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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Security Level: Confidentia
www.huawei.com
Load Control Strategys
for UMTS Network
UMTS Solution Test Department
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制作胶片应学会运用多种表现形式以丰富页面或使内容更条理化
V2.0在保留V1.0内容的基础上增加了部分新的图表内容
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选用时,请保持胶片的统一风格(即同一胶片选用统一风格的图表表现)
图表颜色已经根据公司专色调配设置好,若想改变其颜色,请参照公司的颜色使用规范再自
行调配(看88页附件参考)
建议一套胶片里用色控制在4种以内
这些图库会在一定时期内更新,逐步规范和完善
Huawei conf idential
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Contents
Perface
Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm Intelligent Access Control Algorithm
Load Reshuffling Algorithm
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
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Contents
Perface
Load Control Algorithm Overview
Load Control Introduction
Load Control algorithms in different UE access phases
Load Control algorithms used on different cell load levels
Priorities Involved in Load Control
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm
Intelligent Access Control Algorithm
Load Reshuffling Algorithm
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
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Load Control Introduction
Why we use load control algorithms?
The WCDMA system is a self-interfering system. As the load of the system increases, the
interference rises. A relatively high interference can affect the coverage and QoS of established
services. Therefore, the capacity, coverage, and QoS of the WCDMA system are mutually affected.
The destination of load control algotirhms
Through the control of key resources, such as power, downlink channelization codes, channel
elements (CEs), Iub transmission resources, which directly affect user experience, load control
aims to maximize the system capacity while ensuring coverage and QoS.
Differentiated services under load control algorithms
load control provides differentiated services for users with different priorities. For example,
when the system resources are insufficient, procedures such as direct admission, preemption,
redirection can be performed to ensure the successful access of emergency calls to the network.
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Load Control algorithms in different UE access phases
Before UE access: PUC
During UE access: CAC、IAC
After UE access: LDB、LDR 、OLC
Depending on the actual phase of UE access, different load control algorithms are
used, as shown in the following figure.
PUC = Potential User Control
IAC = Intelligence Admission Control
CAC = Call admission control
LDB = Load Control Balancing
LDR = Load Resuffling
OLC = Overload Control
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Load control algorithms used on different cell load levels
Start PUC: enable UEs in idle mode to camp on cells with light load
Start IAC: increase the access rate in cells with
heavy load by some actions while ensuring the QoS
Start LDR: check and relieve basic congestion in cells
NodeB TX
power (noise)
Cell load (number of subscribers)
Start OLC: check and relieve overload
congestion in cells
Icons for different load levels
Dynamically shut down or open up cells during the
effective period of the dynamic cell shutdown algorithm
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Resources used by different load control algorithms
Load Control
Algorithm
Resources
Power Code NodeB Credits Iub Bandwidth
CAC √ √ √ √
IAC √ √ √ √
PUC √ ‐ ‐ ‐
LDB √ ‐ ‐ ‐
LDR √ √ √ √
OLC √ ‐ ‐ √
Dynamic cell
shutdown√ ‐ ‐ ‐
NOTE
–: not considered √: considered
This table lists the resources that are considered by different load control
algorithms.
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Priorities Involved in Load Control
The priorities involved in load control are user priority, Radio Access Bearer (RAB)integrated priority, and user integrated priority.
User Priority
RAB Integrated Priority
User Integrated Priority
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User Priority
ARP 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
User
Priority ERROR 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3
There are three levels of user priority (1, 2, and 3), which are denoted as gold (high
priority), silver (middle priority) and copper (low priority) users. The relation between user
priority and Allocation Retention Priority (ARP) can be set through OM command; the
typical relation is shown in the following table.
Note:
ARP 15 is always the lowest priority and is not configurable. It corresponds to user priority 3 (copper).
If ARP is not received in messages from the Iu interface, the user priority is regarded as copper.
The levels of user priority are mainly used to provide different QoS for different users, for example, setting
different Guaranteed Bit Rate (GBR) values for BE services according to different priority levels.Changes in
the mapping between ARP and user priority have an influence on the following features:
High Speed Uplink/Downlink Packet Access (HSUPA /HSDPA)
Adaptive Multi Rate (AMR/ AMR-WB)
Iub overbooking
Load control
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RAB Integrated Priority
The values of RAB integrated priority are set according to the integrated priority
configuration reference parameter:
If the integrated priority configuration reference parameter is set to Traffi c Class , the integrated
priority abides by the following rules:
Traffic classes: conversational -> streaming -> interactive -> background =>
Services of the same class: priority based on Allocation/Retention Priority (ARP) values, that is, ARP1 ->
ARP2 -> ARP3 -> ... -> ARP14 =>
Only for the interactive service of the same ARP value: priority based on Traffic Handling Priority (THP),
that is, THP1 -> THP2 -> THP3 -> ... -> THP14 =>
Services of the same ARP, traffic class and THP (only for interactive services): HSPA or DCH service
preferred depending on the carrier type priority indicator parameter.
If the integrated priority configuration reference parameter is set to ARP , the integrated priority
abides by the following rules:
ARP: ARP1 -> ARP2 -> ARP3 -> ... -> ARP14 =>
Services of the same ARP: priority based on traffic classes, that is, conversational -> streaming ->interactive -> background =>
Only for the interactive service of the same ARP value: priority based on Traffic Handling Priority (THP),
that is, THP1 -> THP2 -> THP3 -> ... -> THP14 =>
Services of the same ARP, traffic class and THP (only for interactive services): HSPA or DCH service
preferred depending on the carrier type priority indicator parameter.
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User Integrated Priority
For multiple-RAB users, the integrated priority of the user is based on the service of thehighest priority. User integrated priority is used in user-specific load control.
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Contents
Perface
Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm
Intelligent Access Control Algorithm
Load Reshuffling Algorithm
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
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Auto-Adaptive Background Noise Algorithm
Uplink background noise is sensitive to environmental conditions. Therefore, the
LDM algorithm incorporates an auto-adaptive update algorithm to restrict the backgroundnoise within a specified range:
If the temperature in the equipment room is constant, the background noise changes
slightly. In this case, the background noise requires no more adjustment after initial
correction.
If the temperature in the equipment room varies with the ambient temperature, the
background noise changes greatly. In this case, the background noise requires auto-
adaptive upgrade.
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Contents
Perface
Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Potential User Control Overview
Potential User Control Triggering
Potential User Control Procedure
Call Admission Control Algorithm
Intelligent Access Control Algorithm
Load Reshuffling Algorithm
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
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Potential User Control Overview
PUC algorithm is used to balance downlink traffic load between inter-
frequency cells.
This algorithm can be used for the UE which is in these state:
Idle mode
CELL_FACH
CELL_PCH
URA_PCH state
F2
F1
Heavy
Light
Potential UE cell selection
or reselection
This algorithm
can used intra
RNC
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Potential User Control Triggering
when the load is higher
than this threshold, it
will be consider heavy
when the load is lower
than this threshold, it
will be considered light
NOTE: PUC takes effect only in downlink.
Between the heavy
threshold and light
threshold, that means
the cell state is normal.
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Potential User Control Procedure
Depending on the load status of the current cell and neighboring cell, the cell reselection
parameters are adjusted,which are contained in SIB3 and SIB11.In this way, potential
user in heavy load cell reselects to the light load cell.
Note: The PUC algorithm consider the load of neighboring cell, if it is in heavy state, theadjusting will not happened.
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Contents
Perface
Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm
Call Admission Control Overview
CAC Based on power resource
CAC Based on Code Resource
CAC Based on CE Resource
CAC Based on Iub transmission Resource
CAC Based on Number of HSPA Users
Intelligent Access Control Algorithm
Load Reshuffling Algorithm
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
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Call Admission Control Overview
Call Admission Control (CAC) is used to determine whether the systemresources are sufficient to accept a new user's access request. If the system
resources are sufficient, the access request is accepted; otherwise, the access
request is rejected.
