Notes on UMTS 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
|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 ?
Mapping of the channels
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