Cloud RAN fronthaul
- 1. www.mtigroup.com/mobilePublic Cloud RAN fronthaul Options, benefits and challenges. Aleksandra Checko, Industrial PhD student Aleksandra.Checko@mtigroup.com iJOIN Winter School "5G Cloud Technologies: Benefits and Challenges„ Bremen, 2015-02-23 www.fp7-harp.eu
- 2. www.mtigroup.com/mobile2 Public Outline of today’s presentation Base station architecture evolution towards C-RAN – Traditional base station (past) – With RRH (present) – Cloud RAN (C-RAN) (present/future) Fronthaul network – Bitrate, delay and sync requirements – Transport medium – Transport solutions Fronthaul evolution How? Why?
- 3. www.mtigroup.com/mobile3 Public Traditional base station Base station evolution Telecom Italia Demo Base station with RRH
- 4. www.mtigroup.com/mobile4 Public Through base station with Remote Radio Head Currently deployed Power efficient Easy cooling For different standards Interface: – Open Base Station Architecture Initiative (OBSAI) – Common Public Radio Interface (CPRI) (some parts are vendor- specific) – Open Radio Equipment Interface (ETSI-ORI) Fiber up to 20-40 km, usually p2p Baseband Unit (BBU) a.k.a. Data Unit BaseBand Traditional Macro BS Antenna BS cell Transport Control Synch RF PA BS with RRH Antenna cell RRHRF BBU BaseBand Transport Control Synch
- 5. www.mtigroup.com/mobile5 Public To C-RAN architecture Proposed by IBM in 2010 Cloud, Centralized processing, Cooperative radio, Clean RF RF C-RAN with RRHs Virtual BBU Pool RRH RRH RRH RF BaseBand Synch Control Transport BaseBand Synch Control Transport BaseBand Synch Control Transport BaseBand Transport Control Synch Fiber – Digital BaseBand Coax cable – RF
- 6. www.mtigroup.com/mobile6 Public Cloud RAN Remote sites - RRH FRONTHAUL Source: http://www.mti-mobile.com/ Source: http://krnet.or.kr/ Data center – BBU Pool
- 7. www.mtigroup.com/mobile7 Public Fronthaul transport network - “link” between RRH and BBU P2P link for base station with RRH Fronthaul network based on – WDM – Ethernet – OTN
- 8. www.mtigroup.com/mobile8 Public Requirements on bitrate & timing 20 MHz LTE, 2x2 antennas (MIMO) – 150 Mbps for users, 2.5 Gbps on fronthaul link (CPRI) Delay < 3 ms RRH-BBU-RRH (HARQ) ≈ 0.1- 0.2 ms on fronthaul (CMCC) Jitter < 65 ns (MIMO, 36.104) Frequency error < 50 ppb (Macro BS, 36.104) BER < 10e-12 (CPRI, for specific application)
- 9. www.mtigroup.com/mobile9 Public Which medium to choose? Medium Bit rate Distance Remarks Fiber 100Gbps + Tens km Copper 10 Gbps 100 m Microwave 1 Gbps (80GHz) 1.5 km LoS required 0 1 2 3 4 5 6 7 8 9 10 2011 2012 2013 2014 2015 2016 Million Mobile Backhaul Connections by Medium Air Fiber Copper Source: Infonetics Research, March 2012 Why to consider microwave, not fiber everywhere?
- 10. www.mtigroup.com/mobile10 Public (Yes, people are working on compression) Majority of algorithms – Remove redundancies in spectral domain, – Perform block scaling, – Use non-uniform quantizer – Up to 33% (3:1) compression ratio for 8% EVM – ALU, IDT University of Texas at Austin – rescaling, – non-uniform quantization, – noise-shaping error feedback – Resampling – 5:1 ratio One algorithm detects user activity – up to 7%! (14:1) – Telefonica I+D
- 11. www.mtigroup.com/mobile11 Public Transport solution Technology is ready (capacity not necessarily) CPRI / OBSAI CPRI / OBSAI WDM CPRI / OBSAI CPRI / OBSAI Microvawe Compression Compression Eth/CPRI/ OBSAI Eth/CPRI/ OBSAI Ethernet CPRI/ OBSAI CPRI/ OBSAI OTN BBU Pool RRH CPRI / OBSAI Point to point WDM-PON
- 12. www.mtigroup.com/mobile12 Public Ethernet enables to maximize multiplexing gains Among others to reduce cost of BBU pool A. Checko, et al. ” Cloud RAN for Mobile Networks - a Technology Overview”, IEEE Communications Surveys & Tutorials 0,0 0,5 1,0 1,5 2,0 0 10 20 30 40 50 60 70 80 90 100 Multiplexinggain Office cells (%) A. Checko, H. Holm, H. Christiansen, ” Optimizing small cell deployment by the use of C-RANs”, European Wireless 2014
