3G Handover parameter optimization October 2013
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Mobility Robustness Optimization versus Handover Optimization Mobility Robustness for LTE: • Target to prevent too early/too late HOs and ping pong • By optimizing the handover parameters for execution criteria Mobility Robustness for WCDMA • Target to prevent too early/too late HOs and ping pong • pec e n as unct ona ty or s • For WCDMA intra-frequency soft handover and hard handover • For WCDMA inter-frequency and inter-system hard handovers • Has been available since early days of WCDMA, even not called as Mobility Robustness Optimization • The same as LTE MRO is not needed for WCDMA any more Currently there are other reasons for optimizing handover settings for WCDMA For internal use Unique document identifier (ID) / Version number / Life cycle status
Motivation to pay attention to 3G HO parameters 1) Need to make the current neighbors to work better •
When optimizing 3G neighbors very often the conclusion after identified the poor neighbors is to keep them but to optimize the behavior • •
Increase the amount of handovers Improve handover performance • •
2
By optimizing radio conditions Or by optimizing handover parameter settings
Need to ensure data call performance also through cell-reselection •
Different re-selection criteria are applied for different types of cells and handover directions
3) Need to managing the traffic steering in overlapping network layers •
In order to maximize the utilization of network resources or use them according to operator strategy, there is a need to control what traffic is served in each layer and how • •
Need to optimize UE handling in idle and connected mode Need to optimize handover triggering criteria
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Full process for handover optimization available NetAct Optimizer current release supports WCDMA HO optimization process • Actual network situation can be easily analyzed in one view • Overlapping cell layers and neighbors, from different vendors • Performance of cells and neighbors can be viewed or automatically analyzed
• KPI analysis Traffic in classes, HO statistics • Cell pair level signal overlap analysis • Geo-KPI analysis for area troubleshooting • Current HO settings
• Neighbor relations can be optimized • Creation, deletion, list length optimization for all neighbor types based on measurements
• Radio conditions can be optimized • Signal overlap situation can be improved to enable successful handovers
• Handover parameters can be manually modified For internal use Unique document identifier (ID) / Version number / Life cycle status
Automated WCDMA Handover optimization An optimization algorithm added in NetAct Optimizer to • Identify the WCDMA intra-frequency and inter-frequency neighbors where handover performance is not on target level • Clarify the root cause for the poor handover performance • Propose better parameter values for handover triggering
Algorithm considers both speech and data calls separately Visual methods enhanced to evaluate the
Optimizer functionality is controlled via SON Operations Manager to enable highly automated process • Triggering criteria for algorithm execution can be set • Ability to control the execution order of the alternative algorithm • E.g. whether poorly working neighbors are deleted or if they are optimizer
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Controlled Traffic Steering in Heterogeneous Networks October 2013
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Operator strategies/targets with multiple overlapping radio networks Most of the operators have radio network from multiple vendors and multiple technologies covering the same area • GSM 900 and GSM1800 • WCDMA several frequencies • LTE spots or seamless coverage • Large umbrella cells, small micro cells, even pico cells and femto cells…
Via the overlapping coverage they are usually targeting to • Seamless coverage • Adequate capacity in general • Adequate capacity for specific value added traffic (services, subscribers) Operator strategies in investing on all the layers and using these are very different In order to use the investment according to strategy it must be possible to monitor and control on how the traffic is moved across the network layers For internal use Unique document identifier (ID) / Version number / Life cycle status
Traffic Steering layers Management of Traffic Steering
Service Mgmt • The service and subscriber dimension, QoE
M o n i t o r
C o n t r o l
Service Mgmt O p t i m i z e
Resource Mgmt utomat on
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Resource Mgmt • Monitor NW QoS, usage and capacity • Control the confi uration of network •
radio 2G
core macro
3G LTE
Small cells
transport
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Control from the service layer, e.g. policies, subscriptions, …
traffic steering functionalities for desired outcome, e.g. priorities Optimize the relevant parameters, e.g. triggering thresholds, …
Network functionalities • Steering of traffic to the desired layers • Based on e.g. priorities, services, UE,
•
coverage and load • Requires control Distributed functions and intelligence
Traffic Steering in heterogeneous networks •Traffic steering targets in load balancing and improving the subscriber performance by forwarding the traffic efficiently between the network layers based on available information − − − − − −
UE / network capability Requested service, QoS/QoE KPIs, QoS differentiation Cell load Power consumption in UE and BTS UE measurements UE s eed and mobilit
Traffic steering in idle mode
Traffic steering in connected mode
• Direct idle devices to the preferred active state use layer to avoid unnecessary handovers and pingpong for improved network service quality • Layer selection is steered by adjusting measurement rules, cell reselection priorities, thresholds and offsets • Criteria for layer selection: device capability and penetration, UE velocity and cell load
• Pushing the active calls to the appropriate layer according the session characteristics and network capability • Layer change is usually based on handover and cell reselection criteria • Criteria for layer selection: used services, UE velocity, UE and network capabilities matching, load in source and target cells, signal strength
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Traffic Management functionality for Optimizer Traffic management starts by seamless analysis of the network and traffic conditions – All radio technologies and inter-system traffic – Traffic class analysis in each geographical area – All relevant domains like radio and transport
Traffic management functionality is handled in two levels 1. Target behavior setting by optimizing idle mode parameters – – –
2.
To ensure the right types of calls are activated in the right network layer User controlled adjustment for the cell selection criteria Algorithm analyses the network based on statistics and according the given control criteria sets the optimal parameters
Traffic management principles for active calls – To help network elements to execute traffic steering according to operator strategy – Adjustments for Handover or cell reselection criteria are made based on network performance and given control criteria
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Traffic Management capabilities in Optimizer today NetAct Optimizer in OSS5.3 releases onwards provides a good base line for managing the traffic steering in multi-radio network Complete view to all overlapping network layers • Optimizer provides one view to see 2G,3G and LTE network of any vendor • Network settings like neighbors or performance like traffic can be presented in the common view
Means to analyze the capacity utilization from end to end • Optimizer provides automated functionality to check the capacity bottlenecks in •
the network now or near future In radio and transmission domain
Means to adjust the traffic steering related parameters manually • In the current Optimizer the changes to parameters can be done manually and provisioned automatically For internal use Unique document identifier (ID) / Version number / Life cycle status
Balancing traffic load between GSM & WCDMA in a capital area The problem of one of the leading operators in Europe was to balance the load between GSM and WCDMA NetAct Optimizer was used to analyze the network behavior in both layers • Problematic cells were identified using the data provided in Optimizer •
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Measurement based signal overlap and interference •
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neighbors, handover attempts, traffic in cells and handovers
signal strength and quality measurements from UEs, propagation delay, timing advance
Identification and elimination of the overshooting signals executed ”We met the target. The network was clearly stabilized and forced handover amount decreased. Optimizer provides unique visibility and easy analysis of WCDMA behavior” For internal use Unique document identifier (ID) / Version number / Life cycle status
Analysis of an interferer: RSCP Threshold > -95, Distance >1km prioritized with number of interference samples Problematic cells are ones with most measured interference pairs
