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MILCOM 2000. 21st Century Military Communications Conference Proceedings

Date 22-25 Oct. 2000

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  • MILCOM 2000 - 21st Century Military Communications Conference Proceedings [front matter]

    Page(s): i - xxvii
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    Freely Available from IEEE
  • Internetworking in the MUOS CAI and the advanced narrowband system

    Page(s): 792 - 796
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    Next generation mobile tactical narrowband systems, embodied in the Mobile User Objective System (MUOS), must plan internetworking operations expected to serve 12 years starting in 2007. MUOS may deploy its own satellite Common Air Intetface (CAI) waveform to serve low rate, high mobility handhelds as well as larger terminals with higher capacity than predecessor UFO. The CAI media access control (MAC) is likely to be specialized to handle fading, interference and ef$cient multiple access. Above the MAC, use of commercial off-the-shelf (COTS) standards and "middleware" for network management, connections and transport can mitigate development and O Mco st and risk on one hand, while exploiting protocol and technology innovations on the other to achieve a "sustainable" internetwork strategy. This paper considers three COTS-based internetworking constructs: I ) a transparent, client-server-based "Access Registry," 2) negotiated connections using Mobile IP for network security, and 3) variable Layer 3-to-MAC CAI data modes using IP or ATM cells with a closer look at an ATMMAC. The three constructs are proposed to be widely applicable across varying CAI MAC and multiple access approaches View full abstract»

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  • Author index

    Page(s): 0_1 - 0_5
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    Freely Available from IEEE
  • Differentially coherent code acquisition in wideband jamming

    Page(s): 1129 - 1133 vol.2
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    This paper considers the use of differentially coherent (DC) matched filter (MF) code acquisition in a direct-sequence (DS) spread-spectrum system. Simulation results in wideband jamming are presented. The performance of structure is compared to conventional noncoherent (NC) MF acquisition. The performance measure is the mean acquisition time, TMA. The results indicate that the differentially coherent method is a robust method by allowing also wideband jamming in quite severe Doppler shifts in addition to previously investigated narrowband interference and data modulation conditions View full abstract»

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  • Building a true anomaly detector for intrusion detection

    Page(s): 1171 - 1175 vol.2
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    While many commercial intrusion defection systems (IDS) are deployed, the protection they afford is modest. At the state-of-the-art, IDS produce voluminous alerts, most false alarms, and function mainly by recognizing the signatures of known attacks so that novel attacks slip past them. Attempts have been made to create systems that recognize the signature of “normal”, in the hope that they will then detect attacks, known or novel. These systems are often confounded by the extreme variability of nominal behavior. This paper describes an experiment with an IDS composed of a hierarchy of neural networks (NN) that functions as a true anomaly detector. This result is achieved by monitoring selected areas of network behavior, such as protocols, that are predictable in advance. While this does not cover the entire attack space, a considerable number of attacks are carried out by violating the expectations of the protocol/operating system designer. Within this focus, the NNs are trained using data that spans the entire normal space. These detectors are able to recognize attacks that were not specifically presented during training. We show that using small detectors in a hierarchy gives a better result than a single large detector. Some techniques can be used not only to detect anomalies, but to distinguish among them View full abstract»

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  • Vulnerabilities in the open shortest path first interior gateway protocol

    Page(s): 1224 - 1228 vol.2
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    In order to reduce the number of successful attacks against the US government's computer networks, resources must be invested not only into implementing known fixes and security measures but also into the identification and correction of vulnerabilities before adversaries can exploit them. This thesis identifies one such vulnerability in the open shortest path first (OSPF) interior gateway protocol. This protocol is responsible for deciding which route network traffic will take, assuming multiple routes exist, in an autonomous system. This vulnerability spoofs routers running OSPF into altering the route that certain traffic takes without introducing abnormalities that would alert system administrators. In addition, this mode of deception can be continued indefinitely or reversed without alerting administrators View full abstract»

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  • Blind estimation of frequency offset in OFDM systems using a nonlinear adaptive filter

    Page(s): 917 - 921 vol.2
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    Orthogonal frequency division multiplexing (OFDM) is a possible candidate for high-rate data transmission in wireline and wireless communications. However, OFDM systems are very sensitive to frequency offset due to Doppler shifts and carrier synchronization errors. This sensitivity causes the system performance to degrade drastically. Therefore, in this paper we propose a blind estimation based an a nonlinear Volterra adaptive filter to estimate and compensate the frequency offset. The results show a significant performance improvement when using the scheme presented in this paper View full abstract»

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  • EHF SATCOM on-the-move testbed description

    Page(s): 1235 - 1238 vol.2
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    This paper describes a software testbed for the development and evaluation of error control techniques for an EHF SATCOM on-the-move system. The testbed consists of a small number of end-user computers connected to one another via a channel simulator (i.e., workstation computer). An overview of the software development effort, including the implementation of error control strategies, the channel simulator, and a few select user applications is presented View full abstract»

