wcdma load control workshop.ppt
TRANSCRIPT
Apr. 2006
Node B Products of Huawei
May 2008
WCDMA Load Control
HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com
HUAWEI TECHNOLOGIES Co., Ltd. HUAWEI Confidential Page 2
Overview
PUC
CAC
IAC
LDR
OLC
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Load Control exists in all phases
Load Control is used to keep system stable, maximize system capacity while ensuring the coverage and QoS.
Different load control algorithms according to different phases provided:- Before UE access: Potential User Control (PUC)- During UE access: Call Admission Check (CAC) and Intelligent Access Control (IAC)- After UE access: Load Reshuffling (LDR), and Overload Control (OLC)
3. After UE access2. During UE access1. Before UE access
Time
• LDRCACPUC• OLC
•• IAC
PUC: Potential User Control CAC: Call Admission ControlIAC: Intelligent Admission Control LDR: Load ReshufflingOLC: Overload Control
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Load control features
PUC
The function of PUC is to balance traffic load among inter-frequency cells. By modifying
cell selection and reselection parameters and broadcasting them through system
information, PUC leads UEs to cells with light load. The UEs may be in idle mode,
CELL_FACH state, CELL_PCH state, or URA_PCH state.
CAC
The function of CAC is to decide on resource requests from UEs, such as access,
reconfiguration, and handover requests, according to the resource status of the cell.
IAC
The function of IAC is to increase the access success rate with the current QoS assured
through rate negotiation, queuing, preemption, and Direct Retry Decision (DRD).
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Load control features
LDR
The function of LDR is to reduce the load of a cell when the available resources of the
cell reach the specified alarm threshold. The purpose of LDR is to increase the access
success rate in the following ways:
Inter-frequency load handover
Code reshuffling
BE service rate reduction
AMR voice service rate reduction
Uncontrolled realtime traffic QoS renegotiation
CS inter-RAT load handover
PS inter-RAT load handover
OLC
The function of OLC is to reduce the cell load rapidly by restricting the Transport Format
(TF) of the BE service or releasing UEs when the cell is overloaded. The purpose of OLC
is to ensure the stability of the system and the QoS of most UEs.
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Load Control for different cell load level
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Thresholds and actions of the load control algorithms
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RAB integrate priority
If the value of the parameter is set to Traffic Class, the integrate
priority abides by the following rules:
Classes of services: conversational -> streaming -> interactive ->
background
Services of the same class: priority based on Allocation/Retention Priority
(ARP) values
Only for the interactive service of the same ARP value: priority based on
THP
Services of the same class and priority: HSDPA or DCH service preferred
on the basis of the value of the Indicator of Carrier Type Priority
parameter
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RAB integrate priority
If the value of the parameter is set to ARP, the integrate priority
abides by the following rules:
ARP1 -> ARP2 -> ARP3 … -> ARP14
Same ARP value: conversational -> streaming -> interactive ->
background
Only for the interactive service of the same ARP: priority based on THP
Services of the same ARP, class and THP (only for interactive service ):
HSDPA or DCH service preferred on the basis of the value of the
Indicator of Carrier Type Priority parameter
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Priority Definition - Example
RAB ID ARP Traffic Class THP Bear Type
A 1 Interactive 3 DCH
B 1 Interactive 3 HSDPA
C 2 Conversational DCH
D 2 Background DCH
E 2 Background HSDPA
F 2 Streaming DCH
Services with different ARP/TC/THP/Bear:
ARP is the top-priority, and HSDPA over DCH
TC is the top-priority, and HSDPA over DCH
RANK ARP Traffic Class THP Bear Type
B 1 Interactive 3 HSDPA
A 1 Interactive 3 DCH
C 2 Conversational DCH
F 2 Streaming DCH
E 2 Background HSDPA
D 2 Background DCH
RANK Traffic Class ARP THP Bear Type
C Conversational 2 DCH
F Streaming 2 DCH
B Interactive 1 3 HSDPA
A Interactive 1 3 DCH
E Background 2 HSDPA
D Background 2 DCH
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Priority Definition in Huawei Implementation
User Priority
ARP 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
User Priority
ERROR 1 1 1 1 1 2 2 2 2 2 3 3 3 3
User Integrate Priority:
- For multiple-RAB users, determined by the service with the highest
RAB Integrate Priority.
User Priority: ☺ Gold (1) ☺ Silver (2) ☺ Bronze (3)
Typical Mapping of “ARP” and “User Priority”
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GBR Configuration in Huawei Implementation
– For R99 I/B services Uplink BE Guarantee Bitrate and Downlink BE Guarantee Bitrate are configurable
respectively per cell. Uplink BE Guarantee Bitrate is used in BE downsizing due to uplink cell basic congestion. Downlink BE Guarantee Bitrate is used in BE downsizing due to downlink coverage and
downlink cell basic congestion.
– For R99 and HSDPA RT services GBR is in accordance with the requested guaranteed bit rate in RAB parameters.
– For HSDPA I/B services Different GBRs are configured for Gold/Silver/Copper user.
Gold Silver Copper
Uplink 64kbps 64kbps 64kbps
Downlink 64kbps 64kbps 64kbps
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Overview
PUC
CAC
IAC
LDR
OLC
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Potentioal User Control
The PUC algorithm controls the cell selection of a potential UE and prevents an idle UE from
camping on a heavy load cell.
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Potentioal User ControlCell load comes with three levels: heavy, normal, and light.
When cell load is higher than the load level division upper threshold plus the load level division
hysteresis, it is decided to be heavy.
When cell load is lower than the load level lower threshold plus the load level division hysteresis, it
is decided to be light.
