Most DL data traffic is carried on the Down Link Shared Channel (DL-SCH) transport channel and
its corresponding Physical Downlink Shared Channel or PDSCH
are offered by the MAC layer)
Different kinds of data transfer services as offered by MAC. Each logical
channel type is defined by what type of information is transferred
Control Channels (for the transfer of control plane information)
Traffic Channels (for the transfer of user plane information)
CONTROL LOGICAL CHANNELS (C-Plane information)
– Broadcast Control Channel (BCCH)
- System information
– Paging Control Channel (PCCH)
- Paging information
– Multicast Control Channel (MCCH)
- Point-to-multipoint channel for MBMS control
information
– Dedicated Control Channel (DCCH)
- Unicast control channel
– Common Control Channel (CCCH)
- Point-to-multipoint channel used before RRC
connection established
TRAFFIC LOGICAL CHANNELS (U-Plane information)
– Dedicated Traffic Channel (DTCH)
- Unicast traffic channel
– Multicast Traffic Channel (MTCH)
- Point-to-multipoint channel for MBMS traffic
TRASPORT CHANNELS (How different type of information is going to transferred over the Air Interface) The physical layer offers information transfer services to MAC and higher layers. The physical layer
transport services are described by how and with what characteristics data are transferred over the radio interface:
Broadcast Channel (BCH) characterized by:
- fixed, pre-defined transport format; requirement to be broadcast in the entire coverage area of the cell.
Downlink Shared Channel (DL-SCH) characterised by:
- support for HARQ;
- support for dynamic link adaptation
- possibility to use beamforming;
- support for both dynamic and semi-static resource allocation;
- support for UE discontinuous reception (DRX) to enable UE power saving;
- Support for MBMS transmission.
NOTE: The possibility to use slow power control depends on the physical layer.
Paging Channel (PCH) characterised by:
- support for UE discontinuous reception (DRX) to enable UE
power saving (DRX cycle is indicated by the network to the
UE);
- Requirement to be broadcast in the entire coverage area of
the cell;
- mapped to physical resources which can be used
dynamically also for traffic/other control channels.
Multicast Channel (MCH) characterised by:
- requirement to be broadcast in the entire coverage area of the cell;
- support for MBSFN combining of MBMS transmission on multiple cells;
- support for semi-static resource allocation e.g. with a time frame of a long cyclic prefix.
Physical Channels Control Related Information: CFI – Control Format Indicator is transmitted in PCFICH
HI - HARQ Indicator is transmitted in PHICH
DCI – Down Link Control Indicator is transmitted in PDCCH
UCI – Uplink Control Information sent on PUCCH/PUSCH