A Programmable Distributed Optimization Framework for 5GPCI and (C)ANR optimization • Physical cell ID (PCI) is a locally unique integer ID in 4G/5G o Used for handoff and physical

A Programmable Distributed

Optimization Framework for 5G

Dilip Krishnaswamy (Reliance Jio)

Swaminathan S (Wipro)

ICSDN 2019

Aug 10th, 2019

Food for thought?

“The Americans have need of the telephone, but we do not. We have plenty of messenger

boys.”

- Sir William Preece, Chief Engineer, British Post Office, 1876

“When wireless is perfectly applied the whole earth will be converted into a huge brain,

which in fact it is, all things being particles of a real and rhythmic whole. We shall be able

to communicate with one another instantly, irrespective of distance. Not only this, but

through television and telephony we shall see and hear one another as perfectly as though

we were face to face, despite intervening distances of thousands of miles; and the

instruments through which we shall be able to do his will be amazingly simple compared

with our present telephone. A man will be able to carry one in his vest pocket.”

- Nikola Tesla, 1926

What is 5G?

Speed of >1

Gbps, latency

1 ms

Closed

control

loops,

Cognitive

Able to support

eMBB, mMTC,

URLLC use

cases

Programmable

(SDN/NFV)

NR,

disaggregated

RAN

Flexible and

context-aware

Outline

Pre-

requisit

es

Orchestrati

on

Software-

defined

RAN

Self

Organizing

Networks

(SON)

Network

Slicing

Optimization

SONNetwork

Slicing

Orchestration – Multi-layered

Reference: https://sdn.ieee.org/newsletter/september-2016/orchestration-and-control-solutions-in-5g

Simplified orchestration architecture

End-to-end/Service level

Domain/Network segment level

Network Functions

5G RAN Functional Decomposition (Disaggregation of RAN)

Reference: “NGMN Overview on 5G RAN Functional Decomposition”

5G RAN – Simplified Network Architecture

Reference: https://wiki.onap.org/download/attachments/10784151/ONAPNetworkSlicingv3_25Jan2018.pptx?api=v2

SD-RAN: RAN Architecture based on SDN principles

Reference: Paul Arnold, Nico Bayer, Jakob Belschner, Gerd Zimmermann, ”5G Radio Access Network Architecture Based on Flexible Functional Control / User Plane Splits”, European

Conference on Networks and Communications (EuCNC), 2017.

SDN-based RAN architecture Fully centralized CP

Self-Organizing Networks (SON)

Examples:

• PCI assignment

• ANR update

Examples:

• Mobility Load Balancing

• Mobility Robustness Optimization

Examples:

• Re-configurations

• Resource isolation, re-

initialization

Reference: https://www.reuters.com/brandfeatures/venture-capital/article?id=102160

C-SON, D-SON and H-SON

Centralized SON Distributed SON Hybrid SON

Reference : http://tec.gov.in/pdf/Studypaper/Self%20Organising%20Network.pdf

PCI and (C)ANR optimization

• Physical cell ID (PCI) is a locally unique integer ID in 4G/5G

o Used for handoff and physical layer design

o PCI ranges are LTE: 0-503, 5G: 0-1007)

• Objective is to assign PCI values to avoid PCI collision and PCI confusion

• Automated Neighbor Relations (ANR) builds & maintains neighbor relation tables in eNodeB and gNodeB

o Distributed ANR in eNB (4G), gNB (5G)

o Centralized ANR optimizes neighbor tables based on global information

• PCI needs to be re-optimized if neighbor relationship changes, (e.g. during distributed ANR function in RAN)

• PCI (re)allocation is an optimization problem with objective to allocate PCIs s.t. collisions and confusions are minimized with additional constraints for e.g.:

o Use minimum PCI values

o Change minimum number of assigned PCI values

• PCI optimization could be done jointly with ANR actions (blacklisting a neighbor from HO)

Reference: https://wiki.onap.org/download/attachments/68539437/OOF_PCI_Dublin_POC_Demo_20190724_v_2.0.pptx?version=1&modificationDate=1564034905299&api=v2

(Closed) Control Loop concept

• Key element of orchestration for automation of network operations

• Service/Slice Lifecycle Management (LCM)

o Design

o Instantiation

o Scaling (up/down)

o Modification

o Healing

o Termination

• Resource Orchestration

• Allocation

• Scaling (up/down)

• Re-allocation


Introduction to Open Network Automation Platform (ONAP)

ONAP Dublin Architecture

OSS / BSS / Other

Run-Time

External APIs CLI

SharedServices

Audit (POMBA)

Optimization (OOF)

Multi-Site State (MUSIC)

Logging

Microservice Bus (MSB) / Message & Data Routers (DMaaP)

Design-Time

Catalog

O&M Dashboard (VID) Interfaces

Service Design & Creation (SDC)

Du

blin

Legend

AuthN/AuthZ (AAF)

External Systems

Network Function Layer

Hypervisor / OS Layer OpenStack Commercial VIM Public Cloud

…

Third Party Controllers

Kubernetes

VNFsPNFs

PrivateEdge Cloud

PrivateDC Cloud

IPMPLS Man

aged

En

viro

nm

ent

sVNFM EMS

ONAP Shared Utilities

CCSDK

Model Utilities PublicCloud

& Others … …

TOSCA Parser

Portal Use-Case UI

ONAP Operations Manager (OOM)Manage ONAP

DCAE Design Studio

xNF Onboarding

Service/xNF Design

Workflow DesignerController Design

Studio

Infrastructure

Adaptation

(Multi-VIM/

Cloud)

