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Wcdma load sharing


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Wcdma load sharing

  2. 2. Copyright © Ericsson AB 2006 – All Rights Reserved Disclaimer No part of this document may be reproduced in any form without the written permission of the copyright owner. The contents of this document are subject to revision without notice due to continued progress in methodology, design and manufacturing. Ericsson shall have no liability for any error or damage of any kind resulting from the use of this document. 3/1553-HSD 101 02/6 Uen B 2009-01-20
  3. 3. Contents Contents 1 Introduction 1 1.1 Scope 1 1.2 Target Groups 1 1.3 Revision Information 1 2 Overview 3 2.1 Inter-Frequency Load Sharing 3 2.2 Directed Retry to GSM 4 3 Technical Description 5 3.1 Design concepts 5 3.2 Inter-Frequency Load Sharing 7 3.3 Directed Retry to GSM 9 4 Engineering Guidelines 13 4.1 Inter-Frequency Load Sharing 13 4.2 Directed Retry 13 5 Parameters 15 5.1 Description 15 5.2 Values and Ranges 15 6 Glossary 17 Reference List 19 3/1553-HSD 101 02/6 Uen B 2009-01-20
  4. 4. Load Sharing 3/1553-HSD 101 02/6 Uen B 2009-01-20
  5. 5. Introduction 1 Introduction 1.1 Scope This document describes the load sharing features available in the Ericsson WCDMA Radio Access Network (RAN). Acronyms and terms used in this document can be found in Glossary of Terms and Acronyms. Details about parameters used in Load Sharing can be found in Radio Network Parameters for P6.0 or Radio Network Parameters, RAN P6.1 for P6.1. Details about performance counters can be found in Radio Network KPI. 1.2 Target Groups This document is written for system operators. It is assumed that users of this document: • Are familiar with WCDMA basic knowledge. • Have a working knowledge of 3G telecommunication. Personnel working on Ericsson products or systems must have the training and competence required to perform their work correctly. 1.3 Revision Information The revision history for this description is listed in Table 1 on page 1. Table 1 Revision History Revision Reason for Revision A This is the first version for P6 based on 3/1553-HSD 101 02/4 . B Clarified interaction of Directed Retry with Service-Base Handover to GSM. 13/1553-HSD 101 02/6 Uen B 2009-01-20
  6. 6. Load Sharing 2 3/1553-HSD 101 02/6 Uen B 2009-01-20
  7. 7. Overview 2 Overview Load sharing enhances the performance of a Radio Access Network by pooling together resources from different parts of the entire network. Currently, two load-sharing features are available in the WCDMA RAN: • Inter-Frequency Load Sharing • Directed Retry to GSM Inter-Frequency Load Sharing diverts incoming traffic from a more loaded cell in one WCDMA carrier to a less loaded one in another WCDMA carrier. Directed Retry to GSM is a one-way diversion from WCDMA to GSM. They are illustrated in Figure 1 on page 3. Both features are implemented entirely in the RNC. carrier 2 WCDMA RAN GSM RAN Directed Retry to GSM Inter-frequency load sharing carrier 1 { Figure 1 Load sharing capabilities available in the WCDMA RAN. 2.1 Inter-Frequency Load Sharing Inter-Frequency Load Sharing improves the efficiency of a WCDMA RAN by pooling the resources of all the WCDMA carriers in use at a location. It will • provide a higher trunking efficiency, i.e., increase the ability of individual WCDMA cells to accommodate temporary fluctuations in an otherwise uniform traffic, • remove any long-term load-imbalance among the different carriers, and • provide a means to steer traffic from one WCDMA frequency to another in an asymmetric way. As a result, this feature will give a better utilization of the available spectrum and reduce the call-blocking probability. It also gives flexibility to network planning by removing load imbalance and by being able to steer traffic asymmetrically between frequencies. 33/1553-HSD 101 02/6 Uen B 2009-01-20
  8. 8. Load Sharing Idle state cell-reselection can also balance cell load to some extent. The 3GPP standard specifies two alternatives for selecting the best cell for a UE in the idle state (Reference [4]): the measured quality (Ec/N0) or the measured signal strength (RSCP) of the CPICH. In Ericsson systems, Ec/N0 is used. This indirectly takes into account the cell load. With Inter-Frequency Load Sharing, the cell load is measured directly in terms of the actual downlink power. A UE will be guided to the most suitable cell during the RRC connection establishment. 2.2 Directed Retry to GSM When there is a co-existing GSM RAN, excess traffic in a WCDMA cell may be off-loaded to GSM, with the following benefits. • It allows a WCDMA cell to handle more subscribers than it is dimensioned for, making it possible for the WCDMA RAN to be built out at a slower pace. • It allows the WCDMA RAN to focus on what it does best—to provide data services. • It makes it possible for the combined system to fully utilize the existing spectrum in GSM. Speech calls with no ongoing packet connections are considered for Directed Retry during RAB establishment. If the UE supports GSM handover and the load of the WCDMA cell exceeds a certain threshold, the WCDMA RAN will request a blind inter-RAT handover to a pre-configured GSM cell via the core network. The RAN operator has considerable control over this feature. Both the load threshold and the fraction of speech calls to be diverted to GSM are configurable. Note that when Service-Based Handover to GSM is enabled, speech calls may be handed over to GSM using Service-Based Handover. See Sec. 3.3 for details. 4 3/1553-HSD 101 02/6 Uen B 2009-01-20