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  • LinkwayTM for 21st century military communications

    Page(s): 619 - 623 vol.2
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    To achieve information superiority in the 21st century, military communications will increasingly depend on satellite systems. COMSAT Laboratories has developed a broadband VSAT networking product called LINKWAYTM that, today, provides seamless extension of terrestrial networks using industry-standard protocols. This paper describes LINKWAY's unique features, including its hubless architecture; bandwidth on demand; multiprotocol support (enabling easy migration to future applications); support for asymmetric traffic; and support for single-hop, full-mesh, and star topologies on a single platform. LINKWAY is compatible with the new generation of Internet and multimedia services. Its unique, patented, dynamic bandwidth on demand algorithm distributes network bandwidth across many sites effectively and efficiently. LINKWAY offers today the capabilities that a broadband Ka-band system will provide in the future. A series of architectures is presented to show extensions of LINKWAY for military use View full abstract»

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  • Optical burst switching: the next IT revolution worth multiple billions dollars?

    Page(s): 881 - 885 vol.2
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    All-optical Internet may one day come true, due to the explosive bandwidth requirement, and advances of enabling optical communication techniques. And exactly NOW we are at the turning point. We study one possible optical packet switching technique-optical burst switching. We present the overall network protocol, enabling techniques, architectures, switching cores and performance evaluations View full abstract»

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  • Spatial diversity and high data rate waveforms-is it worth doing?

    Page(s): 1144 - 1148 vol.2
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    In the early days of HF communications, CW and FSK waveforms were the prevalent means for data communications. These tone based signaling methods were very susceptible to frequency selective fading caused by multipath. To improve the reliability of these links, spatial diversity was commonly used. As newer, more robust waveforms were developed for HF, it was felt that spatial diversity was no longer needed. This paper investigates the possible performance improvements of using spatial diversity on modern HF waveforms such as the high data rate waveforms defined in US MIL-STD-188-110B. Several different channel conditions are studied to determine if spatial diversity should perhaps be revisited as a way of further improving the reliability of HF links View full abstract»

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  • Convolutionally coded overlapping multicarrier DS/CDMA systems with arbitrary chip waveforms

    Page(s): 922 - 926 vol.2
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    In this paper, we consider convolutionally coded multi-carrier DS/CDMA systems using overlapping subchannels in time-limited and band-limited channels, and analyze their performance when arbitrary chip waveform and random binary signature sequences are used. It is shown that the proposed system, the convolutionally coded overlapping multi-carrier DS/CDMA system with a symbol mapping method utilizing diversity, outperforms the conventional convolutionally coded systems. It is also shown that the proposed system can provide a larger system capacity and more effectively combat the partial band interference (PBI) than the conventional ones View full abstract»

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  • Space-time processing techniques for detection and copy of co-channel signals

    Page(s): 810 - 815 vol.2
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    In this paper we apply jointly optimized space-time processing techniques to detect and copy signals in the presence of co-channel interferers. In particular, we treat the “overloaded” case where the number of interferers equals or exceeds the number of antennas. The detection technique combines beamsteering (spatial) with multirate subband processing (temporal) to construct the power-frequency-angle datagram (PFAgram). The copy technique is based on a jointly optimized MMSE analysis. The results are shown to include the spatial-only and temporal-only solutions as special cases. The jointly optimized approach affords a multiplicative enhancement in performance due to the exploitation of cross terms in the joint covariance matrix. One feature of this approach is that the PFAgram constructed for detection contains the necessary information to calculate the copy solution. Examples are presented that show successful detection and copy under overloaded conditions View full abstract»

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  • On the comparison of optical WDM mesh network protection strategies

    Page(s): 886 - 891 vol.2
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    This paper presents a comprehensive investigation of three optical wavelength-division multiplexed (WDM) mesh network protection approaches, name minimal cost, single link basis and disjoint path approaches. The operation of each approach is described and their performances are extensively evaluated and compared. Key aspects that are taken into the consideration and comparison of the designs include a spare capacity requirement, ease of operation and practical feasibility. A mathematical model based on integer linear programming is introduced to obtain a lower bound on the spare capacity requirement for full protection against all single link failures. Two heuristic algorithms have also been developed to perform wavelength resource under both normal and failure conditions for both systems with and without wavelength conversion capability. It is shown that the minimal cost approach can accomplish the lowest extra cost requirement for protection, but this approach is considered not appropriate for practical applications due to complicated restoration and management. The single link basis scheme is on the other hand more practical and very cost efficient. For the disjoint path technique, the cost for spare capacity is generally slightly greater than that of the single link basis scheme. Its main advantages lie in the simple reconfiguration and inherent protection against node failure for in-transit traffic. Finally, a new framework for obtaining a good spare capacity cost estimate of a mesh restorable network is presented View full abstract»

