Optical switch WC-Pool (in a data centre) BBU-pool RAT 1 BBU-pool RAT 2 BBU-pool RAT N Mobile Cloud Networking FP7 European Project: Radio Access Network as a Service Dominique Pichon (Orange) 4th Workshop on Mobile Cloud Networking 19.06.2014, Lisboa, Portugal
Outline Motivations and Objectives MCN Quick Overview Challenges for an on demand RAN A PaaS Approach for RANaaS Conclusion 2012-2015 MCN. All rights reserved. / Page 2
Outline Motivations and Objectives MCN Quick Overview Challenges for an on demand RAN A PaaS Approach for RANaaS Conclusion 2012-2015 MCN. All rights reserved. / Page 3
Motivations for Virtualizing Networks Flexible Network Operations Flexible resource allocation analytics tools for dimensioning the network Automated Network operation auto-scaling less trouble shooting by use of automatic configurations and isolation between tenants Faster Speed of Time to Market Cost efficiency sharing hardware => reduced power and space consumption non proprietary hardware installation, maintenance and removal costs reduction flexible and automated network operations multi-tenancy 2012-2015 MCN. All rights reserved. / Page 4
Motivations: Focus on RAN Today s Radio Access Networks (RANs) have a large number of Base Stations (BSs), of multiple Radio Access Technologies (RATs), of high power consumption and cost (CAPEX/OPEX). Explosive capacity needs vs. falling revenues per user. RAN is typically dimensioned for the busy hour; still, offered load varies drastically, with large periods of low utilisation. BSs BSs 2012-2015 MCN. All rights reserved. / Page 5 BSs Backhaul Network Core Network
Outline Motivations and Objectives MCN Quick Overview Challenges for an on demand RAN A PaaS Approach for RANaaS Conclusion 2012-2015 MCN. All rights reserved. / Page 6
The EU FP7 European Mobile Cloud Networking Project European collaborative project FP7. Started in Nov. 2012. End: Oct. 2015 http://www.mobile-cloud-networking.eu/site/ Who? Objective: to offer on demand a mobile network 2012-2015 MCN. All rights reserved. / Page 7
MCN FP7 Objective: RAN as a Service To offer a cloud-based RAN as a Service (RANaaS): Heterogeneous, virtualised and multi-tenant RAN, following cloud principles (infrastructure sharing, elasticity, on-demand, pay-as-you-go). Dynamically adapted to geographic and temporal load variations and traffic type. Centralised RAN processing architecture, based on virtualised pools of Base Band Units (BBU-pools) on datacentres. Flexible relationship between Remote Radio Heads (RRHs) and BBUs, linked by a high bandwidth and low-latency optical fronthaul network. RRHs RRHs Central Office BBU-pool RAT 1 RRHs BBU-pool RAT 2... BBUs 2012-2015 MCN. All rights reserved. / Page 8 Fronthaul Transport Network Datacentre Backhaul Network Core Network
Outline Motivations and Objectives MCN Quick Overview Challenges for an on demand RAN A PaaS Approach for RANaaS Conclusion 2012-2015 MCN. All rights reserved. / Page 9
Challenges for RANaaS Fronthaul transport network (between BBUs and RRHs) High bit-rate CPRI links: Site with 3 RRHs (LTE, 20MHz) requires 7.4 Gbit/s link. Low latency: Maximum round trip delay of 150µs (~15 km optical fibre). Jitter and synchronisation: Stringent requirements for frequency and phase synchronisation Real-time performance base stations requires strict real time performance e.g., air interface LTE L2 packets to be handled in 3.66 ms 2012-2015 MCN. All rights reserved. / Page 10
