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Reconfiguration Implementation Phase:
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Reconfiguration Implementation Phase Overview
4. Complete Pre-Reconfiguration Prep Work
Concurrent with Sprint Nextel clearing frequencies, complete any tasks that can be performed in advance of physical reconfiguration. The specific activities included in this step will vary significantly depending on the complexity of your system. Prep work may include facility preparation, retuning subscriber equipment, system baseline testing (if required), or other activities outlined in your reconfiguration plan.
5. Reconfigure Infrastructure and Subscriber Equipment
Activities that may occur during actual infrastructure reconfiguration include site retunes, subscriber equipment retunes, and other tasks necessary to operate on the new frequencies while minimizing disruption to the existing operations. Again, specific activities completed as part of this step will vary depending on the complexity of your system.
During the course of your reconfiguration, Sprint Nextel will remit payments either to you or directly to your vendor(s) in accordance with the arrangements and schedule in your Frequency Reconfiguration Agreement. More information is available in the Payment Process and Funding Guidelines sections of this Handbook.
6. System Cutover
The system cutover milestone is reached when all reconfiguration tasks are complete. At this point all infrastructure and subscriber equipment is verified to be operational on the new frequencies.
7. Complete Acceptance Testing (if required)
If required, acceptance testing ensures the reconfigured system is comparable to the pre-reconfiguration system parameters.
In certain circumstances, larger public safety and CII systems may seek to conclude the retuning process with a formal acceptance test of the system to validate operations on the new frequencies (validation of the retuning process for most conventional systems, by contrast, should be a simple exercise). Such a test would serve as the primary basis for certifying completion of your reconfiguration; you and/or your vendor would develop a structured test plan and schedule, with acceptance criteria that your personnel would validate have been met at each step in the test. It is expected that the scope of such a test would vary considerably depending upon the size and complexity of the system. Interoperability across agencies and Mutual Aid functions should also be built into the test where appropriate.
If you and Sprint Nextel agree on an acceptance test of your system, it must be included in the agreed upon Cost Estimate (and SOW for complex systems) that will be part of your Frequency Reconfiguration Agreement. The scope, level of effort and cost of the test must be specified and agreed to during FRA negotiations.
For some systems, testing to validate coverage may also be necessary. The following describes TA guidelines for three methods for testing, and provides descriptions of when the use of each method may be appropriate. The guidelines are designed to allow licensees flexibility, but to provide guidelines that must be considered when a licensee is determining if testing is necessary and, if so, what level is appropriate. The appropriate method is the one that requires the minimum cost to determine comparability.
It is important to note that the coverage testing for reconfiguration has a different objective than the testing necessary for acceptance of a new system. For a new system the objective is to verify the vendor has delivered to specification in all parts of the coverage area promised. New system acceptance may require an extensive drive test using a grid with thousands of data points and is quite different from comparing coverage before and after reconfiguration.
For reconfiguration, the testing must verify that coverage is comparable immediately before and after reconfiguration to new frequencies. To be valid, these measurements must be performed as close together in time as the reconfiguration will allow in order to minimize the effect of seasonal changes and other potential environmental differences.
In many cases measurements performed at repeater sites are sufficient. In cases where drive testing is appropriate, the test grid should be designed to use the minimum number of grids to be statistically valid for comparison. There may be specific conditions or system designs that cause some licensees to believe these methodologies will not determine comparable coverage in their system. For those cases the licensee must describe why they need to use a different methodology to show comparable coverage and specifics of the methodology they propose. The focus of any testing must be on showing if comparable coverage is achieved. The three methodologies are general guidelines, and licensees should develop a specific Method of Procedure (MOP) for their test environment to include specific pass/fail criteria.
These guidelines will be considered when the TA reviews FRAs. Licensees are advised that pursuant to the FCC's R&O, all costs related to reconfiguration, including those regarding system testing, must be agreed with Sprint Nextel.
Method 1: Repeater Site Measurements
This method is appropriate for sites where reconfiguration does not require substantial changes to the antenna or coax feed line. This method can be used if other transmission elements, such as transmitter combiners or filtering devices, change, if those changes do not result in a change to the transmit power into the feed line. For those systems where the transmit power to the feed line does not change, it is sufficient to make a series of measurements at the repeater site. This method assumes all existing equipment is specified to operate with comparable losses for the new channels compared to the existing channels. If the antenna bandwidth specifications include the new channels, then the radiated pattern and signal strength should not change, assuming that equivalent transmit power is delivered to the antenna.
