5G vs 5G: Network Slices or Private Networks? Featured

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5G vs 5G: Network Slices or Private Networks? Image Credit: Siberian Art/Bigstockphoto.com

Here’s your bedtime history anecdote. Once upon a time (around 9th century BC) there lived a King called Shalmaneser in the Kingdom of Assyria, now northern Iraq. The king was worried. He had a hard time keeping his kingdom together and maintaining good relations with his neighbours. But in the course of time, he realised that the best way to achieve this was to build a network to remain closely connected with his governors and his ambassadors in other kingdoms. So he built a fast, reliable and secure imperial communication system, known as the ‘King’s Road’. How did he achieve all the KPIs? Well, in several ways. First, he made a private network of roads only to be used by his officials. Second, he made road stations in different parts of his kingdom. They acted as regional hubs for the exchange of information, relay of letters to the next courier agent and even for holding official meetings. Without these stations, information had to travel back to the center of the Kingdom, and this would have required more time and resources. The benefits of edge computing over centralised computing and local data offload over traffic backhaul were perhaps realised in those days. A traveller always used 2 mules, just like we have redundant communication platforms and networks nowadays. To achieve secure communications, official documents were stamped and sealed.

Fast, reliable and secure: these were the principles behind Shalmaneser’s network. In the era of 5G communications these attributes seem to have immense significance. The questions are: How fast? How reliable? How secure? It all depends on how you see them.

The manufacturing, aerospace and automotive industries generally exchange machine type data based on deterministic communication framework. For realising that, most of them bet on Time Sensitive Networks (TSN). TSN based on IEEE 802.1Q Ethernet was conceived as a layer 2 protocol where the amount of time taken for the information to travel from point A to point B could be predetermined. So it is imperative that for a TSN network, predictability and reliability are the crucial parameters. This is achievable in a fairly straightforward manner as long as the communicating nodes, say in a factory environment, are stationary. You design the network with the right topology and protocol that fits in the factory ecosystem. But when the collaborating nodes are mobile in nature, those simple choices cannot be made anymore. Practically, in a factory environment, channel impairment is a predominant issue, because of the impediments caused by metallic structures and manufacturing equipments. Signal penetration related problems can be tricky. Data channels established with end nodes can make and break unremittingly, disrupting mission critical communications. Wifi as an access technology is not a preferred option as it can only support mobility in a limited way. So mobile network based solutions supporting low power technologies like NB-IOT and LTE-M proved to be better choice. Small cells were deployed within factory premises. The problem of stable network access was solved in a way, but another problem cropped up. It is about time. If the data needs to be backhauled via the mobile core network, then the latency of the data exchanged can be high and can even vary. And the latency also depends on the network congestion which is difficult to predict even with the best performance monitoring and business intelligence tools.

In 5G, the problem had been addressed in an eloquent fashion. A dedicated slice of the RAN (Radio Access Network) or core network is deployed by the mobile operator in the factory premises that manages the network access and data communication between their nodes or application servers. The slice is owned by the mobile operator and connected to the 5G core mainly for signalling data exchange (for slice selection, data bearer management, network authentication, real time charging). But the traffic data stays local. As the traffic pattern can be well predicted and the data does not get backhauled to the core network of the mobile operator, the time to communicate can be predetermined to a good extent. So did the 5G Network Slicing solution solve all communication problems for the industry 4.0 folks? Well there is a mixed reaction.

For the manufacturing and automotive industry players, it may not be enough. For many reasons. Come to data security first. Even if the network slices are deployed by the mobile operators in factories or alongside the roads and highways for car manufacturers, user data information is still routed outside their walled garden. So in case the mobile access or core network is compromised, it can have a detrimental impact on end to end security for the industry ecosystem. Second, the ‘lock in’ with the mobile operators is not fancied by many. Other factors can also play a role. For example the high operational cost for maintaining slices as well as data usage. Customisations that may be needed for integration with the automation and AI systems can be a potential bottleneck.

So what can be an alternative option? Many industry players like Bosch, BMW are contemplating the option of deploying private 5G networks that can overcome all the hurdles. To make matters simpler for them, ITU has allocated a private Mobile Country Code (999) that can be shared by multiple players provided the usage stays within a limited geographical area. But it can still be a costly affair. It is not just about the cost of deploying a 5G core and access network. It is also about acquiring the spectrum. If the 5G RAN has limited access only within the periphery of the factory (say), then they may bid for a license exempt. But this depends on the country of operations. However, this may not work for the car industry, as the cars can roam pan world. In such a case, a global deployment makes more sense, implying use of a dedicated spectrum or a shared spectrum.

Mobile network operators are endorsing the idea of 5G network slices. The industry players are the protagonists for 5G private networks. Whose idea will prevail? We need to find a crystal ball.

Rajarshi Sanyal is a telecommunication network architect at BICS (Belgacom International Carrier Services) based in Brussels, Belgium. He is one of those leading innovation and architectural initiatives in the domain of 5G, IoT, VoLTE, to name a few. He obtained Ph.D. from Aalborg University, Denmark on future mobile networks. He has 5 patents and 28 research publications in the field of telecom.

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