Chapter 18. xACP Optimization
In this section, we will learn how to use the xACP optimizer. So far, we have discussed how to build an ACP PRJ in terms of the required network specific inputs. Here, we will look at the PRJ details as they apply to the optimization process. This section is divided into the following sub-sections:
Preparing for Optimization: Input data validation, optimization targets/thresholds, cell-level optimizer configuration
Running the Optimization: Network-level optimizer configuration including RF parameters, traffic type(s), budget constraints, and optimization weights.
18.1. Preparing for Optimization
18.1.1. Input Data Validation
Before running the optimization process, it is very important to validate the accuracy of the ACP PRJ input data. The most important part of any xACP project is a complete and accurate set of data. While the users can check and validate the data in any order, the following sequence is recommended.
ACP Consistency Check
Once project import is complete the user should utilize the ACP Consistency Check to aid in verifying a complete project. ACP Consistency Check is invoked by selecting x-ACP > Consistency Check. As seen in Figure 18.1, “ACP Consistency Check - Physical Tab”, Figure 18.2, “ACP Consistency Check - Prediction Tab”, and Figure 18.3, “ACP Consistency Check - UMTS Tab”, the xACP consistency check is broken into three categories with several checks in each category as follows:
1. Physical
a. Loaded Antenna Pattern - Checks that each sector has a valid antenna pattern assigned.
b. Antenna Pattern Validity - Checks the validity of each antenna pattern by detecting if the horizontal or vertical patterns have multiple consecutive blank entries or 0 values. Mulitple consecutive blank entries or 0 values in the horizontal or vertical antenna pattern does not always mean the antenna pattern is bad but those with this issue should be checked via Edit > Antenna and viewing the pattern.
c. Ground Elevation - Checks for the existence of ground elevation data for all sectors in the project greater than a user defineable value.
d. Pa Power - Checks that PA power is greater than a user definable value.
e. Mechanical Tilt between - Checks that mechanical tilt is between two user defined values.
f. Antenna Height between - Checks that antenna height is between two user defined values.
g. Electrical Tilt between - Checks that electrical tilt is between two user defined values. Incorrect ET values in antenna patterns are very common.
h. Azimuth Sanity - Identifies sectors that belongs to same site and Tech-Band that are close or same in Azimuth
2. Prediction
a. Sector missing Pathloss - Checks that every sector has an associated pathloss grid. Since antenna patterns are used to calculate pathloss when pathloss is not available from the prediction tool (ASSET, PEV, Atoll, etc), this can be a result of incorrect band or missing antenna as well as the pathloss/RSSI file not present for import.
b. Sector missing RSSI - Checks that every sector has an associated RSSI grid. Possible reasons for missing RSSI grids include: missing pathloss grid, RSSI Deleted or not generated (can be generated on demand via x-Propagation menu).
c. Sector has number of Best Server pixels < - Checks if any sector has a number of best served pixels less than a user defined value.
d. Sector has number of Drive Data points < - Checks if any sector has a number of drive data points less than a user defined value. If drive data is not imported, every sector will fail this test.
e. Sector Pixel Confidence - Checks that pixel confidence (Predictions vs. Drive Measurements - See the section called “Pixel Confidence Report”) mean delta is greater than 6 dB or standard delta is greater than 8 dB.
3. UMTS
a. UMTS Parameters - Checks that Max. PA Power, CPICH Power, SCH Power, PCCPCH Power, SCCPCH Power, Noise Rise, Max. Noise Rise, Percentage of Loading, and Bad Erlang are within a user-defined range.
b. Simulation Profile Existence - Checks that at least one Circuit Switched and one Packet Switched UMTS Simulation Profile exists. It is very important that the project contains an accurate representation of the on-air UMTS service mix.
c. RAB Power Consistency - The higher the bit rate, the more power is needed to achieve it at a reasonable BLER (Eb/No). Checks that RAB powers are as follows:
Chapter 18. xACP Optimization
Table of Contents
18.1. Preparing for Optimization 18.1.1. Input Data Validation 18.1.2. Network Data Validation 18.1.3. Using Groups in ACP 18.1.4. Save Project for Optimization 18.1.5. Configuring Optimizable Parameters 18.1.6. Configuring the ACP Optimizer 18.1.7. Candidate Site Creation (GSM only) 18.1.8. Running the Optimizer
i. Bit Rate <= 12.2k, RAB power >= -3 dB (relative to CPICH)
ii. 12.2k < Bit Rate <=128k, RAB power >= 3 dB (relative to CPICH)
iii. Bit Rate > 128k, RAB power >= 6 dB (relative to CPICH)
Figure 18.1. ACP Consistency Check - Physical Tab
Figure 18.2. ACP Consistency Check - Prediction Tab
As seen in Figure 18.4, “ACP Consistency Check - OLAP Output” results are presented in OLAP view for ease of viewing.
Figure 18.4. ACP Consistency Check - OLAP Output
Path-loss/RSSI Validation
Display the RSSI spatial view for the entire network. This is the position-based received signal information that we imported either using the DM or the prediction PLOSS files. The RSSI can be displayed by first selecting the desired Tech/Band to be viewed in the Tech/Band Filter and then selecting Raster > RF > Measurements and Predictions > RSSI from the Layer Manager Display Tree as shown in Figure 18.5, “RSSI Display for All Cells in the Network”. For dual tech/band PRJs, view each tech/band individually by selecting the appropriate option from the Tech/Band Data Filter drop-down list.
One or more cells can be selected or deselected by holding the CTRL key and clicking the left mouse button. If no cell is selected (e.g. clicking on the space between cells), then the entire data will be displayed as shown in Figure 18.5, “RSSI Display for All Cells in the Network”.
Figure 18.6. RSSI Display for Selected cells Only
Note
It is very important to click on a few cells and display their individual RSSI view one-at-a-time. This is to make sure that the PLOSS data is mapped to the correct cell, as shown in Figure 18.6, “RSSI Display for Selected cells Only”.
Important
When the user selects one sector for RSCP visualization xACP will use the prediction information for the sector for the display. When the user selects more than one sector xACP will use the N-Best analysis and display for each sector information based on the N-Best analysis. Based on the “N” selected by the user for the N-Best analysis, the information displayed in this case will vary. The larger the “N” selected by the user, the more information will display when more than one sector is selected.
The user should also verify that Best Served areas appear to be realistic by using the “Color Pixels By Best Server” display as seen in Figure 18.7, “Map colored by best server”.
Figure 18.7. Map colored by best server
Pixel Information
The user may view detailed pixel information by selecting View > Spatial > Pixel Information or by simpling selecting the Pixel Information tool in the toolbar. As seen in Figure 18.8, “Pixel Information GIS Display” the user is presented with detailed Pixel Information. The Pixel Information display is capable of both a Dynamic and Static mouse mode. The top “x” readings for the pixel selected are displayed with the best RSSI for the
pixel selected displayed closest to the cursor and others displayed successively further away from the cursor according to RSSI. The “x” number of Best Servers to display can be set in Tools > Options, Visualization tab (see Section 17.3.3, “Options”). Latitude, Longitude, Terrain Elevation, Clutter Description, and Traffic Demand are also displayed if the rasters are selected in the Layer Manager. A line is also displayed pointing to the serving sector and colorized according to n-best server.
