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EDX Software

Reference ManualNetwork Design

Module:

WiMAX Systems


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EDX Wireless NDM: WiMAX Systems ReferenceManual Table of Contents

i

Reference ManualNetwork Design Module:

WiMAX SystemsTable of Contents

1. WiMAX Systems ................................................................ NDM-WM-11.1. What is the WiMAX Section of the Network Design Module? ........................... NDM-WM-21.2. Installing the Network Design: WiMAX Systems Module ................................... NDM-WM-21.3. Starting a WiMAX System Design ............................................................................ NDM-WM-21.4. Accessing the Network Design Module: WiMAX Systems Functions ............... NDM-WM-21.5. System Details / Service Area .................................................................................... NDM-WM-31.6. Preamble Code Planning ............................................................................................. NDM-WM-61.7. Neighbor Lists .............................................................................................................. NDM-WM-71.8. Frequency Planning ..................................................................................................... NDM-WM-9

1.8.1. Frequency Planning Parameters ............................................................................................NDM-WM-101.8.2. Automatic Frequency Planning (AFP) ...................................................................................NDM-WM-9

1.9. Traffic Planning for WiMAX Systems .................................................................... NDM-WM-151.9.1. Traffic Data Source ................................................................................................................NDM-WM-151.9.2. Packet Switched Traffic Definitions and Densities ...........................................................NDM-WM-15

1.10. WiMAX Studies .......................................................................................................... NDM-WM-171.11.WiMAX Study System Reports ............................................................................... NDM-WM-21


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EDX Wireless NDM: WiMAX Systems Reference Manual

1996-2012, EDX Wireless - All rights reserved. Revised: 2012/08/01

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1.WiMAX Systems

1.1.What is the WiMAX Section of the NetworkDesign Module?

The Network Design Moduleis an optional EDX softwaremodule connected to EDXSignalPro. The WiMAX SystemsSection of the Network Design Module (NDM-WMX)gives you the advanced, specialized system engineering capabilities needed to design,re-configure, and optimize fixed and mobile WiMAX networks.

TheNDM-WMcontains special data entry dialog boxes in which you can specify theparticular fixed or mobile WiMAX or WiBRO system profile in use, frame duration,and other details pertaining to that system as well as allowing access to special areastudies for those system types.

In performing its tasks, this module makes use of many basic signal level calculationtechniques that are accessed through EDX SignalPro. A cell site sector (whetheromni-directional or sectorized), is analogous to a transmitter site in EDX SignalPro.When you run a WiMAX study map, the program will extract terrain and land use(clutter) data, calculate signal levels, and build a composite area study grid in thesame way it does in the main program for a transmitter site (see Section 8.5for themain Reference Manual). It will create .rad files for each cell sector just as it did foreach transmitter site. It is helpful to reviewSection 8.5for more background on thisprocess.

This module also relies on the database settings that are made in the main EDXSignalPro program. Setting up terrain, land use (clutter), traffic, and demographic

databases that are used by the NDM-WMXis done on the Databases menu fromthe Main Map menu.

You can also use the extensive mapping and drawing capabilities in EDX SignalProto create very detailed and informative base maps for your WiMAX system studies.Detailed base maps are an important tool for determining where cell sites may belocated, judging where system capacity may be insufficient (or under-utilized), andgauging how your system needs to evolve to accommodate changing traffic patterns.Drawing maps of traffic (data rate or call density) is a fundamental part of whatEDX SignalProsmapping capabilities can do (see Chapter 7in the Reference Manual).

Because theNDM-WMXoffers specialized add-on capabilities, it is important to be

fluent with the basic operation and functions ofEDX SignalPro before attempting touse this module.

1.2. Installing the Network Design: WiMAXSystems Module

The capabilities of this module are automatically installed when you install EDXSignalPro (with theNetwork Design Module: WiMAX Systems) as described in Chapter 1


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EDX Wireless NDM: WiMAX Systems


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of the Reference Manual. There is no separate installation to be done. The modulecode is built into the program and the hardware key you receive contains the properauthorization codes to activate theNetwork Design Module: WiMAX Systems. To verifythat the module is properly installed, select Help/About on theEDX SignalPro mainmenu. It will indicate whether or not the module is installed.

