he local and state public safety community has been requesting additional spectrum from the Federal Communications Commission (FCC) since the 1960s, as wireless communications has become a larger and larger part of the critical supporting technologies required to respond to the public safety incidents that occur every day in the United States. This need was driven by technological innovations that allowed wireless to be used in new and innovative ways. Probably none of these was as important to the individual officer, and to the demand for more spectrum, as the development of the personal portable two-way radio (the handy talkie) that is today a mainstay of public safety. This need continues to expand, with the new technologies of the 21st century, including full-motion video and high-speed data. Providing critical public safety communications support requires the availability of sufficient and appropriate radio spectrum.

As technology moved forward, multijurisdictional responses highlighted the need for interoperability, the ability of agencies to speak directly over the radio with members of neighboring public safety agencies on demand, in real time. In recent years, data communications also entered this arena.

Importantly, until the chartering of the Public Safety Wireless Advisory Committee (PSWAC) by the National Telecommunications and Information Administration (NTIA) in 1995, no long-range planning effort involving general input from the public safety user community was ever undertaken by the FCC.

All radio services use Private Wireless bands regulated by either the FCC for non-federal licensees, or by the NTIA for federal government agencies.¹ To address spectrum needs, these agencies identified three options: (1) allocating additional spectrum to public safety, (2) increasing the efficiency of public safety's existing spectrum by narrowing the width of radio channels, a process known as "narrowbanding," or (3) doing both. Because radio band congestion and the competition for that finite spectrum resource make allocating additional spectrum in bands that are accessible to today's equipment a complicated process, the FCC and the NTIA determined that increasing spectrum efficiency through narrowbanding was the best way to meet growing public safety spectrum requirements. Once narrowbanding has been completed, the vacated spectrum between channels can be reassigned; this process is often called "refarming." Thus, the FCC and NTIA began narrowbanding initiatives, while continuing to explore additional spectrum allocations in other bands, such as 700 MHz² and 4.9 GHz. Because most public safety agencies at all levels of government operate in the VHF and UHF bands, these bands became the targets for refarming.

Beginning in the early 1990s, a series of regulatory actions occurred as part of these initiatives. To encourage spectrum efficiency the FCC initially established a timeline requiring local and state public safety agencies to migrate (in aggressive interim steps) to narrowband by January 1, 2018,³ while NTIA established a timeline requiring federal agencies to migrate to narrowband by January 1, 2008, in an attempt to conserve spectrum. These differing transition dates had the potential for a major negative impact on public safety users by placing local and state users on a different timeline than federal users, resulting in a lack of interoperability across all levels of government if not coordinated properly. Consequently, as federal agencies move towards narrowbanding, they will have to plan and budget for interim measures to permit interoperability with state and local agencies likely to still be using wideband systems.

Although narrowbanding does not affect Private Wireless voice quality, it does have an undesirable effect on low speed data messaging by reducing data rates. Moreover, altough narrowbanding will achieve spectrum efficiency for voice communications, it does not alleviate the need for additional public safety spectrum to support the growing demands of additional public safety services and the need to implement new technology solutions. In the long-term, public safety communications will increasingly rely on broadband data as it transitions toward communications based on Internet Protocol (IP). An overview of the technical processes involved in spectrum and narrowbanding is included at the end of this article.

Increasing Spectrum Efficiency
The history of VHF/UHF spectrum management has been one of gradually narrowing channel bandwidths as technology improves. For example, the original VHF channels had a much larger bandwidth of 120 kHz. On December 23, 2004, the FCC codified the current narrowband requirement of 12.5 kHz by January 1, 2013. Narrowband equipment meeting this requirement has been available for some time in both conventional analog FM and digital formats and is probably fielded today in most public safety agencies, though it may be operating in wideband (25 kHz) mode.

Though overly simplified, figure 1 illustrates the net effect that this narrowbanding effort will have on available operating channels when it is completed.

Current Spectrum Licensing and Operation⁴
Estimating the impact of narrowbanding on local and state agencies requires a baseline study of existing licenses. The baseline was built using FCC databases available through its Universal Licensing System (ULS). As of August 31, 2004, the ULS database listed 112,240 active Private Wireless licenses issued to government entities in the public safety pool. Most are conventional, or nontrunked, systems, as depicted in figure 2. Of these, 54 percent are VHF and 33 percent are UHF, showing that most public safety licenses (87 percent) are in the affected bands. Only the VHF and UHF bands are affected by narrowbanding.

