01 Rn31631en40gla0 Ranpar1 Rrm Overview v1.2 Ru40.Pptx

RANPAR 1 RN 3163-40A Nokia Siemens Networks

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Course Objectives

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Explain how NSN RRM is working, what is measured, when & where

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Describe the purpose of each RRM functional entities

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Identify the relations between different RRM functional entities

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Describe the parameter database structure

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Describe the main RRM parameters

RN31631EN40GLA0

Course Content Radio Resource Management Overview Parameter Configuration Common Channels & Power Control Load Control Admission Control Packet Scheduling Handover Control Resource Manager HSDPA basics & RRM HSUPA basics & RRM HSPA+ features (Overview)

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Radio Resource Management (RRM) Overview: 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 RRM functional entity

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Radio Resource Management Radio Resource Management (RRM) is responsible for optimal utilization of the air interface resources 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 Link Quality

Cell Capacity

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RRM

Cell Coverage

RRM Tasks RRM must be able to:

Overload

• Predict the impact on interference (power) of the admitting a new user for UL & DL

Load Target

• 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 actions when the different cell load thresholds are exceeded in order to maintain cell stability (i.e. load control)

Overload Margin

  r   e   w   o    P

Time Estimated capacity for NRT traffic Measured load caused by non-controllable load (RT)

RT services must have higher quality assurance than NRT

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RRM Functional Split • RRM is made up of a number of closely interdependent functions (i.e. algorithms) • These functions can be divided into;

• Cell Based

LC

• Load Control (LC) •  Admission Control (AC)

PS

RM

 AC

• Packet Scheduling (PS) • Resource Manager (RM)

Cell based functions

• Connection Based • Handover Control (HC)

PC HC

• Power Control (PC)

Connection based functions 7

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Power Control PC • WCDMA systems are interference limited; therefore, it is beneficial to reduce transmission power as far as possible (without violating the required quality). • Thus, the target of PC is to achieve the min. SIR that is required to offer sufficient quality of the connection. • PC works on a per-connection basis.

MS 

BTS 

RNC 

Power Control

Power Control Load Control

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Power Control Handover Control Admission Control Load Control Packet Scheduler 

Load Control functions • 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 & with surrounding cells Overload threshold x  Load Target threshold y

Overload Control Preventative Load Control

Estimated capacity for NRT traffic.

  r   e   w   o    P

Measured load caused by non-controllable load (RT) Time

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Load Control LC Load change info

 AC

Load status

NRT load

PS

LC

• LC performs the function of load control in association with Admission Control AC & Packet Scheduling PS • Updates load status using measurements & estimations provided by AC & PS • Continuously feeds cell load information to PS & AC: • Interference levels

Load differentiation: Total load = • Controllable load + • Semi-controllable load + • Non-controllable load

• BTS power levels • Non-controllable load

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

Grant

• Determines whether RABs or RRC connections can be admitted • Handles RT RABs by estimating the increase in non-controllable load • In the decision UL interference & DL power measurements by BTS are used • Since RAS06 the UL throughput is considered for AC, too • UL & DL admission conditions must both be fulfilled to admit a new call or modified existing call

• Provides RLC parameters to PS for NRT users, e.g. • Bearer class • Transport Formats

•  AC sets quality and power parameters for the radio link, e.g.: • UL/DL BLER, Eb/No targets, SIR target • Initial DL transmission power

•  AC takes place in the RNC

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Admission Decision

Reject

Packet Scheduler PS •

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Packet Scheduler in RNC schedules radio resources for both UL & DL R99 NRT RABs Scheduling period defined by RNP parameters

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PS relies on up-to-date information from  AC & LC

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Capacity allocated on a needs basis using ‘best effort’ approach

power Overload threshold Target threshold

Total Load controllable load non-controllable load time

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PS allocation times need to be fast to accommodate changing conditions & accurate (up-to-date load info)

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Capacity requests sent via traffic volume measurement reports (governed by RNP parameters)

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PS comprises two parts: UE specific & Cell specific

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HSDPA & HSUPA resources are scheduled by the Node B

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Handover Control HC • HC is responsible for: • Managing the mobility aspects of an RRC connection as UE moves around network • Maintaining connection quality by ensuring UE is always served by the best cell • saving capacity

• Intra-Frequency Handovers • Softer/Soft Handover • UE simultaneously connected to multiple cells from same/different Node Bs • Mobile Evaluated Handover MEHO • Hard Handover • when Inter-RNC SHO is not possible (Iur not supported or Iur congestion) • in case of HSDPA

WCDMA F1

WCDMA F1

WCDMA F2

WCDMA F1

WCDMA F2

WCDMA F1

• Inter-Frequency Handover • can be Intra-BS, Intra-RNC or Inter-RNC • Network Evaluated Handover NEHO GSM/LTE

• Inter-RAT Handover  • Handovers between WCDMA and GSM, LTE or WLAN • Network Evaluated Handover NEHO

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WCDMA

GSM/LTE

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 Channelization Code • UL Scrambling Code Code Type Scrambling codes Channelization codes

Uplink

Downlink

User separation

Cell separation

Data & control channels from same UE

Users within one cell

• Cares about 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 from RAS06 on

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HSDPA - general principle

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Channel quality (CQI, Ack/Nack, TPC) 4

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