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COMM-OPS: UAV Cellular Payload for First Responder Emergency Teams
by Robert Varga, Ph.D.

As National Guard, fire, police and other military and civil first responders begin to stabilize a region in the wake of a natural or manmade disaster, they face challenges in coordinating their efforts using standard UHF or VHF radio communications. Reacting to these challenges during the 2007 wildfires in southern California, enterprising first responder groups successfully used their personal cell phones to improve communications interoperability.

What if we could expand on this germ of an idea, leveraging the power of 3G wireless devices to include not just voice, but imagery, location, and other data? The resulting system could provide responder teams and commanders with critical multimedia, street level imagery, or even biometrics for identification or medical status, significantly improving situation awareness and a common operational picture with maps and coordinates of personnel, victims, and threats.
Enerdyne Figure 1

The capabilities of 3G systems, and the portent that 4G network bandwidth will rival cable and DSL performance, strongly suggests that smart cellular phones — which continue to get smarter by the day — are potential disruptive alternatives to legacy UHF and VHF radios. The only limiting factor to this alternative might be the sheer scale of some disasters. For example, hurricane Katrina wiped out the cellular infrastructure over large areas of southern Louisiana and Mississippi. And in the aftermath of the 9/11 attacks in New York, cellular networks were saturated with excess demand, all but eliminating reliable communications.

Paradise Ad MSM JulAug09 One recent example shows this idea’s potential. Within a few days after Katrina moved through the Gulf States, a group of ViaSat and Qualcomm personnel airlifted portable equipment to provide a localized, private cellular “bubble” for first responder teams. Figure 1 shows how a Qualcomm mobile CDMA system, consisting of transit cases containing a picocell base station and a media switch, was placed on an office building roof in downtown New Orleans. Pre-registered Nokia handsets were distributed to a few key officials, and Verizon granted permission to use its frequencies since its service was knocked out by the extensive hurricane damage.

This private cellular network allowed communications between any pair of handsets that were registered to the network and located within the range of the picocell transceiver. And for calls outside the network, a ViaSat IP Satcom Flyaway Terminal acted as a gateway to the PSTN. Outbound calls were routed from the base station through the media switch to the flyaway terminal and transmitted via satellite to a ground station at ViaSat headquarters in Carlsbad, California, where a physical connection was made to the PSTN.

This ad hoc exercise clearly demonstrated the viability of establishing emergency, rapid-response, private 3G cellular communications. However there are limitations to the system, including the coverage radius, which was bounded by the height of the base station transceiver, its RF power amplifier, and RF antenna pattern. The tallest office building in New Orleans, at 51 stories, would provide a potential coverage diameter of only about two to three miles. Emergency communication planners can’t afford to make assumptions about the proximity of a sufficiently high vertical structure, nor its access, its safety, or the safety of the surrounding environment

This article expands on this private cellular network idea by placing the picocell base station components at altitude using an unmanned aerial vehicle (UAV). Flying at several thousand feet or higher significantly improves the coverage area and eliminates any dependency on ground structures. In a context of first responder emergency communication needs, the article describes a baseline system configuration, system performance, and applications that could support mission execution and provide high fidelity situation awareness for first responders and their commanders.

Moving To Altitude Expands The Private Cellular Bubble
The core cellular network includes a small light weight 3G CDMA base station transceiver and controller that would support three sectors and up to 50 cellular handsets per sector. A choice favoring either 1xRTT or EVDO technology will depend on whether voice quality or data throughput is more important. Although 1xRTT is capable of higher data rates, most deployments are limited to a peak of 144 kbps. Packet-based EVDO provides end-to-end IP support for both voice and data, with a forward link peak of 3.1 Mbps and a reverse link rate to 1.8 Mbps. EVDO was designed for end-to-end operation as an IP-based network, so it can support any application made to operate on such a network. Both operate within 1.25 MHz channels.
Enerdyne Figure 2

This CDMA equipment is sufficient to define a completely functional cellular network. It can be configured to openly allow access by any CDMA device or restricted to allow communications only among those devices pre-registered within the network. Flown at 3,000 feet with a 5 watt power amplifier, the base station transceiver, PA, and antenna would expand the communications bubble to approximately 13 miles in diameter. At an altitude of 5,000 feet the diameter expands to 20 miles. Figure 2 illustrates a UAV loitering over New York City. At these altitudes, and with a modest sized power amplifier, the signal strength should be excellent.

