• Service provided by L1 to L2 (MAC). Defined how data is transported.
• Common transport channels (where there is a need for inband identification of the UEs when particular UEs are addressed);
• Dedicated transport channels (where the UEs are identified by the physical channel, i.e. code and frequency for FDD and code, time slot and frequency for TDD).
Dedicated transport channel types are:
• Dedicated Channel (DCH): A channel dedicated to one UE used in uplink or downlink.
Common transport channel types are:
• Random Access Channel (RACH):
A contention based uplink channel used for
transmission of relatively small amounts of data, e.g. for initial access or non-real-time dedicated control or traffic data.
• Common Packet Channel (CPCH):
A contention based channel used for transmission of bursty data traffic. This channel only exists in FDD mode and only in the uplink direction. The common packet channel is shared by the UEs in a cell and therefore, it is a common resource.
The CPCH is fast power controlled.
• Forward Access Channel (FACH): Common downlink channel without closed-loop power control used for transmission of relatively small amount of data.
• Downlink Shared Channel (DSCH):
A downlink channel shared by several UEs carrying dedicated control or traffic data.
• Uplink Shared Channel (USCH):
An uplink channel shared by several UEs carrying dedicated control or traffic data, used in TDD mode only.
• Broadcast Channel (BCH):
A downlink channel used for broadcast of system information into an entire cell.
• Paging Channel (PCH):
A downlink channel used for broadcast of control information into an entire cell allowing efficient UE sleep mode procedures. Currently identified information types are paging and notification. Another use could be UTRAN notification of change of BCCH information.
Transport Channel
