02_RRM_overview_RAS06_v1.0

1 Nokia Siemens Networks Presentation / Author / DateI insert classification level

Course Content

Radio Resource Management OverviewParameter ConfigurationCommon Channels & Power ControlLoad ControlAdmission ControlPacket Scheduling incl. HSPAHandover ControlResource Manager

2 Nokia Siemens Networks Presentation / Author / DateSoc Classification level

Module Objectives

At the end of the module you will be able to: Describe the purpose of RRM List the RRM functional entities Describe the purpose of each of the RRM functional entities Identify the location of RRM entities Identify relationships between RRM entities


Radio Resource Management Overview

Introduction Load Control (LC) Admission Control (AC) Packet Scheduler (PS) incl. HSPA Power Control (PC) Handover Control (HC) Resource Manager (RM)


Radio Resource Management

Target for RRM is to ensure the RAN offers: The planned coverage for each targeted service High capacity i.e. low blocking (new calls, handovers) The required Quality of Service (QoS) Optimize the use of available capacity (priorities)By continuously monitoring/adjusting how the available resources are used in

accordance with user requests


RRM Tasks

RRM must be able to: Predict the impact on interference (power) of

the admitting a new user for UL & DL Perform appropriate actions (e.g. new call

admissions, bitrate increase/decrease etc.) in accordance with prevailing load conditions

Provide different quality of service for real time (RT) and non-real time (NRT) users

Take appropriate corrective action when the different cell load thresholds are exceeded in order to maintain cell stability (i.e. load control)

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RRM is made up of a number of closely interdependent functions (i.e. algorithms)

These functions can be divided into;

Cell Based Load control (LC) Admission control (AC) Packet scheduling (PS) High Speed Downlink Packet Access Resource manager (RM)

Connection Based Handover control (HC) Power control (PC)

RRM Functional Split

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Load control States

The load control function within RRM can be divided: Preventative load control (e.g. congestion) Overload control (e.g. dropping of calls in worst case)

Preventative actions are performed before the cell is overloaded (threshold y) Overload actions are performed after cell is overloaded (threshold x) RNP parameters define the thresholds for the RRM functionalities The thresholds define a stable functionality within a cell and with surrounding

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Load Control

LC performs the function of load control in association with AC & PS

Updates load status using measurements & estimations provided by AC and PS

Continuously feeds cell load information to PS and AC; Interference levels

BTS power levels Non-controllable load

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Introduction

Load Control (LC) Admission Control (AC) Packet Scheduler (PS) incl. HSPA Power Control (PC) Handover Control (HC) Resource Manager (RM)


Admission Control

Responsible for maximising capacity (throughput) whilst providing the required quality of service for RT traffic.

Checks that admitting a new user will not sacrifice planned coverage or quality of existing connections

Determines whether RABs can be admitted to the RAN Handles RT RABs alone by estimating the increase in non-controllable load With PS decides whether to allocate resources to NRT RABs In the decision UL interference & DL power measurements by BTS are used In RAS06 also the UL throughput is considered for AC

Provides RLC parameters to PS for NRT users, for example Bearer class Transport Formats

AC sets quality and power parameters for the radio link, for example UL/DL BLER, Eb/No targets, SIR target Initial DL transmission power


Admission Control, RAS05.1 picture In uplink the total received wideband interference power measured indicates the traffic

load of the radio resources .

For downlink the power change caused by new RT service is obtained from the maximum allowed DL transmission power for the service.

In the admission decision procedure new call (or modified existing call) is admitted if both UL and DL admission decisions are passed

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Planned load area

Marginal load area

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Admission Control, RAS06 picture, UL

Throughput thresholds are calculated from new, configurable Prx thresholds





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non-controllable loadcontrollable load

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Packet Scheduler in RNC


HSDPA - general principle

Fast scheduling is done directly in Node-B based on feedback information from UE and knowledge of current traffic state.

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Power Control

Since WCDMA system is interference limited it is beneficial to reduce transmission power as far as possible.

Thus, the target of power control (PC) is to achieve the minimum signal-to-interference ratio (SIR) that is required to offer sufficient quality of the connection.

PC works on a per-connection basis.

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Handover Control (HC) #"

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Intra-layerInter-layer

Intra-System

Soft(er) Handover

Hard HandoverInter-frequency

Intra-frequency

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Inter-System(Inter-RAT)

Hard HandoverInter-frequency

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Resource Manager (RM) Responsible for managing the logical radio resources of the RNC in co-operation with AC

and PS On request for resources, from either AC(RT) or PS(NRT), RM allocates;

DL spreading code UL scrambling code

Also looks after code tree management (to maintain orthogonality); Initial code selection codes concentrated to same branch Code de-fragmentation dynamic reallocation of codes as users enter/leave system

DL spreading code allocation for HSDPA users can be dynamic in RAS06

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Documents

02_RRM_overview_RAS06_v1.0