  9. 9. Technical Description 3 Technical Description 3.1 Design concepts This section presents some of the design concepts common to both load-sharing features. 3.1.1 Cell load The load of a WCDMA cell depends on many factors, such as downlink power, uplink interference, code utilization, etc. For load-sharing purpose, only the downlink transmitted carrier power is considered since that is most often the limiting factor on the capacity of a cell. To better reflect the available resource in a cell, cell load is measured as the ratio between the downlink transmitted carrier power and the admission limit, as given by the cell parameter pwrAdm. For HSDPA cells, only the non-HSDPA part is counted, i.e., the cell load for load-sharing purpose does not include the power used for HS-PDSCH and HS-SCCH. The downlink transmitted carrier power for the non-HSDPA part is measured by the RBS and periodically reported to the RNC. An appropriately filtered value is provided by the Downlink Transmitted Carrier Power Monitor in the Capacity Management function (Capacity Management). This is also the same filtered value used in making admission-control and load-sharing decisions. 3.1.2 Source and target cells The cell that is making the load sharing evaluation will be called the source cell throughout this document. The intended destination of a redirection will be called the target cell. 3.1.3 Triggering of load sharing decisions In order to perform the necessary evaluation for making a load sharing decision, a cell has to be aware of the load of all of its load-sharing neighbors. The cost for making this decision must be kept low in order not to offset the benefit gained from load sharing. Once the UE has gone into soft handover the uncertainties in the location and cell preference of the UE become bigger, and measurement reports from the UE are needed to determine the load sharing target. For this reason both load-sharing features redirect calls during the connection setup phase when the cell-preference of the UE is obvious. Inter-Frequency Load Sharing is performed during the RRC connection establishment procedure and Directed Retry to GSM during the RAB establishment procedure. Details of these two procedures can be found in Connection Handling. 53/1553-HSD 101 02/6 Uen B 2009-01-20
  10. 10. Load Sharing Note that speech calls are subject to both Inter-Frequency Load Sharing and Directed Retry to GSM. Since the RRC connection establishment procedure takes place well before RAB establishment, there is no inter-operability issue between the two load sharing features. It is possible, however, for a speech call to be first directed from one WCDMA frequency to another and then further redirected to GSM later. Whether that would happen depends on the cell load and the parameter setting at the time. 3.1.4 Co-located cells Since the redirections are made without UE measurements, they are blind redirections, and are, therefore, made only between co-located cells. Co-located cells are assumed to provide very similar coverage and accessibility in the same geographical areas. Typically, they serve the same sectors and share the same antenna positions. For Directed Retry to GSM, it is assumed that the WCDMA RAN is co-sited with the GSM RAN and a one-to-one correspondence between WCDMA cells and GSM cells exists in all load sharing situations. Occasionally there will be mismatch in the coverage between co-located cells due to cell tuning or border effects. One example is shown in Figure 2 on page 6. Because of the lack of co-channel interference from outside the border, a border cell such as B2 can provide much larger coverage in the outward direction. Unless carefully tuned, there can be a significant mismatch in coverage between two co-located cells such as B1 and B2 in the figure. T2 8s 12 :35 A1B1D1 C1 A2B2 Figure 2 Example of coverage mismatch between co-located cells near a carrier boundary. Layer 2 (with cells A2, B2) depicts one carrier in the WCDMA RAN. Layer 1 (with cells A1,..., D1) depicts either another WCDMA carrier or a co-sited GSM RAN. As illustrated in Figure 2 on page 6, when a UE located well inside the cell C1 tries to make a call, it may access the network through the cell B2. If B2 decides to redirect the call to its co-located neighbor B1, the access could fail because there is no coverage from B1 for the UE. This situation is carefully handled in both load-sharing features and is described in the respective sections below. Moreover, if the UE retries in the original cell (B2), the system would ensure that the connection is set up in the cell and not redirected again. 6 3/1553-HSD 101 02/6 Uen B 2009-01-20
