Definition of Traffic for Network Planning Projects

Transcription

1 Definition of Traffic for Network Planning Projects AWE Communications GmbH Otto-Lilienthal-Straße 36 D Böblingen Issue Date Changes V0.1 Oct First version of document V1.0 Aug Second version of document after pre-release of V13

2 1. Introduction Wireless mobile networks are designed to provide high quality services to as many users as possible. Normally a tradeoff between quality of service and maximum number of users that can be served has to done. Therefore the number of users and the traffic they cause within a wireless communication network is a crucial parameter for network design and optimization. In order to consider different traffic loads during planning and optimization of wireless communications networks, WinProp offers the possibility to define location dependant traffic definitions for radio network planning projects in rural, urban and indoor environments. The following chapters highlight an approach to define location dependant traffic assumptions in WinProp. 2/13

3 2. Creation of Clutter Maps 2.1. Rural Scenarios Rural or suburban environments are usually modeled using digital terrain elevation databases. Optionally clutter databases (c.f. Figure 1) can be used additionally in order to increase the prediction accuracy. These land usage databases of rural simulation projects can be used directly in order to define traffic assumptions in ProMan. Figure 1: Land Usage Classes of an Island 2.2. Urban and Indoor Scenarios In contrast to rural environments, urban and indoor scenarios are usually modeled quite detailed based on 3D vector databases. In order to specify different regions for location dependent traffic assumptions, clutter maps have to be created additionally. This can be done with the WallMan application. First of all floor planes have to be defined. Floor planes represent building floors in case of indoor databases or the ground plane for urban databases, respectively. Therefore an arbitrary number of floor planes can be specified for an indoor database, whereas for urban databases only one ground plane is possible. Floors can be defined, edited or deleted with the floor definition dialog, which can be reached via Edit menu ('Edit -> Floors...') or the corresponding toolbar icon. 3/13

4 Figure 2: Floor Definition Dialog The button on the lower left side of the dialog depicted in Figure 2 offers the possibility to add or modify clutter classes manually. Figure 3: Definition of Clutter Classes Clutter classes which are defined here can be assigned to the clutter maps of the defined floor levels either automatically during creation of the clutter maps (see chapter and chapter 2.2.2) or graphically using mouse tools (see chapter 3). For urban databases, the manual definition of clutter classes is not mandatory, as they can be created also automatically as described chapter /13

5 2.2.1 Creation of Clutter Maps for Indoor Databases After one or multiple floor levels have been defined for the indoor database, a clutter map can be created for each of the floors using the properties dialog of a floor which is depicted in Figure 4. This makes it possible to define an individual clutter map for each building floor. Figure 4: Floor Properties Dialog A clutter map will be created or deleted if the option 'Create clutter map for this floor' is selected or unselected, respectively. Location, extension and resolution parameters of this map are initialized according to the current maximum database extension. However, these values can be changed using the corresponding edit fields in the lower part of the Clutter Map section. In case clutter classes have been defined earlier (c.f. chapter 2.2), the created map can be initialized with one of the defined clutter classes which can be selected in the drop-down box on the right side. If the option 'Initialize with selected clutter class considering building(s)' is selected, the initialization will be done only within the bounding of the building(s) whereas the outdoor areas remain undefined. In case arbitrary prediction planes are defined within an indoor database it is possible to assign a specified clutter class to these planes. This can be done for the selected prediction plane object either via the Object Properties dialog (c.f. Figure 5) or the corresponding context menu item. 5/13

6 Figure 5: Object Properties Dialog Creation of Clutter Map for Urban Databases For urban scenarios only one clutter map can be defined per database. After a ground plane has been defined, a clutter map can be created using the properties dialog of the floor which is depicted in Figure 6. Figure 6: Floor Properties Dialog The clutter map will be created or deleted if the option 'Create clutter map for this floor' is selected or unselected, respectively. Location, extension and resolution parameters of this map are initialized according to the current maximum database ex- 6/13

7 tension. However, these values can be changed using the corresponding edit fields in the lower part of the Clutter Map section. In case clutter classes have been defined earlier (c.f. chapter 2.2), the created map can be initialized with one of the defined clutter classes which can be selected in the drop-down box on the right side. If the option 'Initialize with selected clutter class considering building(s)' is selected, the initialization will be done only within the bounding of the buildings whereas the outdoor areas remain undefined. Clutter classes can be created also automatically by using the fourth option ('Initialize with clutter class depending on building height') to initialize the clutter map. In this case a clutter class will be created for each building height, taking into account the specified floor height (see Figure 7). This option makes it possible to easily create a clutter map based on building heights which can be used directly for traffic definition, for example according to the principle "the higher the building the higher the expected traffic", in ProMan later. Figure 7: Automatically Generated Clutter Classes for an Urban Database 7/13

