NG-RAN and 5G-NR
Description
This book describes the architecture of the NG radio access network and the 5G-NR radio interface according to the 3GPP (3rd Generation Partnership Project) specifications. The overall architecture of the NG-RAN, including the NG, Xn and F1 interfaces and their interaction with the radio interface, are also described. The 5G-NR physical layer is mainly connected by implementing antennas, which improves transmission capacity. 5G-SA deals with the 5G Core network.
In the 5G-SA model, the mobile is attached to the 5G Core network through NG-RAN. The book explains radio procedure, from switching on a device to establishing a data connection, and how this connection is maintained even if mobility is involved for both 5G-SA and 5G-NSA deployment. NG-RAN and 5G-NR is devoted to the radio access network, but mobile registration, establishment procedures and re-establishment procedures are also explained.
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Content
- Cover
- Half-Title Page
- Title Page
- Copyright Page
- Contents
- Preface
- 1. NG-RAN Network - Functional Architecture
- 1.1. Functional architecture NSA/SA
- 1.1.1. Option 3
- 1.1.2. Option 4
- 1.1.3. Option 7
- 1.2. Description of the NG-RAN network
- 1.2.1. The NG-RAN
- 1.2.2. AMF (Access management and Mobility Function)
- 1.2.3. SMF (Session Management Function)
- 1.2.4. UPF (User Plane Function)
- 1.3. Functional separation between the NG-RAN radio interface and the 5G core network
- 1.3.1. Mobile identities
- 1.3.2. Mobile mobility
- 1.4. Scheduling and QoS
- 1.4.1. Scheduling
- 1.4.2. Support for quality of service on radio link
- 1.5. Security architecture
- 1.6. Network slicing
- 1.7. References
- 2. NG-RAN Network - Protocol Architecture
- 2.1. The protocol architecture of the radio interface
- 2.1.1. Protocol stack on the Uu interface
- 2.1.2. The protocol architecture on the Xn interface
- 2.1.3. Protocol architecture on the F1 interface
- 2.1.4. Protocol stack on the NG interface
- 2.2. Procedures on the radio network access
- 2.2.1. XnAP procedures
- 2.2.2. F1 interface procedures
- 2.2.3. NG-AP procedures
- 2.3. Identities of the XnAP and NG-AP application protocols
- 2.4. References
- 3. NG-RAN Network - Procedures
- 3.1. General procedure of the 5G-NSA mode
- 3.1.1. LTE search procedure
- 3.1.2. Random access procedure
- 3.1.3. Data transfer
- 3.1.4. Removing a secondary node
- 3.2. General procedures of the 5G-SA
- 3.2.1. Initial random access and beam management procedure
- 3.2.2. Establishment of radio connection
- 3.2.3. Register request
- 3.2.4. The procedure for establishing a PDU session
- 3.3. References
- 4. 5G-NR Radio Interface - The Physical Layer
- 4.1. 5G-NR radio interface
- 4.1.1. OFDM waveform
- 4.1.2. Frequency bands and multiplexing methods
- 4.1.3. NR frame structure
- 4.1.4. NR frame structure in the time domain
- 4.2. TDD mode configurations
- 4.2.1. Static configuration per cell
- 4.2.2. Specific TDD configuration
- 4.2.3. The dynamic configuration of the transmission for a group of mobiles
- 4.3. Physical resource
- 4.3.1. Resource grid
- 4.3.2. Resource bloc and bandwidth part
- 4.4. Physical channels and physical signals
- 4.4.1. Physical signals and reference signals
- 4.4.2. Physical channels
- 4.5. Downlink transmission
- 4.5.1. Synchronization signal
- 4.5.2. Reference signals
- 4.5.3. Physical control and data channels
- 4.6. Transmission in uplink
- 4.6.1. Physical reference signals
- 4.6.2. The physical channel
- 4.7. References
- 5. 5G-NR Radio Interface - Operations on the Frequency Bands
- 5.1. Operations on the frequency bands
- 5.2. Carrier aggregation
- 5.2.1. Carrier aggregation in the FR1 band
- 5.2.2. Carrier aggregation in the FR2 band
- 5.3. Supplementary UpLink (SUL)
- 5.4. Synchronization on the secondary cell
- 5.4.1. Carrier aggregation procedure
- 5.4.2. SUL procedure
- 5.5. References
- 6. 5G-NR Radio Interface - MIMO and Beamforming
- 6.1. Multiplexing techniques
- 6.1.1. MIMO mechanism
- 6.1.2. Baseband beamforming
- 6.1.3. Active antennas and massive-MIMO
- 6.1.4. Antenna systems
- 6.2. Antenna port
- 6.2.1. Downlink transmission
- 6.2.2. Uplink transmission
- 6.3. Uplink Control Information (UCI)
- 6.4. PDSCH transmission
- 6.4.1. Single-CSI and multiple-CSI transmission
- 6.4.2. Codebook configuration
- 6.5. PUSCH transmission
