The path toward C-RAN and V-RAN: benefits and challenges from operator perspective

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1 TELECOM ITALIA GROUP 5G World Summit London, June 2016 : benefits and challenges from operator perspective Marco Caretti Telecom Italia Engineering & TiLAB

2 Agenda The drivers for the RAN evolution RAN architecture evolution towards CRAN / VRAN Drivers for CRAN/VRAN deployment Fronthauling transport challenges and evolution MEC and CRAN/VRAN RAN Architecture towards virtualization and 5G

3 The drivers for the RAN evolution 5G Drivers THROUGHPUT GROWTH Peak (100 Mbps Gbps) and cell edge INCREASE OF CAPACITY FOR A GIVEN BANDWIDTH More users and more traffic by managing the complexity REDUCTION of END-to-END LATENCY Huge impacts on QoS/QoE for 5G services IMPROVEMENT OF COVERAGE Service continuity in all the sites of interest (both outdoor and indoor) 3

4 RAN architecture evolution towards cran / vran One possible evolution towards the cran / vran can be roughly summarized in the following phases: Phase 0: distributed BBU In most of current deployments the BBU is distributed in each site There could be a local connection (usually with CPRI) between BBU and RRU connected to the antennas with coaxial cables (non split architectures) The RRU are close to the antennas and connected with fibers to the BBU in the site Loose coordination via X2 in case of LTE system 4

5 RAN architecture evolution towards cran / vran Phase 1: BBU centralization and pooling (Centralized and Cloud RAN) in the first phase, the baseband unit is built with specialized HW and controls a variable number of cells (from ~tens to ~ hundreds). This architecture is suited for LTE Advanced system that will deploy non co-located Carrier Aggregation and cooperative multi-point (CoMP) functionalities. BBU resources pooling can be realized where the different HW resources can be dynamically allocated (e.g. in time and in space) to different cells and/or different RAT. BBU pooling improves the utilization and reliability of radio access networks, realizing a more efficient multi-rat joint radio operation. Interface of connection between RRH and BBU (fronthauling) could be CPRI. CPRI interface compression (based also on proprietary solutions) may allow to use also microwaves for fronthaul 5

6 RAN architecture evolution towards cran / vran Phase 2: RAN virtualization The final step of CRAN architectures is the virtual RAN architecture where a reconfigurable HW (e.g. general purpose Processing, GPP) is used with a significant number of controlled cells (~hundreds). The baseband resources in principle can be located in the same or different physical locations (the cloud ). This further evolution step will further facilitate the SW/HW reconfiguration among the different available RATs to dynamically adapt the processing resources to the traffic request, based on the SDR (Software Defined Radio) and NFV (Network Function Virtualization) paradigm. Different functional partitioning between BBU and RRU can enable bandwidth saving over the FH and lead to different virtualization solutions 6

7 Drivers for CRAN/VRAN deployment CAPEX/OPEX saving: Possible lower costs for rental (it depends on the type of contracts and installation), when BB are concentrated to the central office. Lower footprint and energy consumption coming from reduced air conditioning needs (when BB are located in a central location instead of multiple locations), but also from dynamic resource allocation and traffic load balancing. 7

8 Drivers for CRAN/VRAN deployment CAPEX/OPEX saving: Easier management and operation is made when the baseband of one or multiple systems is concentrated in less sites. For new sites, since RRU are functionally simpler, they probably require lower effort for site installation and management. 50%-70% OPEX reduction and 15%-47% CAPEX reduction based on different estimation from [1]. From [2] In case of virtual RAN the SDR will further make easier the management enabling the RAN upgrade by simple SW upgrade. Moreover virtual RAN architecture will potentially allow lower HW/SW cost for the operator due to the increased number of vendors (coming from the IT industry) and further market segmentation and competition. [1] AN ANALYSIS OF RAN COST-STRUCTURE BY NGMN ALLIANCE [2] C-RAN The Road Towards Green RAN, Whitepaper, 8

9 Drivers for CRAN/VRAN deployment Better performance thanks to the tx/rx coordination among the RRUs. Multi-site Carrier Aggregation (sites that share co-located BBUs) in case the operator has deployed LTE in multiple bands. This architecture requires: efficient mobility management algorithms (i.e. flexible secondary cells reconfiguration) High number of cells that can be controlled by the baseband Higher capacity gains are expected in scenarios with low cositing of different bands 9

10 Drivers for CRAN/VRAN deployment Better performance thanks to the tx/rx coordination among the RRUs. Inter-site CoMP: both downlink and uplink algorithms (up to Rel. 12) require BB centralization (intra enodeb solutions). Macro only solutions show good gains at cell edge for uplink CoMP (adressed by first implementations). Moderate-to-Low gains are expected from downlink CoMP Higher gains in HetNet scenarios (for example Stadium) due to the higher interference levels: 10

11 CRAN fronthauling transport challenges Current optical links between BBU and RRU is realized by means of proprietary interfaces: CPRI and OBSAI. For CPRI the typical value to link a LTE RRU 20 MHz MIMO 2x2 is 2,5 Gb/s. More efficient solutions are needed in the long term considering further evolution of the standard (higher order MIMO, carrier aggregation with more than 2 carriers) and HetNet deployments Even today with multi-sectors/multi-rat configurations different transport solutions must be considered Passive WDM is the main available technology used to multiply several optical connections over one fiber (pair) Up to tens CPRI links over a single fiber Passive no power Coloured SFP on both RRU and BBU sides Lower cost Active WDM Requires power Allow a better network monitoring Grey SFP on both RRU and BBU sides Both Ring or Bus topology Probably Vendor dependent More expensive 11

12 Alternative solutions for fronthauling towards Virtual RAN More efficient solutions can be considered, based on (flexible) functional split On Good the candidates other hand for the efficient implementation of such efficient functional splits makes simpler the implementation of the functional Central Unit splits on as x86 low hardware bandwidth and loose latency requirements on the fronthauling are expected 12

13 MEC and CRAN/VRAN Mobile edge computing (MEC), recently introduced by ETSI ISG MEC standardization group, permits to extend cloud platform for applications to the edge of the network (base stations), in order to improve the user experience (also thanks to the standardization of proper measurements and network APIs). This environment is characterized by ultra-low latency and high bandwidth as well as real-time access to radio network information that can be leveraged by applications and QoE platforms In order to allow operators to benefit as much as possible from their investment, it would be beneficial to introduce MEC solutions reusing the infrastructure and infrastructure management of NFV to the largest extent possible. 13

14 Architecture evolution towards Virtual RAN and 5G Big Data Centre hosting the VNFs for the for baseband the baseband + MEC Server (Metro level) MEC NR MME EPC HSS S/P-GW PCRF Web Application Server L3 Transport Network MEC NR WDM transport Radio Access Points 14

15 Takeways Network and RAN evolution, following the LTE evolution path towards 5G, is driven by several drivers (throughput, capacity, coverage and also energy efficiency). CRAN architecture is promising solution bringing several advantages in some scenarios: Better performances Reduced CAPEX/OPEX The final step of CRAN architectures is the virtual RAN architecture where a reconfigurable HW (e.g. general purpose) is used with a significant number of controlled cells, and BB resources in principle can be located in the same or different physical locations (the cloud). The processing power available at the edge of the network and possible new requirements enable the addition of mobile edge computing on top of network virtualization framework creating new opportunities for OTT and operators. Titolo della Relazione Nome del Relatore, Nome Struttura 15

16 Grazie Marco Caretti