Datang Cup (record

• RAN – Radio Access Network
• MCG - Master Cell Group
• SCG - secondary cell group
• CPRI - Common Public Radio Interface
• REC - Wireless Equipment Control
• BBU - indoor baseband processing unit
• RRU - remote radio frequency module
• CU - centralized unit
• DU - Distribution Unit
• AAU - Active Antenna Processing Unit
• split bearer - split bearer
• CP - Control Plane
• eMBB - Enhanced Mobile Broadband
• mMTC - Massive Low Power Connections
• uRLLC - Low Latency Highly Reliable Connection
• MANO - Management and Orchestration
• VNF – Virtual Network Function
• PTN - Packet Transport Network
• OTN - Optical Transport Network
• MEC - Mobile Edge Computing
• RRH－Remote Radio Head

5G Network Architecture and Networking Deployment 

• 5G system consists of access network (AN) and core network (5GC)
• The 5G mobile communication system includes 5GC and NG-RAN. 5G base station - gNB, 4G base station - eNB, 4G enhanced base station - ng-eNB, base station accessing 4G core network - en-gNB.
• The 4G mobile communication system includes EPC (4G core network) and E-UTRAN.

5G network overall architecture composition

• 5G core network and 5G access network are connected through NG (5G interface) to realize control plane and user plane functions
• The 5G radio access networks are connected through the Xn interface to realize the functions of the control plane and the user plane
• MEC is a key technology supporting the operation of 5G systems

4G and 5G system architecture comparison

Core Network Architecture Evolution

• Analog communication (low security) → digital communication → Internet (full IP) → SDN/NFV [software-defined network/network function virtualization] (network slicing technology-service-based network architecture, micro-service; the number of network elements has increased significantly ; network element virtualization)
• 3G-4G cancels the CS domain and only retains the PS domain
• The 5G core network is implemented based on SBA (Service Based Architecture)

Main network element functions

Terminal home location and visiting location: if they are the same address, it is not roaming, otherwise it is roaming

• The information interaction between 5G network functions can be expressed in two ways, one is based on service representation; the other is based on point-to-point representation.

• The base station network element function of the 5G wireless access network is divided into CU and DU

UPF (User Plane Function)

• Local mobility anchor for handover between gNodeBs
• External PDU session point connected to mobile communication network
• As a node between the access network and the external data network, the node connecting the mobile communication network and the external session
• Routing and forwarding of data packets→Uplink traffic verification (QoS flow mapping)

SMF (Session Management Function)

• Session establishment, modification and deletion
• Assign and manage IP addresses
• Select the functions that control the user plane

AMF (Access and Mobility Management Function)

• Based on non-access layer (NAS signaling) encryption and integrity protection, user authorization and key management
• Mobility Management at Non-Access Stratum (NAS)
• SM message transmission between UE and SMF

gNB/en-gNB

CU-C (to complete the function of the control plane)

• Interface management: Xn/NG/F1/E1 and other interface link management, interface message processing and data processing
• Connection management: single connection, dual connection, multi-connection and D2D
• Load balancing within and between systems
• Dynamic management of slice resources within and between systems

WITH D

• Packet Processing and Transformation
• Resource Scheduling, Transmission Mode Switching, Channel Mapping
• Signal transceiver

Understanding NE Interface Relationships

NG interface

The NG interface is the interface between the 5G access network and the 5G core network, and is divided into a control plane protocol stack (left) and a user plane protocol stack (right).

 

Xn interface

The Xn interface is an interface between an access network and an access network, and is an internal interface. Control plane on the left, user plane on the right

• Xn-C is the interface between CU-C
• Xn-U is the interface between CU-U

E1 interface

The E1 interface is the interface between CU-C and CU-U. The E1 interface only has the control plane interface. It is only used for the exchange of signaling, not for the forwarding of user data.

F1 interface

The F1 interface is the interface between the CU and the DU. The left side is the control plane protocol stack (F1-C interface), and the right side is the user plane protocol stack (F1-U interface)

 control surface

• The main functions of the control plane RLC and MAC layer functions are consistent with those of the user plane
• PDCP layer completes encryption and integrity protection
• The RRC layer completes broadcasting, resource control, and mobility management
• The NAS layer completes core network bearer management, authentication and security control

user plane

Main functions of the user plane:

• header compression, encryption, scheduling
• A new protocol layer SDAP is added to the 5G user plane: complete the QoS mapping function from flow to radio bearer, and mark each packet with a flow identifier (QFI: QoS flow ID)

5G network deployment

Non-standalone networking (NSA)

• Only supports eMBB
• Need to upgrade LTE base station (4G base station) and core network to support NSA
• 5G NR (New Radio Network) needs to provide Customized 4G NAS UE with 5G RRC eLTE theory to support LTE terminals

Independent networking (SA)

• Support all 5G functions
• Does not affect LTE
• Use 5G UE LTE terminals under 5G NR to continue to use under LTE network

MR-DC technology

MR-DC technology means that a terminal can connect to 4G network and 5G network at the same time, and use the two networks for business at the same time. A terminal device requires at least two MAC entities.