Figure 18.8. Pixel Information GIS Display
Pixel Confidence Report
If drive measured data has been imported into the project, the user should utilize the Pixel Confidence Report to understand the error between driven and predicted data that has been imported. For a given sector the set of all pixels that belong to that sector and analyzed. Pixel confidence is computed for each pixel on a scale from 0 to 100. The sector confidence is the percentage of pixels with good confidence. The pixel confidence is computed by computing the absolute error between drive data and prediction data for each pixel and then weighting it by the prediction RSSI at that pixel. The confidence of drive data at a given pixel is very low if the error between drive data and predicted data is high and prediction is high.
The Pixel Confidence Report can be accessed by selecting x-ACP > Reports > Generate Pixel Confidence Report. When this menu choice is invoked the user is presented with a dialog wherein a Measured/Predictions Data Filter and a Confidence Threshold can be selected. See Figure 18.9, “Pixel Confidence Report Dialog”.
Figure 18.9. Pixel Confidence Report Dialog
If the “Filter Report by Threshold” check box is checked pixel confidence algorithm will eliminate pixels for which the pixel confidence is less the threshold translated. This has the effect of eliminating sectors with poor pixel confidence from the report. Reports are presented when the generation completes and can be viewed via View > OLAP Reports > ACP > Pixel Confidence Report.
1. Project_name.sector_confidence.txt - This file contains each sector that has both predicted and drive measured data, the number of driven pixels associated with that sector, the mean delta between the driven and predicted bins, the standard delta between the driven and predicted bins, and the calculated confidence level for that sector. See Figure 18.10, “ Pixel Confidence OLAP Report”.
2. Project_name.no_readings.txt - This file contains a list of sectors for which no drive measured data was found.
3. Project_name.no_predictions.txt - This file contains a list of sectors for which no predicted data was found.
Physical Data Validation
Next, display the cell level physical parameters by selecting Edit > Sector (Physical Tab) as shown in Figure 18.11, “Validating the Physical Parameters”. The ESD contains the hard and soft parameters for every cell in the network. These parameters can be modified through the GUI for each cell individually, for a cluster of cells, or globally (Select All). Note, only a single cells information can be displayed at a time. If multiple cells are selected, only parameters that are same for all selected cells will be populated (viewable).
In this section, we will validate the following:
Status: Defaults to On Air. See Section 18.1.5, “Configuring Optimizable Parameters” for more details.
Lat / Long: The geographical location of the selected cell
Ground Elevation: The height above sea level of the selected cell
Antenna Model: The antenna model (also called the Antenna Family) used at the selected cell
Antenna Pattern: The radiation pattern of the antenna in use
Site Band: The frequency band of the selected cell
Electrical Down tilt: The electrical tilt in use, positive value refers to a down-tilt
ET Requires Site Visit: Unchecked by default. See Section 18.1.5, “Configuring Optimizable Parameters” for more details.
ET Requires Tower Climb: Grayed out by default. See Section 18.1.5, “Configuring Optimizable Parameters” for more details.
Azimuth: The azimuth of the selected cell
Mechanical Down-tilt: The mechanical tilt in use, positive value refers to a down-tilt
Height AGL: The antenna radiation center
ERP (CPICH Power): The effective radiated power (Pilot power for UMTS networks)
Forward Link Total Loss: Total loss on the forward link
Reverse Link Total Loss: Total loss on the reverse link
TMA: Check if TMA is used on the selected cell. Checking this box will result in canceling the reverse link total loss. Not applicable to ACP PRJs.
Parent Site: Site ID and the frequency band of the selected cells parent site
Alternative Site Name: Displays the alternative name (if any)
Alternative Sector Name: Displays the alternative sector name (if any)
Sharing Physical: Displays the cell ID of other cell(s) sharing the same antenna.
Antenna With: Typically this applies to dual band/tech cells sharing the same physical Dual-Band antenna.
Min MT + ET: Defaults to -20. See Section 18.1.5, “Configuring Optimizable Parameters” for more details.
Max MT + ET: Defaults to 20. See Section 18.1.5, “Configuring Optimizable Parameters” for more details.
Dual Band/Technology Cells
As discussed earlier, the ACP module supports multiple bands and technologies in one ACP PRJ. Figure 18.12, “Validating the Physical Parameters (Dual Band/Tech PRJ)” shows the ESD for a dual band/tech PRJ:
Figure 18.12. Validating the Physical Parameters (Dual Band/Tech PRJ)
In ACP, cells with dual band/tech are represented as two different cells with same lat/long, height, azimuth, and mechanical tilts. They may differ, however, with regards to the antenna model, antenna pattern, site band and electrical tilts. The band and technology information is also available in the “General Tab” of the ESD, and it is stored in the “PRJ_name.network.site.CSV” file in the PRJ folder.
Note
For the dual band/tech cells the following applies:
Antenna Model: Same antenna model on both cells (if using Dual-Band antenna)
Antenna Pattern: The pattern in use is for the selected cells frequency
Site Band: This should be the frequency in use for the selected cells technology
Electrical Tilt: This should be the correct value for the selected band
Sharing Physical Antenna With: Displays the cell ID of other cell(s) sharing the same physical antenna.
18.1.2. Network Data Validation
Display the cell level network parameters by selecting Edit > Sector (UMTS/GSM Tab) as shown in Figure 18.13, “Validating the Network Parameters”. Here, we will validate the following (example below is for a UMTS network):
Reverse Link:
Maximum Allowed Noise Rise: This is the maximum possible noise rise a cell is allowed to reach.
Noise Figure: Noise figure (NF) is a measure of how much a device (such an amplifier) degrades the signal to noise ratio for a given cell.
Noise Rise: Noise rise is the reverse link noise rise calculated by the simulator (or imported simulation results) for a given cell.
Forward Link:
Maximum PA Power: Maximum PA power of the selected cell. The calculated ERP is also displayed.
CPICH Power: The Common Pilot Channel power of the selected cell
SCH Power: The average Synchronization Channel power. Synchronization channels are active only 10% of the time-slot, therefore, their average power is calculated using: SCH = 10% of (Max Primary-SCH + Max Secondary-SCH).
PCCPCH Power: The average Primary Common Control Physical Channel power. The PCCPCH is time-multiplexed with SCH and is active 90% of the time-slot. It is calculated using:
PCCPCH
= 90% of Max PCCPCH
SCCPCH Power: The maximum Secondary Common Control Physical Channel power.
Power Allocated for All TCHs: Total power that can be allocated for traffic on the selected TCHs cell.
AS Threshold: The active set threshold relative to the strongest pilot.
Orthogonality Factor: Measure of isolation among different code channels from the same cell.
Percentage of Loading: The loading is calculated as the ratio of “Actual assigned DL traffic power” to the “Total allocated DL traffic power”.
Scrambling Code: The scrambling code assigned to the selected cell
Multipath Profile: Choose from the available (Flat, Pedestrian, vehicular) multipath propagation profiles
Soft Hand-off Loading: The maximum percentage of loading that can result due to primary users
Maximum Loading: The maximum allowed loading on the selected cell
Maximum Traffic Power: The maximum traffic power a RAB can have relative to Allocation Per User/RAB the CPICH power (absolute power in the case of a User)
Clutter Attributes Validation
Display the clutter attributes selecting Edit > Edit KPI Objective Settings > Clutter Settings, by selecting the Edit Clutter Attributes tool in the tool bar, or by double-clicking or right-clicking on the Clutter item in the Layer Manager side bar. Click on the appropriate technology tab. Validate the clutter specific weights and thresholds as shown in Figure 18.14, “Validating the Clutter Attributes” (example below is for a UMTS network):
Weight: These are relative weightings per clutter type. The optimizer gives priority to pixels based on the weights they carry. The optimizer uses this info to decide which pixel gets preference when doing the optimization, so pixels with a higher clutter weight have a better chance to get better coverage and quality. These are not “dB” values.
