- This topic has 73 replies, 1 voice, and was last updated 10 years, 11 months ago by yonatan bekele.
31st December 2007 at 21:16 #48810pixGuest
antenna diveersity can be either DL TX, or UL RX, or both. It just means you have two signals transmitted from different antennas, or different branches.
If you have a cell connected to a crosspolar antenna, it is probable that each branch will be used to receive the UL signal. This is UL space diversity. You have one branch with RX-A and one branch with RX-B.
The signal FROM the BTS is transmitted on only one branch. There is only TX-A.
If you want to use DL TX diversity, it means you want to use the second branch to send TX-B.
What do you need to do ? Duplex the RX-B signal and the TX-B signal. Most probably, it means you need :
1. a new type of TRX (with 2 TX output)
2. to re-cable TRX-ANC jumpers
Beware that when using the 2 TX diversity, you’ll need to balance your path loss in uplink as well. You must increase sensitivity of the UL path, either with TMA or with 4 RX diversity.
Pix9th January 2008 at 10:01 #48811deep_kGuest
hi pix !
i have a situation described as under …….. need ur precious comments for the same:
i have defined one new BSC ( with a particular LAC ) in the MSC
after that i have defined a site in OMCR with a cell Id say 123 …… but these sectors with cell Id 123_1 , 123_2 , 123_3 have not been defined in MSC .
now my question is whether there will be any MOC or MTC calls possible in this sectors or not ?
deep_k9th January 2008 at 11:43 #48812AbdelGuest
NO MO but MT is ok cuz the MSC will not accept unkown cells to make MO calls.9th January 2008 at 13:15 #48813pixGuest
i would trust abdel on this, because i have zero experience with MSC…
but just to make it clear :
BTS ID = 123
CELL ID = 123_1, 123_2, 123_3
Cells are defined in OMCR but not in MSC.
Why would anyone do that ?9th January 2008 at 13:29 #48814deep_kGuest
hi pix n abdel
actually i had a case where one vendor’s BTS was being swapped with another vendor’s BTS with the creation of a new BSC and the switch guy did the mistake.
could u pls support the logic how MTO will happen and MO will not happen.
I say that MTO will not happen since paging can not be done when the cell Id is not defined in the switch ??9th January 2008 at 21:17 #48815AbdelGuest
I have a problem on posting on this thread. Is it related to the lenght of the message or something like that10th January 2008 at 10:07 #48816pixGuest
it is because you are using forbidden associations of letters …
for example if you write “A” attached with “NAL”, your post will be rejected :)) that happens a lot because the word :
An (llkklk) alysis
cannot be written. Use “investigation” instead 🙂10th January 2008 at 12:45 #48817AbdelGuest
The main reason behind the Cell global indenfication (CGI) is the MOC routing and not MTC and for billing purposes. When you get into an area where it is covered by a BTS which it’s CGI is not defined in the MSC then you will not able to make calls (but remember you are registered in the VLR), the reason you can not make A call the is routing table is not defined and this can be done only when defining the CGI at the MSC side. A good example which you can compare is the trunk number in fixed switching the purpose for it is routing and billing nothing else. Also another example is, you want the subscribers in a certain area to have access to specific number like 120, or you want some subscribers in some location to have different format of dialing, this can be done in the MOC digit checking.
As far as I know MTC is not controlled as long as it is from a legal source.
So are you working at the NSS side? If not you ask the NSS engineer what parameters he inputs when configuring the CGI? This probably includes the MOC digit table number. By the way have you experience this case that both MOC and MTC were not possible while the CGIs were not defined in the MSC? Is my explanation reasonable what I am saying just my experience. Thanks
Remember CGI= MNC+MCC+LAC+CI10th January 2008 at 21:48 #48818ModeratorGuest
Pix is right. This forum has a very string filter. It can be a bit annoying, but I hope you agree that, compared with others, this is a very focussed forum.
I take your point about “analysis” and I have removed that word from the list.11th January 2008 at 06:59 #48819deep_kGuest
hi abdel , pix
thanx for nice comments !
will get back on the same topic once i collect some more info from the engineers in the field who attended the same.
i have one more query :
According to erlang table :
say for 2% GOS and 10 TCH channels the traffic catered will be 5.084.
for the same 10 TCH channels and GOS as 5% the traffic catered will be 6.216.
my quesiton is as the GOS increases why the traffic taken is high ?
supporting logic ?
i know GOS as : it is the probability of getting a call blocked in the first attempt in the busy hour. If it is 2% …….. means 2 calls out of 100 will be blocked in the busy hour due to the lack of resources ( RACH , PCH , SDCCH or TCH ?? …… which one in specific or all ?????///// )
How the availability of resources increases with the increase in GOS ?11th January 2008 at 10:02 #48820pixGuest
the traffic offered increases if the GOS increases, that’s normal. Let me explain:
a cell with 3 TRX (21 TCH timeslots) :
at 2%GOS, traffic offered (or capacity) = 14 erlangs.
at BH, it means 2% of 14 erlangs are rejected and 98% carried.
at 50% GOS, capacity = 36 erlangs (i’m just imaginary value, ok ?)
it means at the BH, 50% of the 36 erlangs are rejected, and 50% are carried (18 erlangs).
The capacity is different than the actual traffic being carried, but you understand that the site, with this GoS, is designed to cover an area generating 36 erl at BH.11th January 2008 at 17:51 #48821TNSGuest
“… my quesiton is as the GOS increases why the traffic taken is high ?…”
I hope you know that in fact you decrease the traffic taken by decreasing the GOS…
I mean: with 10 FR TCHs the absolute maximum of the traffic taken is … 10 erlang ( 20 Erl for 10 DR TCHs ). It’s sure – the blocking rate will be 100%.
When we decrease the Block rate ( to fit in the license agreement , let’s say )we decrease the traffic taken.
I want to mension that this Erlang tables are for FR TCHs only.
I think the tables don’t take into account the soft blocking…
TNS11th January 2008 at 18:10 #48822TNSGuest
I’m sorry I forgot this one:
“… means 2 calls out of 100 will be blocked in the busy hour due to the lack of resources ( RACH , PCH , SDCCH or TCH ?? …… which one in specific or all ?????…”
First at all it’s not obligatory to have maximum block rate during the BH…
Usually we speak about TCH blocking…
There is SDCCH blocking rate ( Erlang table is valid – SDCCH/8 = 8 channels ).
RACH and PCH blocking – never heard. If BCC ( not CBC ) configuration – you need a new site ( several 8/8/8 sites in fact 🙂 ) because of the RACH or LA split because of PCH…
TNS16th January 2008 at 11:18 #48823ANTGuest
From “RACH and PCH blocking – never heard.”,
I would like to know that how to detect the RACH and PCH blocking?
Thanks in advance.16th January 2008 at 12:21 #48824deep_kGuest
I have also not heard about RACH and PCH blokcing ……
but my question is that according to 2% GOS say …. 2 calls in the busy hour will get blocked due to the no resources available ………..
which resource is this?
RACH , PCH , SDCCH , TCH ??
Is it a specific resource or all are considered in the definition of GOS ?