1.3. Starting a WiMAX System Design

The standardEDX SignalPro program stores information for a study in the projectdirectory. This directory contains all the parameters and other information needed tocompletely reproduce a study map on your screen when you open a selected project.The project includes the specific parameters for each of your transmittersites/sectors, or links, as well as information about the databases, propagationmodels, and base map features. Projects are explained in Chapter 3 of the ReferenceManual.

The material in this NDM-WMX manual is presented assuming you have alreadyread the Users Guideand the Reference Manualthat are included with your software. If

you have not done so, please review these materials before moving on to thefunctions described in the following chapters.

1.4.Accessing the Network Design Module:WiMAX Systems Functions

If you have started a new project, or opened an existing one, the Network DesignModule: WiMAX Systemsfunctions will be available to you. To accessNetwork DesignModule: WiMAX Systems, select the Network Design/Analysis item on the main

EDX SignalPro menu, then select WiMAX systems. A Sub-menu will appearshowing the various elements provided by the module for this system type. Therewill also be an additional category of studies available when a new area study isadded to a project.


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1.5. System Details / Service Area

This dialog allows the configuration of the WiMAX or WiBRO system profile andparameter appropriate for the system being designed, as well as the assignment of achannel plan template file, service area boundary file, and measure sectorinterference file (if this feature is being used in lieu of calculated interference).

When a particular system profile is chosen from the drop-down list, the FFT size,channel bandwidth, and TDD or FDD selection will be chosen automatically unlessyou choose a Custom profile in which case you will need to specify these values.You may then also specify the frame duration, cyclic prefix, uplink/downlink ratio,and the percentage of each frame allocated to a specific permutation type (eg, PUSC,FUSC). These parameters are used in addition to the details from the adaptivemodulation dialog to find the results for the various traffic or data rate studies whentheyre run.


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The handoff section allows you to specify whether the system will determinehandoff based on a specific power ratio between the servers in question at theremote or on the absolute received power level of the current server. Once thecorrect option has been chosen, you can enter the values that will be used for thehandoff study.

There is also an option to model power control in WiMAX studies. Some WiMAXstandards provide for reduced transmit power to be used for sessions with good linkquality. Checking this box will add power control algorithms to the WiMAX uplinkStochastics study.

The channel plan template file must be specified in this dialog in order to assignchannels to any sector specified as a WiMAX system type. This file describes thearrangement of channels within the system including center frequency, bandwidth,and so on. The WiMAX systems module makes use of the EDX version 3 channelplan template file, the description for which may be found in the Reference ManualforNetwork Design Module: Multipoint Systemsof this manual, section 3.2.1.

When selecting a channel plan template for a WiMAX project, there is an option tomodify the color that is displayed for each channel in the .cpt file. After a .cpt filehas been chosen by the user, selecting Assign Colors to Channel Groups willopen this dialog box:


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There is an option in the map layers dialog for Transmitter/Base/Hub sites thatdisplays a user-specified color for the channel that is assigned to that sector.

The service area boundary file may be in either the .BNA or .MIF format and shouldbe a simple polygon describing the geographic area in which the system is beingdesigned. This polygon file may be easily created with the Draw polygon menu tool.

1.6. Preamble Code Planning

In a WiMAX network, each sector is assigned a preamble code that is used for cellsite recognition at the remote unit. It is important to assign codes that do notinterfere with each other at the remote, which depends on the code assigned to each

sector, the relative signal strength of the sectors, and the time delay between them.The preamble code planning dialog allows preamble codes to be assignedautomatically based on these criteria. Codes in the Excluded PN codes list will notbe assigned, allowing them to be left out of the system design or reserved for laterallocation. To run this feature youll need to have the WiMAX sectors set up withchannel and segment index assigned to them. Once this is done, specify a desiredC/(I+N) ratio and click the Assign PN codes to all unlocked sectors button.TheAssignment order random seed value can be changed to vary the order inwhich codes are assigned.


