Capacity Managment

Capacity Management

Outline

Overview

Capacity Management Functions - Dedicated Monitored Resource Handling

- Admission Control

- Congestion Control

Overview

Capacity Management is responsible for the control of the

load in the cell. It consists of 3 main functions:

Dedicated Monitored Resource Handling: tracks utilization of critical resources of the system.

Admission Control: accepts/refuses admission requests based on the current load on the dedicated monitored resources and the characteristics of the

request

Congestion Control: detects/resolves overload situations

Congestion Control Admission Control

Dedicated Monitored Resource Handling

Parameters

Capacity Management

Overview

Capacity Management Architecture Overview

Capacity Management functionality is located in the RNC.

The controlling RNC is responsible for the load and congestion control of its cells

and the execution of the admission control.

Dedicated Monitored Resources

The Dedicated Monitored Resources Handling function is

responsible for collecting and providing information about the

utilization of resources that are critical to the load of the cell:

by performing event-based and periodic measurements

by keeping track of every link setup, addition, deletion and

modification in the cell.

Monitoring Algorithm Update Cell Load Information Downlink channelization codes Monitor

Histogram Monitor

Downlink Transmitted Carrier Power

All interface Speech Equivalents (ASEs)

Uplink Received Total Wideband Power (RTWP)

RBS hardware utilization

Measurements

Dedicated Monitored Resource Handling


Resources monitored under the Capacity Management scope:

Downlink Channelization Codes Monitor: provides a measure for code tree utilization in DL.

Histogram Monitor: keeps track of

- SF usage in the DL: tracks the number of connections using a certain

SF (except SF=16, reserved for HSDPA connections).

- SF usage in the UL

- Number of Compressed Mode radio links: used to avoid too much

interference from the compressed mode radio users.

- Number of users allocated to the HS-DSCH

Downlink Transmitted Carrier Power Monitor: monitors the total amount of Non-HS downlink transmitted carrier power in the cell.

All interface Speech Equivalent (ASE) Monitor: accounts for the air interface resources usage for DL and UL. The ASE of a radio link

depends on the connection type and is expressed in terms of the

equivalent number of speech radio bearers that generate the same

amount of air interface load.

Uplink received total wideband power (RTWP): provides information to Congestion Control regarding uplink interference.

RBS Hardware Monitor: HW is a limited resource that depends on the amount of installed HW (channel elements) and the licensing

restrictions.


Admission Control

Admission control accepts or refuses requests for utilization of dedicated

monitored resources. It is performed on cell basis.

The admission requests are initiated when:

- A new connection is set up.

- An existing connection is modified.

- Soft Handover is performed.

The request for admission specifies the amount of resources that the

radio connection requires:

- Setup type: handover or new connection.

- Service Class: guaranteed, guaranteed-hs or non-guaranteed service.

- Compressed mode resources requested if any.

- Downlink Transmitted Carrier Power requested if any.

- Downlink Channelization Code resources requested if any.

- ASEs in uplink and downlink if any.

The requirements are compared to the available resources and the configured

limits for admission and the access is granted or denied.

Admission Control

RAB request over the Iur interface

1. RAB request sent from SRNC

to CRNC by means of RNSAP

message over the Iur interface.

2. RNSAP is converted into RBs

and DCHs attributes.

3. Required monitored resources

are estimated on the basis of

the set of DCHs and admission

requested for those resources.

4. If request is admitted, the

CRNC allocates necessary

resources.

5. Admission Control informs

SRNC by means of RNSAP

message.

Admission Control

Non-guaranteed

Traffic class background or

interactive

(Example: FTP and internet

web services)

Guaranteed

Traffic class conversational or

streaming

(Example: speech and video

services)

Guaranteed-hs

HSDPA service

Non-

Handover

Best effort services. New

connections.

New connections New connections.

Handover Best effort services. Add radio link for existing connections in

new cells.

Add radio link for existing

connections in new cells.

Add radio link for

existing connection in

new cell.

Admission control is responsible for

- Dividing the available resources among the non-guaranteed connections.

- Differentiating access to guaranteed, guaranteed-hs and non-guaranteed

connections.

- Reserving part of the dedicated monitored resources for handover

connections.

