Key Developments in Frequency Use for Public Safety Services

David A. Case
FCC addresses frequency use and other critical issues surrounding the need for better communications for public safety services.

In the light of the events of 9/11, a new focus on homeland security has emerged. Under the homeland security umbrella are issues such as airport security and data security.

One critical area being addressed is communications. In part, this focus is based on lessons learned about what did and what did not work in terms of the communication technology critical to providing emergency communications. With the need to provide critical information to emergency services, terrorism has had a profound new effect on public safety communications and services.

Understanding the Issues

Before a discussion can begin, one needs to define public safety services and what they encompass. For this article, public safety services are defined as those that provide communication for law enforcement, fire, rescue, and other emergency-oriented services.

What makes public safety communications complicated is that although the systems are regulated under FCC Part 2 and Part 90 of the technical rules (and licenses are issued by the FCC licensing office), state agencies and local municipalities also have a hand in this process.

Therefore, even though FCC has designated some frequencies for statewide use to provide communication coordination, it is possible that a municipality may forgo this equipment and opt for systems that provide communication only to local services to reduce costs. This is often the case for rural or small fire, rescue, or police services, and so their equipment is incapable of communicating with services in surrounding areas.

Frequency Bands

The frequency bands for public safety can be found in the Code of Federal Regulations number 47, telecommunications. The FCC table of frequency allotments can be found in Section 2.106.

In reviewing the FCC frequency chart, a majority of the public safety frequencies are below 1 GHz and, specifically, below 525 MHz. FCC has also designated parts of the 700 and 800 MHz bands for use by public safety services. A couple of bands above 1 GHz have also been allotted.

30­50 MHz 72­76 MHz 150­170 MHz 220­222 MHz 450­470 MHz 470­512 MHz 764­776 MHz 794­806 MHz 806­824 MHz 851­859 MHz 929­930 MHz 1427­1435 MHz 2450­2500 MHz 10,550­10,680 MHz

Table I. Public safety frequency pool.

These services operate under Part 90 of the FCC rules. Part 90.20 addresses the specific bands of operation under the public service safety pool. The specific frequency bands of operation are listed in Table I.

FCC also established the National Frequency Coordination Committee to address operational and technical parameters for public safety systems operating in the 700 MHz band. FCC also developed national and regional plans for the 700 and 800 MHz bands.

The additional coordination that can be undertaken on an intrastate level (or even at the county or local-agency level) creates the possibility of even more frequency coordination problems.

Operation Requirements

As mentioned earlier, these services function under Part 90 of the FCC rules. Such services operate under the Private Land Mobile Services rules and are a licensed service. Their operation is restricted to those entities that meet the eligibility requirements as defined in Section 90.20 of the technical rules.

Operation under this service is protected from receiving any harmful interference. It should be noted that the FCC definition of harmful interference references interference to the public safety bands.

Operation in most of these bands is limited to narrowband operations using either 25-, 12.5-, or 6.25-kHz-wide bandwidth requirements. In most cases, operation is also limited to specific band channelization. Part 90 addresses transmitter power output, modulation, and other characteristics of the radios in the different frequency bands.

Going Forward

If a public safety service is using older crystal-tuned radios (some still are) with the operation confined to narrowband channels and different frequency assignments, problems are much more likely to occur at some rescue scenes. Fortunately, these problems are being addressed by industry.

CFR 47 Part 90 Subpart B: Public Safety Radio Pool   Source: 62 FR 18845, April 17, 1997, unless otherwise noted. § 90.15 Scope. The Public Safety Radio Pool covers the licensing of the radio communications of governmental entities and the following category of activities: Medical services, rescue organizations, veterinarians, persons with disabilities, disaster relief organizations, school buses, beach patrols, establishments in isolated places, communications standby facilities, and emergency repair of public communications facilities. Entities not meeting these eligibility criteria may also be licensed in the Public Safety Radio Pool solely to provide service to eligibles on one-way paging-only frequencies below 800 MHz, i.e., those frequencies with the assignment limitations appearing at § 90.20(d)(13) or (d)(60). Private carrier systems licensed on other channels prior to June 1, 1990, may continue to provide radio communications service to eligibles. Rules as to eligibility for licensing, frequencies available, permissible communications and classes and number of stations, and any special requirements are set forth in the following sections [of Part 90].

Currently in the state of Ohio, for example, there are problems with communications between some local municipalities as well as problems communicating with some of the state services. There is a new system proposed to address this; however, in some counties, some agencies and residents are balking at upgrading to a system that can communicate statewide because of the high cost to implement such systems.

FCC is also addressing some public safety issues through Notices of Proposed Rulemaking (NPRMs). FCC recently released an NPRM that affects Sections 90.20 and 90.175 addressing frequency coordination for frequencies below 479 MHz. There is no doubt that frequency use for public safety will also be addressed by homeland security experts. These experts can help ensure that public safety personnel can communicate across agencies.

Additional information can be obtained from the FCC Wireless Bureau at http://www.fcc.gov and, more specifically, the FCC Public Safety Web site at http://wireless.fcc.gov/publicsafety/.

On April 23, FCC acted on a Memorandum Opinion and Order and the 3rd Report and Order (FCC 03-99). These orders address the use of the 4940­4990 MHz band for public safety. Uses include broadband mobile operations, fixed hot spots, and temporary links on a primary basis for public safety.

FCC is starting to review comments filed as part of NPRM 02-302 on the use of the 5850­5925 MHz ITS band for public safety use by ITS-based systems.

David A. Case, NCE, NCT, is senior radio compliance engineer for Cisco Systems Corporate Compliance and EMC Standards Group. He can be reached via e-mail at davecase@cisco.com.