While I am critical of the C-RAN approach, there are many vendors and engineers & architects within these vendors who are for or against this technology. I am going to leave the benefits and drawbacks of C-RAN in light of new developments (think Moore's law) for some other day.
earlier post explains the concept of Fronthaul and Backhaul for anyone who may not be aware. As data speeds keep on increasing with 4G, 4.5G, 4.9G, 5G, etc. it makes much more sense to use Fiber for Fronthaul. Dark fiber would be a far better choice than a lit one.
One thing that concerned me was what happens in case of MIMO or massive MIMO in 5G. Would we need multiple Fronthaul/Fibre or just a single one would do. After having some discussions with industry colleagues, looks like a single fiber is enough.
NTT presentation illustrates how WDM (Wavelength Division Multiplexing) can be used to send different light wavelengths over a single fiber thereby avoiding the need to have multiple of these fibers in the fronthaul.
There are 2 different projects ongoing to define 5G Fronthaul & Backhaul.
The first of these is 5G Crosshaul. Their website says:
The 5G-Crosshaul project aims at developing a 5G integrated backhaul and fronthaul transport network enabling a flexible and software-defined reconfiguration of all networking elements in a multi-tenant and service-oriented unified management environment. The 5G-Crosshaul transport network envisioned will consist of high-capacity switches and heterogeneous transmission links (e.g., fibre or wireless optics, high-capacity copper, mmWave) interconnecting Remote Radio Heads, 5GPoAs (e.g., macro and small cells), cloud-processing units (mini data centres), and points-of-presence of the core networks of one or multiple service providers. This transport network will flexibly interconnect distributed 5G radio access and core network functions, hosted on in-network cloud nodes, through the implementation of: (i) a control infrastructure using a unified, abstract network model for control plane integration (Crosshaul Control Infrastructure, XCI); (ii) a unified data plane encompassing innovative high-capacity transmission technologies and novel deterministic-latency switch architectures (Crosshaul Packet Forwarding Element, XFE).
The second is 5G XHaul. Their website says:
- Dynamically programmable, high capacity, low latency, point-to-multipoint mm-Wave transceivers, cooperating with Sub-6 GHz systems;
- A Time Shared Optical Network offering elastic and fine granular bandwidth allocation, cooperating with advanced passive optical networks;
- A software-defined cognitive control plane, able to forecast traffic demand in time and space, and the ability to reconfigure network components.
- Developing novel converged optical/wireless architectures and network management algorithms for mobile scenarios;
- Introduce advanced mm-Wave and optical transceivers and control functions;
- Support the development of international standards through technical and technoeconomic contributions.
It remains to be seen if C-RAN will play a big role in 5G. If yes how much of Crosshaul and XHaul will help.
- Fronthaul and backhaul: Look out, a fusion is coming! - Alan Carlton, Interdigital
- RAN Evolution Project: Backhaul and Fronthaul Evolution - NGMN
- Examining the fronthaul opportunities for future radio access - Shigeru Kuwano, NTT Access Network Service Systems
- 5 Things You Need to Know About vRAN: “vRAN architecture: centralize or distribute” - Amir Atai, Parallel Wireless
- 5G-XHaul project looks at WDM-PON for mobile fronthaul, backhaul - Lightwave
- Why WDM is essential in C-RAN fronthaul networks? - Ultra high CPRI link capacity - Steve Shin and Dr. Harrison J. Son, Netmanias
- Fronthaul Evolution Toward 5G: Standards and Proof of Concepts