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EDX Software

Reference ManualNetwork Design

Module:

Positive TrainControl Systems


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EDX Wireless NDM: PTC Systems ReferenceManual Table of Contents

i

Reference ManualNetwork Design Module:

Positive Train Control SystemsTable of Contents

1. Positive Train Control (PTC) Systems1.1. What is the PTC Section of the Network Design Module? ................................................. NDM-PTC 11.2. Installing the Network Design: PTC Systems Module ......................................................... NDM-PTC 21.3. Starting a PTC System Design .................................................................................................. NDM-PTC 21.4. Accessing the Network Design Module: PTC Systems Functions ..................................... NDM-PTC 21.5. System Details / Service Area ................................................................................................... NDM-PTC 41.6. Neighbor List Prediction ........................................................................................................... NDM-PTC 51.7. Automatic Frequency Planning................................................................................................. NDM-PTC 71.7.1. Frequency Planning Parameters ........................................................................................... NDM-PTC 81.7.2. Automatic Frequency Planning (AFP) ................................................................................ NDM-PTC 9

1.8. PTC Studies ................................................................................................................................ NDM-PTC 131.8.1. Handoff regions for PTC systems ..................................................................................... NDM-PTC 131.8.2. Worst channel C/(I+N) for multiple-channel systems .................................................. NDM-PTC 141.8.3. Maximum available Downlink data rate for PTC systems ............................................. NDM-PTC 141.8.4. Maximum available Uplink data rate for PTC systems ................................................. NDM-PTC 15


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EDX Wireless NDM: Positive Train Control Systems Reference Manual NDM-PTC 1

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

1. Positive Train Control

(PTC) Systems1.1. What is the PTC Section of the Network Design

Module?

The Network Design Module is an optional EDX software module connected to EDX

SignalPro. The Positive Train Control (PTC) Systems Section of the Network Design Module

(NDM-LTE) gives you the advanced, specialized system engineering capabilities needed

to design, re-configure, and optimize PTC wireless networks using route study methods.

The NDM-PTCcontains special data entry dialog boxes in which you can specify the

particular PTC system profile in use along with other details pertaining to that system as

well as allowing access to special area studies for those system types.

In performing its tasks, this module makes use of many basic signal level calculation

techniques that are accessed through EDX SignalPro. A cell site sector (whether omni-

directional or sectorized), is analogous to a transmitter site in EDX SignalPro. When you

run an PTC study, the program will extract terrain and land-use (clutter) data, calculate

signal levels along a user-defined study route, and build a composite route study in the

same way it does in the main program for a transmitter site (see Section 8.5for the main

Reference Manual). It will create .rte files for each cell sector just as it did for eachtransmitter site. It is helpful to reviewSection 8.4 for more background on this process.

This module also relies on the database settings that are made in the main EDX

SignalPro program. Setting up terrain, land use (clutter), traffic, and demographic

databases that are used by the NDM-PTC is done on the Databases menu from the

Main Map menu.

You can also use the extensive mapping and drawing capabilities in EDX SignalPro to

create very detailed and informative base maps for your PTC system studies. Detailed

base maps are an important tool for determining where cell sites may be located, judging

where system capacity may be insufficient (or under-utilized), and gauging 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).


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NDM-PTC 2 EDX Wireless NDM: PTC Systems


Because the NDM- PTC offers specialized add-on capabilities, it is important to be

fluent with the basic operation and functions ofEDX SignalPro before attempting to use

this module.

1.2. Installing the Network Design: PTC Systems

Module

The capabilities of this module are automatically installed when you install EDX

SignalPro with theNetwork Design Moduleor when you installEDX SignalRail, as described

in Chapter 1 of the Reference Manual. There is no separate installation to be done. The

module code is built into the program and the hardware key you receive contains the

proper authorization codes to activate theNetwork Design Module: PTC Systems. To verify

that the module is properly installed, select Help/About on the EDX SignalPro main

menu. It will indicate whether or not the module is installed.

1.3. Starting a PTC System Design

The standard EDX SignalPro program stores information for a study in the project

directory. This directory contains all the parameters and other information needed to

completely reproduce a study map on your screen when you open a selected project.

