WIRELESS APPLICATIONS CORPORATION POWERSEARCH ONLINE (Version

Wireless Applications Corporation ________________________________________________________________________________________________

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WIRELESS APPLICATIONS CORPORATION POWERSEARCH ONLINE

(Version 4.0, part III)

Issue: October 30, 2002


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RF PROPAGATION POWER BUTTON TERMS

Terms Definitions AGL Above Ground Level; towers are measured from

ground level to their tip height. AMPS Advanced Mobile Phone System; It is the cellular

standard that was developed for use in North America. This type of system operates in the 800 MHz frequency band.

AMSL Above Mean Sea Level; Usually refers to terrain height with respect to sea level which is 0 ft.

Antennas are passive elements that transfer or convert energy from one form to another. The purpose of an antenna is to convert radio frequency electric current to electromagnetic waves, which are then radiated into space

Area Availability A statistical measurement of service quality level over entire cell coverage area under a specific traffic loading. The percentage of the service area covered all the time.

Azimuth is the direction or orientation based on either True North or Magnetic North (True North is used in our tools).

Base Station A piece of equipment used for communicating with mobile units. Depending on the context, the term Base Station may refer to a cell or a sector within a cell.

Beamwidth of an antenna is defined as the angle subtended between the two half- power (3 dB) points on either side of the main lobe of transmission. The half- power points are symmetrical around the radius containing the peak of the main lobe.

CDMA Code Division Multiple Access; It is an alternative digital standard developed in the United States.

Cell radius distance from the cell center to the effective cell coverage. It helps determine the number of cell sites required to initially cover an entire market.

Center Frequency The nominal frequency of a carrier wave. CF Correction Factor; A numerical value that is added

to the propagation model to adjust it to reality. This is determined by drive testing and integrating the results to the model. It fine-tunes the tool for things such as trees, buildings and residential areas.

Coordinates A pair of numbers that identifies a position relative to an axis. The Lat. and Long. are used to place the location on a map.

dBi Is the ratio (in dB) of the antenna gain to the isotropic or perfect antenna.


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dBm Is the ratio (in dB) of power to one milliwatt. Diversity The method of combining two or more received

signals to minimize the effects of path fading.

Diversity Gain An advantage to receive the signal during fading on the antenna receiving the better signal at that time.

Downlink Signal transmission from base station to mobile station, i.e. Forward Link.

Downtilt When the main lobe or beam of an antenna is intentionally adjusted below the horizon. There are two types – electrical and mechanical. Electrical downtilt is tuning the elements inside the antenna to aim down. Mechanical downtilt is physically adjusting the entire antenna to aim down.

EIRP Effective Isotropic Radiated Power; The transmitted power multiplied by the antenna gain relative to an isotropic (perfect) antenna.

ERP Effective Radiated Power; Energy-wise, this is the power that comes out of an antenna. This dictates the cell coverage area.

FAA Federal Aviation Administration; The organization responsible for the all the rules in airspace.

Fade Margin is the breathing space added to ensure signals are received at the required area availability.

FCC Federal Communications Commission; Responsible for the rules and regulations of frequencies.

Frequency The number of occurrences within a given time period (usually 1 second)

Ground Elevation (GE) The vertical distance from a datum, usually mean sea level, to a point or object on the earth's surface.

Hand-off The process of transferring the mobile station that has a call in progress on a particular channel to another voice channel without interrupting the call. This normally happens between Base Stations.

K Factor Ties in the relationship between the earth’s curvature and the atmospheric conditions that can bend the electromagnetic wave or frequency being used.

Latitude (Lat) A group of imaginary lines around the Earth parallel to the equator. The lines starts at 0 to 90 then back down with (-) numbers. They are split up in the N and S hemisphere.

Longitude (Long) A group of imaginary lines on the surface of the earth passing through the north and south poles at right angles to the equator. The lines starts at 0 to 180 then back down with (-) numbers. They are split up in the E and W hemisphere.