FL Threshold Ec: The forward link Ec threshold value (pilot coverage in dBm).
Max RSCP: The Maximum Best Server RSCP allowed for the clutter above which the pixel is penalized with ACP's Max RSCP Objective Cost Function. This is used to control the coverage in an Outside Network Border clutter from improving.
FL Threshold EcIo: The forward link Ec/Io threshold value (pilot quality in dB).
Penetration Loss - The penetration loss in dB for each clutter type.
Figure 18.14. Validating the Clutter Attributes
Note
Currently, these values are not imported from the planning solution PRJ (ASSET3G, PEV, Atoll) like other parameters. Therefore, new ACP PRJs have DEFAULT values. If licensed for the User Management module then default values can be defined by the user. See Section 21.5, “Manage Default Clutter Attributes” for details.
Important
Optimi recommends that the user very carefully consider the pixel counts for the various clutter types (right click on the displayed raster in Layer Manager, select Generate Histogram) in defining these weights. Optimi further recommends that the weights for pixel types whose covered counts are 25% or more of the overall covered pixel count for any one project be no less than half (50%) of the highest clutter weight.
Tip
The user may also import clutter attributes from another project. See Section 20.1.1, “Import/Export Clutter Attributes” for details.
Clutter Import Validation
It is very important that accurate pixel level clutter type information is available in the ACP PRJ (as explained in Section 17.3.6, “Import Clutter” earlier). To validate the clutter data import, click on the Layer Manager Display tree and select Raster > Physical > Clutter as shown in Figure 18.15, “Validating the Clutter Type Import”.
Figure 18.15. Validating the Clutter Type Import
Elevation Import Validation
It is very important that accurate pixel level terrain elevation (or heights) information is available in the ACP PRJ (as explained in Section 17.3.7, “Import Elevation” earlier). To validate the elevation data import, click on the Layer Manager Display tree and select Raster > Physical > Elevation as shown in Figure 18.16, “Validating the Elevation Import”.
Note
Edit > Edit KPI Objective Settings > Global Settings is used in conjunction with the “Site” option and the Auto Weight Adjustment option. See the section called “ACP Parameters (Optimization Categories and Settings)” for details regarding these features.
Note
Figure 18.16. Validating the Elevation Import
Pixel Profile
The user has the option of viewing the pixel profile by selecting the Pixel Profile button located in the tool bar. As seen in Figure 18.17, “ The Pixel Profile Tool” this functionality automatically docks in the right pane of the Main GIS view and shows the user information regarding the pixel profile between two points as selected in the Main GIS.
Figure 18.17. The Pixel Profile Tool
Note
Information presented includes:
Origin Lat and Lon
End Lat and Lon
Distance
Elevation Change
This information can be helpful in determining the reason behind certian RF propagation characteristics.
Traffic Demand Import Validation
It is very important that the desired traffic demand grid(s) are available in the ACP PRJ (as explained in Section 17.3.17, “Traffic Demand Grid” earlier). To validate the traffic demand import, click on the Layer Manager Display tree and select Raster > Physical > Traffic (Demand) and select the desired traffic map as shown in Figure 18.18, “Validating the Traffic Demand Import”. While the users can add multiple layers to the view, for validation purpose though, it is better to view one layer at a time. Verify all traffic demand maps, one at a time.
Figure 18.18. Validating the Traffic Demand Import
Note
Figure 18.19. Layer Manager
Using OLAP Tables for Data Validation
Imported PRJ data can also be viewed/validated using OLAP Tables. OLAP Tables are available by selecting View > OLAP Table. Selecting the parameters of your choice from this menu will provide information in the OLAP Table format. OLAP Tables are very flexible and powerful, the user
Note
The “Layer Manager Tree” can be used to change the Opacity of available layers as shown in Figure 18.19, “Layer Manager”.
can customize these as needed. These tables can be exported and saved in CSV, Excel, Word and HTML file formats. Figure 18.20, “Validating PRJ Data Using OLAP Tables” shows a Physical Sector Data OLAP Table.
Figure 18.20. Validating PRJ Data Using OLAP Tables
18.1.3. Using Groups in ACP
The groups in ACP are provided for organizing purposes. The users can create and assign different cells to different groups as needed.
While groups provide the ease of better managing a PRJ, they do not tell the optimizer what parameters to optimize. The idea is to use the groups while configuring the optimizer settings on a cell-level. Refer the example shown in the section called “Dual Band/Technology Cells”.
Groups Creation Tools
The user is provided with tools to create groups automatically if desired. These tools are:
Generate Tech/Band Groups - Accessed through Tools > Generate Tech/Band Sector Groups. This utility creates Tech/Band Sector groups based on the Tech/Band assigned to each sector. These groups provide ease of setting attributes by Tech/Band combination.
Generate Sector Status Groups - Accessed through Tools > Generate Sector Status Groups. This utility creates Sector Status groups based on the Sector Status assingned to each sector as seen in Edit > Sector > Physical tab.
Generate Co-Located Technology Groups - This tool is accessed by selecting Tools > Generate Co-Located Technology Groups. When this tool is invoked, the user is presented with a dialog wherein the attributes, technologies, and Group Class name of the group to be created can be entered. See Figure 18.21, “ Generate Co-Located Technology Groups Dialog”.
Figure 18.21. Generate Co-Located Technology Groups Dialog
Once created, the Group Class and Groups created can be used to easily select sectors and/or sites via the Edit > Sector dialog as seen in Figure 18.22, “ Edit > Sector - Apply Co-Located Technology Group Filter”.
This provides the user with an easy method of selecting sectors and/or sites that have multiple technologies for the setting of certain
attributes. As an example, once the groups are created, GSM sectors that are co-located with UMTS sectors can easily be selected and marked “Special Purpose” in the Edit-Site dialog so that GSM sites will not be removed in a GSM Site Selection optimization leaving only a UMTS site at that location.
Generate Tech/Carrier Sector Groups - Accessed through Tools > Generate Tech/Carrier Sector Groups. This utility creates Tech/Carrier Sector groups based on the Tech/Carrier assigned to each sector. These groups provide ease of setting attributes by Tech/Carrier combination.
Manual Groups Creation
The Groups tab of the ESD allows the user to define groups of cells in the PRJ. Groups can be created or deleted by using the Edit Groups window as shown in Figure 18.23, “Edit-Sector - Creating Groups”. The Edit Groups window can also be accessed via Edit > Groups.
Each group in ACP belongs to a group class. The user must create a group class before adding group(s) in it. Both, the class and group, must be created before assigning them to a cell. By default, all ACP PRJs have a group class called “REGIONS” that has five groups defined in it. These default groups cannot be deleted; however their use is optional.
Groups and Classes are defined as follows:
Class: A cell can be a member of more than one class.
Group: A cell can be a member of only one group within a class.
