Neutral hosts that provide shared infrastructure to many service providers will be essential to the at-scale deployment of small cells in many scenarios. Economic analysis and early case studies show that shared infra can dramatically improve a network’s cost and ROI, and may be the only way to extend cellular coverage to many areas in a viable way.
Shared infrastructure reduces total cost of ownership for operators and replaces CapEx spikes with predictable OpEx fees and shared risk. For user organizations, the footprint of the network is reduced if there is just one set of infrastructure, plus interference can be avoided, and energy consumption minimized.
However, the model is immature in the small cell world and there are many different approaches, which could threaten the economies of scale that infrastructure economics require. Each deployment will have its own requirements in terms of density, coverage, performance and use cases, which will be best served by different architectures, from DAS to emerging small cell virtualized RAN. However, using a mixture of sharing models and architectures can compromise the neutral host’s business case by creating fragmentation and complexity, and that can be exacerbated by the development of regionally specific approaches.
Last September, Small Cell Forum made an important step to address the challenge of encouraging diversity, while avoiding fragmentation. It proposed a common framework for neutral host deployments, called Hosted RAN and outlined the requirements in paper called Neutral Hosting Architectures (SCF244).
Now, just nine months later, SCF has defined requirements for each of the shared infra architectures and applied them to different categories of network tenants such as MNOs, MVNOs and private network operators. The paper, SCF245 Neutral Host Requirements Part 2: Hosted RAN high-level design, sets out a detailed common design framework within which neutral hosts and service providers can plan their deployments, confident that these are based on a common set of foundations and customer requirements.
Neutral hosting is not a one-size-fits-all model, nor does SCF suggest it should be. Instead, it proposes common architectural and commercial foundations on which many deployers can innovate with confidence.
Key elements of the design framework include unified approaches, based on stakeholder requirements, to network management and operations support; security; spectrum; cloud infrastructure; radio/antenna capabilities; transport; synchronization; network resilience; and capacity provisioning.
SCF is always clear that it does not aim to reinvent the wheel and is keen to build its frameworks and blueprints on existing, proven work if that is possible. The Hosted RAN design is a good example, since it builds on an internationally recognized UK initiative called Joint Operator Technical Specification for Neutral Host In-Building (JOTS NHIB), which was agreed by the UK’s MNOs and sets out technical requirements for shared in-building networks.
This has been a valuable cornerstone for Hosted RAN, providing tested approaches not just to technical specifications but the commercial issues around operator cooperation and multi-tenancy. SCF now takes JOTS NHIB and seeks to expand its impact dramatically, both by making it globally applicable, and by extending it to non-MNO tenants of neutral host networks, such as private network operators, MVNOs, venues, and enterprises that want to deploy and manage small cells directly.
An important element of the ongoing work is that all neutral host stakeholders are represented, so the resulting frameworks really will address all aspects of the complex neutral host value chain. The SCF work was led by several member companies, representing a cross-section of Hosted RAN stakeholders including neutral hosts and operators – the leaders were BT, Cellnex, CommScope, Crown Castle, Dense Air, Freshwave and Reliance Jio. The co-leaders of the project come from very different neutral host players – Mike Ferris, chief network architect at DenseAir, which has pioneered an innovative approach to neutral host small cell deployments in different types of spectrum; and George Aguilera, technology strategy at Crown Castle, one of the USA’s biggest TowerCos.
The next steps will be to define a structural framework for neutral host business models at a detailed level and to carry out further work on some of the key requirements identified in this document. These critical components of future shared networks include open interoperability; network slicing; KPI sharing with tenants; reporting and analysis; blockchain and content security and quantum computing.
This ongoing work will result in a series of documents and tools that should lower many of the current barriers to at-scale neutral host deployments and play a highly significant role in accelerating small cell roll-out, with high socio-economic impact for enterprises, communities and cities.