UMTS notes

From Tronche's wiki
Jump to: navigation, search


RRC states

(In order of increasing power consumption)

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


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
  • 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


Personal tools