RRHs RRHs RRHs D-RoF Optical switch WC-Pool (in a data centre) BBU-pool RAT 1 BBU-pool RAT 2 BBU-pool RAT N Challenges for RANaaS Offer cloud based multi-tenant on demand RANaaS: Offer SLA-guaranteed connectivity to multiple tenants (MVNOs) through an elastic on-demand allocation of resources. on demand => dynamic spectrum management Detect and predict resources usage to optimize the offered services. Radio Access Network Core Network MVNO Cheap Radio resources Remote Radio Heads (RRHs) Fibre optic resources Computational resources Best effort for all users MVNO Gold 2 Mbps to all users Virtual radio resources 2012-2015 MCN. All rights reserved. / Page 11 RRHs Radio Interface RRHs Fronthaul Transport Network BBU-pool RAT 1 BBU-pool RAT 2 Datacentre... BBUs Backhaul Transport Network
Challenges for virtualized RAN Elasticity by means of horizontal scalability and load balancing LTE air interface protocols are not RESTful =>so you cannot simply add an HTTP load balancer and add VM hosting http servers for handling LTE workload Load Balancer Worker Worker Worker =>need for redesigning the base station software to make it horizontally scale 2012-2015 MCN. All rights reserved. / Page 12
Outline Motivations and Objectives MCN Quick Overview Challenges for an on demand RAN A PaaS Approach for RANaaS Conclusion 2012-2015 MCN. All rights reserved. / Page 13
A Platform as a Service for Mobile Network PaaS allows service providers to host and execute web applications using third-party managed servers e.g., Google App Engine, OpenShift A Mobile Network using PaaS allows mobile network service providers to host and execute network functions using a third party infrastructure 2012-2015 MCN. All rights reserved. / Page 14
Platform as a Service by Google A user uses the service via the web --e.g., a web app to manage post-its with your wife/husband/child(ren) the developer -designs the service using the Google SDK and pushes the related code to Google App Engine Google - hosts the application software, runs it, provides means to improve it and log s on the service delivery - and charges you [Octo.com] 2012-2015 MCN. All rights reserved. / Page 15
Platform as a Service for RANaaS 2012-2015 MCN. All rights reserved. / Page 16
RANaaS: Architecture Design cloud-based RANaaS architecture, supported by a set of functional elements: based on MCN architecture reference model Service manager (SM): interface to client, Service Orchestrator (SO): In charge of the RANaaS lifecycle Cloud Controller (CC): Providing physical resources for RANaaS using support services Monitoring, charging, SLA management, analytics Plus RAN virtualized network functions LTE Base station protocol stacks broken down to enable fine mapping between layers processing requirements and physical resources elasticity by balancing the load from UEs on different servers 2012-2015 MCN. All rights reserved. / Page 17
RANaaS: Architecture 2012-2015 MCN. All rights reserved. / Page 18
RANaaS: Service lifecycle Design Disposal (destroy) Deployment (load components for an SLA chosen by a client) Runtime management (scale up/down) Provisioning (customise) 2012-2015 MCN. All rights reserved. / Page 19
MCN architecture under development RANaaS components designed by RANP to instantiate RAN on demand Support services used by RANP Managing lifecycle of base stations Use to configure the base stations VNFs deployed by RANP for its EEU 2012-2015 MCN. All rights reserved. / Page 20
Outline Motivations and Objectives MCN Quick Overview Challenges for an on demand RAN A PaaS Approach for RANaaS Conclusion 2012-2015 MCN. All rights reserved. / Page 21
Conclusion Cloud-based RAN is a novel architecture that aims at bringing cost and efficiency benefits from the cloud computing model. MCN aims at offering elastic, scalable, and on-demand RANaaS, dynamically adapted to geographic and temporal load variations. It faces several challenges, regarding: Fronthaul Radio resource management Real-time performance Scalability The approach is being developed for further evaluation 2012-2015 MCN. All rights reserved. / Page 22
Thank You
