1

Desirable Properties of a National Public Safety Network

Draft Report and Recommendations of the 

Visiting Committee on Advanced Technology

of the National Institute of Standards and Technology

November 21, 2011

Introduction

On June 8, 2011, Aneesh Chopra, the United States Chief Technology Officer 

(USCTO), requested that the Director of the National Institute of Standards and 

Technology (NIST) charge the Visiting Committee on Advanced Technology 

(VCAT) of the NIST with the task of developing a summary of desirable features 

that could be incorporated into the design of a national public safety network. The 

subcommittee on Public Safety Networks has met in person and by phone and 

online and several public meetings on this subject have been held in 

Philadelphia, Chicago, and elsewhere1

. NIST also recently issued a request for 

information and comment on “Desirable Features of a Nationwide Public Safety 

Broadband Network.”2

In addition, the USCTO has held coordinating meetings with Federal and other 

agencies and representatives of public safety and other organizations to further 

explore the needs of this vital component of protection for the citizens of the 

United States. The President’s Committee of Advisors on Science and 

Technology (PCAST) has also touched on this topic as it considers the use and 

allocation of broadcast spectrum. The National Research Council recently 

published a report on wireless technology and opportunities for its use3 that 

highlights the rationale for many of the ideas incorporated into this extended 

essay on public safety networking.

 

1 August 10, 2011, w/APCO Meeting, Philadelphia, PA; September 7, 2011, 

w/SAFECOM meeting, Chicago, IL; VCAT meetings, June 7-8, 2011 and October 

17-18, 2011, at Gaithersburg, MD.

2 “Soliciting Input on Research and Development Priorities for Desirable Features 

of a Nationwide Public Safety Network,” Federal Register/Vol. 76, No. 176, 

Monday, September 12, 2011; responses due by October 12, 2011. [Docket No. 

110727437-1433-01]

3 [NRC Wireless] Wireless Technology, Prospects and Policy Options, National 

Academies Press, 2011, ISBN-13: 978-0-309-16398-9, ISBN-10: 0-309-16398-6.
2

It is also recognized that the diverse participants in public safety include a wide 

range of private sector organizations and civilian volunteers and that the 

aggregate also operates, from time to time, in nondomestic emergencies to 

render aid and assistance. The scope and diversity of demands levied on the 

public safety fabric strongly influence the nature of the communications 

infrastructure that is needed to manage and coordinate responses to events that 

challenge public safety.

This extended essay is intended to provide a summary of features that appear to 

the VCAT to be relevant to and potentially useful objectives for the design of a 

national public safety network. This is not a design document, although many of 

the observations are intended to influence subsequent design or designs for a 

national public safety network.

1. Observations and Context

1.1 Scope of Public Safety Community

Public safety is an extremely broad term and encompasses law enforcement, 

response to fire, natural and man-made disasters, medical emergencies, threats 

to public order and a host of other situations. Moreover, the so-called “first 

responder” community is, itself, geographically, jurisdictionally and 

organizationally diverse. Even within the context of the National Incident 

Management System (NIMS),4 chains of command and authority can be 

manifold. In some cases, the usual fire, police, and medical responder cohorts 

are augmented with National Guard and military units, volunteer efforts, and nongovernmental organizations such as the Red Cross, among others. Not to be 

lost, however, is the observation that most incident responses begin in a local 

context but may blossom into a much more complex process for a variety of 

reasons. 

It seems worth observing that “national security” and “public safety,” while 

overlapping, are not coincident. The former is generally concerned with external 

threats that may, of course, also threaten domestic public safety. Public safety 

includes concerns for natural disasters, accidents and deliberately harmful acts. 

In many cases, the assets of the military and civilian organizations are drawn 

together to cope with situations beyond the capacity of either separately. The two 

regimes function with sometimes significantly different and even conflicting or at 

least incompatible policies, making the problem of coordination more complex 

and potentially affecting system designs for interoperability across a broad 

spectrum of actors.

 

4 http://www.fema.gov/emergency/nims/
3

At least one commentator5 observed that achieving public safety is hard because 

the effort is fragmented across the country. No single entity is in charge across 

the entire public safety enterprise, and solutions are expensive. Leadership is 

needed and costs need to be reduced. The classic “name a Czar” solution is not 

likely to work, either. Frameworks for cooperation that can build on common 

planning, standards, technology, budgeting and practices seem to be the most 

productive avenues for progress.

There are estimated to be 14,000 police departments, 3,000 sheriff’s offices, 

more than 6,000 911 centers, 65+ Fusion Centers, 1.2 million employees in city, 

county, state, and Federal law enforcement and 800,000 in private-sector 

security in the United States. These 2 million people worry about public safety for 

over 300 million citizens: a ratio of 150:1. Anything we can do to increase the 

efficiency and effectiveness of our public safety sector will benefit everyone.

1.2 Modern Communications

Coordination requires more than voice communication in this second decade of 

the 21st Century. It incorporates data, voice, and video communication and in the 

packet environment of the Internet, these are largely indistinguishable at the 

packet level. Indeed, it has become helpful if not vital and necessary, to equip 

emergency responders with access to the contents of the World Wide Web and 

to specialized and possibly access-controlled sources of information to aid in 

response to particular emergencies. As devices become part of the growing 

Internet, emergency responders may well need to have access to and even 

control over devices for surveillance and remote actuation. 

Implicit in these observations is the apparent need for standards that will permit 

interoperation of communication devices and systems across a broad swath of 

actors in the public safety landscape. That these standards would benefit from 

international scope should be apparent, in the interest of facilitating responses to 

nondomestic emergencies, and taking advantage of larger markets to drive costs 

down through economies of scale.

1.3 Resilience, Robustness and Recovery

Without question, communications in support of public safety must be reliable, 

especially under stressed conditions, including, for example, loss of power, loss 

of infrastructure and lack of operating personnel. It seems appropriate to observe 

that this objective may be met not only through redundant provisioning but also 

through rapid deployment of temporary or even permanent infrastructure. Not 

only will first responders need rugged equipment but they will also need an ability 

 

5 John Gustafson, private communication
4

to deploy auxiliary or replacement gear quickly, at need. The utility of common 

standards should be obvious in this context – national, state and local-level 

caches of common equipment will be far more feasible if standards that permit 

interoperability can be established, adopted and applied. 

