Telecom Whitepaper Radio Resource Management Radio Admission Control Radio Bearer Control 0113 1

7/26/2019 Telecom Whitepaper Radio Resource Management Radio Admission Control Radio Bearer Control 0113 1

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Radio Resource Management

- Radio Admission Control

and Bearer Control

Radio Resource Management (RRM) is an E-UTRAN

Node B (eNodeB) application level function thatensures the efficient use of available radio resources.

RRM manages the assignment, re-assignment and

release of radio resources, taking into account single

and multi-cell aspects.

Radio Admission Control (RAC) is a sub-function of

RRM. The task of RAC is to admit or reject the

establishment requests for new radio bearers. Theestablishment of a bearer is based on the outcome of

the RAC Algorithms.

Radio Bearer Control (RBC) is also another sub-function

of RRM. The establishment, maintenance and release of

Radio Bearers involve the configuration of radio

resources associated with them. It is based on the

outcome of RBC Algorithm.

This paper primarily focuses on the admission,

establishment and maintenance of radio bearers. We

discuss a strategy for RAC and RBC, including Quality of

Service (QoS) requirements, priority levels and

provided QoS of in-progress sessions and QoS

requirements of the new radio bearer request.

White Paper


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About the Author

Pundalik Kandolcar

Pundalik Kandolcar has been an Assistant Consultant with Tata

Consultancy Services (TCS) in the Telecom group for the past six

years. He has used his experience and understanding of Access

and Bearer Control (ABC) to write this paper.

Mukesh Kumar Das has been an IT Analyst with Tata Consultancy

Services (TCS) in the Telecom Next-Gen R&D group for the last

one year. He is involved in Initiatives and Proof of Concept (PoC)

for LTE technology. He has used his experience and

understanding of RAC and RBC to write this paper.

worked as a Consultant with TCS in a

large R&D telecom account and with the Telecom Next-Gen R&Dgroup. He had significant experience in wireless access and core

technologies.

Mukesh Kumar Das

Saugata Mukherjee

The late Saugata Mukherjee


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Table of Contents

1 Introduction 5

2 Radio Admission control Algorithm 7

3 Radio Bearer Control Algorithm 9

4 Conclusion 11

5 Acknowledgement 12

6 References 12


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Abbreviations

Abbreviation/ Acronym Expansion

RRM Radio Resource Manager

eNB eNodeB or E-UTRAN Node B

RAC Radio Admission Control

RBC Radio Bearer Control

QoS Quality of Service

ABC Access and Bearer Control

LTE Long Term Evolution

GSM Groupe Spcial Mobile or Global System for Mobile

Communications

RLC Radio Link Control

MAC Medium Access Control

RRC Radio Resource Control

PDCP Packet Data Convergence Protocol

CMC Connection Mobility Control

UE User Equipment

DRA Dynamic Resource Allocation

PS Packet Scheduling

ICIC Inter-Cell Interference Coordination

LB Load Balancing

GBR Guaranteed Bit Rate

AC Admission Control

RAN Radio Access Network

ARP Allocation and Retention Priority

ERAB E-UTRAN Radio Access Bearer

QCI Quality Class Identifier

BW Bandwidth


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Radio Resource Management (RRM) Overview

Radio Resource Management (RRM) is an eNB application level function that ensures the efficient use of

available radio resources. RRM manages the assignment, re-assignment and release of radio resources

considering single and multi-cell aspects.

The primary goal of RRM is to control the use of radio resources in the system while also ensuring that the

Quality of Service (QoS) requirements of the individual radio bearers are met and the overall usage of

radio resources on the system level is minimized. The objective of RRM is to satisfy the service

requirements at the smallest possible cost to the system, ensuring optimized use of spectrum.

Long Term Evolution (LTE) RRM includes a variety of algorithms that provide services, such as power

control, resource allocation, mobility control, and QoS management to ensure the best use of available

radio resources.

RRM has various functions. Selected key functions are described in the following sections.

Radio Admission Control (RAC)

Radio Admission Control (RAC) admits or rejects establishment requests for new radio bearers.

The goal of RAC is to ensure high radio resource utilization by accepting radio bearer requests if radio

resources are available. This simultaneously ensures proper QoS for in-progress sessions by rejecting radio

bearer requests when they cannot be accommodated.

Radio Bearer Control (RBC)

Radio Bearer Control (RBC) involves the establishment, maintenance and release of radio bearers. RBC is

also concerned with the maintenance of radio bearers of in-progress sessions at the change of the radio

resource situation due to mobility and so on.

