step by step e7495a b users guide

E7495A/B, Option 210 Over-Air Base Station Test Step-by-Step User’s Guide

Agilent E7495A/B Opt 210 Over-the-Air Base Station Test Set Step by Step Measurement Guide

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What You’ll Find in this Document

Topic Page

Configuring the E7495A/B Over-Air Measurements 4

Determining Over-Air Measurement Validity 8

Evaluating the Over-Air Code Domain Power (CDP) Measurement 11

Evaluating the Over-the-Air Code Domain Power Measurement 17

Evaluating the Code Domain Power and Traffic Metrics 21

Comparing Traffic Metrics for Multicarrier Sites 24

Appendix 1 – Setting Over-the-Air Measurement Properties 25

Appendix 2 – Setting the Amplifier Capacity Properties 26

Appendix 3 - Effects of Interference on Estimated Rho 27


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Configuring the E7495A/B Over-Air Measurements

Steps Notes 1. Power up the Agilent E7495A/B Base

Station Test Set by pressing the On/Off key once. Using the On/Off Control: • Sleep Mode – to put the test set

into sleep mode: Press and release the on/off key and the test set state will be saved and the unit will enter sleep mode.

• Power off – to power off the test set: Hold the On/Off key down until the Green indicator light goes out, approximately eight seconds.

2. Connect the GPS antenna to the GPS Antenna port and the RF Antenna to the band-specific preselector filter. Connect the filter and antenna assembly to the RF IN Port 2.

3. Position the GPS antenna in a location with an unobstructed view of the sky

When you use two E7495A/B test sets, keep the active (5V) GPS antennas a minimum of three feet apart to help eliminate cross talk between the antennas. The RF antenna does not cause interference. If you are at the base station, verify that the E7495A/B GPS antenna is not located near the active BTS GPS antenna.

ON/OFF


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Steps Notes 4. Press the Mode button. Then press the

[Over Air] softkey, followed by the [CDMA Over Air] softkey. The CDMA Over Air measurement screen loads.

5. Check that the [Units] softkey is highlighting Chan. If required, press the [Units] softkey to select Chan.

6. Press the [Channel] softkey, and enter the correct channel number using the numeric keypad. Then press the [Fwd] softkey to select the forward RF direction to test.

The E7495A/B Over-the-Air tool does not measure the reverse link (mobile’s uplink).


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Steps Notes 7. With the GPS antenna connected, the

GPS status indicator in the bottom left corner of the display should say “GPS Locked.” If the indicator shows “GPS Unlocked,” adjust the GPS antenna to have a clear view of the sky.

8. Check that the[ Fr/Time Ref] softkey shows GPS. If required, select GPS using the [Fr/Time Ref] softkey.

9. Verify that the Fr/Time Ref indicator on the bottom right corner of the display shows GPS and displays a green circle.

Satellite Lock


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Steps Notes 10. To view the GPS timing status, press

the [Level/Location] softkey on the left side of the display, to select GPS Location On. The GPS status is displayed with the latitude, longitude, altitude, current date and time, along with the current number of satellites tracked. When you find an optimum measurement location, record the coordinates. Later, when you make a measurement in a particular sector, you can use the coordinates to verify that you are measuring from the same general location.


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Determining Over-Air Measurement Validity

Steps Notes 1. Find a valid measurement location in

the main beam of each sector.

The proper measurement location for over-air testing is based on high pilot dominance and low multipath energy. To make over-air measurements, locate the test set at least 100 yards back from the cell tower, centered in the main beam of the antenna. If the test set is located at the tower, it may be under the signal in a high-energy area associated with the back beam of the other sectors.

2. Verify that the PN Offset that is displayed is the PN of the sector you want to test. Press the [PN Offset] softkey to select Manual, then enter the correct PN for the sector of interest. This will lock the metrics for the site to the PN of interest.

The PN Offset for a site can be found automatically, but the best way to evaluate a sector is to manually enter a PN, and then monitor the site metrics over a period of time. If another PN temporarily gains dominance, then the metrics will be grayed out but not reset in manual mode. Each sector of a cdma base station has a PN which identifies the site or sector to mobiles in the area.

