It's well known that primary objective of Mobile network was to provide affordable communication services for mass market and slowly it has entered to Enterprise market as well, but main focus and earning anchor still remains the individual mobile users only. With the introduction of high speed internet offered in 4th generation mobile network (LTE), Operators and Telco vendors started looking up for new revenue resources from the Horizontal market segments, to recover the network transformation cost, such as OTT, Entertainment, Information, News, Sports etc. This gave the rise for the ICT industry, which has now been matured significantly.
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| Industry Journey So Far |
Now the 5G is in its early phase, it become important, "How Operators will get the Return on investment, they will be doing on this huge network transformation!"
It is obvious that only by catering to the Retail market and traditional IoT services, the revenue realization will not happen and CSPs will continue to struggle for getting extra bucks for their network infrastructure cost.
"CSPs need to think beyond the Horizon of adjacent market and target the new Vertical segments, such as Healthcare, Industry Automation(IIoT), Smart Cities, V2X etc."
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| New Target Segment for CSPs |
However, each of the Vertical industry has its own use cases, network characteristic requirements and SLAs, which are very different not only from the current Telco use cases, but also from that of other verticals as well. For example: For an Automotive Production plant, the Bandwidth requirements are very tiny and they don't require extreme Mobility, but their main requirement is to connect Millions of devices per Square Km. and a very long (~10years) UE battery life. In another example of V2X or Connected Car segment, the main requirement is the extreme connectivity over the longer distance and superior mobility handover, typically between the heterogeneous Radio-Access-Networks and they also don't require a very high data rates. To complex things a bit more, let us introduce another use case of Remote Healthcare, where the requirement is not a great mobility experience, but a good bandwidth (100Mbps which is available in LTE as well) and a guaranteed Sub-Millisecond end-to-end latency.
Based on various industry use cases and SLA requirements, 3GPP has categorized the 5G use cases into 3 segments, namely:
eMBB: Enhanced Mobile Broadband (Gigabit Mobile Internet)
mMTC: Massive Machine Type Communication (~1Mn Connections per Sq-Km and 10 Years UE battery life)
URLLC: Ultra Reliable & Low Latency Communication (<10ms Latency, Tactile Internet, Immersive Experience)
If you need more detailed view on each of these segments, please checkout my earlier article here, since current write-up will be more focused on Network Slicing.
From above, its evident that a single network could simply not deliver everything out of it and we need to have a different approach and thought process to cater these requirements, the "Use case driven methodology"!
"5G deployments are driven by Use cases and not the other way around, unlike its predecessors!"
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| 5G Three-Dimensional Use Cases and Requirements |
What it means is that CSP should not deploy the 5G network first and then define the use case, it is capable to serve, but they should first define the use case and the SLAs, network-Characteristics requirements etc. and then design a specific network around it. But they simply can't have different networks for different use cases or can they? Actually they can! They don't need to have different physical networks for different use cases, instead they will be having logically separated networks, based on different use cases. This is where the concept of Network Slicing becomes not only relevant, but also necessary to implement.
"Term Network-Slicing essentially means set of logical Network-Functions grouped together to deliver specific service (or set of services), such that for the consumers it looks like a complete network!"
Network Slicing can be Horizontal and Vertical, based on the Service-Delivery requirements. For example: Only Access Network can be designed as a Slice to deliver only Radio Connectivity for a specific segment or a complete end-to-end Slice, containing Access and Core-Network NFs, for a Communication-Service.
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| Horizontal Network Slicing |
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| Vertical Network Slicing |
So, how does Network Slicing work? Well Network-Slicing is not a new concept, we have been unknowingly doing it for more than a decade, but in 5G, specially when talking about Vertical segment use cases, Network-Slicing is to be used at its full potential. Till 4G, we used to slice the Core network by use of APN (Access Point Name) and Location (MCC, MNC, LAC etc.). Here, different Core Network-Elements (SGSN, SGW, PGW, GGSN etc.) used to serve for different APNs, typically different for Voice and Data; and that's it!
However, in 5G Network-Slicing is more matured and essential Tech-tool, which allows CSPs to use each of their Network-Functions (Access and Core) efficiently, by diversifying different Slices. The idea of Network slicing is to Dynamically define the Slices and automatic creation and deletion of Network-Slices, driven by the service-requirements to deliver the efficiency & SLAs, which Service demands and optimize the CAPex/OPex at the same time.
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| Network Slicing Management |
Above figure shows, how a Network-Slicing-Management framework looks like. As already explained above, 5G is a Use case driven technology, hence, the flow of Network-Slicing is also in the same line and it works from Top to bottom, i.e Use case triggers the network-requirements and network creates a network-slice (or use existing one) and after the usage is ended the network deletes the slice to minimize the resource utilization.
Let us now understand in detail, how exactly the network slicing works! When a new Communication/Network Service is triggered, the CSMF checks, if it has a Service-Instance available, which matches the characteristics of the requested service, if yes, it simply align the Service with that Service-Instance. If that is not the case, CSMF instantiates a new Service-Instance, which maps to an available Network-Slices. In case the CSMF could not find a suitable Network-Slice, it requests the NSMF to instantiate a new Network-Slice for the given Service-Instance Characteristics. CSMF will then creates an NST (network-Slice-Template), which contains the network-characteristics & NF requirements and maps the same with available Sub-Network-Instances to create a new Network-Slice and respond back to the CSMF with the new Slice information. In case CSMF could not find the available Sub-Network-Instances, matching with the requirements of NST, it then requests to NSSMF to create a suitable Sub-Network-Instance for the given NST and finally NSSMF may create a new Sub-Network-Instance from the available set of NFs or it may instantiate one or more NFs from the available Resources. This is a typical flow for the Network Slice Life-cycle Management.
Here it is important that based on the operator defined configuration, Management Functions (CSMF, NSMF, NSSMF) can decide to delete or retain a particular network slice after the delivering the service. For instance, a Radio-Access-Network Slice for a Football ground can be dynamically created only for 3 hours match time and after that it can be deleted and the available resources, NFs can be aligned to some other Network-Slice.
Key Take away:
- Network Slicing is a methodology to design dynamic logical networks, derived from the service requirements
- A fine-grained network resource Optimization
- Network Slicing is not MVNO, but MVNO can be a Network-Slice example
- Network Slices can be Horizontal and Vertical
- One Network-Slice can serve more than one Service
- One Network-Function can be included in more than one Network-Slices
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