DoD is working toward increasing the number of battlefield sensors deployed across the battlefield to be the eyes and ears of distributed operations. Ultimately, their effectiveness will depend on development of large-scale networks dedicated to conveying their data to commanders.

The military sensor community is increasingly involved in establishing requirements for, and in some cases acquiring, the networks to transport the data they generate. Army Colonel Glen Lambkin, program manager for night vision/reconnaissance surveillance and target acquisition (PM NV RSTA), is responsible for a range of systems that run the gamut from counter-fire radar to unmanned sensors to infra-red systems in both an air and ground, supplying them to the Army and other services.

“One of the revolutions that have occurred is the significant use of video to prosecute the war, as opposed to more traditional message-based C2,” Lambkin commented. “We have to work very carefully and develop video management technologies and integrate video smartly, because communications bandwidth is highly restricted. For that, we have to depend on technology advances that enable us to integrate sensor information and then transmit that information efficiently over constricted communications pipelines.”

“We look not only to the sensor’s performance, but also communications requirements to best capitalize on a networked and integrated sensor solution. For the current and immediate near term, many of our communications requirements are driven by operational needs, which are generated in theater, sent through CENTCOM and then to either OSD staff or the services. For longer-term systems, we are integrating those technologies and sensors into our formal programs of record, so that they have life beyond the current operational needs statement,” Lambkin said.

Cooperating with others on shared needs is a feature of current development work. PM NV RSTA works closely with Army CECOM, Program Executive Office Command, Control, Communications Tactical, and TRADOC on identifying requirements for sensor networking. More recently, efforts have been stepped up by TRADOC in working more closely with the Army Signals Center and in conjunction with Fort Huachuca, Ariz., which has responsibility and proponency for many of the Army’s intelligence functions and sensors.

“In some cases, we are also the communications provider, in that we procure communications systems and equipment primarily for the current fight, but we do that in conjunction with TRADOC and CECOM and the warfighter communications staff,” he said. “In other cases, we rely on systems that are provided by the services and other communications programs within the Army.”

Lambkin said the community has recently stepped up work to identify long-term communication requirements and establish modeling efforts for communication paths that can be identified and programmed for the future.

Soldier Waveform

For the future force, data at the lowest level will be transported using the forthcoming Soldier Radio Waveform (SRW) developed under the SLICE program by the Army, Defense Advanced Research Projects Agency (DARPA) and ITT and hosted on Joint Tactical Radio System (JTRS) hardware. At the lowest levels, it will be hosted by the small form fit (SFF) embedded radio, which is being acquired under the General Dynamics C4 Systems-led JTRS hand-held, manpack, small form fit (HMS) program.

The SRW currently is being funded and managed by the Network Enterprise Services group within the JTRS Joint Program
Executive Office (JTRS JPEO).

Mike Lebrun, product manager for JTRS HMS program at the JTRS JPEO, outlined how sensor data is already being successfully networked using the SRW hosted in JTRS radios from both the HMS and Ground Mobile programs.

“I recently spent three days at the Ground Domain VIP demonstration at [the Army Intelligence Center and School at] Fort Huachuca. There we had had an operationally representative scenario with SFF-A supporting one of its objective platforms, the unmanned ground sensor, providing that digital link between a simulated sensor field and a GMR radio in a scout vehicle, which passed the information back to a battalion tactical operations center (TOC) and to the maneuver element in that battalion, demonstrating that the radio functions are interoperable between GMR and HMS.”

The SFF-A used the SRW version 0.5 in this demonstration, supporting digital video using the waveform’s electronic warfare mode.

The major user of SFF-A will be FCS-UGS, a two-strand program delivering the wide area surveillance Tactical-UGS (T-UGS) and the more narrowly focused Urban-UGS (U-UGS). Prime contractor Textron Defense Systems has delivered an early UGS capability for testing, consistent with the FCS program vision to spiral-out FCS technology as it evolves. Ten T-UGS systems, equating to 130 nodes, and 16 U-UGS systems, equating to 272 nodes, have recently been delivered to Boeing and the Army. Integration testing is being undertaken now and the assessments will continue throughout the summer.

SFF-A’s development timeline did not match up to the program and Textron Defense Systems needed a surrogate communication system, running an interim version of the SRW, which was provided by the JTRS HMS program using ITT Sensor radios.

Once SFF-A becomes available, it will be integrated in to the UGS nodes for the planned fielding, potentially in 2010.

Dean Frost, chief engineer for UGS at Textron Defense Systems explained that for FCS UGS, distributing data within the UGS field is a critical first step in developing information that can be exported to higher echelon networks. “We share that data between sensors, which gives us better performance and offers an important distinction from current force stovepiped systems. Sharing multimodality sensor data, such as seismic, acoustic and infrared imaging, among sensors allows precision, simultaneous tracking and counting, and does so over much larger areas. This provides a greater situational understanding with significantly higher fidelity and the ability to feed that up the network to exploit other net-centric features.”