Ideal Measurement Location Main

Beam


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Steps Notes Since all the sectors of the base station transmit on the same RF channel, you will need to check the PN to make sure you are measuring the correct sector. If the PN offset on the metrics display does not match the PN offset of the sector you want to test, you may be measuring the wrong sector. Move your receiving antenna to a different location to see if you can find the desired PN offset. If you have moved all around the base station and have found a different PN offset for each sector, but none of the numbers correspond to the PN offset you want to test, one of the following problems may exist: • This Base Station does not have a sector

assigned with the PN offset you want to test. • The PN Inc field in the measurement controls is

set to an increment that is not correct for your system. If in doubt, set the increment to 1. Press the [Freq/Channel/Time Ref] softkey, then select PN Inc.

• The GPS receiver in the base station is not working correctly, and the base station timing is incorrect.

• The E7495A/B GPS receiver is not locked to the GPS satellites. Verify that the GPS status field on the bottom left of the display indicates GPS Locked.

• 3. Check that Pilot Dominance and

Multipath Power parameters meet the minimum requirements. You may need to change measurement locations to achieve the necessary signal levels.

In order to make valid measurements in an over-the-air environment, it is necessary to get a sufficiently strong cdma signal from the base station you are measuring. Cdma over-the-air measurements will experience interference from other cdma signals on the same RF channel and from multipath echoes. The code domain power view measures two key parameters to monitor these effects: • Pilot Dominance – The difference

in amplitude of the strongest pilot channel and the second and third strongest pilot channels (expressed in dB). Ideally, this value will be very large (> 16 dB), but will meet minimum requirements at > 10 dB.


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Steps Notes • Multipath Power – The amount of power, of

the dominant pilot signal, that is dispersed outside the main correlation peak due to multipath echoes (expressed in dB). Ideally, this value will be very small (< 0.1 dB) but will meet minimum requirements at < 0.4 dB.

The table below shows the quality of the over-the-air code domain measurements with respect to pilot dominance and multipath power.

Measurement Quality

Pilot Dominance

Multipath Power

Very good > 16 dB < 0.1 dB

Fair > 10 dB < 0.4 dB

Marginal > 8 dB < 0.7 dB

The default measurement properties for Pilot Dominance and Multipath Power are set to give fair measurement quality. When the pilot dominance and multipath power are within the limits to yield fair measurement quality, the values are shown in green. When the pilot dominance and multipath parameters are outside the acceptable limits, the parameters turn red. For a description on how to set the default measurement properties, see Appendix 1 – Setting Over-the-Air Measurement Properties on page 25.

4. Move the RF antenna position/location or use a directional antenna to achieve the following:

• Multipath Power < 0.4 dB (Ideally < 0.1 dB)

• Pilot Dominance > 10 dB (Ideally > 16 dB)

If you haven’t changed the default measurement properties for pilot dominance and multipath power, these parameters will turn from green to red when multipath power is > 0.4 dB and pilot dominance is < 10 dB. The other RF parameters will be grayed out. You can view pilot dominance for the top three pilots displayed. Pilot dominance is the difference between the strongest pilot and the second and third strongest pilots.

5. If you are unable to achieve good pilot dominance and multipath power, you can change their default measurement properties. Note: This may reduce the quality of your measurement and result in invalid measurement results.

See Appendix 1 – Setting Over-the-Air Measurement Properties on page 25 to learn how to set the pilot dominance and multipath power properties.


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Evaluating the Over-Air Code Domain Power (CDP) Measurement

Steps Notes 1. Observe the CDP Trace.

The CDP (Code Domain Power) trace shows the code channels that are present in the cdma 1.23 MHz RF channel. These channels can be cdma control channels or traffic channels. The vertical axis is the level of the channel in dB relative to the total channel power. The horizontal axis shows the channel number. As you will notice, the channel numbers are not arranged sequentially 1-128. They are arranged in what is called Bit Reverse order. This ordering is necessary to show the channelization of the supplemental channels associated with high data rate cdma2000 channels. The red horizontal line on the display is called the threshold line. Channels above this line are considered to be active, and signals below the line are noise. Active channels are shown as colored bars. The noise is shown as light gray.


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Steps Notes 2. Verify that the Pilot, Paging, and Sync

control channels are present on the CDP Trace.

