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Cloud RAN and MEC: A Perfect Pairing
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CRAN and MEC: benefits of co-deployment
Edge presence is viewed as absolutely necessary to enable certain use case classes defined for 5G. The 5G
use cases have been classified into three service types (see, e.g. [1]): eMBB (enhanced Mobile Broad
Band), URLLC (Ultra Reliability and Low latency Communications), and mMTC (massive Machine Type
Communications). In particular, the URLLC service type includes use cases related to Tactile Internet,
Interactive Gaming, Virtual Reality, automotive, industry and automation. A common characteristic of
these use cases is the need for low end-to-end latency. Physical limitations (i.e., speed of light) prohibit
execution of these use cases in the traditional “deep” or “remote” cloud. The eMBB service type
encompasses another kind of challenge - a previously unseen volume of upstream data associated with,
for example, high-definition video sharing. Finally, the mMTC set of use cases covers applications where a
large number of IoT devices, such as sensors, are sending data upstream, collectively creating a significant
data volume passing through the network. Moreover, this data is highly localized and is often associated
with a requirement (due to privacy, data ownership, etc.) that it shall not cross certain domain
boundaries. It can, therefore, be concluded that the 5G use cases all call for some processing of data
and/or proximity at the edge of the Radio Access Network (RAN).
From a Mobile Network Operator’s (MNO) point of view, a major challenge in enabling applications
associated with the 5G use cases is the significant investment required to deploy a sufficiently extensive
network of edge computing Points-of-Presence (PoPs), so that it becomes attractive to develop
applications exploiting the edge processing infrastructure in mind. Moreover, this investment must be
made in advance of applications being ready to take advantage of it – i.e., this is an investment in
anticipation of future revenue, but without any guaranteed near-term returns. One way to mitigate the
significant cost (and risk) of such strategic investment is to bootstrap a Multi-Access Edge Computing
(MEC) deployment to the deployment of a Cloud RAN (CRAN): the cost of providing additional processing
power across an already planned pool of centralized processing points (e.g., a pool of Base Band Units
(BBUs)), should be significantly lower than a standalone MEC deployment.
Conversely, deployment of a CRAN across generic computing infrastructure (as opposed to dedicated,
RAN-optimized hardware) is itself a significant investment for an MNO. In addition to the costs of
deploying CRAN processing units themselves, there is the cost of moving towards virtualized RAN
appliances, testing, integration and maintenance of these new solutions. While the operational flexibility
and network re-configurability offered by virtualization may carry significant long-term benefits, the near-
term effort and costs can make it a tough pill to swallow. The significant strategic benefits of MEC can
make the decision a much clearer one.
Among the investments in mobile network infrastructure, the RAN represents the major part of the
MNO’s Capital Expenditure (CAPEX) - this is in addition to the cost of the spectrum itself, while
maintenance, possible use of leased transport network lines and network optimization add significant
additional Operational Expenditure (OPEX). Given this situation, a CRAN deployment which virtualizes
much of the RAN functionalities on standard General-Purpose Processors (GPPs), is seen as an important
technology enabler for reducing the Total Cost of Ownership (TCO), associated with the RAN. The amount
of investment and the Operation and Maintenance (OAM) costs are expected to decrease fast thanks to
maturing cloud technologies and deployment experience. The CRAN approach facilitates a faster radio
deployment, drastically reducing the time needed in conventional deployments. There are evident CAPEX
and OPEX benefits derived from a more efficient site management (less rented space and energy, easier
negotiation with owners, etc.), energy savings, network simplicity (for current and advanced