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Once the preamble code planning feature has run successfully, the channels dialogof each sector should showPN code and Cell ID code. A text list of the assignedPN codes and Cell IDs can then be found in the projects cache folder. UseNetworkDesign/Analysis >WiMAX systems > System Reports to view a listof sectors to which a code could not be assigned due to excessive interference fromother sectors.

1.7. Neighbor Lists

Neighbors in a cell system are other cell base stations or sectors that have signalsof sufficient strength in the service area of another cell base station or sector wherethey are candidates for call handoff. Normally neighbor lists are part of theinformation that is stored at the cell site and may be downloaded to the mobile unitto facilitate handoff from the currently serving base station to another base station.

The neighbor list calculation in theNetwork Design Module: WiMAX Systemsmodule isintended as a simple means of determining which sectors are neighbors, and thereby,handoff candidates. In the dialog box you can set the maximum number of

neighbors you want listed, and whether to include the 2nd

and 3rd

best servers in thelist. You can also select the transmitter group and the mobile/remote unit ID forwhich you want the neighbor list study done.


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When these parameters are set the way you want them, click on the Calculateneighbor lists for all sectors button and the calculation process will begin.Fundamentally, the program assesses the service area of each sector, and for theanalysis grid points within this service area, determines which other transmittersectors can be considered to be the neighbor cell base stations or sectors to whichhandoffs are likely.

In the dialog box set the minimum percent area of the primary server that needs tobe covered by another server in order for the other server to be considered aneighbor. You can optionally include the 2nd and 3rd best servers in the list and notinclude co-channel neighbors (same channel or frequency). Select the transmittergroup for which you want the neighbor list study done.

There is also a selection as to how to select and rank sectors for determination ofthem as a server or neighbor. Power Received ranks them based on power at theRemote unit whereas C/(I+N) Best Channel looks for the best possible C/(I+N) ofa server using one of its assigned channel plan channels (this option is intended forsystems other than WCDMA/UMTS). The signal thresholds at which a server canbe considered a neighbor is set by the Remote/Mobile Unit Required ServerThreshold or Required Service C/(I+N). The unit used by this study is alwaysRemote/Mobile unit "Mobile1".

When the analysis is complete, the neighbor list is applied to the information foreach cell base station or sector. It can be viewed by selecting the Neighbor Listbutton on the Transmitter Details dialog box as described in Chapter 9 of theReference Manual. There is also an option in this dialog box to copy the predictedneighbor list directly into each WiMAX sector in the selected group.


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There are more complicated ways to calculate predicted neighbor lists, however thesimple method used here is largely as effective as other methods and provides for avery rapid calculation time.

1.8. Frequency PlanningWith the traffic load calculated for each cell base station or sector, it is now possibleto assign the appropriate number of channels to each sector to handle this traffic. Ifyou have a small system, or a simple system layout, assigning channels can be donemanually as described in Section 3.2 of the Reference Manual, Network Design Module:Mobile and Nomadic Systemssection of the manual, using the guidelines provided there.

If your system is large or complicated, the automatic frequency planning capabilitiesof theNetwork Design Module: WiMAX Systemscan be used. This process is describedin the following sections.


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1.8.1. Frequency Planning ParametersSeveral parameters are required to do a successful frequency plan. These are

explained below:

1.8.1.1. C/I Ratio ObjectiveThis parameter is only used for frequency planning options 2 and 3 below. In doinga frequency plan, the first step is to determine which sectors are geographically closeenough (in radio propagation terms) to potentially cause interference to one another.The threshold of determining what constitutes interference for this purpose is sethere.


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1.8.1.2.Percent Interference AcceptanceWhen a frequency plan is done, it cannot perfectly assign the channels so that all theinterference conflicts are resolved and all the traffic is accommodated. Thisparameter tells the program that the maximum percentage of a sectors service area(i.e. the area where it is the strongest signal) which can be lost to interference is thispercentage value. A typical value here is 5 or 10 %.