  11. 11. Technical Description 3.2 Inter-Frequency Load Sharing 3.2.1 Description Inter-Frequency Load Sharing attempts to divert incoming traffic (both circuit- and packet-switched) during RRC connection establishment from a more-loaded cell to a less-loaded one at the same location but on another frequency. For load-sharing purpose, the total resource of a cell is the fraction of the total transmission power up to the admission limit as given by the cell parameter pwrAdm). Load-sharing decisions are made based on the amount of remaining resource in the cell. Part of the total resource can also be excluded from load-sharing use, giving remaining-resource = 1 – cell-load – excluded-resource, where cell load is as defined above in Section 3.1.1 on page 5. Inter-Frequency Load Sharing tries to balance the remaining resource among the load-sharing neighbors. Cells with excluded resource appear to be more loaded (i.e., less remaining resource) than they really are, resulting in more traffic being directed away from them. In the case of an HSDPA cell co-locating with a non-HSDPA cell, this can be used to reserve a specific amount of the DL carrier power in the HSPDA cell for HS traffic. The actual redirection is accomplished using the redirection mechanism of the RRC Connection Reject message (see Reference [5]). First, an evaluation is made based on a comparison of the remaining resources of the co-locating load-sharing neighbors. If a redirection is to be made, the cell with the most remaining resource will be chosen as the target. The UE will, however, not be instructed directly to go to the target cell. Instead, it will be told to scan for a suitable cell in the frequency of the target cell. This is achieved by sending an RRC Connection Reject message in response to the UE's request. The message carries a Redirection Info Information Element that tells the UE to try to access the network via a specific frequency. The intention is to avoid the coverage mismatch situations discussed earlier by not forcing the UE to go to a specific cell. Note that if a loadsharing decision results in sending a call to a cell with no remaining-resource (i.e., with a zero or negative value), a new decision will be made with the excluded-resource term removed for all load-sharing neighbors. One purpose of this reconsideration is to avoid situations where a call would be rejected by an overloaded cell because its lightly-loaded load-sharing neighbor cannot accept the call due to a large excluded-resource. If the UE has chosen a cell different from the intended target, that cell may or may not have a larger remaining resource since it was not involved in the load sharing evaluation. This happens most often when the UE is straddling the boundary between two cells and it makes little difference to the UE whether it selects the cell on one side or the other of the boundary. To avoid endless back-and-forth redirections, a UE will always be set up in the cell of the second 73/1553-HSD 101 02/6 Uen B 2009-01-20
  12. 12. Load Sharing access attempt, regardless of the resource situation. The UE could also have returned to the source cell if it has failed to gain access to the target frequency or it has no support for RRC-redirections. In the latter case, the UE would not be 3GPP-compliant. Note that the second access attempt is subject to normal admission control, like any other call. (Note: If the UE is rejected by admission control in the target cell, it may perform a cell reselection back to the source cell, but in this case, the target cell would be the serving cell and enjoys an advantage over the source cell by the amount of the cell-reselection hysteresis margin. If the UE succeeds in reselecting the source cell, further load sharing redirections are possible.) A second type of back-and-forth redirections occurs due to cell-load fluctuations, e.g., when cell A sends a call to cell B, and cell B (after accepting the redirected call) immediately sends its next incoming call to cell A. Both of these redirections are obviously not necessary. The two cells are better off just keeping their own calls. An internal redirection margin is used to cut down on this kind of redirections. The size of this margin is related to the size of the fluctuations in downlink cell power and the filtering being used. Note that the fluctuations in downlink cell power depend not only on the fluctuations in traffic but can also be influenced by UE behaviors. Typical value