An overview of the CPRI specification and its application to C-RAN-based LTE scenarios

The CPRI specification has been introduced to enable the communication between radio equipment and radio equipment controllers, and is of particular interest for mobile operators willing to deploy their networks following the novel cloud radio access network approach. In such a case, CPRI provides an interface for the interconnection of remote radio heads with a baseband unit by means of the so-called fronthaul network. This article presents the CPRI specification, its concept, design, and interfaces, provides a use case for fronthaul dimensioning in a realistic LTE scenario, and proposes some interesting open research challenges in the next-generation 5G mobile network.The authors would like to acknowledge the support of projects CRAMnet (grant no. TEC2012-38362-C03-01) and EU H2020 5G-Crosshaul Project (grant no. 671598) to the development of this work.European Commissio

Encapsulation Techniques and Traffic Characterisation of an Ethernet-Based 5G Fronthaul

This paper first overviews how, in the 5G Next Generation Radio Access Network (NG-RAN), the Next generation NodeB (gNB) functions are split into Distributed Unit (DU) and Central Unit (CU). Then it describes the proposed fronthaul transport solutions, such as Common Packet Radio Interface (CPRI), eCPRI, IEEE P1914.3 and their relationship with the Ethernet protocol. Finally, a characterisation of the traffic generated by the fronthaul is presented. Such characterisation may guide in the selection of the right network for fronthaul transport.This work has been partially funded by the EU H2020 “5G-Transformer” Project (grant no. 761536)

Dataplane Measurements on a Fronthaul and Backhaul integrated network

Future transport networks serving next generation accesses are expected to carry both fronthaul (FH) and backhaul (BH) traffic simultaneously. This new concept of network which integrates the FH and BH traffic over the same transport substrate is called Crosshaul. A Crosshaul network will use heterogeneous technologies, such as fiber, mmWave, or microwave, and selects the most appropriates ones depending on the use case. Moreover, the softwarization/virtualization trend on the networking industry indicates that Virtual Network Functions (VNFs) will process and exchange both BH and FH data plane traffic. This paper presents performance measurements on promising technologies for the implementation of a Crosshaul network. We investigate to which extent the requirements to carry FH traffic are satisfied by mmWave links, software and multi-layer hardware switches

A Shared-Path Shared-Compute Planning Strategy for a Resilient Hybrid C-RAN

One key challenge in 5G networks is to guarantee the survivability of services in the event of failures. This paper focuses on the hybrid cloud radio access network (H-CRAN) architecture. The proposed strategy guarantees survivability in the presence of failures affecting nodes/links in the midhaul segment (i.e., connecting the radio aggregation unit (RAU) nodes to their respective radio cloud center (RCC) nodes) as well as compute resources (i.e., servers) in the RCC nodes. In the envisioned strategy each RAU node is connected to a primary and a backup RCC node (i.e., with backup compute resources) via two node disjoint connectivity paths in the midhaul. The proposed strategy, called Shared-Path Shared-Compute Planning (SPSCP), lowers the overall design cost by trying to share as much as possible backup connectivity and compute resources among RAU nodes. This is made possible by introducing a shareability metric early into the RCC node selection process so that the chance of sharing backup resources is maximized. Simulation results show that the SPSCP strategy can lead to up to 28% cost savings when compared to conventional resilient design strategie

36 Gb/s Narrowband photoreceiver for mmwave analog radio-over-fiber

Migrating toward higher frequencies and densification of the communication cells are two key enablers for increased wireless data rates. To make these trends economically viable, centralized architectures based on radio-over-fiber (RoF) are explored. This article describes the design of a photoreceiver that can be applied at the remote radio head in a 28 GHz analog RoF link. The devised photoreceiver comprises a Ge-on-Si photodetector and co-designed GaAs low noise amplifier offering 24 dB gain, corresponding to 224 V/W external conversion gain, over a 3-dB bandwidth between 23.5 and 31.5 GHz. The associated noise figure is 2.1 dB and an output referred third order intercept point up to 26.5 dBm can be obtained with a power consumption of 303 mW. Two possible applications are demonstrated in this article. First, the photoreceiver is tested in a 5G New Radio environment resulting in rms-EVM values below 2.46/3.47% for 100/400-MBaud 16-QAM transmission over the 24.25-29.5 GHz band. Secondly, very high data rates can also be supported, demonstrated by a 36 Gb/s link with an rms-EVM of 5.2%

Experimental measurements of a joint 5G-VLC communication for future vehicular networks

One of the main revolutionary features of 5G networks is the ultra-low latency that will enable new services such as those for the future smart vehicles. The 5G technology will be able to support extreme-low latency. Thanks to new technologies and the wide flexible architecture that integrates new spectra and access technologies. In particular, Visible Light Communication (VLC) is envisaged as a very promising technology for vehicular communications, since the information can flow by using the lights (as traffic-lights and car lights). This paper describes one of the first experiments on the joint use of 5G and VLC networks to provide real-time information to cars. The applications span from road safety to emergency alarm