The project includes the specific parameters for each of your transmitter sites/sectors,

or links, as well as information about the databases, propagation models, and base map

features. Projects are explained in Chapter 3 of the Reference Manual.

The material in thisNDM-PTCreferencemanual is presented assuming you have already

read the Users Guideand the Reference Manualthat are included with your software. If youhave not done so, please review these materials before moving on to the functions

described in the following chapters.

1.4. Accessing the Network Design Module: PTCSystems Functions

If you have started a new project, or opened an existing one, the Network Design Module:

PTC Systems functions will be available to you. To access Network Design Module: PTCSystems, select the NetworkDesign/Analysis item on the main EDX SignalPro menu,

then select PTC Systems. A sub-menu will appear showing the various elements

provided by the module for this system type. There will also be an additional category of

studies available when a new area study is added to a project.


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TherearethreePTCNDMmenus: SystemDetailsandServiceArea NeighborListprediction AutomaticFrequencyPlanning


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1.5. System Details / Service Area

The PTC NDM System Details dialog box is shown below:

There are three PTC system Technology Types that the user can choose:

PTC NXDN

PTC GSM-R

PTC - TDMA/CSMA

Handoff criteria can also be specified. The user has the option of specifying whether

the handoffs are to be modeled using absolute levels or power ratio (better server). The

user also can specify the thresholds used to determine handoffs.


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In the other Network Design Modules, the user specifies a Service Area Boundary

polygon file. For route based planning, the user has the option to either select the same

study route that is defined for their route studies or to select a unique study route for

Neighbor List predictions and Automatic Frequency Planning. Defining Study Routes is

explained in section 8.4 of the Reference Manual.

A CPT (Channel Plan Template) file needs to be specified. It is used to select available

channels, either manually by the user or through Automatic Frequency Planning.

1.6. Neighbor List Prediction

Neighbors in a cell system are other cell base stations or sectors that have signals of

sufficient strength in the service area of another cell base station or sector where they

are candidates for call handoff. Normally neighbor lists are part of the information that

is stored at the cell site and may be downloaded to the mobile unit to facilitate handofffrom the currently serving base station to another base station.

The neighbor list calculation in the Network Design Module: PTC Systems module is

intended 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 the list. You can

also select the transmitter group and the mobile/remote unit for which you want the

neighbor list study done. The user also has the option to copy the predicted neighbors

into the actual neighbor list for all transmitters in the user-specified group. The NDM

Neighbor list generation will use the study route defined in the PTC NDM System

Details dialog box for generating neighbors for sites. The dialog box for the PTC

NDM Neighbor List looks like this:


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When these parameters are set the way you want them, click on the Calculate

neighbor lists for all sectors button and the calculation process will begin.

Fundamentally, the program assesses the service area of each sector, and for the analysis

study route points, determines which other transmitter sectors can be considered to be

the neighbor cell base stations or sectors to which handoffs are likely

In the dialog box set the minimum percent area of the primary server that needs to be

covered by another server in order for the other server to be considered a neighbor. You

can optionally include the 2nd and 3rd best servers in the list and not include co-channel

neighbors (same channel or frequency). Select the transmitter group for which you want

the neighbor list study done.

There is also a selection as to how to select and rank sectors for determination of them

as a server or neighbor. Power Received ranks them based on power at the Remote unit

whereas C/(I+N) Best Channel looks for the best possible C/(I+N) of a server using

one of its assigned channel plan channels. The signal thresholds at which a server can

be considered a neighbor is set by the Remote/Mobile Unit Required Server Threshold

or Required Service C/(I+N).

When the analysis is complete, the neighbor list is applied to the information for each

cell base station or sector. It can be viewed by selecting the Neighbor List button on the

Transmitter Details dialog box as described in Chapter 9of the Reference Manual.


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There are more complicated ways to calculate predicted neighbor lists, however the

simple method used here is largely as effective as other methods and provides for a very

rapid calculation time.