of this margin is on the order of 10% of the admission limit (as given by the parameter pwrAdm in Capacity Management). Note that it is desirable to keep this margin even when both the source and target cells are very heavily loaded for the following reasons: (1) The fluctuations in downlink cell power is not expected to decrease with increasing cell load. (2) Cutting down on unnecessary redirections becomes more important when a cell is heavily loaded. In contrast, load-sharing redirections are not really needed when a cell is only lightly loaded. Processing power for making the load sharing evaluations are usually pooled over many cells. If saved, this power can be diverted for use in the more heavily loaded cells. For this reason, a load threshold is used to suppress the redirections at low load. This threshold is fixed at 50% of the admission limit. This value is chosen as a compromise between the need for load sharing and the cost for making a load-sharing evaluation. 3.2.2 Configuration This feature is activated in an RNC by setting the parameter loadSharingRrcEnabled to TRUE. Load-sharing neighbors must be defined before any load-sharing action can take place. They are specified via the usual neighbor-cell relations. Each relation for a source cell has a target cell and a number of other attributes. The attribute loadSharingCandidate specifies whether the target cell is a load-sharing neighbor of the source cell. The neighbor-cell relation must be created first if it does not already exist. Possible values for loadSharingCandidate are TRUE and FALSE. For Inter-Frequency Load Sharing to work properly, there should be no more than one neighbor per carrier for each source cell, and all load-sharing neighbors should be co-located. Note that this is assumed but not enforced in the configuration of loadSharingCandidate. Care must be taken to ensure that load-sharing neighbors are defined correctly. 8 3/1553-HSD 101 02/6 Uen B 2009-01-20
  13. 13. Technical Description Note 1: Because of the co-location requirement, load-sharing neighbors are assumed to be served by the same RBS. Load sharing between cells served by different RBSs (even if they are co-located) are not allowed, and attempts to configure such neighbors will fail. Note 2: This feature uses the same neighbor-cell relations as Inter-Frequency Handover. If a relation is created for Load Sharing purpose but not wanted by Inter-Frequency Handover, the handover can be suppressed by setting the cell parameter hoType to NONE or GSM_PREFERRED. For details of how this parameter works, see HandoverHandover and Radio Network Parameters for P6.0 or Radio Network Parameters, RAN P6.1 for P6.1. 3.2.3 Operation Inter-Frequency Load Sharing can be turned off on a cell-by-cell basis by removing all load-sharing neighbors of a cell, i.e., by setting the loadSharingCandidate attribute to FALSE in all neighbor-cell relations for that cell. The amount of resource excluded from load-sharing use is specified by the cell parameter loadSharingMargin as a percentage of pwrAdm. The performance of Inter-Frequency Load Sharing can be monitored via the following three counters (see also Radio Network KPI): • pmTotNoRrcConnectReq gives the total number of RRC connection requests in a cell. • pmNoLoadSharingRrcConn gives the number of RRC redirections performed for load-sharing reason in a cell. • pmNoOfReturningRrcConn gives the number of calls that has returned to the original frequency after an RRC-redirection. (Note that this counter is incremented in the cell to which the UE returns, and the UE may occasionally return to the same frequency but not to the original cell.) The redirection intensity and success rate can be obtained from the ratio of these counters. 3.3 Directed Retry to GSM 3.3.1 Description Directed Retry to GSM attempts to off-load traffic from the WCDMA RAN to a co-sited GSM RAN. Speech call that has no ongoing packet connection is the only service that is targeted since it is also the only one that is safe to divert to GSM. The decision is triggered by a RAB Assignment Request from the core network. This message contains the information needed to identify the call as a speech-only call. Incoming calls are screened for suitable candidates according to the following criteria. 93/1553-HSD 101 02/6 Uen B 2009-01-20
