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Network Slicing is a great concept which has always been an attractive jargon for vendors who wish to bundle it with products to sell their products and solutions . However with the arrival of 3GPP Release16 and subsequent products arriving in market things are starting to change ,with so many solutions and requirements finding a novel slicing architecture that fits all is both technically complex and business wise not making lot of ROI sense . Today we will try to analyze and answer the latest progress and directions to solve this dilemma

Slicing top challenges

Based on our recent work in GSMA and 3GPP we believe below are the top questions both to evolve and proliferate slicing solutions

• Can a Public Slicing solution fulfill vertical industry requirements
• How to satisfy vertical industry that Slicing solution can fulfil their needs like data sovereignty , SLA , Security , Performance
• Automation and Intelligence , can a public slicing solution flexible enough to provide all intelligence for each industry
• Slicing for cases of 5G Infra sharing

Solution baseline principles

When we view Slicing or any tenant provisioning solution it is very important as E2E all layers including business fulfillment , network abstraction and Infrastructure including wireless adhere to the same set of principles .

A nice description of it can be found in 3GPP TS28.553 about management and orchestration for Network slicing and 3GPP TS28.554 KPI for 5G solutions and slicing . In summary once we take the systems view for Network Slicing the principles can be summarized to following

• Slice Demarcation: A way to isolate each tenant and a possibility to offer different features of slicing bundle to different tenants , for example a Large enterprise with 10 features and 20 SLA while for small businesses 5 features and 5 SLA will do
• Performance: A way to build a highly performant system , the postulate is once we engineer and orchestrate it will it work E2E
• Observability : With 4B+ devices added every year and with industry setting a futuristic target of a Million Private networks by 2025 its just a pressing issue how to observe and handle such networks in real time

I think when we talk about Slicing mostly we speak about key Technology enablers like NFV , Cloud , MEC , SDN which is obviously great since a software of Network and Infra is vital . However not speaking about RAN #wireless and WNV (Wireless Network virtualization) is not a just . In this paper i just want to shed some light from RAN perspective , consider the fact still today around 65% of customers CAPEX/OPEX pumping in RAN and Transport it is vital to see this view for both conformant and realistic solution . if NFV/SDN/Cloud demands sharing among few 100’s tenants the RAN demands sharing among Million so resource sharing , utilization and optimization is vital

RAN Architecture

From E2E perspective the RAN part of slice is selected based on GST and NSSAI which is done by UE or the Core Network however its easier said than done when we need to view E2E Slicing following should be considered to build a scalable slicing solution

RAN#1: Spectrum and Power resources

The massive requirements for business towards services and slices require a highly efficient Radio resources , luckily low,mid and high bands combined with Massive Mimo is handling this part however not just spectrum and how to utilize this in efficient manner in form of form factor and power is vital . When we need view RAN view of Slicing its not just the Spectrum it self or RF signal but also the Spectrum management like Macro , Femto and Het Nets including Open cellular . In summary still this part we are not able to understand well as it require some novel algorithms like MINLP (mixed integer non linear) programming which focus to optimize cost while increase resource usage at same time . As per latest trend a tiered RAN architecture combined by new algo like game matching through ML/AI is the answer to standardize this

RAN#2: RAN Dis-aggregation

Just like how NFV/SDN and Orchestration did for Core similarly Open-RAN and RIC (RAN intelligence controller ) will do for RAN . If you want to know more may be you need check author’s writeup about RAN evolution

RAN#3 RAN resource optimize

Based on our Field trials we find the use of Edge and MEC with RAN and specially for CDN will save around 25% of resources , the RAN caching is vital combined with LBO( Local break out) will help Telco’s fulfill the very pressing requirements from verticals . Again this is not just a cloudlet and software issue as different RAN architectures require a different approach like D2D RAN solution , Het Net and macro etc

RAN#4 Mid Haul optimize

Mid haul and Back haul capacity optimization is vital for slicing delivery and today this domain is still in a R&D funnel . A TIP project CANDI Converged Architectures for Network Disaggregation & Integration is some how evolving to understand this requirement

RAN#5 Edge Cost model

Edge solution for Slicing in context of RAN is cost model problem e.g how many MEC servers and location and it can relieve RAN and RF layer processing is the key , our latest work with Telco Edge cloud with different models for different site configuration is the answer

RAN#6 Isolation , elasticity and resource limitation

This is the most important issue for RAN slicing primarily due the the fact that they are different conflicting dimensions viz. extra resource isolation may make impossible to share resources and will limit services during peak and critical times , similarly much elasticity will make isolation and separation practically impossible , solutions for matching algorithms is the answer as it will help to build a RAN system which is not only less complex but also highly conformant . This is a make and break for RAN architecture for slicing

RAN#7 RAN infrastructure sharing for 5G

Today already the Infra sharing has started between ig players in Europe , the one questions that comes what about if a use purchase a slice and service from a tenant ,consider a whole sale view where the Infra is processed by sharing and bundling of resources from all national carriers due to reason that obviously the 5G infra from single operator is not sufficient from both coverage and capacity perspective

RAN#8 RAN Resource RAGF problem

In case of service mobility or congestion how UE can access the resources quickly may be in other sector or sites

RAN#9 Slice SLA

SLA of slices and its real time monitoring is the key requirements of business , however imagine a situation where shortage of shared resource pool make impossible to deliver the SLA

RAN#10 Slice Operations

Slice operations is not just the view of BSS and Operations as real time RAN resource usage and optimization is necessary , Have you ever thought how perfectly managed slice can exist with normal Telco service specially when you find there is a key event and many users will use service . I think this so some dimension still not well addressed . I have no hesitate to say when many CXO’s of enterprise convince them they should opt to build their own 5G private network this is exactly the problem they fear .

Summary

In today’s writeup i have tried to explain both the current progress, challenges and steps to build a successful slicing solution keeping the hat of a RAN architect , i believe this is very important to see the Radio view point which somehow i firmly believe has not gotten its due respect and attention in both standard bodies and by vendors , in my coming blog i shall summarize some key gaps and how we can approach it as still the slicing products and solutions are not carrier grade and it need further tuning to ensure E2E slicing and services fulfillment .