The Qualcomm mobile picocell system used in New Orleans has been successfully flight tested in C-130 and other aircraft. Northrop Grumman has added this capability to its Battlefield Aircraft Communications Node (BACN). This equipment could possibly fly on the largest UAV platforms, such as Global Hawk, which may have the payload capacity to handle the power, size, and weight of this system.

Tactical UAVs Are A Better Choice To Carry The Cellular Payload
Yet the case is much stronger for using a “tactical” unmanned aerial vehicle, much smaller than the Global Hawk, including a much lower cost of operation, lower cost payload, on site duration, launch readiness, flight control, and ability of lower echelon military personnel to carry out such a mission. A model UAV for cellular payload is the AAI Corporation Shadow. This platform is a proven performer, having exceeded 400,000 flight hours in service with the U.S. Army, Army National Guard, and Marine Corps. More than 90 percent of these operational hours are in support of operations Iraqi Freedom and Enduring Freedom.

Among the advantages of Shadow is that 33 Army National Guard Units are already trained and equipped with Shadow systems. In addition to the Guard’s role in the GWOT, it also has a key role as a first responder, supporting state and local authorities in the event of homeland man-made or natural disasters.

A Situation Awareness Multiplier
A year ago, more than 2,500 Air and Army National Guardsmen teamed with agencies across Iowa to battle what is now considered a 500-year flood. In addition to boots on the ground, Shadow systems could be leveraged to provide aerial video surveillance of local damage, identify threats, find stranded citizens, and monitor rescues. The addition of a cellular payload could provide a 24/7 bubble over a disaster area linking all responders and their commands with a common operational awareness.

Enerdyne Figure 3 The Shadow payload capacity of 45 pounds and power budget of 300 watts is considered substantial for this class of unmanned aircraft, but is a potential challenge for advanced electronics payloads. Nonetheless, trade studies reveal that a COTS base station transceiver, controller, and 5 watt PA from Star Solutions are well within the Shadow SWaP budget. In addition, there is adequate budget for an air-to-ground, full duplex digital data link, PA, and antennas, all discussed in detail to follow. The picocell equipment includes a choice for either 1xRTT or EVDO technology. The base station controller system can use the Windows® XP operating system, and could be ruggedized to handle UAV environmental specifications. Figure 3 shows how these components fit into the Shadow payload area.

Downlink To Command Center
One of the key first responder roles is to leverage personal training and experience to provide accurate situation awareness to peers and leaders on the ground, and to higher levels of command. This next layer of communication provides an essential connection between rescue teams and their commanders.

In the event of a disaster a command and control center is typically set up to direct personnel, allocate resources, unify efforts to aid victims, and re-establish order. There, commanders and analysts need timely, accurate information. Voice is immediate, but has transient value unless archived, and sharing voice content can be inefficient. Text messaging can provide an accurate situational description, is readily saved and shared, but seems inefficient in emergency situations. Street level still images or even video clips grabbed by smart handsets, when combined with voice and text, greatly enrich the context. Finally, when the locations of rescue personnel, disaster hotspots, or victims are forwarded and displayed on a detailed map, his is an achievement of high-fidelity situation awareness.

A contemporary smart phone can capture every one of these data types, including its own GPS coordinates, and forward them as encapsulated IP to the base station and then through an air-ground data link to the command and control station. For example, the EnerLinks®III full duplex digital data link can deliver IP traffic over L-, S- or C-band frequencies at any data rate from 50 kbps up to 11 Mbps. Consequently voice, GPS, and other IP data from the cellular handsets, can be routed through this data link to a remotely located ground station.

Designed to meet the constrained size, weight, and power of tactical UAVs, this data link system accepts TCP/IP or UDP traffic over Ethernet, as well as two channels of analog video, and six channels of serial digital data. The aircraft’s above-ground video feed significantly adds to the command center situation awareness. In fact, the H.264 compression in the EnerLinksIII, supports two full-motion high-quality video feeds and requires only 4 Mbps in total, leaving another 4-5 Mbps for cellular voice and data. At C-band (4,400 — 5,850MHz) a small “button” 4dBi omni antenna on the aircraft, and a 24-inch parabolic dish with a gain of 28 dBi, will reliably close the link at 50 to 60 nautical miles, allowing location of a command center at a convenient or safe distance from the disaster area as shown in Figure 2.