Virtual

Function

Controller

(VFC)

Data Collection

Analytics &

Events (DCAE)

Correlation

Engine (Holmes) SDN

Controller

(SDNC)

Application

Controller

(APPC)

Active & Available

Inventory (AAI)

Service

Orchestration (SO)

Policy

FrameworkExternal System

Register (ESR)

Control Loop

Automation (CLAMP)

VNF SDKVVPVNF Validation

Reference: https://wiki.onap.org/display/DW/Approved+Dublin+Architecture

ONAP-based control loop for SON

• SON Control Loop (CL)

• ONAP: Open-source platform,

with basic open-source code

• Companies can use framework

to add proprietary SON

solutions

• OOF-PCI use case Casablanca o First ONAP SON PCI use case

o PoC Demo in Dec 2018

• OOF-SON use case Dublino Added SON function: ANR

o More SON data flows: FM, PM

o PoC Demo in Jul 2019


ONAP Dublin: PCI and C-ANR use case realization

Reference: https://wiki.onap.org/display/DW/OOF-PCI+Use+Case+-+Dublin+Release+-+ONAP+based+SON+for+PCI+and+ANR

“Distributed” PCI optimization

DU1

RU11

RU12

RU1k

Central

Orchestrator

CU1

DUn

RUn1

RUn2

RUnm

CUn

DU1

RU11

RU12

RU1k

Central

Orchestrator

CU1

DUr

RUr1

RUr2

RUrm

CUr

DU1

RU11

RU12

RU1j

CU1

DUp

RUp1

RUp2

RUpq

CUp

Cluster 1 Cluster v

Distributed instance of optimizer (e.g. at edge cloud, MEC)

Central co-ordinator, conflict resolver (e.g., at Domain Orchestrator, E2E Orchestrator)

Option 1 Option 2

“Distributed” PCI optimization – Research & Deployment challenges

• Placement of local optimizers – edge cloud, ‘cluster’ of cells/Dus

• Co-ordination across local optimizers

- Addressing conflicts

- Cells on the ‘edge’ of a cluster, i.e., impacting optimization in adjacent clusters

- Assignment of allowed PCI values, esp. for edge cells

- Parallel execution vs sequential execution, synchronization aspects

• Convergence of solution

• Stability & robustness of solution (how sensitive it is to even small changes)

• Central co-ordinator versus peer-level co-ordination

• Multi-vendor scenario – interoperability, hybrid scenarios

• Use of AI/ML techniques

Network Slicing

Reference: NGMN 5G White Paper

Network Slicing – Concept of ‘‘sharing’

Reference: 3GPP TS 28.530

1

3a

3b

2

NSI Network Slice Instance

NSSI Network Slice Subnet Instance

(Simplified) Flowchart for network slice “allocation”

Instantiate a service

Determine the appropriate

NS Template

Determine whether to reuse

existing NSI or create one

Reuse?

Go to NSSI flow for each

NSSI

Map the

service to

existing NSI

Request for a NSSI

Determine whether to reuse

existing NSSI or create one

Reuse?

Determine resources to be

allocated

Return details of

existing NSSI

Assemble NSSIs and create

new NSI for the service

Allocate & configure NSSI

and return details

Yes

No

No

Yes

NSI allocation flowNSSI allocation flow

(to be repeated for each slice sub-net)

1

2

3x

4x

Step Optimization Problem

Map a service request to an appropriate Network

Slice Template(s)

Determine whether to ‘reuse’ an existing Network

Slice Instance or instantiate one

Determine whether to ‘reuse’ an existing Network

Slice Sub-net Instance or instantiate one

Determine the resources to be allocated for the

Network Slice Sub-net Instance

Network slice ‘allocation’ – optimization problem

1

2

3

4

Centralized

Multi-layered

optimization

problem

May require

iterative

approach

NP-hard

Distributed

Focus on single

layer

Local

optimization vs

global

optimization

Demarcation of

roles

Illustration

12

3a

4a

3n

4n

a

Takeaways

• SDN (and NFV) enable a lot of programmability in the network

• RAN is getting disaggregated, and architected based on SDN (and NFV) principles

• Network Slicing adds another new dimension to this already interesting eco-system

• All of this throws up numerous research, architecture, design and deployment challenges

• Focusing on optimization, there are many areas, for example:

- Known SON use cases (centralized and distributed)

- New SON use cases, beyond just the RAN

- Network Slicing

- Optimal resource allocation (with constraints): multi-site, e2e perspective to be considered

Demo video snippets

Thank You

[email protected]

[email protected]

Modify Neighbors - Illustration

Demo Steps – Add neighbors to Cell with PCI = 5

CollisionConfusion

Original neighbors After addition of 3 neighbors

Demo Steps – PCI optimization completed

Before optimization After optimization

A Programmable Distributed Optimization Framework for 5GPCI and (C)ANR optimization • Physical cell ID (PCI) is a locally unique integer ID in 4G/5G o Used for handoff and physical

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