Morphology Characteristics, configuration and evolution of land areas

MOU Minutes of Use, a measure of wireless traffic


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NAD 27, 83 North American Datum 1927 and 1983 standards. NAD

27 is based on the survey the USGS did in 1927 and NAD 83 are the corrected surveys they did in 1983 (USGS 7.5” map coordinates are NAD 27 and the FAA requires NAD 83 coordinates).

PCN/PCS Personal Communications Network / Personal Communications Services

Receiver Sensitivity Is a measure of the receiver’s ability to receive weak signals. Usually expressed in dBm.

RF Radio Frequency; The electromagnetic frequencies in the range extending from below 3 KHz to 300 GHz, which includes radio and television transmission. These frequencies are above audio signals and below the frequencies of visible light.

RF Propagation is the transfer of radio-frequency energy through space by the broadcast of electromagnetic signals.

RX Receive, as in Receive antennas Signal Threshold The minimum intensity of a signal that can be

detected and recognized Traffic The measurement of messages or voice calls

transmitted on a communications system over a period of time.

TX Transmit, as in Transmit power Uplink Signal transmission from mobile station to base

station, i.e. Reverse Link. USGS United States Geological Survey – the people who

produce maps of the U.S.


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RF PROPAGATION THEORY

RF Propagation is the transmission of signals from a base station to space. It is generally represented by the coverage contour to show how far signals travel based on the site location, frequency and power.

Presented below is the main PowerSearch screen after you log in. Click the RF Propagation Power button.

To search a specific location, input the coordinates on the main map window before going inside the RF Propagation tool. Remember to select your coordinates as either NAD 27 or NAD 83. You can input up to two sites per session.


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Or use the Place a Site button to identify a location for Site A and/ or Site B.

Click the Return button to go back to the main map window.


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BASIC PROPAGATION When you click on the Basic Propagation button, this screen will pop up.

Identify the coordinates if they are NAD-27 or NAD-83 before inputting them (default is NAD-83). Input the coordinates if you did not do so in the main map

window or by using the Place a Site button. You can enter up to two sites per session.

Select the Frequency (Cellular or PCS).


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Determine the Antenna Type (Omni or Directional).

Put in the desired height of site.

Choose the Morphology of the area.

The default propagation model is Okumura.

Input desired signal threshold. Limit is from –30 to –150 dBm.

Name the azimuth and mechanical downtilt (if applicable) of the antenna.

Input the amount of power (ERP) you want the site to propagate. Limit is 0.1 to 1000 watts.


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You can always check on the site’s coverage by clicking on the box Click here to preview. PowerSearch will generate a thumbnail to show the site coverage when you do this.

Click on the Propagate button to run the coverage analysis of the site/s. Note that you can propagate two sites at the same time.

The tool will return you to the main PowerSearch map window after propagating your location(s) as shown below. This is the result of the Basic Propagation for these particular locations and its parameters.


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FULL PROPAGATION

When you click on the Full Propagation button, you are presented with the screen below. The Site Specs tab contains the physical attributes of the site. You will need to identify your center frequency, site coordinates, ground elevation and structure height in this section. You are also required to select the thresholds that will represent the propagated site.

Input the desired Center Frequency in MHz.

If you haven’t specify a location by inputting them on the main map window of

PowerSearch or by using the Place a Site button before going inside the RF Propagation tool, you can enter the coordinates of the site in the Site Specs tab. Make sure that you specify your coordinates as NAD-27 or NAD-83 prior to inputting them. Default is NAD-83. You can input up to two sites per session.


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Ground Elevation is defaulted to Terrain Data but you can override it in the User Input field. Also enter the proposed structure height.

Choose the number of Thresholds you want by clicking/ unclicking the check box, associate it with your choice of color and determine its levels in dBm. Signal threshold limit is –30 to –150 dBm.

You can always click on the Propagate button and the tool will propagate your location with the default antenna and parameters but it will close all windows and move you back to the main PowerSearch map window displaying your location and contour coverage. Return will move you back to the main PowerSearch screen.

Or you can click on Click here to preview to check your progress. Any field that you may have missed, the tool will use its default value. This will always display the lowest threshold selected for coverage.


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The Sector tab consist of the sector elements of the site. This section lets you choose your preferred antenna and calculate the effective radiated power (ERP) of the site. You can assign up to three sectors for each site.

