙂
Cheers26th November 2006 at 04:03 #45546parsa79Guest
what is the parameter of priority between 900 and 1800 bands?
what is the value of parameter?
thanks alot28th November 2006 at 05:29 #45547parasa79Guest
pardon me i have serios problem in my network please guide me
I’m working in a GSM 900/1800 network . so I have channels in both bands.
I’ll use GSM900 for coverage and GSM1800 for capacity. but there is problem in my network for traffic .i explain in last mesage for you.may i ask you send for me the parameters of both bands?
how can i tune them?
best regards29th November 2006 at 09:04 #45548TomarGuest
OK give me your email adress and i will give you some examples for HCS settings.30th November 2006 at 07:22 #45549pixGuest
multiband settings are quite complex to set, but it’s not all about priority. You have to set HO Margin, cell reselect offset, rxlev threshold for entry in 1800 cells, etc…3rd December 2006 at 06:10 #45550Ravi kantGuest
I m working on Nortel system with dual band but single BCCH.
1.My problem is that when my call is on 1800 Rx level goes beyond -90 even in 100 mt radius.
2. HOver doesn’t take place even if the next Rx level is -48…If hover is there it is very late. And the site hands over preferably first to another 1800 site even it is quite far away.3rd December 2006 at 06:56 #45551Ravi kantGuest
it was quite informative to read all the Q n A regarding the dual band….
Tomar ….could u pls send those HCS n parameters’ settings to me also. As I told in my previous post I m wrkng on Nortel system and I m having serious problems esp in hading over ..which is very- very late . The call gets dragged and it creates unnecessary interference.
Also when I m getting an 1800 site radiated its first E1 ie 900 E1 goes down…..I don’t understand this………..pls help6th December 2006 at 13:13 #45552TomarGuest
Hi Ravi kant,
sorry I’m working with Siemens.7th December 2006 at 08:11 #45553Ravi kantGuest
thnaks for the considerationn Tomar ……..but u can help my question in general if not vendor specific?10th December 2006 at 00:21 #45554pixGuest
it seems that your threshold of emergency handover due to low rxlev is set too low in the DCS1800 cells. Can you try to increase it by 6dB or 8dB ?
Second thing, you should check your neighbor lists settings : do you allow inter-band measures ? meaning : is a mobile allowed to measure cells that belong to a different frequency band ? (there is actually such a parameter)
finally, you should check the margins that are used in the “cell ranking” (Link factor, HO_margin_lev).. this is maybe vendor’s dependant, but those are usually parameters set per adjacency, and that is used to filter out target cells.
let us know how it gos and good luck 😉
pix10th December 2006 at 11:11 #45555parsa79Guest
i have sent several message about my network problem
i have dual network 900/1800
and there is a site with this config 900(666)/1800/(444).when i want to dial in the 1800 band i can not do it and the anten of my ms would lost and when anyone want to call me this announce would listen: the sub is out of coverage area .
if anyone has such exprince please help me .and please send for the parameters of bts and ho and adjc in the 900/1800 netword
for everyone help me and guide me for solving my problem
bye10th December 2006 at 18:08 #45556Valerijs to parsa79Guest
I see your problem but does not understand your config.Do you have BCCH on both band? Then check if 1800 have SDCCH channels.If not then the q. : where is the MS in idle mode? 900mhz?