It is also worth observing that operating conditions in emergencies are usually far 

from optimal, leading to the need for rugged gear that can be operated handsfree or with one hand and with protective gear in place including gloves. It is also 

important to recognize that not every piece of gear associated with emergency 

response has to have the same degree of ruggedness. There are in-vehicle 

devices, command centers and remote information processing sites that may be 

protected from the worst conditions and therefore able to operate with 

commercial quality equipment. A key objective, again, is for all equipment and 

systems to be able to interwork at need.

At least one participant in the public meetings suggested the creation of selfsupporting “Regional Resilience Networks” acting as emergency communications 

utility companies that could be interconnected, possibly through commercial 

backbones. Such systems in the 25 largest coastal metropolitan areas would 

cover approximately 100 million of the 330 million U.S. population. In a related 

observation, the incorporation of private sector facilities, organizations and 

resources into national scale planning for public safety could lead to cost sharing 

and increased coherence. 

1.4 Security, Authentication and Access Control

Generally speaking, access to emergency communications (including information 

sources, surveillance devices, remote control systems and so on) has to be 

managed. This implies that some kind of authentication is needed to validate a 

participant in emergency or public safety response. As has been suggested in 

section 1.1, a wide range of potential participants may require validation, and that 

rapid and reliable means to authorize responding actors will be particularly 

helpful. A variety of mechanisms may be invoked to achieve this objective, but it 

seems important to suggest that relying solely on such methods as user names 

and passwords may be naïve if not seriously risky. Again, the need for broadly 

applicable standards is clear, as are distributed methods for authentication to 

avoid the potential clumsiness and latency of overly centralized management. 

Pre-authorizations may prove useful as well as mechanisms that support and 

validate inter-organizational trust. It may also be worth considering the notion of 

identity according to “role” in addition to “person” to aid in pre-configuring 

communication and authentication system responses to particular kinds of 

incidents. 
5

Homeland Security Presidential Directive 12 [HSPD12]6 represents a major 

initiative towards establishing common standards for personal identification within 

the Federal Government. Many of the ideas contained within this framework are 

potentially relevant to the problem of authentication in the context of general 

emergency services and should be taken into consideration. 

1.5 Cost

Among the most serious barriers to effective emergency response is the cost of 

equipment, systems, maintenance and training in support of first responders. 

While there are many components that contribute to cost, there is a need to 

balance functionality and cost. Again, the potential value of common standards 

seems clear because they promote interoperability and competition. The design 

of the public safety network and the gear needed to exercise it must take into 

account realistic limits to affordability. Bulk purchases and national-or state-level 

warehousing may help to drive some costs down through economy of production 

scale. 

It is also worth recognizing that commercial, “smart phone” platforms have 

produced substantial creative energy for development of useful applications. The 

notion of a land-mobile radio as a smart platform and designing that notion into 

the system seems very attractive as a way to facilitate public safety features and 

applications, many of which may be developed by the public safety community 

itself. 

Use of commercial, off-the-shelf equipment, adapted or augmented perhaps to 

support specific emergency service needs, is also attractive and the next section 

explores this avenue briefly.

1.6 Interoperation with Commercially Deployed Systems

The currently apparent vector for a national public safety network acknowledges 

and builds on the anticipated deployment of the commercial, wireless Long Term 

Evolution (LTE) broadband standard. It is arguable, however, that a national 

public safety network will likely have needs that extend beyond deployed 

commercial system(s) and that, even if augmented with LTE components (cell 

towers, etc.) that are prioritized for public safety use, a robust and reliable system 

may need components that extend beyond the LTE operational envelope. For 

example, the need for peer-to-peer (“talk around”) capability and some form of 

relay capability might drive such extensions. An assumption in the remainder of 

this essay is that such extensions are worthy of exploration and may require a 

 

6 http://www.dhs.gov/xabout/laws/gc_1217616624097.shtm
6

combination of research, experimentation and prototype deployment for testing 

and evaluation. 

In addition, it can be imagined that commercial equipment might be applied to 

serve emergency needs, potentially realizing cost savings. Smart phones could 

be equipped with applications and augmented to interwork with public safety 

equipment, especially where the use is in relatively benign environments.

1.7 Role of 911 and Other Online Public Safety Systems

The national public safety system is triggered into action through a variety of 

signals. Among the most common and important is the 911 telephone system,

which has been extended over time to include mobile devices that can be located 

through proximity to specific base stations and, in many cases, the use of the 

Global Positioning System (GPS). That a national public safety network design 

needs to take into account the 911 system seems obvious. However, the 911

concept itself may well evolve as Internet-enabled devices become part of the 

online landscape. Hazard detectors that “know where they are” and can access 

the Internet may be able to announce emergencies automatically. Mobile phones 

may learn their precise location in public places such as hotel rooms from local 

announcements literally made by the room itself. The Federal Communications 

Commission (FCC) focus on location accuracy illustrates the richness of potential 

location-based designs.7 There are many scenarios that invite creative means for 

improving the effectiveness and precision of the 911 concepts and a national 

public safety network design should take advantage of these possibilities. 

Civilians may become key sources of information in aid of incident response and 

their inputs need to be accounted for in the design of the information systems 

supporting public safety systems.

1.8 Frequency Allocations

Current frequency allocations assign 763-768 MHz and 793-798 MHz for base 

station and mobile unit use, respectively. The so-called “D” block would expand 

this allocation to include 758-763 MHz and 788-793 MHz to base station and 

mobile use, respectively. In addition, the public safety net communication 

requirements are also served with allocations in the 769-775 MHz and 799-805 

MHz bands in 12.5 KHz narrowband increments. These latter allocations are 

primarily used for voice communication. The use of 700 MHz spectrum for public 

safety applications is attractive because of its propagation and penetration 

characteristics.

 

7 http://transition.fcc.gov/Daily_Releases/Daily_Business/2011/db0713/FCC-11-

107A1.pdf
7

In 2003, the FCC allocated 50 MHz of spectrum (4940-4990 MHz) to public 

safety8

. The FCC part 90 Rules governing the use of 4.9 GHz spectrum authorize 

public safety agencies to license and use the spectrum [472 U.S.C. §90] and the 

relationship of this band and the 700 MHz band for public safety remains an open 

question9

. Any system design should take into account the possibility of devices 

operating in distinct and even multiple frequency bands, leading to the implication 

that bridging of frequencies through gateway methods (e.g. RF, IP or application 

layer conversions) may prove beneficial.

