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Simulation Project Demonstrates Covert Applications

Researchers in the United Kingdom have completed a preliminary investigation into the use of millimeter-wave, body-worn antenna arrays to create mobile ad hoc networking for dismounted combat soldiers. The effort proved the feasibility and benefits of such a network as well as provided a platform for future study of the concept. Personnel involved in the experiments focused their work on the 60-GHz band, which offers the high amount of bandwidth necessary for troops to exchange large quantities of information on the battlefield. The short range of the communications enhances covertness by reducing the chance for enemies to exploit transmissions, and it also reduces interference.

In a recent experiment funded by the U.K. Ministry of Defence and carried out by personnel at the Centre for Secure Information Technologies, Queen’s University Belfast, researchers used simulation to test mobile ad hoc networks for dismounted troops wearing antenna arrays. This image depicts the scene and explains the actions in the scenario where troops have to leave a vehicle and secure an enemy command center.

Studies reveal potential to pass large amounts of data between troops a short distance apart.

The U.K. Ministry of Defence (MOD) sponsored the study on the antenna arrays through its former “Competition of Ideas,” which has since been superseded by another process. In addition to providing funding, the MOD also guided the technical direction of the project by informing researchers where they should focus the potential of the research and simulation. The work provided information for the ministry to provision future wireless networking technologies.

Dr. Simon Cotton and Professor William Scanlon, both from the Centre for Secure Information Technologies, Queen’s University Belfast, and Professor Bob Madahar, chief technologist, Information Management Department, Defence Science and Technology Laboratory, collaborated on the work. The main aspect of their research studied the wireless communication channels between soldiers during hypothetical, simulated battlefield operations.

In the course of the project, a number of experiments and other simulations were performed. The main simulation focused solely on a military context considered a hypothetical counterinsurgency cordon and sweep operation. It simulated a wide range of scenarios including communications between troops outside a building, troops inside the same building and troops outside the building to troops inside the structure.

According to Cotton, the study primarily was conducted using simulation and some laboratory-based point-to-point measurements. He explains that because the development of wearable 60-GHz technology is still in its infancy, it was not feasible at this stage to perform realistic experimental trials in the field. Instead, state-of-the-art animation software and electromagnetic simulation tools were leveraged to model soldier movements accurately and to perform precise channel simulations.

The simulator the researchers utilized enabled them to manipulate the soldier models through means such as adjusting posture, movement and walk paths by employing software that typically would be used to develop computer games and animations. “Wireless channel simulations were then performed using a commercial ray-launching engine,” Cotton says. “A proprietary algorithm tracked all antenna position and orientation changes throughout the exercise.”

The researchers invested a large amount of their time in building the new simulator they needed to conduct their research. “The hardware available for the frequency involved was generally quite bulky and most certainly not feasible for mounting on the soldier,” Cotton explains. In addition to surmounting the issues with wearable measurement equipment, the use of a simulation platform allowed scenarios to be readily reconfigured without the need for expensive, time-consuming field trials. This platform made an in-depth analysis of link performance possible. “Ideally, the end goal of this, and future/associated research, would be something that soldiers could strap on or integrate with their uniform,” Cotton says. He adds that the antennas most likely will be fixed to the combat outfit, and they could be placed at any position such as the waist, arm, shoulder or helmet, depending on the specific application.

Once the scientists had created what they needed and obtained the software that allowed them to run their simulations, they performed laboratory-based measurements with simulations of antennas placed on bodies and the communications between those antennas. The researchers built a mockup of the Middle Eastern compound used in the counterinsurgency sweep operation in the scenario. Through the animation software they employed, the researchers moved the troops around and performed simulations to explore how the signal would propagate from soldier to soldier. Cotton shares that the work gave him and his colleagues a good representation of how the system actually would perform.

In the project, researchers proved that short-range soldier-to-soldier communication at 60 GHz is feasible either through direct paths (soldier A to soldier D) or through ad hoc routing (soldier A to soldier D via soldiers B and C), but they have not created the physical antenna array yet. “This would be the subject of follow-on funding,” Cotton explains. He and his organization are working now to expand upon the completed work through cooperation with another research institution. Cotton says he cannot divulge details, but that the partner organization could perform physical measurements that are the key next step for the research.

A benefit of the ad hoc routing demonstrated in the simulation is the ability to maintain network communications over a short distance even if certain links were broken. The soldiers act as nodes in the network, enabling communication between two troops even when they cannot directly access one another. Another benefit is troop and information security.

