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HUAWEI TECHNOLOGIES CO., LTD.
3G Load Control
February 2012
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HISILICON SEMICONDUCTOR
HUAWEI TECHNOLOGIES CO., LTD. Page 2 Page 2
Contents
Load Control: Introduction
Load Control: Intelligent Access Control
Load Control: Load Reshuffling
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HUAWEI TECHNOLOGIES CO., LTD. Page 3
Load Control exists in all phases
Load Control is used to keep system stable, maximize system capacity while ensuring the cover
3. After UE access2. During UE access1. Before UE access
Time
LDRCACPUC
OLC
IAC
PUC: Potential User Control
CAC: Call Admission Control
IAC: Intelligent Admission Control
LDR: Load Reshuffling
OLC: Overload Control
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HUAWEI TECHNOLOGIES CO., LTD. Page 4
Load control features
PUC
The function of PUC is to balance traffic load among inter-frequency cells. By modifying cell sel
reselection parameters and broadcasting them through system information, PUC leads UEs to c
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, reconfigurati
requests or service request, according to the resource status of the cell (codes, power, credits,
IAC
The function of IAC is to increase the access success rate with the current QoS assured throug
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 reac
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) o
releasing UEs when the cell is overloaded. The purpose of OLC is to ensure the stability of the
of most UEs.
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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 reac
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) o
releasing UEs when the cell is overloaded. The purpose of OLC is to ensure the stability of the
of most UEs.
How to check
LST UCELLALG
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Contents
Load Control: Introduction
Load Control: Intelligent Access Control
Load Control: Load Reshuffling
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Load Control: IAC
Intelligent Access Control (IAC) function target is to increase RRC and RAB success rate and it is d
parts.
IAC for RRC
Page 8
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
DRD
SUCCEED
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Load Control: IAC (RRC)
Page 9
Service-based
redirection
Depending on requested service and cell load, appropriate cell is chosen. For example, PS calls casecond carrier or voice calls can be redirected to interRAT neighbors.
RRC CONNECTION REJECT (Redirection info) is sent to UE with cell reselection for Inter-freq acc
access.
Redirection
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
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Load Control: IAC (RRC)
Page 10
Service-based
redirection
Depending on requested service and cell load, appropriate cell is chosen. For example, PS calls casecond carrier or voice calls can be redirected to interRAT neighbors.
RRC CONNECTION REJECT (Redirection info) is sent to UE with cell reselection for Inter-freq acc
access.
RedirectionHow to check redirection:
LST UREDIRECTION
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
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Load Control: IAC (RRC)
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RRC CAC
Code
RRC connection request and HO services only need to have available codes Other services needs to leave at least DLHoCeCodeResvSF
Power In case cell load is higher than UL or DL OLC trigger, RRC requests are not accepted.
Credits
RRC connection request and HO services only need to have available credits
Other services needs to leave at least DLHoCeCodeResvS
Iub Check if there is available bandwidth for this signalling connection
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
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Load Control: IAC (RRC)
Page 12
RRC CAC
Code
RRC connection request and HO services only need to have available codes Other services needs to leave at least DLHoCeCodeResvSF
Power In case cell load is higher than UL or DL OLC trigger, RRC requests are not accepted.
Credits
RRC connection request and HO services only need to have available credits
Other services needs to leave at least DLHoCeCodeResvS
Iub Check if there is available bandwidth for this signalling connection
How to LST UCE
How to
LST UCE
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
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Load Control: IAC (RRC)
Page 13
DRD
After admission fail, DRD tries to select another cell among cells with same coverage (blind HO). Insuccess to access, another one in the list is tried.
In case there is no more appropriate neighbors, redirection is done (in case switch is ON)
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
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Load Control: IAC (RRC)
Page 14
DRD
After admission fail, DRD tries to select another cell among cells with same coverage (blind HO). Insuccess to access, another one in the list is tried.
In case there is no more appropriate neighbors, redirection is done (in case switch is ON).
