Notes on UMTS channels
Contents
The channels
The 9 Logical channels
They are divided in control channels (for the control plane) and traffic channels (for the user traffic).
The 6 control channels
This is were exchanges in the control plane take place
Acronym | Channel name | Broadcast / Unicast | Direction | RLC mode |
---|---|---|---|---|
BCCH | Broadcast Control Channel | Broadcast | DL | transparent |
PCCH | Paging Control Channel | unicast | DL | |
CCCH | Common Control Channel | unicast | both | |
DCCH | Dedicated Control Channel | unicast | both | AM or UM |
DTCH | Dedicated Traffic Channel | unicast | both | All modes |
Channels can be broadcast (traffic is sent to every terminal listening), or unicast (trafic is targeted at some particular device, either the UE or the node B.
Directions are: DL = download (from network to terminal), UL = upload (from terminal to network), or both.
The 5 transport channels
Acronym | Channel name | Direction | |
---|---|---|---|
BCH | Broadcast Channel | DL | Used to broadcast some technical, service informations. |
PCH | Paging Channel | DL | Use by the network to communicate with the UE before the UE request communications. |
RACH | Random Access Channel | UL | Used for bidirectionnal communications (control and small data) when the UE doesn't have a dedicated channel. |
FACH | Forward Access Channel | DL | |
DCH | Dedicated Channel | both | Used when "heavy" communications take place, notably CS and PS in the user plane. |
What about HS-DSCH and E-DCH ?
Physical channels
Mapping of the channels
References
- http://samiramberkar-tutorials.blogspot.com/2010/06/umts-13.html
- http://wush.net/trac/rangepublic/wiki/DecodingUMTS
- http://my.safaribooksonline.com/book/networking/wireless/9781602670044/wcdma-logical-transport-physical-channel-mapping/ch04
- http://www.radio-electronics.com/info/cellulartelecomms/umts/umts-wcdma-channels.php