Combinations of requests for admission depending on setup type and service class

Non-guaranteed admission requests are

blocked when

DL Code Usage > dlCodeAdm -

beMarginDlCode

Guaranteed admission requests are

blocked when

DL Code Usage > dlCodeAdm

Code blocking for non-handover requests is performed to reserve codes for users in

handover.

Admission Control

The Downlink Channelization Code Admission Policy

When a request is blocked on the downlink channelization code admission, the soft

congestion mechanism is triggered.

No.

DlCodeAdm

(%)

beMarginDlCode

(%) Result

1 2 0 RRC Connection Setup Rejected

2 3 0 RRC Connection Setup Rejected

3 4 0 Voice call admitted, PS call rejected

4 35 0 Voice call admitted, PS call rejected

5 37 0

SRB admitted, PDP context

activation rejected.

6 39 0

SRB admitted, PDP context

activation rejected.

7 40 0 PS Call admitted up to 384 Kbps

Admission Control

Trial: Downlink Code Admission

Settings:

beMarginDlCode=0

DlCodeAdmin=variable

Results:

Controls the SF usage in DL and UL at cell level, the number of radio links in

compressed mode and the number of simultaneous HS-serving links in a cell.

Admission Control

The Histogram Admission Policy

Requests demanding SF8 are blocked

when usage of SF8 > sf8Adm





Non-guaranteed Service Class in DL

Admission Control

Guaranteed Service Class in DL

Requests demanding SF16 in DL (streaming PS16/128 radio connection type)

are blocked when usage of SF16 > sf16gAdm

Guaranteed-hs Service Class in UL

Requests demanding SF4 in UL (PS384/HS radio connection type)

are blocked when usage of SF4 > sf4AdmUl

By setting this parameter, the access for high and low consuming guaranteed

services can be differentiated.

In cells where the optional PS384/HS radio connection is activated, this

parameter may be reduced if the uplink experiences problems.

The Histogram Admission Policy (cont)

Admission Control

Compressed Mode Radio Links Limits

Requests demanding a radio link in compressed mode are blocked when

Current number of radio links > compModeAdm

Number of Simultaneous HS-Serving Links Limits

The number of users allocated to the HS-DSCH may be limited to ensure sufficient

end-to-end quality. Admission request will be blocked when

number of users assigned to the HS-DSCH > hsdpaUsersAdm

The Histogram Admission Policy (cont)

The presence of connections using SF/2 compressed mode may degrade the quality

of the common channels. That may be avoided by adjusting compModeAdm.

Admission Control

Trial: Histogram Admission

Settings:

sf32Adm= 32

sf16Adm= 16 , 8

sf8Adm= 8 , 0

Results:

No. sf32Adm s16Adm sf8Adm Max Throughput (Kbps)

1 32 16 8 384

2 32 16 0 128

3 32 0 0 64

Admission Control

The Downlink Transmitted Carrier Power Admission Policy

Non-Guaranteed, Non-Handover requests are

blocked when

DTCP > pwrAdm - beMarginDlpwr

Guaranteed, Non-Handover & Non-Guaranteed,

Handover requests are blocked when

DTCP > pwrAdm

Guaranteed, Handover & Guaranteed-hs

requests are blocked when

DTCP > pwrAdm + pwrAdmOffset

This admission policy controls the downlink power utilized by R99 connections.

When a request is blocked on the DL Transmitted Carrier Power policy, the soft

congestion mechanism is triggered.

No. pwrAdm (%)

beMarginDlPwr

(%)

pwrAdmOffset

(%)

maxPwrMax

(dB) Result

1 13 0 0 4.8 RRC Connection Setup Rejected

2 16 0 0 4.8 RRC Connection Setup Rejected

3 17 0 0 4.8

Signalling Radio Bearer admitted,

but PDP context activation blocked

4 18 0 0 4.8 PS call admitted up to 64Kbps

5 18 0 0 15 PS call admitted up to 384Kbps

Admission Control

Trial: Downlink Transmitted Carried Power Admission

Settings:

beMarginDlPower=0

pwrAdmOffset=0

pwrAdm=variable

maxpwerMax=15

Results:

Admission Control

The ASE Admission Policy

Provides information of air interface usage per radio link type in cell for DL and UL.

