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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...
While SOA promises great benefits in productivity and flexibility, the tools for securing these systems continue to lag behind. The ideal of SOA security is to provide trusted containers and frameworks that enforce policies established during deployment, and remove security logic and policy from application code completely. Standards such as WS-Security address some of the issues, but enterprise systems...
The platforms and gateways that compose the Airborne Network (AN) exhibit a high degree of heterogeneity, with a variety of IP and non-IP data links hosted on various terminals produced by multiple manufacturers. The lack of an accepted, mature network management architecture for the AN contributes to the risk that there will be a proliferation of separate, stovepiped tools deployed to monitor and...
Telecommunication networks spanning large areas are subject to various failures. A survivable network provisioning scheme addressing multiple levels of network failures, especially disaster failures which may take out many network components, is desirable in the future Internet. In this study, we propose and investigate the characteristics of a multistate multipath provisioning scheme for telecom...
Many Programs of Record are using Service Oriented Architecture (SOA) approaches and supporting technologies to realize net-centricity requirements. Furthermore, emerging solutions offer data sharing across adjacent security enclaves for these programs, including Cross Domain Joint Battlespace Infosphere (XJBI) by AFRL, Cross Domain Web Services Gateway by DISA, and the Cross Domain Collaborative...
In this paper, we present three novel priority-based spectrum allocation techniques for enabling dynamic spectrum access (DSA) networking for non-contiguous orthogonal frequency division multiplexing (NC-OFDM) transmission. With each communication link in the network possessing a specified pair of bit error rate (BER) and throughput requirements for supporting a specific application, the proposed...
Tactical air-to-ground channels present a number of challenges for physical (PHY) layer waveform design including: (i) airborne platform dynamics (i.e., Doppler, frequency offset, jerk, etc.), (ii) benign to severe ground-level multipath, and (iii) partial to full blockage of the line-of-sight (LOS) path. Legacy military waveforms are not sufficiently robust to operate effectively in these severe...
This paper proposes a three-dimensional (3-D) model for narrowband multiple-input multiple-output (MIMO) vehicle-to-vehicle (V-to-V) multipath fading channels that accounts for mutual coupling among both, transmit and receive antenna elements. This model is used to evaluate the effect of mutual coupling on the antenna element patterns and capacity of MIMO V-to-V systems in a variety of urban environments.
For ease of implementation, communications systems have been steadily converted to digital implementations. FPGA technologies and high-quality, high-speed DACs have enabled this trend. While this is commonly done for modern high bit-rate communications systems, legacy systems like the MIL-STD-188-165A modem are not often considered. One issue is the need to up-sample these slower standards by factors...
This paper describes the high bandwidth high throughput (HBHT) government reference architecture (GRA) effort and utilization of dependency structure matrix (DSM) tools to validate the architecture. This paper is intended to show how the development of GRA compliant modules advances both new and time-tested technologies through establishing a standard for above 2 GHz SATCOM terminal modules. The paper...
A key challenge of convergence is delivering high bandwidth imagery, video and data products to the dismounted soldier without the benefit of garrison infrastructure. The Global Broadcast Service (GBS) Joint Program Office (JPO) is realizing this vision with the adaptation of their transportable IP networked satellite terminal into a manpackable Receive Suite (RS) permitting single person transport,...
A handheld software defined tactical VHF/UHF radio used for AM/FM/PM line of sight communications is transformed into a single sideband HF band radio for HF 2G and 3G ALE networking. Military radio convergence presents real challenges to aggregation of widely variant narrowband waveforms. This paper discusses the hardware adaptations that allow a handheld VHF/UHF radio to act as the core radio of...
We study the impact of different levels of relay cooperation on the throughput of a two-hop amplify-and-forward relaying network, where n single-antenna source-destination pairs communicate through a set of single-antenna relays. We focus on two levels of cooperation among the relay nodes, where the relays share either channel state information (CSI) or both CSI and received signals. The high level...
A voice conversation quality over IP networks is mainly affected by the end-to-end delay and the packet-loss rate. Various delay channel environment can cause the early/late arrival packet loss without actual packet loss. To overcome time-variant dynamics of transmission channels for IP telephone services, an adaptive playout-buffer scheduling is proposed. Previous playout-buffer schedulers focused...
In this paper, we provide a feasibility analysis of non-contiguous orthogonal frequency division multiplexing (NC-OFDM) transceivers based on different operating configurations. The selection of these configurations conform to the constraints defined by the spectral masks of the Federal Communications Commission's (FCC), such as out-of-band radiation. Actual spectrum measurement data collected from...
Applications operating over airborne networks are known to perform quite sub-optimally. Transmission control protocol (TCP) based applications often experience very low data throughput, while the user datagram protocol (UDP) based applications suffer high packet loss as well as out-of-order delivery. This is due to the high bit error rate (BER) nature of the wireless links and the high mobility of...
We consider multiple-input multiple-output (MIMO) radar systems with widely spaced transmit and receive antennas. We treat the problem of detecting point targets when one or more target parameters of interest are unknown. We provide a composite hypothesis testing framework for jointly estimating such parameters along with detecting the target while only a finite number of signal samples are available...
Statistics that are obtained from the demodulator are used in a direct-sequence spread-spectrum receiver to provide an estimate of the signal-to-noise ratio. We evaluate the applicability to spread-spectrum multiple-access systems of an SNR estimator that was proposed previously for SNR estimation in systems for which the only disturbance is thermal noise. The proposed estimate does not require the...
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...
The performance of a serially concatenated convolutional code (SCCC) for frequency hopped M-ary phase shift keying communication systems over an additive white Gaussian channel noise (AWGN) in the presence of a partial-band noise jammer is discussed in the paper. The scaling of the log-likelihood ratio (LLR) which improves the SNR dynamic range and the jamming strategy are also discussed in the paper...
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