zte_umts load balance feature description

Load Balance WCDMA RAN Feature Description

Load Balance Feature Description

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Load Balance Feature Description Version Date Author Approved By Remarks

V2.5 2009-1-20 Sha Xiubin Zheng Dan

V3.0 2009-2-27 Sha Xiubin Zheng Dan

© 2008 ZTE Corporation. All rights reserved.

ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.

Due to update and improvement of ZTE products and technologies, information of the document is subjected to change without notice.


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TABLE OF CONTENTS

1 Function Attribute ...................................................................................................... 1

2 Overview ..................................................................................................................... 1 2.1 Overview of the Functions ........................................................................................... 1 2.1.1 Load-based Multi-carrier Interoperation....................................................................... 1 2.1.2 Service-based Multi-carrier Interoperation................................................................... 3 2.1.3 Inter-RAT Load Balance .............................................................................................. 4

3 Load-based Multi-carrier Interoperation.................................................................. 4 3.1 Load Evaluating Factors.............................................................................................. 4 3.1.1 Uplink interference....................................................................................................... 4 3.1.2 Downlink power ........................................................................................................... 4 3.1.3 Code resources ........................................................................................................... 4 3.1.4 Coupling Operation Between These Factors .............................................................. 5 3.2 Load-based Multi-carrier Interoperation in Initial RRC procedure............................... 6 3.3 Load-based Multi-carrier Interoperation in RAB assignment ...................................... 6 3.4 Load-Based Multi-carrier Interoperation in Call holding procedure............................. 7

4 Service-based Multi-carrier Interoperation.............................................................. 7 4.1 Service-based Multi-carrier Interoperation in Initial RRC procedure........................... 7 4.2 Service-based Multi-carrier Interoperation in RAB Assignment .................................. 9 4.3 Service-based Multi-carrier Interoperation in Call holding procedure ....................... 10

5 Coupling of Load-based and Service-based Multi-carrier Interoperations........ 10

6 Inter-RAT Load Balance Strategy........................................................................... 11 6.1 Directed Retry Triggered by Inter-RAT Balancing..................................................... 11 6.2 Directed Retry Triggered by Admission Failure......................................................... 11

7 Configuration and Parameters ............................................................................... 11 7.1 Parameter List ........................................................................................................... 11 7.2 Parameter Configuration ........................................................................................... 12 7.2.1 Load Balance Switch of Initial RRC Procedure ......................................................... 12 7.2.2 Load Balance Switch of RAB Assignment Procedure............................................... 13 7.2.3 Load Balance Switch of Call holding procedureing Procedure ................................. 13 7.2.4 Load balance switch for downlink power................................................................... 14 7.2.5 Load Balance Switch for Uplink Interference ............................................................ 15 7.2.6 Load Balance Switch for Code Resource.................................................................. 15 7.2.7 Downlink Power Weight for Load Balance ................................................................ 16 7.2.8 Uplink Interference Weight for Load Balance............................................................ 16 7.2.9 Code Weight for Load Balance.................................................................................. 17 7.2.10 UTRAN Downlink Load Balance Threshold-Power................................................... 18 7.2.11 Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-

Power......................................................................................................................... 18 7.2.12 UTRAN Uplink Load Balance Threshold-Interference .............................................. 19 7.2.13 Permitted Payload Difference Uplink Load Threshold in Inter-frequency Cells-

Interference................................................................................................................ 20 7.2.14 UTRAN Downlink Load Balance Threshold-Code .................................................... 21 7.2.15 Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-

Code .......................................................................................................................... 22 7.2.16 Service Balance Switch of Initial RRC Procedure ..................................................... 23 7.2.17 Service Balance Switch of RAB Assignment Procedure........................................... 24


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7.2.18 Service Balance Switch of Call holding procedureing Procedure ............................. 24 7.2.19 Preferred Traffic Type................................................................................................ 25 7.2.20 Share Cover Indication (utranRelation) ..................................................................... 25 7.2.21 Share Cover Indication (gsmRelation) ...................................................................... 26 7.2.22 HSPA Support Method .............................................................................................. 27 7.2.23 Inter-RAT Downlink Load Balance Threshold-Power................................................ 27 7.2.24 Inter-RAT Uplink Load Balance Threshold-Interference ........................................... 28

8 Counter And Alarm .................................................................................................. 29 8.1 Counter List ............................................................................................................... 29 8.2 Alarm List ................................................................................................................... 29

9 Glossary .................................................................................................................... 29


ZTE Confidential Proprietary © 2008 ZTE Corporation. All rights reserved. 1

1 Function Attribute System version: [RNC V3.07.300, Node B V4.00.100, OMMR V3.17.300, OMMB V4.00.100]

Attribute: Mandatory function

Related NE: UE NodeB RNC MSCS MGW SGSN GGSN HLR √ √ √ - - - - - Note: *-: Non-related NE *√: Related NE

Dependency: [None]

Exclusion: None

Remarks: None.

2 Overview

2.1 Overview of the Functions Load balancing includes the intra-system load balancing (load-based multi-carrier interoperation, service-based multi-carrier interoperation) and Inter-RAT load balancing. Its chief principal is to deploy reasonably the inter-cell traffic based on the load of cell and the neighboring cell configuration (ShareCover, GsmShareCover), and use the system resources effectively to enhance the system capacity and QoS.

2.1.1 Load-based Multi-carrier Interoperation

Load-based multi-carrier interoperation selects a target cell preferably in Initial RRC procedure, RAB assignment, and call holding procedure, rather than triggering the handover actively. That is, if a cell where the UE resides is overloaded, when selecting a target cell in Initial RRC procedure, RAB assignment, and call holding procedure, RNC will include the cell and its neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship into the target cell list. The cell with lowest overall load in the list is selected as the target cell for access or handover. Its application scenarios are classified into three types:

• Initial RRC procedure: involving Initial RRC procedure.

• RAB assignment: involving RAB assignment.