  14. 14. Load Sharing • The call is a speech-only call with no ongoing packet connection. • The UE can be handed over to GSM. If a call is chosen for Directed Retry to GSM, the request for the speech RAB will be rejected with cause “Directed retry” and then a request is made to the core network to relocate the UE to a specific GSM cell, using the Inter-RAT handover procedure (Handover). This handover is a blind one since the target cell is chosen not based on UE measurements. Therefore, the target cell must be co-located with the WCDMA cell. Co-located GSM cells are assumed to have similar coverage and accessibility as their respective WCDMA cells. As illustrated in Figure 2 on page 6, coverage mismatch near the boundary of the WCDMA RAN (and those due to blind spots in the GSM cell) can sometimes be a problem for blind redirections. A UE returning after failing the access to GSM will be reported to the core network, which would reinitiate the RAB establishment procedure on behalf of the UE. A speech RAB will then be set up for the UE in the WCDMA RAN following the normal call setup procedure. When to begin off-loading and how much traffic to send over to GSM can be configured via two control parameters. They are described in the operation section below. Selective handover (Handover) in a shared-network environment is not currently supported by the Directed Retry to GSM feature. Off-loading to GSM will be attempted as long as a Directed Retry target is defined. There is no guarantee, however, that the UE will be allowed in the target cell. With the introduction of Service-Based Handover to GSM, the responsibility of Directed Retry has changed. How and whether a call can be handed over to GSM is determined from the RANAP Information Element (IE) Service Handover received from the Core Network during call setup. This IE has 3 values: Handover to GSM should, should not, and shall not be performed. It is handled as follow: Shall not Never handed over to GSM. Should not Only when losing coverage. Should Handed over via Service-Base Handover. If Service-Based Handover is not enabled, the call is considered by Directed Retry instead. IE is missing The call is considered by Directed Retry. 3.3.2 Configuration Directed Retry to GSM is activated in an RNC by setting the flag loadSharingDirRetryEnabled to TRUE. One GSM target can be defined for each WCDMA cell via the cell parameter directedRetryTarget. Care must be taken to ensure that the correct GSM targets have been defined and that they are indeed co-located with their respective source cells in the WCDMA RAN. 10 3/1553-HSD 101 02/6 Uen B 2009-01-20
  15. 15. Technical Description 3.3.3 Operation There are two control parameters for this feature: • loadSharingGsmThreshold specifies the minimum cell load at which off-loading to GSM begins. Remember from Section 3.1.1 on page 5 that cell load is expressed as the radio of the downlink transmitted power to the admission limit (pwrAdm). This threshold is expressed as a percentage rather than a fraction. A value of 0 means the feature is always on, 100 means it is always off, and 50 means off-loading starts as soon as the cell load rises above 50% of the admission limit. (Note also that there is an idle load in each cell due to the various common channels.) Example: The parameter pwrAdm is expressed as a percentage of the maximumTransmissionPower. In the default setting where maximumTransmissionPower = 370 dBm (5 W) and pwrAdm = 75%, a value of 80% for loadSharingGsmThreshold means off-loading will start when the carrier power of the cell is above 5 W × 0.75 × 0.80, or 3 W. • loadSharingGsmFraction specifies the percentage of Directed Retry candidates to be diverted to GSM while the cell load is above the specified load threshold. A value of 0 means no diversion will take place and a value of 100 means all calls qualified for Directed Retry will be diverted. Both of these parameters are cell-specific so that different values can be chosen to suit the needs of different cells. Note that no call will be diverted from a WCDMA cell unless all of the following criteria are met. 1 The RNC-wide flag loadSharingDirRetryEnabled is set to TRUE. 2 A GSM target has been defined. 3 The parameter loadSharingGsmThreshold is set to a value below 100. 4 The parameter loadSharingGsmFraction is set to a value larger than 0. The preferred way to temporarily turn off Directed Retry in a cell is to set loadSharingGsmFraction to exactly 0. Note also that a WCDMA cell makes the decision to send a call to GSM without knowledge of the load situation in the GSM target cell. Overloading of the target cell can occur. The parameters loadSharingGsmFraction and/or loadSharingGsmThreshold can be used to limit the amount of speech calls going to GSM. The success rate can be monitored by two counters (see also Radio Network KPI): • pmNoDirRetryAtt gives the total number of Directed Retry attempts. • pmNoDirRetrySuccess gives the number of successful attempts. 113/1553-HSD 101 02/6 Uen B 2009-01-20
  16. 16. Load Sharing Note that unsuccessful attempts are picked up by the WCDMA RAN if the call returns to the source cell. The call will then be set up according to the normal call-setup procedure. Finally, careful planning is recommended if this feature is to be used concurrently with others that are capable of sending traffic from GSM back to the WCDMA RAN because of the risk of back-and-forth redirections. 12 3/1553-HSD 101 02/6 Uen B 2009-01-20
