Foreword

4G LTE was about broad-reaching, universal connectivity and coverage. However, 5G is about an immersive experience, led by new services-enhanced mobile broadband access everywhere, massive Internet of Things (IoT), tactile Internet, higher user mobility, ultra-reliable communications, and enterprise use cases. These services have divergent latency, scale, and throughput requirements requiring network transformation in addition to 5G New Radio (NR) evolution. However, 5G is not just about radio; it is genuinely a network and services evolution. The promise of 5G services looks to be simultaneously an evolutionary and revolutionary opportunity.

The opportunity comes from new applications, business models, innovative new revenue streams, and leaner operational efficiency for mobile operators—all directly contributing to a more profitable set of offerings and robust business. However, the evolution of the mobile operator’s network is a significant financial (current ARPU being flat or declining) and engineering undertaking that must be thought through from end to end. The new network infrastructure must simultaneously satisfy 2G/3G/4G requirements and 5G’s exploding bandwidth demands, massive logical scale, and the incredibly low-latency needs of new applications and services in an efficient, automated, programmable manner.

The traditional network design will not address these divergent 5G service requirements since services need to be placed closer to the edge to deliver ultra-low latency. Massively scalable, low-latency–enabled applications at the edge will open up new ecosystems and business models across every industry’s enterprise and residential markets. Hence, programmable network fabric, packet core evolution to Control Plane and User Plane Separation (CUPS), Multi-access Edge Computing (MEC), and network slicing will be the critical enablers for 5G architecture.

Mobile network operators have built large-scale LTE/LTE-Advanced networks that are mostly centralized today. Now they need to evolve their networks to accommodate 5G requirements. However, 5G is not only about mobile operators. Alternate access vendors (AAV) will also need to evolve their network and services to cater to 5G service delivery needs. Enterprises will deploy private 5G.

Along with the significant technological change to the mobile core and radio access network (RAN), operators will also need to evolve their transport networks to cost-effectively deliver a satisfying mobile broadband experience while simultaneously meeting the scale requirements for massive IoT and the ultra-low-latency requirements for real-time applications. With the evolution of Centralized RAN to Cloud RAN, RAN decomposition (that is, the breaking down of baseband unit to virtualized centralized unit (CU) and distributed unit (DU)), virtual packet core to CUPS, and new services, IP transport will need to enable seamless connectivity and reachability, and support the flexible placement of mobile functions. 5G will also help the convergence of wireline and wireless architectures to support a broad range of SLAs for service and transport, starting with the stringent latency, bandwidth, and timing requirements. RAN densification (sub-6 GHz and mmW) in 5G, either by adding a new spectrum or by adding antennas, sectors, and/or carriers in the existing sites, will result in a massive number of service endpoints. The only way to avoid operational complexity is to reduce touchpoints for service enablement.

All that being said, we need to manage the financial impact in 5G, meaning we need to reduce CapEx/OpEx. The only way to achieve that would be stat-muxing using IP/Ethernet to reduce access costs instead of TDM technology.

It is therefore critical to invest in a 5G transport network that will underpin the worldwide adoption of 5G technologies and delivery of applications.

I had the opportunity to work with network operators globally to help them in their 5G transformation journey. Most of them had similar questions: Will their network accommodate 5G network requirements of increased bandwidth, large scale, and low latency? How would they address the placement of the 5G cloud-native RAN network functions centralized unit (CU) and distributed unit (DU) and the packet core’s control and user plane functions? Is O-RAN ready for their deployment use case? Do they need to upgrade their cell site routers as well as pre-aggregation and aggregation routers for their existing and new C-band and mmW spectrum? How will they address low-latency edge use cases? What will be the requirements for the new far-edge, edge, and regional data centers? Can they place the user-plane function on the public cloud? How will they place compute at cell sites? What are the benefits of Cloud RAN, and what percentage of their RAN architecture will be fronthaul, midhaul, or backhaul? How can they deliver packet-based fronthaul? What are their dark fiber requirements? How can they monetize their network architecture to provide enterprise services? What are the network slicing requirements? How can they be ready for 5G and beyond? What is private 5G?

Besides network evolution questions, 5G network also requires changes in the network operator’s organizational structure due to a lack of clear responsibility demarcation. It involves transport, mobile core, virtualization, and RAN teams to understand the requirement of their adjacent areas.

A Network Architect’s Guide to 5G takes a holistic approach of providing an end-to-end mobile network evolution overview, starting with legacy 2G/3G and 4G LTE network architectures. It then introduces the promise of 5G with 5G fundamentals, followed by an in-depth coverage of 5G network transport, data center, edge data center, clocking, and 5G network design. It has done a great job of addressing the preceding questions and concerns by the network operators.

It may be the first book covering the mobile core, transport, RAN technology fundamentals, and network design details. I would highly recommend this book for anyone who is already working on 5G transformation or is in the planning phase or for anyone who wants to understand end-to-end 5G network technologies and design.

—Waris Sagheer
Chief Technology Officer,
Service Provider, Cisco Systems