• Call holding procedure: involving handover, relocation from other system or RNC to local RNC, call re-establishment triggered by CELL UPDATE, state transition from non-CELL_DCH to CELL_DCH.

In the three scenarios, related functions are controlled by three switches: InitRrcLBSw, RabAssLBSw, CallHoldLBSw.

Principles of target cell selection in load-based multi-carrier interoperation:

1) Combine the target cell of UE for access/handover and its neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship into a target cell set (named Set);

2) Pick a set (named Set1) of cells which the UE frequency-band supports from the target cell set;

3) Select the cell with the lowest overall load which can provide the requested service from the cell Set1.

The cell load is evaluated by three factors: uplink interference (RTWP), downlink power (TCP), and downlink code resources. The related functions of the three factors are controlled by three switches: UlLdBalPwrSwch, DlLdBalPwrSwch, and LdBalCdSwch. The restricted resource may be different in different scenarios. For example, for cells in some areas, downlink power is frequently limited, while in cells of another area, the code resource is frequently limited. Therefore, different weights can be configured according to the three factors, so as to adapt to different application scenarios.

Note: for cells supporting HSPA, the three factors are valued according to the following principles.

The uplink interference is measured by the uplink payload:

Uplink payload = Load generated by uplink DCH + Load generated by non-scheduling E-DCH + Load generated by the throughput of GBR services of scheduling E-DCH

“Load generated by uplink DCH + Load generated by non-scheduling E-DCH” can be measured by NodeB RSRPS, while “Load generated by the throughput of GBR services of scheduling E-DCH” can be calculated by the uplink interference predictive formula. See <ZTE UMTS Admission Control Feature Description>.

The downlink power is measured by the downlink payload:

0NOHSDSCHPower HSDSCHRequiredPower

Snum

ii=

= + ∑downlink payload

Where,

NOHSDSCHPower refers to the Transmitted carrier power of all codes not used for HS-PDSCH or HS-SCCH transmission that is reported by the NodeB.

HSDSCHRequiredPoweri It indicates the HS-DSCH Required Power of the scheduling priority i of the current cell.



Downlink code resources are measured by the code resource occupancy of channels other than HS-PDSCH.

2.1.2 Service-based Multi-carrier Interoperation

The serving cells can be categorized by service type (HspaSptMeth) into five types:

1) Cells supporting HSUPA and HSDPA;

2) Cells supporting HSUPA, HSDPA and DCH;

3) Cells supporting HSDPA and DCH;

4) Cells supporting HSDPA only;

5) Cells which do not support HSUPA and HSDPA.

And by frequency-band, the cells can be divided into UMTS900 and UMTS1800. The services carried by the cells may vary according to cell types. For example, the cells which do not support HSUPA and HSDPA mainly carry voice services, while cells supporting HSDPA and DCH mainly carry data services. As a result, the parameter “PrefTrafType” is defined for each cell to instruct which type of service is preferred for that cell. The operator can set the parameter flexibly to satisfy the requirements in different scenarios.

PrefTrafType definition:

• Cs prefer is designed for receiving voice services.

• Ps prefer is designed for receiving data services.

• Cs+Ps prefer is designed for receiving frequency services such as UMTS900 services.

• Non prefer indicates no prefer property.

Service-based multi-carrier interoperation selects a target cell preferably in Initial RRC procedure, RAB assignment, and call holding procedure, rather than triggering the handover actively. That is, when selecting a target cell in Initial RRC procedure, RAB assignment, and call holding procedure, RNC will select a proper cell as the target cell for access or handover based on specific service originated by the user equipment (UE). Its application scenarios are classified into three types:

• Initial RRC procedure: involving Initial RRC procedure.

• RAB assignment: involving RAB assignment.

• Call holding procedure: involving handover, relocation from other system or RNC to local RNC, call re-establishment triggered by CELL UPDATE, state transition from non-CELL_DCH to CELL_DCH.



In the three scenarios, related functions are controlled by three switches configured by OMC: InitRrcSBSw, RabAssSBSw, CallHoldSBSw.

2.1.3 Inter-RAT Load Balance

The Inter-RAT load balance indicates the UE will be assigned to 2G system through Inter-RAT directed retry during RAB assignment when the cell where the UE resides is overloaded.

3 Load-based Multi-carrier Interoperation

3.1 Load Evaluating Factors

3.1.1 Uplink interference

The uplink interference of a cell uses the RTWP (HSPA cells use uplink payload) as the load evaluating criterion. When the uplink load is heavy, load balancing is required, that is, the traffic is balanced to cells of other carriers to reduce the cell load. Thus, the stability of the system is ensured.

When the uplink interference exceeds the preset threshold (UlLoadNeedBal2U), the load of the cell is heavy. The load-based multi-carrier interoperation should be triggered.

3.1.2 Downlink power

The downlink power of a cell uses the CTCP (HSPA cells use downlink payload) as the load evaluating criterion. When the uplink load is heavy, load balancing is required, that is, the traffic is balanced to cells of other carriers to reduce the cell load. Thus, the stability of the system is ensured.

When the downlink power exceeds the preset threshold (DlLoadNeedBal2U), the load of the cell is heavy. The load-based multi-carrier interoperation should be triggered.

3.1.3 Code resources

By using load measuring method of the downlink channelization code resources, calculate the proportion of the quantity of code words in use to the total quantity of code words to indicate the load of the downlink channelization code resources. Then, take SF = 128 as the statistic granularity of the code resources. Because the HSDPA is shared, herein we just calculate the occupancy of code resource of DCH.

When the downlink code resources exceed the preset threshold (DlCdLdNeedBal2U), the load of the cell is heavy. The load-based multi-carrier interoperation should be triggered.