• DC - dual connection

5G network spectrum division and application

• 5G business content includes: eMBB (enhanced mobile broadband <4G enhanced version>), URLLC (ultra-reliable low-latency communication) and mMTC (massive machine type communication)
• 5G features: high bandwidth, low latency, large capacity
• 5G spectrum characteristics: high frequency band, wide distribution, complex allocation

Basic Concepts of Frequency

Under certain conditions, the speed of radio waves is equal to the speed of light. Light waves rely on the transmission medium of radio waves.

When the speed of radio waves is constant, the wavelength is inversely proportional to the frequency, that is, the frequency increases and the wavelength becomes shorter; the frequency decreases and the wavelength increases.

5G network working frequency band and bandwidth configuration

The 5G spectrum is divided into two regions FR1 and FR2, and FR2 is called millimeter wave communication .

FR1 corresponds to duplex mode

• FDD - frequency division duplex (uplink and downlink frequencies are different)
• TDD - time division duplex (uplink and downlink frequencies are the same)
• SDL - downlink auxiliary frequency band (only downlink has frequency)
• SUL - uplink auxiliary frequency band (only uplink has frequency)

FR2 corresponds to duplex mode

• Only TDD

FR1 and FR2 channel bandwidth

Channel bandwidth: maximum transmission bandwidth configuration

 The maximum transmission bandwidth configuration of FR1 is related to the SCS, and its maximum transmission bandwidth configuration is as follows:

• SCS-sub-carrierspace, subcarrier spacing
• NRB - the number of RBs with the maximum transmission bandwidth
• Maximum support 100MHz

The maximum transmission bandwidth configuration of FR2 is as follows:

Maximum support 400MHz

Calculation formula for the minimum guard bandwidth:

(CHBW (bandwidth M) × 1000 (kHz) - number of RBs × SCS × 12)/2-SCS/2

• eg: FR1 100MHz (100*1000-273*30*12)/2-30/2＝845KHz

5G network working frequency band

GSM - Global System for Mobile Communications

5G Base Station Activation and Commissioning

• The goal of the commissioning and commissioning of the 5G system is to complete the establishment of the 5G logical cell. The prerequisite for the normal establishment of the logical cell is the normal establishment of the local cell.
• Requirements for the normal establishment of a local cell: transmission resources, baseband resources, radio frequency resources and clock resources are all "available"

Base

The commissioning and commissioning of the 5G system requires the coordination of access network, transmission network, and core network resources. 5G base station system usually consists of EMB6216+AAU

3.5G S111：

• Each AAU establishes a 100M NR cell
• Insert a HBPOF baseband board to support 3 100mm 64-channel NR cells

3.5G S111111：

• Each AAU establishes a 100M NR cell
• Insert two HBPOF baseband boards, each supporting three 100mm 64-channel NR cells

3.5G S222：

• Each AAU establishes two 100M NR cells
• Insert two HBPOF baseband boards, each supporting three 100mm 64-channel NR cells
• The two optical ports of AAU1 and AAU2 are respectively connected to the same HBPOF baseband board, and the two optical ports of AAU3 are respectively connected to two baseband boards

process

• Before the opening of the 5G base station, preparations for opening and commissioning are carried out, including: inspection preparations and software preparations.
• Use the LMT software to connect to the main control board of the BBU. Ensure that the main control board of the BBU is in the same network segment as the commissioning laptop (configure the IP address of the PC). Usually, the IP address of the PC is set to: 172.27.245.100, and the subnet mask is 255.255.255.0
• The LMT version must match the software version used by the base station
• Opening time of BBU and AAU
• When activating a dual-mode base station, you need to perform 5G activation commissioning first

physical layer process

overview

The main function:

• Error detection of the transport channel and provide indication to higher layers
• FEC encoding/decoding of transport channels
• HARQ soft combining
• Mapping of coded transport channels to physical channels
• Physical Channel Power Weighting
• Physical channel modulation and demodulation
• Frequency and Time Synchronization
• Measure radio characteristics and provide indications to upper layers
• MIMO Antenna Processing
• Physical RF Handling (RF Related Specifications)

subframe configuration

NR frame structure:

• The fixed frame structure of LTE is no longer used, and the combination of semi-static unlimited resource control (RRC) configuration and dynamic downlink control information (DCI) configuration is used for flexible configuration
• RRC configuration: cell-specific and UE-specific (semi-static mode)
• DCI configuration: SFI (slot format indication) and DCI scheduling (dynamic mode)
• Supports dual-cycle configuration

1. Option1: 2.5ms double cycle frame structure. Every 5ms contains 5 full downlink time slots, three full uplink time slots and two special time slots, DDDSUDDSUU

Physical Channels and Signals 

• PSS - primary synchronization signal, carrying cell ID NID(0,1,2)
• SSS - secondary synchronization signal, carrying cell ID group NID (168) and frame timing information

Physical layer channels can be divided into uplink channels and downlink channels

• downlink
  • Downlink channels include physical layer broadcast channel (PBCH), physical layer downlink control channel (PDCCH), physical layer downlink shared channel (PDSCH)
  • Downlink signals include demodulation reference signal (DM-RS), phase tracking reference signal (PT-RS), channel information reference signal (CSI-RS), primary synchronization signal (PSS) and secondary synchronization signal (SSS)
• Uplink
  • Uplink channels include physical layer random access channel (PRACH), physical layer uplink control channel (PUCCH), physical layer uplink shared channel (PUSCH)
  • Uplink signals include demodulation reference signal (DM-RS), phase tracking reference signal (PT-RS), sounding reference signal (SRS)