Capacity Managment
description
Transcript of Capacity Managment
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Capacity Management
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Outline
Overview
Capacity Management Functions - Dedicated Monitored Resource Handling
- Admission Control
- Congestion Control
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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
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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.
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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
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Dedicated Monitored Resources
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
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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.
Dedicated Monitored Resources
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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.
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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.
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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
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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.
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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:
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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
Requests demanding SF16 are blocked
when usage of SF16 > sf16Adm
Requests demanding SF32 are blocked
when usage of SF32 > sf32Adm
Non-guaranteed Service Class in DL
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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)
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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.
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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
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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.
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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:
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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
Non-Guaranteed, Non-Handover requests are
blocked when
ASE UL Usage > aseUlAdm - beMarginAseUl
Guaranteed, Non-Handover & Non-Guaranteed,
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
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The DL ASE Admission Policy
Non-Guaranteed, Non-Handover requests are
blocked when
ASE DL Usage > aseDlAdm - beMarginAseDl
Non-Guaranteed, Handover & Guranteed &
Guaranteed-hs requests are blocked when
ASE DL Usage > aseDlAdm
Admission Control
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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
5 19 PS call admitted up to 128Kbps
6 41 PS call admitted up to 384Kbps
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Admission Control
The RBS Hardware Admission Policy
Non-Guaranteed, Non-Handover requests are
blocked when
UL HW Usage > ulHwAdm - beMarginUlHw
Guaranteed, Non-Handover & Non-Guaranteed,
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
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Admission Control
The DL RBS Hardware Admission Policy
Non-Guaranteed, Non-Handover requests are
blocked when
DL Hardware Usage > dlHwAdm - beMarginDlHw
Guaranteed, Non-Handover & Non-Guaranteed,
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.
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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)
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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, )
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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.
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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.
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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.
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Congestion Control
Congestion Resolve Handling
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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:
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