The admission decision is based on the following resources:
Cell code resource
Cell power resource
NodeB credits resource
Iub transmission bandwidth resource
Number of HSDPA users (only for HSDPA services)
Number of HSUPA users (only for HSUPA services)
Note: A call can be admitted only when all of these resources are available. For CAC based on all the resources, uplink and downlink are independently.
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CAC based on power resource
For power resource admission, it can based on three kinds of algorithms to suit different
application scenarios.
Algorithm 1:
Power resource admission decision based on power or interference.
Depending on the current cell load (uplink load factor and downlink transmitted carrier power)
and the access request, the RNC determines whether the cell load will exceed the threshold or not
upon admitting a new call. If yes, the RNC rejects the request. If not, the RNC accepts the
request.
Algorithm 2:
Power resource admission decision based on the number of equivalent users.
Depending on the current number of equivalent users and the access request, the RNC determines
whether the number of equivalent users will exceed the threshold or not upon admitting a new
call. If yes, the RNC rejects the request. If not, the RNC accepts the request.
Algorithm 3:
The same as the Algorithm 1, the only difference is the estimated load increment always set to 0.
Note: For power resource, regardless of which the power algorithm is used, the RRC admission thresholdis always the cell OLC threshold.
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UL Power Admission based on algorithm 1&3 for R99 cell
In the formula, ηULcch is the value of the UL common channel load factor, which defines the factor
of UL common channel resources reserved.
By comparing the predicted uplink load factor ηUL , predicted with the corresponding threshold of
different service,the RNC decides whether to accept the access request or not.
The procedure for uplink power admission decision for R99 cells as follows:
The RNC obtains the uplink RTWP of the cell and uses the formula:
The threshold relationship of different services is set as follows
to calculate the current uplink load factor ηUL , where P N is the received uplink Background
noise.The RNC calculates the uplink load increment ΔηUL based on the service request.
For algorithm 3, ΔηUL is fixed to zero, this is the only difference between algorithm 1 and algorithm 3.
The RNC uses the following formula to predict the uplink load factor:
For HUSPA cells, theDCH UL power
admission formula is
different from R99
cells.
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Different threshold for different service
Threashold name Uplink Downlink
Overload trigger threshold 95 95
Total power threshold 83 90
Handover access threshold 80 85
AMR access threshold 75 80
Non-AMR access threshold 75 80
Other services access threshold 60 75
Load reshuffling trigger threshold 55 70
LDR
Other services
AMR&non-AMR
handover
Total power
OLC
High
Low
Cell power load
Threshold
The thresholds and coresponding algorithms are used for resource management and keep system stability.
Meanwhile,different threshold expresses different serivce priority. When the power resource is
insufficiency, the effect of these thresholds wiill be emerge: the higher the threshold is , the easier to
access the network.
Note:
For the RRC connection request for the reason of emergency call,detach or registration, direct admission is used.
For the RRC connection request for other reasons, UL/DL OLC Trigger threshold is used for admission.
For the serivce RB setup request admission,coresponding thresholds in the table will be used.
For the service handover in admission, handover access threshold will be used.
For the service upsize reconfiguration admisson, the load reshuffling trigger threshold will be used.
Baseline values for thresholds
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Type B: all UEs for which this cell is not the serving
E-DCH cell,the uplink load generated by the type B
of E-DCH scheduling services is defined by
ηUL,EDCH,f ,which is fixed to zero
UL Power Admission based on algorithm 1&3 for HSPA cell
Type A: All UEs for which cell is the serving E-
DCH cell, the uplink load generated by the type A of
E-DCH scheduling services is defined by
ηUL,EDCH,s
The uplink uncontrollable load is defined as follows:
ηUL,non-ctrl = ηUL - ηUL,EDCH,s - ηUL,EDCH,f
This result will be used to adminssion control.
Since the HSUPA scheduling algorithm consumes additional uplink power resources, the
power load of the WCDMA system is always relatively high. Therefore, the CAC algorithm
combines the PBR-based decision with the load-based decision to reduce the number of
potential erroneous rejections.
The power admission for HSUPA cell. If the RSEPS measurement is deactivated, the
admission algorithm automatically changes into algorithm 2.
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The PBR admission decision for HSUPA service
The PBR-based decision is used to check whether the QoS requirement of existing users
is fulfilled. The QoS is measured on the basis of the Provided Bit Rate (PBR) of theusers. If the QoS requirement is fulfilled, new users are allowed to access the network.
As shown in the previous figure, the Scheduling Priority Indicator (SPI) of a new HSUPA user
is SPI New user .
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The PBR admission decision for HSUPA service
Decision:
The RNC admits the HSUPAscheduling services in either of the
following cases:
Formula 1, 2, or 3 is fulfilled.
Formula 4 is fulfilled.
For HSUPA non-scheduling
services, the RNC admits the
HSUPA non-scheduling servicesin either of the following cases:
Formula 1, 2, or 3 is fulfilled.
Formulas 4 and 5 are fulfilled.Where
Note:
For HSUPA serivce, either PBR or power
resource admission descision is passed, the
serivce access will be allowed.
If the PBR measurement is deactivated, the
decision formulas that involve PBR are
regarded as unsatisfied.
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UL Radio Admission Decision for DCH RAB (for HSPA cell)
Where:
For HSUPA cells, the DCH service admission decision in uplink is different from R99
cells. Uncontrollable interference must be kept within a certain range. The purpose is to ensure the
stability of the system and to prevent non-scheduling services and DCH services from seizing the
resources of HSUPA services. In this regard, the CAC algorithm combines the uncontrollable part –
based decision and the total load – based decision.
When the admission of DCH services is implemented, the following formulas apply:
The RNC admits DCH services if formulas 1 and 2 are fulfilled.
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For HSDPA cells, the
DCH DL power
admission formula is
different from R99 cells.
DL Power Admission based on power algorithm 1&3 (for R99 cell)
In the formula, ηDL_cch is the value of DL common channel load reserved coefficient, which defines
the factor of DL common channel resources reserved.
By comparing the downlink load factor ηDL,predicted with the corresponding threshold, the RNC
decides whether to accept the access request or not.
The RNC calculates the downlink load increment ΔηDL based on the service request and the current
load.
The RNC uses the following formula to predict the downlink load factor:
The procedure for uplink power admission decision for R99 cells as follows:
The RNC obtains the cell downlink TCP and calculates the downlink load factor ηDL by dividingthe maximum downlink transmit power P max by this TCP.
Note: The downlink threshold for different service see the uplink part.
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DL PowerAdmission based on Algorithm 1&3 (for HSPA Cells)
Power Increment Estimation for DCH RABThe power increment estimation for the DCH RAB in the HSPA cell is similar to the DCH RAB
in the R99 cell.
Power Increment Estimation for HSDPA RAB
The power increment estimation for HSDPA RAB ΔPDL is made on the basis of GBR, Ec/N0,
non-orthogonal factor, and so on.
The detailed information
NEXT PAGE
For algorithm 3, ΔPDL is fixed to zero, this is the only difference between algorithm 1 and algorithm 3.
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DL Radio Admission Decision for DCH RAB (for HSPA cell)
Where:
When the admission of the DCH RAB is implemented in the HSDPA cells, the following
formulas apply:
Note:
If the GBP measurement is deactivated, the GBP
involved in the decision formulas is set to 0.
Decision:The RNC admits the DCH RAB in
either of the following situations:
Formulas 1 and 2 are fulfilled.
Formulas 1 and 3 are fulfilled.
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Downlink Radio Admission Decision for HSDPA RAB
Where:
Decision: The RNC admits the HSDPA
streaming RAB in any of the followingsituations:
Formula 1 is fulfilled.
Formulas 3 and 4 are fulfilled.
