Centralized basebands connected via fronthaul to remote radios supports network densification
Small cells are a fundamental driver of the ongoing network densification that is enhancing LTE networks and building a foundation for 5G. As demand for mobile data and the number of devices continues to grow, small cells will be essential in delivering the capacity and coverage consumers and businesses demand. And with new small cell deployment models gaining traction, let’s examine the role fronthaul will play in ultra-dense 5G networks.
Backhaul is a widely known term that describes the link between a baseband and the core network. Fronthaul, on the other hand, connects the baseband to a remote radio unit. As it relates to small cells, operators are increasingly centralizing baseband resources and using fronthaul to connect a cluster of radios. This can simplify deployment by decreasing equipment footprint and improve network efficiency by allowing for centralized management of resources.
What does this look like in the real world? Orange Poland is continuing with its 5G strategy most recently by working with network infrastructure vendor Nokia to test out a cloud-based radio access network. The cloud RAN trial, which ran from March to May, saw radio sites fed by a virtualized baseband deployed in a data center 70 kilometers away; Ethernet fronthaul served as the transport mechanism.
This project represents a further evolution of centralizing basebands; once equipment is colocated, then it can be virtualized. Instead of a proprietary box, baseband functions run as virtualized network functions on commercial-off-the-shelf server hardware.
One key part of transport for 5G is significant increases in capacity. With promised user data rates in excess of 1 Gbps, there’s the need for bigger pipes.
Analyst Jason Marcheck of Layne Bridge and Associates noted that discussion of the radio access and core networks sometimes overshadows discussion of the transport network. “As operators prepare to deploy 5G in a meaningful way, they are finding the need to fundamentally rethink their mobile 5G transport strategies. As opposed to previous generations of mobile transport development 5G will add several new vectors of complexity that were not front and center issues as mobile networks developed from 2G to 3G to 4G/LTE. It would be easy enough to point to IoT as a leading driver in the increase in complexity, but the true reason(s) are both more fundamental and complex. The heart of the issue is that since 5G is more than a new mobile network generation, the diversity of applications a true 5G network must support go well beyond mobile…As more applications begin to leverage a 5G network, as opposed to just a fixed network, or just a mobile network, or just an enterprise network, the number of applications that will compete for resources will increase dramatically.”