3.1.4 Coupling Operation Between These Factors

Three factors should be taken into consideration when evaluating the load: uplink interference, downlink power, and downlink code resources. The restricted resources vary in different scenarios. For example, for cells in some areas, downlink power is restricted usually, while in cells of another area, the code resources are restricted instead. Therefore, different weights can be configured as required according to the three factors, so as to adapt to different application scenarios. When evaluating the load of cell, the load weight, load, and load threshold of the three factors are tacken into account to calculate the cell overall load. See the following calculation method.

∑=

−−−=

k

1ii

i

iii Weight*Delta

LoadSourceThrdSourceLoadadDestThrdLoDestLoad*2Weight ））（）（（

The meanings of the parameters are as follows:

k indicates the number of factors that are considered in load balancing. The value is 3 at present, which indicates code resources, downlink power, and uplink interference.

DestLoad indicates the actual load of the target cell (the uplink interference is measured by RTWP or uplink payload; the downlink power is measured by CTCP or downlink payload; the downlink code resources are measured by the occupancy of SF = 128 code resources of non-HS-DSCH channels).

DestThrdLoad indicates the load balancing threshold (corresponds to DlLoadNeedBal2U, UlLoadNeedBal2U, and DlCdLdNeedBal2U configured in the target cell) of the target cell configured by OMC.

SourceLoad indicates the load of the source cell.

SourceThrdLoad indicates the load balancing threshold (corresponds to DlLoadNeedBal2U, UlLoadNeedBal2U, and DlCdLdNeedBal2U configured in the source cell) of the source cell.

Delta indicates the load balancing threshold difference (corresponds to ExtraCDeltaTrd, ExtraCDeltaTru, and ExtraCDeltaCdTrd configured in the source cell) of the source cell configured by OMC.

Weighti indicates the weight (corresponds to DlLdBalPwrWeight, UlLdBalPwrWeight, and LdBalCdWeight configured in the source cell) of each factor.

The three factors - code resources, downlink power, and uplink interference - can be controlled by three switches: LdBalCdSwch, DlLdBalPwrSwch, and UlLdBalPwrSwch. When a factor is switched to OFF, it will not be taken into consideration in load balancing, and the corresponding weight is invalid (0). The sum of weights (DlLdBalPwrWeight, UlLdBalPwrWeight, and LdBalCdWeight) of each factor is 1, which is ensured by the configuration. If all of the three factors are switched to OFF, load balancing is not performed.

If the load of the code resources exceeds its threshold of load balancing (DlCdLdNeedBal2U), or the load of downlink power exceeds its threshold of load balancing (DlLoadNeedBal2U), or the uplink interference exceeds its threshold of load balancing (UlLoadNeedBal2U), the load of the cell is heavy. Otherwise, the load is light. According to this principle, the serving cells and their UE-supporting neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship are included into two cell lists, one for the heavy load cells and the other for the light load cells. Weight



calculations are performed for each cell in the two lists according to the above formula, and weights are sorted in an ascending order. The smaller the weight is, the lower the load is. The multi-carrier operation is triggered when the target cell of UE for access/handover is overloaded. That is, in Initial RRC procedure, RAB assignment, and call holding procedure, select a cell with the lowest weight (lowest evaluating of load) from target cell and its neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship to access, and the cell should be supported by UE, and can be carried by services.

3.2 Load-based Multi-carrier Interoperation in Initial RRC procedure In the initial RRC procedure, if InitRrcLBSw switch is set to ON, the load of the serving cell meet the requirements of load-based multi-carrier interoperation (see 3.1 Load Evaluating Criterion), and the serving cell have inter-frequency neighboring cells with “Overlap” or “ Covers” （ ShareCover ） relationship, the load-based multi-carrier interoperation in Initial RRC procedure will be triggered, and a cell with the lowest load will be selected for access

Note: In the initial RRC procedure, the specific services and some capabilities of the UE are not known. To avoid the balance failure due to balancing UE to the band that the UE does not support, the neighboring cell whose frequency band is different from the current serving cell will not be taken into account as the target cell of the load balancing.

3.3 Load-based Multi-carrier Interoperation in RAB assignment In the RAB assignment procedure, if RabAssLBSw switch is set to ON, the load of the serving cell meet the requirements of load-based multi-carrier interoperation (see 3.1 Load Evaluating Criterion), and the serving cell have inter-frequency neighboring cells which have “Overlap” or “ Covers”（ShareCover） relationship with the serving cell, the load-based multi-carrier interoperation in RAB assignment procedure will be triggered, that is the target cell selection is triggered by the load balancing in RAB assignment procedure.

After the introduction of HSDPA and HSUPA, the cells can be categorized into multiple types:

1) Cells supporting HSUPA and HSDPA.

2) Cells supporting HSUPA, HSDPA and DCH.

3) Cells supporting HSDPA and DCH.

4) Cells supporting HSDPA only.

5) Cells which do not support HSUPA and HSDPA. There are also UMTS2100 and UMTS 900 cells of different bands. The UE provides different support to these cells. Therefore, in the load-based multi-carrier interoperation in RAB assignment, the service properties and UE capabilities should be taken into consideration to select the target cell. The specific principles are as follows:



(1) Combine the target cell of UE for access/handover and its neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship into a target cell Set;

(2) Pick a set (named as Set1) of cells which the UE band supports from the target cell set in step (1);

(3) Pick a set (named as Set2) of cells which the UE currently originated service supports from Set1 in step (2);

(4) Select the lowest load cell as the final target cell for access/handover in Set2.

See services and target cell types which can carry the services in the following table:

Table 1 Services and target cell types which can carry the services

Service Type DCH/DCH HS-DSCH/DCH HS-DSCH/E-DCH Target cell types which can carry the services

Cells which do not support HSUPA and HSDPA Cells supporting HSDPA and DCH Cells supporting HSUPA, HSDPA, and DCH

Cells supporting HSDPA and DCH Cells supporting HSUPA, HSDPA, and DCH

Cells supporting HSUPA and HSDPA Cells supporting HSUPA, HSDPA, and DCH

That is to say, the cell whose service type is not included in the above table will be considered as an unsupported cell, and excluded out of the cell list.

