FEATURE
access the cloud using clusters of LTE base stations. Uplink signals from multiple base stations optimise network configuration by selecting the best signals at a number of receivers, thus minimising the effect of interference from other operators. Virtual networks for different user groups are capable of being created, by the concept of ‘network slicing’, to enable a degree of separation within the cloud. Small cells are envisaged, which not only means much-improved radio connectivity within buildings but would allow end user devices to connect directly with each other. This aligns with the concept of ‘mobile edge computing’ that pushes the core functionality out to cell sites. User equipment would typically connect to multiple cells. All of this requires radio spectrum, meaning that everhigher frequencies are needed to fulfil the need - typically between 20 and 60GHz will be allocated. 5G technology development is substantially completed (up to release 15 on the standardisation programme with release 17 seen as the effective end point) and has reached the point whereby equipment will shortly be produced commercially.
A mobile operator’s view The BT/EE view, as put forward by Philip Bridge who has responsibility for network architecture, shares the vision for what 5G is capable of offering but has significant doubts as to how this will be realised. A new core will be needed to achieve the benefits of infrastructure decoupling, virtualisation within the cloud and the introduction of new services. 5G is being considered in three different ways; a ‘Network View’ a ‘Functional View’ and a ‘Deployment View’. How to integrate these three perspectives is potentially very difficult. Currently, a silo mentality prevails in the supplier community, thus making development of a ‘common cloud’ something of an alien culture. There will also be a need to integrate 5G with the ‘long tail’ of legacy equipment in 2G, 3G and 4G networks and provide roaming between all of them. The need for interworking boxes may have to be considered although this is not a desirable way forward. 4G networks are already being built on a 5G basis, thus making the eventual solution easier. Even if established, the instrumentation and training required to achieve excellent network performance is not easy with a cloud-based architecture. Methods used today for network
monitoring will not work for the 5G vision and thus a transition has to happen, but with no means of knowing how this can be achieved. It is considered that very few vendors have the stature to build a network of this type and a multi-vendor solution may have to be forced by some form of legislation. Infrastructure sharing is a likely way forward with ‘Telco Grade’ networks setting the required standard. A combined service orchestration to break up the silos with a simpler but more stable architecture will need putting in place. The goal is full interoperability between vendors A, B and C in both hardware and software, which will be difficult to mandate and manage in terms of who would be in control of exactly what. If not executed properly,
Rail Engineer | Issue 163 | May 2018
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