Formulas 3 and 5 are fulfilled.
The RNC admits the HSDPA BE RABin any of the following situations:
Formula 2 is fulfilled.
Formulas 3 and 4 are fulfilled. Formulas 3 and 5 are fulfilled.
Note:
If the GBP measurement is deactivated, the GBP
involved in the decision formulas is set to 0.
If the PBR measurement is deactivated, the
decision formulas that involve PBR are regarded
as dissatisfied.
For the first HSDPA service accessing the cell, the
decision formulas that involve PBR are regarded
as unsatisfied.
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Power admission decision based on algorithm 2
Definition
The 12.2 kbit/s AMR traffic is used to calculate the Equivalent Number of Users (ENU) of all other
services. The 12.2 kbit/s AMR traffic's ENU is assumed to be 1.
Admission procedure The RNC obtains the total ENU of all existing users ENUtotal = ∑all_exist_user ENUi.
The RNC gets the ENU of the new incoming user ENUnew.
The RNC uses the formula (ENU total + ENUnew)/ENUmax to forecast the ENU load, where ENUmax is the
configured maximum ENU.
By comparing the forecasted ENU load with the corresponding threshold, the RNC decides whether to acceptthe access request.
Different threshold parameters is set
for different types of service
Service Type Admission Threshold
UL DCH/HSUPA
UL threshold of Conv AMR service
UL threshold of Conv non_AMR service
UL threshold of other services
UL Handover access threshold
DL DCH
DL threshold of Conv AMR service
DL threshold of Conv non_AMR service
DL threshold of other services
DL Handover access threshold
HSDPA DL total power threshold
For example, the admission of a new AMR
service in the uplink based on algorithm 2will be successful if the following formula is
fulfilled:
(ENUtotal + ENUnew)/ENUmax ≤ UL thresholdof Conv AMR service
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Typical Equivalent Number of Users
ServiceENU
Uplink for DCH Downlink for DCH HSDPA HSUPA
3.4 kbit/s SIG 0.44 0.42 0.28 1.76
13.6 kbit/s SIG 1.11 1.11 0.74 1.89
3.4 + 12.2 kbit/s 1.44 1.42 - -
3.4 + 8 kbit/s (PS) 1.35 1.04 0.78 2.26
3.4 + 16 kbit/s (PS) 1.62 1.25 1.11 2.37
3.4 + 32 kbit/s (PS) 2.15 2.19 1.70 2.60
3.4 + 64 kbit/s (PS) 3.45 3.25 2.79 3.14
3.4 + 128 kbit/s (PS) 5.78 5.93 4.92 4.67
3.4 + 144 kbit/s (PS) 6.41 6.61 5.46 4.87
3.4 + 256 kbit/s (PS) 10.18 10.49 9.36 6.61
3.4 + 384 kbit/s (PS) 14.27 15.52 14.17 9.36
Typical equivalent number of users (with activity factor to be 100%)
In the upon table, for a 3.4+n kbit/s service of HSDPA or HSUPA
3.4 kbit/s is the rate of the signaling carried on the DCH.
n kbit/s is the GBR of the BE service, and the MBR of the RT service.
When calculate ENUs in RNC, the formula will be used: ∑ENUi*AFi. ENUi is the total equivalent number of different user priority users, as show in upon table;
AFi is the active factor for different user priority users;
???
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CAC Based on Code Resource
When a new service attempts to access the network, code resource admission is mandatory.
Code resource admission is implemented as follows:
For RRC connection setup requests, the code resource admission is successful if the current
remaining code resource is enough for the RRC connection.
For handover services, the code resource admission is successful if the current remaining code
resource is enough for the service.
For other R99 services, the RNC has to ensure that the remaining code does not exceed the
configurable OM threshold ( Dl HandOver Credit and Code Reserved SF ) after admission of the new
service.
For HSDPA services, the reserved codes are shared by all HSDPA services. Therefore, the
code resource admission is not needed.
For R99 PS BE serivce upsizing reconfiguration, the Cell LDR SF reserved threshold will be used.
Note: The spread factor code consume law and admission algorithm are similar to Node B credit resource,coresponding content see CAC based on Node B Credit part.
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CAC based on Node B Credit
Definition
CE stands for Node B credit on the RNC side and for Channel Element on the NodeB side. It
is used to measure the channel demodulation capability of the NodeBs.
How to calculate the CE resource
The resource of one equivalent 12.2 kbit/s AMR voice service, including 3.4 kbit/s signaling on the
Dedicated Control Channel (DCCH), consumed in baseband is defined as one CE.
one 12.2 kbit/s AMR voice service consumes one uplink CE and one downlink CE.If there is only
3.4 kbit/s signaling on the DCCH but no voice channel, one CE is consumed.
Channel elements provide either uplink or downlink capacity for services. There are two kinds of
CE.
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CAC based on Node B credit resource
When a new service tries to access the network, the credit resource admission is
implemented as follows:
For an RRC connection setup request, the credit resource admission is successful if the
current remaining credit resources of the local cell, local cell group (if any), and NodeB are
sufficient for the RRC connection.
For a handover service, the credit resource admission is successful if the current remaining
credit resources of the local cell, local cell group (if any), and NodeB are sufficient for the service.
For other services, the RNC has to ensure that the remaining credit of the local cell, local
cell group (if any), and NodeB does not exceed the configurable OM thresholds ( Ul HandOver Credit
Reserved SF/Dl HandOver Credit and Code Reserved SF ) after admission of the new services.
For R99 PS BE serivce upsizing configuration, the LDR reserved threshold will be used.
Notes: The credit resource admission is implemented in the uplink and downlink respectively.
For detailed information about local cell, local cell group, and capacity consumption law, refers to the3GPP TS 25.433.
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SF&CE DCH consume law
Stage Rate
(kbit/s)
Uplink Downlink
SFNumber of CEs
Consumed
Corresponding
Credits Consumed SFNumber of CEs
Consumed
Corresponding
Credits Consumed
RRC
3.4 256 1 2 256 1 1
13.6 64 1 2 128 1 1
RAB
8 64 1 2 128 1 1
16 64 1 2 128 1 1
32 32 1.5 3 64 1 164 16 3 6 32 2 2
128 8 5 10 16 4 4
144 8 5 10 16 4 4
256 4 10 20 8 8 8
384 4 10 20 8 8 8
AMR4.75
128 1 1 128 1 1
AMR
12.264 1 1 128 1 1
Note: For each rate and service, the number of UL credits is equal to the number of UL CEs multiplied by 2.
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SF&CE HSUPA consume law
Rate (kbit/s)Uplink
SF Number of CEs Consumed Corresponding Credits Consumed
8 64 1 2
16 64 1 2
32 32 1.5 3
64 32 1.5 3
128 16 3 6
144 16 3 6
256 8 5 10
384 4 10 20
608 4 10 20
1450 2SF4 16 32
2048 2SF3 32 64
2890 2SF2 32 64
5760 2SF2+2SF4 48 96
Note: There is no capacity consumption law for HS-DSCH in 3GPP TS 25.433, so certain creditsare reserved for HSDPA RAB, and credit admission for HSDPA channel is not needed.
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CAC Based on Iub transmission Resource
When a new service accesses the network, Iub interface resource admission is mandatory.
For the transmission admission control in Iub interface, as shown in the Figure, bottom-up Multi-
Level Admission Control Policy is used.
A user accessing the network from a path should go through the admission of the path,
resource group, and physical port in turn. The user that passes all the admission can be
successfully admitted by the transport layer.
Physical link users consist of R99 users and HSPA users.
For R99 users, the UL and DL control admission together.
For HSPA users, the UL and DL control admission separately.
First the UL controls admission. If the UL admission for HSPA users is approved, the DL
controls admission and if the UL admission for HSPA users is rejected, the DL does not
control admission.