1.8.1.3. Use Measured Interference matrix fileFrequency assignments are normally done using interference that is calculated usingthe propagation model for each interfering sector. However if you have switch ordrive test data that can define the interference for each sector, this can used bychoosing this option. The name and location of this file is entered in the DefineSystem/Service Area window and selecting the Other System Parameters . Themeasured interference data entered into this file must follow the format describedbelow:

siteid_serv(1), num_intrf(1)

siteid_intrf(1), signal_level_ratio(1), std_dev(1)

siteid_intrf(2), signal_level_ratio(1), std_dev(1)siteid_intrf(3), signal_level_ratio(1), std_dev(1)

.

.

siteid_intrf(num_intrf),signal_level_ratio(num_intrf),std_de

v(num_intrf)

.

.

siteid_serv(num_serv), num_intrf(num_serv)

where:

siteid_serv t he si t e I D of t he ser vi ng sect or encl osed i nsi ngl e quotes ( ex, AAAA0001 )

num_intrf t he number of i nt er f er i ng sect or s l i st ed f ort hi s ser vi ng sect or

siteid_intrf t he si t e I D of an i nt er f er i ng sect or encl osedi n si ngl e quot es

signal_level_ratio t he mean measured si gnal l evel r at i o i ndB between t he i nt erf eri ng sect or and t he servi ng sect or

std_dev t he st andard devi ati on i n dB of t he si gnal l evelr ati os assumi ng a normal di st r i but i on

num_serv t he number of servi ng sector s wi t h i nf ormati on i nt hi s f i l e

1.8.1.4. Traffic SourceWhen using Internal automatic frequency planning, as described below, thetraffic source that determines system loading can be specified. For WiMAX the datatraffic options are used. Either predicted or measured traffic can be selected. Thesetraffic figures are drawn from the appropriate entry found in each transmittersectors Channel Grid dialog box. The traffic value used for planning can be scaledup or down by entering a number other than 100% in the Percent of total trafficfor planning box.


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1.8.1.5.Deny Co/Adj channels at siteThese two options allow you to restrict the assignment of adjacent channels and/orco-channels to sectors at the same base site. Typically co-channels are neverassigned to different sectors at a site unless the channel re-use is one.

1.8.1.6.Minimum Channel Separation at SiteIn some systems, even adjacent channels do not provide sufficient isolation betweensectors. This value allows you to set the minimum channel spacing betweenchannels assigned to sectors at the same base site. Zero is the default.

1.8.1.7.Assign Fixed Number of ChannelsNormally the number of channels per sector is determined by the estimated trafficload at the sector. If this information is not available this option allows you assign afixed number of channels at each sector.

1.8.2.Automatic Frequency Planning (AFP)There are three methods of WiMAX automatic frequency planning (AFP) available

in the Network Design Module: WiMAX Systems. These three methods are discussedbelow.

1.8.2.1.InternalWhen you select Internal, you will invoke EDXs method for AFP. This methodprovides for interference conflict resolution as well as balancing channels assignedto sectors to match traffic demand.

When using Internal (or External), the first step the program performs is tocalculate a sector compatibility matrix. This is done only inside the service area asdefined by the service area boundary fi le entry on the Define System and ServiceArea dialog box. Inside this boundary, the program will calculate and define the

service areas for each sector as those locations where that sector provides thestrongest signal. Only those sectors whose signal exceeds the Required ServiceThreshold found in the user-selected Remote/Mobile Unit will be considered.

Next it will look at the signal levels inside each sectors service area and determinethose which are strong enough that the C/(I+N) ratio objective is violated (seeSection 3.3.2.1). It will track all those areas where this ratio is violated for each sectorand the sectors that cause the interference. It will then calculate the degree ofinterference each other sector causes by calculating the percent of interferencelocations as a function of the total service area for the victim sector.