“We have a requirement to utilize the JTRS communications system to maintain interoperability with the higher level FCS network,” explained Dave Scaringella, program manager for FCS UGS at Textron. “Therefore the sensors and the algorithms were adapted to accommodate that communications solution. We have taken significant measures to incorporate state-of-the-art image compression algorithms to minimize the bandwidth consumption, which allows us to still get the full benefits of motion imaging back to the warfighter.”

Urban and Tactical UGS use slightly different networks. “Both have two tiered, independent layered networks—a short haul network and long haul network. The long haul network will be the same for both urban and tactical from a hardware and network perspective using the HMS SFF-A, giving the same interoperability and protocols with the FCS network,” Frost said.

Because of particularly tight size, weight and power constraints, a different approach has been adopted for the U-UGS Short Haul network, Frost said. “In the case of Urban UGS, we have taken commercial Honeywell embedded radios, and added security features and information assurance provisions needed for military systems. You still get ad hoc self-forming networking on both networks, which allows scalability to adapt to a wide range of mission requirements.”

ITT’s military-off-the-shelf solution for sensor networks is the Sensor Radio, noted Larry Williams, director of business development at ITT. He explained that a common theme in providing communications for UGS in general is that they must be expendable due to an inherent susceptibility to loss and capture. This prompts certain approaches to cost and information assurance

“The Sensor Radio is currently in security testing, getting certified and will be available for purchase and application to additional products shortly. This is not an NSA-certified Type 1 product,” said Williams. “Because they’re basically disposable, they will have NIST FIPS-140-2, type certification.”

ITT has worked with Textron in support of FCS experiments, and has used a 225-450 Soldier Level Integrated Communications Environment (SLICE) 2.1 waveform in support of the FCS spin out process. The Sensor Radio could use the SRW in the future when this is finalized and is made available. “UGS is the primary market for the Sensor Radio, but we have also tested it with several commercial sensors of the UGS type with video and data. We are working with several companies on that,” said Williams.

The Sensor Radio is just under 10 cubic inches and weighs less than half a pound. Within that envelope, users get data rates of 56 kbps at a range of 3 km or 225 Kbps at 400 m from a 1 W output power with a self-forming, self-healing ad hoc network.

Ground Layer

A further transformation involves using communications networks hitherto limited to connecting airborne ISR networks to converge communications at the ground mobile layer.

L-3 took a range of its sensor networking technology to PM C4ISR OTM Experiment 2007, held over a two-month period last summer. This system of systems exercise/experiment evaluated a large number of Army-defined operational threads. It involved fixed and mobile terrestrial platforms, mounted and dismounted soldiers, UGS, airborne platforms and access to space assets. The experiment was designed to evaluate current and emerging technologies in realistic scenarios to see how well they improve overall mission effectiveness for the warfighter.

The component that L-3 provided in the experiment was the high-capacity backbone network, overlaid on other tactical networks that were part of the experiment. These included Tactical Common Data Link terminals, each providing up to 45 Mbps of full duplex connectivity across the various elements. Each terminal provided IP transport services for all types of data generated at the experiment, including ISR sensor data, FBCB2, and battle command data.

“What is important about these terminals is their small size and high user data throughput,” said Steve Barham, director, advanced programs, L-3 Communication Systems-West. “That capability has historically been utilized by the ISR community on dedicated platforms like Global Hawk, Predator and Guardrail. By miniaturizing terminal sizes and employing IP, that same technology can now be exploited for use by tactical units. This technology provides about 30 times the overall network capacity that is available today to the current force. It also offers advantages of extended reach and joint interoperability, since it’s based on DoD and commercial standards.”

The smallest TCDL terminal employed at the exercise weighed less than 2 pounds. It was flown on a representative UAV indicative of the Future Combat Systems Class 1 UAS. “That was a prototype terminal matured to TRL 7,” said Barham. “We are in the process of productizing it and there are a number of programs of record that have either placed orders or are planning to use that technology.”

During the demonstration, other TCDL terminals were employed that are widely utilized across the services at a TRL 9 maturity level. These terminals flew on an aerostat and on an ERMP surrogate fixed-wing aircraft, and were installed in fixed and mobile surface installations. They also provided up to 45 Mbps full duplex capability, and a fully capable layer 3 IP router. The router currently supports IPV4, and is being upgraded to support IPv6.

Regarding the router, Barham said, “We successfully demonstrated the use of IP as the common convergence layer. We took data that was transported across Army tactical networks and other data links, and interfaced those links directly with our IP router Ethernet interface. This allowed the Army to send large amounts of IP data over long distances using the TCDL terminals as the high-capacity backbone.”

“Our routers are noteworthy because they are programmable—analogous to software-defined radios, so we can change and adapt to different situations and different circumstances that might be presented to us. Our routers are also highly ruggedized. We can put routers in unattended ground scenarios, rugged mobile vehicles, or in pods on tactical fighters.”

The routers used are developed with commercial OEM technology, so that they are fully interoperable with commercial routers and infrastructures.