1.7. Automatic Frequency Planning

If your system is large or complicated, the automatic frequency planning capabilities of

the Network Design Module: PTC Systems can be used. This process is described in the

following sections. The PTC NDM AFP dialog box is as shown below:


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1.7.1. Frequency Planning Parameters

Several parameters are required to do a successful frequency plan. These are explained

below:

1.7.1.1. C/I Ratio ObjectiveThis parameter is only used for the Internal and External frequency planning options

below. In doing a frequency plan, the first step is to determine which sectors have

strong enough signal levels to potentially cause interference to one another. The

threshold of determining what constitutes interference for this purpose is set here.

1.7.1.2. Percent Interference AcceptanceWhen a frequency plan is done, it cannot perfectly assign the channels so that all the

interference conflicts are resolved and all the traffic is accommodated. This parameter

tells the program that the maximum percentage of a sectors service area (i.e. the areawhere it is the strongest signal) which can be lost to interference is this percentage value.

A typical value here is 5 or 10 %.

1.7.1.3. Traffic SourceWhen using the Internal planning option as described below, the traffic source that

determines system loading can be specified. For PTC the Data traffic options are used.

Either predicted or measured traffic can be selected. These traffic figures are drawn

from the appropriate entry found in each transmitter sectors Channel Grid window.

The traffic value used for planning can be scaled up or down by entering a number

other than 100% in the Percent of total traffic for planning box.

1.7.1.4. Deny Co/Adj channels at siteThese two options allow you to restrict the assignment of adjacent channels and/or co-

channels to sectors at the same base site. Typically co-channels are never assigned to

different sectors at a site unless the channel re-use is one.

1.7.1.5. Minimum Channel Separation at SiteIn some systems, even adjacent channels do not provide sufficient isolation between

sectors. This value allows you to set the minimum channel spacing between channels

assigned to sectors at the same base site. Zero is the default.


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1.7.1.6.Assign Fixed Number of ChannelsNormally the number of channels per sector is determined by the estimated traffic load

at the sector. If this information is not available this option allows you assign a fixed

number of channels at each sector.

1.7.2.Automatic Frequency Planning (AFP)

There are two methods of automatic frequency planning (AFP) available in theNetwork

Design PTC Systems, Internal and External. These three methods are discussed below.

1.7.2.1. InternalWhen you select Internal , you will invoke EDXs method for AFP. This method

provides for interference conflict resolution as well as balancing channels assigned to

sectors to match traffic demand.

When usingInternal (or External), the first step the program performs is to calculate a

sector compatibility matrix. This is done only for the study route points that are

specified in the Define Study Route dialog in the PTC System Detailsdialog box.

For the user-specified study route points, the program will calculate and define the

service areas for each sector as those study route points where that sector provides the

strongest signal. Only those sectors whose signal exceeds the Required Service

Threshold found for the specified Remote/Mobi le Unit will be considered.

Next it will look at the signal levels for the study route points in each sectors servicearea and determine those which are strong enough that the C/(I+N) ratio objective is

violated. It will track all those study route points where this ratio is violated for each

sector and the sectors that cause the interference. It will then calculate the degree of

interference each other sector causes by calculating the percent of interference locations

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 and using for packet-switched traffic, the number of

channels based on data/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 format of

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 line to identify the file

num_sectors the number of sector with information in this file

cinr the objective C/(I+N) ratio


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accept_intrf the percent of interference which can be accepted in a sector service area

minutes_per_call the average call duration in minutes

Blocking_prob the percent blocking probability

Siteid_serv the ID of the serving sector

Serv_area the total area for this serving site square kilometers

calls - the number of calls per hour for this sector

traffic the required traffic load for this sector

num_chan_req the number of channels required to accommodate the traffic given

the GOS.

num_chan_assigned the number of channels currently assigned to this sector.

ky_lock this equals 1 if the channel lock checkbox is checked on the channel plan

screen for this sector. These means the current assignments for this sector are to remain

unchanged.


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nchan(1), nchan(2) . . . the channel numbers currently assigned to this sector. If the

channel assignments on this sector are locked, then the AFP algorithm must preserve

this channel assignment list and protect it from interference during the AFP process.

siteid_intrf the ID of the interfering sector

prcnt_intrf the percent of the total serving sector service area that is interfered with

by this interfering sector. This number is a relative indication of degree of conflict

between the serving sector and this interfering sector.