3.4 Load-Based Multi-carrier Interoperation in Call holding procedure In handover, relocation from other system or RNC to local RNC, call re-establishment triggered by CELL UPDATE, state transition from non-CELL_DCH to CELL_DCH, if CallHoldLBSw is set to ON, the judgment of load-based multi-carrier interoperation in call holding procedure is performed. Its handling procedure is the same as that of the load-based multi-carrier interoperation in RAB assignment.

4 Service-based Multi-carrier Interoperation

4.1 Service-based Multi-carrier Interoperation in Initial RRC procedure In Initial RRC procedure, if InitRrcSBSw is set to ON, and the cell where the UE currently resides has inter-frequency neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship, the most suitable cell is selected from the currently cell and these neighboring cells based on the establish cause of RRC request, UE supporting status, and cell properties (PrefTrafType, HspaSptMeth) to access.



For detailed preference rules of the target cell is as follows:

For the Establishment cause of Originating Conversational Call,Terminating Conversational Call,Emergency Call,Inter-RAT cell re-selection,Inter-RAT cell change order,Registration, Detach,Call re-establishment,Originating Low Priority Signalling,Terminating Low Priority Signalling:

Determine whether the following preferred cells exist in the light loaded target cells:

Cs preferred cells which do not support HSUPA and HSDPA is preferred

Cs+Ps preferred cells which do not support HSUPA and HSDPA is next preferred

If no light loaded cell is selected in the step above, select the first cell in the load ranking list for access(see 3.1.4 Coupling Operation Between These Factors).

For the Establishment cause of MBMS reception, MBMS ptp RB request:

The current cell is the target cell.

For the Establishment cause of Originating Streaming Call,Originating Interactive Call,Originating Background Call,Terminating Streaming Call,Terminating Interactive Call,Terminating Background Call,Originating High Priority Signalling,Terminating High Priority Signalling:

The table 2 is the target cell selection rules for these calls.

Table 2 List of Preferred Target Cells Table of Sequence of Cells of Services

DCH/DCH HS-DSCH/DCH, HS-DSCH/E-DCH

Establishment causes: Originating Streaming Call, Originating Interactive Call, Originating Background Call, Terminating Streaming Call, Terminating Interactive Call, Terminating Background Call, Originating High Priority Signaling, Terminating High Priority Signaling

Determine whether the following preferred cells exist in the lightly loaded target cells: Ps preferred cells which do not support HSUPA and HSDPA Cs+Ps preferred cells which do not support HSUPA and HSDPA The first cell that meets the preference rule is the preferred cell. If no cell is selected in the step above, select the first cell in the load ranking list for access.

Determine whether the following preferred cells exist in the lightly loaded target cells: Ps preferred cells which can support the R5 Cs + Ps preferred cells which can support the R5 The first cell that meets the preference rule is the preferred cell. If no cell is selected in the step above, select the first cell in the load ranking list for access. Cells supporting R5 indicates: Cells supporting HSUPA and HSDPA; Cells supporting HSUPA, HSDPA, and DCH; Cells supporting HSDPA and



DCH; Cells supporting HSDPA only. The four types share the same priority.

Note: The lightly-loaded cell in the table 2 refers to the cell: whose code resource load is less than the threshold of code load balancing (DlCdLdNeedBal2U), and downlink power is less than the threshold of download load balancing (DlLoadNeedBal2U), and uplink interference is less than the threshold of uplink load balancing (UlLoadNeedBal2U).

4.2 Service-based Multi-carrier Interoperation in RAB Assignment In RAB assignment, if RabAssSBS is set to ON, the system will perform the judgment of the service-based multi-carrier interoperation in RAB assignment. After the introduction of HSDPA and HSUPA, the cells (HspaSptMeth) can be categorized into multiple types: 1) Cells supporting HSUPA and HSDPA. 2) Cells supporting HSUPA, HSDPA and DCH. 3) Cells supporting HSDPA and DCH. 4) Cells supporting HSDPA only. 5) Cells which do not support HSUPA and HSDPA. And by band, the cells can be divided into UMTS900 and UMTS1800. The supporting capabilities of UE vary by type of the cell. Consequently, the sorting and selection of the target cell should be based on the UE capabilities, current established services, and the Prefer property of each cell. The detailed procedure is as follows:

1) Combine the current cell where UE resides and its neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship into a target cell set (named Set);

(2) Exclude the cells whose bands are not supported by UE, and the cells which are not supported by the current service originated by UE from the Set in step (1). The remained cells form the a target set named Set1. The cell types which are supported by the current services of UE are as follows:

Table 3 Table of Cell Types Supported by Current Services of UE

Service Type DCH/DCH HS-DSCH/DCH HS-DSCH/E-DCH Target cell types which can carry the services

Cells which do not support HSUPA and HSDPA Cells supporting HSDPA and DCH Cells supporting HSUPA, HSDPA, and DCH

Cells supporting HSDPA and DCH Cells supporting HSUPA, HSDPA, and DCH

Cells supporting HSUPA and HSDPA Cells supporting HSUPA, HSDPA, and DCH

That is to say, the cell whose service type is not included in the above table will be considered as an unsupported cell, and excluded out of the cell list.

(3) Cells in Set1 in step (2) will be sorted according to specific service types and the Prefer property of cells (PrefTrafType). See below table.



Table 4 Table of Sequence of Cells of Services

Sequence of Cells CS service Cs preferred cells

Cs + Ps preferred cells None preferred cells Ps preferred cells

Ps service Ps preferred cells Cs + Ps preferred cells None preferred cells Cs preferred cells

CS + PS services Cs + Ps preferred cells Ps preferred cells None preferred cells Cs preferred cells

(3) If the HCS function is introduced for cells, the cells should be sorted based on the HCS priorities of target cells in the descending order in the sorting in step (3). (The HCS priority ranges from 0 to 7. 0 is the lowest priority with relatively wide coverage, while 7 is the highest priority with relatively small coverage). That is to say, sort the listed cells based on the HCS properties in the precondition of meeting the prefer property.