RRCconnection
request
Service-basedredirection
Redirection
RRC CAC
How to check redirection status:
LST UDRD
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Load Control: IAC (RAB)
IAC for RAB
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RAB setuprequest
Inter-freqDRD
Ratenegotiation
Try anotherneighbor cell
Fa
SUCC
CAC SUCC
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Load Control: IAC (RAB)
Target is to select a suitable cell for UE to access according to service priority and cell load (in caseactive). RNC prepares a list with blind HO neighbors and assigns cell with highest service priori
MBR, GBR, initial bit rate and target bit rate are assigned.
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Inter-freqDRD
Ratenegotiation
RAB setuprequest
Inter-freqDRD
Ratenegotiation
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Load Control: IAC (RAB)
Target is to select a suitable cell for UE to access according to service priority and cell load (in caseactive). RNC prepares a list with blind HO neighbors and assigns cell with highest service priori
MBR, GBR, initial bit rate and target bit rate are assigned.
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Inter-freqDRD
Ratenegotiation
How to check inter-freq DRD status:
LST UDRD
RAB setuprequest
Inter-freqDRD
Ratenegotiation
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Load Control: IAC (RAB)
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RAB CAC
Code Need to leave at least DLHoCeCodeResvSF
Power
Three different algorithms. Firstly UL is checked, then DL.
UL uses Algorithm 2: ENU
DL uses Algorithm 1: Load increase
Credits Need to leave at least DLHoCeCodeResvS
Iub Check if there is available bandwidth for GBR
User Max
Max cell HSDPA /HSUPA user number and max NodeB HSDPA/HSUPA user number is taking intonumber exceeds, user is degraded to R99.
RAB setuprequest
Inter-freqDRD
Ratenegotiation
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Load Control: IAC (RAB)
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RAB CAC
Code Need to leave at least DLHoCeCodeResvSF
Power
Three different algorithms. Firstly UL is checked, then DL.
UL uses Algorithm 2: ENU
DL uses Algorithm 1: Load increase
Credits Need to leave at least DLHoCeCodeResvS
Iub Check if there is available bandwidth for GBR
User Max
Max cell HSDPA /HSUPA user number and max NodeB HSDPA/HSUPA user number is taking intonumber exceeds, user is degraded to R99.
How to check if User Max is enabled (HSxPA_UU_ADCTRL switch):
LST UCELLALGOSWITCH
How to check algorithm:
LST UCELLALGOSWITCH
How to CAC thresholds:
LST UCELLCAC
RAB setuprequest
Inter-freqDRD
Ratenegotiation
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Load Control: IAC (RAB)
In case admission fails, another neighbor cell is tried from the suitable list. Then Rate Negotiation aIn case all neighbors fails:
If requested service is HSDPA, services is degraded to R99 to try again.
If requested service is R99, interRAT DRD is tried (needs bling HO 3G2G neighbors)
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RAB setuprequest
Inter-freqDRD
Ratenegotiation
Try anotherneighbor
cell
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Contents
Load Control: Introduction
Load Control: Intelligent Access Control
Load Control: Load Reshuffling
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Load Control: LDR
The function of LDR is to reduce the load of a cell when the available resources of the cell reach th
congestion threshold.
Basic congestion state can be caused by insufficiency of power, codes, Iub or credits resources.
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Load Control: LDR
The function of LDR is to reduce the load of a cell when the available resources of the cell reach th
congestion threshold.
Basic congestion state can be caused by insufficiency of power, codes, Iub or credits resources.
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How toLST UCE
LST UN
LST UCE
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Load Control: LDR
When the cell is in basic congestion, RNC can take one of follow actions each period (duration set
ULDCPERIOD):
The list of actions and its order could be modified using MOD UCELLLDR.
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Resource UL/DL
LDR Actions
Inter-Freq HO
BE RateReduction
Inter-
RAT
CS HO
Inter-
RAT PS
HO
AMRReduction
Iu QoSRenegotiation
CodeReshuffling
MBMS PowerDowngrading
Power
Resource
UL
DL
Code
Resource
UL .
DL
NodeB Credit
UL
DL
Iub TransportResource
UL DL
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