The Local “Survivability” Node
While the picocell base station transceiver and controller are sufficient to support cellular communications among 50 to 100 or more first responders, it is limited to just that capability. Adding a ground based mobile unit with a handful of optional network assets can add significant flexibility, including access to public networks.
Enerdyne Figure 4

“Survivability” means that there is no dependence on external resources to provide essential communication services. A mobile survivability node includes hardware and software resources that will provide complete self sufficiency to configure, control, and adapt network services as required:

Media Gateway (MG): An IP connectivity system that allows local, long distance, or international calls from the private cellular network into or from public telco networks, via PSTN, PBX, or satcom access. In disasters of the scale of hurricane Katrina or the 9/11 attacks on the Pentagon and World Trade Center, open communications between first responders, command centers, DHS, and FEMA leadership could only have improved decision making and response effectiveness.

Mobile Switching Center (MSC): The most important feature of this system is its administrative capability for registration and authentication of mobile users using a database server known as the Home Location Register. While a number of pre-provisioned, charged, and registered handsets could be part of a first responder “jump kit”, it would be useful to add a specific name to each handset, and update the handset address book. In the course of an emergency response, phones can be lost or damaged and additional personnel resources, authorities, etc., may be directed to support and communicate with deployed disaster response teams. Other handsets could be added to the network on an ad hoc basis.

Serial Port Server: This is an interface for support personnel to connect a terminal for access to the Survivability Node. All administrative, setup and support functions, such as adding phones, updating the configuration, and trouble shooting, can be accomplished in the field using this terminal.

Media Resource Function (MRF) Server: This server provides the tones you hear when you are making phone calls to other Survivability Node users. The tones are as basic as ring and busy tones, but can be announcements that let you know when a phone is not connected to the network.

Packet Data Service Node (PDSN): The PDSN is the server that allows the node to connect a mobile handset to the Internet. Allowing the handset to access remote or local websites can aid first responders in their ability to send and receive information.

Ethernet Switch: An Ethernet Switch within the node provides all of the IP connectivity between network elements allowing them to communicate to one another.  

Situation Awareness Increases First Responder Effectiveness
In the course of disaster relief, a first responder’s personal performance, safety, and team coordination greatly improves with knowledge of his or her surroundings. Likewise when field commanders have a comprehensive view and location of personnel, victims, equipment, resources, and physical damage, and when they can see the evolution of events, or potential threats in a Common Operational Picture (COP), they can respond more capably and in less time.

A good example of a commercially available COP for everyday use is Google Maps. This software is downloadable for free and runs on PCs, Macs, and smart phones. It has accurate street maps and can reveal building details with a satellite view. A selection of “Street View” gives rich imagery showing details of buildings and landmarks in any direction and at any location. On a cell phone your location is shown on the street map when the GPS radio is on. Directions from your location to another destination can be obtained through a text entry or graphically using the map. It is easy to imagine how much this current capability would aid a first responder in an unfamiliar urban environment.

Today, Google Maps and Google Earth are used as a framework for very complex military command control and intelligence systems. The integration of such applications with a relational data base and data mining applications can provide an extremely rich operational picture for military, government, or commercial use.

Figure 4 depicts major components of a conceptual COP for disaster relief support. The colored dots on the street map are the locations of first responders, automatically plotted from the cell phone GPS coordinates that are downlinked from the UAV. Individual names shown are obtained by correlating registration information from the phone with the MSC address book. A click on any dot gives options for reviewing archived information in the form of text, images, or video clips. There are options for calling, email, or texting. Other valuable features could include the ability to search content using a filter specified by combinations of date, time, free text, and a latitude / longitude region. Archived information retrieved from this system would be invaluable for after action reports, forensic support, and training.

An excellent example of a system that provides these capabilities and more is the patented software called LifeRing™ from AGIS Inc. This application runs in a Microsoft Windows environment and has been ported to a number of smart phones and PDAs with the Windows operating system. By pushing the COP to the mobile unit, it becomes a hand-held command, control, and communications device.