Based on the deletion and preference sorting procedures on the listed target cells in the above steps, select the first cell in the list as the target cell for access or handover.

4.3 Service-based Multi-carrier Interoperation in Call holding procedure In handover, relocation from other system or RNC to local RNC, call re-establishment triggered by CELL UPDATE, state transition from non-CELL_DCH to CELL_DCH, if CallHoldLBSw is set to ON, the judgment of service-based multi-carrier interoperation in call holding procedure is performed. Its handling procedure is the same as that of the service-based multi-carrier interoperation in RAB assignment.

5 Coupling of Load-based and Service-based Multi-carrier Interoperations Both load-based and service-based multi-carrier interoperations function in the initial access and call holding procedure, and will not trigger handover actively but select the preferred cell and sort cells. The system load holds a great impact on the stability of system, thus the priority of load is higher than that of services. That is to say, perform service-based preference sorting of cells is in the precondition of meeting the load requirement. For example: Firstly, select the target cell in the lightly-loaded target cells list (whose code resource loads are less than the thresholds of code load balancing (DlCdLdNeedBal2U), and downlink powers are less than the thresholds of downlink load balancing (DlLoadNeedBal2U), and uplink interferences are less than the thresholds of uplink load balancing (UlLoadNeedBal2U)) according to the service types and Prefer property of cells (PrefTrafType) by service-based multi-carrier interoperation strategy. If



all the cells whose loads are less than the thresholds can not bear the services, select the lightest loaded cell according to load-based multi-carrier interoperation strategy.

6 Inter-RAT Load Balance Strategy The Inter-RAT load balance indicates that if the cell where the UE resides is overloaded during RAB assignment, the UE will be assigned to 2G system through Inter-RAT directed retry.

According to the 3GPP 25.413 regulations, the directed retry indicates that RNC fails to reassign the CS service assigned by CN due to Directed retry, and RNC originates immediately the relocation from 3G to 2G in CS domain due to Directed retry, and then the CS service assigned by CN is relocated to 2G system. Currently, the CS service supported by 2G is mainly the AMR voice, Therefore, the directed retry refers to the directed retry of AMR voice.

6.1 Directed Retry Triggered by Inter-RAT Balancing When RNC receives the AMR service assignment message from CN, if the downlink load of the cell (CTCP or downlink payload) exceeds its Inter-RAT threshold of load balancing (DlLoadNeedBal2G), or the uplink interference of the cell (RTWP or uplink payload) exceeds its Inter-RAT threshold of load balancing (UlLoadNeedBal2G), and the UE supports 2G system and the current cell has neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship, the RNC will trigger the directed retry to try to hand over the service to 2G neighboring cells.

6.2 Directed Retry Triggered by Admission Failure When RNC receives the AMR service assignment message from CN, and is not admitted by the cell (see ZTE UMTS Admission Control Feature Description), if the UE supports 2G system and the current cell has neighboring cells which are with “Overlap” or “ Covers”（ShareCover） relationship, RNC will trigger the directed retry to try to hand over the service to 2G neighboring cells.

7 Configuration and Parameters

7.1 Parameter List Abbreviated name Parameter name InitRrcLBSw Load Balance Switch of Initial RRC Procedure RabAssLBSw Load Balance Switch of RAB Assignment Procedure CallHoldLBSw Load Balance Switch of Call holding procedureing Procedure DlLdBalPwrSwch Load Balance Switch for Downlink Power UlLdBalPwrSwch Load Balance Switch for Uplink Interference LdBalCdSwch Load balance switch for code



DlLdBalPwrWeight Downlink Power weight for load balance

UlLdBalPwrWeight Uplink Interference Weight for Load Balance LdBalCdWeight Code weight for load balance DlLoadNeedBal2U UTRAN Downlink Load Balance Threshold- Power

ExtraCDeltaTrd Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells –Power

UlLoadNeedBal2U UTRAN Uplink Load Balance Threshold-Interference ExtraCDeltaTru Permitted Payload Difference Uplink Load Threshold in Inter-frequency

Cells-Interference DlCdLdNeedBal2U UTRAN Downlink Load Balance Threshold -Code

ExtraCDeltaCdTrd Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-Code

InitRrcSBSw Service Balance Switch of Initial RRC Procedure

RabAssSBSw Service Balance Switch of RAB Assignment Procedure

CallHoldSBSw Service Balance Switch of Call holding procedureing Procedure

PrefTrafType Preferred Traffic Type ShareCover Share Cover Indication (utranRelation) GsmShareCover Share Cover Indication (gsmRelation) HspaSptMeth HSPA Support Method DlLoadNeedBal2G Inter-RAT Downlink Load Balance Threshold-Power(%) UlLoadNeedBal2G Inter-RAT Uplink Load Balance Threshold-Interference(dB)

7.2 Parameter Configuration

7.2.1 Load Balance Switch of Initial RRC Procedure

• Parameter Description

Parameter name Load Balance Switch of Initial RRC Procedure Abbreviated name

InitRrcLBSw

Description This parameter is a load balance switch which indicates whether the load balance function is open for initial RRC accessing procedure .

Range and Step

0: Closed 1: Inter-frequency Open 2: Inter-RAT Open 3: Inter-frequency and Inter-RAT Open

Unit N/A Default Value (note)

1: Inter-frequency Open



• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Load Balance Switch of Initial RRC Procedure

• Parameter Configuration

This parameter is a load balancing switch for RRC initial access.

7.2.2 Load Balance Switch of RAB Assignment Procedure


Parameter name Load Balance Switch of RAB Assignment Procedure Abbreviated name

RabAssLBSw

Description This parameter is a load balance switch which indicates whether the load balance function is open for RAB assignment procedure.