RBC is involved in the release of radio resources associated with radio bearers including at-session

termination and handover.

Connection Mobility Control (CMC)

Connection Mobility Control (CMC) oversees the management of radio resources related to idle or

connected mode mobility.

Handover decisions may be based on UE and eNB measurements. In addition, handover decisions can use

other inputs, including neighbor cell load, traffic distribution, transport and hardware resources and

operator defined policies for the account.

Dynamic Allocation of resources to UEs in both uplink and downlink (DRA)

Dynamic Resource Allocation (DRA) or Packet Scheduling (PS) allocates and de-allocates resources

including buffering and processing resources and resource blocks to user and control plane packets.


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Inter-Cell Interference co-ordination (ICIC)

Inter-Cell Interference Coordination (ICIC) manages radio resource blocks to keep inter-cell interference

under control, based on the feedback from multiple cells.

Load Balancing (LB)

Load balancing (LB) handles uneven distribution of the traffic load over multiple cells. The purpose of LB

is to influence the load distribution in such a manner that radio resources remain highly utilized and the

QoS of in-progress sessions are maintained, and call dropping probabilities are kept to a minimum.

Application RRM as a service function on the eNB can be considered in the following logical realization

form.

Radio Admission Control (RAC) admits or rejects establishment requests for new radio bearers. One of the

approach has been described below which is based on Priority Guaranteed Bit Rate (GBR).

Priority GBR Based

It is important to realize that Admission Control (AC) is not standardized shlould be, different realizations

of LTE Radio Access Network (RANs ) will run different admission control algorithms.

Radio Admission Control Algorithm

RRM Adaptation

Application RRM Service

Manages & Updates Notifics

Shared Data

Radio Stack(RRC, MAC, S1, X2 takesappropriate Procedural

action

RBMeasurements,

Contro

lPlaneInputs

Measurements

DynamicInputs

DataPlaneInputs

Queues,Pendingetc

ConfigurationInputs

NWS1 Interfaces(Access, Qos,

Mobility)

E-UTRANXP Interfaces

(Mobility)

UEsUu Interface

(Access, Profiles, Qos)

eNB System Level Inputs

Figure 2: Application RRM Logical View


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The figure above depicts an approach according to which GBR is granted based on priority and GBR

requested. The algorithm in contention situation triggers RBC in which case the allocation happens based

on allocation and retention priority (ARP) parameters.

Start

Get AvailableBW UL/DL?

GBR?Allocate

configuredmin non-GBR BW

Min BWConfigured?

Allocate MinBW to all ERABs

Sort the ERAB list

first on priority,next on GBR basis

End ofERAB list?

END

Is a variableBW UL/DL


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Pros and Cons

n High priority GBR requests are granted first.

n In contention situation, higher priority E-utran Radio Access Bearer (ERABs) can pre-empt lower priority

ones.

Pre-emption would lead to release of lower priority ERABs.Recommendations for operator use

Operators can set Quality Class Identifier (QCI) (QoS profiles) and priority levels for different customer base,

(privileged and others) and allocation would be done on priority and GBR basis. In contention situation a

higher privilege customer gets priority over lower ones and can pre-empt lower ones.

Radio Bearer Control (RBC) involves the establishment, maintenance and release of radio bearers. One of the

approach has been described below based on Fair-share.

Prioritized/Weighted Max-Min Fair Share

While the RAC is concerned with the allocation of initial bandwidth or GBR, RBC algorithm is responsible for

allocating the remaining maximum bandwidth demand. For this, the algorithm considers the overall

resource situation in the E-UTRAN, the QoS requirements of in-progress sessions and QoS requirement for

the new service

Prioritized/weighted max-min fairshare bandwidth allocation technique tries to maximize the minimum

share for non-satisfied flows. Priority/weight is considered during allocation so higher priority gets a higher

share than lower ones.

Pros:

Cons:

Radio Bearer Control Algorithm

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Start

For all active Uses getthe ERAB list. Also getavailable BW UL/DL

Create ERAB list

InitializeTotal Weight = 0

End ofERAB list?

Total Weight+=Weight

Calculate WeightWeight = (15-QoS

Priority Level)

Calculate Weighted DemandWeighted Demand =

(MAX BW-GBR)/Weight

All ERABsallocated?

Calculate FairShareFairShare=Avail

BW/Total Weights

Update availableBW UL/DL

For all ERABs whoseWeighted Demand

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Telecom Whitepaper Radio Resource Management Radio Admission Control Radio Bearer Control 0113 1