This document discusses 5G network architecture. It covers mobile towers, distributed and centralized radio access networks (D-RAN, C-RAN), virtualized RAN (V-RAN), fronthaul interfaces like CPRI and eCPRI, time-sensitive networking standards, mobile backhaul, and multi-access edge computing (MEC). Function splitting and different functional split options between baseband and radio units are described. Standards like IEEE 1914.1 for packet-based fronthaul are also summarized.

1. 5G Network Architecture
Lecturer: Rebwar Karimi
Nov 2019

2. Agenda
• Mobile Towers
• Remote Access Networks (D-RAN,C-RAN-V-RAN)
• Fronthaul Interfaces
• TSN
• Mobile Backhaul
• MEC
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3. Mobile Towers

4. D-RAN
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5. Why We Need C-RAN?
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6. C-RAN
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7. V-RAN
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8. V-RAN
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9. Fronthul Interface (BBU <-> RRH)
• CPRI
• OBSAI
• ORI
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10. CPRI
• it has introduced in 2003.
• The Parties cooperating to define the CPRI Specification and are now encompassing
Ericsson, Huawei, NEC and Nokia.
• Its latest version is CPRI version 7.0 and has released in 2015.
• It specifies a digitized serial interface between a base station referred to as REC in CPRI
terminology and an RRH or RE.
• REC (on BBU side) and RE (on RRH side) exchange:
• User Data
• CPRI Control & Management data
• CPRI frame synchronization information
• The specification supports both electrical and optical interfaces as well as point-to-
point, star, ring, daisy-chain topologies.
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11. CPRI
• An antenna-carrier (AxC): IQ data of either Rx or Tx of
one carrier at one antenna element.
• CPRI transports I/Q data of particular antenna and
particular carrier. This "unit" is called an AxC unit or
Antenna-Carrier unit.
• Example:
In LTE system, if I=16 bits and Q=16 bits
then one AxC is of length 32 bits.

12. CPRI

13. CPRI (Max Distance Can Support)
• This distance is constrained by the timing requirement of Hybrid Automatic Retransmit reQuest (HARQ) protocol used as a
retransmission mechanism between UE and eNB in an LTE network.

14. Time-Sensitive Networking (TSN)
• IEEE in cooperation with CPRI forum has defining a new fronthaul transport standard
(under IEEE 802.1cm project)
• The requirements can be divided into three categories:
• Class 1: I/Q and Control and Management (C&M) data (The round-trip delay for I/Q
is limited to 200 µs and maximum frame error rate is 10-7)
• Synchronization
• Class 2: eCPRI which has been recently added
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15. Synchronization Requirements in TSN
• Class A1: Strictest class with time error budget of 12.5 ns (one way) for applications
such as MIMO and transmit diversity.
• Class A: Time error budget up to 45 ns for applications including contiguous intracell CA.
• Class B: Budgets up to 110 ns for non-contiguous intra-cell CA.
• Class C: The least strict class delivers a budget up to 1.5 µs from the primary reference
time clock40 to the end application clock recovery output.
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16. CPRI Problem in 5G
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17. Solutions
• Function Splitting Options in eCPRI
• IEEE 1914.1 (NGFI)?
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18. eCPRI
• It uses the ethernet based messaging instead of TDM like in CPRI
• It doesn’t mandate any physical layer.
• Ethernet PHY and OTN can be valid options
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19. Function Splitting
• various functional splits offer options for different use cases
• option 1: CPRI, extremely bandwidth and latency demanding.
• high order options: much lower bandwidth and latency requirements (like option 2)
• Lower order options: provide joint coordination/scheduling for advanced mobility
application (for example option 7 or 8)
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20. Function Splitting

21. Radio Layer Functions
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22. IEEE 1914.1 Packet-Based Fronthaul Transport Network
• Architecture for the transport of mobile fronthaul traffic
• Analyzes different functional splits
• Purpose:
• enable critical 5G use cases such as mMIMO,CoMP,C-RAN
• simplifies network design, lowers costs by leveraging mature Ethernet-based
solution
• Fronthaul architecture: unified management & control common networking
protocol and network elements
• improves bandwidth efficiency, network scalability, sync performance and supports
cooperative radio modes.
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23. Single and Double Split Network Models
• NGFI I: interfacing low layers of base station processing chain
• NGFI II: interfacing mid/high layers of base station processing chain
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24. Backhaul
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25. Backhaul

26. MEC
• MEC or multi-access edge computing is an emerging 5G technology.
• it enables provisioning of cloud-based network resources and services near the
users.(like processing, storage, network)
• MEC servers can be located at different locations within the radio access network
depending on technical and business requirements.
• The main functions in the MEC platform include routing, network capability exposure,
and management
• because of processing the corresponding tasks in the proximity of the users so:
• reduce network congestion
• improve application performance

27. MEC Architectural Aspects
• high-level functional entities in the MEC framework:
• host-level
• MEC host
• MEC platform
• applications
• virtualization infrastructure
• the corresponding MEC host-level management entity
• network-level
• 3GPP radio access networks
• the local networks
• the external networks
• system-level
• MEC hosts
• MEC management necessary to run MEC applications within an operator network
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28. MEC Architectural Aspects
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29. MEC General Framework
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30. References
• https://www.netmanias.com/en/?m=view&id=blog&no=10670
• https://www.netmanias.com/en/?m=view&id=blog&no=6314
• https://www.netmanias.com/en/?m=view&id=oneshot&no=6259
• https://www.netmanias.com/en/?m=view&id=blog&no=6276
• https://www.netmanias.com/en/?m=view&id=blog&no=6220
• https://www.rfwireless-world.com/Terminology/CPRI-Line-Rates-and-Transport-Capacity.html
• https://www.ericsson.com/en/mobility-report/reports/june-2019/mobile-data-traffic-outlook
• https://www.statista.com/statistics/271405/global-mobile-data-traffic-forecast/
• https://www.youtube.com/watch?v=EBXZHIAmmms&t=409s
• https://www.youtube.com/watch?v=ne06ssVc3X0
• https://www.youtube.com/watch?v=UPucJcDAfSk&t=4s
• https://www.netmanias.com/en/?m=view&id=blog&no=10388&xtag=5g-c-ran-fronthaul-kt-korea-sdn-nfv-sk-
telecom&xref=mobile-network-architecture-for-5g-era-new-c-ran-architecture-and-distributed-5g-core
• https://www.youtube.com/watch?v=oaPRRbiaMyc
• https://www.netmanias.com/en/?m=view&id=blog&no=10388&xtag=5g-c-ran-fronthaul-kt-korea-sdn-nfv-sk-
telecom&xref=mobile-network-architecture-for-5g-era-new-c-ran-architecture-and-distributed-5g-cores
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31. Thank You
?