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Transcript of ContentInstallation Aspect C-RAN Total N Site - N BBU - Nx3 RRU Distributed-RAN Total N Site - Nx3...

  • 1

    Content Introduction

    LET Market Status

    C-RAN overview

    C-RAN Benefits and Features

    Benefits: Installation/Evolution/Performance Aspects

    Features: Centralized Coordination, Inter-site Operation

    C-RAN Architecture

    DU-RU Function Split

    Fronthaul Technology

    Future Evolution

  • 2

    Soaring LTE Compare to 3G

    (Source : WCIS, Informa Jan 2014)

    Dec 2009 Dec 2012 Dec 2014 (E) Dec 2013 Dec 2010 Dec 2011 LTE

    Oct 2001 Oct 2002 Oct 2003 Oct 2004 Oct 2005 Oct 2006

    2007

    263 Commercial operators in 97

    countries

    41 million subs added in Q4 2013

  • 3

    LTE Expansion in Korea

    13

    Smart Cache™

    3G

    22

    VoLTE CA

    Multi Carrier

    LTE Launch

    Wideband LTE

    eMBMS C-RAN

    8

    6 Carrier 6 Sector

  • 4

    World Firsts in Korea

    4.9M Subscribers

    300Mbps

    Jan. 2014 Commercial

  • 5

    LTE Traffic Usage in Korea

    2.5 GB

    30.9 PB

    43.3 PB

    50 PB

    58.4 PB

    68.4 PB 72.7 PB

    79.8 PB

    86.9 PB

    1.8 GB

    2.8 GB

    Traffic usage per subscriber

    Total traffic usage

    ~50% Growth in LTE traffic per user in just over 1 year

  • 6

    Mobile TV in Korea

  • 7

    Mobile TV in Korea

    (Paid Subs.)

  • 8

    Mobile Traffic Explosion

    http://www.imdb.com/media/rm277137664/tt3268458?ref_=tt_ov_ihttp://www.google.co.kr/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=1iEuyhnjyNMo2M&tbnid=EJQ8NfpOmp9NcM:&ved=0CAUQjRw&url=http://www.comsoc.org/blog/internet-things-and-things&ei=FN6KU5PKDo_y8QXzl4CICw&bvm=bv.67720277,d.dGc&psig=AFQjCNHM-F2Jx5SMMD09gfOQMpmq_pnj-Q&ust=1401696016655087

  • 9

    Macro cells Small cells

    Mobile Traffic Explosion

  • 10

    Centralized Baseband Processing

    Cloud Computing

    Coordinated Radio

    Clean Radio Access Network

    4C in C-RAN

  • 11

    Network Evolution

    Traditional BS (DU/RU in one box)

    Distributed RAN (D-RAN)

    (DU/RU in different box )

    Centralized RAN (C-RAN)

    (DU Cloud + Remote RU)

    DU

    DU Cloud

    RU

    DU

    Server

    RU

    * DU: Digital Unit * RU: Radio Unit

    DU

    RU

  • 12

    C-RAN Network Diagram

    Distance < 20 km

    Active Optic MUX

    Passive Optic MUX

    Active WDM

    Passive WDM

    Fronthaul Network (Optical Transport

    Network)

    * WDM : Wavelength Division Multiplexing * RRU: Remote Radio Unit

    DU Centralized Site Remote Site

    (Baseband Processing, Coordinator, Edge App.)

  • 13

    C-RAN in Seoul (1/2)

    ※ Seoul covers 600Km2, 10M pops

    Central Site

  • 14

    C-RAN in Seoul (2/2)

    Optic MUX

    DU Centralized Site

    Remote Site

  • 16

    Installation Aspect

    C-RAN

    Total N Site - N BBU - Nx3 RRU

    Distributed-RAN

    Total N Site - Nx3 RRU 1 C-RAN BBU

    C-RAN BBU

    RRU RRU RRU

    BBU

    RRU RRU RRU

    BBU

    RRU RRU RRU

    BBU

    RRU RRU RRU

    RRU RRU RRU

    RRU RRU RRU

    Centralized-RAN

    * DU: Digital Unit * BBU: Base Band Unit * RRU: Remote Radio Unit

    Reduced CAPEX/OPEX, CO2

    Simpler site installation

    Reduced site rental and electricity cost

  • 17

    Evolution Aspect

    Site visiting - Change Tech-A BBU to Tech-B BBU

    Central office visiting - Change Tech-A Card to Tech-B Card

    Tech-B card

    Tech-B C-RAN Tech-A

    C-RAN

    Easier evolution with new h/w, new technology

    • e.g. BBU + IT server

  • 18

    Performance Aspect

    Wireless Channel Information

    Scheduling info. (QoS/CQI/Load)

    IP Network

    Radio Resource Coordination Enhanced Performance

    Information exchange over IP network - Long Latency, Low Speed

    Information exchange side the Rack - Short Latency, High Speed

    Distributed-RAN Centralized-RAN

    C-RAN

    * QoS: Quality of Service * CQI: Channel Quality Information

    Easier evolution for better performance with new h/w, new technology (e.g. BBU + IT server)

  • 19

    C-RAN Coordination (1/3)

    Optimal resource allocation over multi-cell network

    in a centralized manner

    Cell#3

    Cell#1

    Cell#2

    Cell#N

    Cell#4

    UE A

    UE B

    UE D

    Cell#1 Cell#2 Cell#3

    Cell#4 Cell#5 Cell#6

    Cell#7 Cell#8 Cell#9

    Cell#N-1 Cell#N

    UE B UE A

    UE C

    UE D

    Channel/Scheduling Info.