The Pilot Channel is colored red and is Walsh channel number 0. There is only one pilot channel per carrier. This is probably the most important cdma control channel. The pilot channel is used as a coherent phase reference by all mobiles on this RF channel and PN. It also provides a means for mobiles to identify one cell from another. The Sync Channel is colored dark blue and is Walsh channel number 32. The sync channel transmits time of day information. This allows the mobile and the base to align clocks which forms the basis for decoding all the Walsh codes. The Paging Channel is green and is generally Walsh channel 1. It is the digital control channel for the forward link. The mobiles respond to control information on this channel. A single cdma RF channel can have multiple paging channels. If any of this control channels are not present, the base station may not be able to carry traffic. For example, if the paging and sync channels are not present, a base station may be able to accept a traffic channel hand off from another base station, but will not be able to originate calls. This is a particularly hard problem to find without using the CDP trace display on the over-the-air test set because base station switch metrics may show that the base station is carrying traffic, but users close to the base station will not be able to originate calls.

Pilot Sync Paging


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Steps Notes Note: The sync and the paging channels are in

different locations when compared to older IS-95 only code domain trace screens. This is because of the bit reverse ordering of the CDP trace to show the cdma2000 data channels. In reality, the paging and sync are still the same Walsh code number. The bit reverse order makes it appear that the channels are in different locations. In some multicarrier configurations, the paging and sync channels may not be present. Contact your RF engineering department for further information.

3. If you are testing a cdma2000 BTS and the Quick Page Channel is enabled on the network, verify that it is present on the CDP Trace. To turn on the Quick Page functionality on the E7495A/B, press the [Setup] softkey, to set the Quick Page Channel to Chan 80.

With the advent of cdma2000, a new control channel called the Quick Page Channel has been added. The quick page channel is used to improve standby time in the mobile. The quick page channel may or may not be enabled. On the CDP trace, the quick page channel is colored light blue and is generally channel number 80. It is possible to have quick page channels at channel 80, 48, and 112. It is important to point out that the quick page channel is a bursted channel. In other words, it is not on all the time. You may have to wait to see the quick page show up on the trace. The quick page parameter on the metrics display can help you determine the level of the quick page channel. Note: The quick page channel is a one-wide

Quick Page


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Steps Notes channel; in other words, it only occupies one of the 128 channels. The pilot and sync control channels are also single wide Walsh code channels. The paging channel is two wide, occupying two of the 128-length Walsh code channels.

4. Observe the traffic channels on the CDP Trace.

There are two types of traffic channels that are displayed on the CDP Trace: IS-95 traffic channels and cdma2000 traffic channels. Walsh codes identified as IS-95 channels are colored yellow. IS-95 channels are always two wide (Walsh length 64) channels out of the 128 Walsh codes on the CDP trace. Walsh codes identified as cdma2000 are colored orange and can represent either voice or data. The channel width can vary from a one wide (Walsh length 128) to a 32 wide channel. As the data rate of the cdma2000 channel increases, the width of the channel increases proportionally. Any active channel that cannot be identified because of low signal levels is colored a light tan. Generally, these channels are some type of voice traffic channel, but because the level is too close to the noise floor, the test set cannot determine absolutely the type of call. When you see a tan channel present, you know there is energy in that Walsh code. With experience, you will begin to make an educated guess as to the type of channel.

IS-95 cdma2000


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Steps Notes 5. Observe the noise floor on the CDP

Trace.

The light gray bars on the CDP trace display are noise. While they appear to be channels on the trace and are referred to as noise channels, they are not real cdma channels. They represent the noise energy in the Walsh code. The average level of the top of these noise bars represents the CDP Trace noise floor. The noise floor level can be influenced by many conditions. The existence of high power from another cdma base station or the distance from the base station you are measuring can affect the noise floor. It is desirable to reduce the noise floor as much as possible before making measurements. Locating the measurement antenna as close as possible to the center of the lobe of base station antenna can help to reduce the noise floor. Finding a location that results in a -30 dB noise floor would be considered good. If you have a strong signal with low multipath power and high pilot dominance parameters on the metrics display, but still show a high noise floor, then a problem may exist in the base station.

6. Determine if a problem exists. At first it may be hard for you determine if problems exist in the RF. However, with experience you will begin to recognize problems with the base station just by viewing the CDP Trace. Below are a few examples of problems that can be identified with the CDP Trace display.

Noise Floor


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Steps Notes Channel elements remain on with no actual traffic on the site.

Missing Sync Channel


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Evaluating the Over-the-Air Code Domain Power Measurement

Steps Notes 1. On the Over-the-Air Metrics display,

verify that the PN being measured is the PN Offset of the sector you want to test. Set the PN Offset softkey to Manual.

