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This research explores the feasibility of performing passive information capture on voice data in order to analyze and classify the contents of interpersonal communication. The general form of this problem is very difficult as fully automated speech understanding technology does not exist. This is further complicated by battlefield realities including: noise, jargon and unstructured speech. However,...
This paper considers a synchronous DS-CDMA system where channel state information at the base station is acquired via uplink training and channel feedback is used to provide the terminals with the optimal uplink signatures. We examine the tradeoffs involved in the proportioning of a resource block between training, data, and feedback symbols, with linear (matched filter and minimum mean-square error)...
The Crame??r-Rao bound for the joint estimator of carrier frequency offset, carrier phase offset, and symbol timing offset for offset QPSK is derived and used to identify ??good?? training sequences. Conveniently, sequences that repeat a single OQPSK constellation point are found to be the ??best?? for all three estimators when half-sine pulse shaping is used.
The prerequisite of accessing white spectrum is to find and locate it. Our work deals with spectrum detection and recognition under the umbrella of cognitive radio. In the procedure of spectrum recognition, a frequency sweeping device sweeps the wideband spectrum and the samples of the wideband power spectrum density (PSD) are fed into different hidden Markov models (HMMs) sequentially. The core idea...
We introduce complete analytical characterization of the nonlinear interference that results when passing more than one high-order modulation carrier through the same nonlinear transponder HPA. Based on this analysis, a novel Volterra filter is proposed that models nonlinear intersymbol interference (ISI) and adjacent channel interference (ACI). Our focus is on adaptive algorithms so that the solutions...
Integration of Commercial Off The Shelf (COTS) technology into MILSATCOM terminals may offer benefits over custom solutions. These include more affordable network nodes; reduction in development, acquisition, training, and sustainment expenditures; improved terminal interoperability; and, with modular integration, the ability to more easily incorporate future networking technology. This paper discusses...
An organization consists of many resources and entities who want to access those resources. Not all entities are granted full access rights to every resource, so there must be a Trust Management System (TMS) in place to enforce access rights. In this paper, we present a new Hybrid Trust Management System (HTMS) that combines Role Based Trust Management (RBTM) with Reputation Systems (RS). At any point...
With last year's activation of US African Command (AFRICOM), the United States will now address its security concerns for that turbulent continent with operations realigned under one command instead of three. Information operations will necessarily dominate the Department of Defense's activities in Africa - genocide, poverty, famine, epidemic and civil war are rarely if ever amenable to solution by...
In this paper, we investigate the information theoretical performance of a cooperative OFDM (orthogonal frequency division multiplexing) system with imperfect channel estimation. Assuming the deployment of a training-aided channel estimator, we derive a lower bound on the achievable rate for the cooperative OFDM system with amplify-and-forward relaying over frequency-selective Rayleigh fading channels...
Carrier sense multiple access (CSMA) is the conventional medium access method used in wireless ad hoc networks. it can be enhanced as a space-division based CSMA (namely, SD-CSMA) by using multi-antenna techniques, which allows concurrent link communications in the network. In this paper, we present a MAC design that can adaptively switch between CSMA and SD-CSMA in multi-antenna based ad hoc networks...
Polymorphic attacks threaten to make many intrusion detection schemes ineffective. In order to address the threat of advanced attacks, model based techniques are required. In this paper we improve our Grammar Based Modeling techniques to be more resilient to attacks that change in form by using advanced classification techniques. Similarity distances from known models are input as features input to...
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