47 research outputs found
Fronthaul-Constrained Cloud Radio Access Networks: Insights and Challenges
As a promising paradigm for fifth generation (5G) wireless communication
systems, cloud radio access networks (C-RANs) have been shown to reduce both
capital and operating expenditures, as well as to provide high spectral
efficiency (SE) and energy efficiency (EE). The fronthaul in such networks,
defined as the transmission link between a baseband unit (BBU) and a remote
radio head (RRH), requires high capacity, but is often constrained. This
article comprehensively surveys recent advances in fronthaul-constrained
C-RANs, including system architectures and key techniques. In particular, key
techniques for alleviating the impact of constrained fronthaul on SE/EE and
quality of service for users, including compression and quantization,
large-scale coordinated processing and clustering, and resource allocation
optimization, are discussed. Open issues in terms of software-defined
networking, network function virtualization, and partial centralization are
also identified.Comment: 5 Figures, accepted by IEEE Wireless Communications. arXiv admin
note: text overlap with arXiv:1407.3855 by other author
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Towards efficient and reconfigurable next-generation optical fronthaul networks for massive MIMO
This paper summaries our recent research on digital radio over fibre (DRoF) based optical fronthaul links and
experimentally demonstrates a novel last-mile wireless coverage system incorporating data compression, time-division
multiplexing (TDM) based packetization, and wavelength division multiplexing (WDM) based optical transmission.
Compression reduces the fronthaul data rate required per service by a factor of 3 when compared with the common public
radio interface (CPRI) standard, enabling efficient radio resource distribution over optical fibre infrastructure. The new
packetization mechanism and WDM architecture enable fully reconfigurable resource allocation in a fronthaul network for
20MHz-bandwidth RF inputs with 64x64 MIMO carried over an aggregated compressed optical data rate of 32Gbps using
4 wavelengths. The experimental results show over 40dB RF dynamic range with < 8% error value magnitude (EVM) for
the 64 quadrature amplitude modulation (64-QAM) input signals across all the WDM channels while the lowest EVM is
less than 2%. Meanwhile, this field-programmable gate array (FPGA) based DRoF system allows flexible, software
definable and easy-scalable dynamic antenna resource allocatio
Overview on Optical Fronthauling Technologies for Fixed-Mobile Convergence
We present in this Chapter an overviewof optical fronthauling technologies
for fixed-mobile convergence in next generation 5G access networks. The Chapter
first introduces the general concept of Cloud Radio Access Network, or C-RAN, then
it presents the most common proposals for fronthauling, based on Digitized Radioover-
Fiber, or D-RoF, according to the CPRI or OBSAI standards. The Chapter then
prosecutes by presenting the very recent evolutions of D-RoF toward the "functional
split" paradigm, as already available in the latest releases of the CPRI specifications.
Finally, some recent research trends towards Analog RoF are presented. The Chapter
is intentionally written in a tutorial way, to be used by newcomers in this field. It
anyway also reports a vast set of bibliographic references to guide the interested
reader toward more detailed technical presentations