2. Green Communication Research
Center established in Oct. 2011,
initiated 5G Key Tech R&D.
Rethink Shannon
Rethink Ring & Young
Rethink Signaling & Control
Rethink Antenna
Rethink Spectrum & Air Interface
Rethink Fronthaul
Rethink Protocol Stack
To start a green journey of wireless systems
For no more “cells”
To make network application/load aware
To make BS invisible
To enable wireless signal to “dress for the occasion ”
To enable Soft RAN via NGFI
To enable flexible configuration of diversified access points
and optimal baseband function split between BBU pool & RRS
Green
Soft
Super Fast
“Towards Green & Soft: A 5G Perspective” IEEE Comm. Mag, Vol.52, Feb.2014
5G Era: Rethink Fundamentals
3. Pg 4 |
5G New Requirements
Immersive
Seamless
Tactile
Ultra Reliable
Massive
Ultra Dense
New design principles, new key technologies, …
Seamless Coverage, Hot Spot High Capacity, Low-power Massive-connection, Low-latency Ultra-reliable
4. UCN (enabled by C-RAN/NGFI)
High Freq.
RIT
Low Freq.
New RIT
Massive-MTC
RIT
Mission-Critical
RIT
Low-latency &
high-reliability
Seamless wide-area
coverage
Hotspot &
high data rate
Low-power &
massive-connections
Green and Soft
SDAI (enabled by MCD)
LTE evolution Low freq. eMBB NB-IOT
Latency redu.
V2X
PTN PON
Transportation
network
Core Network SDN/NFV
RAN
E2E 5G System Key Technologies
5. Pg 6 |
User Centric RAN (UCN): C-RAN a key enabler
Framework of radio access network
Localized data,
service & forwarding
Multi-Connectivity & Flexible
Topology
Autonomous
Network
Unified Access & Seamless
Mobility
Service Awareness
5G WiFi
4G
Signaling
Centralized
Radio Network Controller
广覆盖通用信令层
Macro signalling (data)
layer
本地数据接入点
Local Data Access
Data
D2D
Internet/App
Radio Data Center
RAN Entity
HSS/AAA/PCC
CN Entity
Smart Operation
Including C-RAN (Centralized and Cloud)
Next Generation Fronthaul Interface
(NGFI)
uMTC
mMTC
Mobile
Internet
CN-RAN Repartition
Turbo Charged Edge
RAN restructure
Network Slice
as a Service
6. Pg 7 |
Fronthaul challenges surfaced with C-RAN (2011)
Traditional BTS
Distributed BTS
C-RAN
• Centralized Control and/or Processing
• Collaborative Radio
• Real-Time Cloud
• Clean System Target
Fronthaul used to be an issue for LTE C-RAN:
CPRI Compression and WDM
CMCC has conducted extensive trials to seek cost-
effecitive FH solutions in LTE era
Traditional BTS
Distributed BTS
8. Pg 9 |
NGFI (xHaul)
Traffic dependent
Support of statistical multiplexing
Support of cell coordination
Antenna independent
Radio interface technological neutrality
• The key to achieve FH interface redesign lies in the function re-split
b/w BBU and RRU
• The new NGFI will further lead to re-design of underlined transport
networks with packet switching capability
9. Pg 10 |
Decoupling Ant./Non-ant. Related Processing
The evaluation of the existing FH Interface
(CPRI, OBSAI):
The FH bandwidth is proportional to the
number of antennas.
The FH bandwidth is at least 2 orders
of magnitude higher than BH bandwidth.
0.2 1.6 20
30
400
10000
0.013 0.384 150
0
2000
4000
6000
8000
10000
12000
GSM TD-SCDMA 8-antenna TD-LTE
Radio BW
FH BW
BH BW
Decoupling antenna/non-antenna related processing:
It is proposed that antenna related functions should be
moved from the BBU to the RRH.
FH bandwidth will decrease significantly if the BBU/RRH
function split can decouple the non-antenna related
processing and the antenna related processing.
Considering the C-RAN centralized deployment and the
technologies of 5G, FH is facing a bandwidth explosion.
