I’m working in 3G Huawei.So,
related to HO 3G to 2G, and its selection/reselection :
First of all, we should make a proper adjacency with 2G Cells. Ensure that the LAC of the adjacent 2G (neighbor) must be enlisted in RNC and vise versa (RAC 3G is also listed in OMC 2G). If both requirements are not reached, then there will be no HO happen between 3G-2G.
In 3G Huawei, each node B has its parameter that arrange the HO, at what level of RSCP the HO happens. So does reselection.
Remember, 3G capacity is based on CE (channel elements).
We know that 3G is focused on Packet data services which mean, most its capacity is for Data, not voice. We can also see the RNC license, the maximum voice Erlang could be handled by its RNC.
So how to control it? For reselection, check LST UCELLINTERRATHOCOV, check parameter Inter-RAT R99 PS measure start RSCP THD[dBm], Inter-RAT R99 PS measure stop RSCP THD[dBm], for HSDPA , and also for CS selection.
This parameter indicates whether you want the reselection from 3G to 2G happens faster (at strong 3g signal level, HO/reselection happens), or slower (keep the UE always attach to 3G even at the weak level RSCP).
Why most of vendor don’t implement 2G ==> 3G Handover? From my point of view :
The principal understanding of Capacity between 2G and 3G is different. As I know, If one UE attach on 3G and make a call in 3G, that it will spend 1 CE. How about alot of UE use 3G for call? Instead, we should remember about the throughput in 3G (SF8,SF16,SF32). The smallest SF is defined (e.x SF8), the higher throughput will be get and the fewer UEs can attach to 3G. The higher throughput, the higher CE (CHannel elements) are needed. Please correct me if I’m wrong.
Well, that’s what I know, please feel free to discus about 3G 🙂 It’s interesting topic to discus 🙂