To create a new class, simply enter a name in the top Name input field and click on the New Class button. This creates a class type and will be shown in the List of Classes frame. To add a group to that class, select it from the List of Classes frame and enter a name of a group in the bottom Name input field and click on the New Group button. Repeat this to add more groups to the same class. To delete a group, open the Edit Groups window and simply select the class or group to be deleted, click on the Delete Class or Delete Group button.
Groups Assignment
Once the groups have been created, the group assignment can be performed by simply selecting a cell (or group of cells) and choosing the desired group from the desired class and clicking on the Apply button as shown in Figure 18.24, “Edit Sector - Assigning Groups”.
The following methods can be used to assign groups to different cells:
1. One cell at a time (using “Select”)
2. A geographical cluster of cells (using “Select Pixels in a Polygon”)
3. Cells with some common properties (using OLAP Tables)
Figure 18.24, “Edit Sector - Assigning Groups” above shows the usage of methods 1 & 2.
Method 3 involves selecting sectors using the OLAP view. In the example seen in Figure 18.25, “ Configuring By-Sector Contraints Using OLAP” the Physical Sector OLAP view has been used to filter and select all GSM1900 sectors with Antenna Family = 7770_00. Edit > Sector, ACP tab is then invoked to set the Electrical Tilt as desired. See Chapter 4, OLAP Table Overview for details regarding the manipulation of OLAP views.
Figure 18.25. Configuring By-Sector Contraints Using OLAP
Tip
In order to change ACP constraints for sectors with multiple antennas, the sectors selected must have the same number of antennas. Sectors with the same number of antennas can be selected via OLAP by applying a filter to the Number of Antennas field in OLAP and using the select buttons in OLAP to select these sectors. Setting up
constraints for different sectors can also be accomplished through the import of ACP Optimization settings. See the section called “Import/Export Optimization Constraints” for details regarding the Import/Export of ACP Optimization settings.
18.1.4. Save Project for Optimization
Before proceeding with the optimization, it is very important that we save a copy of the unoptimized (or Baseline) ACP configuration. The optimization process updates the existing predictions as well as all the optimizable parameter values in the configuration files, so it is essential to preserve the baseline configuration before optimization. The images of Figure 18.26, “Saving the Baseline Configuration” and Figure 18.27, “ Copying the Baseline Configuration” illustrate the recommended steps:
Figure 18.27. Copying the Baseline Configuration
Copy the Baseline configuration by right-clicking on the Baseline configuration in the Configuration Manager sidebar (or via File > Manage Configurations > Copy) and selecting “Copy” (sample directory shown in Figure 18.27, “ Copying the Baseline Configuration”).
Enter a name for the new configuration.
Select “Sector measurements / predictions, N-best Grids, and Traffic (Demand)” in the “Grid data to include” section of the Copy Configuration dialog.
Select “Set source configuration as baseline configuration.
18.1.5. Configuring Optimizable Parameters
The network parameters that can be optimized are available in the ACP tab of the Edit > Sector dialog as shown in Figure 18.28, “Edit Sector -
Optimizable Parameters”. In this dialog, the user can set optimizable parameters on a per cell basis. Each optimizable parameter has a button or drop down menu next to it.
Dual Band/Technology Cells
The optimizable parameters of dual band/tech cells must be configured for each band or technology individually. While the users may choose any method to configure dual band/tech cells, it is recommended to utilize “Groups” to accomplish this task. Once the groups are created and assigned to appropriate cells, it becomes very convenient to edit and apply settings on a per group basis. For example, Figure 18.29, “Configuring
Optimizable Parameters for Dual Band/Tech cells” shows a scenario where the GSM1900 cells are being configured to be optimized for the antenna type and electrical tilt. In this case, the following groups were defined:
Group Class = TECH_BANDS
Group Names (within the TECH_BANDS class) = GSM850 BAND, GSM1900 BAND, UMTS850 BAND Next, cells were associated to different groups depending upon their respective band/tech.
Finally, the optimizable parameters were configured for each group separately. Exact details on how to configure each parameter are presented in the remaining Section 18.1.5, “Configuring Optimizable Parameters” sub-sections.
Sector Status (Active/Inactive Sectors)
This feature allows the user to set certain sectors On Air or Off Air so that they will or will not be considered in optimization, reporting, and simulation functions. Additional choices include Candidate On Air and Candidate Off Air which are used in conjunction with the ACP “Site” option. See the section called “The “Site” Option (Site Selection)” for details on this feature. The Status setting is located in the Edit - Sector "Physical" tab "Status" drop down menu as seen in Figure 18.30, “Active/Inactive Status Drop Down”. The user is also provided with a Sector Status Physical GIS layer as seen in Figure 18.31, “ The Sector Status GIS View”. The n-best server grids are rebuilt automatically when one or more sector/sectors is changed from on-air to off-air or vice versa. As a part of this feature, in Tools - Options "RF Settings" tab (as seen in Figure 18.32, “RF Settings Tab”), the user can specify the use of Predictions, Drive Measurements, or Combined (Combined is available after smoothing or scaling) for all operations.
Figure 18.30. Active/Inactive Status Drop Down
Tip
Figure 18.31. The Sector Status GIS View
Antenna Type Optimization
A cell (or a group of cells) can be configured for antenna type optimization by clicking on the button next to the Antenna Model field in the “ACP” tab of the Edit > Sector window. The user will be presented with the Antenna Model Optimization Range dialog as shown in Figure 18.33, “Antenna Type Optimization - Set Range Window”.
Figure 18.33. Antenna Type Optimization - Set Range Window
In the above case, only two antenna types are available to the optimizer (as a valid option) when optimizing the antenna type for the selected cells.
The “Pole Shared Antenna” check box when checked tells the optimizer that the sector shares a pole, not just an antenna, with the same band different technology sector that it is antenna shared with. The antenna must be shared and the pattern match or it won't apply.
Electrical Down-tilt Optimization Note
The button next to the Antenna Model field can be used to manually change the current antenna assignment for the selected cell. Please remember, changing current antenna assignment will result in changing the current network configuration that would require updated RSSI information.
Tip
ALL available electrical tilts for both the existing antenna and any antenna selected in the Set Range dialog will automatically be selected and, as such, considered by the optimizer. The user can also choose to use “Select a Range of Items” in the Electrical Tilt Set Range dialog to limit the Electrical Tilts considered by the optimizer. It is NOT necessary to select the existing antenna in the Antenna Set Range dialog in order for the optimizer to consider all of the Electrical Tilts for the existing antenna.
A cell (or a group of cells) can be configured for electrical down-tilt optimization by clicking on the button next to the Electrical Downtilt field in the “ACP” tab of the Edit > Sector window. The user will be presented with the Electrical Tilt Optimization Range window as shown in Figure 18.34, “Electrical Down-tilt Optimization - Set Range Window”.
Figure 18.34. Electrical Down-tilt Optimization - Set Range Window
Note the following in the Figure 18.34, “Electrical Down-tilt Optimization - Set Range Window” above:
All selected cells are currently using the same antenna family (7770_00).
All selected cells are currenly using the 7770_00 antenna family in the Antenna 1 position.
All selected cells have the same # of antennas.
These cells are going to be optimized for electrical down-tilt and the available (or valid) option is to choose a tilt from 0 to 9 degrees from the (7770_00) family.