Each sector of a cdma base station has an assigned PN. The PN identifies the cell site or sector to mobiles operating in the network. Since all the sectors of the base station transmit on the same RF channel, you will need to check the PN to make sure you are measuring the correct sector.

2. Verify that the Time Offset value is within the following limits: • < ± 10 µsec if the receiving

antenna is next to the base station antenna.

Or • < ± 10 µsec + 1µsec for ever 900 ft

you are distant from the base station antenna.

The time offset measures the time the pilot signal arrives from the base station with respect to GPS time. It is expressed in microseconds (1 µsec is the time it takes for a signal to travel about 900 ft). Time offset, or delay, is a combination of propagation delay and base station timing error. IS-95 specifies that the base station timing must be within ± 10 µsec of its assigned value. Many base station manufacturers specify that the timing must be within ± 3 µsec. For example, if you are parked near the transmit antenna, the propagation delay is approximately 0. The measured value of delay should be within the recommended limits, which is greater than – 10 µsec and less than + 10 µsec. As you move away from the transmit antenna, propagation delay needs to be considered – about 1 µsec for every 900 feet. If you are parked ½ mile from the transmit antenna, the additional propagation delay would be approximately 3 µsec. The measured value of delay should be greater than – 7 µsec and less than + 13 µsec. If the measured value of delay falls outside of the expected range, consider the following problems: • The GPS receiver in the base station is not


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Steps Notes working correctly, and the base station timing is incorrect.

• The base station main oscillator is not working correctly, and the base station timing is incorrect.

• The E7495A/B GPS receiver is not locked to the GPS satellites. Verify that the GPS indicator shows GPS Locked.

3. Verify that the Est Rho (Estimated

Rho) meets the following criteria: > 0.8 if the multipath power and pilot dominance properties remain at the defaults of 0.4 dB and 10 dB, respectively.

Or

> 0.912 if you have set the multipath power and pilot dominance properties to 0.1 dB and 15 dB, respectively.

Estimated Rho is the measure of the modulation quality for a cdma transmitter. This is analogous to measuring FM accuracy and distortion in an AMPS network, or EVM in a TDMA system. Rho is unit less. A Rho value of 1.0 is perfect, indicating that all of the power is being transmitted correctly. The cdma standard specifies that Rho must be greater than 0.912. Typical values for a healthy base station are greater than 0.94. When measuring Rho over the air, these values can only be achieved under very good conditions with very little multipath power and very high pilot dominance. For example, a multipath power of < 0.1 dB and a pilot dominance of > 15 dB is required to measure Rho of 0.912. Refer to Appendix 3 - Effects of Interference on Estimated Rho on page 27 for more on the effects of pilot dominance and multipath power on estimated Rho. Poor Rho performance affects the base station capacity because the uncorrelated power appears as interference to the mobiles. The added interference requires an increase in the traffic channel level to overcome the interference. This may, in turn, be seen as cdma signal. Use the spectrum analyzer to verify that no spurious signals are present in the band of the transmitter. Compression may be occurring in the base station power amplifier. There may be errors in the base station IQ modulator.

4. Verify that the Carr Feedthru (carrier feedthrough) is < -20 dB.

Cdma base stations use QPSK modulation. QPSK is a suppressed carrier modulation meaning that a perfectly modulated signal has no power at the exact carrier frequency. Carrier Feedthrough is a measure of how much power is at the center frequency. Carrier Feedthrough is expressed in dB relative to the channel power. The measured value for Carrier Feedthrough should be less than –20 dB


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Steps Notes (preferably less than –25 dB). High levels of carrier feedthrough may indicate excessive DC offsets in the base station’s IQ modulator.

5. If you have previously measured the Pilot Pwr on this sector and carrier of the base station, verify that the Pilot Pwr reads within ± 3 dB of previous values, when measured from the same location using the same measurement antenna.

Pilot power is the total power in the dominant pilot signal, expressed in dBm. The transmit power of the pilot channel signal for a given base station is constant. When measured over the air, pilot power will vary somewhat due to varying propagation conditions and environmental conditions. If the power has varied significantly from previous readings at the same location, it may indicate the following: 1. There has been a change made to the digital

gain setting of the pilot channel. 2. The base station power amplifier has a

problem. 3. The transmit antenna system has been changed

or damaged.