In this essay, it is assumed that solutions to public safety communication needs 

might be augmented through the use of unlicensed spectrum in the 2.4 GHz and 

5 GHz ranges, Television White Space and even through use of 60-100 GHz 

allocations that might also be treated as unlicensed spectrum or, perhaps, 

shared for public safety and commercial purposes. These super-high-frequency 

bands have the potential for extremely high speed and broad bandwidth, 

although their propagation characteristics would likely require some forms of 

relay to achieve coverage, either owing to signal dissipation or inability to 

penetrate structures. Recently reported results10 show that these super-highfrequency signals need not be strictly line-of-sight. The potential for multiple 

small antennas to improve received signal-to-noise ratio is attractive. 

The Wireless Innovation Forum conducted two analyses of the role of softwaredefined radio and cognitive radio technology in the concept of a shared publicprivate 700 MHz network during the initial D-Block auction.11

1.9 The Role of Wired Communication

While much attention is often placed on the wireless elements of public safety 

communication, it would be a mistake to ignore or downplay the importance of 

 

8 http://transition.fcc.gov/Bureaus/Wireless/News_Releases/2002/nrwl0202.html

9 Federal Communications Commission, 3rd Report & Order and 4th Notice of 

Proposed Rulemaking Implementing a Nationwide, Broadband, Interoperable 

Public Safety Network in the 700 MHz Band (FCC 11-6), 26 January 2011.

10 Marconi Society annual symposium on communications, UC San Diego, 

September 8, 2011.

11 Considerations and Recommendations for Software Defined Radio 

Technologies for the 700 MHz Public/Private Partnership, 7 December 2007

[http://groups.winnforum.org/d/do/1579]; and Utilization of Software Defined 

Radio Technology for the 700 MHz Public/Private Partnership, 18 June 2008 

[http://groups.winnforum.org/d/do/1564].
8

backhaul and national scale broadband wired networks that bind the wireless 

systems into a national and even a global fabric. The possibilities of shared and 

variable capacity facilities used by commercial and incident responders should 

not be overlooked. Expansion of shared or sharable capacity may prove to be 

more cost-effective than separate build-outs for public safety and commercial 

systems as long as the priority of public safety needs can be assured. It has 

been observed that backhaul capacity for commercial mobile systems such as 

2G, 3G, 4G and LTE may be significantly under-provisioned and investment in 

this capacity may prove critical to the success of the national public safety 

network. 

2.0 Desirable Features of a Public Safety Network Design and System

2.1 Flexible System Architecture

Among the problems encountered in interjurisdictional public safety response 

deployments is the failure of many devices to interoperate. Even those that 

purport to implement the P25 standards12 do not always interwork. Given that 

there is a serious desire and need to support voice, video and data exchanges in 

public safety contexts, it may be instructive to consider how the Internet 

architecture supports mixed media and bridges otherwise incompatible physical 

and logical transmission mechanisms. 

An important feature of the public safety network architecture should be its ability 

to evolve. It should be able to take advantage of commercial technology and 

services but not be limited by them. Integration of multiple radios or softwaredefined radios into the system may permit introduction of new functionality while 

retaining compatibility with earlier components. 

One can also imagine the use of packet encapsulation and encryption methods 

to extend the reach of a secured public safety network across commercial 

backbones to increase the scope and resilience of the system. 

2.1.1 Use of Internet Protocols

From the NRC report on wireless technology, we read:

“Technological capabilities are also driving the introduction of new radio system 

architectures, including a shift away from centralized systems to more localized 

 

12 PSCR Compliance Assessment Program: 

http://www.pscr.gov/projects/lmr/p25_cap/p25_cap.php
9

transmission in distributed systems that use very small cells (the smallest of 

those being deployed today are called femtocells) or mesh networks, and a shift 

from centralized switching to more distributed, often Internet-Protocol-based 

networks.”13

In the Internet, a key protocol layer is the so-called Internet Protocol (IP) layer. 

This layer carries formatted “packets” of information from an addressed source to 

an addressed destination. There are also notions such as “multi-cast” and 

“broadcast” incorporated into the architecture. Internet packets are not aware of 

how they are carried. Consequenly, the routers that forward traffic from a source 

to a destination through intermediate relays may shift from one medium to 

another with impunity. An Internet packet may flow over a coaxial cable, a 

satellite link, a ground mobile radio link, and hard-wired optical fiber or Digital 

Subscriber Loop. The routers of the Internet take care of relaying packets on 

various media through the use of “convergence layer” software that adapts 

packet transmission to the next medium of transport. 

In addition, the packets of the Internet are unaware of their contents. They carry 

“bags of bits” from source to destination where the bits are then received and 

interpreted by software at the destination. The Internet is, essentially, application 

unaware and a result of this is that new applications can be added to the system 

without having to change the network. This is not exactly correct, since some 

applications would not work unless the underlying network had sufficient capacity 

(e.g. streaming video), but such bandwidth is not application specific and all 

applications potentially benefit from an increase in the bearing capacity of the 

underlying Internet.

This leads to the idea that a public safety network based on the transport of 

Internet packets might prove to be more flexible and able to bridge more 

underlying transport technologies than the present designs. Even where radios 

are not compatible, if they can be made to carry Internet packets, then an 

intermediate routing and switching device could use classical store-and-forward 

methods to receive an Internet packet on one radio transport method and 

transport in another. Such overlay methods actually animate some of the 

commercial mobile systems today and have been demonstrated in military 

tactical communication as well.14 The Internet itself makes use of the feature to 

 

13 [NRC Wireless] Op. cit. page 1

14 The Defense Advanced Research Projects Agency (DARPA) has developed a 

system called MAINGATE that has features of this kind. In addition, DARPA has 

tested ideas arising from Delay and Disruption Tolerant Networking to achieve 

robust communication in hostile, interruption-prone environments.
10

allow satellite, fiber, coaxial cable, DSL and mobile communication systems to 

interwork at the IP layer. 

On the demonstrable presumption that IP packets can carry voice, audio, video, 

and data and can be used in highly interactive modes, a public safety network 

design based on overlay transport of IP packets seems worthy of serious 

consideration. There are two formats for IP packets called IPv4 and IPv6, 

respectively. The former was standardized in 1978 and the latter in 1996. Both 

need to be supported because the IPv6 format, supporting many orders of 

magnitude more addresses, has not yet been fully deployed. 