The user can opt to select a range of items that will be correlated to the appropriate patterns by the optimizer.
ET Requires Site Visit and ET Requires Tower Climb
Two check boxes are available in the Edit > Sector, ACP tab dialog so that the user can indicate the type of Electrical Tilt for the sector/sectors in question as seen in Figure 18.34, “Electrical Down-tilt Optimization - Set Range Window”. Some antenna's electrical tilt can be changed via remote control of a servo in the antennas (ET Requires Site Visit) where others are done manually on the antenna itself via a tower climb (ET Requires Tower Climb). “ET Requires Tower Climb” check box is grayed out by default until the “ET Requires Site Visit” is checked. Depending on the type of Electrical Tilt, the user will select one or both and the solution will add the dollar cost of the site visit and/or tower climb to the overall costs for the changes to the site in question if a site visit and /or tower climb was not already required for other changes.
Pole Shared Antenna
This check box allows the user to apply pole sharing to sectors that share the same physical antenna and pole. The sectors in question must share an antenna and the sectors must be using the same antenna pattern (Electrical Tilt). If not, it will fail, the box will be unchecked, and a message output to the log.
Tip
For multi antenna projects the user may set ET constraints by antenna model, regardless of the position of that antenna on the sector, by exporting optimization constraints and setting up the constraints as desired per antenna model. The file can then be imported back into xACP to set the constraints. Antenna model and antenna pattern are exported as a part of the optimization constraints file to aid the user. See the section called “Import/Export Optimization Constraints” for details regarding the import and export of optimization constraints.
Note
The antenna pattern (or antenna type) to antenna family mapping, which is required for electrical down-tilt optimization, is explained in Section 17.3.10, “Import Antenna Type and Electrical Tilt”.
Important
To optimize Electrical Tilt and not Antenna, it is not necessary to select the existing antenna for optimization. If the user desires to optimize Electrical Tilt and not Antenna, all sectors can be selected via the “Select All” button and “Optimize this variable” selected in the Set Range dialog for Electrical Tilt. All available electrical tilts for the existing
Azimuth Optimization
A cell (or a group of cells) can be configured for azimuth optimization by clicking on the button next to the Azimuth field in the “ACP” tab of the Edit > Sector window. The user will be presented with the Azimuth Optimization Range window as shown in Figure 18.35, “Azimuth Optimization - Range Window”.
Figure 18.35. Azimuth Optimization - Range Window
Range Settings
Relative - The valid optimization values are considered relative to the existing azimuth values.
Absolute - The valid optimization values are considered absolute (regardless of the existing azimuth values).
Minimum - The minimum setting to be considered.
Maximum - The maximum setting to be considered.
Increment - The increments to be considered.
Minimum Increment - The minimum increment to be considered.
Select Action
Edit Range Settings - Allows the user to edit the Range Settings (the default).
Convert to Absolute Range - Allows the user to convert Relative values to Absolute values (based on the current setting for the sector).
Convert to Relative Range - Allows the user to convert Absoute values to Relative values (based on the current setting for the sector). This button gives the user the option of converting the Range Type from Relative to Absolute for Azimuth, Mechanical Tilt, and PA/CPICH Power as seen in figure Figure 18.35, “Azimuth Optimization - Range Window”. The change is accomplished by taking the following steps:
Select Edit > Sector.
Select the sectors for which the range is to be changed.
Select the “Convert to Absolute Range” or “Convert to Relative Range” button. Range settings will be greyed out.
Figure 18.36. Change Range Type Example
Select “OK”.
Select “Apply” in the Edit > Sector dialog.
In the example in Figure 18.36, “ Change Range Type Example” the Azimuth for the selected sector is 30°. The Range was set for +/- 30°, relative. When the Range Type is changed to Absolute, the correct values for 30°, +/- 30° (Absolute) are automatically populated. The provides the user with an easy method to set absolute ranges for these attributes based on relative ranges so that the optimizer will be restricted to an absolute desired range when multiple optimizations are run.
Mechanical Down-tilt Optimization
A cell (or a group of cells) can be configured for mechanical down-tilt optimization by clicking on the button next to the Mechanical Tilt field in the ACP” tab of the Edit > Sector window. The user is presented with the Mechanical Tilt Optimization Range dialog as shown in
Figure 18.37, “Mechanical Down-tilt Optimization - Range Window”.
Range Settings
Relative - The valid optimization values are considered relative to the existing azimuth values.
Absolute - The valid optimization values are considered absolute (regardless of the existing azimuth values).
Minimum - The minimum setting to be considered.
Maximum - The maximum setting to be considered.
Increment - The increments to be considered.
Minimum Increment - The minimum increment to be considered.
Select Action
Edit Range Settings - Allows the user to edit the Range Settings (the default).
Convert to Absolute Range - Allows the user to convert Relative values to Absolute values (based on the current setting for the sector). See
the section called “Azimuth Optimization” for details.
Convert to Relative Range - Allows the user to convert Absoute values to Relative values (based on the current setting for the sector). See the
section called “Azimuth Optimization” for details.
Height AGL Optimization
A cell (or a group of cells) can be configured for antenna radiation center or height AGL optimization by clicking on the button next to the Height AGL field in the “Physical” tab of the Edit > Sector window. Doing this will bring the Set Range window as shown in Figure 18.38, “Height AGL Optimization - Range Window”.
Range Settings
Relative - The valid optimization values are considered relative to the existing azimuth values.
Absolute - The valid optimization values are considered absolute (regardless of the existing azimuth values).
Minimum - The minimum setting to be considered.
Maximum - The maximum setting to be considered.
Increment - The increments to be considered.
Minimum Increment - The minimum increment to be considered.
Select Action
Edit Range Settings - Allows the user to edit the Range Settings (the default).
Convert to Absolute Range - Allows the user to convert Relative values to Absolute values (based on the current setting for the sector). See
the section called “Azimuth Optimization” for details.
Convert to Relative Range - Allows the user to convert Absoute values to Relative values (based on the current setting for the sector). See the
section called “Azimuth Optimization” for details.
Height Options
Synchronize Heights - Checking this checkbox for one or more sectors of a site will result in the optimizer considering only height changes wherein all sectors for that site will be at the same height.
ERP (CPICH for UMTS networks) Optimization
A cell (or a group of cells) can be configured for ERP (CPICH for UMTS networks) optimization by clicking on the button next to the ERP (CPICH) field in the “Physical” tab of the Edit > Sector window. Doing this will bring the Set Range window as shown in Figure 18.39, “ERP (CPICH for UMTS Networks) Optimization - Range Window”.
Figure 18.39. ERP (CPICH for UMTS Networks) Optimization - Range Window
Important
If the Synchronize Heights option is selected for one or more sectors of a site whose sectors are not all at the same height, the selection will be rejected when the “Apply” button is selected and the option automatically turned off. Height tolerance is +/- one foot (.3048 meters).
Range Settings
Relative - The valid optimization values are considered relative to the existing azimuth values.
Absolute - The valid optimization values are considered absolute (regardless of the existing azimuth values).
Minimum - The minimum setting to be considered.
Maximum - The maximum setting to be considered.
Increment - The increments to be considered.
Minimum Increment - The minimum increment to be considered.
Select Action
Edit Range Settings - Allows the user to edit the Range Settings (the default).