The communications enhance covert operations through the use of the narrow antenna beamwidth at 60 GHz. Detecting the signal is more difficult than at other frequencies in part because the signal does not travel as far, limiting the chance for interception. Project personnel hope the antenna array eventually would achieve network coverage in excess of a few hundred meters for teams of at least four networked troops.

This image depicts soldiers using the millimeter-wave form to create a mobile ad hoc network as they prepare to enter an enemy command center. The colored rays show simulated millimeter-wave signal propagation between Soldier A and Soldier B.

Cotton explains that exact numbers are difficult to calculate because direct transmission range depends on factors such as transmit power, smart antenna or array gain, system gain and bandwidth. Given the right conditions, researchers believe the antennas could achieve that few hundred meters of network coverage for teams of four or more. For particularly difficult terrains, transmission distances could be sustained by trading any of the transmission-range factors or through the use of disposable repeaters distributed as the team progresses through the theater of operations.

The antenna technology used in this application also aims at overcoming unfavorable propagation characteristics and at aiding covert communications by focusing signal transmissions in carefully chosen directions based on previous message exchanges. It is anticipated that the “direction finding” capabilities made possible by using antenna arrays could be extended to include positioning information from navigational aids such as Global Positioning System readouts depending on the usage scenario. Though Cotton acknowledges no solution is perfect, this antenna array and communication system requires enemies to be in the line of sight or at specific angles to eavesdrop or interfere with the soldier-to-soldier communications.

Cotton shares that millimeter-wave communications can provide a number of benefits for troops, including extremely high data rate communications in excess of 2 gigabytes per second; multichannel streaming of data (for example, real-time video, voice, text); high signal attenuation that prevents signals from traveling far, which offers more secure communications; and high spectral efficiency so channels can be reused over relatively small areas. “The high data bandwidths available at 60 GHz will mean that future systems have the ability of exchanging much more information between troops,” Cotton says.

He adds that military use of the technology will happen sometime in the future, perhaps within the next decade or so as the technologies necessary for the network develop through commercial needs. The doctor believes the use of 60-GHz communications for mobile ad hoc networks between soldiers most likely will be driven by commercial developments linked to streaming high-definition video and personal area networking, as well as future data rate services and the hardware developed to support the standards. He expects that this private-sector demand and development will move the technology forward more so than military applications. When the civilian sector applications reach a certain level of maturity, then the military would adopt them.

Potential private-sector applications for the research include high-bandwidth picocellular communications such as multiple tablet personal computers operating in small areas, high data rate interpersonal, or body-to-body, communications and the exchange of high-definition personal media, such as those from future variants of the iPhone through which people rapidly stream information to one another. Using the 60-GHz band, users could point their smartphones at one another and share high-definition video. The technology also could be used for high data rate services for broadband communications.

According to Cotton, several aspects of the project differentiate it from other antennas and communications systems research. This recent work specifically investigated 60-GHz communications for use by dismounted soldiers. It also exploits signal propagation characteristics at extremely high frequencies to provide desirable attributes for short-range military communications. Cotton says that as far as he and his colleagues know, no one else in the public sector is experimenting with a similar technology. Now that his research is complete, Cotton hopes the work will inspire others to carry on some of the effort and develop some of the necessary technologies. “There’s potential here to take this forward,” he states. “The operating systems at these frequencies are just mind blowing.” In addition to the possible collaboration between Cotton’s organization and the other research institution, he hopes that commercial manufacturers may take it upon themselves to develop necessary technologies to make the simulated study a physical reality.

The future uses and further research opportunities are the key takeaways from the project, the doctor explains. Cotton says that studying communications in the 60-GHz frequency is a whole new area of research. The applicability to military operations, especially covert operations, was shown during the project’s life cycle, and Cotton believes that development efforts will follow.

He also shares that using these frequencies between soldiers enables the real-time video transmission, voice-to-voice and multistreaming capabilities desired by today’s military. The U.S. Army’s Future Force Warrior effort, for example, could achieve some of its goals through the application of this research if the antennas are developed for squad soldiers. The experiment showed the potential for providing dismounted combat soldiers with capabilities beyond those available on the battlefield today in terms of exchanging various forms of information. Cotton says the research will help improve situational awareness, and use of the millimeter-wave form would provide a tactical edge in combat.

WEB RESOURCES
Centre for Secure Information Technologies: www.csit.qub.ac.uk
Defence Science and Technology Laboratory: www.dstl.gov.uk
Centre for Defence Enterprise: www.science.mod.uk/engagement/enterprise.aspx