Decide on how many sectors your site needs by clicking the appropriate check box. The Use Same Antenna button will select and allocate the same antenna selected in Sector 1 to Sector 2 and 3 if they are active. The Separate Evenly button will assign azimuths to each sector that are 120° out of phase with each other based on Sector 1’s azimuth.

The Select Ant. button gives you access to hundreds of antennas to choose from for your coverage design.

Click the Select Ant. button to choose an antenna.


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Select the Frequency and then the antenna type to start

Then choose the next query by either Make or MaxGain.


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The Other Filter field is just the other choice if you selected the other one. Click on Search to look for the antennas that qualifies to your query. Highlight the antenna of your choice and click on Use This Antenna to select that antenna and return to the main Sector tab. Clicking on the Details button will open another window that shows the antenna parameters.

The Azimuth is the orientation of the antenna with respect to True North. The Downtilt is the angle applied to the antenna with respect to the horizontal. Use the downtilt to concentrate the signal to a specific coverage objective. Enter your desired values in these fields.

Enter your desired ERP or click on Calc. ERP for a detailed power calculations.


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This is the detailed page if you want to compute for the ERP. You will need to identify your top and bottom jumper cables, main cable, connector losses and power outputs as well as the combiner loss and other losses that may be present in your system. Click Done to return to the main Sector page.

Enter the Centerline to complete the Sector tab. Remember to input the parameters of Sector 2 and 3 if they are active.


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The Parameter tab allows you to further enhance your coverage prediction by manipulating the Morphology class, Coverage Distance, Base Station and Mobile Station parameters and Fade Margin.

Click on Advanced to get to the detailed computation of the Fade Margin and to declare your values for Handoff, Traffic and Environment. These values will help the tool bring the coverage prediction more in tune with the real world.


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The Fade Margin Computation can be based on any of the three choices – Outdoor Only, In-Vehicle and In-Building. Confidence Interval is the percent probability that this amount of fading will happen in a given environment. Sigma is the summation of fading and mean is the average. In the current version of RF Propagation, we can only display the coverage in terms of contours. The Radial and Downlink features are under construction and this guide will be updated as soon as these new features are available. The Contour tab is shown next.

Select the Contour Type – First Break or Last Break, the Radial Spacing (default is 1 degree), Points of Smoothing (default is 9) and choose either Linear or Cubic Spline for Interpolation (default is Linear). You can also choose to shade the contours or not by checking the Contour Color Selections check box. Click the Propagate button to view the coverage based on contour. This will close all windows and move you back to the main PowerSearch map window displaying your location and its contour coverage. Cancel will return you to the main Power search screen.


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This is the result of the full propagation at this location with its given set of parameters.

FUTURE FEATURES Radial Propagation


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Downlink Propagation

The Save/ Load tab will save your site design and computations for future use and load it when evoked. Click on the Save Site A button to save site A and Save Site B button to save site B. A Save Successful window will appear after saving the site/s.


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Click on the ’Table A’ for Sector 1 2 3 button to view the Table A for the active sectors.

To load a saved site, just click the Name and confirm where you want it loaded in the new pop-up window. To remove a site, check the box on the left of the Name and hit Delete.


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ELEMENTS OF DESIGN SPECIFICATIONS 1. INTRODUCTION

The purpose of this document is to provide a simple procedure when using the RF Propagation tool in Power Search. This document covers both basic and full propagation site design. System implementation and the optimization procedures, rules and tactics are excluded.

2. DESIGN RULES AND STANDARDS 2.1 Frequency Criteria The tool can propagate sites at either AMPS or PCS frequencies, but not

limited to these technologies. Future versions will include other radio frequency bands depending on the need of the users.