- 6.6. Beamforming management
- 6.6.1. Burst SSB: beam sweeping
- 6.6.2. Cell selection and cell re-selection procedures
- 6.6.3. Beam management
- 6.7. References
- 7. 5G-NR Radio Interface - Bandwidth Part
- 7.1. Bandwidth part
- 7.2. CORESET
- 7.2.1. Configuration of CORESET#0
- 7.2.2. CORESET configuration
- 7.3. BWP switching procedure
- 7.4. References
- 8. 5G-NR Radio Interface - Data Link Layer
- 8.1. SDAP protocol
- 8.1.1. Operations
- 8.1.2. The protocol structure
- 8.2. PDCP
- 8.2.1. Procedures
- 8.2.2. Operations
- 8.2.3. Protocol structure
- 8.3. RLC protocol
- 8.3.1. Operations
- 8.3.2. Protocol structure
- 8.4. MAC protocol
- 8.4.1. Operations
- 8.4.2. Protocol structure
- 8.4.3. Control element
- 8.5. References
- 9. 5G-NR Radio Interface - Radio Access Procedure
- 9.1. System information
- 9.1.1. MIB message
- 9.1.2. SIB1 message
- 9.1.3. SIB2 message
- 9.1.4. SIB3 message
- 9.1.5. SIB4 message
- 9.1.6. SIB5 message
- 9.1.7. SIB6 message
- 9.1.8. SIB7 message
- 9.1.9. SIB8 message
- 9.1.10. SIB9 message
- 9.1.11. Summary
- 9.2. Connection management
- 9.2.1. Paging
- 9.2.2. Connection establishment
- 9.2.3. Activation of security
- 9.2.4. Connection reconfiguration
- 9.2.5. Connection re-establishment
- 9.2.6. Connection release
- 9.3. Measurement configuration
- 9.3.1. Measurement objects
- 9.3.2. The measurement events
- 9.3.3. The filtering of the measurement
- 9.4. References
- Index
- Other titles from iSTE in Networks and Telecommunications
- EULA
1
NG-RAN Network - Functional Architecture
1.1. Functional architecture NSA/SA
Unlike previous generations of mobile networks, the deployment of 5G does not require the simultaneous implementation of the 5G core network (5GC) and the NG-RAN (Next-Generation Radio Access Network).
NSA (Non-Standalone Access) and SA (Standalone Access) are two 5G network models:
- - SA is a completely new core service-based architecture: each radio node is autonomously controlled by the 5G core network. A service-based architecture delivers services as a set of NFs (Network Functions). NFs in the 5G core network are cloud native;
- - NSA relies either on the 4G core network or on the 5G core network. NSA anchors the control signaling to the core network through a radio MN (Master Node). The MN is either a 4G radio node or a 5G radio node. The MN controls an SN (Secondary Node) (4G radio node or 5G radio node) according to the DC (Dual Connectivity) mechanism.
The 5G-SA architecture requires the deployment of a 5G core network connected to the NG-RAN.
The 5G-NSA architecture and the 5G-SA architecture were introduced in Release 15 of the 3GPP standard.
The 5G-NSA configuration implements the MR-DC (Multi Radio Dual Connectivity) architecture.
Figure 1.1. Deployment in the SA mode
Dual connectivity involves two RAN nodes, i.e. master node (MN) and secondary nodes (SN) which has the following features:
- - the MN is connected to the core network for the control plan (signaling) and for the user plane;
- - the SN is controlled by the MN. It is connected to the MN for the control plane (C-plane). The user plane (U-plane) is either connected to the MN or connected to the core network;
- - the master radio access node controls the secondary radio access node and establishes a bearer, if necessary, for the exchange of data between the two radio nodes.
Dual connectivity defines the "Master Cell Group (MCG) bearer" and the "Secondary Cell Group (SCG) bearer".
The MCG carries data that will be transmitted on the radio resources allocated by the MN. In the case of carrier aggregation, the MN supports data on the PCell (Primary Cell) and SCells (Secondary Cells).
The SCG carries data that will be transmitted on the radio resources allocated by the SN. In the case of carrier aggregation, the SN supports data on the PCell and SCell.
The split bearer consists of routing the traffic between the MN and the SN. According to the U-plane termination, the split bearer consists of splitting either the MCG bearer or the SCG bearer.
For E-RABs configured as "MCG bearers", the U-plane termination point is located at the MN.
For E-RABs configured as "SCG bearers", the U-plane termination point is located at the SN.
For the core network configuration, each support (MCG, SCG, split bearer) can end on the MN and/or on the SN. The split bearer is transparent for the core network entities.