4. Verify that the ∆ Page Pwr is < ±0.5 dB from the intended setting for your system.

Delta paging power is the amplitude difference between the paging channel and pilot channel, expressed in dB. The transmit power of the paging channel is constant and can be set at a value relative to the pilot channel power. A common value is –4 dB relative to the pilot. It is important to know what the intended settings are for each carrier and sector of your base station. If the measured value of ∆ Page Pwr is more than ±0.5 dB different from the intended setting, it may indicate that the digital gain setting for the paging channel has been changed.

7. Verify that the ∆ Sync Pwr is < ± 0.5 dB from the intended setting for your system.

∆ Sync is the amplitude difference between the sync channel and pilot channel, expressed in dB. The transmit power of the sync channel is constant and may be set at a value relative to the pilot channel power. A common value is –10 dB relative to the pilot. It is important to know what the intended settings are for each carrier and sector of your base station. If the measured value of ∆ sync is more than ± 0.5 dB different from the intended setting, it may indicate that the digital gain setting for the Sync Channel has been changed.


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Steps Notes 8. If you are testing a cdma2000 BTS and

the Quick Page Channel is enabled, verify that the ∆ QPCH PK Pwr is < ± 0.5 dB from the intended setting for your system. Note: You must turn on the Quick Paging channel measurement using the [Setup] softkey. The default setting is Off.

∆ Quick Page peak power is the amplitude difference between the Quick Page channel and pilot channel, expressed in dB. The quick page channel is a bursted channel and is not on all the time. In order to capture the level of the quick page channel, the statistic measures and holds the peak level of the quick page channel. Until a quick page channel has been measured, the value will be dashes. The level of the quick page channel, when on, is constant and is set at a value relative to the pilot channel power. The quick page digital gain level can be set to 2, 1, 0, -1, -2, -3, -4, and –5 dB relative to the pilot. It is important to know what the intended settings are for each carrier and sector of your base station. If the measured value of ∆ QPCH PK Pwr is more than ± 0.5 dB different from the intended setting, it may indicate that the digital gain setting for the Quick Page Channel has been changed.


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Evaluating the Code Domain Power and Traffic Metrics

Steps Notes 1. If not already done, turn on and set the

four Amplifier Capacity Properties on the [Reset/Amp Cap] softkey.

Appendix 2 – Setting the Amplifier Capacity Properties on page 26 describes how to set the two amplifier properties. WARNING A base station power amplifier is specified to have a maximum power limit. Above this limit, the amplifier generally functions, but distortion of the cdma waveform may be present and damage to the amplifier is possible. Depending on system requirements, each base station can be outfitted with power amplifiers capable of different maximum output power levels. Therefore, it is necessary to configure the amplifier capacity parameters to match the power amplifier of the base station you are testing. If the power amplifier parameters are not configured correctly, the three capacity parameters (Amplifier Overall Capacity, Peak Amplifier Capacity and Average Amplifier Capacity – all expressed in percent) will be invalid.

2. Monitor the metrics for at least 10 minutes.

This monitoring is best done during high cell site utilization periods.

3. View the Amp Cap percentage measurement field.

The Amp Cap measurement is an estimate of the amount of amplifier power capacity that is being used, expressed in percent of the maximum. When an amplifier is transmitting at maximum output power, it is said to be at 100% of its capacity. For example, an amplifier with a maximum output power of 12 watts would be at 50% of capacity when transmitting 6 watts and at 100% of capacity when transmitting at 12 watts. The percentage of amplifier capacity increases as the number or level of the traffic channels increases.

4. View the Utilization measurement. Utilization is a ratio of the active Walsh codes to the total 128 Walsh codes, expressed in percent. Even


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Steps Notes though active control channels such as the pilot are included in the utilization measurement, utilization is an indication of the traffic that is being carried by the base station. For example, a cdma signal with pilot, paging, and sync channels, two IS-95 traffic channels, and one eight wide cdma2000 data channel, would use 18 Walsh codes. Each control channel would use two Walsh codes, each IS-95 channel would use two Walsh codes, and the cdma2000 channel would use 8 Walsh codes for a total of 18 Walsh codes. Eighteen Walsh codes in use out of the 128 total Walsh codes results in a utilization of 14%.

5. To save the measurement data on the Over-the-Air screen: • Insert a PC card, if one is not

already present. • Press the Save Data button. • When the Save Data screen

appears, name the report using the knob to select letters.

• Press the [Ok] softkey to generate an Excel compatible csv file on the PC card.

The screen capture is saved as a PNG format graphic file that can be opened with a graphics tool.