One of the interesting features of the Internet Protocol is that it works on a peerto-peer basis. It is not necessary to pass through a router for two devices to 

exchange IP traffic assuming the devices are compatible at the layer below IP. 

This suggests that Internet-enabled public safety network radios should be able 

to exchange IP packets directly or even serve to relay such packets among edge 

devices that serve the triple role of source, sink and relay of Internet traffic. In the 

public safety network work, this is sometimes called “bypass” or “talk around,” 

although in the Internet case, virtually any class of traffic (voice, data, video) 

could be, in theory, directly exchanged or relayed.

2.1.2 Backward Compatibility

Introduction of a system that cannot interoperate with previously deployed 

equipment creates potentially serious barriers to effective operation. If backward 

compatibility requires the use of software-defined radios (SDRs), however, this 

could inflate cost. Alternatively, multiple radios within each edge device might 

actually prove to be more cost-effective. Adding compatibility modes of operation 

increases complexity, but this, too, might be ameliorated if automatic detection 

and adaptation can be achieved. A somewhat less attractive alternative is to 

make configuration relatively easier by maintaining common databases that 

associate particular edge equipment with particular emergency service/first 

responder organizations so that compatibility is achieved by configuring the edge 

equipment at time of deployment to take into account compatibility requirements.

Ideally, it is attractive to have the ability to fall back to simple voice broadcast 

without disabling the ability to use, concurrently, more sophisticated IP-oriented 

traffic exchanges. That this might involve the use of multiple radios needs to be 

considered and taken into account. Project 25-compatibility may be attractive,

although it has been noted that not all “P25” devices appear to interoperate 

directly and may require gateways to assist.

2.1.3 Mesh or Mobile Ad Hoc Networking

Even if the baseline assumption is that public safety network elements will take 

advantage of commercial LTE technology, and even if dedicated to public safety 
11

purposes, it is arguable that mesh networking could increase the flexibility of 

communication by allowing edge devices to serve as packet relays in a dynamic, 

mobile, mesh network design. The military has had considerable experience 

using these methods for tactical communication in hostile conditions. Moreover, 

these techniques may allow the use of much higher frequency and higher 

bandwidth capacities. There are commercial systems that make use of this 

technology such as the ArchRock sensor network,

15 though at modest data rates. 

The limitation of battery power is an important constraint on the design of mesh 

network protocols since every transmission draws down on the battery. Poweraware protocols may need to be developed to optimize battery life.

When combined with the ability of an Internet Protocol system to route traffic on 

alternative paths, a mesh network can be made part of a much larger, much 

more flexible, multimedia communication network. So-called “Interior Gateway 

Protocols” and “Exterior Gateway Protocols” allow for the formation of meshed 

subnets that are linked to each other through more global, internetwork protocols. 

The ability to interlink networks, to mesh adjacent, radio-compatible devices, and 

to combine them into a common network is one of the strengths of the Internet 

model and it may apply to the public safety network as well.

The introduction of dynamically deployed elements such as aerostat platforms to 

maintain wider-area connectivity to augment land-mobile communication fits well 

with a mesh kind of architecture with multilevel routing in which many networks

are interlinked, as in the internet. The same may be said for multi-radio routers 

that can re-connect otherwise incompatible land mobile networks. 

The potentially self-organizing character of mesh networks also fits well with 

cacheing or preplacement of equipment so that rapid deployment can augment, 

repair or replace damaged, broken or destroyed assets needed to support 

operational communication requirements. 

The Wireless Innovation Forum Public Safety Special Interest Group (PSSIG) 

has conducted several studies that have addressed these ideas. Two of the 

studies were detailed analyses of public safety response scenarios one actual 

(the bombing of the London underground on 7 July 2005) and one hypothetical 

(an explosion/fire at a chemical plant). In each case, the PSSIG reviewed the 

sequence of activities and postulated the impact of reconfigurable and cognitive 

radio technology on the response. For example, they identified the potential 

value of mesh-type technology in the London bombing scenario in which

responders in the underground had no connectivity with the above-ground 

 

15 ArchRock was recently acquired by Cisco Systems; see also Moog Crossbow 

[http://www.moog.com/]
12

infrastructure and resorted to running to the closest stations to relay messages. 

These reports can be found at the Wireless Innovation Forum website.16

2.1.4 Robustness and Recovery

A national public safety network must be robust and reliable on a daily basis. Its 

design must take into account power failures and loss of critical components (e.g. 

relays, cell towers, routing and switching equipment). Moreover, it must be 

possible to reconstitute the system quickly either by rapid deployment of 

replacement equipment or temporary deployment of equipment to augment the 

network operation. For example, one might imagine use of aerostats17 or balloonbased relays, repeaters, gateways and routers to provide connectivity. 

Under this rubric, it should also be an objective to make the equipment used in 

incident response as instantly available as possible. When a device is turned on, 

it should be immediately operational or as nearly so as possible. “Instant on” 

should be part of the evaluation criteria for system and device design evaluation. 

During the discussions leading to the preparation of this essay, it was observed 

that scenarios for varying levels of infrastructure loss should be developed to 

assess the ability of the public safety network to recover from and respond to 

impairments. Included in this assessment would be malicious physical and logical 

attacks, jamming and other pernicious actions intended to interfere with the 

successful operation of the public safety system. 

2.2 Security and Authentication

Public safety communications, while potentially benefiting from access to and 

use of commercial technology, equipment and services, also have a general 

requirement that use of the system and information it contains is limited to 

authorized parties. This observation does not rule out the importance of providing 

for public access information about dangers, necessary actions, evacuation 

points, shelters, emergency procedures and so on. To assure that systems 

intended for emergency responders are used only by authorized personnel, 

 

16 Use Cases for Cognitive Applications in Public Safety Communications 

Systems – Volume 1: Review of the 7 July Bombing of the London Underground, 

8 November 2007 [http://groups.winnforum.org/d/do/1565]; and Use Cases for 

Cognitive Applications in Public Safety Communications Systems – Volume 2: 

Chemical Plant Explosion Scenario, 10 February 2010 

[http://groups.winnforum.org/d/do/2325]

17 See http://www.fcc.gov/document/fcc-hold-open-commission-meetingthursday-september-22-2011
13

some form of authentication is needed not only for personal authentication but 

also to assure that the equipment tied into the system is also authorized. This is 

a nontrivial problem to solve because security and authorization can often end up 

creating unintended denial-of-service to the very parties who need access to 

respond to the emergency.

