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In this paper, we present the design, implementation, and evaluation of a custom-built wideband RF front-end for enabling dynamic spectrum access communications in software-defined radio platforms. The frontend is designed for wireless operation within the 50 MHz - 2.5 GHz frequency range, and is entirely software-controlled by the platform. Evaluation of the proposed design was conducted using the...
Applications such as situational awareness are becoming more prevalent in highly dynamic tactical mesh networks and are placing high demand on existing RF network capacity. These applications require high aggregate data capacity but have some flexibility in packet by packet latency. Combined radio frequency and free space optical communication within a heavily scintillated atmospheric path behaves...
The desirable features of future optical high-capacity networks include higher stability, reconfigurability and security. In order to enable robust and self-managed automated operation, the network itself should be able to monitor the physical state of the network, automatically diagnose and repair the network, dynamically allocate resources, and redirect traffic. Optical performance monitoring can...
Management of the devices in a Wideband SATCOM enterprise Earth terminal facility (ETF) is currently fragmented among multiple systems, and some of these legacy systems provide only limited functionality. This paper describes the architecture of a consolidated system to manage the elements of an ETF. Such a system can offer a number of benefits. First, the ETF management system can provide a consolidated,...
Recent advances in component technology now make it possible to exploit of the ultraviolet (UV) spectrum for short range, medium bandwidth, low probability of intercept (LPI) communications. BAE Systems will report on analysis of hardware and phenomenology for the near term application of solar blind ultraviolet non line-of-sight communications (SB UV NLOS Comm). Communications in the presence of...
This paper considers the case for using a ??digital IF?? (intermediate format) as an alternative to conventional analog IF (intermediate frequency) for distributing satellite uplink and downlink signals within modern high-capacity military satellite communications Earth terminals. ??Digital IF?? is defined as a purely digital format enabled by digital I & Q (in-phase and quadrature) sampling for...
The paper introduces a new concept of groupwise generalized selection combining (GGSC), denoted by GGSC(n, m, L) , in which there are n groups of generalized selection combining GSC(m, L) where the largest m (in SNR) elements are selected from L independent elements. The paper proves that GGSC(n, m, L) has the same diversity order (DO) as that of MRC with nL elements, denoted by MRC(nL) and GSC(nm,...
In this paper, we investigate the packet transmission delay in a time varying satellite uplink. Specifically, we are interested in bounding the packet transmission delay within the terminal router for uplink traffic in a future satellite network. Previous work has provided delay bounds for wireline networks with a fixed transmission rate. However, these bounds do not apply to the time-varying satellite...
In spite of its proven advantage, realization of affordable multi-functional phased-arrays, combining multiple communication apertures, is hindered by size, weight, and power consumption (SWaP) and cost issues. Incremental improvements in both transmit and receive analog RF chains are being pursued. However, it is difficult to expect revolutionary advances in phased array SWaP using architectures...
The emerging technologies of multiple, cooperative unmanned systems have brought in an exciting period of possibilities, possibilities of solving challenging problems in medical, social, engineering, and military communities. The technologies have also introduced a growing number of new challenges such as resource allocation, communication and coordination, establishment of consensus, and control...
One of the fundamental differences between the terrestrial radio frequency (RF) signal and underwater acoustic signal is long propagation delay. This paper is focused on a scheduling scheme for regional data collection in underwater acoustic sensor networks. Long propagation delay of the acoustic signal causes a serious problem for transmission scheduling. In this paper, we propose an efficient transmission...
The FlexNet-Waveform (FN-WF) is a new, highly-configurable MANET waveform for the international ground-based SDR arena, designed for the new FlexNet-One and FlexNet-Four hardware platforms. To ensure maximum compatibility and interoperability, the FN-WF assumes an IP-based platform with standard COTS protocols on the wired, Ethernet connections, while the wireless links utilize the best practices...
This paper discusses the database structure of an RF taxonomy modeling tool being developed on a Missile Defense Agency (MDA), Phase II, Small Business Innovative Research (SBIR) augmentation contract. The tool is called the communications system taxonomy (CommTax) toolkit. The data model underlying the Commtax toolkit will be available to other users as a framework for the transfer of data to other...
Physical layer simulations and analysis techniques were used to develop the error vector magnitude (EVM) metric specifying transmitter signal quality. These tools also proved to be very useful in specifying lower level hardware unit performance and predicting mobile user objective system (MUOS) satellite 8-PSK transmitter performance before the hardware was built. However, the verification of EVM...
Current DoD requirements call for a single enterprise terminal supporting up to 48/96 (threshold/objective) transmit and 56/112 (threshold/objective) receive communications carriers, not considering future expansion. The number of links supported by an enterprise terminal dictates aggregate servicing capacity. A single teleport/standardized tactical entry point (STEP) site can consist of five or more...
Cognitive radio (CR) is a revolutionary wireless mobile communication technology. Smart users can use the CR technology to sense the surrounding environment, search for available spectrum resources and access spectrum dynamically. Differential frequency hopping (DFH) is known as an effective FH technique for increasing data rate of HF communication system. In this study, the cognitive radio technology...
In this paper, an analytical time-domain model is presented to analyze the radio over free space optical (RoFSO) systems under two turbulence channels, the log-normal and the exponential channel. This analytical model uses general cases of a dual-drive Mach-Zehnder modulator (DD-MZM) and photodetector (PD) for typical optical double sideband (ODSB) and single sideband (OSSB) signals under turbulence...
The Hybrid Extension Module (HEM) Prototype implements a NATO C3 Agency (NC3A) concept for future Deployable Headquarter communications infrastructure in support of NATO Response Force (NRF) and Expeditionary Operations. It makes use of a hybrid transmission system composed of IP-converged wireless (WiMAX) and wired (fiber optics) solutions. In 2008, NC3A improved many aspects of the HEM Prototype...
In this paper, we introduce a wireless LAN design framework for optimal placement of access points (APs) based on detailed coverage area and capacity requirements in the operational environment. The framework provides a combination of optimization algorithms that place APs for maximizing coverage and capacity, while minimizing interference and deployment cost. The framework accurately models RF propagation...
Current U.S. military pursuits, such as the Joint Tactical Radio System (JTRS), are based on a software-defined radio (SDR) system. These kinds of systems use the flexibility of software to make old and new radio technology interoperable. Co-existence of different radio technologies has the potential to be a force enabler, but it still falls short, particularly for military operations in which failure...
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