Several deployment scenarios (Figure 1.2) have been defined for the 5G-NSA:
- - option 3: the E-UTRAN access network is connected to the 4G core network. The master node is the 4G radio node (eNB - evolved Node B). The secondary node is the 5G radio node (en-gNB). The MR-DC architecture is called EN-DC (E-UTRAN NR Dual Connectivity);
- - option 4: the NG-RAN access network is connected to the 5G core network. The master node is a 5G radio node (gNB - next generation Node Base Station). The secondary node is a 4G radio node (ng-eNB). The MR-DC architecture is called NE-DC (NR - E-UTRAN Dual Connectivity);
- - option 7: the NG-RAN access network is connected to the 5G core network. The master node is a 4G radio node (ng-eNB - next generation eNB). The secondary node is a 5G radio node. The MR-DC architecture is called NGEN-DC (NG-RAN E-UTRAN NR Dual Connectivity).
Figure 1.2. NSA configuration options
1.1.1. Option 3
Option 3 is the non-standalone EN-DC configuration.
Option 3 uses the MN (Master Node) terminated MCG (Master Cell Group) bearer for signaling: the eNB is the master node, and the gNB (gNodeB) acts as the secondary node. The radio access network is connected to EPC.
The 4G base station (eNB) controls the 5G base station (en-gNB) through the X2 interface.
The eNB supports signaling with the MME (Mobile Management Entity) through the S1-MME interface and supports the user plane traffic (MCG bearer) with the SGW (Serving Gateway) entity through the S1-U interface.
The en-gNB base station supports signaling with the eNB. The 5G-NR interface is activated by the eNB over the X2 interface. Once activated, en-gNB controls its own radio resource allocation. The user traffic is either transmitted from the eNB to en-gNB or transmitted from the 4G core network (SGW) over the S1-U interface to en-gNB.
The master node eNB exchanges data in both directions, uplink and downlink, with the mobile.
The secondary node en-gNB allows us to increase both uplink and downlink data rates.
With a DC mechanism, data is transmitted to the mobile according to one of the following variations (Figure 1.3):
- - option 3: in plain option 3, all uplink and downlink data flows to and from the LTE part (MCG split bearer) of the LTE/NR base station, i.e. to and from the eNB. The eNB then decides which part of the data it wants to forward to the 5G gNB part of the base station over the Xx interface;
- - option 3a: both LTE eNG (MCG bearer) and 5G-NR en-gNB (SCG bearer) exchange traffic to the 4G core network directly. This means that a data bearer allocated to a node cannot share its load over the second node. This option does not suit the case of mobile use;
- - option 3x: user data traffic will directly flow to the 5G gNB part of the base station (SCG split bearer). The traffic is delivered over the 5G-NR interface to the device, and part of the data can be forwarded over the X2 interface to the 4G eNB.
Figure 1.3. Secondary node addition - option 3
Option 3 uses the MN terminated MCG bearer for user traffic. The eNB entity splits the S1 bearer into:
- - LTE radio support;
- - NR support.
Option 3x uses the SN terminated SCG bearer for user traffic. The gNB entity splits the S1 bearer into:
- - LTE radio support;
- - NR support.
1.1.2. Option 4
Option 4 relies on the 5G core (5GC).
The gNB acts as an MN; it supports signaling exchange (MCG signaling bearer) with the 5G core network's transport plane through the NG-C interface. The LTE user plane connections go via the 5G-NR through the NG-U interface.
The ng-eNB base station acts as a secondary node. It is controlled by the gNB base station through the Xn-C interface. The ng-eNB is a new generation of the 4G base station.
The gNB controls the ng-eNB through the Xn interface.
The data is transmitted to the ng-eNB entity via one of the following options (Figure 1.4):
- - from the master node gNB, which performs the split bearer (option 4, MN terminated split bearer);
- - from the 5GC network (option 4a, SCG bearer).
Figure 1.4. NE-DC architecture - option 4
1.1.3. Option 7
Option 7 relies on the 5G core (5GC).
The ng-eNB acts as an MN; it supports signaling (MCG signaling bearer) with the 5GC core network's transport plane through the NG-C interface and exchanges data to the 5G core network's user plane through the NG-U interface.
The gNB base station acts as an SN. It is controlled by the ng-eNB base station via the Xn-C interface.
The ng-eNB (4G base station) controls the gNB through the Xn interface.
The data is transmitted to the gNB entity via one of the following options (Figure 1.5):
- - from the ng-eNB base station, which performs a split bearer. This is option 7 (MN terminated split bearer);
- - from the 5G core network. This is option 7a (SCG bearer).
Figure 1.5. NE-DC architecture - option 7
1.2. Description of the NG-RAN network
The NG-RAN provides both NR and LTE radio access.
An NG-RAN node is either a gNB (5G base station), providing NR user plane and control plane services, or an ng-eNB (new generation 4G base station) providing the LTE/E-UTRAN services towards the UE (control plane and user plane).
The NG-RAN ensures the connection of mobiles and the reservation of radio resources between:
- - the mobile and the ng-eNB base station on a single 4G carrier (LTE) or on several 4G frequency carriers (LTE-Advanced);
- - the mobile and the gNB base station on one or more 5G frequency bands (5G-NR).
The gNBs and ng-eNBs are interconnected through the Xn interface. The gNBs and ng-eNBs are also connected, via NG...
