UMTS Network Basic Strategy

[khurrambilal01]

Hi experts,
I have a few question related to UMTS nework design,

PLMN id for 3G & 2G should be same or different? What is the benefit/loss if we have same/different PLMN ID?
UMTS has separate LACs from GSM? How can we dimension LAC in UMTS network (Same as GSM or different?).
What should be cell reselection strategy for 3G -> 2G and vice versa if 3G coverage is present?
Handovers from 2G to 3G should be enabled or not and what should be the criteria? What is the loss if its enabled?

Thanks for sharing knowledge!

[khurrambilal01]

Experts please help!

[Muhammad Imran Rafique]

Hi Khurram Bilal,
I am working on a network having high utilization on 2G/3G & LTE is just launched.

1. CORE experts can answer with pros and cons, i think PLMN related info is saved on SIM cards so it should be same. Other wise it will be problem in network selection.
2. Here two strategies are followed.
a) 2G/3G has different LACs, so based on BSC/RNC capability you can dimention irrespective of technology dependency.
b) if 2G/3G has same core then there is possibiity to use on LAC for both technologies.

3) Cell Reselection (2G to 3G), is normally based on EcNO only i.e lets say FDDQMIN is -12dB then irrespective of RSCP we will select 3G cell. FDDQMIN can be further tuned on cell basis normally -8,-12,-14,-16 values are used. Here we need to be very careful as this cell reslection will be applicable to EDGE/GPRS users as well in active mode. So same paramters are used for 3G cell evaludation during data mode.

Cell Reselection (3G to 2G), is normally based on RSCP OR EcNO values. Lets say either my EcNO drops from a certain level OR RSCP drops from certain level. I will start searching 2G cells and then based on relational offset i will furhter camp-on on 2G cell. Normally SRATsearch is -16/-18 dB for EcNO and RSCP is -112dBm.

4) 99% of networks dont use handover from 2G to 3G, the reason is very simple. For CS user if someone come to 2G for speech then he should continue here till end. For PS users cell reselection is always active and criteria is exactly the same as we have for idle mode cell reselction.


Hope it will clear some basic startegies for 2G/3G networks.

BR//
Imran