Prior to reconfiguring the site, measured losses for each component are recorded including the transmit power entering the transmission line. The measurements should include the return loss of the transmission line and antenna. After reconfiguration, the same measurements are made and compared to the prior measurements. If the two sets of measurements are comparable, then coverage will be comparable.
As an example, assume the site is configured with a base station transmitter feeding a transmit combiner and then a duplexer that feeds the coax line and antenna. The base station receiver receives signals from a receiver multi-coupler that connects to the duplexer and the common antenna.
The transmit power will be checked and recorded at the output of the base station, at the output of the combiner, and at the output of the duplexer before any frequency changes are made. In a similar manner the effective receiver sensitivity (12 dB SINAD or other appropriate test) is measured and recorded at the receiver input, multi-coupler input, and the duplexer input. The antenna feed line and antenna return loss or other appropriate measurements are then made and recorded to determine that those components are functioning correctly.
After the frequency change, the above measurements are then repeated and compared to the first set of measurements. If the two sets of measurements are comparable, then the system coverage is comparable.
Method 2: Line-of-Sight Measurements
This method is appropriate for many systems or sites with a change in the antenna configuration. The measurement accuracy of this method is generally better than a drive test as the multi-path variability is minimized and accurate signal strength changes can be determined by using good quality measuring equipment. This method begins with the measurements in Method 1. Start with making and recording all the pre-reconfiguration measurements specified in Method 1. Then a series of static line-of-sight measurements are made before and after reconfiguration to verify comparability of the new antenna pattern. Typically this method employs eight locations evenly spaced around the site (assuming an omni directional antenna).
Each location should have a line-of-sight path to the radio site. Measure the signal strength from the site, using a narrow beam-width directional antenna and a calibrated measuring device before reconfiguring the site. Next, make and record the measurements in Method 1 after the frequency change and repeat the signal strength measurements at each measuring location. If the measurements are comparable, the antenna patterns and gain match and the coverage will be comparable. If a directional and/or a down-tilt antenna is used at the radio site, the locations should be modified as appropriate for the antenna pattern.
Method 3: Drive Test
This is the most complex and expensive method for determining comparable coverage. Typically, it is only appropriate for complex systems, such as those using simulcast technology, or where extensive changes are made to the antenna and other transmission subsystem elements. Before deciding this method is required, consider the extent of changes to determine if Method 2 is more appropriate and provides better measurement accuracy.
The drive test must be set up to be repeatable and based on a statistically valid method of measurement that minimizes the number of grids to be measured. As with the previous methods, testing should be performed immediately prior to and after rebanding to ensure location variability is minimized. The test need not include building penetration tests if the measurement grids are designed to show the signal strength around the buildings. If the signal levels are comparable in a statistically valid random number of grid areas throughout the coverage area, then signal levels should be comparable in areas not measured.
To be valid, this test should employ automated signal strength measuring equipment and employ the following characteristics:
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1. The measuring equipment should average measurements over 40 wavelengths with 50 samples per average. |
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2. The measuring equipment should include appropriate filters and high quality receivers. |
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3. The service area to be measured should be divided into uniform grids. The number of grids should be the minimum required to verify coverage and be statically valid. |
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4. The baseline measurements should be collected immediately prior to reconfiguration and the post-reconfiguration measurements collected immediately after reconfiguration. This will ensure comparable testing. |
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5. This only compares existing service coverage to post-reconfiguration coverage. If a service hole existed prior to reconfiguration, it will exist after reconfiguration. All coverage comparisons should have a statistically valid basis. |
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6. Before and after rebanding, field audio or bit error rate (BER) checks - to verify simulcast overlap distortion is unchanged - are acceptable. These checks should be conducted while collecting the signal strength data. |
The TA recognizes that 800 MHz licensees face a wide range of system
configurations and circumstances. If a licensee believes more extensive
testing is required than indicated above, they should submit an explanation
of their particular circumstances and detailed Method of Procedure (MOP)
with their Cost Estimate. Licensees are especially advised to question proposals
to conduct drive testing for simpler system configurations.
For additional information on verifying comparable coverage for reconfiguration, please consult your system vendor. For more information regarding coverage testing, please refer to: http://www.pericle.com/papers/index.html, Guidelines for Conducting Drive Test Surveys for 800 MHz Rebanding (with a further bibliography) and also TIA TSB-88 (latest revision) Section 7.
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