2.1.1. Spectrum Allocation

AMPS SPECTRUM ALLOCATION

System Bandwidth

(MHz) Number of Channels

Base Station TX Freq. (MHz)

Base Station RX Freq. (MHz)

A 10 333 869.0 – 880.0 824.0 – 835.0 A’ 2.5 83 890.0 – 891.5 845.0 – 846.5 B 10 333 880.0 – 890.0 835.0 – 845.0 B’ 2.5 83 891.5 – 894.0 846.5 – 849.0

CDMA SPECTRUM ALLOCATION

System Bandwidth

(MHz) Number of Max Carriers

Base Station TX Freq. (MHz)

Base Station RX Freq. (MHz)

A 15 11 1930.0 - 1945.0 1850.0 – 1865.0 D 5 3 1945.0 - 1950.0 1865.0 – 1870.0 B 15 11 1950.0 - 1965.0 1870.0 – 1885.0 E 5 3 1965.0 - 1970.0 1885.0 – 1890.0 F 5 3 1970.0 - 1975.0 1890.0 – 1895.0 C 15 11 1975.0 - 1990.0 1895.0 – 1910.0

2.1.2. Center Frequency

Center frequency is the nominal frequency of a carrier wave. The default used in the basic propagation is:

Technology Center Frequency (MHz) Cellular (800 MHz) 870.0 PCS (1900 MHz) 1880.0

In full propagation, you can enter your preferred center frequency. Currently, it has a limit from 800 MHz to 1990 MHz.


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2.2. Coverage Criteria

Cell coverage can be predicted by coverage prediction models and is usually applied to a start-up system. The task is to cover the area with a minimum number of cell sites. The service area should be checked to determine what type of environment or morphology you have to design for. The results generated from the prediction model will differ every time a different morphology is used. These are true for contour, radial and downlink propagation.

2.2.1. Site Location

Site location is the targeted location to build a site. The reference datum can either be NAD 27 or NAD 83. You can place the coordinates by using the “Place It” button” before going into the RF Propagation tool or type in your desired coordinates.

2.2.2. Terrain Database

Terrain database is a digitized representation of the earth. It is essential to RF propagation as it affects the behavior of the radio waves. The RF propagation tool has its terrain database set to 3 arc second. The tool also allows the user to input the ground elevation of the proposed site if he chooses to.

2.2.3. Land Classifications The land classifications used are Large City, Small City, Suburban and Open Area. The following table defines the land classifications based on morphology. Each land classification will have varying propagation characteristics. These variations will determine the nominal cell radius to provide coverage. The following table will be used for the default determination of the land classifications for coverage planning:

Category Morphology Description

Large City Dense business districts with skyscrapers (10-20 stories and above) and high-rise apartments.

Small City Urban residential and office areas. Typical structures are 5-10 story buildings, hotels, hospitals, etc.

Suburban Mix of residential & business communities. Structures include 1-2 story houses 50 feet apart and 2-5 story shops & offices.

Open Area Open farm land, large open spaces and sparsely populated residential areas. Typical structures are 1-2 story houses, barns, etc.

2.2.4. Coverage Distance

Coverage distance is also known as the cell radius. RF propagation will calculate the signal level thresholds from the center of the site to the value specified in this field. The default value is 19 miles.


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2.2.5. Contour Type

Contour type is based on the first break or the last break. First break means that it will compute for the contour on the first time the signal dropped by the specified threshold. Last break occurs on the last time the signal went below the particular threshold.

2.2.6. Radial Spacing

Radial Spacing is the amount of separation between radials that it is going to compute for coverage predictions. The lower the value, the more detailed the computation.

2.2.7. Points of Smoothing

When it computes for the signal at the end point of the radial, point of smoothing is the average value to produce a smooth curve. The number on this field refers to the number of times the program will count when the signal drops below the signal threshold before averaging it.

2.2.8. Interpolation

Linear interpolation is a technique for approximating the value of a function between two known values based on the assumption that the three values lie on the same straight line

Cubic Splines are drafting aids used to draw smooth curves through a set of points. Weights are attached at the points to be connected and a flexible strip is shaped around the weights. Using this idea, we can create mathematical models of cubic spline.

2.3. Antenna Systems 2.3.1. Antenna Heights The antenna height is assigned a limit of 0 to 1000 ft. These assignments

will provide the basis for coverage and capacity analysis on a preliminary basis only. Zoning considerations and existing structure heights should be taken into consideration when designing sites. The typical antenna height parameters are as follows.

