As 5G networks start to build out, they bring new requirements for the evolving RAN, and, specifically, for fronthaul networks that connect the baseband and radio elements in the macro base station. With 5G expected to expand the capacity of the mobile network by a factor of 10 or more, while simultaneously tightening key synchronization requirements by a factor of two or more, existing Ethernet fronthaul methods simply aren’t up to the task. Broadcom is tackling this issue with a purpose-built Ethernet switch that leverages a recently gelled IEEE specification.
The Common Public Radio Interface (CPRI), the semiproprietary interface protocol used for most all 4G fronthaul, is the de facto standard for fronthaul today. But CPRI offers mainly point-to-point transport and requires precise time synchronization, a configuration that can’t support nondeterministic packetized networks, or the centralized and virtualized RAN architectures that will be the basis of 5G. Cloud RAN, massive MIMO, LTE Advanced carrier aggregation and more simply outstrip CPRI’s capabilities. Further, it is unable to support the convergence of macro-, micro-, pico- and small cells via bridging.
"5G will drive an order of magnitude increase in network-bandwidth requirements owing to faster radios and denser networks coupled with larger base stations serving more radios,” said Bob Wheeler, principal analyst at The Linley Group, in a release. “As a result, the industry is moving away from point-to-point CPRI radio links and towards a switched Ethernet infrastructure based on new protocols like eCPRI and IEEE 1914. Broadcom has developed a unique solution by extending its terabit Ethernet switch to address this new radio fronthaul application by adding support for Ethernet-based 5G radios as well as installed CPRI-based LTE radios."
The Monterey switch (BCM56670), built on Broadcom’s terabit-class switching platform, was created specifically for that scenario and the 5G use case in general (including building mobile-edge computing platforms). It’s based on the IEEE’s 802.1CM Time-Sensitive Networking for Fronthaul standard, which defines high-resolution, high-accuracy synchronization, CPRI radio-to-Ethernet bridging, and nanosecond-scale jitter and delay control, and has been engineered to meet the bandwidth, flexibility and strict synchronization and jitter requirements of the next generation of mobile networks.
Critically, Monterey supports next-gen 5G radios along with existing CPRI-based radios, so operators can consolidate hybrid radio traffic onto a standard, Ethernet-based infrastructure; and it shares a set of common API interfaces with other Broadcom switching products via the Broadcom Software Development Kit.