Zere Ghebretensaé

Mobile broadband backhaul network migration from TDM to carrier ethernet

With the rollout of Long Term Evolution the capacity of the radio access network backhaul needs to be upgraded to 100-150 Mb/s. Nextgeneration mobile networks, such as LTE Release 10, will increase the requirement for backhaul capacity to gigabits per second. In order to increase network utilization and decrease operating expenses, carrier Ethernet transport infrastructure (MPLS and carrier grade Ethernet) will be deployed and maintained at a lower total cost of ownership than legacy TDM transport infrastructure. This article discusses different migration scenarios from the circuit-switched legacy backhaul networks toward packet-based networks.

Small-Cell Wireless Backhauling: A Non-Line-of-Sight Approach for Point-to-Point Microwave Links

In this paper we investigate the feasibility of using microwave frequencies for fixed non-line-of-sight wireless backhauling connecting small-cell radio base stations with an aggregation node in an outdoor urban environment, i.e. a typical heterogeneous network scenario. We study system level simulations for a point-to-point system where the wave propagation is based on diffraction over rooftops. We further investigate the effects of carrier frequency, interference, antenna height, rain, and tolerance to antenna alignment errors. It is found that the higher frequencies offer not only larger bandwidths but also higher antenna gains which would ideally work to their advantage. However, these advantages may be lost when taking antenna alignment errors and rain into account. Different frequencies simply have their different trade-offs.

Data Plane and Control Architectures for 5G Transport Networks

Next generation 5G mobile system will support the vision of connecting all devices that benefit from a connection, and support a wide range of services. Consequently, 5G transport networks need to provide the required capacity, latency, and flexibility in order to integrate the different technology domains of radio, transport, and cloud. This paper outlines the main challenges, which the 5G transport networks are facing and discusses in more detail data plane, control architectures, and the tradeoff between different network abstraction models.

Transmission solutions and architectures for heterogeneous networks built as C-RANs

A novel end-to-end transport network solution is proposed to meet the operational and technical challenges of heterogeneous networks built as C-RANs with centralized base band processing and CPRI links. The flexibility of the proposed architecture to support distributed architectures and Ethernet links is also described and the results of a C-RAN proof of concept demonstration are discussed. Substantiated by the evolution of key optical technologies, including a novel WDM-PON based solution, we conclude that backhaul and metro network strategies need to flexibly support both centralized and distributed radio baseband solutions, as well as being multiservice capable. Additionally, as a complement to fiber, we propose use of the 70/80 GHz frequency band (E-band) to provide high performance microwave links for both centralized and distributed architectures.

Software-defined networking in a multi-purpose DWDM-centric metro/aggregation network

A DWDM-centric solution is a promising approach to build a multiservice metro/aggregation network that meets the future requirements on capacity, cost, and energy-efficiency for both residential, business and mobile backhaul/fronthaul transport. We propose to use SDN to provide a suitable control mechanism of the optical and packet layers in the network. We also introduce a discovery unit, which detects newly connected DWDM clients and sets up the corresponding optical service. This is demonstrated for the case of a converged fixed and mobile infrastructure. We then describe how this network and control architecture can be used to provide services to different client network applications, where the details of the physical infrastructure are hidden through network virtualization.

Orchestration of RAN and Transport Networks for 5G: An SDN Approach

The fifth generation of mobile networks is planned to be commercially available in a few years. The scope of 5G goes beyond introducing new radio interfaces, and will include new services like low-latency industrial applications, as well as new deployment models such as cooperative cells and densification through small cells. An efficient realization of these new features greatly benefit from tight coordination among radio and transport network resources, something that is missing in current networks. In this article, we first present an overview of the benefits and technical requirements of resource coordination across radio and transport networks in the context of 5G. Then, we discuss how SDN principles can bring programmability to both the transport and radio domains, which in turn enables the design of a hierarchical, modular, and programmable control and orchestration plane across the domains. Finally, we introduce two use cases of SDN-based transport and RAN orchestration, and present an experimental implementation of them in a testbed in our lab, which confirms the feasibility and benefits of the proposed orchestration.

Data plane and control architectures for 5G transport networks

Next generation 5G mobile system will support the vision of connecting all devices that benefit from a connection. Transport networks need to support the required capacity, latency and flexibility. This paper outlines how 5G transport networks will address these requirements.

Optical transport and challenges in the Networked Society

The fifth generation of mobile networks (5G) is the next major phase of mobile telecommunications that will enable the Networked Society. We describe the challenges and role of optical transport in the Networked Society. The paper covers the role of optical transport for 5G radio and SDN/NFV and the impact of integrated photonics with promise of low-cost DWDM which could serve as the basis for 5G transport satisfying requirements on performance, low cost and flexibility.

Low-cost WDM cross-connects based on the multi-directional wavelength selective switch

We present a performance characterization of the MD-WSS. Furthermore, two low-cost OXCs (6×6 and 8×8) built by interconnecting only two 1:4 MD-WSSs are proposed and experimentally validated.

Use cases for flexible 5G transport networks

The 5th generation of mobile networks (5G) will provide the foundation for the Networked Society. 5G networks will not only provide higher capacity but also support completely new services/applications and new business models. The transport network will need to support 5G radio and potentially new deployment models. It is believed that an important requirement on the transport will be increased flexibility. We present use cases for flexible 5G transport networks such as dynamic capacity scaling of radio access networks.