How are these channels being used now? The FCC ULS database shows that 84 percent of VHF/UHF licenses are used for voice only and 12 percent for data only, with the remainder carrying a combination. Of these assigned channels, 86 percent are greater than 12.5 kHz in bandwidth. Figure 2 shows that most VHF/UHF licenses are for wideband voice transmissions.

FCC Regulatory History on Narrowbanding
In 1995, in its first Refarming Report and Order,⁵ the FCC adopted measures to promote highly effective and efficient use of the Private Wireless spectrum and facilitate the introduction of advanced technologies into the Private Wireless services. The rules provided that, in order to effect a transition from a wideband (25 kHz) channel plan to a narrowband (12.5 kHz) channel plan, the FCC would approve only increasingly spectrally efficient equipment. Specifically, after February 14, 1997, the FCC would approve new models of equipment for wideband operations only if they were also capable of operating on 12.5 kHz or narrower channels. Further, after January 1, 2005, the FCC proposed to approve equipment for 25 kHz or 12.5 kHz channels or both only if it was also capable of operating on 6.25 kHz or narrower channels. At that time, the FCC specifically declined to implement a comprehensive set of dates mandating strict manufacturing and licensing requirements, or to require users to replace existing wideband systems even though "dates certain" were requested by licensees.

In 2003, in the Second Report and Order ⁶ on this same subject, the FCC concluded that initial refarming rules had not resulted in the desired efficiency of use of spectrum in the 150-174 MHz and 421-512 MHz bands and that further action was required. Consequently, the FCC again amended its rules to provide a schedule for the migration of Private Wireless systems to narrowband technologies. No applications for new wideband 25 kHz systems or geographical expansion of existing wideband systems could be filed after January 13, 2004.

Eighteen petitions for reconsideration were filed by licensees and national public safety organizations. The Association of Public-Safety Communications Officials International (APCO International), joined by NPSTC⁷ and the leading organizations representing the leadership of police and fire departments across the nation, including the International Association of Chiefs of Police (IACP), the Major Cities Chiefs Association (MCC), the National Sheriffs' Association (NSA), the Major Counties Sheriffs Association (MCSA), and the International Association of Fire Chiefs (IAFC), requested an immediate stay of the 2004 deadline pending resolution of the petitions for reconsideration. At issue in these stay requests was the commission's decision to prohibit any applications for new operations using wideband channels operating in the 150-174 MHz or 421-512 MHz bands, and allowing incumbent wideband (25 kHz) licensees in these bands to make modifications to their systems only to the extent that their respective authorized geographical is not expanded as a result. The FCC subsequently stayed this portion of the order pending resolution of all petitions for reconsideration.

On December 23, 2004, the FCC released the Third Memorandum Opinion and Order and Third Further Notice of Proposed Rulemaking and Order. It addressed the 18 petitions for reconsideration of the rules adopted in the Second Report and Order in this proceeding to promote migration to narrowband (12.5 kHz) technology in the Private Wireless services. Also, the FCC is seeking comment on a proposal to defer or eliminate the requirement in its rules that certain applications for equipment authorizations received on or after January 1, 2005, specify 6.25 kHz capability. In addition, the FCC stayed the January 1, 2005, date pending resolution of the issues raised in the Third Further Notice.

The critical decisions contained in the Third MO&O that pertain to public safety are as follows:

1)     Applications for new operations using 25 kHz channels will be accepted until January 1, 2011. After January 1, 2011, applications for new operations using a bandwidth greater than 12.5 kHz will be accepted only to the extent that the equipment meets the spectrum efficiency standard of one channel per 12.5 kHz of channel bandwidth (voice) or 4800 bps per 6.25 kHz (data).

2)     Applications for modification of operations to expand the authorized geographic coverage area of an existing station using 25 kHz channels will be accepted until January 1, 2011. After that date, applications for such modification will be accepted only to the extent that the equipment meets the spectrum efficiency standard of one channel per 12.5 kHz of channel bandwidth (voice) or 4800 bps per 6.25 kHz (data) if the bandwidth for transmission specified in the modification application is greater than 12.5 kHz.

3)     The manufacture and importation of any 150-174 MHz and 421-512 MHz band equipment operating on a channel bandwidth up to 25 kHz will be permitted until January 1, 2011. After that date, manufacture and importation of any 150-174 MHz and 421-512 MHz band equipment operating on a channel bandwidth greater than 12.5 kHz will be accepted only to the extent that the equipment meets the spectrum efficiency standard of one channel per 12.5 kHz of channel bandwidth (voice) or 4800 bps per 6.25 kHz (data).

