- This topic has 6 replies, 1 voice, and was last updated 8 years, 2 months ago by Optimustron.
23rd September 2013 at 21:34 #69265RexGuest
why some operator use only one 5MHz for three cells even if they have 15MHz spectrum? And, how the planning is done in order to minimize interference?
Rex24th September 2013 at 05:10 #69266pixGuest
If they are only using 5MHz, it’s probably because they don’t need (yet) to provide that much throughput to subscribers just now.
IN terms of hardware, they would need much more hardware per node B in order to use their 15MHz. Hoever, as far as I know, using 5 or 10 MHz uses about the same amount of boards in a node B.
Regards27th September 2013 at 03:19 #69267OptimustronGuest
The operator only use only one 5 Mhz channel because surely is a version of CDMA, I think because of the bandwidth is a 3G carrier, then it is WCDMA for this kind of systems, CDMA in general the way to avoid interference is by means of SC or SCRAMBLING CODES, they’re different for each sector in the system and it provides the way to distinguish between cells and decode without problems a call, in WCDMA there are 512 SC, this is a lot of codes then it’s easy to have good separation between sectors or cells and interference is minimized. If you use different frequencies you need to make a HHO or Hard Handover to change between cells then increasing the drop call probability instead when you use the same frequency you have SHO or Soft Handover and then the probability of drop call is less. When to use another frequency well it’s how Pix explains you, it’s mainly a matter of capacity all the time. The planning is easy but the optimization is hard because you have a lot o types of congestion, like codes, power, channel elements and Iub, you need to fight with the correct level of SHO%, pollution, interference and cell breathing for example, there are other things like DRX Cycle for Paging, URA-DCH-PCH state, etc. Best regards,6th October 2013 at 22:15 #69268RexGuest
Thanks Pix, Optimustron22nd October 2013 at 21:25 #69269RexGuest
I have another issue regarding 3G and Lte implementation. If there are 10 MHz 900MHz and 10 MHz 1800 MHz available, 5MHz reserved for 3G in 900MHz and 5MHz for Lte in 1800MHz, the other 5MHz in 900 and 5MHz in 1800 for 2G, in that case we have to replan frequencies for 2g existing cells. Do you have such a case of 2g frequency replanning? What is your aproach in that case? I was thinking using multiband cell planning, because of limited number of channels in 900 and 1800. For the single band cell planning I think is to tough. Any Idea?
Rex27th October 2013 at 12:18 #69270RexGuest
No one?29th October 2013 at 00:48 #69271OptimustronGuest
At this time we are very busy excuse me, I’ ll try to explain briefly, however Isn’t easy. The best case to avoid change band is to put GSM in the same band, then you will have an easy planning in GSM, however it depends on your percetages of penetration of each technology. If you have a mature UMTS & LTE networks its better to have limited coverage because you can contol better tbe interference at higher ftequency because you have less propagation than in lower frequencies, however you have better penetration because of wavelength. That are tbe base, however the costs play another point of view, you’ll need less sites with 900 Mhz to cover the same area.
If are with the situation that you told us there is no opportunities selecting equipmets and you need to work as you told us, i.e. multiband cells in GSM, by the way you must to work with multibands and multitechnology.
If you need something more specific tell us but give us some more details. Besr regards,