The number of Carriers
in C-RAN
The number of
antennas
FH BW based on the existing
FH Interface
100 8 1Tbps
100 128 16Tbps
10. Pg 11 |
Decoupling cell/UE Processing
The existing FH interface is a constant bit rate interface, which is load
independent and does not match with the features of mobile traffic.
Decoupling cell/UE processing:
Cell processing is irrelevant to traffic load and is fixed no matter how many UEs are active.
FH bandwidth will be lower and load dependent.
In C-RAN Mode, cell/UE processing decoupling can further help reduce power consumption.
When the traffic load is low, part of C-RAN cloud resource can be shut down.
When there is no active UE, BBU software can be switched to a dormant state
11. Pg 12 |
S1 Termination
PDCP
RLC
Low MAC
Bit-level
Processing
Bit-level
Processing
Modulation
Layer Mapping
& Precoding
IDFT &
De-Modulation
Channel Estimation
& Equalization
Resource
Mapping & IFFT
FFT &
Resource De-Mapping
2
3
4
To RRU From RRU
5
High MAC
1"
1"
Some symmetrical BBU-RRU function
re-split solutions
（Taking LTE as an example）
There are many different aspects between UL
and DL:
Generally, the DL rate is not equal to the UL rate.
The bandwidth of UL and DL are not always in the
same order of magnitude.
The bit width of UL is usually larger than that of the
DL.
Decoupling UL/DL processing
NGFI design should take into account the
asymmetrical function split solutions.
For example, the function split solution 3 could
be used for UL while the solution 4 used for DL.
Decoupling UL/DL Processing
12. Pg 13 |
NGFI Progress
下一代前传网络接口
白 皮 书
White Paper of
Next Generation Fronthaul Interface
Version 1.0
June 4th, 2015
China Mobile Research Institute
Alcatel-Lucent
Nokia Networks
ZTE Corporation
Broadcom Corporation
Intel China Research Center
White Paper on NGFI released in June 2015
• Lead of IEEE 1914 (NGFI) WG in IEEE
• 1st NGFI WS held & NGFI WP released in June, 2015
- MoU signing with Broadcom, Intel, Alcatel-Lucent, HuaWei, ZTE,
Nokia, Xilinx & Altera
• Co-founder of IEEE 1904.3
• Leading the project of NGFI in CCSA
• NGFI as the key component in NGMN 5G WP, FuTURE 5G WP
• NGFI/FH promotion and study in ITU-T, IEEE and 3GPP
• NGFI Paper in IEEE Communication Magazine & GLOBECOM 2015
NGFI feasibility study with Xilinx
“Rethink Fronthaul for Soft RAN”, IEEE Comm. Mag. 2015
“NGFI, The xHaul”, GLOBECOM 2015
13. Pg 14 |
Challenges Ahead
Mapping of FH to Ethernet packet, undergoing in IEEE 1904 WG
Stage 1: CPRI encapsulation (applicable to 2G, 3G and 4G)
Stage 2: NGFI encapsulation for 5G
Latency
To meet RT requirement of wireless communication
Limited latency budget for FH (e.g. 250us defined in NGMN for LTE C-RAN)
Synchronization
LTE Frequency sync. of 0.05ppm & phase accuracy of +/-1.5us
Higher in 5G
Transport of FH packets
Over IP, MPLS, etc.
E2E QoS
O&M, protection etc.
14. Pg 15 |
IEEE NGFI (1914) WG
7 Founding members
• Target: efficient & scalable FH for
5G
• Officially approved: Feb. 2016
• Sponsor: IEEE COM/SDB
• 7 founding companies with more
than 50 subscribers so far from
~30 companies
• Scope of 1914.1 project:
- NGFI transport network
architecture
- Requirements
- Function split analysis for LTE
• http://grouper.ieee.org/groups/1914/
• The first NGFI WG meeting, April 25-28,
San Jose, CA
Contact: huangjinri@chinamobile.com
15. Pg 16 |
Thank you
For more information, please contact
icl@chinamobile.com
