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Reply To: 3G frequency plannig

#69267
Optimustron
Guest

Rex,
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,