Telecoms.com periodically invites expert third parties to share their views on the industry’s most pressing issues. In this pieceLi-Ke Huang, VP of Wireless Technology, Wireless Business Unit at Viave Solutions, argues mobile operators must develop a robust 5G roadmap that leverages their existing network assets.

There is no universal approach to 5G development, as different markets face different circumstances which require different approaches. In the US, for example, operators such as Verizon are focussing on delivering 5G connectivity using point-to-point fixed wireless technology. Meanwhile, operators in other countries, including China and Japan, are focussing on developing 5G in line with the 3GPP new radio (NR) specification for the enhanced Mobile BroadBand (eMBB).

However, regardless of the technology they use to deploy 5G, operators must set a clear roadmap that has the requirements of the end-user/industry in mind, but also aligns with the timescales and expectations of the regions they’re operating in.

Operators will be looking for large portions of new spectrum to deliver 5G. Ideally, 100MHz of bandwidth should be assigned to each operator in order to support the high data rates needed for 4K streaming and other high-bandwidth services. Yet, in the UK spectrum auctions which took place earlier this year, service providers were only able to gain 50MHz of new spectrum, limiting their capabilities and potentially leaving the UK languishing behind other countries.

In order to be granted the necessary amount of spectrum from regulators and the government in the next auctions scheduled for 2019, operators need to demonstrate, together with vendors, that they can solve existing problems in today’s LTE and 3G mobile networks by developing new 5G networks.

This is crucial, because for five years or so, the majority of mobile coverage will continue to be provided by LTE. Consequently, operators are now enhancing the life-span of their LTE networks, introducing new air interface functions and capabilities within the 3GPP LTE technology framework, to support low-latency IoT applications and high-bandwidth data services.

And so, as operators move towards a 5G future, they must first improve their LTE networks and make them 5G-ready in good time for the commercial roll-out of the next-gen standard.

LTE and 5G interoperability

5G will coexist with 4G technology (old versions of LTE and new versions such as LTE-A), as well as 3G and even 2G in some regions. 5G new radio (NR) equipment can be attached to existing mobile radio access network (RAN) infrastructure, without the need to completely upgrade existing wireless networks. Once 5G technology is proven to work alongside today’s networks, wide-scale deployments will commence.

According to the 3GPP release 15 standard for 5G, the first wave of 5G networks will be non-standalone (NSA), meaning that 5G will be supported by existing 4G infrastructure. Splitting RAN functions means 5G devices will connect to 5G radios for data throughput but will still use 4G for non-data duties.

This integration allows operators to maximise their existing 4G investments and cost-effectively move towards 5G as well as ensuring there is only one system to maintain in the future. Business justifications such as this should help in the argument for greater allocation of spectrum from Ofcom and the government.

Transitioning to 5G

Operators are considering a number of architectural changes to their networks in preparation for 5G. One major focus for operators is virtualising 4G base stations – otherwise known as vRAN. The vRAN approach replaces base band units with commercial off-the-shelf technology and virtualised software, hosted in a flexible, data centre environment. With less proprietary hardware and lower energy consumption, this approach offers a cost- and energy-efficient RAN architecture, which can support current 3G and 4G standards, whilst being easily upgradable to support 5G.

Operators are also beginning to experiment with split RAN. There is a need to split the functionality of the network into different layers of the 5G protocol and into different logical, physical or virtual entities. The split architecture results in the necessary scaling dimensions to support 5G use cases and traffic structures in a cost-efficient way. It also guarantees that RAN architecture is future-proof. As an evolution of 4G RAN, the split can be gradually introduced in line with business needs.

By combining networking slicing and split RAN designs, the programmable 5G network architecture will give mobile operators the most control and flexibility over their network infrastructures. This will ensure the service quality, maximising the resource utilisation thus increasing the return on investment on their network equipment, transport networks and licence fee of the spectrums.

Mobile Edge Computing (MEC) – where network processing functions are moved closer to the end-user – is also gaining recognition as one of the key enabling technologies for 5G. It will be particularly important for critical low-latency applications such as connected cars and virtual healthcare, as well as for speeding up data-hungry services such as video streaming and packet brokering. Just as the push for all IP networking was a 4G milestone, locating intelligence at the network edge will be a 5G milestone. Enabling services and content to be activated closer to the subscriber is key to next generation mobile networks.

Testing LTE and 5G specifications

As operators develop their LTE and 5G networks, comprehensive testing of their RAN, core and mobile edge infrastructures is required. Operators must be able to simulate a huge range of end-user and IoT devices, modelling real world conditions.

Operators must validate the full range of new 5G features, including Massive Multiple-Input, Multiple-Output (MIMO) beamforming technology, and ultra-reliability, low latency use cases, which require a virtualised lab environment to be tested effectively. They also need to test network performance in new frequency bands in both the mmWave and sub-6GHz spectrum. It is vital that operators continue testing the performance and security of their networks before they are used in a commercial setting.

For the UK to continue to thrive as a technology powerhouse and take a market lead in commercial 5G, operators need enough spectrum to facilitate all possible exciting 5G use cases. However, justifying the same amount of spectrum as has bee allocated in other countries means meeting the challenges of the UK market and solving existing network issues through an integrated approach. We are well on the road to a 5G future, but that road is paved with 4G architecture and stringently tested networks.

Dr Li-Ke Huang is the VP of Wireless Technology at Viavi Solutions (Wireless Business Unit) leading the Technology Group and the Algorithms Group and is responsible for product concept and core technology innovations contributing to the company’s technological and business visions, directions and strategies. Li-Ke specialises in leading multiple early technology research programs for the Test Mobile product family, which has been the de facto global standard for 2G, 3G, LTE, 4G and 5G wireless network technology prototyping and testing and acquired extensive knowledge wireless technology R&D and business development cycles.