Fronthaul: Scenarios and Solutions Fibre availability is already a requirement in Orange France LTE backhaul: 90% of sites in dense areas have fibre. 96% of links are shorter than 10km. In urban areas, up to 28 cell sites are connected to one Central Office. Several solutions can be considered for the fronthaul: One fibre per RRH. One fibre per site, shared by RRHs with Wavelength Division Multiplexing (WDM). Alternatively, microwave links can be used for small radio sites. 2012-2015 MCN. All rights reserved. / Page 24
D-RoF Optical switch WC-Pool (in a data centre) BBU-pool RAT 1 BBU-pool RAT 2 Fronthaul: Challenges Fronthaul transport network (between BBUs and RRHs): Digital Radio over Fibre (D-RoF). Using typically the Common Public Radio Interface (CPRI) standard. Digitation requires high bit-rate CPRI links: Site with 3 RRHs (LTE, 20MHz) requires 7.4 Gbit/s link. Site with 15 RRHs (LTE-A (2 bands), 3G (2 bands), 2G (1 band)) requires up to 20Gbit/s link. Low latency: Maximum round trip delay of 150µs (~15km optical fibre). Jitter and synchronisation: Stringent requirements for frequency and phase synchronisation. RRHs RRHs RRHs D-RoF Optical switch/router Fronthaul Transport Network BBU-pool RAT 1 BBU-pool RAT 2 Centra Office (datacentre)... BBUs 2012-2015 MCN. All rights reserved. / Page 25
Fronthaul: Research Impact of Mobile Cloud Networking on Fronthaul. Dimensioning and optimisation of the optical link between the BBU-pools and RRHs: Based on realistic network configurations. To optimise the architecture and have an end-to-end picture. Reduce required bit-rates on CPRI links: Several propositions for function splitting between RRH and BBU will be taken into account. Support interoperability, multi-technology (2/3/4G, WiFi) and RAN sharing between different operators. 2012-2015 MCN. All rights reserved. / Page 26
Load Balancing: Motivation Scenario With few users, only 3 RRH-BBU are sufficient to cover the service area and provide the requested capacity. Control Plane Controller BBUpool 1 BBU Plane BBUpool 1 BBU3 (20% load) BBU2 (30% load) RRH Plane RRH1 RRH2 RRH3 BBU1 (20% load) End-user Plane 2012-2015 MCN. All rights reserved. / Page 27
Load Balancing: Motivation Scenario When the number of users increases, more RRHs are activated, and associated BBUs instantiated on a single BBU-Pool, to provide the requested capacity. Control Plane BBU Plane RRH Plane RRH3 RRH2 Controller BBUpool 1 RRH4 RRH5 RRH1 RRH6 RRH7 BBUPool 1 BBU7 (10% load) BBU6 (10% load) BBU5 (10% load) BBU4 (10% load) BBU3 (10% load) BBU2 (10% load) BBU1 (10% load) End-user Plane 2012-2015 MCN. All rights reserved. / Page 28
Load Balancing: Motivation Scenario With a highly loaded network, some BBUs must be instantiated on a different BBU-Pool, as the load exceeds the BBU-Pool capacity. BBUPool 2 Control Plane Controller BBUPool 1 BBU4 (80% load) BBU3 (70% load) BBU2 (80% load) BBU Plane BBUpool 2 BBUpool 1 BBU7 (70% load) BBU6 (60% load) BBU1 (60% load) RRH Plane RRH3 RRH2 RRH4 RRH1 RRH7 RRH5 RRH6 BBU5 (80% load) End-user Plane 2012-2015 MCN. All rights reserved. / Page 29
Load Balancing: Challenges Virtualisation of a sub-set of BBU functions, which can be scaled up and down. Quantification of the relation between load and processing needs. Map user load into required processing of virtualised BBU functions. Balance RAN processing load between BBU-pools: Dimension the number of cell sites one BBU-pool can manage. Account for temporal and geographical variations of load. Take into consideration radio, fronthaul and datacentre capabilities and constraints, as well as SLAs (and associated QoS requirements). Efficiently allocate processing resources (locally or remotely). Balance load between multiple RATs. 2012-2015 MCN. All rights reserved. / Page 30