2.2.1 Strong Authentication

Since the revelation that asymmetric cryptography is not only imaginable but also 

implementable, public key cryptography has had a growing role to play in 

securing communications, effecting symmetric key distribution, assuring the 

integrity of information with digital signatures and implementing strong 

authentication of individuals and devices in networked environments. The use of 

user names and passwords, as prevalent as this has been for many decades, is 

now recognized as a risky practice subject to easy penetration in many cases. 

It is desirable to be able to configure emergency communication and information 

systems to validate the devices that access or form the networks and servers 

and also to validate users and their authorization to use these systems. Not all 

information needs to be nor should be accessible to everyone. It should be 

possible to form closed user groups for communication and information access, if 

only to limit resource demands and protect privacy and confidentiality. What is 

desired, however, is the ability to quickly and flexibly assign and restructure such 

groups as the need arises. It should be possible to predefine groups of 

users/responders who should be able to communicate. A desirable outcome is 

that communication between any pair of responders should be technically 

possible and only barred by administrative decision, not by technical 

incompatibility.

So-called “two-factor” authentication is attractive, if it can be made to work easily 

and transparently. Colloquially, this is sometimes referred to as “something you 

know and something you have.” Occasionally, it becomes “something you are 

and something you have.” The idea is that access to the public safety network 

and systems is mediated by strong cryptographic authentication. For example, a 

device that the first responder carries may contain cryptographic information that 

can be “activated” through use of a personal identification number (PIN), voice 

authentication, iris scan, or thumb print. Once activated, the device becomes the 

means by which the first responder can be remotely authenticated into the public 

safety system. The mechanics of this process can vary. One possibility is a 

“challenge/response” method in which the first responder identifies himself or 

herself with a user name and the system responds by requesting that the 

activated edge device decrypt a random numeric challenge encrypted in the 

public key of the edge device (or first responder). This random number is then reencrypted in the public key of the destination server and validated upon receipt. 
14

Methods such as this can be used to strongly authenticate devices and users as 

they enter into the public safety network. Potentially replicated and distributed 

databases can be used to confirm authorizations, exclude invalid users, and 

admit new devices into the network, etc. 

It is not the purpose of this essay to make specific technical recommendations,

but such scenarios, applied both to the users, information and the equipment in 

the public safety systems, can improve its robustness and resistance to abuse.

One can imagine devices authenticating themselves to local mesh network 

systems in order to join in radio contact and users authenticating their privileges 

through strong identification and validation of their identities. Mesh networks can 

use these methods to validate the entry of new equipment, access devices and 

servers into the system. It is important to note that pairs of devices may need to 

validate directly, possibly without reference to a third party, under some 

conditions.

These ideas are not new. Some of them can be found in the U.S. Unified 

Community Anchor Network effort.

18

2.2.2 Distributed Authentication

Because first response may involve parties from many different organizations, it 

may be important to establish the ability to validate first responders through their 

organizations, rather than attempting to maintain a centralized database of all 

valid users. Federation of the authentication system seems called for, so that a 

first responder joining a response team can be validated by reference to his or 

her “home” organization. Plainly, a trust model is needed that will accommodate 

many institutions in the same way that we trust the motor vehicle departments of 

each state in the Union to validate the holders of drivers’ licenses and accept this 

validation across the United States. There are many technical means through 

which to accomplish this federated validation and these should be investigated 

for applicability to the public safety network design.

In emergencies, the ability to qualify responders quickly to access and use public 

safety communication and information resources and to group them as needed 

for broadcast or multicast applications should be considered a highly desirable 

property.

 

18 http://www.usucan.org/
15

An example of effort in this dimension is found in the InCommon Federation for 

nongovernmental organizations whose work might be made to interwork in some 

federated way with governmental authentication.19

2.3 Standards Application and/or Development

In the Smart Grid program, the National Institute of Standards and Technology 

(NIST) instituted the creation of the Smart Grid Interoperability Panel (SGIP) that 

was populated with representatives from 22 sectors at interest in the Smart Grid. 

A Governing Board was elected from among the 1700+ participates and 656 

companies. SGIP is not a government advisory body. It is a distinct nongovernmental and non-profit organization devoted to facilitation of the 

development of standards in aid of Smart Grid development and deployment.

One could imagine a similar Public Safety Interoperability Panel operating in a 

similar fashion to coordinate the efforts and interests of the many stakeholders in 

the public safety arena. Its purpose would be to facilitate standards development 

and adoption through recognized Standards Development Organizations. While 

the SGIP effort is still a work in progress, it has been an effective mechanism for 

serious work on the elaboration of standards and requirements and identification 

of useful specifications for Smart Grid devices. There exist organizations with 

charters related to this idea such as the National Public Safety 

Telecommunications Council20 and the Federal Partnership for Interoperable 

Communications.

21

There can be little debate that standards will be a determining factor in the 

success of a national public safety network on the grounds that compatibility 

among the network elements and between and among the edge devices can only 

be usefully achieved through adoption of common standards and practices. Just 

as important as standards are tests that can verify and validate the conformance 

of fielded systems to standards. This was a crucial element in the Smart Grid 

program, and a focused working group was created to assure that this idea 

received persistent attention. The public safety network, as conceived in this 

report, is vitally dependent on consistent interoperability of all components. 

It is also relevant to note the remarkable effect of standardized,or at least publicly 

available Application Programming Interfaces (APIs) for smart phones. The large 

and growing “app stores” for mobiles have leveraged these specifications by 

 

19 http://www.incommonfederation.org/

20 http://www.npstc.org/

21 http://www.dhs.gov/files/committees/gc_1176496203797.shtm
16

allowing virtually anyone to create and make available new applications for smart 

phone platforms. A similar standardization for public safety systems could unlock 

substantial innovation from the first responder community itself. A similar 

experience can be seen in the use of information system APIs for geographic 

presentations services such as Google Earth, Microsoft Bing Maps, etc. These 

systems allow users to present their information to users and are often used in 

emergency situations to illustrate the boundaries of fires, the locations of 

emergency evacuation centers, before/after imagery in earthquakes and 

tsunamis, and so on. The application space appears to be unlimited and the use 

of APIs allows even the general public to contribute content. Plainly, validation of 

public content is important to avoid deliberate misrepresentations. It is interesting 

to note how quickly the use of mobile images and video uploaded to the 

YouTube system have been used in emergency communications by the public 

news broadcasters.

