TA releases coverage testing guidelines
After almost a year of questions regarding drive tests, the 800 MHz Transition Administrator finally released its official guidance on coverage testing to determine that a licensee’s system performance after rebanding is comparable to its present performance.
The verdict: Sprint Nextel likely will pay for drive tests only in a few circumstances. A TA fact sheet states that a drive test to determine coverage “is typically only appropriate for complex systems using simulcast technology or where extensive changes are made to the antenna and other transmission subsystem elements.”
Given that licensees are supposed to use a testing method “that requires the minimum cost to determine comparability,” most do not need an expensive drive test, according to the TA fact sheet. Instead, licensees should conduct repeater-site measurements when rebanding does not require “substantial changes to the antenna or coax feed line” and line-of-sight measurements in most other cases.
However, TA Director Brett Haan has emphasized that all aspects of rebanding will be considered on a case-by-case basis, so a licensee is free to make a case that specific circumstances surrounding its system justifies the more expensive comparable-coverage test. It’s an option licensees should consider pursuing, said Billy Carter, Region 54 chairman and APCO coordinator for Northern Illinois.
“We want to make sure that the coverage we had is the same that we’ve got now,” Carter said. “There’s no way to determine that by just measuring the power out of the transmitter. … In order to determine whether the system is propogating the same from that particular site on that particular frequency, you need to do a drive test.”
For example, an antenna in a given system may have been optimized to perform at a licensee’s current operating frequency. Although the licensee’s post-rebanding frequency is relatively nearby on the spectrum chart, there is a chance that the antenna would not propogate signals as well at the new frequency, Carter said. Because no one wants to accept the potential liabilities associated with such a glitch, the only way to be certain is to conduct a drive test, he said.
“You have to verify the reliability of the system — you can’t guess,” Carter said. “The reason for the field-strength test is to make sure we haven’t lost any of the capabilities we had before [rebanding].”
Another key aspect included in the fact sheet is that coverage tests should be conducted “immediately before and after reconfiguration.” Some licensees previously had expressed concern that such an approach would lead to inaccurate assessments of larger systems because the foliage environment could change greatly during the lengthy rebanding of a large system.
But a TA spokesperson said coverage tests should be conducted on a site-by-site basis as a system is rebanded, meaning that the foliage environment should be similar for both the “before” and “after” tests.
“The intent of the guidance is to minimize the effect of foliage,” the spokesperson said.
Not addressed in the fact sheet was the notion of interference testing, but Carter said his impression was that the TA and Sprint Nextel strongly oppose such tests.
“The reason the interference test probably would not be a valid test is because the area of the spectrum that you’re moving to is far more spectrally separated from the area that was getting the interference originally,” Carter said. “Also, if you do a coverage test and there are any interference products being generated, you’re going to see an anomaly in that test result.”
On another rebanding front, it appears that only a handful of contested rebanding cases from Wave 1, Stage 1, will be forwarded to the FCC, the TA spokesperson said. Of the 19 cases involving licensees operating in Channels 1-120 that were not resolved during the mandatory mediation process, licensees and Sprint Nextel have reached agreements in 12 instances and were awaiting TA approval as of press time. In two cases, the parties have requested additional time to forge a deal.
Five cases have been submitted to the FCC, the TA spokesperson said. Although the TA-assigned mediator has recommended a solution in each case, the FCC will be given a full case history and is allowed to resolve the disputes in a manner it deems appropriate.
|1.||Repeater-site measurements: “Appropriate for sites where reconfiguration does not require substantial changes to the antenna or coax feed line.”|
|2.||Line-of-sight measurements: “Appropriate for many systems or sites with a change in the antenna configuration.”|
|3.||Drive-test measurements: “Typically only appropriate for complex systems using simulcast technology or where extensive changes are made to the antenna and other transmission subsystem elements.”|
|Source: 800 MHz Transition Administrator|