IP Convergence

Convergence using IP was shown working with the Army’s SRW network, and with standard applications such as FBCB2 (Force XXI Battle Command, Brigade and Below). These messages were transported over the backbone from dismounted and mounted soldiers to and from the TOC through the TCDL high capacity backbone.

In subsequent experiments, “We have also interfaced with other terminals such as Link 16 and HNW,” said Barham. “Anything that is transporting IP packets and can interface over Ethernet using a standard router can connect into this high-capacity backbone.

“In the past, we have had two different infrastructures, ISR infrastructure and the ground tactical infrastructure. We demonstrated that using IP as a common convergence later, it doesn’t really matter what data you send over the infrastructure. You can now have a common infrastructure that has very long range and very high capacity to send any kind of data you want, whether it be ISR intelligence-related or battle command-related, and it is a very efficient use of resources,” he continued.

Also used were L-3’s ROVER receive-only terminals, currently operated by deployed forces to display ISR data from virtually any airborne sensor platform. These key elements were adapted and IP enabled, and employed by mounted and dismounted users.

“The ROVER supports multiple frequency bands, so it can access sensors data in real time, from virtually any sensors, using analog or digital communications,” said Barham. “ROVER is used across the services, and is a key component in the Army’s OSRVT system. With ROVER you have the ability to provide real-time video to soldiers in the field for close air support and other time-sensitive operations.

“Soldiers on the ground using ROVER were able to receive sensor data from several different sources, including Class 1 UAVs, fixed-wing aircraft and other platforms,” Barham said. “That is what ROVER does today operationally. What the experiment examined took that further by assessing the benefit of taking this sensor information and distributing it over other IP-based networks.

“We were able to distribute sensor data from ROVERs to other dismounted soldiers using the SRW network, into the WIN-T network through our wideband Phoenix SATCOM terminal, and back to the TOC for analysis through an airborne relay using the TCDL high-capacity backbone,” he added. “It allowed the sensor information to be used within milliseconds by the soldier in the field, but also disseminated to other dismounted soldiers or to the TOC or anywhere else that was connected to the network in real time over long range.”

Outside that project, the company is demonstrating that sensor data is no longer reliant on the communications network, but actually becomes part of it. The TCDL terminals are software definable and have operated with a variety of antennas. In tests, this has included connections to electronically scanned, phased radars from a number of manufacturers. The same radar aperture antenna used to collect data is then used to transmit high-rate digital data.

“We provide the software-definable modem, which interfaces with the radar and adds the communications capability. These modems are IP enabled and are software programmable so they can interface with a wide variety of different apertures, different waveforms, and interface characteristics at very high data rates without requiring the addition an antenna dedicated to high-rate communications,” Barham said.

Inter-Node Communications

DARPA’s information exploitation office has made significant investments in exploring how large sensor networks can be made and providing the underlying technology, including communications to support massive increases in the number of sensors.

A key tenet of one such program is to utilize the same waveforms and perhaps energy for sensing and inter-node communications. Two waveforms are currently being investigated to meet these requirements: an ultra-wideband (UWB) and a frequency-hopping waveform. In both cases, a time-division multiple access (TDMA) schedule is utilized to manage interference and wake-up cycles. In general, Camouflaged Long-Endurance Nano-Sensors (CLENS) communications bandwidth requirements are quite modest, as the sensor data is processed within the node with only target reports communicated.

“No attempt is being made for the inter-node communications to be compatible with current and emerging Soldier Radio Waveforms—waveform and band selection are dictated by the sensor (radar) requirements; communications is secondary,” a DARPA official explained. “The CLENS network would be interfaced to a user-specific gateway by connecting a standard CLENS node directly to the gateway. Interoperability with other military communications systems can be achieved through this gateway approach.”

The agency’s Networked Embedded Systems Technology (NEST) program, which concluded last year, successfully demonstrated the types of operational sensor numbers indicative of next generation networks using over 2,200 simple computing nodes. In doing so, the program identified and resolved critical scalability issues with the software, which now makes it possible to support tens of thousands of nodes.

Based on these results, DARPA believes it is possible to scale to 100,000 nodes using the NEST software. To illustrate, a DARPA concept video shows troops entering a city with thousands of NEST sensors, dropped like confetti over the area by UAVs and used for sniper detection, wide area surveillance and monitoring and critical asset protection

Barriers to near-term realization remain in the area of micro-sensor hardware. For example, the normally simple tasks of installing/replacing batteries and turning on power switches becomes impractical with a large number of nodes. DARPA continues to invest in advancing the state-of-the-art in low-power, micro-electronics technology. It is estimated that an improvement of at least an order of magnitude over current power consumption levels is needed to realize the goal of a large, persistent network, defined as six months or longer network of micro-sensors.

The DARPA official commented that, if scalability is to be achieved, micro-sensor networks must be self-coordinating, requiring a similarly revolutionary improvement in sensor networks. The official added that NEST had already demonstrated a degree of “macro-coordination” of sensor fields using existing military command and control assets.

NEST began in 2001, sponsoring research in academia, and transitioned to industry in 2005 with industry partners that included Raytheon and Puritan Research.