Finally, based on the service area of each sector, it will determine the traffic load

from the areas served by that sector (see the options in Section 3.3) and, using theGoS, calculate the number of voice channels needed at that sector using the ErlangB formula or in the case of packet-switched traffic the number of channels based ondata/channel.

The results of this processing are written to an ASCII data file called cellcmpx.dat.This is the basic data that the AFP optimization will use to do its work. The formatof the cellcmpx.dat file is as follows:


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EDX cell sector AFP compatibility matrix

num_sectors cinr accept_intrf minutes_per_call

blocking_prob

siteid_serv serv_area calls traffic num_chan_req

num_chan_assigned ky_lock

nchan(1) nchan(2) nchan(3) . . .

. . . . nchan(num_chan_assigned)

siteid_intrf(1) prcnt_intrf(1)



.

.

.

siteid_intrf(num_sectors-1) prcnt_intrf(num_sectors-1)

where:

EDX . . . - header l i ne t o i dent i f y t he f i l e

num_sectors t he number of sect or wi t h i nf ormat i on i n t hi sf i l e

cinr t he obj ecti ve C/ ( I +N) r at i o

accept_intrf t he percent of i nt erf erence whi ch can beaccept ed i n a sector servi ce ar ea

minutes_per_call t he aver age cal l dur ati on i n mi nut es

Blocking_prob t he per cent bl ocki ng pr obabi l i t y

Siteid_serv t he I D of t he servi ng sect or

Serv_area t he t ot al ar ea f or t hi s ser vi ng si t e squar eki l ometer s

calls - t he number of cal l s per hour f or t hi s sect or

traffic t he r equi r ed t r af f i c l oad f or t hi s sector

num_chan_req t he number of channel s r equi r ed t oaccommodat e t he t r af f i c gi ven t he GOS.

num_chan_assigned t he number of channel s cur r ent l yassi gned t o thi s sect or .

ky_lock t hi s equal s 1 i f t he channel l ock checkbox i schecked on t he channel pl an scr een f or t hi s sect or. Thesemeans t he cur r ent assi gnment s f or t hi s sect or ar e to remai nunchanged.

nchan(1), nchan(2) . . . t he channel numbers cur r ent l yassi gned t o t hi s sect or. I f t he channel assi gnment s on t hi ssector are l ocked, t hen t he AFP al gori t hm must pr eser ve t hi schannel assi gnment l i st and prot ect i t f r om i nt er f erencedur i ng t he AFP pr ocess.

siteid_intrf t he I D of t he i nt er f er i ng sect or

prcnt_intrf t he per cent of t he t ot al ser vi ng sect orser vi ce ar ea t hat i s i nt erf er ed wi t h by t hi s i nt er f er i ngsect or . Thi s number i s a rel at i ve i ndi cat i on of degr ee ofconf l i ct bet ween t he ser vi ng sect or and t hi s i nt er f er i ngsector.


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The above information is listed once in the cellcmpx.dat file for each sector in thesystem.

With the information in this file, and the cell channel plan template showing thenumber of available channels, the EDX AFP algorithm is ready to do its work.

Basically, it attempts to devise channel assignments for each sector so that the trafficdemand is met while at the same time making channel assignments so that no sameor adjacent channels are used between sectors that have conflicts. The basictechnique it uses is called simulated annealing (SA), which is a combinatorialoptimization process.

With simulating annealing (SA), there are several parameters that are used to controlthe process. Typical values are:

number of cooling levels = 300cooling level step multiplier = 0.85number of iterations at each cooling level = 900co-channel cost weighting coefficient = 1.00adjacent channel cost weighting coefficient = 0.01interference cost weighting coefficient = 1.00demand cost weighting coefficient = 1.00

You can adjust these parameters if desired for your particular optimization. Beforedoing so, however, it would be worthwhile to review references [3] and [4] tounderstand the significance of the parameters.