6. To save a screen capture, press the Print Screen button.

7. Verify that the Pk Amp Cap (Peak Amplifier Capacity) is < 100 %.

Pk Amp Cap is the peak level of all the valid Amp Cap measurements while on the same PN offset. This measurement is reset if the PN offset changes and in Auto PN if the metrics are reset. WARNING: If the Pk Amp Cap is greater than 100 %, the traffic at this base station has caused the base station amplifier to exceede its maximum power rating. This is not desirable, and you should contact your RF engineering department as soon as possible. This problem can result in system degradation or damage to the amplifier. You can get an indication of how often the amplifier capacity is being exceeded by watching the Amp Cap measurement. This is an instantaneous measurement of the amplifier capacity.

8. Verify that the Avg Amp Cap (Average Amplifier Capacity) is

Avg Amp Cap is the average level of all the valid Amp Cap measurements while on the same PN


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Steps Notes < 85 %. offset. The measurement will be reset if the PN

offset changes while PN Offset is set to Auto. Note: To manually reset the Avg Amp Cap press the [Reset/Amp Cap] softkey, then press the [Reset Metrics] softkey. WARNING: If the Avg Amp Cap value is greater than 85%, the base station power amplifier is close to its maximum power limit. Further increase in traffic on this base station could cause system performance problems or damage to the power amplifier. You should notify your RF Engineering Department as soon as possible.

9. Verify that the Pk Util (Peak Utilization) is < 65 %.

Pk Util is the peak level of all the valid utilization measurements while on the same PN offset. This measurement is reset if the PN offset changes while PN Offset is set to Auto. If the Pk Util of this base station is greater than 65%, this is a warning that peak traffic rates at this base station are getting very high. It is possible that calls could be getting blocked or dropped. You should contact RF engineering as soon as possible.

10. Verify that the Avg Util (Average Utilization) is < 45 %.

Avg Util is the average level of all the valid utilization measurements while on the same PN offset. This measurement is reset if the PN offset changes while PN Offset is set to Auto. The base station is carrying a great deal of traffic if the Avg Util of this base station is greater than 45%. It may be time to consider adding another carrier or another base station. You should contact RF engineering.

11. Verify that the Avg Amp Cap is < 75 % and the Avg Util is < 12.5 %.

It is not desirable for a base station to use up a lot of the amplifier capacity (Avg Amp Cap) with a low volume of traffic (Avg Util). This condition indicates that a significant amount of RF amplifier capacity is being allocated to a low number of mobile units. This may indicate the following: • The mobiles being served are a long distance

away. • The mobiles may be inside a building or behind

an object that is attenuating the RF signal from the mobiles.

You should report this condition to RF engineering.


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Comparing Traffic Metrics for Multicarrier Sites

Perform the following if you are testing a multicarrier base station and you have completed all the previous steps for each carrier.

Steps Notes 1. Open all saved metrics reports for each

carrier on the same sector of the base station.

The saved data reports should be on the PC card and can be opened with Excel.

2. Compare the Avg Util (Average Utilization) of all carriers. The Avg Util Cap should not vary greatly between the carriers of one sector on a base station.

Typically, it is desirable to balance the amount of traffic on each carrier. If the average utilization is significantly different between the carriers, it could indicate the following: • There could be a hardware problem with one

of the carriers of the base station, such as a bad power amplifier or channel card.

• There could be a problem with the base station software settings for this sector.

• The carriers are being used for different types of traffic. For example, one carrier may only be used for voice calls and the other for data calls.

You should consult with RF engineering to determine if there is a problem.

3. Compare the Avg Amp Cap (Average Amplifier Capacity) of all carriers. If the Avg Util is similar between carriers, the Avg Amp Cap should not vary greatly between the carriers of one sector on a base station.

Generally, if the traffic is balanced between carriers as indicated by Avg Util, the Average Amplifier Capacity should be balanced between carriers. This should be true if the carriers all share the same amplifier or use amplifiers with the same maximum power limits. If the Avg Util is balanced and the carriers share the same amplifier or same type of amplifier, and the Avg Amp Cap is substantially different between carriers, this could indicate the following: • One of the power amplifiers for a carrier is

not performing properly. • The duplexer or filter for a carrier is not flat

across the band. • The antenna or feedline has a problem.

4. Repeat the above steps for each sector of the base station as each sector operates independently, and good performance on one sector does not guarantee good performance on all sectors.