    (QoS/CQI/Load)

    Resource Coordination

    C-RAN Coordinator

  • 20

    C-RAN Coordination (2/3)

    Cells cooperate with each other in a distributive way. (Each cell decides its own air resource usage.)

    To increase the system efficiency in long-term average sense

    Limited information (specified in the standard interface) is shared among cells.

    Cells are coordinated in a centralized way. (Central coordinator decides the whole network air resource coordination.)

    To increase the system efficiency at every millisecond

    More information (than standard interface) is exchanged with central coordinator.

    ICIC C-RAN Coordination

    Interference

    X2 Load Information

    Interference

    Channel Info.

    Scheduling Info.

    C-RAN Coordinator

    Coordination Output

  • 21

    C-RAN Coordination (3/3)

    Serving

    Nbr 2

    VoLTE VoLTE VoLTE

    Serving Cell

    Nbr 1

    VoLTE UE

    VoLTE is affected by neighbor cell interference

    Nbr 1

    Nbr 2

    Serving

    Nbr 2

    VoLTE

    blank

    VoLTE

    blank

    VoLTE

    blank

    Serving Cell

    Nbr 1

    VoLTE UE

    Interference avoidance by blanking

    Nbr 1 blank blank blank

    Nbr 2

    Intf., Intf.

    Intf. Intf.

    VoLTE Example Voice quality improvement at cell edge

  • 22

    UL CoMP Joint Reception (JR)

    Uplink signal is jointly received at multiple points to improve the received signal quality

    Conventional UL CoMP JR

    UL signal path used by serving cell

    *UL CoMP: UpLink Coordinated Multi-Point

    SINR

  • 23

    Inter-site Carrier Aggregation (1/2)

    Carrier aggregation using cells from different sites

    Chooses Pcell and Scell with the best signal quality

    Seamless CA in coverage mismatch area

    * Pcell: Primary cell * Scell: Secondary cell

    without CA

    Thro

    ugh

    pu

    t

    이동구간 Coverage mismatch area

    with CA

  • 24

    Inter-site Carrier Aggregation (2/2)

    Select and aggregate the best cell of each carrier

    22.3 Mbps 45.9 Mbps

    1.8 GHz

    800 MHz

    Cell 0 Cell 1 1.8 GHz 800 MHz

    Cell 0 Cell 1

    Conventional CA Inter-site CA

    (Best Cell Aggregation)

    1.8 GHz cell coverage

    800 MHz cell coverage

    1.8 GHz cell coverage

    800 MHz cell coverage

    PCell 8.3dB(15.6M) 1.6dB(7.5M)

    SCell -1.4dB(6.7M) 12.8dB(30.3M)

    8.3dB(15.6M) 1.6dB(7.5M)

    -1.4dB(6.7M) 12.8dB(30.3M)

    *Based on actual measurement in Korea (FDD, 10 MHz + 10 MHz)

  • 25

    HetNet Carrier Aggregation

    CA between Macro and Small cells

    Control and voice are supported by Macro cell

    No handover

  • 26

    One cell operation

    Same PCID for multiple N cells

    No handover among N cells with same PCID

    C-RAN supports larger and flexible N

    C

    A B

    A B C

    SIN

    R

    One Cell operation

    Conventional

    Small cell

    Small cell

    One Cell Operation

  • 28

    C-RAN Benefits and Pitfalls

    CAPEX/OPEX Savings

    Multiple sites share a high-density DU

    Small form factor for each site

    Fewer visits to sites for maintenance

    EPC

    Traditional RAN C-RAN

    EPC Backhaul Network

    Fronthaul Network Backhaul

    Network

    Transport Cost between DU/RU

    Current technology requires dark fibers

    because of high bandwidth

    Additional central offices required

  • 29

    Consideration for C-RAN (1/2)

    To minimize transport cost between DU and RU

    Minimization of the bandwidth

    Alternative transport solutions (e.g. Microwave, Ethernet)

    To maximize resource pooling

    High density DU, and DU pooling

    Reuse for evolved radio technology

    To maximize radio performance

    Edge performance enhancement by inter-site operation

    High-bandwidth and low-latency connectivity between DUs

  • 30

    Consideration for C-RAN (2/2)

    To maximize Maintenance Efficiency

    Plug and Play RU

    Automatic re-parenting between DU and RU

    To utilize the benefits of DU centralization

    Interworking with Coordination server, Cache server, Local breakout

    server, Analytics server, etc.

