UMTS notes
Contents
RRC states
(In order of increasing power consumption)
| Idle | |
|---|---|
| URA_PCH / Cell_PCH | The UE is listenning on PCH (Paging Channel), and can't transmit. Listenning for URA PCH in case of fast mobility, Cell PCH otherwise. |
| Cell_FACH | Uses (common) FACH channel for transmission and RACH for reception. |
| Cell_DCH | UE communicates other DCH (dedicated channel). |
Routing areas
(Network is hierarchical).
- URA (UTRAN Routing Area) = group of cells
- RA (Routing Area) = group of URAs
- LA (location area) = group o
Channels
Mobility management
- cell reselection when UE is in Idle or FACH mode
- Redirection: send the UE from connected to Idle mode (for example for CSFB)
- handover: connected procedure, that is UE is in Cell_DCH state.
- Soft handover (SHO): between "adjacent" cells, same frequency, you stay connected to both cells during transition.
- softer handover => different sectors of a given nodeB
- IFHO (Inter-Frequency). NB: Hard handover (HHO) is the same.
- IRAT (Inter Radio Access Technology, e.g. from 3G to 2G)
- IRAT HO: for CS
- Service-based: speech-RAB to GSM
- IRAT Cell: for PS
- IRAT HO: for CS
- Soft handover (SHO): between "adjacent" cells, same frequency, you stay connected to both cells during transition.
- Inter MSC
- Is there something specific to HSDPA / Dual carrier mobility ???
NB: soft and IFHO can be inside one RNC (intra-RNC) or between two RNCs (inter-RNC).
Question: what happened during a multirab isho ?
Directed retry: not a handover per se, but the network refuses the RAB establishment with a cause "directed retry", and sends the UE to the GSM layer. NB: this is a "blind" redirection, there's no measurement before directed retry, and thus no guarantee that the GSM layer can establish a RAB.
Another view (to be merged with previous one)
- Intra-RNC
- Intra nodeB
- inter nodeB
- SHO
- Internal inter-RNC
- HHO
- SHO
- External inter-RNC
- SRNC relocation
- Inter-MSC
- Inter-system