For BE service Iub
admisssion ,the GBR
rate is used.
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Bandwidth Reserved for Services
The RNC calculates the reserved bandwidth based on the activity factor and performs
admission control based on the reserved bandwidth. Different services use different policies.
RT services, including conversational and streaming services, are admitted at the MaximumBit Rate (MBR).
Reserved bandwidth for admission of an RT service = MBR * Activity factor, where the activity factor needs to be
set for each type of service.
NRT services, including interactive and background services, are admitted at the GBR.
Reserved bandwidth for admission of an NRT service = GBR * Activity factor
SRB services can be admitted at the GBR or 3.4 kbit/s.
Admission at 3.4 kbit/s: The bandwidth is fixed at 3.4 kbit/s. This admission mode is applicable to R99, HSDPA,
and HSUPA services.
Admission at the GBR: For R99 services, if the bandwidth of a transport channel varies between 3.4 kbit/s and 13.6
kbit/s, resource allocation and resource admission do not need to be performed again.
Reserved bandwidth for admission of SRB = 3.4k * Activity factor
In terms of common channels, EFACH services are admitted at the GBR, and other
common channel services are admitted at the MBR. Reserved bandwidth for admission of EFACH = GBR * Activity factor
Reserved bandwidth for admission of other common channel = MBR * Activity factor
Note: The activity factor can be set for different services relatively. The forward and backward activity factors cancongured independently!
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IUB bandwidth admission desicion For a new user, the following requirements apply:
Total bandwidth allocated to the users on the path + required bandwidth for the new user < total bandwidth
configured for the path – bandwidth reserved for handover.
Total bandwidth allocated to the users on the physical link + required bandwidth for the new user < total
bandwidth of the physical link – bandwidth reserved for handover.
For a handover user, the following requirements apply:
Total bandwidth allocated to the users on the path + required bandwidth for the handover user < total bandwidth
configured for the path.
Total bandwidth allocated to the users on the physical link + required bandwidth for the handover user < total
bandwidth of the physical link.
For a rate upsizing user, the following requirements apply:
Total bandwidth allocated to the users on the path + required bandwidth for the rate upsizing user < total
bandwidth configured for the path – congestion threshold.
Total bandwidth allocated to the users on the physical link + required bandwidth for the rate upsizing user < total
bandwidth of the physical link – congestion threshold.
Congestion clear bandwith
Congestion bandwidth
Handover resovered bandwidth
Total bandwidth
High
Low
Path/resource group/phycial port
Threshold
The forward and backward bandwidththresholds are set respectively. Also,
different level bandwidth threshold can be
set separately.
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IUB bandwidth admission procedure
Primary and secondary paths are used in admission control. According to the mapping between traffic
types and transmission resources, the RNC first selects the primary path for admission. If the
admission on the primary path fails, then the admission on the secondary path is performed.
The user tries to be admitted to available bandwidth 1 of the primary path, as shown in the Figure. The
procedure is as following:
If the admission on the primary path is successful, the user is carried on the primary path.
If the admission on the primary path fails, the user tries to be admitted to available bandwidth 2 of the secondary
path.
If the admission on the secondary path is successful, the user is carried on the secondary path. If not, the
bandwidth admission request of the user is rejected.
Admission decision for a new user :
Available bandwidth 1 = total bandwidth of the primary path - used bandwidth - handover reserved bandwidth
Available bandwidth 2 = total bandwidth of the secondary path - used bandwidth - handover reserved bandwidth
For a new user
admission,
bandwidth for
handover users
is reseved
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IUB bandwidth admission procedure
Admission procedure for a handover user
Available bandwidth 1 = total bandwidth of the primary path - used bandwidth
Available bandwidth 2 = total bandwidth of the secondary path - used bandwidth
Admission procedure for a rate upsizing user
Available bandwidth 1 = total bandwidth of the primary path - used bandwidth - congestion reserved bandwidth
Available bandwidth 2 = total bandwidth of the secondary path - used bandwidth - congestion reserved bandwidth
For handover users
admission,allocation of the
bandwidth is 100%!
For rate upsizing
users admission,
congestion reserved
bandwidth is reserved
Note: Therefor, the serivce priority is: handover users > new users> rate upsizing users
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CAC Based on the Number of HSPA Users
CAC of HSDPA Users
When a new HSDPA service attempts to access the network, the algorithm admits the
service if the following conditions are met:
The number of HSDPA users in the cell does not exceed the maximum value specified by
MaxHsdpaUserNum.
The number of HSDPA users in the NodeB does not exceed the maximum value specified by
NodeB HsdpaMaxUserNum.
Otherwise, the algorithm rejects the service request.
CAC of HSUPA Users
When a new HSUPA service attempts to access the network, the algorithm admits the
service if the following conditions are met:
The number of the HSUPA users in the cell does not exceed the maximum value specified by
MaxHsupaUserNum.
The number of the HSUPA users in the NodeB does not exceed the maximum value specified by
NodeB HsupaMaxUserNum.
Otherwise, the algorithm rejects the service request.
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Contents
Perface Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm
Intelligent Access Control Algorithm
Intelligence Access Control Overview
IAC During RRC Setup Stage
IAC During RAB Setup Stage
IAC for Emergency Calls
Load Reshuffling Algorithm
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
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Intelligence Access Control Algorithm
IAC algorithm is used to increase the access success ratio with the currentQoS guaranteed through Rate Negotiation, Directed Retry Decision(DRD),
Preemption, Queuing and BE service Low-Rate Access.
RAB Rate
Negotiation
RAB Directed
Retry Decision
RAB
preemption
RAB
queuing
Low-RateAccess
RRC IAC
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Intelligence Access Control Overview
Admission
algorithmFails or not supported
Fails
Target cell
selected
Fails
Succeeds
RAB processing
RRC connection processing
Rate
negotiation
PS domain:
maximum rate
PS and CS
domains:
initial rate
Power
admission
Code admission
Iub resource
admission
Credit admission
FailsRRCconnection
request
Admissionalgorithm
DRD Redirection
RAB setup request
HSPA user
number admission
Succeeds
PS domain:GBR of PS
RT service
Service requestaccepted
Preemption
Queuing
Fails or not supported
Succeeds
Succeeds
Succeeds
Fails
NoYes
Service
steering DRD
Load balancing
DRD
DRD
algorithm
Is there any
cell not tried?
Service request
denied
Target Rate
Negotiation
Service-based RRC
redirection
Lead UE toanother cell
Access from another cell
Access from
current cell
Succeeds
Low-rateaccess
Fails or not supported
Succeeds
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IAC procedure supported by different services
ServiceType Low-Rate
Access
Rate Negotiation Preemption Queuing DRD
MB
R
Nego
tiatio
n
GBR
Nego
tiatio
n
Initial
Rate
Negotiat
ion
Target
Rate
Negotia
tion
Inter-
Freque
ncy
Inte
r-
RA
T
DCH √ √ √ √ √ √ √ √ √
HSUPA - √ √ √ √ √ √ √ –
HSDPA - √ √ – – √ √ √ –
Note: MBR stands for maximum bit rate
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IAC During RRC Setup Stage
RRC Direct
Retry
Decision
RRCRedirection
for Service
Steering
IAC duringRRC
SetupRRC
Redirection
After DRD
Failure
In the RRC connection setup stage, there arethree actions for intelligence access control
algorithm:
During the RRC connection setup, the
RNC implements service steering
between inter-frequency or inter-RAT
cells according to the cause of RRCconnection setup.
If the RRC CAC fails, RNC selects
inter-frequency, but intra-band blind
neighboring cells to do RRC DRD;
If RRC DRD fails, select inter-
freq/inter-RAT blind neighboring cellsto do redirection action;
For emergency call, different strategy is used for the RRC setup IAC !
