5G RAN basics and changes in RAN deployments

1. 5G RAN Fundamentals
Ravi Sharma

2. Table of Contents
• RAN fundamentals
• Traditional v/s New RAN architectures
• Disaggregation and plane separation
• C-RAN, V-RAN and O-RAN
• Examples/ Use cases

3. RAN Fundamentals
• The radio access network (RAN) is the basic component of cellular
technology
• It has evolved through the generations of mobile communications (1G
through 5G).
• Example of RAN technology is
• GRAN – GSM radio access network
• UTRAN – UMTS radio access network
• E-UTRAN
• 5G RAN

4. Basic Components of mobile network
Core
Transport
Radio access network
(RAN): uses radio
frequencies to provide
wireless connectivity to
the end user devises
UE User Equipment –
Generally a mobile
phone or wireless
CPE/dongle.
Transport networks- It
connects the RAN to
Core part of mobile
network. Also referred
as backhaul.
Mobile Core : It provides
the control and
connectivity within the
network and out side
the network
Radio Access Network
UE

5. Radio Access Network: Basic Components
Base band Radio Antenna
Digital Signal processing Digital information to
radio signal
Electrical Signal to
radio waves
Above is an example of traditional RAN set up
1. Baseband Unit
2. Radio Unit
3. Antenna

6. How the RAN Architecture evolved
2G 3G 4G 5G
BTS BSC
Nod
eB
RNC eNodeB Core
Core Core
RRU BBUCPRIRRU BBUCPRI
RNC
gNodeB Core
RU DU CU
AAU
CPRI/eCPRI F1
• Possible C RAN deployment
• BBU Pool
• Functional Split based RAN
deployment Options

7. How the RAN Architecture evolved
2G 3G 4G 5G
1. BTS is
combination of
Baseband & Radio
2. Centralized
control in form of
BSC
3. CPRI was not
introduced
1. NodeB is
combination of
Baseband & Radio
2. Centralized
control in form of
RNC
3. CPRI introduced,
RRU deployed on
tower and BBU in
shelter/ cabinate
1. eNodeB is
combination of
Baseband & Radio
2. Distributed control on
eNodeB itself
3. CPRI based
centralized BBU
deployed in few
countries
1. gNodeB is combination of
Baseband & Radio
2. Distributed control on
gNodeB itself
3. Functional Splits possible at
MAC, L3 and Phy layer etc.
providing multiple
deployment options
4. DU & CU based on eCPRI
interface and F1 interface
respectively
5. AAU – RU + Antenna – Active
antenna Unit is

8. 5G RAN – CRAN, O RAN , vRAN
CRAN
Centralized RAN has baseband
processing unit in centralized
location connected to multiple
radio equipment via fronthaul.
Conventional CRAN used CPRI as
fronthaul standard, which
requires very high bandwidth in
5G RAN scenario.
vRAN
5G RAN becomes software-
defined and programmable.
This provides RAN architecture
flexibility and platform
simplification.
In O-RAN based implementation,
CU, DU can be installed as
VNF/CNF on x86 based
commodity hardware.
Vendor specific implementation
of vRAN need specialized
hardware for DU. And vendor
specific front haul equipment.
O-RAN
The O-RAN specifications
defined open interfaces and new
nodes to support virtualized RAN
network, white-box hardware and
standardized interfaces
It standardized 7.2 functional split
and front haul based on eCPRI
framework.
It introduces RAN Intelligence
Controller (RIC) as a fundamental
element which provides AI-driven
policies and algorithms to manage
RAN decision making.

9. 5G functional Splits
Data link
layer
Physical
Layer
RF
Low Phy
High Phy
MAC
RLC
PDCP
Network
layer
RRC IP
Transport Blocks
MAC SDU
RLC SDU
Sub carriers
IQ Symbols
PDCP SDU
RU
DU
CU
eCPRI
Ethernet
 The Split 2 and Split 7 are mostly recommended by
open communities.
 Split 2 is mostly recommended for Small cell
forum for small cell
 Split 7 is recommended from O RAN community,
and a ecosystem of equipment provider are
evolving.
 The traditional 5G vendors are also supporting
 Massive MIMO support the

10. 5G New Concepts
MEC
RAN Slicing
Functional Splits
Programmability
– O RAN RIC
Multi-access Edge Computing (MEC) offers application developers and content providers
cloud-computing capabilities and an IT service environment at the edge of the network.
This environment is characterized by ultra-low latency and high bandwidth as well as
real-time access to radio network information that can be leveraged by applications.
5G RAN slicing secures the efficient allocation of radio resources to support SLA
fulfillment for a wide range of services and enabling new business
Programmability of 5G RAN slicing -Software-Defined RAN (SD-RAN) controller
dynamically reassigns resources to each slice. SD-RAN is developing a near-real-time RIC
(nRT-RIC) and a set of exemplar xApps for controlling the RAN.
The programmability is also because of virtualization of RAN infrastructure.
The functional split determines how many Base Station (BS) functions to leave locally,
close to the user, with the benefit of relaxing fronthaul network bitrate and delay
requirements, and how many functions to centralize with the possibility of achieving
greater processing benefits.

11. Example & use cases