Range and Step



1: Inter-frequency Open

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Load Balance Switch of RAB Assignment Procedure


This parameter is a load balance switch which indicates whether the load balance function is open for RAB assignment procedure.

7.2.3 Load Balance Switch of Call holding procedureing Procedure


Parameter name Load Balance Switch of Call holding procedureing Procedure Abbreviated name CallHoldLBSw

Description This parameter is a load balance switch which indicates whether load balance function is open for call holding procedureing procedure. The application scenes include handover, relocation,



RAB re-establishment and FACH->DCH.

Range and Step



0: Closed

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information-> Load Balance Switch of Call holding procedureing Procedure


This parameter is a load balance switch which indicates whether load balance function is open for call holding procedureing procedure. The application scenes include handover, relocation, RAB re-establishment and FACH->DCH.

7.2.4 Load balance switch for downlink power


Parameter name Load Balance Switch for Downlink Power Abbreviated name

DlLdBalPwrSwch

Description This parameter is a switch indicating whether load balance based on downlink transmitting power is open or not.

Range and Step 0: Closed 1: Open


1: Open

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information-> Load Balance Switch for Downlink Power


This parameter is a switch indicating whether load balance based on downlink power is open or not.



7.2.5 Load Balance Switch for Uplink Interference


Parameter name Load Balance Switch for Uplink Interference

Abbreviated name

UlLdBalPwrSwch

Description This parameter is a switch indicating whether load balance based on uplink RTWP is open or not.


Unit N/A

Default Value (note)

0: Closed

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information-> Load Balance Switch for Uplink Interference


This parameter is a switch indicating whether load balance based on uplink interference is open or not.

7.2.6 Load Balance Switch for Code Resource


Parameter name Load Balance Switch for Code Resource

Abbreviated name

LdBalCdSwch

Description This parameter is a switch indicating whether load balance based on downlink channellization code resource is open or not.


Unit N/A


1: Open

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information-> Load Balance Switch for Code




This parameter is a switch indicating whether load balance based on code resources is open or not.

7.2.7 Downlink Power Weight for Load Balance


Parameter name Downlink Power Weight for Load Balance (%)

Abbreviated name

DlLdBalPwrWeight

Description

This parameter indicates the weight of downlink transmitting power. When evaluating the cell load, several factors such as downlink channellization code, downlink transmitting power and uplink RTWP are taken into account for load balance. Each factor is configured a weight, and sum of each factor’s (whose switch is open) weight is 1.

Range and Step [0, 100]% step 1%

Unit %


40%

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information-> Downlink Power Weight for Load Balance(%)


This parameter indicates the weight of downlink power resources in several factors of load balance. When evaluating the cell load, several factors such as code resources, downlink power and uplink interference are taken into account for load balance. The sum of each factor’s (whose switch is open) weight is 1.

7.2.8 Uplink Interference Weight for Load Balance


Parameter name Uplink Interference Weight for Load Balance (%)

Abbreviated name

UlLdBalPwrWeight

Description

This parameter indicates the weight of uplink RTWP. When evaluating the cell load, several factors such as downlink channellization code, downlink transmitting power and uplink RTWP are taken into account for load balance. Each factor is configured a weight, and sum of each factor’s (whose switch is open) weight is 1.

Range and Step [0,100]% step 1%

Unit %




0%

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Uplink Interference weight for Load Balance(%)


This parameter indicates the weight of uplink interference in several factors of load balance. When evaluating the cell load, several factors such as code resources, downlink power and uplink interference are taken into account for load balance. The sum of each factor’s (whose switch is open) weight is 1.

7.2.9 Code Weight for Load Balance


Parameter name Code Weight for Load Balance (%)

Abbreviated name

LdBalCdWeight

Description

This parameter indicates the weight of downlink channellization code. When evaluating the cell load, several factors such as downlink channellization code, downlink transmitting power and uplink RTWP are taken into account for load balance. Each factor is configured a weight, and sum of each factor’s (whose switch is open) weight is 1.


Unit %


60%

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Code weight for Load Balance(%)


This parameter indicates the weight of code resources in several factors of load balance. When evaluating the cell load, several factors such as code resources, downlink power and uplink interference are taken into account for load balance. The sum of each factor’s (whose switch is open) weight is 1.



7.2.10 UTRAN Downlink Load Balance Threshold-Power


Parameter name UTRAN Downlink Load Balance Threshold-Power (%)

Abbreviated name

DlLoadNeedBal2U

Description

This parameter indicates the downlink Power load threshold for load balance between UTRAN cells. If the downlink Power load of local UTRAN cell exceeds the threshold indicated by this parameter, the downlink load balance judgment is performed and UE in local cell may be balanced to other UTRAN cell.

Range and Step [0, 100]%

Unit %


55%

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->UTRAN Downlink Load Balance Threshold-Power(%)


This parameter indicates the downlink Power load threshold for load balance between UTRAN cells. If the downlink Power load of local UTRAN cell exceeds the threshold indicated by this parameter, the downlink load balance judgment is performed and UE in local cell may be balanced to other UTRAN cell.

7.2.11 Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-Power


Parameter name Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-Power (%)

Abbreviated name

ExtraCDeltaTrd

Description

This parameter indicates the downlink TCP load difference threshold between inter-frequency cells. When the downlink transmitting power of local cell exceeds the UTRAN Downlink TCP Load Balance Threshold and the downlink TCP difference of serving and inter-frequency cell exceeds the threshold indicated by this parameter, the inter-frequency cell is a target cell satisfying the condition of load balance.


Unit %


10%



• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Permmited Payload Difference Downlink Load Threshold in Inter-frequency Cells –Power(%)


This parameter indicates the downlink TCP load difference threshold between inter-frequency cells. It is used to evaluate the load of a cell as follows:

∑=

−−−=

k

1ii

i

iii Weight*Delta


Where,

k indicates the number of factors that are considered in load balancing. The value is 3 at present, which includes code resources, downlink power, and uplink interference.

