Building Efficient Disaggregated Fronthaul Networks

The first 5G networks were rolled out in 2018. The 5G journey is a marathon and not a sprint. 3GPP has a schedule of 6 to 7 years and five 3GPP releases for different parts of the technology to be ready for deployment. By 2024, 5G will have 10% of global connections. Conversely, this means that there will be a significant amount of 4G still around. 4G is expected to coexist with 5G well into the 2030s in mobile networks. Of course, the percentage mix will vary with geography; for example, China and North America will have significantly more 5G connections than 4G while Africa and India will have substantially more 4G connections than 5G.

As operators migrate their infrastructure to enable 5G services, studies indicate that 70% of the network investments will be in the RAN (Radio Access Network). An efficient infrastructure backbone utilizing the large capacities laid out is necessary for telco market players to achieve optimal TCO (Total Cost of Ownership) and make the RAN investments viable. This points to the following basic needs:

  • Converged solutions that can handle the mix of 4G and 5G deployments
  • Reusable hardware platforms that can be deployed in different scenarios, which is possible only through disaggregation of hardware and software functions
  • Virtualization of RAN functions to optimize hardware and real estate resource usage
  • Flexibility to choose inter-operable products from different vendors to optimize time and cost which is possible only through open networking enabled by the Open RAN

The new challenge now is to design modular, flexible, programmable and reusable platforms that can address the diverse network scenarios for bandwidth, latency and cost, while being truly open and completely interoperable.

The switching process and traffic aggregation at gateways create varied latency to the switched packets. However, there are constraints to the maximum latency between the radio head and the baseband. So, fronthaul networks must be able to constrain the delay and must guarantee low latencies and minimal jitter to sensitive signals. The IEEE P802.1CM provides specifications for time sensitive networking in the Fronthaul to enable the transport of latency and jitter constrained Fronthaul streams in a bridged Ethernet network. The IEEE P802.1CM collects the various requirements and information flows required for the efficient working of the fronthaul and provides guidance to meet these requirements and incorporate these features in the building of these networks.

The need to address the co-existence of both 4G and 5G networks in the years to come creates the necessity to have an open and adaptable fronthaul network. Different scenarios of traffic split (Option 8, Option 7, Option 7.2, Low-PHY, etc.) must be addressed so that the network element can be deployed/reused in different situations. This is the only way to minimize expensive hardware wastage. Today, this is not possible with fixed functions ASICs and the only way is to bring in programmability into the network elements by using components such as FPGAs to complement high throughput ASICs. The combination of the right components provides the optimal mix of cost, capacity, speed and reliability.

Unlike yesteryears, today, no single supplier can match the speed of innovation required by operators. This creates the need to handle a multi-vendor network, which is possible only with open and interoperable hardware and software components. The O-RAN (Open RAN) initiative facilitates alliances between the various software and hardware solutions to build interoperable and open components that can work together. O-RAN allows for the interaction between various devices or combinations of these fronthaul elements to help innovate and achieve more cost effective and transparent solutions. Software-Defined Networking (SDN) and Network Function Virtualization (NFV) are being tested to obtain an optimal cost in the fronthaul part of the RAN. An O-RAN Intelligent Controller (RIC) provides control over the various functionalities which results in a more efficient and better managed network. The combination of SDN and NFV is crucial to achieving optimization, efficient arrangement and control the RAN interface.

Fronthaul networks are viewed strategically to have the ability to support multiple generations of wireless communication devices. The interface supports the use of real time 5G networks for mobile devices and applications and also can be used as edge routers for MPLS (multiprotocol label switching) VPNs (Virtual Private Networks) to serve enterprises and help the network operator to generate more revenues. This requires the platform, especially the software, to be modular to address very simple fronthaul transport scenarios to complex combinations of traffic mix.

Capgemini Engineering software framework, widely deployed in carrier networks around the world, now enables disaggregated solutions for fronthaul switches and gateways. This includes:

  • Flexible and programmable network functions leveraging ASICs for performance and FPGAs for flexibility
  • CPRI – Ethernet interworking
  • RoE (Radio Over Ethernet)
  • Transport of CPRI and eCPRI over Ethernet networks
  • Timing and synchronization
  • IEEE 802.1CM Time Sensitive Networking
  • Yang models and full Netconf manageability

Capgemini Engineering’s partnership with UfiSpace makes the software available on a white box platform such as the UfiSpace. This offers the full benefits of disaggregation in architecture, design and engineering while simultaneously delivering the advantages of hardware and software that will seamlessly work together out of the box.

This model provides the shortest time to market as well as the most optimal cost to improve return on investment in the fronthaul network, thus creating the best chance to succeed in this fast-paced, evolving market. This is further complemented by Capgemini Engineering engineering services with extensive experience in both wired transport and wireless communication domains, significantly reducing the uncertainty and time to launch products. Read more about Capgemini Engineering’s fronthaul switch software framework.


Rajesh Kumar Sundararajan

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