Fronthaul Challenges & Opportunities

Transcription

1 Fronthaul Challenges & Opportunities Anna Pizzinat, Philippe Chanclou Orange Labs Networks LTE world summit 2014 Session : backhaul summit June 2014, Amsterdam RAI, Netherlands

2 Contents 1. Cloud RAN Cloud RAN drivers Local RAN Centralized RAN 2. Fronthaul Fiber fronthaul and wireless fronthaul 3. Conclusion Centralize if you can, distribute if you must 2

3 Cloud-RAN compared to Distributed-RAN Conventional Architecture Cloud RAN Architectures Standard BS Remoted Centralised Intra Pooling + CoMP Inter Pooling + CoMP Possible future products Traditional Site Remote Head Site (RRU) 3 cells (1 site) per Phase 1 CRAN 3 cells (1 site) per Upto 30 cells per Phase 2 CRAN Upto 30 cells per Upto 30 cells per 30 or more cells per Future CRAN 30 or more cells per 30 or more cells per Site Site Site 1 Site 2 BS Co-Ax Radio BS BS Intra-site Radio pooling Radio (typ. 3 cells/sectors max and several Mobile Central Office 1 X2 2 Technologies: 2G, 3G,4G) 3 to 12 fronthaul links BS Radio Central Office Internal Inter-site pooling: 30 -?hundreds? Switching Layer Internal fronthaul links Central Office Internal Internal between remote and Radio head known as Fronthaul CRAN = Cloud RAN = Base Band Unit BS = Base Station = Remote Radio Head

4 C-RAN: centralized Already deployed in some countries. Today one can already manage 6. Next generation of products will support multiple sites (first level of pooling) and an internal interface to enable CoMP support. CoMP=Coordinated MultiPoint AAA, Active Antenna Arrays Wireless Central Office System module IP/MPLS network Optical Fiber System module S1 Digital-RoF System module Fronthaul : CPRI C-RAN: intra & inter pooling + CoMP 4 4 Cs of C-RAN: Centralization, Cloud, Cooperation, Clean At research level: reach pooling at user equipment (UE) level

5 C-RAN drivers Interest coming from network operational teams : site engineering solution due to increased network rollout difficulties Antenna site simplification: footprint reduction, renting cost reduction, reduced time to install Antennas sites with negotiation problems Adding new radio access technologies on existing sites with very limited space Find new locations to replace sites that have to be switched off or solution for failed negotiation sites Reducing building cost (crane, metallic structure, etc.) and renting cost Reducing the electrical consumption, maintenance on site Less or not any cooling cabinets and shelters Decrease antenna site time to build and time to repair Contribute to RAN strategies about Tower sharing Solar powered antenna site Simplification of operational installation procedures at antenna sites 5 Drivers = cost reductions & ease of deployment

6 C-RAN drivers Radio performances, very low latency between s enables: Better performance in mobility Improved uplink coverage Higher capacity and improved cell edge performance with inter-site CoMP When s are centralized (e.g. with C-RAN), it means pooling and aggregation gains possible across a number of sites and energy efficient (see slide in annex) C-RAN is future proof for LTE-A and beyond In case of hetnets, higher interference is expected The same shared between small cells and parent macrocell could provide even higher gains than in a macrocell scenario. Central Office System module 6 s are in a secured location: no need for IPSec The new fronthaul segment is the key to assess the TCO (total cost of ownership)

7 How to build a fronthaul solution? 1. Technical requirements: CPRI: digitized radio signal high data rates 3 sectors LTE 20MHz 2x2 MIMO 3x2.457Gbit/s technical aspects Complete radio configuration LTE+ 3G+ 2G: up to 15 s Latency + synchronization + jitter also to be taken into account 2. Business aspects: low cost and scalability regulatory aspects * business aspects 3. Regulated countries: the fronthaul solution must be available for other operators wholesale offer Fronthaul must be monitored to provide SLA by dedicated fiber monitoring solution different levels of SLA are possible Antenna site demarcation point demarcation point Optical Fiber demarcation point Central Office outdoor compliant and as simple as possible 3. Non-Regulated countries: fronthaul provided by the RAN vendor demarcation point Wireless 7 Optical fiber is needed for the fronthaul Wireless fronthaul shall also be considered Mobile operator fiber / wireless provider Mobile operator

8 Local C-RAN Micro/small cell Macro cell Micro/small cell Cell site cabinet Wireless or Optical Fiber coax Wireless or Optical Fiber RRU RRU RRU CSG Central office backhaul 8