8 3. Edit Clutter Maps Clutter maps can be modified graphically using the mouse tool 'Edit Clutter Database', which can be selected in the Edit menu ('Edit -> Clutter Database...') or via the corresponding toolbar icon. After selecting the tool, a dialog opens where the modification to be done can be specified in detail (see Figure 8). Figure 8: Edit Clutter Map Using the drop-down box in the section Clutter Class, the clutter class to be assign can be selected. In the center of the dialog the drawing mode, i.e. the clutter classes and floor planes to be considered, can be specified. Figure 9: Selection of Classes to be considered If a clutter class is chosen to be not considered for a drawing operation, it will not be overwritten with the selected new clutter class. This makes it possible to draw seamless. Beyond this, the user can select which floor plane shall be affected by the drawing operation using the second drop-down box within the Mode section. Therefore it is very easy to change the clutter maps of multiple building floors simultaneously with a single operation. In the lower part of the dialog, the paint tool to be used can be specified. The data can be changed either using a rectangular, a polygonal or a line shaped draw tool. 8/13

9 4. Definition of Traffic in ProMan After the specification of the clutter maps in WallMan, a regular network planning project can be set up in ProMan. The definition of traffic setting can be done in the project settings. These settings can be reached via Project > Edit Parameter. In the tab sheet Traffic the definition of all relevant parameters is possible. There are two different methods for the definition of traffic. Both approaches are explained in the following sections Traffic independent of location If the traffic is defined independent of the location a traffic map is not required because it is assumed that the traffic is homogeneously distributed over the complete prediction area. But for each transmitter individual assumptions can be made. Figure 10: Traffic definition for location independent method The settings for the transmitters are the following: Assumed mean cell load (in %) Assumed mean noise rise (in db) Power backoff for cell assignment channel (in db) 9/13

10 These values can be defined for all transmitters equally or individually for each transmitter on the traffic page. Figure 10 shows the definition of individual properties for each transmitter in the location independent traffic mode. The default values for cell load, noise rise and power backoff can be defined in the upper section of the property page. In the lower part all transmitters of the current project are listed and the settings for each transmitter are displayed in the table. The text default indicates that a default values defined in the upper section of the page is used for the corresponding transmitter. If individual settings for a transmitter shall be defined the transmitter has to be selected in the table and the check- and editboxes at the bottom of the page can be used to define individual values for cell load, noise rise and power backoff Traffic dependent of location For the definition of location dependent traffic a traffic map is necessary. The generation of traffic maps is explained in Section 2. Figure 11 shows the property page for location dependent traffic with several applications. Figure 11: Traffic definition for location independent method Location dependent traffic requires the specification of at least one application. Reasonable applications are e.g. Voice Calls, Video Calls and WWW Downloads. Applica- 10/13

11 tions can be added, edited and removed in the upper left part of the traffic property page. Figure 12: Parameters for a new application. For each application the following values must be specified (see Figure 12): Name: Description of application. Position: Priority of the application. 0 means highest priority. Activity (in %): Activity of users using this application. Traffic mode: Either arrival rate in 1/sec/m² and hold time in sec or traffic in Erl/m² can be defined. At least one transmission mode must be assigned to each application. If an application is selected with the mouse, the assigned transmission modes are displayed in the upper right part of the property page. If another application is selected by the user, the display of the transmission modes is refreshed automatically. In the example of Figure 11 two transmission modes are defined for the application Voice Calls. Transmission modes can be added or removed with the corresponding buttons. The parameter Position specifies again the priority (0 means highest priority). In the lower left part of the property page the clutter classes assigned to the selected application are displayed. If another application is selected by the user, the display of the clutter classes is refreshed automatically. Clutter classes can be added or removed with the buttons in the lower left section. When a clutter class is selected with the mouse the traffic values are displayed in the lower right area. The user can now modify the values and thus assign them to the selected clutter class. Depending on the traffic mode specified for the current application (see above) either two values (arrival rate in 1/sec/m² and hold time in sec) or one value (traffic in Erl/m²) must be defined. The unit for the area definition (either m² or km²) can be modified with the drop down box at the top of the page. 11/13

12 5. Outputs of Monte Carlo Simulations in ProMan For the radio network planning in ProMan considering location dependent traffic based on Monte Carlo simulation the additional reports for the traffic analysis can be generated, as shown in the following dialogue. Figure 13: Parameters for the traffic simulation reports Traffic simulation report The traffic simulation report in ProMan (see the next figure) based on the Monte Carlo approach evaluates the numbers of served, blocked and not assigned mobiles (users) for each application and for each cell. Furthermore the results are given for the total simulation area (considering all cells) and for the sum of all defined applications. There are 4 different states for a mobile generated in the Monte Carlo simulation as shown in the following table: State served Description The mobile is served by the cell and the corresponding radio resources are allocated for the defined application. Not assigned Cell assignment not feasible for the corresponding location (signal level too low and/or SNIR too low), i.e. white pixels in cell area map. Blocked (traffic) => Coverage holes need to be filled by additional base stations. Cell assignment possible for the corresponding location and Rx power as well as SNIR sufficient for the desired transmission mode. But the required radio resources are not available in the corresponding cell (codes in CDMA, time slots in TDMA,...). => Addition of further carriers required or smaller cell for the hot spot areas. 12/13

13 Blocked (quality) Cell assignment possible for the corresponding location, but for the desired transmission mode the Rx power and/or the SNIR is not sufficient (interference too high). => Interference reduction required (modification of Tx power, antenna pattern or carrier assignment). Figure 14: Example of traffic simulation report. 13/13