June 7, 2016
In late April of this year, the Federal Communications Commission (FCC) announced that it had completed the first phase of the 600 MHz band incentive auction, and that it had reached its clearing target of 126 MHz. This initial stage is being called a “reverse auction” because it asked the TV broadcasters to provide spectrum that will then be offered to wireless telecom carriers in a traditional “forward auction.” This creates an unusual test and measurement challenge for wireless carriers, as depending on geographic location the entire spectrum offered in the forward auction is not free of interference – and that could affect the auction pricing.
The FCC band plan defines the 10 paired spectrum blocks (5x5 MHz each) that will be auctioned. Based on location, the FCC then defined 416 “Partial Economic Areas” (figure 1) and will sell multiple paired blocks in each area. Under certain conditions, RF signals can propagate across distances, so the FCC analyzed the geographic paired blocks to determine their level of impairment from TV stations that are not going off the air and assigned the paired blocks to two categories. The blocks in Category 1 are estimated to have from zero to 15 percent impairment, and Category 2 blocks are estimated to have greater than 15 and up to 50 percent impairment. This designation is critical as it affects pricing – for each percentage of impairment the FCC will discount the forward auction price by one percent.
Blocking Out the Country
In total there are 4,048 paired blocks; the FCC estimates that there are 4,030 Category 1 blocks, and 18 Category 2 blocks. The government agency has also claimed that 99 percent of the Category 1 blocks will not be impaired. Of course, these are estimates based on modeling and propagation prediction – reality will vary. Bidders are going to want to verify on their own that (for example) a paired block estimated to be 8 percent impaired doesn’t actually have over 18 percent impairment when unusual propagation conditions exist between areas. If this were the case, a carrier might offer less – or even in extreme cases choose to not bid. Would you bid on a car if there was a chance it might not run?
There is a financial incentive to proving that a block is impaired beyond FCC estimates, but of course the effort to confirm this has a cost – so a balance must be struck. Four hundred sixteen areas and 100 MHz are a lot of ground and spectrum to cover. Hiring legions of RF analysis engineers to drive around the country and conduct tests is cost-prohibitive. Plus, unusual propagation can occur at odd times, and can be dependent on weather, so these engineers would need to be testing 24/7 over the course of a year or more.
Fortunately, a better solution exists. Remote spectrum monitoring tools such as the Anritsu MS2710xA can be deployed to monitor spectrum within an area, record that spectrum over time, and generate alerts when unexpected signals are detected. Remote spectrum monitors allow small teams to cover very large areas without incurring travel costs.
There is an on-going benefit to these tools, as well. After the auction is complete, operators can repurpose the system of remote spectrum monitors to check for unusual propagation to optimize the network and realize a greater return on the spectrum investment.
To learn more on this potential interference issue and the benefits of using remote spectrum monitoring tools, you can download a free primer entitled Locating and Identifying Cable TV Interference from Anritsu.