Location Antenna Centerline

Large City 60-100 ft (18-30 m) Small City 100-150 ft (30-46 m) Suburban 150-180 ft (46-55 m) Open Area 180-480 ft (55-76 m)


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2.3.2. Antenna Classifications

Antennas are transducers that transfer or convert energy from one form to another. The purpose of an antenna is to convert radio frequency electric current to electromagnetic waves, which are then radiated into space. The two primary classifications of antennas are omni and directional. In the basic propagation design, there are four default antennas used to run propagation. It is necessary to use appropriate default antenna types to undertake the initial planning. The default antennas defined by WAC are as follows. Antenna Type

Antenna Model

Frequency Horizontal Beamwidth (Deg.)

Vertical Beamwidth (Deg.)

Gain (dBi)

Omni SRL488 Cellular (800 MHz)

360 4.5 12.1

Directional DB872H3-XC Cellular (800 MHz)

83 29 11.5

Omni AO1909 PCS (1900 MHz)

360 6.5 11.1

Directional SP - 9014 PCS (1900 MHz)

84 - 88 7 - 9 16.1

As for the full propagation design, you can choose from a list of different antenna models in the sector tab. There will be cases that will require other models of antennas not in the list, and based on the RF analysis, the appropriate antennas will be added.

2.4. Modeling Criteria

With the increase in the number of cell sites, the need to theoretically predict the actual path loss experienced in the system is becoming more and more crucial. As cellular communication systems mature, a growing reliance is placed on the propagation tools. The propagation model used by the operator is directly involved with the capital build program of the company. Therefore, it is essential that the propagation model tool to be understood. It should be understood in terms of what it can and cannot predict. Presently, most available cellular propagation tools utilize a variation of the Hata model. The PCS and some cellular operators are using a variant of the Cost 231 model. Through understanding their advantages and disadvantages, a better engineering design can take place in a network.

2.4.1. Models used

Okumura Okumura et al carried out a detailed analysis for path predictions around Tokyo for mobile terminals. The Okumura report is a series of charts that are instrumental in radio communication modeling.


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Hata Hata model is an empirical formula based on Okumura’s results to predict path loss so they can be used in a computational model. Walfish – Ikegami The Walfish – Ikegami propagation model is used for estimating the path loss in an urban environment for cellular communication. This is a combination of empirical and deterministic modeling used over the frequency range of 800 to 2000 MHz. Cost-231 – Hata This is a variant of the Hata model for urban environment. The Cost 231 model is composed of three basic components: 1. Free space loss 2. Roof to street diffraction loss and scatter loss 3. Multiscreen loss

2.4.2. Model Optimization

The correction factor (CF) has a default value of 0 for both slope and intercept in basic and full propagation mode. The user can only adjust these values to further optimize the propagation model in the full propagation mode. The above values need to be referenced to frequency, path loss, transmit antenna height and receive antenna height.

2.4.3. Signal Level Thresholds and Colors

The signal level thresholds should be derived using a link budget analysis prior to your design. However, arbitrary values can be used to represent these thresholds. It has a –30 to –150 dBm limit. The RF propagation tool of Power Search has four levels of threshold that the user can specify and associate with different colors.


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References

1. Cellular System Design and Optimization by Clint Smith, P.E. and Curt

Gervelis, McGraw–Hill, 1996

2. ARRL Antenna Handbook, 1997 Edition page 2-1

3. Mobile Cellular Telecommunications Second Edition by William C.Y. Lee, McGraw–Hill, 1995

4. Radio System Design For Telecommunications Second Edition by Roger L.

Freeman, Wiley-Interscience Publications, 1997

5. RFPlan Wireless Modeling Tool Instruction Manual by Nucomm Inc., 1999

6. Wireless Communications - Principles & Practice by Theodore S. Rappaport, IEEE Press, 1996.

7. Celwave Product Section Guide v1.2 by Radio Frequency Systems Inc., 1999

8. OneLook Dictionaries at www.onelook.com

9. FAQ at www.softwright.com

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WIRELESS APPLICATIONS CORPORATION POWERSEARCH ONLINE (Version