Convert to Absolute Range - Allows the user to convert Relative values to Absolute values (based on the current setting for the sector). See
the section called “Azimuth Optimization” for details.
Convert to Relative Range - Allows the user to convert Absoute values to Relative values (based on the current setting for the sector). See the
section called “Azimuth Optimization” for details.
Maximum Radio Power (UMTS) Optimization
A cell (or a group of cells) in UMTS can be configured for Maximum Radio Power optimization by clicking on the button next to the Power Relative to CPICH field in the “UMTS” tab of the Edit > Sector window. Doing this will bring the Set Range window as shown in Figure 18.40, “Maximum Power Optimization - Range Window”.
Figure 18.40. Maximum Power Optimization - Range Window
Note
Range Settings
Relative - The valid optimization values are considered relative to the existing azimuth values - only relative range is enabled for Maximum Radio Power Optimization.
Minimum - The minimum setting to be considered.
Maximum - The maximum setting to be considered.
Increment - The increments to be considered.
Minimum Increment - The minimum increment to be considered.
Import/Export Optimization Constraints
Optimi xACP includes the ability for the user to import and/or export sector optimization settings. This functionality provides the user with an easy means of repeating optimization settings and/or sharing them with other users of the same project. As seen in Figure 18.41, “ Import Optimization Settings” the user is provided with the ability to import two separate constraint files:
ACP per Sector Flags, Settings, and Costs. The file is a .csv (comma separated values) file with the following fields:
sector_name antenna_number antenna_model antenna_pattern optimize_antenna_model dollar_cost_antenna_model_change optimize_antenna_height use_absolute_range_antenna_height min_range_antenna_height max_range_antenna_height increment_antenna_height min_increment_antenna_height dollar_cost_antenna_height_change optimize_antenna_azimuth Note
use_absolute_range_antenna_azimuth min_range_antenna_azimuth max_range_antenna_azimuth increment_antenna_azimuth min_increment_antenna_azimuth dollar_cost_antenna_azimuth_change optimize_antenna_mTilt use_absolute_range_antenna_mTilt min_range_antenna_mTilt max_range_antenna_mTilt increment_antenna_mTilt min_increment_antenna_mTilt dollar_cost_antenna_mTilt_change optimize_eTilt use_range_eTilt use_absolute_range_eTilt min_range_eTilt max_range_eTilt increment_eTilt min_increment_eTilt dollar_cost_eTilt_change optimize_power use_absolute_range_power min_range_power max_range_power increment_power min_increment_power dollar_cost_power_change min_et_plus_mt max_et_plus_mt min_pa_power max_pa_power
ACP per Sector Antenna Models. The file is a .csv (comma separated values) file with the following fields:
sector
antenna type
Figure 18.41. Import Optimization Settings
Note
For the Sector Antenna Models file each sector/antenna type combination is a distinct row.
Tip
For the latest format of the files, Optimi recommends exporting constraints from a project and modifying the exported file for import.
Optimizable Parameters Validation
After setting all the optimizable parameters, use the “Layer Manager Display Tree” to verify your settings as shown in Figure 18.42, “Display Tree - Optimizable Parameters Validation”.
18.1.6. Configuring the ACP Optimizer
After configuring the optimizable parameters on a per cell basis, we are now ready to set these parameters on a network wide basis. The various optimization parameters windows are available by selecting xACP > Optimization > ACP as shown in Figure 18.44, “Optimization Parameters - ACP Tab”.
ACP Optimization
In this dialog the xACP optimization parameters are configured as shown in Figure 18.44, “Optimization Parameters - ACP Tab”.
Figure 18.44. Optimization Parameters - ACP Tab
ACP Parameters (Optimization Categories and Settings)
The “Site” Option (Site Selection)
The “Site” checkbox provides the user with a means of having xACP add sites to the network as a part of each iteration before performing ACP optimization to optimize Coverage, Quality, and Capacity. The algorithm evaluates the coverage, quality, and capacity of the selected network or networks and adds sites considering the sectors marked “Candidate On-Air” (see the section called “Sector Status (Active/Inactive Sectors)”) as part of the candidate sites. Sectors marked “On Air” are considered to be part of the current network. The algorithm will automatically target the Service Levels populated for each band/technology combination in Edit > Edit KPI Objective Settings > Global Settings and add sites to the network until the target Service Levels are reached. See Figure 18.45, “ Edit Global Service Levels Dialog”.
Figure 18.45. Edit Global Service Levels Dialog
The algorithm will automatically add a number of sites for each iteration such that all sites will be added if the target Service Levels are reached.
The user is provided with an “Evaluate Network” option so that the current Network Service Levels can be understood in setting the Global Service Level settings. See the section called “Evaluate Network” for details regrading the Evaluate Network feature.
If, for example, the user wishes to run Concurrent ACP/Site Selection for the entire network, all UMTS sectors should be marked “Candidate On-Air”. If the Network Evaluation dialog shows 93% SL for Ec, 20% SL for Ec/Io, and 100% SL for FL EbNo and RL EbNo, the user would set the Global Service Levels as seen in Figure 18.45, “ Edit Global Service Levels Dialog”. The user can then select which physical attributes will be optimized as well as the “Site” option. When started, the optimizer will add sites for each iteration and performs ACP before adding more sites in the next iteration. xACP will continue in this manner until the Global Service Levels are reached. When the optimization completes, sectors belonging to sites added to the network will be marked “Candidate On Air” and sectors belonging to sites not added to the network will be marked “Candidate Off Air”. In the Group Class defined, the user will find an “Existing” group as well as the Selected and Not Selected groups defined.
When using the “Site” option, the optimizer also considers the “Cost of Adding Candidate Site” as set in Edit > Site > Costs tab. Sites that are cheaper to add to the network will be preferred according the to cost matrix in Figure 18.46, “ Financial Costs Matrix”. If the “Cost of Adding Candidate Site” is the same for all sites (defaults to $1) it will have no effect on the optimizer.
Figure 18.46. Financial Costs Matrix
Note
The RF parameters check-boxes in this dialog apply to the entire network. Cell-level settings are applied using the Edit > Sector (Physical Tab) window as explained in Section 18.1.5, “Configuring Optimizable Parameters”.
Tip
The Global Service Levels default to 100%. Since most networks do not have Service Levels of 100% for all KPIs, leaving the setting at default will usually result in the optimizer adding all sites marked “Candidate On Air” to the network.
Important
The number of sites added for each iteration is based on the number of iterations populated by the user according to the formula # Sites Added/Iteration = Number candidate sites / (Number of iterations - 2). If, for example, 5 iterations are selected, approximately 33% of the sites will be added for each iteration. Optimi recommends using a number of iterations such that approximately 10% of the candidate sites will be added for each iteration.
Benchmarking performed by Optimi shows that this will provide the best results while keeping optimization time to a minimum. Optimi also recommends using the Auto Weight Adjustment (checked by default) feature when using the Concurrent ACP/Site Selection feature. This option causes ACP to target the Global Service Levels so that both the ACP and Site Selection portion of the algorithm will be tagetting the same Service Levels.
Note
If the Capacity Layer option is selected and the Concurrent ACP/Site Selection is run, the optimizer will consider the capacity layer algorithm in adding sites to the network. This means that capacity layer site will automatically be preferred and thus added first to the network.