The FCC also revised its Rules to exempt certain paging-only frequencies from narrowbanding requirements. These paging frequencies are generally licensed to commercial services and are widely used by public safety agencies, particularly by volunteer fire-rescue and EMS agencies.

Some local/state licensees operate under FCC license in the federal government bands under the control of the NTIA. A separate ongoing proceeding (ET Docket No. 04-243) addresses whether different narrowbanding requirements are needed to account for the federal government's (NTIA) own narrowbanding plans. The FCC decisions adopted on December 23, 2004 are subject to further modification with respect to those bands and defer decisions on those bands where appropriate.

At this time, little or no opposition to the dates set forth in this last proceeding is anticipated. The actions taken by the FCC in the Third MO&O and FNPRM appear to address the concerns identified by the 18 petitioners that filed requests for reconsideration. The FCC's current requirements, now enacted into their regulations and impacting all VHF and UHF licensees, are summarized in figure 3.

Cost Burden
Figure 4 shows the breakdown of ownership of the 25 kHz licenses in a sample set of the 67 fastest growing counties in the United States. The figure shows that the burden of costs would fall on county and municipal governments, which account for two-thirds of these public safety licenses. This was a major point raised by some of the 18 petitioners to the FCC's Second Report and Order, as discussed in detail below, concerning the near-term cost of replacing their systems at a time when local and county budgets are already stretched thin. The Los Angeles County Internal Services Department stated it would be a "financial impossibility" to upgrade all of their existing wideband equipment in the near-term while maintaining current interoperability levels. Other petitioners noted the potential ripple effect on interoperability. If two neighboring jurisdictions have an interoperability agreement, and one has the financial means to upgrade to narrowband, the other jurisdiction could be forced to follow suit (although they may not have the immediate resources to do so) or lose interoperable capability with their neighbor.

Radio 101 for Police Chiefs
The basic building block of radio communications is the radio wave. Like waves on a pond, a radio wave is a series of repeating peaks and valleys. The entire pattern of a wave, before it begins to repeat itself, is called a cycle. These cycles repeat over time. The number of cycles, or times that a wave repeats in a second, is called its frequency. Frequency is measured in the unit hertz (Hz), referring to a number of cycles per second. One thousand hertz is referred to as a kilohertz (kHz), 1 million hertz as a megahertz (MHz), and 1 billion hertz as a gigahertz (GHz).

The complete range of frequencies that could be used for radio communications is called the radio spectrum. Radio spectrum ranges from approximately 30 kHz to up to more than 300 GHz. Frequencies are grouped in ranges called bands. Bands licensed by the FCC for local and state public safety use are shown in figure 5 and include the HF (high frequency), VHF (very high frequency), UHF (ultra-high frequency), and most recently SHF (super-high frequency) bands. Radio systems operating in the 764-776 MHz and 794-806 MHz portion of the UHF band are referred to as 700 MHz systems and those operating in the 806-824 MHz and 851-869 MHz portion of the UHF band are referred to as 800 MHz systems. Frequencies above one GHz are often referred to as microwave bands.

A radio wave is generated by a transmitter and then detected by a receiver. An antenna allows a radio transmitter to send energy into space and a receiver to pick up energy from space. Transmitters and receivers are typically designed to operate over a limited range of frequencies within a specific frequency band (or bands). Only transmitters are licensed by the FCC. The aggregate amount of local and state public safety spectrum allocated within these bands is about 97 MHz, subject to change pending resolution of re-banding issues in the 800 MHz band within each region of the country.

Within each band, Private Wireless radio systems, including those used by local and state public safety agencies, are licensed by the FCC to operate in particular blocks of radio spectrum called channels. Most legacy public safety radio systems today operate in a channel with a bandwidth of 25 kHz.

Implementation
Moving to narrowband is actually a simple and straightforward process. As shown in figure 6, the center of each channel remains the same as the skirts of each channel are narrowed from 25 kHz to 12.5 kHz in phase 1 (the change required by the FCC before 2013). Later, should the FCC mandate another move in the future to phase 2 (6.25 kHz, now under consideration for a much more distant date), the same move would happen again.