9 Wireless fronthaul: a reality today! Antenna WFM WFM FrontLink 58 Product Digital Interfaces Antenna Antenna RF Interface Wireless fronthaul on Orange commercial network with FrontLink solution from Three sectors LTE 2600 MIMO 2x2 3x2.457Gbit/s CPRI on a wireless fronthaul link In less than 70 MHz bandwidth 30 cm 9

10 Wireless fronthaul: similar KPIs as fiber Fiber-based Fronthaul Wireless Fronthaul Fiber-based Fronthaul Wireless Fronthaul Network accessibility Network retainability Fiber-based Fronthaul Wireless Fronthaul Network mobility 10 Apple to apple comparison between fiber and wireless fronthaul over 3-months period

11 Wireless fronthaul: similar KPIs as fiber RTT ping 32 bytes RTT ping 1400 bytes Network integrity 11 Apple to apple comparison between fiber and wireless fronthaul over 3-months period

12 Wireless fronthaul enables local C-RAN Macro site Remote macro sector Micro sector (3G and/or 4G) Wireless Fronthaul Remote macro sector Macro site «local C-RAN» Remote macro sector Remote Micro sector Remotre Micro sector Remote Micro sector 12 With wireless fronthaul, turn existing macro site into local C-RAN Easier and faster deployment, same network architecture, better radio performance

13 From local C-RAN to centralized RAN Mobile coverage done by only s Central office Fronthaul 13 s Stack

14 How to build a fronthaul solution? Focus on fiber fronthaul RRU: Remote Radio Unit : Remote Radio Head : BaseBand Unit CSG: Cell-Site Gateway D-RoF: Digital Radio over Fiber, CPRI or OBSAI Local RAN Wireless coax RRU RRU RRU Cell site cabinet CSG Mobile (Carrier Ethernet, PON, MW) fibre Central Office Centralised RAN Wireless D-RoF Demarcation point Mobile Fronthaul fibre Optical Distribution Network Demarcation point IP/MPLS network Dark fiber Carrier Network (Eth., OTN, PON) D-RoF Carrier fronthaul D-RoF 14 Not enough fiber available? Challenges: latency, jitter, synchronization Too expensive for OTN

15 How to build a fronthaul solution? Focus on fiber fronthaul Dark fiber PRO S CON S D-RoF Carrier Network (Eth., OTN, PON) Native fronthaul solution Need fibers, lot of fibers No native monitoring and OAM D-RoF High efficiency fiber sharing Native OAM and demarcation Risk on performance (latency, synchro) needed for CPRI CPRI rate dependent Power supply required Foot print (cooling cabinet) Cost issue 15 D-RoF Passive WDM low footprint Carrier fronthaul Shared fiber Active WDM: - provide infrastructure monitoring and OAM - clear demarcation point - CPRI transparent (no framing, bit rate independent) - multiplexing low and high CPRI rate and other traffics (alarm, GPS ) - CWDM with colorized transceivers (outdoor compatible) already available - scalability to DWDM with colorless and outdoor transceivers under investigation

16 Conclusions and next steps Centralize if you can, distribute if you must C-RAN drivers and global perspective - Radio Site engineering solution (footprint reduced, energy efficiency, less operations on site, etc.) - Radio performance improvements and future proof for LTE-A - Hybrid Fronthaul/ solution needed to address HetNets - C-RAN to co-exist with regular RAN architecture - in secured place and existing location Wireless Fronthaul - Wireless fronthaul commercially available today (up to 7.3Gpbs): enabling network densification and local C-RAN - Use of millimetric bands in future for massive small cells (mrru) deployment (Nx10Gbps fronthaul links in dense urban areas) Fiber Fronthaul 16 - CWDM ready: good, simple, cost effective option with additional passive fiber monitoring - DWDM tomorrow with colorless transceivers and high number of available wavelengths

17 Is it time to rethink CPRI? Energy efficiency Standardisation - No sleep mode? - Constant rate -CPRI is coming from industry forums and not from a standardization group (cf. ETSI Open Radio Innitiative) -CPRI is defined as a backplane extension and not a network interface CPRI redefinition - CPRI transport: include natively the OAM (Operations, Administration and Maintenance) of the medium: Fiber, wireless, etc - New function splitting interface to reduce bandwidth? - Packetized fronthaul? - Network architecture of Fronthaul (PtP, MPtoMP) - Reference configuration including demarcation point 17

18 merci

19 Energy consumption gain Calculation made on Rennes area France (one on 10 big cities) 15-km square coverage area, 86 cell sites, 13 intermediate central offices and one Core CO Total Energy Consumption [ kw ] PSVAC * OTN CSGW Optical transceiver Based on average consumption of commercial equipments *PSVAC: Power Supplying, Ventilation and Air Conditioning CSGW: Cell Site GateWay