# Jonathan Notes #5

Main reference: [5G NR Logical Architecture and its Functional Split Options](https://bit.ly/2uDv5CW): Your Study Note Hyperlink
Deadline: 11th May 2020

###### tags: `ET6207701`

## 5G New Functional Requirements
### 5G Enablers and Principles
- Modularization
- Network Slicing
- Network Softwarization
- Multi-Access Edge Computing (MEC)

### 5G NR Use Cases

### 5G NR Key Aspects
- Higher frequency operation and spectrum flexibility
- Ultra-Lean Design
- Forward Compatibility
- Duplex Schemes
- Low-Latency Support

## 5G Protocol Stack and its Architecture
### Network Architecture
### User Plane Protocol Stack

- SDAP (Service Data Adaptation Protocol)
- Mapping between a QoS flow and a data radio bearer (Due to new QoS framework)
- Marking QoS flow ID (QFI) in both DL and UL packets ( DL: due to reflective QoS and UL: due to new QoS framework)
- A single protocol entity of SDAP is configured for each individual PDU session, except for DC where two entities can be configured
- PDCP (Packet Data Convergence Protocol)
- Sequence Numbering
- Header compression and decompression: ROHC only
- Transfer of user data
- Reordering and Duplicate detection (if order delivery to layers above PDCP is required)
- PDCP PDU routing (in case of split bearers)
- Retransmission of PDCP SDUs
- Ciphering and Deciphering
- PDCP SDU discard
- PDCP re-establishment and data recovery for RLC AM
- Duplication of PDCP PDUs
- RLC (Radio Link Control)
- Transfer of upper layer PDUs
- Sequence numbering independent of the one in PDCP
- Error Correction through ARQ
- Segmentation and re-segmentation
- Reassembly of SDU
- RLC SDU discard
- RLC re-establishment
- Medium Access Control (MAC)
- Mapping between logical channels and transport channels
- Multiplexing/demultiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels
- Scheduling Information Reporting
- Error correction through HARQ
- Priority handling between UEs by means of dynamic scheduling
- Priority handling between logical channels of one UE by means of logical channel prioritization
- Padding
- Physical Layer (PHY)
- Coding/decoding
- Modulation/demodulation
- Multi -antenna mapping
- Mapping transport channels to physical channels
- and other PHY related functions

### 5G NR Mapping between Logical, Transport and Physical Channels

**No BCCH in 5G NR**

### 5G QoS Architecture
- more granular
- the radio bearers can be handled independently from the CN

### RRC states

### Transmission Structure


### LTE vs 5G NR

## 5G NR Functional Split
- Introduction of midhaul provides more flexibility for transport options
- Control Plane/User Plane split (Vertical split)
- Central Unit/Distributed Unit split (Horizontal split)
- Need software based implementation to support the tehnology