So as not to confuse readers, we note that the VHF high band currently uses 25 kHz equipment, but the centers of the channels are set 15 kHz apart. In the UHF band, 25 kHz equipment is channeled on 25 kHz centers. The VHF band works with this channel overlap by geographically separating the transmitters by a much larger distance than that required for UHF. This same additional separation requirement will exist in the VHF band for both phases of narrowbanding.

Licensing: Analog and Digital
Public safety agencies need to continue aggressively planning a migration strategy. As agencies move to narrowband operations, they must apply for new frequencies or modify their existing licenses. Holding a license for 25 kHz operations does not guarantee the licensee the same frequencies divided into two channels, nor does it guarantee the licensee twice the number of channels; licensees will have to justify their need for additional channels beyond their current allocation. To simply keep the same system configuration, licenses must only be modified to show the new narrowband channel width. If you plan to add new channels, know that these applications are reviewed using the same process as any new license application. Nevertheless, as agencies migrate to narrowband operation, the pool of available frequencies increases as systems use the spectrum more efficiently.

Virtually all digital systems operating in the VHF and UHF bands incorporate some or all of the Project 25 (P25) suite of standards. P25's digital modulation inherently meets the FCC's 12.5 kHz narrowbanding rules and, if properly licensed, should need no further action to comply with FCC rules. But P25 also supports backward operation to 12.5 and 25 kHz analog channel bandwidths to support interoperability. If a system is operating in this mixed mode using 25 kHz channels, the analog 25 kHz channels must be narrowbanded to 12.5 kHz, and all radios appropriately reprogrammed or replaced.

Implications for Police Departments
Forward migration to narrowband can be graceful and seamless if properly planned. Fortunately, most equipment purchased in the VHF and UHF bands over the past 5-7 years is already capable of operating on 12.5 kHz channels. Thus, it is a matter of continued replacement with narrowband-capable equipment until all equipment meets the new mandate. At that time, and after proper re-licensing, equipment can then be reprogrammed to the narrower channels and the migration is complete. This change must happen before 2013.

To prepare for these deadlines, and when considering interim system replacements, Public safety agencies should start assessing their Private Wireless systems and planning for eventual replacement or upgrade. Local and state governments must plan contingencies to accommodate system changes for both public safety and non-public safety systems. Today's tight budgets require no less. While the 2013 migration deadline may seem a long way out, the long lead time and interim deadlines encourage agencies and governments to plan and implement well in advance. ■

¹ Private Wireless, historically called Land Mobile Radio or LMR, refers to radio spectrum used for licensees operating standard dispatch radio systems as compared to Commercial Wireless that typical refers to cellular and satellite radio systems.
² 700 MHz band availability is contingent on existing analog broadcast television stations vacating the spectrum during transition to digital television (DTV).
³ As covered in detail in the remainder of this article, this date was subsequently revised to January 1, 2013.
⁴ Information on Licensing, Operations and Cost compiled by the Center for Naval Analysis for use in the soon-to-be-released Narrowbanding Public Safety Spectrum, a US Department of Homeland Security Project SAFECOM report to Congress in response to House Report 108-169 to the Fiscal Year 2004 DHS Appropriations Bill (PL108-90).
⁵ See Replacement of Part 90 by Part 88 to Revise the Private Land Mobile Radio Services and Modify the Policies Governing Them, Report and Order and Further Notice of Proposed Rulemaking, PR Docket No. 92-235, 10 FCC Red 10076, 10077 2 (2001) (Refarming R&O)
⁶ Second R&O, 18 FCC Rcd at 3038 11-12.
⁷ NPSTC, formed May 1, 1997, is a federation of 13 associations and organizations representing public safety telecommunications. The IACP is a charter member. NPSTC was originally formed to encourage and facilitate implementation of the findings and recommendations of the Public Safety Wireless Advisory Committee (PSWAC) established in 1995 by the FCC and NTIA to evaluate wireless communications needs of local, tribal, state and Federal public safety agencies through the year 2010, identify problems, and recommend possible solutions. NPSTC has taken on additional responsibilities including implementing the recommendations of the Public Safety 700 MHz National Coordination Committee (NCC), an official Federal Advisory Committee to the FCC, and support and development of the Computer Assisted Pre-coordination Database (CAPRAD) system for 700 MHz spectrum planning assistance for the 55 Regional Planning Committees (RPCs). NPSTC develops and makes recommendations to appropriate governmental bodies regarding public safety communications issues and policies that promote greater interoperability and cooperation between Federal, state, tribal and local agencies.

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