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Hi all!
How can we dimension location area in a network which have both combined BCCH/SDCCH and non-combined BCCH/SDCCH?
Can you help me?
Thank you very much.Well, given that you have both combine and non-combine CCCH, you should consider the worst case scenario i.e. Combine Common Control Ch.
Hi Quochv,
The best way to start dimensioning your LACs is to have whole BSC(s) in one LAC (may be 1 or 2 or 3) depending upon your signalling..is it 64K or more or less.
If you start with above method, then you can see the possible points where you need to re-parent your sites or possbily increase the sdcch channels for boundary cells to define a better LAC area.
Please revert incase of any clarifications if required.
Best regards,
Garry !!
Thank you Garry and Tracy!
If I have that network activitied but I want to impove better paging, what should I do? Suppose this network have 3 BSC, each BSC service a LA.
Can you tell me more particular?
Thanks.
I think the starting point would be to establish the paging capacity of your Lacs. The evaluate the paging load at BH and size your lacs accordingly.
To get the paging capacity consider that in one hour you have a maximum of 3600 / 0.235 *(9 – BS_AG_BLKS_RES) *pag_msg_per_pag_chn *eff% in uncombined BCCH. replace 9 with 3 for combined in the above formula.
3600/0.235 is the max ccch blocks you may have in an hour given the duration of the tdma frame is 235 mS
9 – BS_AG_BLKS_RES is the total PCHs you get from the radio TS when uncombined
pag_msg_per_pag_chn is the paging channels per paging message depending on the paging mode implemented ie imsi-imsi, tmsi-tmsi etc. Usually there are either 2 or 3 paging messages per paging channels
eff% is the efficiency level to which you wish to load your paging channels. 80% is a safe limit if you can handle the signalling traffic that results from redifining many LACs
Compare these capacity thresholds against the BH paging messages as recorded by the omcr counters and make your decision on the size and number of LACs you need
Can e n body tell me this capacity u r talking abt this 51 multiframe is for one BTS or for 1 BSC.
in 1 small town i have 5 sites. i want to add a 6th BTS at the center of the town in a new BSC defining a different LAC; meaning that the 5 sites with LAC 1 will surround the 6th BTS with LAC 2.
how should i dimension.ishmael,
don’t do that !! it’s a bad choice. Keep the same LAC over the whole village.
If you go on with your idea:
– lot of location updates –> you need to add more SDCCH timeslots on all BTS (1 -> 6)
– inter BSC HO are slower and usually are restrictive (not all causes available ? it’s vendor dependent)
– risk of some pagings repetitions over the whole MSC (if one MS is chaging LAC often, it might miss a paging, and the MSC might repeat it in all cells of MSC)
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