2.4 Ruggedization

While not all devices employed in the conduct of public safety service need to be 

ruggedized, some most definitely need this feature. A key difference between an 

inexpensive cell phone and a public safety radio is that there are serious 

consequences if the public safety device is dropped, submerged in water or 

otherwise rendered inoperable. For a policeman in a life-threatening situation or 

a fireman battling a fire in a wet, smoky environment, the consequences of 

mechanical or other failure can be deadly. Two conclusions may be drawn from 

this observation: 

1) ruggedized units and more conventional devices need to share architectural 

and technical characteristics that allow them to interoperate, and

2) ruggedization will have an impact on affordability, battery life, weight/size, 

utility while wearing protective clothing, including gloves, etc. 

A balance has to be struck in designing in ruggedness to assure utility and 

reasonable cost without loss of reliability.

2.5 Sensor and Location Systems

Sensors are getting smaller and proliferating and they can be effectively outfitted 

with the ability to become part of a network. That the information from such 

devices can be essential to effective incident response must be acknowledged 

and accounted for in a system designed to bring relevant data to the attention of 

responders. In essence, responders should be in a position to draw upon a wide 

range of accumulated and real-time sensor data, preferably with convenient and 

reasonably uniform user interfaces. 
17

It is vital to know where responders are, and a number of options could be 

incorporated into the design including the use GPS coordinates, and relative 

locations based on radio triangulation, among others. Commercial use of WiFi 

locations information might well prove useful in incident response to augment 

other methods, for example. Incorporation of an accurate “terrestrial GPS” 

capability in the public safety network design to better support indoor and 

underground positioning information would be very beneficial. The safety of the 

responders would be enhanced, as would the ability to locate survivors found by 

first responders, even when satellite GPS is not available. 

2.6 High Density Radio Operation

One of the classic problems that can be encountered during emergencies is 

congestion of publicly accessible wireless services, including commercial 

consumer mobile services, citizen’s band radios and, potentially, frequencies 

dedicated to public safety communications. The use of LTE, even if in 

frequencies dedicated to emergency services, might encounter congestion and 

the need for prioritization. This is equally true of packet switched systems 

operating in broadcast mode. Any successful architecture will need to deal with 

the possibility of self-interference owing to heavy concentration of emergency 

service actors in a localized region. 

2.7 Next Generation 911 Emergency Services IP Networks22

The 911 system, based on conventional telephone services, is due for a serious 

upgrade to take advantage of new communications and information technology. 

The need for standardization in such a system should be obvious. Because so 

many new platforms have the ability to interact with both the existing public 

switched telephone network (including wireless) and the public Internet, it seems 

clear that effort is needed to incorporate the advanced thinking about emergency 

services communication into the general fabric of the national public safety 

network design. There are remarkable opportunities to make an advanced 911 

system far more effective. Internet-capable devices can know exactly where they 

are, and some concepts include interior positions. For example, a hotel room 

could literally tell a mobile or laptop exactly what room it is in so that the 

emergency responders have far more than an address to go to. One can even 

imagine mobile devices that can deliver information about the condition of the 

person in need of emergency assistance thanks to various kinds of monitoring 

that is increasingly possible with smart phones and assistive devices. 

Several IP-based networks have been or are being developed to link Public 

Safety Access Points but it is not clear how coordinated these efforts have been 

 

22 http://en.wikipedia.org/wiki/Next_Generation_9-1-1
18

with regard to technical interfaces, if any, such as to the public Internet and to 

each other. This is an area well worth examining. 

3.0 Prototyping, Collaboration and Testing

The current public safety system in the United States is a diverse conglomeration 

of institutions, organizations, groups, equipment, systems, radio frequencies and 

communication protocols. Communications technology, software and systems 

continue to evolve at a rapid pace in the commercial sector as well as in the 

military and in specialized public safety sectors. Achieving long-term resilience, 

robustness, reliability and interoperability in a secure context that is flexible and 

adaptable to changing needs is a major challenge. It is a thesis of this essay that 

a purely top-down design approach is unlikely to result in a system with the 

quality and features desired and needed. Rather, serious prototyping and testing 

under realistic conditions and with the full range of public safety practitioners is 

necessary to accommodate iterative designs and maintain interoperability.

There are numerous test beds that have been organized to improve the quality of 

design and feedback for complex communications and information systems. 

Among these is the Network Integration Evaluation (NIE) effort organized at Ft. 

Bliss by the U.S. Army in cooperation with the Defense Advanced Research 

Projects Agency (DARPA).

23 Strongly supported by the Vice Chief of Staff of the 

Army, GEN Peter Chiarelli, this is a good example of the use of realistic testbeds 

to inform and drive design, innovation and validation of systems. NIST operates a 

test bed in its Boulder, CO, facility in which many first responder participants are 

evaluating equipment and systems for their interoperability and serviceability. 

It seems important to establish a framework in which implementations of first 

response support systems can be validated in realistic settings, including ability 

to support desired applications, and ability to interoperate and accommodate the 

many different organizations that have to come together to preserve public 

safety. Municipal, state and Federal cooperation should be accommodated. Nor 

can this be a one-time activity. Rather, this should become the normal practice 

for the evolution of new and improved first response systems and technologies.

As the public safety system evolves, and it must evolve, the testbeds will be vital 

for exploration of new technology, methods, ideas and architectural 

enhancements. It would be a major mistake to imagine that the design of a public 

safety system is a one-time event. It will be part of a continuing evolution of 

telecommunication and information technology and will play a key role in 

facilitating that evolution.

 

23 http://www.bctmod.army.mil/news/agility.html
19

4.0 Multiple Stakeholders

There are many stakeholders in the public safety arena (cf: section 1.1). Their 

interests and established positions vary although all of them are, to first order, 

aligned in the interest of public safety. There are many public safety 

organizations, institutions, operators, regulatory agencies, private-sector 

suppliers, volunteers, legislators with budgetary responsibility and beneficiaries 

of public safety activities. Navigating through the potential thicket of competing 

interests will not be easy. The technical community can contribute strongly 

through formulation of designs and architectures that maximize the flexibility of 

the public safety network system to ingest and use new technology, spectrum, 

platforms and systems. Leadership is needed to achieve that objective and to 

take advantage of the strengths of commercial sector capability while escaping 

any limitations that would inhibit the ability of the public safety actors to carry out 

their work. 