The UL ASE Admission Policy


blocked when

ASE UL Usage > aseUlAdm - beMarginAseUl


Handover requests are blocked when

ASE UL Usage > aseUlAdm

Guaranteed, Handover & Guaranteed-hs requests

are blocked when

ASE UL Usage > aseUlAdm + aseUlAdmOffset

ASE is the only resource for admission control on the UL

The DL ASE Admission Policy


blocked when

ASE DL Usage > aseDlAdm - beMarginAseDl

Non-Guaranteed, Handover & Guranteed &

Guaranteed-hs requests are blocked when

ASE DL Usage > aseDlAdm

Admission Control

Admission Control

Trial: ASE Admission

Settings:

dlCodeAdm=100

beMarginDlCode=0

beMarginAseUl=0

aseUlAdm=500

beMarginDlPwr=0

Results:

No aseDlAdm Result

1 1 CS Voice rejected, PS Rejected

2 2 CS Voice rejected, PS Rejected

3 3 CS Voice admitted, PS Rejected

4 9 PS call admitted up to 64Kbps



Admission Control

The RBS Hardware Admission Policy


blocked when

UL HW Usage > ulHwAdm - beMarginUlHw


Handover & Guaranteed-hs, Non-Handover

requests are blocked when

UL HW Usage > ulHwAdm

Guaranteed, Handover & Guaranteed-hs,Handover

requests are blocked when UL HW usage arrives

at 100%

Provides information of hardware usage in a local cell group for DL and UL

The UL RBS Hardware Admission Policy

Admission Control

The DL RBS Hardware Admission Policy


blocked when

DL Hardware Usage > dlHwAdm - beMarginDlHw


Handover & Guaranteed-hs, Non-Handover requests

are blocked when

DL Hardware Usage > dlHwAdm

Guaranteed, Handover & Guaranteed-hs,Handover

requests are blocked when DL HW usage arrives at

100%

When a request is blocked on the DL RBS Admission, the soft congestion

mechanism is triggered.

Admission Control

Soft Congestion Mechanism

The Soft Congestion Mechanism is triggered when a request for

admission is blocked.

This mechanism consists of down-switching an non-guaranteed

connection to a lower rate after

a guaranteed admission control is blocked a guaranteed-hs admission control is blocked a non-guaranteed admission control of a lower rate is blocked

The Soft Congestion mechanism targets connections originating

over the Iu interface (present product not able to down-switch

connections originating over the Iur interface)

Admission Control

Soft Congestion Mechanism (cont)

Soft congestion triggered by non-guaranteed request blocking

The rate of an existing connection is reduced depending on the requested

downlink rate:

request for 384 kbps blocked not affect existing connections in cell request for 128 kbps blocked reduce exiting 384 kbps to 128 kbps request for 64 kbps blocked reduce 384 kbps to 128 kbps or (if not 384 kbps connections available)

reduce 128 kbps to 64 kpbs

Soft Congestion triggered by guaranteed request blocking

The non-guaranteed connections are targeted in decreasing order of their

downlink rate (first 384 kbps connections are reduced, then 128 kbps

connections are targeted, )

Congestion Control

Congestion Control Detection

Congestion is detected in the RNC by means of

measurements of the Downlink Transmitted Carrier Power

and the Uplink Received Total Wideband Power.

The Downlink Transmitted Carrier Power is continuously

measured. When the power goes above a predefined

threshold, an eventbased measurement is sent to the

RNC. As long as the power is above the threshold, an

event based report is sent to the RNC every second.

DL Cell Congestion Detection

Congestion Control

DL congestion is solved when the DTCP is below the setup threshold for longer

that the hysteresis time or until next periodic event-based measurement

indicating DTCP below threshold arrives.

Congestion Control

UL Cell Congestion Detection

UL congestion is solved when the Uplink RTWP is below the setup threshold for

longer that the hysteresis time or until next periodic event-based measurement

indicating URTWP below threshold arrives.

Congestion Control

Congestion Resolve Handling

Congestion Control

Non-guaranteed connections are targeted immediately: their

rate is decreased

If congestion persists and there are no more Non-guaranteed

connections, the resolve actions start for Guaranteed-hs

connections. They will be dropped.

The guaranteed services are the last ones to be targeted by

Congestion control. The resolve actions on Guaranteed services

are more severe, causing the drop of the connections.

Congestion resolve actions in mixed services congested cell:

Thank you for your participation!

Documents

Capacity Managment