5G-crosshaul: an SDN/NFV integrated fronthaul/backhaul transport network architecture

This article proposes an innovative architecture design for a 5G transport solution (dubbed 5G-Crosshaul) targeting the integration of existing and new fronthaul and backhaul technologies and interfaces. At the heart of the proposed design lie an SDN/NFV-based management and orchestration entity (XCI), and an Ethernet-based packet forwarding entity (XFE) supporting various fronthaul and backhaul traffic QoS profiles. The XCI lever-ages widespread architectural frameworks for NFV (ETSI NFV) and SDN (Open Daylight and ONOS). It opens the 5G transport network as a service for innovative network applications on top (e.g., multi-tenancy, resource management), provisioning the required network and IT resources in a flexible, cost-effective, and abstract manner. The proposed design supports the concept of network slicing pushed by the industry for realizing a truly flexible, sharable, and cost-effective future 5G system.This work has been funded by the EU H2020 project “5G- Crosshaul: The 5G Integrated Fronthaul/Backhaul” (Grant no. 671598)

5G transport network requirements for the next generation fronthaul interface

To meet the requirements of 5G mobile networks, several radio access technologies, such as millimeter wave communications and massive MIMO, are being proposed. In addition, cloud radio access network (C-RAN) architectures are considered instrumental to fully exploit the capabilities of future 5G RANs. However, RAN centralization imposes stringent requirements on the transport network, which today are addressed with purpose-specific and expensive fronthaul links. As the demands on future access networks rise, so will the challenges in the fronthaul and backhaul segments. It is hence of fundamental importance to consider the design of transport networks alongside the definition of future access technologies to avoid the transport becoming a bottleneck. Therefore, we analyze in this work the impact that future RAN technologies will have on the transport network and on the design of the next generation fronthaul interface. To understand the especially important impact of varying user traffic, we utilize measurements from a real-world 4G network and, taking target 5G performance figures into account, extrapolate its statistics to a 5G scenario. With this, we derive both per-cell and aggregated data rate requirements for 5G transport networks. In addition, we show that the effect of statistical multiplexing is an important factor to reduce transport network capacity requirements and costs. Based on our investigations, we provide guidelines for the development of the 5G transport network architecture.Peer ReviewedPostprint (published version

Transport Network Design for FrontHaul

International audienceThe evolution of LTE and advent of 5G networks increases further the bandwidth requirements for Radio Access Network (RAN). In parallel, the deployment of Centralized RAN architecture raises new challenges on the FrontHaul network. The inflexibility of the legacy Common Public Radio Interface (CPRI) is the primary challenge to Virtualized RAN deployments, and there is currently a strong trend towards the use of packetized transport methods, together with flexible split RAN based architectures. Functional splits within the real-time functions of the RAN have very stringent requirements on latency and jitter. This paper analyzes the jitter produced in the switching nodes of the FrontHaul network, and proposes dimensioning rules

Fronthaul evolution: From CPRI to Ethernet

It is proposed that using Ethernet in the fronthaul, between base station baseband unit (BBU) pools and remote radio heads (RRHs), can bring a number of advantages, from use of lower-cost equipment, shared use of infrastructure with fixed access networks, to obtaining statistical multiplexing and optimised performance through probe-based monitoring and software-defined networking. However, a number of challenges exist: ultra-high-bit-rate requirements from the transport of increased bandwidth radio streams for multiple antennas in future mobile networks, and low latency and jitter to meet delay requirements and the demands of joint processing. A new fronthaul functional division is proposed which can alleviate the most demanding bit-rate requirements by transport of baseband signals instead of sampled radio waveforms, and enable statistical multiplexing gains. Delay and synchronisation issues remain to be solved

5G-Crosshaul: an SDN/NFV control and data plane architecture for the 5G integrated Fronthaul/Backhaul

This paper presents the control and data plane architecture design for a 5G transport solution (5G-Crosshaul) with the aim of integrating the fronthaul and backhaul network segments in a common transport stratum. The control plane relies on the Software-defined networking/Network Functions Virtualization concept to control and orchestrate the different elements of the network (the 5G-Crosshaul control infrastructure). The data plane is based on an mixed optical/packet-based forwarding entity (the 5G-Crosshaul forwarding element) that leverages the benefits of optical passthrough with the statistical multiplexing of packet-based transmission, working on top of a common frame format for both, fronthaul, and backhaul traffic (the 5G-Crosshaul common frame). In addition to the main architecture design, this work includes the impact of providing multi-tenancy support into the architecture of the overall system, in order to share the costs of building and operating the infrastructure among different operators. This architecture opens the 5G transport network as a service for innovative network applications on top (such as multi-tenancy, and resource management), provisioning the required network and IT resources in a flexible, cost-effective, and abstract manner. The proposed design supports the concept of network slicing pushed by the industry for realizing a truly flexible, sharable, and cost-effective future 5G system.This work has been funded by the EU H2020 project “5GCrosshaul: The 5G Integrated fronthaul/backhaul” (grant no. 671598)

Will SDN be part of 5G?

For many, this is no longer a valid question and the case is considered settled with SDN/NFV (Software Defined Networking/Network Function Virtualization) providing the inevitable innovation enablers solving many outstanding management issues regarding 5G. However, given the monumental task of softwarization of radio access network (RAN) while 5G is just around the corner and some companies have started unveiling their 5G equipment already, the concern is very realistic that we may only see some point solutions involving SDN technology instead of a fully SDN-enabled RAN. This survey paper identifies all important obstacles in the way and looks at the state of the art of the relevant solutions. This survey is different from the previous surveys on SDN-based RAN as it focuses on the salient problems and discusses solutions proposed within and outside SDN literature. Our main focus is on fronthaul, backward compatibility, supposedly disruptive nature of SDN deployment, business cases and monetization of SDN related upgrades, latency of general purpose processors (GPP), and additional security vulnerabilities, softwarization brings along to the RAN. We have also provided a summary of the architectural developments in SDN-based RAN landscape as not all work can be covered under the focused issues. This paper provides a comprehensive survey on the state of the art of SDN-based RAN and clearly points out the gaps in the technology.Comment: 33 pages, 10 figure