Among the considerations derivable from the multi-stakeholder aspect of public 

safety is the observation that the stakeholders are often on different funding 

cycles and amounts. Of necessity, decisions are frequently made independently 

among the stakeholders without regard to interoperability and interconnection. 

Steps to improve the ability of stakeholders to increase the likelihood of 

compatible operation would be highly beneficial. 

5.0 Programmatic Considerations

5.1 Public Safety Network Interoperability Panel (PSIP)

With reference to sections 2.3 and 4.0, it may be very helpful and effective to 

establish a Public Safety Interoperability Panel to help facilitate the evolution of 

standards that can help to achieve the goals suggested in this essay. NIST acted 

very effectively in the creation of the Smart Grid Interoperability Panel as a 

private-sector entity, and it seems worth considering a similar entity for the 

benefit of standards for public safety systems, equipment and applications. 

Mechanisms for preparing configuration profiles and for managing identifier and 

other resources will also be needed and might be created through the PSIP.

It is clear that a rich and diverse stakeholder representation would be required to 

make useful and effective such a panel. A business model and institutional 

framework (e.g. NGO? Non-Profit? Government-sponsored entity?) will be 

needed to assure sustained operation of the PSIP.

5.2 Coordinated Research, Development and Testing

Without doubt, DARPA, the National Science Foundation, NIST and others are 

already engaged in the development or testing of technology and systems that 

can be of benefit to the first responder community. A coordinated program of 
20

research, development and testing to include private-sector, commercial 

activities could be an effective way to harness innovative energy. A 

steering/coordinating activity engaging OSTP, NSTC, NIST, DARPA, NSF, DHS, 

NIJ24along with state and local agencies and private sector public safety entities 

may provide a platform for review of research and development activities. 

Funding for this work could derive from spectrum auctions, as currently provided 

for in legislation under consideration25. An estimated $300 million has been 

identified for the multiyear development and test effort needed to perfect the 

design of a national scale public safety system.

Coordinated use of test beds to assess, validate and refine technologies, 

prototype systems and applications could be established. Exercises involving 

public safety actors across the spectrum might also be undertaken in this test 

bed context. There exists an extensive test bed available and already in use for 

this purpose at the NIST Boulder, Colo., facility. In addition, there are Defense 

Department facilities such as Ft. Huachuca and Ft. Bliss that offer potential sites 

for interoperability testing between military and civilian mobile communication 

systems. 

The creation of a private or quasi-public entity to manage the design and 

development of an evolvable public safety network might provide a framework for 

progress. 

Areas for research and development could include:

Dynamic spectrum management

Policy management

Mobile, ad hoc networks and protocols

Introduction of broadcast and multi-cast facilities into the wireless and 

wired Internet (may require new protocol developments)

Peer-to-Peer use of LTE

Strong authentication technology and systems

Platforms for public safety applications development

 

24 National Institute of Justice that acts as the R&D arm of the Department of 

Justice [http://nij.gov/]

25 http://www.politico.com/news/stories/1011/65644.html
21

Certification regimes and practices to validate safety and utility of devices 

and systems

Support for multimedia application and integrations

Tools for collaborative display, databases and geo-spatial information

Open Source Software Development26

It is clear that there is a great deal of opportunity for advanced research, tool 

development, testing regimes and coordinating activities to make a major 

difference in the development of advanced public safety systems. 

5.3 National Incident Management System (NIMS)27

NIMS “provides a systematic, proactive approach to guide departments and 

agencies at all levels of government, nongovernmental organizations, and the 

private sector to work seamlessly to prevent, protect against, respond to, recover 

from, and mitigate the effects of incidents, regardless of cause, size, location or 

complexity.”28 NIMS provides a consistent set of policies and procedures for 

multiple agencies to collaborate in preparing for and responding to an incident. 

These policies and procedures have implications for the kinds of communication 

support needed for resource management and command in an incident 

response. The design of the national public safety network should take into 

account the referenced polices and procedures found in the NIMS framework.

5.4 Training and Evaluation Program

Any successful effort to create a national-scale public safety communication 

infrastructure and framework will also need to incorporate a training and 

evaluation program to assure that the diverse actors dependent on the system 

have adequate training, facilities, equipment and documentation as well as 

operational qualifications sufficient to assure success. 

 

26 http://sahanafoundation.org/ by way of example.

27 http://www.fema.gov/emergency/nims/AboutNIMS.shtm

28 Department of Homeland Security, “National Incident Management System,” 

December 2008, http://www.fema.gov/pdf/emergency/nims/NIMS_core.pdf
22

5.5 Institutional Framework

In addition to the Association of Public-Safety Communications Officials (APCO) 

and its spectrum management arm (AFC), the Public Spectrum Safety Trust 

(PSST),29 and the 3rd Generation Partnership Program (3GPP),

30 there are many 

other existing domestic and international bodies that have an interest in the 

design and operation of public safety communication systems and technologies. 

It is an open question whether an existing body or federation could be tasked 

with orchestrating the development of a U.S. new domestic public safety 

communication system, but it is clear that the process will need management, 

steering and oversight. A primary challenge in realizing the aspirations outlined in 

this essay will be the formation or adoption of an agent that can lead, manage 

and execute a program leading to the desired result. 

6. Conclusions and Recommendations

1. A Public Safety Capability organization should be selected or created 

to orchestrate the detailed design, development and coordinated 

operation of a new, national public safety communication system. It 

should include a Public Safety Interoperability Panel and resource 

management capability. 

2. The architecture of the new public safety network should:

a. Incorporate commercial technology where appropriate.

b. Extend commercial technology to achieve robustness.

c. Provide for backward compatibility or interoperability through 

standards adoption and/or development where feasible.

including interoperation with existing and new 911 systems

d. Give high priority to cost-effectiveness and affordability.

e. Take advantage of Internet and other packet-based 

technologies to support multi-media communication and 

mobile ad hoc network formation.

f. Incorporate assigned public safety spectrum and other data 

communication spectrum assignments and include 

opportunity for sharing where feasible.

g. Incorporate strong, federated authentication and other 

security technology to positively identify and authorize 

personnel and equipment permitted in the system.

h. Incorporate advanced position location capabilities, including 

indoor and underground location.

