A primer for finding and securing radio spectrum
A primer for finding and securing radio spectrum
This article originally appeared in print with the headline, "The long and winding road."
When a public-safety or business entity chooses to secure its communications requirements through a local, regional or national communications service provider, there is little thought given to the spectrum on which their voice and data transmissions will be carried. It is understood that the geographic coverage and system capacity provided — at least by the major national communications carriers — will meet their needs, resulting in reliable and readily available communications.
Such capacity and coverage issues have become less important acquisition drivers for those who elect to satisfy their communications needs through national carriers. But these questions never should be taken for granted by operators of private land-mobile systems that are deployed in the various bands allocated for such purposes under the FCC’s Part 90 rules.
Not very long ago, the task of aspiring FCC licensees was comparatively easy. They would work with communication-technology vendors to match system design features, coverage requirements and pricing scenarios. Once this critical step was complete, they would work to secure the channels that were required by the system, an equally critical step.
In an entirely analog world, the decisions that had to be made were fairly simple: they had to decide whether a conventional or trunked system platform was necessary; if the latter, they had to determine whether the trunked system would provide decentralized or centralized trunked capability. The last part of the decision-making process was to secure frequency coordination and then, of course, secure an FCC license to the spectrum.
For the most part, securing access to sufficient spectrum capacity to deploy successfully a private land-mobile communications system was not a particularly difficult or annoying process. But that may not be the case today.
Depending on the desired frequency band chosen to fuel a communications system, and regardless of complexity, aspiring licensees now may face numerous impediments, such as:
- Local spectrum scarcity;
- Complex FCC rules that are open to interpretation;
- Incumbents that have yet to narrowband their systems;
- Non-optimized digital systems on shared channels;
- Multiple memorandums defining frequency-selection procedures executed by and between some — but not all — certified frequency-coordination committees;
- A growing emphasis on system-engineering analyses;
- Multiple license-application freezes initiated by the FCC (some of limited remaining value);
- The disparate views of myriad advisors;
- The task of determining whether letters of consent are required;
- The potential administrative horrors of securing Canadian clearance (as applicable);
- Regional spectrum-management mechanisms, among other spectrum-access issues.
Given these varied and unpredictable factors, it is suggested that the spectrum component of the wireless communications selection-and-implementation process be considered early and often. There are few spectrum guarantees these days, and the potential to access exclusive-use channels in desired bands should be identified and licensed even prior to system deployments. The Part 90 spectrum environment changes daily, and what appears to be available today probably won’t be available tomorrow — much less next week or next month.
It is further suggested that vendors, when responding to an RFP, not only respond to the technical and financial requirements, but they also should provide a somewhat-detailed spectrum solution, even if it is not a requirement of the RFP. Information on specific frequencies, when access may be pursued, how the channels support the system requirements, and under what circumstances frequencies may be secured and authorized should be supplied. A technical proposal that appears to be outstanding on the surface may be corrupted later, when it is discovered that there is insufficient and/or unreliable spectrum available to accommodate system requirements.
It seems equally prudent for customers to require spectrum guidance from their vendors, for numerous reasons. Succinct responses to spectrum-requirement inquires should provide comfort to customers that recognize that wireless systems function best with optimum spectrum solutions. Customers immediately should be suspicious of responses that sound like, “No problem, there are plenty of channels available that you can get your hands on to support this system” — maybe so, maybe not.
There is little benefit to push spectrum considerations to the last minute, as there are simply too many surprises that can affect system investments negatively. Design the system, and then seek the spectrum solution that best accommodates that system. Ask yourself whether there is more than one band that would suit system objectives. If necessary, consider modifying the system to optimize spectrum solutions.
For example, if desired sites do not provide positive spectrum results or necessary coverages, consider alternative sites. If desired transmitter power levels limit channel availability, consider lowering the power levels to minimum acceptable requirements. Prepare a matrix of all sites—at various power levels and all associated available channels, both shared and exclusive—that would accommodate system priorities. There is no benefit to guessing what channels may or may not be available.
If incumbent licensees exist that are affiliated with your business, provide that information to your frequency advisory committee of choice, as sharing frequencies with “friends” may be better than sharing with unaffiliated incumbents that may not appreciate your spectrum rights. If sharing channels is necessary, share them with incumbents that are operating technology platforms that are similar to that being installed, to reduce the potential for nuisance or unintended harmful interference. But make these spectrum-altering determinations early in the process to avoid unintended consequences, such as higher system-development costs and a lack of desired spectrum, and to keep exceedingly long license-application and license-approval processes to a minimum.
As noted earlier, each Part 90 band has its own set of peculiar requirements and considerations associated with fulfilling spectrum objectives. The following provides a 50,000-foot view of the most popular bands; of course, geographic location is a primary factor in determining spectrum availability.