RRC R di ti f S i St i
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RRC Redirection for Service Steering
During the RRC connection setup, the RNC implements service steering between inter-
frequency or inter-RAT cells according to the cause of RRC connection setup. The procedure
of RRC redirection for service steering is as follows:
If the switch of RRC direction for service steering (RedirSwitch) is set to
ONLY_TO_INTER_FREQUENCY or ONLY_TO_INTER_RAT , based on the cell load and the
redirection factors, RNC decides whether to perform RRC redirection for service
steering acconding to the cause of the service requested by UE and the capability of
UE. If the switch is off or the RNC fails to determine the service type, the RNChandles the RRC connection setup request of the UE in the current cell.
Based on the setting of Redirection Switch, the RNC takes the corresponding actions:
If RedirSwitch is set to ONLY_TO_INTER_FREQUENCY , the RNC sends an RRC
CONNECTION REJECT message to the UE, redirecting the UE to the destination
frequency carried in the message. .
If RedirSwitch is set to ONLY_TO_INTER_RAT , the RNC sends an RRC CONNECTION
REJECT message to the UE. The message carries the information about inter-RAT
neighboring cells.
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RRC Redirection for load balancing
In addition, the RNC considers the load of the cell for access and the redirection factors
to control the degree of load balancing. If the cell is normal, the RNC generates a random number between 0 and 1 and
compares it with the corresponding unconditional redirection factor. If the random
number is smaller than this factor, the RNC performs the redirection action
according to the setting of Redirection Switch . Otherwise, the RNC handles the
RRC connection setup request of the UE in the current cell.
If the cell is in the basic congestion or overload state, the RNC generates a random
number between 0 and 1 and compares it with the corresponding LDR-triggered
redirection factor. If the random number is smaller than this factor, the RNC
performs the redirection action according to the setting of Redirection Switch .
Otherwise, the RNC handles the RRC connection setup request of the UE in the
current cell.
Note: The RRC redirection action needs inter-frequency or inter-RAT blind neighboring cells. If
this condision don’t meet, the RRC redirection will not happened.
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RRC DRD after CAC failure
If the RRC setup is CAC failure as the resource insufficient, and the RRC DRD
switch is open, the following procedure will be implemented: The RNC selects intra-band inter-frequency neighboring cells of the current
cell. These neighboring cells are suitable for blind handovers.
The RNC generates a list of candidate DRD-supportive inter-frequency cells
according to the singal quality.
The RNC selects a target cell from the candidate cells for UE access. If the
candidate cell list contains more than one cell, the UE tries a cell randomly. If the admission is successful, the RNC initiates an RRC DRD procedure.
If the admission to a cell fails, the UE tries admission to another cell in the
candidate cell list. If all the admission attempts fail, the RNC makes an RRC
redirection decision.
If the candidate cell list does not contain any cell, the RRC DRD fails. The
RNC performs the next step, that is, RRC redirection.
Note: If the RRC DRD switch is closed, the RRC redirection action based on RRC CAC
failure will be performed.
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RRC Redirection After DRD Failure
The RNC performs the following steps when the RRC DRD swtich is off for the RRC DRD
procedure fails:
The RNC selects all intra-band inter-frequency neighboring cells of the current cell as the candidate
cells.
The RNC selects a cell from candidate cells. The candidate cells are the cells selected in step 1 but
exclude the cells that have carried out inter-frequency RRC DRD attempts.
If more than one candidate cell is available, the RNC selects a cell randomly and redirects the UE to
the cell.
If no candidate cell is available,
If the switch of RRC redirection after DRD failure is set to Only_To_Inter_Frequency, the RRC connection
setup fails.
If the switch of RRC redirection after DRD failure is set to Allowed_To_Inter_RAT , then:
If a neighboring GSM cell is configured, the RNC redirects the UE to that GSM cell.
If no neighboring GSM cell is configured, the RRC connection setup fails
Note: If the RRC recirection switch is OFF, then the RRC Connection procedure stage fails.
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IAC During RAB Setup Stage
During the RAB setup stage, several IAC actions will be attempted orderly to
increase the access success radio: RAB Rate Negotiation
RAB Direct Retry Decision(DRD)
RAB Preemption
RAB Queuing
RAB Low-Rate Access for BE service
RAB IAC actions work as following:
RAB Rate
Negotiation
RAB Direct
Retry
Decision
RAB
Preemption
RAB
QueuingLow-Rate
Access
Service Access
Failure
Service access success
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RAB Rate Negotiation
Maximum rate negotiation
When setting up, modifying, or admitting a PS service, and the 'Alternative RAB Parameter Values' of IE is present in theRANAP RAB ASSIGNMENT REQUEST or the RELOCATION REQUEST message, the RNC and the CN negotiate the rate
according to the UE capability to obtain the maximum expected rate while ensuring a proper QoS.
GBR rate negotiation
During the setup, modification, or handover of real-time PS services, if the RAB assignment message includes multiple
alternative guaranteed bit rates, the RNC selects the smallest one as the negotiated guaranteed rate and responds to the CN.
Initial rate negotiationFor a non-real-time service in the PS domain, the RNC selects an initial rate to allocate bandwidth for the service before
the cell resource request.The negotiation is based on the cell load information, which includes:
Uplink and downlink radio bearer status of the cell
Minimum spreading factor supported
HSPA capability
Target rate negotiation
For a non-real-time service in the PS domain, if cell resource admission fails, the RNC chooses a target rate to allocate
bandwidth for the service based on cell resource in following cases:
Service setup
Soft handover
DCCC rate upsizing
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D t il d i f ti f l d b l DRD l ith
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Detailed information for load balance DRD algorithm
Algorithm 1
The load balancing DRD is performed according to the cell measurement values about the DL non-HSDPA
power and DL HS-DSCH required power. For DCH service, the RNC sets up the service on a carrier with a light load of non-HSDPA power to achieve load
balancing among the cells on the different frequencies.
For HSDPA service, the RNC sets up the service on a carrier with a light load of HS-DSCH required power to
achieve load balancing among the cells on different frequencies.
Algorithm 2
The load balancing DRD is performed according to the DCH Equivalent Number of Users (ENU) and
HSDPA user number.
For DCH service, the RNC sets up the service on a carrier with a light load of DCH ENU to achieve load balancing
among the cells on different frequencies.
For HSDPA service, the RNC sets up the service on a carrier with a light load of HSDPA user to achieve load
balancing among the cells on different frequencies.
The effect of the algorithm as shown in the previous page:
Cell B has a lighter load of non-HSDPA power than Cell A. If the UE requests a DCH service in Cell A, preferably,the RNC selects Cell B for the UE to access.
Cell A has the lighter load of HS-DSCH required power than Cell B .If the UE requests an HSDPA service in Cell B,
preferably, the RNC selects Cell A for the UE to access.
Note: The calculation of the DCH Equivalent Number of Users is the same as rules of call admission control part.
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Inter-Frequency DRD due to CAC failure
The precondition is that it is covered by multiple frequencies when the UE
requests a service in an area.The RNC selects a suitable cell in candidate cell. The
CAC algorithm makes an admission decision based on the resource status of the cell.
If the admission attempt is successful, the RNC initiates an inter-frequency blind
handover to the cell.
If the admission attempt fails, the RNC removes the cell from the candidate cells and
then checks whether all candidate cells are tried.
If there is any candidate cell not tried, the algorithm goes back to try this cell.
If all candidate cells haven been tried, then:
• If the service request is an HSPA one, the HSPA request falls back to a DCH one. Then, the
algorithm goes back to step 1 to retry admission based on R99 service priorities.
• If the service request is a DCH one, the RNC initiates an inter-RAT DRD.
Note: If there is no inter-frequency neighboring cells exist or the inter-frequency handover procedure is failure for all the attempts, the inter-RAT DRD may be happened.