 

29 http://www.psst.org/index.jsp

30 http://www.3gpp.org/
23

i. Make extensive use of open national or international standards 

and, where appropriate, open source software.

3. The development program should include substantial opportunity for 

coordinated development and testing of protocols, systems, devices 

and practices among a wide range of actors including traditional 

emergency responders, national homeland security elements, 

military, state militia, municipal, private sector public safety 

organizations and research agencies and institutions. Nontraditional 

players, including a wide range of private sector networked 

information industry elements, should be included. 

4. Persistent and sustainable testbeds should be incorporated into the 

program in support of long-term evolution of public safety 

communication standards and technologies.

5. Above all, the system must be flexible and adaptable to new 

requirements and incorporation of new technologies and 

capabilities.

7. Acknowledgements

Visiting Committee on Advanced Technology (VCAT):

Thomas Baer, Vint Cerf, Sujeet Chand, Uma Chowdhry, Paul Fleury, Tony 

Haymet, Karen Kerr, Shaygan Kheradpir, Pradeep Khosla, Michael McRobbie, 

Roberto Padovani, Alton Romig, Darlene Solomon, Alan Taub

VCAT acknowledges with gratitude the following individuals and organizations:

Members of the President’s Committee on Science and Technology (PCAST): 

Mark Gorenberg, Craig Mundie, William Press, Maxine Savitz, Eric Schmidt

OSTP contributor: Aneesh Chopra

NIST and PSCR contributors and participants: George Arnold, David Atkinson 

[PSCR], Jason Boehm, Jeff Bratcher [PSCR], David Cypher, Donna Dodson, 

Cita Furlani, Patrick Gallagher, Katharine Gebbie, Ajit Jillavenkatesa, Suzanne 

Lightman, Doug Montgomery, Emil Olbrich [PSCR], Dereck Orr [PSCR], Alan 

Pentz [PSCR], Jim Schufrieder, Chuck Romine, Mark Stolorow

DARPA contributors: Kaigham Gabriel, Larry Stotts

Public sector contributors: David Boyd [DHS], Keith Bryars [FBI], Ralph Burnett 

[DHS], Andrew Clegg, Jeff Dulin [Charlotte NC Fire Dept.], Emily Early [DHS], 

Chris Essid [DHS], Anna Gomez [NTIA], Terry Hall [APCO], Regina Harrison 

[NTIA], Jim Hassett [NYPD], Joe Heaps [DOJ], Farnam Jahanian [NSF], Lance 

Johnson [NTIA], Rick Kaplan, John Leibovitz, Peter Levin, Tim Lowenstein 

[National Association of Counties], Cuong Luu [DHS], Gary McCarraher [Franklin 
24

MA Fire Dept.], Harlan McEwen, John Melvin [Grant County Sheriff], Dick Mirgon 

[APCO], Chris Moore [San Jose Police Dept.], Jon Olson [Wake County EMS], 

Craig Peters, Dusty Rhodes [DHS], Allan Sadowski [NC State Highway Patrol], 

Bill Schrier [City of Seattle], Robert Schneider, Henning Schulzrinne [FCC], Doug 

Sicker [NTIA], Tom Sorley [City of Houston], Lawrence Strickling [NTIA], Steven 

VanRoekel [OMB]

Private sector contributors: Doug Aiken [NPSTC], Coleman Bazelon, Stacy Black 

[AT&T], Vanu Bose [Vanu Inc], Don Brittingham [Verizon Wireless], Jim Bugel 

[AT&T], Michael Calabrese, Ken Carlberg, Robin Chase, John Cracolici [Cisco], 

Fred Frantz [L3 Communications], Kevin Gifford [Univ. Colorado], John 

Gustafson, Christopher Guttman-McCabe, Philip Harris, Dale Hatfield, Ajit 

Kahaduwe [Nokia Siemens], Brian Kassa [Nokia Siemens], Michael Katz, Paul 

Kolodzy, William Lehr, David Liddle , Bill Manke [Qualcomm], Michael Marcus, 

Preston Marshall [USC-ISI], Dennis Martinez [Harris], Mark McHenry, Milo Medin 

[Google], Sascha Meinrath [New America Foundation], Joseph Mitola, Michael 

Nelson [Georgetown University], Stagg Newman, Eli Noam [Columbia 

University], John Powell [NPSTC], Justin Ratner [Microsoft], Dan Reed, David P. 

Reed [MIT], Jeffrey Reed, Corey Reynolds [Corner Alliance], Dennis Roberson, 

Brian Rosen, Gregory Rosston, Andy Seybold, Bill Smith [PayPal], Darlene 

Solomon [Agilent], Saul Steinberg [Motorola], Marilyn Ward [NPSTC], Tony 

Werner, Diane Wesche [Verizon Wireless], Tony Wheeler
25

References

[MAINGATE] http://www.afcea.org/signal/articles/anmviewer.asp?a=2102

[NFPSBBN] National Forum on Public Safety Broadband Needs 

http://www.cops.usdoj.gov/RIC/ResourceDetail.aspx?RID=601

[NRC Wireless] Wireless Technology Prospects and Policy Options,

National Research Council, 2011, National Academies Press,

ISBN-13: 978-0-309-16398-9, ISBN-10: 0-309-16398-6 [more stuff goes here]

Glossary

3GPP: 3rd Generation Partnership Program [http://www.3gpp.org/]

AFC: APCO Spectrum Management [http://www.apco911.org/frequency/]

APCO: Association of Public Safety Officials [http://www.apco911.org/]

COPS: Community Oriented Policing Services [http://www.cops.usdoj.gov/]

IP: Internet Protocol

LTE: Long Term Evolution [refers to long term generations of commercial mobile 

radio]

NIMS: National Incident Management System

NPSTC: National Public Safety Telecommunications Council 

[http://www.npstc.org/]

PSCR: Public Safety Communications Research (NTIA/NIST)

[http://www.pscr.gov/]

PSIP: Public Safety Interoperability Panel [an idea introduced in this essay]

PSST: Public Safety Spectrum Trust [http://www.psst.org/index.jsp]