Depending on the number of sectors, and the parameter settings, this process couldtake from several minutes to several hours to complete. When completed, theprogram will return with a message asking you to accept or reject the channel planthat has been produced by the AFP process. The channel assignment results will be

contained in an ASCII data file called chanplan.tmp. If accepted, thechanplan.tmp file is read by EDX software and those channel assignments loadedinto the channel plan dialog box data positions for each sector. From that pointforward you are ready to begin coverage and interference studies with your newoptimized channel assignment plan.

1.8.2.2.ExternalExternal basically gives you access to an external dynamic link library (DLL) whichcontains your own compiled and linked code for doing the AFP. Before calling thisroutine, the Network Design Module: WiMAX Systemsperforms all the calculations tocreate the cellcmpx.dat file as described above. It then passes this file name andthe other relevant file names to the external AFP routine. When this routine is

completed, the channel assignment results are written to an ASCII file calledchanplan.tmp from which the channel assignments are imported back into EDXSignalPro.

The details of how the parameters are passed to the external routine, and therequired format for the resulting channel assignment file, are found in the commentstatements in the sample ext_afp.for code included on the distribution CD.Appendix Jalso has for more information on using this and other external calculationDLLs withEDX SignalPro.


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1.9.Traffic Planning for WiMAX systems

WiMAX is based on an all-IP network, which uses packet-switched trafficdefinitions. Most internet traffic, such as web browsing, FTP and e-mail (which isdefined as BE or Best Effort for WiMAX) allow the packets that cant be sent dueto capacity limitations to not be permanently blocked but delayed until network

capacity is available. Packet traffic that is associated with VoIP calls, videoconferencing or IPTV (Internet Television) is defined as UGS or UnsolicitedGrant Service for WiMAX. These packets, if they cant be sent within a very narrowtimeframe, are dropped, since their time-sensitive nature makes late UGS packetsuseless.

To specify traffic loading for the WiMAX sectors, select NetworkDesign/Analysis > Packet Switched Traffic Loading > WiMAX/BWA. This willdisplay a dialog box where you can set both the traffic definitions (types of packettraffic, and their associated average data rates and activity percentages) as well ashow the subscriber devices are distributed in the WiMAX system.

Selecting the Packet Switched Traffic Loading menu for WiMAX brings up thisdialog box:

1.9.1.Traffic Data SourceThere are four traffic data sources, or distributions, which can be selected:

Uniform Traffic Distribution. A uniform distribution is where the probability oftraffic originating from a given place inside the cell system service boundary is


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assumed to be equal. In other words, the subscriber devices are spread evenlythroughout the defined service area.

Traffic based on Land Use (Clutter) Database. If you select this traffic datasource, the distribution of traffic will be weighted according to the land use ormorphology category. Typical there will be more calls or data originating from urban

areas than agricultural areas, for example. To use this option you must havespecified a land use (clutter) database as described in Chapter 10 of the ReferenceManual.

Traffic based on demographic database. If you select this option, the traffic willbe weighted according to the population in a given region of your cell system servicearea. To use this option you must have specified a demographic database asdescribed in Chapter 10 of the Reference Manual.

Traffic from traffic database. If you select this option, the traffic will be weightedaccording to actual traffic density valued in a traffic database in a given region ofyour cell system service area. The type of traffic to be calculated in the system is

defined by the type of data stored in this database. If it is voice traffic the data willbe expressed in milliErlangs. If it is packet data then the traffic will be in Kbps. Touse this option you must have specified a traffic database as described in Chapter 10of the Reference Manual.

1.9.2. Packet Switched Traffic Definitions and DensitiesThe Packet switched traffic definitions are specified in the dialog box as shownbelow:

This table allows the user to define up to five different types of service types alongwith their service flow (typically UGS or BE, but rtPS, ntPS and ErtPS are alsoavailable choices), average downlink and uplink data rates and activity percentages(only applicable for rtPS, ntPS or BE). If the Service Name is left blank, then theinformation associated with that column of data will not be used in traffic studies.

