After years of hype about gigabit speeds that will let consumers download full-length movies in mere seconds, 5G is close to becoming a reality. Last year gave the industry a taste of 5G as Verizon launched a home broadband service using the next-gen wireless technology and AT&T brought 5G service to a dozen cities. The 5G ramp up has continued across the globe throughout 2019, with initial services starting to be rolled out in many countries, bringing lots of media coverage about the 5G-enabled future.
However, the industry risks a touch of buyers’ remorse if we aren’t clear to end-customers on how 5G will evolve over the next few years and when the new 5G services that offer real differentiation to 4G services beyond faster connections will appear. To be fair many network operators are articulating their service evolution plans to customers but the mainstream media, especially television reporting, seems highly focused on the initial high-speed broadband services which risks quickly turning to disillusionment if the expectation of new alternative 5G services doesn’t meet reality. The promise of 5G continues to be enticing with the Internet of Things (IoT), connected and self-driving cars, and a laundry list of innovations for augmented and virtual reality. These advanced services will come in the not too distant future, but what must we do to prepare mobile networks to support them?
Within the industry we need to continue to be clear on the phased introduction of 5G and the impact of this on the network infrastructure needed to roll out 5G. Much obviously needs to be done within the 5G core and RAN as 5G evolves, but mobile transport networks will also need to step up performance to meet the demanding requirements of 5G including bandwidth, synchronization, and lower latency. All these requirements of mobile transport will be significantly higher on 5G than a 4G network and bring substantial challenges to the underlying mobile transport network. The 5G-ready mobile transport network is far more than just the collection of dumb pipes, albeit high-performance dumb pipes, that were required for 4G. Innovation is taking place at a rapid pace within the transport network today and Mobile Network Operators (MNOs) and wholesale operators need to address evolving transport network requirements to deliver on the promise of 5G.
The first aspect we should consider for 5G evolution is the timeline for services and the impact these have on the underlying transport network. Compared to previous 4G data-based services 5G explodes the mobile world into a potentially vast array of differing service types and business models, which are displayed graphically in the following figure created by the ITU-R:
Figure 1: The International Telecommunications Union, Radiocommunication Sector (ITU-R)’s vision of the future international mobile telecommunications (IMT) services. Source: ITU-T
Initial 5G standards, the so called non-standalone (NSA) variant of the 5G specifications, enable MNOs to start rolling out 5G enhanced mobile broadband (eMBB) services that utilize new 5G radio capabilities but maintain the current 4G core. Essentially these services are souped-up 4G services providing higher speed data services, generally known as “5G phase 1”. MNOs across the globe are in the early stages of rolling out these initial 5G phase 1 services with higher speeds than previous 4G services but with underlying service specifications and business models that are largely the same as 4G services.
The next step for 5G is the expansion of the work within the standards bodies to bring the initial standardization of full 5G capabilities, in phase 2. Within the 3rd Generation Partnership Project (3GPP), the predominant standards body for mobile standards, this forms the bulk of the Release 16 specification which is currently underway and due to be completed in March 2020. This will enable system vendors, and ultimately MNOs, to build systems and then networks that support the broader range of 5G services and business models. Standardization work is an ongoing process and 5G specifications will continue to evolve for many years as technology, networking functionality continues to evolve and mature, enabling ever more advanced 5G services and business models.
Opening up 5G with Phase 2
The key advance with the second phase of 5G is that mobile networks will open up to a significant broadening of services beyond voice and highspeed data, as shown in Figure 1. Massive machine type communications will broaden the capabilities of mobile networks to address massive IoT applications with up to tens of thousands of connected devices per cell. Ultra-reliable low-latency communications brings a drop in round-trip service latency from 10 milliseconds to just 1 ms opening up 5G networks to a whole range of new applications.
The exact new services and timescales they will be available is still largely uncertain although many MNOs have publicized broad timelines with initial 5G phase 1 services entering the market in 2019-2020 and initial phase 2 services from 2022-2023 onwards.
The impact of 5G on network operators
The initial rollout of 5G phase 1 services largely impacts the radio aspects of the mobile network with investments largely targeting new 5G cell sites with more modest investments in the backhaul transport network and back-office IT systems. However, the introduction of 5G phase 2 services brings the potential for radical changes in the interaction between MNOs and customers as service portfolios expand to embrace the full potential of 5G. Phase 2 capable transport networks will be required before the first phase 2 services go live.
The introduction of lower latency services and other more advanced networking functionality will expand MNO activity beyond the radio to the new 5G core, the underlying optical networking-based transport network and the back-office management and control systems. As new 5G millimetrewave radios have a shorter reach than 4G radios, one of the largest changes that phase 2 will bring is the proliferation of 5G cells and where possible fiber deep x-haul for transport. As MNOs move to phase 2, many of those that don’t already use mobile fronthaul for 4G will migrate to a cloud-RAN architecture that introduces a fronthaul segment of the network between the Radio Unit (RU) at the cell site and the Distributed Unit (DU) at a local aggregation point in the network. 5G fronthaul brings considerable performance challenges with very low latency requirements limiting fronthaul to around 15 kilometers and tougher synchronization requirements dropping to as low as 65 nanoseconds or lower. X-haul networks will need to support 4G and 5G fronthaul, midhaul and backhaul traffic flows over a common transport network.
Figure 2: 5G Architectural Change for Radio and Transport. Source: Infinera
To address challenges such as reducing other overall round trip latency, then new capabilities such as multi-access edge compute (MEC) will be introduced that will bring storage and compute functions at new locations between the cell tower and the core that can be used to support services for the business community. Furthermore, to address the varying transport performance requirements for new services MNOs will introduce new network slicing technology to nail up bandwidth and MEC resources within the transport to support specific service classes. All of this requires sophisticated software defined networking (SDN)-based network orchestration and machine-learning capabilities that will automate many aspects of dynamic network control.
In summary, to get the new phase 2 game-changing 5G services that customers are expecting, MNOs and wholesalers will need to radically change mobile transport networks to meet the scalability and performance requirements for individual service types. All this needs to be done before phase 2 services are introduced meaning we’ll see significant changes in mobile transport as MNOs get ready for phase 2 and those new services that customers are eagerly awaiting.
