Confused about the various CRAN models? Mobile Experts looks to simplify CRAN and explain concepts behind various other RAN plans
Imagine the possibility of a completely flexible mobile network where capacity can be allocated magically by software. That’s the dream that is summarized as “cloud radio access network”… but when it comes to building the hardware, what does it really mean?
For true flexibility, we need a widespread radio network that connects to a data center where commercial servers do the heavy lifting. Ideally, an off-the-shelf server would run software to execute all of the baseband processing required for the mobile network. Achieving this vision would not only change the entire process of planning, deploying and operating wireless networks, but also would fundamentally alter the ecosystem and relationship between the different players.
To demystify cloud RAN, we adopted the following terminologies to describe different RAN architectures based on the extent of centralization and virtualization of baseband processing:
Cloud RAN
A generic term that has lost its meaning at a technical level. In general, cloud RAN denotes a system that includes aspects of both centralized baseband processing and virtualization.
Virtual RAN
A fully centralized and virtualized architecture where general-purpose processors and servers run the air interface protocol stack. VRAN holds the most potential for disruption, but is also the most difficult to realize although it is becoming feasible due to new generation of processors and implementation approaches as recently demonstrated.
Hybrid RAN
A split-baseband architecture where some modem functions are split between GPPs in a central location and other type of devices at the cell site. Hybrid RAN optimizes cost and performance, but does not have the same disruptive potential as virtual RAN. Multiple such implementations will be available depending on the architectural split.
Centralized RAN
An architecture that is similar to hybrid RAN, but with the difference that no GPPs are used. The split functionality of baseband between the central and remote sites allows coordination of resources to improve performance over a fully distributed architecture.
Clustered RAN
A RAN architecture where base stations are centralized in a “hotel,” which may be a fiber center. Operators in South Korea and Japan rely on this architecture for operating expense reduction while other operators implement it selectively to overcome operational challenges such as lack of space or security at the cell site.
Coordinated RAN
We’ve heard this term from people that focus on features such as CoMP and enhanced Inter-cell interference coordination. Centralization of the baseband processors reduces latency in the connection between two base stations so they can coordinate better.
Clean RAN
Here’s another variation on “CRAN,” which simply means that a centralized baseband pool can run more efficiently. Don’t take this one too seriously.
Centralization and virtualization of the RAN will accelerate with the advent of “5G” technologies, which will rely heavily on heterogeneous networks to meet performance targets. The hybrid RAN architectures will gain traction as networks migrate to LTE-Advanced Pro and ultimately to 5G. In the meantime, the domain for VRAN will start by addressing local-area deployments to serve venues and congested neighborhoods where the benefits most heavily outweigh the cost of virtualization.
Recently, research and development projects have proven the technical feasibility of virtualization, opening up a window for operators to achieve significant savings in capital expense and opex. In a recent Mobile Experts survey, most operators worldwide have now decided on how they’ll utilize centralization and virtualization on LTE networks, and how CRAN and VRAN will play a role in migration to 5G. The future is bright for flexibility in the network.
Joe Madden is principal analyst at Mobile Experts. Madden provides most of the business analysis behind our forecasts, as well as primary research in semiconductor areas. Over 26 years in mobile communications, he accurately predicted the rise of digital predistortion, remote radio heads, small cells, and the mobile IT market. He validates ideas with mobile and cable operators, as well as hardware suppliers to find the match between business models and technology. Madden holds a Physics degree from UCLA. Despite learning about economics at Stanford, he still obeys the laws of physics.
Frank Rayal completed his undergraduate degree at Case Western Reserve University, majoring in Electrical Engineering. He later acquired his MASC and MBA at the University of Toronto in Canada. Rayal has previously worked with Ericsson, Metawave, Telesystem Innovations, Redline Communications and BLiNQ Networks. Rayal is a Senior Analyst for Mobile Experts, specializing in Cloud RAN and IoT systems analysis, and a partner at Xona Partners and has been collaborating with Mobile Experts since 2012. He is based in Ottawa, Canada.
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