NR-Logical Channels,Transport Channels and Physical Channels Mapping

In 5G New Radio (NR), the communication between the network and user equipment (UE) involves the use of logical channels, transport channels, and physical channels. Let's delve into each of these components and how they are mapped in the NR protocol stack.

1. NR Logical Channels:

Definition:
Logical channels represent specific information flows at the radio interface. These channels are classified based on the type of information they carry and the protocol layer they belong to.

Types of Logical Channels:

1. Broadcast Channels (BCH):
   • PBCH (Physical Broadcast Channel): Carries system information for cell identification and synchronization.
2. Downlink Shared Channels (DL-SCH):
   • PDSCH (Physical Downlink Shared Channel): Carries user data and higher-layer signaling.
3. Uplink Shared Channels (UL-SCH):
   • PUSCH (Physical Uplink Shared Channel): Transmits user data.
   • PUCCH (Physical Uplink Control Channel): Carries uplink control information.
4. Common Control Channels:
   • PRACH (Physical Random Access Channel): Used by UEs to request resources.
   • SS/PBCH Block: Contains synchronization and cell-specific information.
5. Dedicated Control Channels:
   • DCI (Downlink Control Information): Carries control information for PDSCH.

2. NR Transport Channels:

Definition:
Transport channels are used to carry data between different protocol layers within the radio protocol stack. They are the interface between the logical and physical channels.

Types of Transport Channels:

1. Broadcast Channel:
   • BCH (Broadcast Channel): Transmits system information. The information is transported by the PBCH (Physical Broadcast Channel).
2. Downlink Shared Channels (DL-SCH):
   • PDSCH (Physical Downlink Shared Channel): Carries information from the DL-SCH.
3. Uplink Shared Channels (UL-SCH):
   • PUSCH (Physical Uplink Shared Channel): Carries information from the UL-SCH.
   • PUCCH (Physical Uplink Control Channel): Carries information from the UL-SCH.
4. Random Access Channel:
   • PRACH (Physical Random Access Channel): Carries information from the RACH.

3. NR Physical Channels:

Definition:
Physical channels represent the actual transmission of information over the radio interface. They define the format and structure of the radio signals.

Types of Physical Channels:

1. Broadcast Channel:
   • PBCH (Physical Broadcast Channel): Transmits the broadcast channel information.
2. Downlink Shared Channel:
   • PDSCH (Physical Downlink Shared Channel): Transmits user data and higher-layer signaling.
3. Uplink Shared Channel:
   • PUSCH (Physical Uplink Shared Channel): Transmits user data.
   • PUCCH (Physical Uplink Control Channel): Transmits uplink control information.
4. Random Access Channel:
   • PRACH (Physical Random Access Channel): Transmits random access requests.

Mapping Between Logical Channels, Transport Channels, and Physical Channels:

1. Logical to Transport Channel Mapping:
   • Logical channels are mapped to transport channels based on the type of information they carry.
   • For example, DL-SCH logical channel information is mapped to the PDSCH transport channel.
2. Transport to Physical Channel Mapping:
   • Transport channels are mapped to physical channels that define how the information is transmitted over the air interface.
   • For example, the PDSCH transport channel is mapped to the PDSCH physical channel.
3. Control Information:
   • Control information, such as Downlink Control Information (DCI), is exchanged between the network and the UE through dedicated control channels.
4. Dynamic Mapping:
   • The mapping can be dynamic, with the network adjusting the allocation of resources based on the communication needs and conditions.

Understanding the mapping between these channels is crucial for efficient communication in a 5G NR network. The specifics of this mapping may vary based on the NR deployment scenario, frequency band, and other network-specific parameters.