- 13. www.mtigroup.com/mobile13 Public Timing in fronthaul Timing is really important Frequency of transmission Handover, coding 00 01 02 00 01 02 Device A Device B Solution: timing distribution GPS PHY layer clock – SyncEth Packet-based timing IEEE 1588v2 (PTP) Multiple Requirements Phase error LTE-A with eICIC/CoMP: ± 1.5 - 5 μs, MIMO: 65 ns Frequency error LTE – A TDD/FDD: ±50 ppb
- 14. www.mtigroup.com/mobile14 Public Shared Ethernet is even better for cost-saving Access network - fronthaul Aggregation network - backhaul BBU Pool CPRI / OBSAI Remote Radio Heads CPRI / OBSAI Aggregation network - fronthaul Aggregation network - backhaulRemote Radio Heads IQ over Eth CPRI2Eth Gateways BBU Pool GPS, 1588, ect RRH CPRI GPS?, 1588?, new solution? Variable delay RRH++ BBU Pool++ Traditional fronthaul Packet-based fronthaul Sync delivered together with data (CPRI) New Sync solution needed BBU Switching Multiplexing Widely deployed (reuse!) ! Fronthaul cost savings vs problems with delays ! Synchronous CPRI vs asynchronous Ethernet
- 15. www.mtigroup.com/mobile15 Public HARP optimization Looking when to use C-RAN Combining fiber and microwave Optimizing cell-BBU assignment
- 16. www.mtigroup.com/mobile16 Public Deploying C-RANs Trade off – Fiber length – Cells in the C-RAN – Multiplexing gain TCO vs. capacity A. Checko, H. Holm, H. Christiansen, ” Optimizing small cell deployment by the use of C-RANs”, European Wireless 2014
- 17. www.mtigroup.com/mobile17 Public Optimization model To maximize multiplexing gain and minimize fiber cost In multi C-RANs scenario Aggregated Traffic (h) Aggregated Traffic (h) 24 h 24 h
- 18. www.mtigroup.com/mobile18 Public Partial C-RANs Partial C-RAN – Some sites are excluded from the C-RAN and are backhauled to the nearest C-RAN site by MWR R. Al-obaidi; et. Al. ”C-RAN deployment scenarios”, DTU, 2014 Backhaul network Base Stations LTE MWR Fronthaul network Backhaul network BBU Pool CPRI Remote Radio Heads MWR Fiber Aggregated Traffic (h) 24 h S1
- 19. www.mtigroup.com/mobile19 Public Updates from industry No more CPRI?! 4G towards 5G
- 20. www.mtigroup.com/mobile20 Public It is time to rethink fronthaul towards 5G New functional split between BBU and RRH – To reduce fronthaul data rate – Decoupling user-processing and cell-processing No more CPRI? Need for interface supporting: – Variable bit rate (traffic dependent to enjoy multiplexing gain) • To increase scalability – Packet-based • Synchronization is a challenge – Multipoint to multipoint – Fully standardized BBU Pool-- RRH BBU Pool Current C-RAN Future C-RAN 10 Gbps 10 Gbps 2 Gbps 2 Gbps 2 Gbps RRH++ BBU Pool-- 2 Gbps 3 Gbps 3 Gbps Vendor A Vendor A Vendor A Vendor B Vendor C
- 21. www.mtigroup.com/mobile21 Public Timely topic IEEE 1904.3 - encapsulation and mapping of IQ data over Ethernet IEEE 802.1 – CPRI fronthaul discussion with Time Sensitive Networking task force CPRI CPRI2? 3GPP - proposal on a study item on variable rate multi-point to multi- point packet-based fronthaul interface supporting load balancing
- 23. www.mtigroup.com/mobile23 Public Costs – 2x2 MIMO, 20 MHz LTE, 15+1 CPRI 2.5 Gbps – 3 sectors? 7.5 Gbps – Tens of BS over long distance? 100s Gbps Costs vs savings Fever BBUs?Fronthaul cost? Savings – Equipment – Energy Re-define fronthaul
- 24. www.mtigroup.com/mobile24 Public Base station architecture evolution BaseBand RF a) Traditional Macro BS Antenna RF RF c) C-RAN with RRHs Virtual BBU Pool BaseBand BaseBand RRH RRH RRH RF Fiber – Digital BaseBand Coax cable – RF BS cell BaseBand RF b) BS with RRH Antenna cell RRH BBU RF RF d?) Possibly C-RAN with new function split between BBU and RRH Virtual BBU Pool BaseBandBaseBand -- RRH RRH RRH RF BB BB BB FH network
- 25. www.mtigroup.com/mobile25 Public Deployment scenarios A. Checko, et al. „Cloud RAN for Mobile Networks - a Technology Overview”, IEEE Communications Surveys & Tutorials
- 26. www.mtigroup.com/mobile26 Public Take away points Fronthaul network capacity is a deal breaker for introducing C-RAN Fronthaul solutions so far rely on legacy deployments Industry is working on “redefining” fronthaul – towards switchable, multipoint-to-multipoint connections, with a strong focus on Ethernet- based solutions Thank you for your attention www.fp7-harp.eu