  • 31

    Since March 2013,

    Study of C-RAN Technologies

    • Function Split between DU and RU

    • DU pooling

    • Virtualization

    • RAN Sharing

    • Prototype Development * DU: Digital Unit * RU: Radio Unit * RAN: Radio Access Network

    NGMN Project C-RAN

  • 32

    DU-RU Function Split

    (Source: NGMN RAN Evolution C-RAN white paper )

    * IV : CPRI interface * IV’ : Compressed CPRI interface

    Function Split Options Delay

    Sensitivity Bandwidth

    Level Comment

    Partial L1 at site, L1/L2/L3 centralized

    High High • CRAN features applicable

    L1 at site, L2/L3 centralized

    High Medium • CRAN features not applicable

    L1/L2 at site, L3 centralized

    Medium Low • CRAN features not applicable • Less centralization effect

  • 33

    DU-RU Architecture

    Option C Option A

    DU

    RF

    RU PHY

    Layer 3 Layer 3 PDCP

    Layer 3 Layer 3 RLC

    Layer 3 Layer 3 MAC

    Layer 3 Layer 3 PDCP

    DU

    RF RU

    Layer 3 Layer 3 RLC

    Layer 3 Layer 3 MAC

    Layer 3 Layer 3 PHY

    DU

    PHY (Cell Processing)

    Front- end

    RF RU

    Layer 3 Layer 3 PDCP

    Layer 3 Layer 3 RLC

    Layer 3 Layer 3 MAC

    Layer 3 Layer 3 PHY

    (User Processing)

    Option B

    DU processing by IT server (Workload is proportional to user traffic amount)

    Much smaller bandwidth b/w DU and RU. Limited C-RAN features support.

    Conventional

    (Source: NGMN RAN Evolution C-RAN white paper )

  • 35

    Fronthaul Network Topology

    CO

    T

    RT

    RT

    RT

    RT

    RT

    RT

    RT

    RT

    CO

    T

    Point-to-Point Topology (A operator who owns abundant dark fibers)

    Ring Topology (B operator who wants to reduce dark fiber rental)

    * COT : Central Office Terminal * RT : Remote Terminal

  • 36

    DU-RU Interface: CPRI

    CPRI protocol layers

    * CPRI : Common Public Radio Interface

    LTE 20MHz 4x4 MIMO requires 5Gbps

  • 37

    Concept of CPRI Compression (1/2)

    …0010101111010101 Compression Decompression

    Reduced-rate IQ data (DL)

    Compression Decompression 0010101111010101…

    Reduced-rate IQ data (UL)

    Compression/Decompression algorithm is applied to both ends

    Baseband Processing Remote Radio Unit

    Optic Cable I/Q Sample I/Q Sample

    Compression for DL Decompression for UL

    Compression for UL Decompression for DL

  • 38

    Concept of CPRI Compression (2/2)

    * D. Samardzija et al., “Compressed Transport of Baseband Signals in Radio Access Networks”, IEEE Trans. Wireless Comm., Sep. 2012

  • 39

    Effect of CPRI Compression

    Before After

    Reduced Bandwidth between DU and RU

    Number of optic link and optic module is reduced

    10G x 2 10G x 1

    * COT : Central Office Terminal * RT : Remote Terminal

    2.5G x 8

    RT

    2.5G x 4 2.5G x 4 2.5G x 8

    RT RT

    COT RT

    RT RT

    COT

    Example: compression ratio of 2:1

  • 40

    CPRI over Ethernet

    Ethernet Fronthaul

    Ethernet based DU-RU Networking

    Automatic re-parenting between DU and RU

    Dynamic DU pooling

  • 41

    Analog Signal over Microwave

    CPRI to Analog over Microwave

    Limited distance

    Graceful performance degradation

    core

    network EPC M/W

    UDC CPRI

    RU

    central unit (cluster)

    PDCP

    RLC MAC PHY CPRI RF

    M/W

    UDC

    BWOptimized 150MHz

    BCPRI 4915.2Mbps

    (20MHz, 4x4 MIMO)

  • 43

    5G and C-RAN

    5G not standardized yet

    mmWave(eg. 28GHz) and very broad bandwidth(800MHz~1GHze)

    Lots of antennas (e.g. 64)

    UE peak throughput of 1Gbps ~ 1.5Gbps

    Providing services in hot spots due to short coverage

    C-RAN for 5G

    CPRI fronthaul may not be feasible due to very high sampling rate.

    Function split needs to be further investigated.

    Higher bandwidth between DUs is required.

  • 44

    Cloud based Services

    Fronthaul Network

    More intelligent processing by Cloud Server

    Radio performance enhancement by scheduler and SON processing

    Cache / Local Breakout / Analytics / M2M / Etc.

    Intelligent Processing

    * SON : Self Organizing Network * M2M : Machine to Machine