Tilt Settings
The Tilt Settings button allows the user to specify settings that will restrict uptilt and/or force downtilt for sectors based on Overshooting Rank (see Section 23.4, “OSS Based ACP Reports” for details regarding the Boomer Status Report and Overshooting Rank). Also the automatic downtilt can be forced based on DCR stats, loaded from OSS.
Figure 18.47. ACP Tilt Settings Dialog
As seen in the user has the following options:
Downtilt Boomers - Enables the automatic tilting and no uptilt for boomers feature.
Threshold 1 - No uptilt (ET + MT) will be allowed by xACP for sectors whose Overshooting Rank (as viewed in the Boomer Status Report) is higher than this value.
Threshold 2 - .xACP will force 2 degrees of tilt (ET + MT) on sectors whose Overshooting Rank (as viewed in the Boomer Status Report) is higher than this value AND whose Bad Coverage Threshold is below the translated value.
Bad Cov. Threshold - Bad Coverage Threshold (as seen in View > OLAP Table > Network > UMTS > OSS Data) used in conjunction with Threshold 1 which sectors must be below for the forced 2 degrees of downtilt to be applied.
Azimuth Settings
The Azimuth Settings button allows the user to specify the minimum angle of separation between sectors of the same site. See .
Figure 18.48. The ACP Azimuth Parameters Dialog
Tip
Capacity can be set by sector in Edit > Sector > General tab Max Erlangs or in Edit > Site, Capacity tab. The optimizer will use whichever capacity limit it “bumps” into first. If the “Capacity at Tech/Band” option is checked in Edit > Site, Capacity tab, xACP will apply the max erlang value entered by the user to each Tech/Band associated with each site. If a single site has, for example, two GSM band, checking the “Capacity at Tech/Band” option effectively doubles the capacity for this site at the site level.
Important
The Cost of Adding a Candidate site can be set in Edit > Site, Costs tab.
Important
The Boomer Status Report must be invoked for the ACP Tilt Settings feature to work properly. If no Boomer Status Report is available, the feature will have no effect on the optimization outcome.
Note
Forced downtilt changes for sectors whose Overshooting Rank (as viewed in the Boomer Status Report) is greater than Threshold 2 will be forced to the top of the scheduled changes.
Important
The Minimum Angle of Separation setting takes into account the beamwidth of the antenna. This means that the angle translated will be the minimum angle between the two closest 3 dB points of adjacent sectors. For example, if a three sectored site has 80° beamwidth antennas (240° total) and the sectors are oriented equally around the site, a setting of 40° or more will prevent the Azimuths from changing other than a change that will move all three
Height Settings
The Height Settings button allows the user to specify whether or not the optimizer should synchronize height settings. See Figure 18.49, “ The ACP Heights Parameters Dialog”.
Figure 18.49. The ACP Heights Parameters Dialog
Site Settings
The Site Settings button allows the user to specify the maximum number of sites to add when using the “Site” (Concurrent ACP/Site Selection) option as seen in Figure 18.50, “ Max # Added Sites Dialog”.
Figure 18.50. Max # Added Sites Dialog
Checking the box and specifying a maximum number of sites to add will result in the optimizer ceasing to add sites to the network once that number of sites is reached regardless of the Service Level.
$ Cost per change
This is the $ cost associated with each RF parameter change. The available $ amount is limited by the total $ Budget value. The overall objective function of the optimizer is a combination of RF and budget costs.
$ Budget
This is the total available $ budget allocated for the optimization session. A lower $ budget may result in limiting the total number of possible changes.
# Changes/Milestone
This is for administration purposes only. This value does not limit the number of changes the optimizer can make. It simply divides the total number of changes by the value entered in the #Changes/Milestone field such that each milestone (group of changes) results in a net improvement to system performance. For this reason, Optimi recommends that recommended changes be implemented in complete milestones only.
For example, using a value of 30 in the #Changes/Milestone field means that the “AcpChangesScheduleAggregate” report will get a maximum of 30 changes per milestone. If in the example of 30 Changes/Milestone, the optimizer comes up with a total of 100 changes, now the report should have the following:
Milestone1 = 30 changes
Milestone2 = 30 changes
Milestone3 = 30 changes
Milestone4 = 10 changes
Run Schedule Changes
This check-box should be selected if the user desires that the Aggregate Schedule file be created. The schedule generator groups the changes into those that require a site visit (Azimuth, MT) and those that do not require a site visit (ET, Power). It then finds the changes that provide the most positive effect on the system and do not require a site visit and schedules those changes first, grouped by site. It then moves on to changes that do require a site visit. In SLOW mode, this process is undertaken again to find the next best changes (once the first set are applied). This continues until all changes are considered. In FAST mode, the first order of changes is taken. For this reason, SLOW mode provides a more accurate schedule but can take many hours in a large project. SLOW mode is recommended
sectors the same amount in the same direction. This also means that a setting of zero will prevent sector overlap within the 3 dB points of the antenna pattern.
Note
The “Synchronize Heights” option must be turned on at the sector level for this setting to have any effect. See the section called “Height AGL Optimization” for details.
Note
The budget cost may be overwritten by entering large $ budget limit and small individual budget items (i.e., $cost/change)
Tip
If the user desires to run more than one optimization to experiment with different settings, it is recommended that Run Schedule of Changes NOT be selected until the final run. This will save time.
Technology and Band
Select the appropriate PRJ technologies and bands. The ACP module allows the users to include sites of multiple technologies and bands in one ACP PRJ. However, as detailed in Section 17.3.8, “RF Data”, PLOSS data relevant to each technology and band must be present for each cell.
Technology/Band Traffic Grid
Here, the user can select the desired traffic demand grid from the drop-down list to be used while optimizing the network. For UMTS
band/technology combinations the traffid demand grid is associated with the UMTS Simulation Profiles configured in Edit > UMTS > Simulation Profiles.
Use Capacity Algorithm (GSM)
This check-box allows the user to optimize both layers (bands) of a dual-band GSM network concurrently. When selected, the “other” band will be grayed out. The user must set the capacity and coverage layer bands via the drop down dialogs. The solution will load data from both bands. Where the best-server RSSI for the capacity layer band is >= the Capacity Layer Coverage Threshold setting for the capacity layer band (settable in Edit-Clutter Attributes), that capacity layer band will be assigned all of the traffic from that bin and the capacity layer band will be optimized. The coverage layer or “other” band will be ignored. Where the best-server RSSI for the capacity layer band is NOT met, the coverage, or “other” band will be optimized. This allows for optimization considering dual-band networks layered using Hierarchical Cell Structures. The user can exclude high frequency band sectors from the capacity layer rules by specifically assigning them to the coverage layer. This can be done from the Edit > Sector... window by clicking on the Coverage Sector option for the sectors of interest.
Sector Group Settings
The Sector Group Settings portion of the dialog provides the user with a means of defining the group class and group names for sites that are kept and sites that are removed as a result running a Concurrent ACP/SS optimization (see the section called “The “Site” Option (Site Selection)”). Sectors whose status is“On-Air” before optimization will be placed in a group name named “Existing” in the defined group class.
Evaluate Network
Selecting this button results in the xACP solution calculating the Coverage, Quality, Capacity and Dominance Service Levels for the band/technology combinations checked. The user is provided with a tab showing the Service Levels for each band/technology combination as well as an “All” tab as seen in Figure 18.51, “ The Network Evaluation Dialog”.
