RF self-interference canceller prototype for 100-W full-duplex operation at 225-400 MHz

Military applications require more and different characteristics from in-band full-duplex radio technology than what the research prototypes developed for civil/commercial applications can offer. While the challenge of cancelling the strong transmit-receive coupling, i.e., self-interference (SI), in a full-duplex radio has been largely resolved at higher ultra high frequency (UHF) bands for low-power transmission, tactical communication and electronic warfare applications require major research efforts toward supporting lower military-relevant frequencies and significantly higher transmission power levels. In this paper, we present a prototype of a radio-frequency SI cancellation circuit for the lower UHF band at 225-400 MHz and transmit power of up to 100-200 W. The experimental results demonstrate that the canceller can suppress SI by 40-50 dB depending on the operation frequency within the band. It is targeted for the military application of simultaneous full-duplex jamming and interception of communications, where we can estimate that a 5-W signal-of-interest could be intercepted from 10 km away when simultaneously jamming with 100 W power.publishedVersionPeer reviewe

Tactical Military Communication Networks of the Future .

Military communication has the added dimension of mobility and bandwidth conservation. The paper deals with the necessity of advanced concepts of communicating images. data and fax in addition to voice as dictated by the command and control requirements. The Integrated services digital network as applied to tactical network of the future is presented. The topics of routing, encryption, mobile access, digital links are briefly covered. The importance of standards of CCITT and contemporary techniques like B-ISDN, cellular radios are discussed. The relevance of network management and its main features are brought out

Design of RF Self-interference Cancellation Circuit for 100-W Full-Duplex Radio at 225-400 MHz

The full-duplex (FD) technology enables future military radios to simultaneously transmit and receive (STAR) on the same and adjacent frequencies. This enhances spectral efficiency and makes simultaneous integrated tactical communications and electronic warfare operations possible as opposed to the current time- or frequency-division radios used in military applications. The main challenge in implementing full-duplex radios is the strong self-interference (SI) between the transmitter and the receiver requiring solutions how to cancel the coupling, which has been largely resolved at higher ultra high frequency (UHF) bands for low power transmission. This paper presents a radio-frequency SI cancellation circuit suitable especially for very high-power military applications at military-relevant lower UHF band (225-400 MHz). The circuit couples power from the transmitter and tunes the phase and amplitude of the signal to destructively combine with the received SI, and thus isolates the receiver and transmitter. The paper introduces a concept consisting of a 90° vector modulator and switchable delay lines for a low-loss and high-power-handling cancellation circuit that enables operation with very-high transmit powers of even up to 1 kW.acceptedVersionPeer reviewe

Multifunction Radios and Interference Suppression for Enhanced Reliability and Security of Wireless Systems

Wireless connectivity, with its relative ease of over-the-air information sharing, is a key technological enabler that facilitates many of the essential applications, such as satellite navigation, cellular communication, and media broadcasting, that are nowadays taken for granted. However, that relative ease of over-the-air communications has significant drawbacks too. On one hand, the broadcast nature of wireless communications means that one receiver can receive the superposition of multiple transmitted signals. But on the other hand, it means that multiple receivers can receive the same transmitted signal. The former leads to congestion and concerns about reliability because of the limited nature of the electromagnetic spectrum and the vulnerability to interference. The latter means that wirelessly transmitted information is inherently insecure. This thesis aims to provide insights and means for improving physical layer reliability and security of wireless communications by, in a sense, combining the two aspects above through simultaneous and same frequency transmit and receive operation. This is so as to ultimately increase the safety of environments where wireless devices function or where malicious wirelessly operated devices (e.g., remote-controlled drones) potentially raise safety concerns. Specifically, two closely related research directions are pursued. Firstly, taking advantage of in-band full-duplex (IBFD) radio technology to benefit the reliability and security of wireless communications in the form of multifunction IBFD radios. Secondly, extending the self-interference cancellation (SIC) capabilities of IBFD radios to multiradio platforms to take advantage of these same concepts on a wider scale. Within the first research direction, a theoretical analysis framework is developed and then used to comprehensively study the benefits and drawbacks of simultaneously combining signals detection and jamming on the same frequency within a single platform. Also, a practical prototype capable of such operation is implemented and its performance analyzed based on actual measurements. The theoretical and experimental analysis altogether give a concrete understanding of the quantitative benefits of simultaneous same-frequency operations over carrying out the operations in an alternating manner. Simultaneously detecting and jamming signals specifically is shown to somewhat increase the effective range of a smart jammer compared to intermittent detection and jamming, increasing its reliability. Within the second research direction, two interference mitigation methods are proposed that extend the SIC capabilities from single platform IBFD radios to those not physically connected. Such separation brings additional challenges in modeling the interference compared to the SIC problem, which the proposed methods address. These methods then allow multiple radios to intentionally generate and use interference for controlling access to the electromagnetic spectrum. Practical measurement results demonstrate that this effectively allows the use of cooperative jamming to prevent unauthorized nodes from processing any signals of interest, while authorized nodes can use interference mitigation to still access the same signals. This in turn provides security at the physical layer of wireless communications