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

system.

With the information in this file, and the cell channel plan template showing the number

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 traffic demand is met

while at the same time making channel assignments so that no same or adjacent

channels are used between sectors that have conflicts. The basic technique it uses is

called simulated annealing (SA), which is a combinatorial optimization process.

With simulating annealing (SA), there are several parameters that are used to control the

process. Typical values are:

number of cool i ng l evel s = 300

cool i ng l evel st ep mul t i pl i er = 0. 85

number of i t er at i ons at each cool i ng l evel = 900

co- channel cost wei ght i ng coef f i ci ent = 1. 00

adj acent channel cost wei ght i ng coef f i ci ent = 0. 01

i nt er f er ence cost wei ght i ng coef f i ci ent = 1. 00

demand cost weighting coefficient = 1.00


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You can adjust these parameters if desired for your particular optimization. Before doing

so, however, it would be worthwhile to review references on Simulated Annealing to

understand the significance of the parameters.

Depending on the number of sectors, and the parameter settings, this process could take

from several minutes to several hours to complete. When completed, the channel

assignment results will be contained in an ASCII data file called chanplan.tmp. The

chanplan.tmp file is read byEDX softwareand those channel assignments loaded into

the channel plan dialog box data positions for each sector in the group selected for

Automatic Frequency Planning. From that point forward you are ready to begin

coverage and interference studies with your new optimized channel assignment plan.

1.7.2.2. ExternalExternal basically gives you access to an external dynamic link library (DLL) which

contains your own compiled and linked code for doing the AFP. Before calling this

routine, the Network Design: PTC Systems performs all the calculations to create the

cellcmpx.dat file as described above. It then passes this file name and the other

relevant file names to the external AFP routine. When this routine is completed, the

channel assignment results are written to an ASCII file called chanplan.tmp from

which the channel assignments are imported back intoEDX SignalPro.

The details of how the parameters are passed to the external routine, and the required

format for the resulting channel assignment file, are found in the comment statements in

the sample ext_afp.for code included on the distribution CD. Appendix Jalso has for

more information on using this and other external calculation DLLs with EDXSignalPro.

1.8. PTC Studies

In addition to the Basic Studies that are defined in Appendix F, the following studies are

available for the PTC Network Design Module:

1.8.1. Handoff regions for PTC systems

The map of handoff regions is calculated in one of two ways. If you have selected

Abso lute level as the handoff type on the PTC System Details dialog box, then the

handoff map will show areas where there are two or more signals that fall within the

signal level range between the handoff level and the minimum useable level as set on the

PTC System Details dialog box.


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If you selected Power ratio as the handoff method, then the handoff map will show

those areas where the ratio between the strongest and second strongest server is equal to

or less than the power ratio value you enter on the PTC System Details dialog box.

1.8.2.Worst channel C/(I+N) for multiple-channel systems

This study calculates interference statistics for multi-channel systems. This study will

evaluate each assigned channel for each transmitter in the group of transmitters that the

study is run for. This study produces a C/(I+N) plot of the most interfered with

channel for the serving sector in each grid square. This study also produces a report that

describes the interference statistics for each assigned channel of each transmitter

1.8.3. Maximum available Downlink data rate for PTCsystems

This study calculates the maximum available downlink data rate for PTC systems based

on the predicted downlink C/(I+N) at each route point. This requires the use of an

external data file named ptc_data_rate.dat that is installed in the EDX program files

installation \Data subdirectory. This file format is explained below:

'TDMA CSMA'

6

25.0 50.0 35.0

20.0 45.0 31.0

15.0 35.0 25.0

12.0 25.0 15.0

8.0 12.0 8.0

5.0 5.0 1.0


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Note that each data line needs to be ordered from the highest minimum C/(I+N) to the

lowest usable C(I+N).

1.8.4. Maximum available Uplink data rate for PTC systems

This study is similar to the Maximum available Downlink data rate for PTC systems

study except that it calculates the maximum available uplink data rate for PTC systems

based on the predicted uplink C/(I+N) at the strongest base station receiver from the

user-selected mobile/remote unit at each route point and uses the ptc_data_rate.dat

file described above to determine the uplink data rate.


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