The defined (named) service types in the Packet Switched Traffic Definitions dialogbox are automatically copied over to the Packet Switched Traffic Densities dialogbox, which is shown below:


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This dialog box allows the user to specify the subscriber traffic distribution for eachservice type, based on the Percent of total traffic to be carried by this groupsetting in the main Packet Switched Traffic Loading dialog box.

The main Traffic Loading dialog box is where the user can have the total packet

switched traffic load calculated for each WiMAX sector in the user-specifiedTransmitter Group.

1.10.WiMAX Studies

As mentioned earlier, there are a number of area studies found in the area studiesWiMAX/Wireless Broadband study group. The ones specific to WiMAX aredetailed below:

WiMAX OFDMA Modulation Regions-DL This study displays the achievablemodulations with which a user in a specific location can be reached on thedownlink. The estimated modulations are computed based on the propagation

model selected in the program and the C/I equipment thresholds that are set in theRF Systems > Adaptive Modulation dialog. Selecting this area study also createsa usage report as explained in the next section.

WiMAX OFDMA Modulation Regions-UL This area study predicts themodulation of the connections from a given user in the service area on the uplink.The modulations are color coded and displayed as a coverage map. The user hasthe option of choosing sector-specific WiMAX stochastics uplink predictedinterference levels in the dialog box accessed in Studies > Noise and Uplink


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Interference. The predicted uplink interference levels are then stored for eachWiMAX sector and can be used in this study when the user selects interferenceonly or noise plus interference in the study setup dialog box.

WiMAX Maximum Uplink C/(I+N) The uplink C/(N+I) at each sector isplotted geographically based on the remotes location within the cell. This plot

evaluated byEDX SignalPro corresponds to the combined effect of the worst caseuplink C/(I+N) from all co-channel sources. There are two potential sources ofinterference on the uplink in a WiMAX system; the subscribers in co-channelsectors and the interferences from unsynchronized base stations (from a secondtransmitter group). Both, one, or none of these sources of interference can beincluded in the worst C/(I+N) uplink study. These sources of interference can beconsidered in the analysis by checking their corresponding box after pressingmodify study button (see below). The text report that is produced by this studyincludes valuable information of the worst interferers in the neighboring cells thatare worth consideration.

WiMAX Average Uplink C/(I+N) study The user has the option of choosing

sector-specific WiMAX stochastics uplink predicted interference levels in the dialogbox accessed in Studies > Noise and Uplink Interference. The predicted uplinkinterference levels are then stored for each WiMAX sector and can be used in thisstudy when the user selects interference only or noise plus interference in thestudy setup dialog box. This study calculates the C/(I+N) for each point based onthe predicted uplink interference levels at each WiMAX base station sector in thestudy group.

WiMAX Interference for Focus Sector This displays a map of the areas inneighboring co-channel sectors that produce uplink interferences greater than 3dBbelow noise floor. Subscriber stations in these areas produce the largest interferenceson the uplink. The interference levels are displayed geographically so that a systemplanner can choose to mitigate their effects by using antenna down tilting, channel

planning, or other methods.

Strongest (most likely) Server using best channel. This study map displays thecolors and symbols that correspond of the sector that has the highest C/(I+N) ineach grid square.

2nd Strongest Server at Remote: The second strongest server is automaticallydetermined when the program finds the strongest servers as described in SectionF.1.10. inAppendix F. Consequently, when the user elects to display this study type,the calculations are the same and the map simply displays the colors and symbolsthat correspond to the 2nd strongest server sector rather than the strongest server,which is displayed in the strongest (most likely) server basic study. For either study

type, as you move the pointer around the map, the ID and signal strength from boththe first and second strongest servers will be continuously displayed.

C/(I+N) at Remote for Best Channel. This study map displays the colors andsymbols that are associated with the C/(I+N) that correspond to the sector that hasthe highest C/(I+N) in each grid square.