Figure 18.51. The Network Evaluation Dialog
The Service Levels presented are calculated using the Data Source as set in Tools > Options, RF Settings tab and include all sectors marked On Air or Candidate On-Air. If the user wishes to evaluate the network without Candidate On Air sectors, these sectors must be marked “Off Air” before invoking Evaluate Network The user can also initialize the optimizer by selecting “OK” (“Run Optimizer in Batch Mode” UNchecked) and note the values under “Initial” on the left side of the ACP Optimization Status dialog. See the section called “Sector Status (Active/Inactive Sectors)” for more details regarding sector Status.
The Objective Tab
Here the user can enter the technology specific optimization weights with relative importance given to coverage, capacity and quality. The set of weights displayed in the objective tab depends upon the number of technologies checked in the ACP tab. Each set of weight applies only to the labeled technology. Additionally, this window facilitates the inclusion of population, clutter and traffic data for optimization consideration as shown in Figure 18.52, “Optimization Parameters - Objective Tab”.
Figure 18.52. Optimization Parameters - Objective Tab
Note
Only band/tech combinations for which there are prediction, measured, and/or combined RSSI grids in the project will be available in the GUI for optimization.
Note
For multiple band or technology PRJs, the optimizer will search for the best combination of changes given that they impact both technologies/bands.
Optimization Weights
These technology specific weights are relative values (unit less). A value of 100 for all is the same as a value of 10 for all. What is important is the relative difference between these weights.
For a new network, with no or minimum knowledge of the network performance, the user may start the optimization using equal weights for capacity, coverage and quality. After the initial optimization run, the user can refer the optimization results to get a much better feeling about the current performance of the network. At that point, the weights can be tuned as needed. For more details, refer to Section 19.5, “The Reports Tool”.
Large Cell Prevention - Traffic Growth %
The Large Cell Prevention - Traffic Growth % value provides the user with a method of preventing the optimization results from including very large service area sectors. When the optimizer is run on UMTS systems that have very low traffic, the resulting design can result in some sectors with a very large service area. This can occur because the optimizer is concerned only with coverage and quality (including traffic quality) taking into consideration the traffic demand grid set for optimization by the user. As traffic grows, sectors with a very large service area can become problematic. By populating a value in the provided box the user can quickly and easily limit the downlink loading for each sector based on its current Max Loading. This has the effect of evenly spreading the loading amongst the sectors and preventing large cell service areas. This is accomplished by setting the Max Loading for each sector according to the formula: Max Loading = Max Loading/(1 + growth/100). For example, if Max Loading is set to 50% for all sectors, setting a value of 100% for Traffic Growth will result in a Max Loading of 25% for all sectors. Using this feature the user can optimize a UMTS network while considering a unitform growth factor.
Calibration Options
“Iterations to calibrate” - This field is applicable for UMTS ACP and LTE ACP, it provides the user with a method of having the Optimi X solution calibrate the optimizer loading between iterations. When translated to a value > 0, the optimizer will run a simulation every “x” iterations in order to re-calibrate Forward Link Loading and uplink Noise Rise that has an impact in UMTS/LTE network quality and coverage for both uplink and downlink. This option can make the final-optimized system's coverage, quality, and capacity better. Benchmarking performed by Optimi indicates that the resulting improvement is typically very small and thus may not be worth the addition time it takes to run the simulator every “x” iterations.
x Population
Checking on the “x Population” check box allows the optimizer to prioritize pixels based on the population data imported using the Import > Traffic > Population Count. Pixels with a high population count will get priority in terms of receiving better coverage, capacity and quality.
x Clutter
Checking on the “x Clutter” check box allows the optimizer to prioritize pixels in different clutter types based on the Clutter weightings (as set in Edit > Edit KPI Objective Settings > Per Clutter Settings).
x Traffic
Checking on the “x Traffic” check box allows the optimizer to prioritize pixels based on the selected traffic distribution(s). The optimizer allows the user to optimize the network simultaneously for multiple traffic types that represent the different services offered to the network subscribers. For example, different services could be defined for voice users and Internet users, or for indoor users and outdoor users. This traffic distribution is:
NOT used to calculate the interference resulting due to the network users (traffic).
Used ONLY to weight pixels (differentiate between pixels) in terms of the traffic these pixels carry. Note
The clutter specific thresholds (such as Ec, Ec/Io, Eb/No, etc. for UMTS PRJs) are always considered regardless of the “x Clutter” check-box being checked or unchecked.
The optimizer uses this information to decide which pixel gets preference when doing the optimization, so pixels with relatively more traffic have a better chance to get better coverage and quality.
Dominance - Number of Servers and C/I Threshold
The Dominance section provides the user with a method of setting dominance criteria. The user is provided with fields to populate a Number of Servers and a Dominance threshold. The optimizer will consider bins that have less than the translated number of servers within the translated signal threshold of the best server to be covered from a dominance perspective. For example, if the user populates 8 servers and a threshold of 12 dB, any bin which has 7 or less servers within 12 dB of the best server will be considered to be covered from a dominance perspective. Using this option will prevent the optimizer from making changes that would result in the loss of a dominant server for the area in question and thus introducing a potential interference problem.
Use Neighbor Penalty
The Use Neighbor Penalty checkbox provides the user with a means of using the dominance settings to enforce a penalty when one or more of the “x” servers within “y” dB is not a neighbor. When the Use Neighbor Penalty checkbox is checked, xACP will generate the user-defined number of direct neighbors for each sector and use the dominance settings to apply a penalty for each bin where one or more of the “x” servers within “y” dB of the best server is not a neighbor. This feature has the effect of preventing large uptilts that can be problematic as system traffic grows.
UMTS Multi Carriers Options
UMTS Multi Carriers Options provides the user with a method of setting the coverage criteria for multi carrier UMTS optimization:
At least one carrier has coverage - The optimizer will consider the bin covered if at least one carrier meets the coverage criteria.
All carriers have coverge - The optimizer will consider the bin covered only if all carriers meet the coverage criteria.
Active Set Size
This value is the target Active Set Size for UMTS. The optimizer will seek to keep the Active Set Size at or below the translated value.
HSDPA CIR Target
This value is the target CIR for HSDPA enabled services. The optimizer will seek to keep the the CIR for HSDPA enabled services at or above the translated value.
LTE Options
The max IoT value is the maximum allowed level of Interference-over-Thermal (IoT) per sector before ACP starts penalizing due to excessive uplink interference. This IoT term penality prevents the uplink capacity from growing when increasing the coverage area if there is a degradation in the uplink quality. The IoT penalty is included as part of the uplink capacity penalty contribution combined together with the sector overload.
The Optimizer Tab
Clicking on the Optimizer Tab will display the window as shown in Figure 18.53, “Optimization Parameters - Optimizer Tab”.
Figure 18.53. Optimization Parameters - Optimizer Tab
Tip
Dominance Weight must be > 0 for the Use Neighbor Penalty feature to function correctly.
Warning
Like any setting that constrains the xACP optimizer, benchmarking performed by Optimi shows that the “Use Neighbor Penalty” option can result in sub-optimal results. While limiting large uptilts can be good for future system growth they are sometimes required for optimal system performance in the present. Optimi recommends that the user verify the project is complete by using the ACP Consistency Check (see the section called “ACP Consistency Check”) and add any expected growth to loading and/or demand grid values to be used for optimization.