New challenges in wireless and free space optical communications

AbstractThis manuscript presents a survey on new challenges in wireless communication systems and discusses recent approaches to address some recently raised problems by the wireless community. At first a historical background is briefly introduced. Challenges based on modern and real life applications are then described. Up to date research fields to solve limitations of existing systems and emerging new technologies are discussed. Theoretical and experimental results based on several research projects or studies are briefly provided. Essential, basic and many self references are cited. Future researcher axes are briefly introduced

Post-Westgate SWAT : C4ISTAR Architectural Framework for Autonomous Network Integrated Multifaceted Warfighting Solutions Version 1.0 : A Peer-Reviewed Monograph

Police SWAT teams and Military Special Forces face mounting pressure and challenges from adversaries that can only be resolved by way of ever more sophisticated inputs into tactical operations. Lethal Autonomy provides constrained military/security forces with a viable option, but only if implementation has got proper empirically supported foundations. Autonomous weapon systems can be designed and developed to conduct ground, air and naval operations. This monograph offers some insights into the challenges of developing legal, reliable and ethical forms of autonomous weapons, that address the gap between Police or Law Enforcement and Military operations that is growing exponentially small. National adversaries are today in many instances hybrid threats, that manifest criminal and military traits, these often require deployment of hybrid-capability autonomous weapons imbued with the capability to taken on both Military and/or Security objectives. The Westgate Terrorist Attack of 21st September 2013 in the Westlands suburb of Nairobi, Kenya is a very clear manifestation of the hybrid combat scenario that required military response and police investigations against a fighting cell of the Somalia based globally networked Al Shabaab terrorist group.Comment: 52 pages, 6 Figures, over 40 references, reviewed by a reade

EMERGENT BEHAVIOR ANALYSIS OF MARITIME OVER-THE-HORIZON COMMUNICATION USING LASERS AND SPACE PLATFORM RELAYS

This thesis studied an over-the-horizon (OTH) maritime laser communication concept using free-space optics (FSO) and space-based relays. This thesis applied a systems engineering analysis approach to study stakeholder needs, identify requirements, and develop a conceptual design of the FSO concept. Three concept of operations scenarios were developed to illustrate (1) land-to-maritime, (2) maritime-to-land, and (3) maritime-to-maritime communication transmission. The three conceptual FSO communication capability scenarios were modeled using the behavioral modeling tool, Monterey Phoenix (MP). The MP models could be varied to represent nominal, or clear atmospheric conditions, and off-nominal, or poor atmospheric conditions (e.g., precipitation, thermal turbulence, absorption, and scattering). The thesis analyzed expected, unexpected, and emergent behavior using the MP model. The results yielded event traces characterized by transmission time, success data, and behavior expectation data. The MP model analysis produced a pattern of unexpected or emergent behavior that would interfere with successful communication transmission. Laser system failures, ship movement, or operator issues are possible emergent behavior factors. The study results indicated that the FSO OTH communication system could transmit communication quickly and with high data rates, but only during nominal or fair atmospheric conditions.ONR, Arlington, VA 22217Lieutenant, United States NavyApproved for public release. Distribution is unlimited

Internet Protocol (IP) Over Link-16

The purpose of Link- 16 is to exchange real-time tactical data among units of the United States and allied forces. Primary Link- 16 functions include exchange of friendly unit position and status data, fl%the dissemination of tactical surveillance track data, and the control/management of air, surface, and subsurface engagements. Because Link- 16 will play an integral role in fl% network-centric Joint Battlespace Infosphere (JBI), the performance of Internet Protocol version six (IPv6) and IP Security (IPSec) over Link-16 needs to be determined. Using OPNET modeling software to simulate a Link- 16 network, the investigation of this research revealed that the overhead from IPv6 and IPSec does not significantly affect end-to-end delay and effective throughput of the Link- 16 network. As long as the encryption and authentication protocols are preprocessed, these protocols add minimal amounts of latency overhead to the Link- 16 network. However, as the offered load is extended beyond the 90% level, the overhead from the IPSec extensions begins to have more of a negative effect on the End-to-End delay and throughput. Therefore, as the offered load increases beyond the 90% level, it begins to have a significant impact act on the performance of the Link- 16 network

Rapid Response Command and Control (R2C2): a systems engineering analysis of scaleable communications for Regional Combatant Commanders

Includes supplementary materialDisaster relief operations, such as the 2005 Tsunami and Hurricane Katrina, and wartime operations, such as Operation Enduring Freedom and Operation Iraqi Freedom, have identified the need for a standardized command and control system interoperable among Joint, Coalition, and Interagency entities. The Systems Engineering Analysis Cohort 9 (SEA-9) Rapid Response Command and Control (R2C2) integrated project team completed a systems engineering (SE) process to address the military’s command and control capability gap. During the process, the R2C2 team conducted mission analysis, generated requirements, developed and modeled architectures, and analyzed and compared current operational systems versus the team’s R2C2 system. The R2C2 system provided a reachback capability to the Regional Combatant Commander’s (RCC) headquarters, a local communications network for situational assessments, and Internet access for civilian counterparts participating in Humanitarian Assistance/Disaster Relief operations. Because the team designed the R2C2 system to be modular, analysis concluded that the R2C2 system was the preferred method to provide the RCC with the required flexibility and scalability to deliver a rapidly deployable command and control capability to perform the range of military operations