  17. 17. Engineering Guidelines 4 Engineering Guidelines 4.1 Inter-Frequency Load Sharing 4.1.1 Deployment of a second frequency During the initial deployment of a second frequency, there may be problems in accommodating older UEs that do not fully support Inter-Frequency Handover. One solution is to have all UEs camping on the first frequency and use IFLS to populate the second. See the Engineering Guideline section in Idle Mode and Common Channel Behavior and Handover for details. 4.1.2 Multi-band operation In networks operating in a multiple frequency band environment, it is possible for a multi-carrier RBS to have co-located cells operating in different frequency bands. If not all UEs in the network are capable of all frequency bands, redirection of a call to a frequency band not supported by the UE may lead to some problem. In the case of Inter-Frequency Load Sharing, redirections are done using RRC Connection Reject, and the system does not have any information on UE capability at that time (a UE will only send up its capability after the system has accepted the RRC Connection Request). If IFLS neighbors belonging to different bands are configured and the load condition is right, single-band UEs can be redirected to an unsupported frequency band. The consequence would be a roughly 1-sec delay in the call setup, i.e., the UE does not recognize the UARFCN specified in the Frequency Info and waits out the "Wait time" before attempting a second RRC Connection Request. If this is considered to be a serious problem, one solution is to avoid defining IFLS neighbors between cells operating in different bands and rely on Idle Mode Cell Reselection to balance the load in those cells. 4.2 Directed Retry If inter-system handover from GSM to WCDMA is enabled because of coverage reason, care should be taken to ensure that the parameter MRSL is not set too low. Otherwise, calls off-loaded to GSM via Directed Retry may return to the WCDMA RAN. Handover from GSM to WCDMA for load reason is generally not recommended if Directed Retry is enabled in the WCDMA RAN. See also the Engineering Guideline section in Handover. 133/1553-HSD 101 02/6 Uen B 2009-01-20
  18. 18. Load Sharing 14 3/1553-HSD 101 02/6 Uen B 2009-01-20
  19. 19. Parameters 5 Parameters This section describes the parameters that the operator can configure to control the WCDMA RAN Load Sharing features. For recommended values and other details, see Radio Network Parameters for P6.0 or Radio Network Parameters, RAN P6.1 for P6.1. 5.1 Description 5.1.1 Inter-Frequency Load Sharing loadSharingCandid ate A UtranRelation attribute that indicates if a target cell is a load sharing neighbor of the source cell. loadSharingMargin A cell-specific parameter that specifies the amount of resource excluded from load-sharing use. loadSharingRrcEn abled An RNC-wide flag for turning on the feature. 5.1.2 Directed Retry to GSM loadSharingDirRetr yEnabled An RNC-wide flag for turning on the feature. directedRetryTarg et A cell-specific parameter that specifies the Directed Retry target in terms of a cell reference to an external GSM cell. loadSharingGsmT hreshold A cell-specific parameter that specifies the load threshold below which Directed Retry to GSM is suppressed. loadSharingGsmFr action A cell-specific parameter that specifies the fraction of qualified speech calls to be diverted to GSM. 5.2 Values and Ranges Table 2 on page 15 summarizes the parameters mentioned in this document. Table 2 WCDMA RAN Load Sharing Parameters Parameter Name Default Value Value Range Resolution Unit Inter-Frequency Load Sharing 153/1553-HSD 101 02/6 Uen B 2009-01-20
  20. 20. Load Sharing Table 2 WCDMA RAN Load Sharing Parameters Parameter Name Default Value Value Range Resolution Unit loadSharingCandidate FALSE (FALSE; TRUE) - - loadSharingMargin 0 0..100 1 % of pwrAdm loadSharingRrcEnabled FALSE (FALSE; TRUE) - - Directed Retry to GSM loadSharingDirRetryEna bled FALSE (FALSE; TRUE) - - directedRetryTarget 'empty' External GSM cell reference - - loadSharingGsmThreshold 75 0..100 1 % of pwrAdm loadSharingGsmFraction 100 0..100 1 % 16 3/1553-HSD 101 02/6 Uen B 2009-01-20
  21. 21. Glossary 6 Glossary All acronyms and terms used in this document can be found in Glossary of Terms and Acronyms. 173/1553-HSD 101 02/6 Uen B 2009-01-20
  22. 22. Load Sharing 18 3/1553-HSD 101 02/6 Uen B 2009-01-20
  23. 23. Reference List Reference List [1] Glossary of Terms and Acronyms, 1/0033-HSD 101 02/6 [2] Radio Network Parameters, 86/1553-HSD 101 02/6 [3] Radio Network KPI, 120/1553-HSD 10102/6 [4] UE Procedures in Idle Mode and Procedures for Cell Reselection in Connected Mode, 3GPP TS 25.304, Rel. 5 [5] RRC Protocol Specification, 3GPP TS 25.331, Rel. 5 [6] Connection Handling, 4/1553-HSD 101 02/6 [7] Handover, 76/1553-HSD 101 02/6 [8] Capacity Management, 83/1553-HSD 101 02/6 [9] Idle Mode and Common Channel Behavior, 71/1553-HSD 101 02/6 193/1553-HSD 101 02/6 Uen B 2009-01-20