I RAT DRD d CAC f il
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Inter-RAT DRD due to CAC failure
When all admission attempts for inter-frequency DRD during RAB processing fail, theRNC determines whether to initiate an inter-RAT DRD.
The inter-RAT DRD procedure is as follows:
If the current cell is configured with any neighboring GSM cell suitable for blind handover,
and the RNC performs this action.
The RNC generates a list of candidate DRD-supportive inter-RAT cells that fulfill the
singal quality requirement.
The service request then tries admission to a target GSM cell in order of blind handover
priority.
Note: If there is no suitable handover cells exist or the inter-RAT handover procedure is failurefor all the attempts, the service request undergoes preemption and queuing.
RAB preemption
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RAB preemption
Why we use preemption function
Preemption guarantees the success in the access of a higher-priority user by forcibly
releasing the resources of a lower-priority user. We support the preemption scenarios in
following cases:
Setup or modification of a service
Hard handover or SRNS relocation
UE state transits from CELL_FACH to CELL_DCH
Preemption preconditions
RNC performs preemption if the following conditions are met:
New serivce have the preemption capacity
The destination service can be preempted
User priority are satisfied.
USERUSER
1 2 3 N
USERUSERS USER
K
END
High LowUser Integration priority
VIP USER
Preemption of different service on different resources
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Preemption of different service on different resources
Service Resource Service That can Be Preempted
R99 HSUPA HSDPA R99 + HSPA Combined
R99 service Code √ - - √
Power √ - √ √
CE √ √ - √
Iub bandwidth √ √ √ √
HSDPA service Code - - - -
Power √ - √ √
CE - - - - Iub bandwidth √ - √ √
Number of users - - √ √
HSUPA service Code - - - -
Power - √ - -
CE √ √ - √
Iub bandwidth √ √ - √
Number of users - √ - √
Note: The preemption function is controlled by corresponding algorithm switch on the RNC.
RAB Queuing
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RAB Queuing
After the admission of a service fails, the service request is put into a specific queue
to increase the access success radio. Admission attempts for the service request are made
periodically during a defined period of time.
USER
1 2 3 K N
USERUSER USERS USER
NEW
USER
END
Heartbeat
timer
Queue
When timer expires, select the
request with the highest
integrate priority for an attempt
of resource allocation.
Note:
RNC performs queuing when the service has the queue capacity.
The Preemption and queuing capacity is difined in RANAP RAB ASSIGNMENT
REQEST message on the IU interface.
Detailed information for RAB Queuing
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Detailed information for RAB Queuing
When a new queuing request is received, the queuing algorithm will do some decision:
If the queue is not full, then the queqing algorithm will put this request into the quque and start the
heartbeat timer if it is not started.
If the queue is full, then the queuing algorithm check out whether there are have requests whose
intergate priorities are lower than that of new request
• If yes, then preemption occurs in the queue,that is lower request are took out and
rejected,New request are put into the queuing.
• If no,then the queing algorithm rejects the new request directly.
After the heartbeat timer(500ms) expires, the queuing algorithm proceeds as follows:
Rejects the request which the actual waiting time of is longer than the value of the Max queuing
time length parameter.
Selects the request with the highest integrate priority for an attempt of resource allocation.
• If the attempt is successful, the heartbeat timer is restarted for the next processing upon
expiry of this timer.
• If the attempt fails, the queuing algorithm puts the service request back into the queue with
the time stamp unchanged for the next attempt.
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Low-Rate Access of the PS BE Service
If a preemption or queuing failure, the PS BE service can access the target cell at a low
rate to increase the access success rate. Low-rate access means access from the DCH at 0kbit/s, FACH, or enhanced FACH (E-FACH).
Low-rate access is used in the following scenarios:
RAB setup
Hard handover or relocation
After an appropriate access action is determined, the service attempts to access the
network
If the action of access from the DCH at 0 kbit/s is determined, the service attempts to access
the network at 0 kbit/s for traffic and at the normal rate for signaling.
If the action of access from the FACH/E-FACH is determined, the service attempts to access
the network from the FACH/E-FACH.
If the access attempt fails, this service is rejected.
For the service that accesses the network at 0 kbit/s, the rate up timer is started after the
service rate fails to increase for the first time. If the rate fails to increase even when the timer
expires, the service is released, and the connection is also released for a single service.
L t ti i diff t i
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Low-rate access actions in different scenarios
Scenario Scenario Description FACH/E_FACH DCH at 0 kbit/s
RAB setup
The RRC connection is set up on the FACH or E-FACH. √ ×
The RRC connection is set up on the DCH. × √
The RRC connection is set up on the HSPA channel. × √
Combined
services
Hard handover or relocation is performed for the CS+PS
combined services.× √ (Note 1)
Hard handover or relocation is performed for the PS+PS
combined services.× √
The CS service is set up, and a new PS service is to be set up. × √
The existing PS service is set up on the FACH/E-FACH, and a
new PS service is to be set up.√ ×
The existing PS service is set up on the DCH, and a new PS
service is to be set up.× √
The existing PS service is set up on the HSPA channel, and a
new PS service is to be set up.
× √ (Note 2)
The PS service is set up, and a new CS service is to be set up. × ×
Note:
Note 1: In this scenario, only the PS service can be admitted at 0 kbit/s.
Note 2: In this scenario, the new PS service can be admitted at 0 kbit/s, and the existing service are not affected.
IAC f E C ll
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IAC for Emergency Calls (RRC setup stage)
To guarantee successful access of emergency calls, the RNC takes special measures for
emergency calls.
Resource admission in RRC setup stage
For power resource, the emergency call is admitted regardless of whether the CAC algorithm is
enabled or not..
For hard resources (that is, code, Iub, CE), preemption will always happened due to admission
failure.
RRC connection
setup request
Admission
algorithmPreemption DRD Redirection
RAB process
Fails
Succeeds
Fails Fails
Succeeds Succeeds
Note: To guarantee a successful admission of an emergency call, the RNC does not
perform RRC redirection for service steering.
IAC f E C ll
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IAC for Emergency Calls (RAB setup stage)
Resource admission in RAB setup stage
For power resource, when the admission switch for emergency call is enabled, power-based
admission fails if the system is in the overload congestion state. Otherwise, the admission
succeeds.
For hard resources (that is, code, Iub, and CE), the resource-based admission is successful if the
current remaining resources are sufficient for the request. Otherwise, the admission fails.
Preemption procedure The emergency calls that trigger preemption have the highest priority, the preempted users have
the lowest priority.
preemption is performed regardless of whether the preempt algorithm is enabled or not.
The range of users that can be preempted is specified by the specific switch, that is whether the
emergecy call can preempt the users which have preemption-prohibited attribute.
Note: The emergency calls can only preempt the non-emergency users.
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Contents
Perface
Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm
Intelligent Access Control Algorithm
Load Reshuffling Algorithm
Load Reshuffling Algorithm Overview
Load reshuffling triggering
Load reshuffling actions
Overload Control Algorithm
Dynamic Cell Shutdown Algorithm
L d R h ffli Al ith O i
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Load Reshuffling Algorithm Overview
When the usage of cell resource exceeds the basic congestion triggering threshold, the
cell enters the basic congestion state. In this case, LDR is required to reduce the cell loadand increase the access success ratio.
Four resources can trigger the basic congestion of the cell:
power resource,
code resource,
Iub resource,
NodeB credit resource.
Load reshuffling algorithm procedure has three stages, that is:
Basic Congestion Triggering
LDR Procedure
LDR Actions
Tiggering style
For power resource, the RNC performs periodic measurement and checks whether the
cells are congested.
For code, Iub, and NodeB credit resources, event-triggered congestion applies, that is,
the RNC checks whether the cells are congested when resource usage changes.