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Appendix 1 – Setting Over-the-Air Measurement Properties

Steps Notes 1. To change the measurement validation

parameters: • Press the [Setup] softkey. • Select either the [Plt Dom] or

[Mp Pwr] softkey. • Enter a new value.

The measurements parameters are displayed along the right side of the display. Press the appropriate softkey, and then enter a new value for the parameter with the numeric keypad.

2. To change the Over-the-Air Code Domain Power from Relative to Absolute: • Press the [Level/Location] softkey. • Press the [Reference] softkey to

select the appropriate setting.

Relative power levels display the power in the Code Domain in relation to Channel power. Absolute power displays the power in each code channel in terms of absolute power levels.


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Appendix 2 – Setting the Amplifier Capacity Properties

A cdma base station is typically set up with a specified amount of power, allocated to the pilot channel. Power settings specified for the paging and sync channels are defined relative to the pilot channel. Occasionally, the paging and sync channels’ power settings are also specified in absolute power units (watts). Given the pilot, paging, and sync power setup values and the maximum power output of the amplifier, the percentage amplifier capacity setup parameters can be determined. Key properties that must be set correctly in order to report valid Amp Cap Metrics in the CDMA Over Air screen. • Pilot Pwr of <value>: (the default value = 1.5 W). Enter the absolute power value in dBm or

Watts for the pilot channel in a no-traffic state. • Max PA Pwr of <value>: (the default value = 15 W). Enter the maximum power amplifier

power for the sector under. This would be the single carrier power level. • ∆ Page Pwr of <value>: (the default value = -4 dB). Enter the standard value used across

your network. • ∆ Sync Pwr of <value>: (the default value = -9 dB). Enter the standard value used across

your network.

Steps Notes 1. To change the Amplifier Capacity

parameters: • Press the [Reset/Amp Cap]

softkey. • Select the parameter from the

softkeys on the right side of the display.

Amplifier capacity parameter values are displayed on the right side of the display.

2. Press the appropriate softkey, and then enter a new value with the numeric keypad.


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Appendix 3 - Effects of Interference on Estimated Rho

Estimated Rho is a measure of cdma waveform quality and is typically made at the transmitter output. In an over-the-air scenario, the system measures the waveform quality of the received signal that has been subjected to the effects of interference and multipath. As interference and multipath raise the noise floor of the code domain power measurement, the maximum expected reading of estimated Rho decreases. As pilot dominance decreases and/or multipath power increases, the maximum reading you should expect from estimated Rho decreases. Table 1 below shows the degradation of estimated Rho expected for various values of pilot dominance. This table assumes the ratio of the traffic power received from the two sectors (strongest and second strongest) is approximately the same as the ratio of the pilots (pilot dominance). If the traffic power from the sector with the strongest pilot is much higher, the degradation will be slightly less. If the traffic power from the second sector is much higher, the degradation will be slightly more. Table 1. Estimated Rho degradation due to Pilot Dominance.

Pilot Dominance Est Rho Degradation (X)

5 dB 0.25

6 dB 0.21

7 dB 0.17

8 dB 0.14

9 dB 0.12

10 dB 0.10

11 dB 0.08

12 dB 0.06

13 dB 0.05

14 dB 0.04

15 dB 0.03

16 dB 0.025

17 dB 0.02


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Table 2. Estimated Rho degradation due to Multipath Power.

Multipath Power Est Rho Degradation (Y)

0.75 dB 0.17

0.70 dB 0.16

0.65 dB 0.15

0.60 dB 0.14

0.55 dB 0.135

0.50 dB 0.13

0.45 dB 0.12

0.40 dB 0.10

0.35 dB 0.09

0.30 dB 0.08

0.25 dB 0.06

0.20 dB 0.05

0.15 dB 0.04

0.10 dB 0.03 When measuring estimated Rho over-the-air, the degradation due to an interfering sector and multipath echoes must be considered when interpreting the results. The maximum estimated Rho you should expect to measure is calculated as:

Maximum estimated Rho = 1.0 - X - Y Where, X is the degradation due to pilot dominance as shown in Table 1, and Y is the degradation due to multipath echoes - see Table 2. Sample calculation: Pilot dominance = 14 dB ≥ X = 0.04 Multipath power = 0.4 dB ≥ Y = 0.10 Maximum estimated Rho = 1.0 - 0.06 - 0.10 = 0.84 In this case, measurements of estimated Rho substantially less than 0.84 indicate poor waveform quality from the sector under test, or possible interference from outside of the cdma system.

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