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

A Flexible, Ethernet Fronthaul for 5th Generation Mobile and Beyond

Using Ethernet in the fronthaul can deliver the statistical multiplexing gains offered by the new functional splits proposed for the radio access network, but latency and delay variations are challenges that must be overcome

Comparison of Digital Signal Processing Approaches for Subcarrier Multiplexed 5G and Beyond Analog Fronthaul

Analog fronthaul transport architectures with digital signal processing at the end stations are promising as they have the potential to achieve high spectral efficiencies, increased flexibility and reduced latency. In this paper, two digital techniques for frequency domain multiplexing/de-multiplexing large numbers of channels are contrasted: one operates on the pre-Inverse Fast Fourier Transform (IFFT) “frequency-domain” samples while the other does so on the post-IFFT “time-domain” samples. Performance criteria including computational complexity and sampling rate requirements are used in the comparison. Following modeling and simulation of the techniques, implemented within a radio-over-fiber transport architecture, error vector magnitude performance estimates are obtained. These results show that each technique has performance advantages under specific channel transport scenarios

Bidirectional 2.5-Gb/s WDM-PON Using FP-LDs Wavelength-Locked by a Multiple-Wavelength Seeding Source Based on a Mode-Locked Laser

Topic "Networks and Systems"International audienceWe experimentally investigate the operation of a cost-effective wavelength-division-multiplexed passive optical network (WDM-PON) based on wavelength-locked Fabry-Pérot laser diodes (FP-LDs). A single quantum-dash passively mode-locked laser (QD-MLL) is combined with an arrayed waveguide grating in WDM-PON architecture to provide a low-noise, coherent multiwavelength seeding source to injection-lock the FP-LDs for both downstream and upstream. The results show that the QD-MLL-injected FP-LD has the same performance when compared to the case of injection-locking by a low-noise external cavity laser. Error-free bidirectional transmission over 25 km for 16 channels with 42.7-GHz channel spacing is demonstrated at 2.5 Gb/s in the C-band and an optical budget higher than 30 dB is reached

Subsystems for future access networks

Current evolution and tendencies of Telecom Networks in general and more specifically optical Metro and Access Networks and their convergence are reported. Based on this evolution, a set of research lines are foreseen regarding subsystems and devices as: high speed optical sources, modulators and receivers, for the next generation of Passive Optical Networks. The ICT project EURO-FOS is achieving European level cooperative research among academia and industry, enabling future telecommunication networks

10-Gb/s Operation of a Colorless Self-Seeded Transmitter Over More Than 70 km of SSMF

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Concepts and requirements for the Ethernet-based evolved fronthaul

The use of Ethernet in the fronthaul permits convergence and exploitation of statistical multiplexing gains of the new interfaces, but minimum latency and latency variation requirements may become challenging. The techniques proposed to meet these challenges are summarized

Boosting 5G Through Ethernet: How Evolved Fronthaul Can Take Next-Generation Mobile to the Next Level

Current approaches to the fronthaul for centralized- or Cloud-Radio Access Networks (C-RANs) need to be revised to meet the requirements of next-generation mobile networks. There are two major challenges: first, fronthaul signals need to be transported over public fixed access networks, such as passive optical networks (PONs), typically sharing them with other services; second, higher data rates must be catered for due to larger radio bandwidths and greater use of multi-antenna techniques, such as massive MIMO. Using Ethernet as a new transport protocol for the fronthaul allows statistical multiplexing and enables convergence between fixed and mobile services. This new approach more easily benefits from common developments being made for service level agreements, functional virtualization and software-defined networking. Higher data rates will be supported by the move to new, and possibly flexible, functional split points inside the radio access network (RAN) protocol stack of the processing located in the central and distributed units, as is being investigated by a number of bodies. However, there are technical challenges with regard to latency and packet delay variation. This article summarizes the benefits of an Ethernet-based fronthaul for the next generation of mobile networks, its main challenges and how these may be overcome

SARDANA: an all-optical access-metro WDM/TDM-PON

A new optical access network, named “Scalable Advanced Ring-based passive Dense Access Network Architecture” (SARDANA), is presented. It transparently integrates WDM metro and TDM PON access technologies, implementing ring protection, 100 km reach and up to 1024 users served at 10 Gb/s, with passive highly-shared infrastructure. The introduced innovations are hybrid ring/tree WDM/TDM Passive Optical Network (PON) architecture; a resilient remote node (RN), which is distantly pumped from the Optical Line Terminal (OLT); and a reflective ONU (Optical Network Unit); as well as an enhanced Medium Access Control (MAC) protocol.Postprint (published version

Colorless Components for WDM-based Optical Access Networks

Section B "PHOTONICS & LASERS AND APPLICATIONS" [B-45]International audienceThis paper presents our work carried out in the colorless-component technologies for high bit-rate optical access networks, which are based on WDM-PON (wavelength division multiplexed passive optical networks). The colorless concept consists in using identical and wavelength-independent components that will act as the generic transmitter in WDM-PON systems. The transmitted wavelength is imposed, for each colorless component, by an external optical signal. Our studies include two types of colorless components: The Injection-Locked Fabry-Perot laser (IL-FP) and the Reflective Electro-Absorption Modulator integrated with a Semiconductor Optical Amplifier (REAM-SOA). For the IL-FP, the properties of the component strongly depend on the injected optical signal. We demonstrate the improvement by injection-locking of the laser's performances in terms of intensity noise, chirp and bandwidth. For the REAM-SOA, the static properties such as reflection gain and noise characteristic are examined. We demonstrate the feasibility of the REAM-SOA in a transmission experiment in a PON configuration at 10 Gbps with up to 25 km of SMF, using remote modulation technique