DestLoad indicates the actual load of the target cell (the uplink interference is measured by RTWP; the downlink power is measured by CTCP; the downlink code resources are measured by the occupancy of SF = 128 code resources of non-HS-DSCH channels).





Weight indicates the weight (corresponds to DlLdBalPwrWeight, UlLdBalPwrWeight, and LdBalCdWeight configured in the source cell) of each factor.

7.2.12 UTRAN Uplink Load Balance Threshold-Interference


Parameter name UTRAN Uplink Load Balance Threshold-Interference (dB)

Abbreviated name

UlLoadNeedBal2U

Description This parameter indicates the uplink RTWP threshold for load balance between UTRAN cells. If the uplink RTWP of local UTRAN cell exceeds the threshold indicated by this parameter, the uplink load balance judgment is performed and UE in local cell



may be balanced to other UTRAN cell. Range and Step [0,62] dB step 0.1 dB

Unit dB


20dB

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->UTRAN Uplink Load Balance Threshold-Interference(dB)


This parameter indicates the uplink RTWP threshold for load balance between UTRAN cells. If the uplink RTWP of local UTRAN cell exceeds the threshold indicated by this parameter, the uplink load balance judgment is performed and UE in local cell may be balanced to other UTRAN cell.

7.2.13 Permitted Payload Difference Uplink Load Threshold in Inter-frequency Cells-Interference


Parameter name Permitted Payload Difference Uplink Load Threshold in Inter-frequency Cells-Interference (%)

Abbreviated name

ExtraCDeltaTru

Description

This parameter indicates the uplink RTWP load difference threshold between inter-frequency cells. When uplink RTWP of local cell exceeds UTRAN Uplink RTWP Load Balance Threshold and the uplink RTWP difference of serving and inter-frequency cell exceeds the threshold indicated by this parameter, the inter-frequency cell is a target cell satisfying the condition of load balance.

Range and Step [0, 100]%

Unit %


10%

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Permmited Payload Difference Uplink Threshold in Inter-frequency Cells-Interference(%)




This parameter indicates the uplink RTWP load difference threshold between inter-frequency cells. It is used to evaluate the load (Weight) of a cell as follows:

∑=

−−−=

k

1ii

i

iii Weight*Delta


Where,


DestLoad indicates the actual load of the target cell (the uplink interference is measured by RTWP; the downlink power is measured by CTCP; the downlink code resources are measured by the occupancy of SF = 128 code layer of non-HS-DSCH channels).






7.2.14 UTRAN Downlink Load Balance Threshold-Code


Parameter name UTRAN Downlink Load Balance Threshold-Code (%)

Abbreviated name

DlCdLdNeedBal2U

Description

This parameter indicates the downlink channellization code load balance threshold. If the local UTRAN cell’s downlink channellization code usage ratio exceeds the threshold indicated by this parameter, the downlink load balance judgment is performed and some UEs may be balanced to other UTRAN cell.


Unit %


50%

• OMC Path



Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->UTRAN Downlink Load Balance Threshold –Code(%)


This parameter indicates the load balance threshold of downlink code resources of a cell. If the downlink load exceeds the threshold indicated by this parameter, the downlink load balance judgment is performed and some UEs may be balanced to other UTRAN cell.

7.2.15 Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-Code


Parameter name Permitted Payload Difference Downlink Load Threshold in Inter-frequency Cells-Code (%)

Abbreviated name

ExtraCDeltaCdTrd

Description

This parameter indicates the downlink channellization code threshold for load balance between inter-frequency cells. When the local UTRAN cell’s downlink channellization code usage ratio exceeds the UTRAN Downlink Channellization Code Load Balance Threshold and the channellization code usage ratio difference of serving and target cell exceeds the threshold indicated by this parameter, the inter-frequency cell is a target cell satisfying the condition of load balance.


Unit %


10%

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Permmited Payload Difference Downlink Load Threshold in Inter-frequency Cells-Code(%)


This parameter indicates the code resource load difference threshold between inter-frequency cells. It is used to evaluate the load(Weight) of a cell as follows:

∑=

−−−=

k

1ii

i

iii Weight*Delta


Where,




DestLoad indicates the actual load of the target cell (the uplink interference is measured by RTWP; the downlink power is measured by CTCP; the downlink code resources are measured by the occupancy of SF = 128 code layer of non-HS-DSCH channels).






7.2.16 Service Balance Switch of Initial RRC Procedure


Parameter name Service Balance Switch of Initial RRC Procedure

Abbreviated name

InitRrcSBSw

Description This parameter is a service balance switch which indicates whether the RRC service balance function is open for initial RRC procedure used for accessing.


Unit N/A


0: Closed

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Service Balance Switch of Initial RRC Procedure


This parameter is a service balance switch which indicates whether the RRC service balance function is open for initial RRC procedure used for accessing.



7.2.17 Service Balance Switch of RAB Assignment Procedure


Parameter name Service Balance Switch of RAB Assignment Procedure

Abbreviated name

RabAssSBSw

Description This parameter is a service balance switch which indicates whether the load service function is open for RAB assignment procedure.


Unit N/A


0: Closed

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Service Balance Switch of RAB Assignment Procedure


This parameter is a load balance switch which indicates whether the load service function is open for RAB assignment procedure.

7.2.18 Service Balance Switch of Call holding procedureing Procedure


Parameter name Service Balance Switch of Call holding procedureing Procedure

Abbreviated name

CallHoldSBSw

Description

This parameter is a service balance switch which indicates whether load balance function is open for call holding procedureing procedure. The application scenes are including handover, relocation, RAB re-establishment and FACH->DCH.


Unit N/A


0: Closed

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Balance Information->Service Balance Switch of Call holding procedureing Procedure




This parameter is a load balance switch which indicates whether load balance function is open for call holding procedureing procedure. The application scenes are including handover, relocation, RAB re-establishment and FACH->DCH.