LDR Triggering for power resource
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LDR Triggering for power resource
For an R99 cell:
If the current UL/DL load of the R99 cell is higher than or equal to the basic congestion trigger
threshold in UL/DL for 1000ms, the cell works in the basic congestion state. If the current UL/DL load of the R99 cell is lower than the UL/DL LDR Release threshold for
1000ms, the cell returns to the normal state.
For an HSPA cell:
In the uplink, the object to be compared with the associated threshold for decision is the
uncontrollable load.
In the downlink, the object to be compared with the associated threshold for decision is the sum
of the non-HSDPA power and the Power Requirement for GBR (GBP).
LDR Thresholds for power resource
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LDR Thresholds for power resource
LDR trigger
Other services
AMR&non-AMR
Handover access
Total power
OLC
High
Low
Cell power load
Threshold
LDR state
Normal stateLDR release
Threshold Name Uplink Downlink
Overload trigger threshold 95 95
Overload release threshold 85 85
Total power threshold 83 90
Handover access threshold 80 85
AMR access threshold 75 80 Non-AMR access threshold 75 80
Other services access threshold 60 75
Load reshuffling trigger threshold 55 70
Load reshuffling release threshold 45 60
When the cell enters the basic
congestion state, the maximum
target rate is GBR for BE RAB.Therate upsizing exceed GBR is
forbidden!
They are baseline values of
coresponding threshold in huawei
RNC.These valuses are notrecommended modified in live
network, but can be modified in the
testbed to help testing easier when
verify the load control algorithms.
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LDR Triggering for Code Resource
Congestion control algorithm based on code resource can be enabled through the
specific parameter on RNC Local Maintenance Terminal.
If the SF corresponding to the current remaining code of the cell is larger than Cell
LDR SF reserved threshold, code congestion is triggered.
When the code resource congestion triggered, that means the spread code resourceis insufficient, and the access success raido maybe lower than the normal state.
Note: Only the downlink spread code may be insufficient and triggerr the code resource load
reshuffling, the code in uplink always sufficient and never trigger the LDR state.
LDR T i i f N d B C dit R
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LDR Triggering for Node B Credit Resource
The basic congestion for NodeB credit is of the following types:
Type A: Basic congestion at local cell level
If the cell UL/DL current remaining SF (mapped to credit resource) is higher than UL LDR
Credit SF reserved threshold/DL LDR Credit SF reserved threshold, credit congestion at cell
level is triggered.
Type B: Basic congestion at local cell group level (if any)
The same as the basic congestion at Node B level.
Type C: Basic congestion at NodeB level
If the cell group or NodeB UL/DL current remaining SF (mapped to credit resource ) is higher
than UL LDR Credit SF reserved threshold/DL LDR Credit SF reserved threshold, credit
congestion at cell group or NodeB level is triggered.
Note: When RNC performs Load reshuffling actions for the CE reource, the range of UEs to be
sorted by priority is different from other resources, all the UEs in the normal-state cells that belong to the
cell group or NodeB will be sorted based on the integrated priority.
LDR Triggering for Iub Bandwidth Resource
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LDR Triggering for Iub Bandwidth Resource
Congestion detection can be triggered in any of the following conditions:
Bandwidth adjustment because of resource allocation, modification, or release Change in the configured bandwidth or the congestion threshold
Fault in the physical link
Assume that the forward parameters of a port for congestion detection are
defined as follows:
Configured bandwidth: AVE
Forward congestion threshold: CON
Forward congestion clear threshold: CLEAR (Note that CLEAR is greater than CON.)
Used bandwidth: USED
Then, the mechanism of congestion detection on the port is as follows:
Congestion occurs on the port when CON + USED ≥ AVE.
Congestion disappears from the port when CLEAR + USED < AVE.
i i f i
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LDR Triggering for Iub Bandwidth Resource
The congestion detection for a path or a resource group is similar to that for a port.
Generally, congestion thresholds need to be set for only ports or resource groups. If
different types of AAL2 paths or IP paths require different congestion thresholds, the
associated parameters need to be set for the paths as required.
If ATM LPs or IP LPs are configured, congestion control is also applicable to the LPs.
The congestion detection mechanism for the LPs is the same as that for resource
groups.
Load Reshuffling Actions
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Load Reshuffling Actions
Procedure: As showed in the illustration, if the inter-frequencyhandover action succeeds, the determination of whether the systemis congested continues. If the system is still congested, the inter-frequency load handover is initiated again.
If the handover fails, code reshuffling is performed:If the code reshuffling succeeds, the determination of whether thesystem is congested continues. If the system is still congested, thecode reshuffling is initiated first.
If the code reshuffling fails, the next action, that is, BE ratereduction, is taken.
… …
Code reshuffling
Inter-frequency load handover
BE service rate reduction
Uncontrolable realtime
Qos renegotiation
AMR rate reduction
Inter-system load handover
in the CS domain
Inter-system load handover
in the PS domain
MBMS power reduction
L o a
d R e s u
f f l i n g
A c
t i o n s
Actions: As the illustration, the sequence of the LDR actions isfixed to Inter-freq load handover, code reshuffling, BE rate reduction,
Uncontrolable realtime Qos renegotiation, AMR rate reduction,
Inter-system handover in CS domain, Inter-system handover in PS
domain, and MBMS power reduction.
Occasion: When the cell is in basic congestion state, the RNCtakes one of the following actions in each period until the congestionis resolved
Order: The sequence of the LDR actions can be changed throughthe ADD CELLLDR command, and the waiting timer for LDR period is defined by the LDR period timer length parameter through
the SET LDCPERIOD command.
LDR actions performed for different resources
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LDR actions performed for different resources
ResourceUL/
DL
Channel
LDR Actions
Inter-
Frequency
Load
Handover
BE Rate
Reduction
Inter-RAT
Handover inCS Domain
Inter-RAT
Handover inPS Domain
AMR Rate
Reduction
Iu QoS
Renegotiation
Code
Reshuffling
MBMS
PowerReduction
Power
UL
DCH √ √ √ √ √ √
HSUPA √ √
DL
DCH √ √ √ √ √* √
HSDPA √ √ FACH
(MBMS) √*
Iub
UL
DCH √ √ √
HSUPA √
DL
DCH √ √ √ HSDPA √ FACH
(MBMS)
LDR actions performed for different resources
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LDR actions performed for different resources
ResourceUL/
DLChannel
LDR Actions
Inter-
Frequency
LoadHandover
BE Rate
Reduction
Inter-RAT
Handover in
CS Domain
Inter-RAT
Handover in
PS Domain
AMR Rate
Reduction
Iu QoS
Renegotiatio
n
Code
Reshuffling
MBMS
Power
Reduction
code
– –
DL
DCH √ √ √
HSDPA
FACH
(MBMS)
credit
UL
DCH √ √ √ √
HSUPA √ √
DL
DCH √ √ √ √
HSDPA
FACH
(MBMS)
Note: Whether the gold users perform the LDR actions is controled by specific switch on RNC
Loal Maintenance Terminal.
Action 1: Inter Frequency Load Handover
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Action 1: Inter-Frequency Load Handover
Inter-FrequencyLoad Handoveraction performed
Power resource LDR…
The UL/DL HO load space threshold for the target cell
must be satified
Target Cell condition
… The neighbouring cell must be the inter-frequency blind
handover cell,and the measured signal quality can meet
…
After actions performed, all of the resources in the target
cell do not trigger basic congestion
Service condition…
For the selected UE, its UL/DL current bandwidth has to be
less than the UL/DL HO maximum bandwidth
…
The LDR algorithm selects one UE to perform the actions
according to the user integrate priority.
Code resource LDR…
The minimum SF of target cell mustn’t greater then thecurrent cell
… The difference of code occupy rate must meet the
InterFreq HO code used ratio space threshold
If the conditions are not
meet or the action fails, the
algorithm will go to next
action desicion
All the conditons must
be satified, then the
action will be
performed
Action 2: BE Rate Reduction
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Baise principle
BE Rate Reduction action of
basic congestion algorithm
Service
condition
•This action is used for DCH
RAB and HSUPARAB .Only BE service will
be considered.
