World ’ s Largest 4G Network

1. World’s Largest 4G Network Feb, 2106 BS Subscriber ~360M 4GSubscribers ~1.1M 4GBSs ~90M@2014 ~720K@2014 Sales volume 210M+ Types1000+, Price <50$ Terminal Coverage ~100M@2014 ~1.2B pop (~86%), Reach Villages ~330Cities@2014

2. 5G Era: Rethink Fundamentals Green Communication Research Center established in Oct. 2011, initiated 5G Key Tech R&D. Green To start a green journey of wireless systems For no more “cells” To make network application/load aware Soft To make BS invisible To enable wireless signal to “dress for the occasion ” To enable Soft RAN via NGFI Super Fast To enable flexible configuration of diversified access points and optimal baseband function split between BBU pool & RRS “Towards Green & Soft: A 5G Perspective” IEEE Comm. Mag, Vol.52, Feb.2014

3. 5G New Requirements Immersive Seamless Ultra Dense Tactile Massive Ultra Reliable Seamless Coverage, Hot Spot High Capacity, Low-power Massive-connection, Low-latency Ultra-reliable New design principles, new key technologies, …

4. E2E 5G System Key Technologies Latency redu. V2X LTE evolution Low freq. eMBB NB-IOT Green and Soft SDN/NFV Core Network Transportation network PTN PON SDAI (enabled by MCD) RAN Seamless wide-area coverage Hotspot & high data rate Low-power & massive-connections Low-latency & high-reliability

5. User Centric RAN (UCN):C-RAN a key enabler CN-RAN Repartition AutonomousNetwork ServiceAwareness Network Slice as a Service Localized data, service & forwarding Turbo Charged Edge UnifiedAccess& SeamlessMobility RAN restructure Multi-Connectivity & FlexibleTopology Framework of radio access network

6. Fronthaul challenges surfaced with C-RAN (2011) C-RAN CMCC has conducted extensive trials to seek cost-effecitive FH solutions in LTE era • Centralized Control and/or Processing • Collaborative Radio • Real-Time Cloud • Clean System Target Distributed BTS Distributed BTS Traditional BTS Traditional BTS Fronthaul used to be an issue for LTE C-RAN: CPRI Compression and WDM

7. Traditional FH solutions must be revisited in 5G era

8. NGFI (xHaul) • 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. 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. Considering the C-RAN centralized deployment and the technologies of 5G, FH is facing a bandwidth explosion. • 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.

10. 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. Decoupling UL/DL Processing 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.

12. NGFI Progress • Lead of IEEE 1914 (NGFI) WG inIEEE • 1stNGFIWS held & NGFIWP 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/FHpromotion and study in ITU-T,IEEEand3GPP • NGFIPaper in IEEE Communication Magazine&GLOBECOM2015 • “RethinkFronthaul for Soft RAN”, IEEE Comm. Mag. 2015 • “NGFI,The xHaul”, GLOBECOM 2015 White Paper on NGFI released in June 2015 NGFI feasibility study with Xilinx

13. 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. IEEE NGFI (1914) WG • 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 7 Founding members • http://grouper.ieee.org/groups/1914/ • The first NGFI WG meeting, April 25-28, San Jose, CA Contact: huangjinri@chinamobile.com

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