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Potentioal User Control
Based on the cell load, PUC works as follows:
If the cell load becomes heavy, PUC modifies cell selection and reselection
parameters and broadcasts them through system information. In this way, PUC
leads UEs to neighboring cells with light load.
If the cell load becomes normal, PUC uses the cell selection and reselection
parameters configured on the LMT.
If the cell load becomes light, PUC modifies cell selection and reselection
parameters and broadcasts them through system information. In this way, PUC
leads UEs to this cell.
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Overview
PUC
CAC
IAC
LDR
OLC
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Resource Admission Check Overview
Affected users Users in connected mode
Procedure Make decision whether to admit
new users or service upgrade
according to the available system
resources.
Resources to
check
1. DL Channelization Code
2. Radio Resource: Power /
Interference
3. Credit: Resource
4. Iub transmission bandwidth
For
HSDPA/HSUPA
Maximum user number per Cell /
NodeB
Admission request
Code resource based admission?
Credit resource based admission?
Iub resourcebased admission?
Resource admission passed
Power resource based admission?
Yes
Yes
Yes
Yes
Yes
Resource admission denied
No
No
No
No
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Admission Check of Radio Resource
UL and DL independently
On the basis of TCP / RTWP
On the basis of equivalent user number
Request initiation
Uplink calladmission desicion
Admitted?
Downlink calladmission desicion
Admitted?
Request admitted Request rejected
End
No
No
Yes
Yes
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Admission Algorithm Selection
Algorithm 1: based on TCP/RTWP measurement and load increment estimation
Downlink:
Load level definition: TCP (Transmitted Carrier Power)
Uplink:
Load level definition: load factor
Load increment of the new request is taken into consideration.
Algorithm 2: based on static Equivalent Number of Users calculation
Standard user: 12.2kbps AMR with active factor 100%.
Algorithm 3: based on current TCP/RTWP measurement
Based on TCP/RTWP measurement;
Load increment of the new request is not taken into consideration
RTWP
PNUL 1
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Uplink Admission Algorithm 1 & 3
)/( NoEcFun
Uplink admission control request
Get measured RTWP and calculatethe current uplink load factor.
Calculate the increment of theuplink load due to the request.
Get the predicted uplink loadfactor.
RTWPPN
UL 1
LUULpredictedUL ,
Compare the predicted value withadmission threshold
! Increment is always equal to ZERO when
algorithm 3 is applied
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Downlink Admission Algorithm 1&3
)/_,/( NoEcCPICHNoEcFunP
Downlink admission control request
Get measured current TCP
Calculate the increment of thedownlink power due to the request.
Get the predicted downlink totalpower
Compare the predicted power withadmission threshold
TCP
PTCPP predicted
! Increment is always equal to ZERO when
algorithm 3 is applied
)()1()/_(/1
/)1(
1010
10 NPNECPICH
P
NE
NENP
Nc
CPICH
Nc
Nc )(
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Priority Handling of Admission Check
Parameters Default value
UL Handover access threshold 80%
UL threshold of Conv AMR service 75%
UL threshold of Conv non_AMR service 75%
UL threshold of other services 60%
• Threshold for uplink radio resource admission check
Parameters Default value
DL Handover access threshold 85%
DL threshold of Conv AMR service 80%
DL threshold of Conv non_AMR service 80%
DL threshold of other services 75%
•Threshold for downlink radio resource admission check
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Code Management
Code management is used to manage the code resource between all the physical channels, including common channel (CCH) e.g. PCPICH and PCCPCH, dedicated channel (DPCH), and shared channel (HSDPA).
DPCHCCH
SF=16SF=8
SF=4
HSDPA
Code for DPCH:- Dynamically allocated
Code for common channel:- Reserved
Code for HSDPA:- Shared with R99 (Refer to HSDPA part)
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Code Allocation Mechanism
Reserve the codes with smallest SF to improve utilization rate of whole code tree.
On the basis of maximum free sub-tree
Less code fragments are left
SF=256SF=128 ┏ ━ ●C(256, 0): PCPI CH
┏ 0 ┫SF=64 ┃ ┗ ━ ●C(256, 1): PCCPCH
┏ 0 ┫┃ ┃ ┏ ━ ●C(256, 2): AI CH┃ ┗ 1 ┫
SF=32 ┃ ┗ ━ ●C(256, 3): PI CH┏ 0 ┫
SF=16 ┃ ┗ ━ ●C(64, 1): SCCPCH┏ 0 ┫┃ ┃ ┏ ━ ●C(128, 2): DPCH┃ ┃ ┏ ━ 2 ┫┃ ┃ ┃ ┃┃ ┗ 1 ┫ ┗ ━ ○ 3
SF=8 ┃ ┗ ━ ○3┏ 0 ┫
SF=4 ┃ ┗ ━ ○1┏ 0 ┫┃ ┗ ━ ○1┃┗ ━ ○1
┏ ━ ○2┃ ● Occupi ed code┗ ━ ○3 ○ Non-occupi ed code
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Admission Check of Iub Bandwidth
DPCH Service
Bandwidth consumption:
MBR * Active factor
HSDPA Service
Bandwidth consumption:
GBR * Active factor
Traffic ClassActive Factor
Scope
Common Channels 1
NodeB
SRB 0.9
Telephony (AMR&VOIP) 0.7
R99 Conversational (VP) 1
R99 Streaming 1
R99 Interactive 0.9
R99 Background 0.9
HSDPA Streaming 1
HSDPA Interactive 0.9
HSDPA Background 0.9
Configurable per service type
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Admission Check of NodeB Credit
Admission Check:
Credits of local cell
Credits of local cell group
Credits of NodeB
Credit Consumption Law:
Reported from NodeB
In terms of SF
HSDPA is not involved