•The selected RAB bit ratemust greater than GBR.
Rate downsizing Rate recovery
•If the selected RAB is a DCH RAB, only3-rate downsizing applies.
•If the current rate is MBR, the rate is
downsized to Uplink mid bit rate threshold.•If the current rate is higher than GBR butlower than MBR, the rate is downsized to
GBR.
•In the LDR state, the rate upsizingtarget rate is GBR.
•After basic congestion is cleared, the
rate upsizing target rate is MBR rate.•If the rate upsizing will trigger the
basic congestion,the action should not
be happened.
•User selection based on theintegrate priority, the lowest RAB
will be processed first .
•The number of RABs to select isdetermined by the UL/DL LDR-BE
rate reduction RAB number
parameter .
Action 2: BE Rate ReductionIn the same environment, different rates consume different resource. The higher the rate is, the more
resource will be needed. Therefore, the load can be reduced by bandwidth reconfiguration. The BE ratereduction action is based on DCCC algorithm. When admission control of Power/NodeB Credit is disabled,it is not recommended that the BE Rate Reduction be configured as an LDR action in order to avoid ping-
pong effect.
For HSUPA service, this action is
just used for CE resource LDR, and
the rate variety depends on HSUPA
UpLink rate adjust set parameter
The reconfiguration is completed
as indicated by the RB
RECONFIGURATION message
on the Uu interface and through
the RL RECONFIGURATION
message on the Iub interface.
Note: If the conditions are not meet or action fail, the algorithm will go to next action decision.
Action 3:
Uncontrolled Real-Time QoS Renegotiation
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Based on this action, the RNC can adjust the rate of real-time services to reduce theload of the current cell.
Q g
Baise Principle
Service
Pondition
Uncontrolled Real-
Time QoS
Renegotiation
Renegotiation
Procedure
The target rate is the GBR rate which is indicated on
Iu interface when the serivce setup.
The RNC initiates the RAB renegotiation procedure
through the RAB MODIFICATION REQUEST
message on the Iu interface.
The Core Network sends the RAB ASSIGNMENT
REQUEST message to the RNC for RAB parameterreconfiguration.
• This action is just used forDCH RAB.
• Only the real-time services inthe PS domain will be
considered. For example, the
streaming service.
•User selection based on theintegrate priority, the lowest
RAB will be processed first .
•The number of RABs toselect is determined by the
UL/DL LDR un-ctrl RT Qos
re-nego RAB num parameter .
Note: If the conditions are not meet or actions fails, the algorithm will go to next action decision.
This action is not recommended
to be configured when there are
no steaming traffic calss
subscribed in live network.
Action 4: Inter-RAT Handover in the CS Domain
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According to the different “service-handover” IE in the RAB ASSIGNMENT REQ message onthe IU interface,this action is divided into two types: Inter-RAT Should Be Load Handover in the CS Domain
Inter-RAT Should Not Be Load Handover in the CS Domain
The two actions have completely similar parameters and procedures, therefore, we just introducethe “Inter - RAT Should Be Load Handover in the CS Domain” action here as an example.
Service
condition
… −The UE can support inter-RAT compress mode.
… The AMR DCH service in the CS domain, which the
“service-handover” IE is set to "handover to GSM should be performed" in RAB ASSIGNMENT REQ message.
…
The algorithm selects RAB to perform this action according to
integrate priority. the lowest RAB will be selected first. Basic
principle
… The number of UEs which are selected is controled by the UL/DL
CS should be ho user number parameter.
Environment
condition
…
The CS inter-rat handover algorithm switch and the CS inter-
rat handover algorithm parameter are both enabled.
… The GSM neighbouring cells are configured properly.
Note: If the conditions are not meet or actions fails, the algorithm will go to next action decision.
Inter-RAT
Handover in the
CS Domain
performed
Action 5: Inter-RAT Handover in the PS Domain
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The action procedure of I nter -RAT H andover in the PS Domain is similar to that of Inter- RAT H andover in the CS Domain .
Action 5: Inter RAT Handover in the PS Domain
Actions 6: AMR Rate Reduction
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Actions 6: AMR Rate Reduction
In the WCDMA system, voice services work in eight AMR modes. Each mode has its own rate.
Therefore, mode control is functionally equal to rate control.
The LDR algorithm operates in the downlink as follows:
In the downlink direction
Based on the integrate priority, the LDR sorts the RABs in descending order. RABs with AMR
services (conversational) and with the bit rate higher than the GBR are selected. The number of
RABs to select is determined by the DL LDR-AMR rate reduction RAB number parameter.
The RNC sends the Rate Control request message through the IuUP to the CN to adjust the
AMR rate to the GBR.
If the RNC cannot find an appropriate RAB for the AMR rate reduction, the action fails. The
LDR takes the next action.
In the Uplink direction
The only difference from downlink is on the step 2: The RNC sends the TFC CONTROL command to
the UE to adjust the AMR rate to the GBR..
Note: This action is just suitable for CS AMR service which is canrried on the DCH.
Action 7 Code Reshuffling
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Principle
When the cell is in basic congestion for shortage of code resources, sufficient code resources can be
reserved for subsequent service access through code reshuffling. Code subtree adjustment refers to the
switching of users from one code subtree to another. It is used for code tree defragmentation, so as to free
smaller codes first.
The algorithm operates as follows:
Step 1 : Initialize the SF_Cur of the root node of subtrees to Cell LDR SF reserved threshold.
Step 2 : Traverse all the subtrees with this SF_Cur at the root node. Leaving the subtrees
occupied by common channels and HSDPA channels out of account, take the subtrees in which
the number of users is not larger than the value of the Max user number of code adjust parameter
as candidates for code reshuffling.
Step 3: Select a subtree from the candidates to perform the action
Step 4: Treat each user in the subtree as a new user and allocate code resources to each user.
Step 5: Initiate the reconfiguration procedure for each user in the subtree and reconfigure thechannel codes of the users to the newly allocated code resources.
Action 7:Code Reshuffling
Note: If no such candidate is available in step 2, subtree selection fails. This procedure ends.
Code Reshuffling Procedure
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Code Reshuffling Procedure
The reconfiguration procedure on the UU interface is implemented through thePHYSICAL CHANNEL RECONFIGURATION message and that on the Iubinterface through the RL RECONFIGURATION message.
In the Step 3 in previous page, subtree select principle according to the setting
of the LDR code priority indicator parameter:
If this parameter is set to TRUE, select the subtree with the largest code number from thecandidates.
If this parameter is set to FALSE, select the subtree with the smallest number of users from
the candidates. In the case that multiple subtrees have the same number of users, select the
subtree with the largest code number.
The following figures show an example of code reshuffling. In this example, Cell
LDR SF reserved threshold is set to SF8 and Max user number of code adjust is
set to 1.
Action 8: MBMS Power Reduction
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Action 8: MBMS Power Reduction
The downlink power load can be reduced by lowering power on MBMS traffic
channels.
The algorithm operates as follows:
Based on the integrated priority, the algorithm sorts the RABs in descending order.
The algorithm selects a RAB with the lowest integrated priority and with the
current power higher than the minimum transmit power of the corresponding
MTCH. That is, it selects a RAB of which the ARP value is higher than
MbmsDecPowerRabThd.
The algorithm triggers a reconfiguration procedure to set the power to the
minimum transmit power of the FACH onto which the MTCH is mapped.
The reconfiguration procedure on the Iub interface is implemented through the
COMMON TRANSPORT CHANNEL RECONFIGURATION REQUEST
message.
C t t
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Contents
Perface
Load Control Algorithm Overview
Auto-Adaptive Background Noise Algorithm
Potential User Control Algorithm
Call Admission Control Algorithm