Satellite Connectivity
For disaster relief it seems paramount to connect the survivability node at the command center to the public telephone network. The first order need is basic voice contact to higher authorities. For example, the heads of DHS, FEMA, and U.S. NORTHCOM and their subordinates are likely to remain in close contact with disaster relief operations. In the current government administration, it would not be surprising if the U.S. president requested to speak directly with first responders. In addition it would be possible to provide a comprehensive near real time COP to these same authorities, in a war room environment, or on their personal handsets.

Otherwise, connection with the PSTN is achievable through a satellite link. The ViaSat IP Satcom Flyaway Terminal provides tactical deployment of broadband, network-centric satcom to any location. This rugged terminal can be set up in about ten minutes and offers two-way, IP over existing C-, Ku-, or Ka-band transponders, allowing wireless and secure connections from any location in a theater of operations or in an emergency response area. As mentioned earlier, the flyaway provided the broadband backbone for mobile communications during hurricane Katrina. A comprehensive view of the communications network appears in Figure 5.

Extensible Applications
The concept can be scalable and transportable to support military operations in remote parts of the world such as the horn of Africa or Afghanistan, which suffer from a lack of communications infrastructure. Cellular communications among U.S. or coalition forces could be activated or terminated as required by each mission.
Enerdyne Figure 5

In an entirely different operational concept, the cellular system may be used to receive and control a call from a third party that would otherwise be controlled by another cellular network. In a rural environment where the UAV is at 3,000 to 5,000 feet, the signal strength to the UAV is likely to be dominant. Control may include completing or terminating the call. In an urban environment, especially a dense one with many cellular base stations, control would be very difficult to achieve.

In the recent Gaza war, Israel and Hamas claimed to have hammered each other with threatening text messages, bringing a new dimension to psychological warfare. A loitering UAV could be used to capture opposition cellular numbers and later disseminate text messages.

Unattended ground sensors equipped with cellular technology could be monitored from a loitering UAV.

In a more peaceful application, UAVs equipped with base station equipment could be used to locate persons who may be lost, provided they have an activated handset and a GPS radio.

Network Security
In some applications network security may be essential. Several degrees of security are available. The noise-like signature of a CDMA signal, which is a 42-bit PN sequence, scrambles voice and data transmissions to make over-the-air eavesdropping very difficult.

CDMA uses the standardized CAVE (Cellular Authentication and Voice Encryption) algorithm to generate a 128-bit sub-key called the “Shared Secret Data” (SSD). An A-key is programmed into the mobile unit and is stored in the Authentication Center (AC) of the network. The A-key, the ESN (phone electronic signature number) and the network-supplied random binary number RANDSSD are the inputs to the CAVE that generate the SSD. The SSD has two parts: SSD_A (64 bit) for creating authentication signatures and SSD_B (64 bit) for generating keys to encrypt voice and signaling messages.

Blackberry offers AES encryption in conjunction with its enterprise server, which could reside in the survivability node. Another option is the General Dynamics Sectéra® Edge™ smartphone, which is an NSA-certified Type1 phone and PDA for making secure phone calls, with secure access to classified networks, e-mail, and web browsing via high-speed GSM or CDMA cellular networks worldwide.

In Support Of Loitering
The application of 3G cellular technology to support homeland defense, disaster relief, or military operations is transformational, with the clear potential to displace the use of tactical radio systems. At the handset level there is a clear confluence of high bandwidth wireless technology, computing, software applications, and multimedia. This confluence is revolutionizing a broad component of how we conduct our lives in so many areas, such as personal communications, entertainment, shared experiences, shopping, business management, and education.

There are a few nascent military R&D projects that are testing and evaluating the capabilities for private cellular networks supported with airborne base stations, but before the next generation of military leadership is in place, the use of this technology should be ubiquitous. In any case, a large-scale disaster can bring the cellular infrastructure to its knees. A loitering UAV system can recover essential capabilities and provide 24/7 coverage for disaster relief teams.

About the author
Robert Varga, PhD, is the Vice President of Marketing and Business Development for Enerdyne, a ViaSat Company
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