7.2.19 Preferred Traffic Type


Parameter name Preferred Traffic Type

Abbreviated name

PrefTrafType

Description

This parameter indicates which traffic type is preferred in the cell. CS service will be accessed the cell with attribute of “CS Preferred” , and PS Service will be accessed the cell with attribute of “PS Prferred”, and CS+PS service will be accessed the cell with attribute of “CS+PS Preferred”.

Range and Step

0: No Preference 1: CS Preferred 2: PS Preferred 3: CS+PS Preferred

Unit N/A


3: CS+PS Preferred

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Modify Advanced Parameter->Ultran Cell->Preferred Traffic Type


This parameter indicates which traffic type is preferred in the cell. CS service will be accessed the cell with attribute of “CS Preferred” , and PS Service will be accessed the cell with attribute of “PS Preferred”, and CS+PS service will be accessed the cell with attribute of “CS+PS Preferred”.

7.2.20 Share Cover Indication (utranRelation)


Parameter name Share Cover Indication (utranRelation)

Abbreviated name

ShareCover

Description This parameter describes the neighboring relationship of the serving cell and neighboring cell.



Range and Step

0: Neighbor 1: Overlap 2: Covers 3: Contained in

Unit N/A


0: Neighbor

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Neighboring Cell->Neighboring Cell XXX->Modify Advanced Parameter-> Share Cover Indication


This parameter describes the location of the serving cell and neighboring cell.

7.2.21 Share Cover Indication (gsmRelation)


Parameter name Share Cover Indication (gsmRelation)

Abbreviated name

GsmShareCover

Description This parameter describes the neighboring relationship of the serving cell and Gsm neighboring cell.

Range and Step

0: Neighbor 1: Overlap 2: Covers 3: Contained in

Unit N/A


0: Neighbor

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->GSM Neighbouring Cell->GSM Neighbouring Cell XXX->Modify Advanced Parameter-> Share Cover Indication


This parameter describes the location of the serving cell and Gsm neighboring cell.



7.2.22 HSPA Support Method


Parameter name HSPA Support Method

Abbreviated name

HspaSptMeth

Description This parameter indicates the support of DCH, HSDPA and HSUPA in the cell.

Range and Step

0: Not Support HSUPA and HSDPA 1: Support HSDPA and DCH 2: Support HSDPA only 3: Support HSUPA, HSDPA and DCH 4: Support HSUPA and HSDPA

Unit N/A Default Value (note) 3: Support HSUPA, HSDPA and DCH

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX->Cell Ability and Cell Reselection-> HSPA Support Method


This parameter indicates the support of HSPA in the cell.

7.2.23 Inter-RAT Downlink Load Balance Threshold-Power


Parameter name Inter-RAT Downlink Load Balance Threshold-Power (%)

Abbreviated name

DlLoadNeedBal2G

Description

This parameter indicates the downlink load threshold for load balance between different RAT systems. If the downlink load of the local cell exceeds the threshold indicated by this parameter, performs the downlink load balance judgment and UE of local cell may be balanced to other RAT systems.

Range and Step [0, 100]%, step 1% Unit %


58%

• OMC Path



Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX-> Modify Advanced Parameter -> Balance Information-> Inter-RAT Downlink Load Balance Threshold-Power(%)


This parameter indicates the downlink load threshold for load balance between inter-RAT. If the downlink load of the local cell exceeds the threshold indicated by this parameter, performs the downlink load balance judgment and UE may be balanced to inter-RAT cells.

The power threshold is higher than UTRAN Downlink Load Balance Threshold-Power (%) by default. That means, when the load balance is triggered by downlink power, the load is balanced to utran cells at first, and will not be balanced to inter-RAT cells until the downlink power increases and reaches to the threshold indicated by this parameter.

The higher the parameter value is, the smaller the possibility of that the services are balanced to inter-RAT cells.

And vice versa.

7.2.24 Inter-RAT Uplink Load Balance Threshold-Interference


Parameter name Inter-RAT Uplink Load Balance Threshold-Interference(dB)

Abbreviated name

UlLoadNeedBal2G

Description

This parameter indicates the uplink RTWP threshold for load balance between different RAT systems. If the uplink RTWP of local cell exceeds the threshold indicated by this parameter, performs the uplink load balance judgment and UE of local cell may be balanced to other RAT systems.

Range and Step (0.. 62) dB, step 0.1

Unit dB


20dB

• OMC Path

Path: View->Configuration Management->RNC NE->RNC Radio Resource Management->Utran Cell->Utran Cell XXX-> Modify Advanced Parameter -> Balance Information-> Inter-RAT Uplink Load Balance Threshold-Interference(dB)


This parameter indicates the uplink interference load threshold for load balance between different systems. If the uplink interference of local cell exceeds the threshold indicated by this parameter, performs the uplink interference load balance judgment and UE of local cell may be balanced to other systems.



The power threshold is higher than Inter-RAT Uplink Load Balance Threshold-Interference (dB) by default. That is, when the load balance is triggered by uplink interference, the load is balanced to utran cells at first, and will not be balanced to Inter-RAT cells until the uplink interference increases and reaches to the threshold indicated by this parameter.

The higher the parameter value is, the smaller the possibility of that the services are balanced to cells of other systems is. And vice versa.

8 Counter And Alarm

8.1 Counter List This feature has no relative counter.

8.2 Alarm List This feature has no relative alarm.

9 Glossary CS Circuit switched

HCS Hierarchical Cell Structure

HSDPA High speed downlink packet access

HSUPA High speed uplink packet access

PS Packet switched

RAB Radio access bearer

RNC Radio network controller

RRC Radio resource control

RSCP Received Signal Code Power

RTWP Received total wide band power

SF Spreading Factor

UE User equipment

UMTS Universal mobile telecommunication system

zte_umts load balance feature description

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