Adaptive modulation downlink data rate. This study determines the modulationand coding as well as the user specified data rate for each grid square based on the


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predicted C/(I+N) and the data in the downlink WiMAX Adaptive Modulationtable that is accessed through the WiMAX System Details dialog box at NetworkDesign/Analysis > WiMAX Systems > System details /Service area.

Adaptive modulation uplink data rate. This study determines the modulationand coding as well as the user specified data rate for each grid square based on the

predicted C/(I+N) and the data in the uplink WiMAX Adaptive Modulation tablethat is accessed through the WiMAX System Details dialog box at NetworkDesign/Analysis > WiMAX Systems > System details/Service area. The userhas the option of choosing sector-specific WiMAX stochastics uplink predictedinterference levels in the dialog box accessed in Studies > Noise and UplinkInterference. The predicted uplink interference levels are then stored for eachWiMAX sector and can be used in this study when the user selects interferenceonly or noise plus interference in the study setup dialog box.

WiMAX Uplink Interference Stochastics. This study attempts to quantify uplinkinterference prediction using statistical (probabilistic) methods. Based on the user-specified subscriber traffic definitions and densities, the stochastic study analyzes the

probability that any given subscriber device will interfere with other co-channelWiMAX base stations based upon their propagation characteristics and the durationof the subscriber devices transmissions. Since the probability that one of subscriberdata uplink transmission to its serving cell will be interfered by a co-channel userserved by another sector is simply the frame fraction of the subscriberstransmission the fraction of the total WiMAX frame in the subscriberstransmission. The WiMAX uplink interference stochastics study determines sum ofthese frame fraction probabilities for each WiMAX sector based on its specifiedsubscriber traffic. This study produces a plot showing the percentage of the sectorsframe that should be clear of interference in each grid square. This study also showsthe uplink desired (coverage) and undesired (interference) statistics, along with a plotby right mouse clicking over the site of interest and choosing from the pull-downmenu the sector of interest at that site and in the submenu for that sector, the

Receiver Power Profile. This is shown below.


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This will show a plot like this shown below:

This plot not only shows the distribution of the undesired (interfering) signals as redpoints with their IX (interference) mean and IX standard deviations calculated andalso shown but the distribution of the desired uplink signals at the WiMAX basestation and their associated mean and standard deviation as blue points. The placesin the curve where the points overlap is the percentage of the frame fractions thatare unusable in a sector.

The user has the option to store this per-sector predicted uplink interference level inthe Studies > Noise and Uplink Interferencemenu, which has options to store


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either the 50% or 90% predicted uplink interference level from the uplinkStochastics study.

1.11.WiMAX Study System Reports

This option will display a list of available system reports that may be generated whenrunning certain specialized studies. To open a report, select it from the list and clickView Report. This will open the text file in the default text editor, typicallyWindows Notepad. These report files are stored in the \REPORTS sub-folderof the Project folder.

WiMAX Uplink C/(I+N) creates the WiMAX_Uplink_Interference_Details.txtreportfile. This file contains the strongest interferences from neighboring co-channelsectors as long as they are stronger than 3dB below the noise floor. These co-channel interferences can be from either unsynchronized base stations or remotes.

The channel usage reports created by theWiMAX OFDMA Modulation Regions-DL and WiMAX OFDMA Modulation Regions-UL area studies have a similarformat. These two studies create the text files WiMAX_Downlink_Usage.txt andWiMAX_Uplink_Usage.txt respectively. EDX SignalPro computes the number ofslots available for assignment from the OFDMA parameters on the uplink anddownlink assuming the PUSC sub-channelization scheme. The base station canallocate these slots on the UL and DL to the different users in the cell. The numberof slots used by each user is a function of its demand and with which modulation

order it communicates with the base station. EDX SignalPro estimates the numberof slots used per sector by taking into account the location and densities of users inthe service area. The distribution of users can be set under the Packet Switchedtraffic loading menu.


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The usage or loading results of WiMAX are reported in a text file every time an ULor DL WiMAX OFDMA Modulation Regions area study is run. The results arelisted on a sector-by-sector basis so that the demand in each sector can bemonitored individually.


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