5G NR Logical, Transport and physical Channels DL UL functions mapping

5G NR Logical, Transport and physical Channels DL UL functions mapping

Channels carry control information and user data. Basically, 5G NR Logical Transport and physical Channels mapping and functions are almost similar to lte.

5G NR Logical Channels

A logical channel is defined by the type of information it carries. We can divide logical channels into two groups:

1. Control Channel which carries control and configuration information.
2. Traffic Channel which carries only data traffics.

Functions of Logical Channels

PCCH (Paging Control Channel): This channel is used for paging of devices whose location is not known to the network on cell level. So, paging messages need to be sent on multiple cells. In case of no-stand alone 5G deployment, there will be no PCCH.

BCCH (Broadcast Control Channel): Like lte it will broadcast all the system information from the network to all the devices.

CCCH (Common Control Channel): Used for carrying common signaling during random access procedure.

DCCH (Dedicated Common Control Channel):  It carries dedicated control information from UE to the network and vise-versa. These information are for individual configuration.

(DTCH)Dedicated Traffic Channel: This channel carries user data from the network to UE and vice-versa.

5G NR Transport Channels

A transport channel is defined by how and with what characteristics the information is being transmitted over the radio interfaces. Basically, the data from the upper layer (or MAC) given to the physical layer is referred as transport block(TB). Each transport block is associated with Transport format (TF). TF specifies that how the TB should be transported over the radio interface. The TF information includes antenna mapping, size of Transport block, modulation and coding scheme etc.

Functions of New RAN Transport Channels

BCH (Broadcast Channel): The BCH carries Master Information Block (MIB). It has fixed transport formt defined by the spec. Basically, BCCH is mapped to BCH and BCH is mapped to PBCH for MIB.

PCH (Paging Channel): It carries paging information received from PCCH logical chnnel.

DL-SCH (Downlink Shared Channel): DSCH is the main transport channel. It will carry user data from network to the devices in NR. It also carries part of the BCCH information such as SIB1 and SIs.

UL-SCH (Uplink Shared Channel): Carries Uplink user data from device to network.

5G NR Physical Channels

The physical layer is responsible for modulation, demodulation, coding scheme, physical layer hybrid-ARQ and multi antenna mapping. It also maps signal to the appropriate resource blocks.

PDSCH (Physical Downlink Shared Channel): It carries the user data from network to devices. It also carries paging information, random access response message and some part of system information such as SIB1, SIs etc.

PUSCH (Physical Uplink Shared Channel): It carries the uplink data from user devices to the network.

PDCCH (Physical Downlink Control Channel): PDCCH carries scheduling related information for downlink as well uplink in the form of DCI.

PUCCH (Physical Uplink Control Channel): PUCCH carries HARQ acknowledgement and  channel state information. It also carries request for uplink grant.

5G NR NSA ENDC Dual Connectivity Signaling end to end attach Call flow.