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  • Recovery of unknown constraint length and generator polynomials for linear convolutional encoders

    Page(s): 947 - 951 vol.2
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    There are cases where the parameters of a forward error correcting encoder, the constraint length K and the generator polynomials, are unknown and must be obtained before the message data can be recovered. An algorithm is presented which, through observation and manipulation of the encoder data, composes a synthetic impulse response and from this sequence performs encoder parameter recovery. With these parameters in hand, selection of a suitable (Viterbi) decoder is straightforward, as is recovery of message data. The class of encoder examined is feedback-free, rate 1/2, linear, convolutional encoders, and for simplicity the algorithm is presented assuming noise-free data. The algorithm is then generalized to accommodate rate m/n codes View full abstract»

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  • Equalization and decoding in SFH spread-spectrum communications

    Page(s): 764 - 768 vol.2
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    There is an increasing need for tactical mobile radio networks that support link data rates of hundreds of kilobits per second to several megabits per second. If a radio network employing slow-frequency-hop (SFH) spread-spectrum modulation operates at these high data rates, however, the channel is likely to exhibit frequency-selective fading within each frequency slot of the SFH system. The frequency selectivity manifests itself as intersymbol interference at the receiver, and adaptive equalization must be employed in the receiver for each dwell interval in order to compensate for the intersymbol interference. We examine the performance of a SFH spread-spectrum system with Reed-Solomon coding in a channel that exhibits frequency-selective fading within each frequency slot. The performance is evaluated for a receiver that employs maximum likelihood sequence estimation in an equalizer that is retrained on a hop-by-hop basis. The use of parity bits for erasure generation is also investigated View full abstract»

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  • DS/SS code acquisition using a locally suboptimum rank detector

    Page(s): 1134 - 1138 vol.2
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    In this paper signed-rank based nonparametric detectors are used for pseudonoise (PN) code acquisition in direct sequence spread spectrum (DS/SS) systems. We first derive the locally optimum rank (LOR) detector and then propose a locally suboptimum rank (LSR) detector and a modified signed-rank (MSR) detector using approximate score functions. We compare the single-dwell scheme without the verification node using the proposed LSR and MSR detectors with that using the conventional squared-sum (SS) and modified sign (MS) detectors. From the simulation results, it is shown that the proposed LSR and MSR detectors perform better than the MS detector by about 2~3 dB and are nearly optimum View full abstract»

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  • Adaptive signaling schemes with imperfect channel-quality estimates in wireless CDMA communications

    Page(s): 851 - 855 vol.2
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    Adaptive signaling techniques can be used to more-efficiently utilize system resources in wireless communication systems. We have previously shown that adaptive signaling with non-uniform M-ary phase-shift-keying can improve the throughput in a CDMA wireless communication system. This additional throughput can be used to include a second multimedia message, called an additional message, along with the standard message that would be transmitted without the use of adaptive signaling. The schemes that we have investigated adapt the spacing of points in the signal constellation and the code rate and signaling rate for the additional message. Techniques that employ only adaptation of the code rates for both messages have also been suggested to achieve this same goal. In this paper we analyze the effects of imperfect channel estimates on the performance of adaptive signaling schemes that use nonuniform signaling and schemes that adapt only the code rate. The results show that, in a variety of situations, the nonuniform signaling schemes provide a higher throughput than the schemes that use uniform constellations. We also analyze the effect of using code-combining automatic repeat request (ARQ) with these adaptive techniques View full abstract»

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  • The ability to provide services in military radio networks: a feasibility study

    Page(s): 1006 - 1010 vol.2
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    A tactical multi-hop ad hoc radio network is assessed in terms of the ability to fulfill different services in different situations. The wireless network we have in mind consists of many units, or radio terminals, and is independent of any fixed communications infrastructure. The particular test case we model and investigate is a radio network for a Swedish mechanized battalion. To model the propagation in terrain we use a multiple edge diffraction model and a digitized terrain model. Each radio terminal consists of adaptive capable wideband radio equipment and uses an omni-directional antenna. The three type of services we consider are: situation awareness data, group calls and data base retrievals. We consider using the 450 MHz or the 2 GHz frequency band. For these frequency bands different terrain and networks are tested. The size of the area that the units are moving in, and how they are spread out in this area is varied View full abstract»

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  • Mission utility evaluation of the AEHF system

    Page(s): 1176 - 1180 vol.2
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    Mission utility analysis has been utilized to provide a systematic link between the performance requirements for a protected satellite communications system and the outcome of a two major theater war military campaign. The results of this analysis are consistent with the findings of the Defense Science Board report on DoD communications. The mission utility analysis links communications message needs to individual military missions. It provides an evaluation of the sensitivity of key threshold to objective requirements to utility. Key performance areas with impacts on mission utility include system capacity and network architecture approaches, such as packet switching. The analysis identifies the impact of increasing demand for time critical messages on mission utility View full abstract»

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  • Design of fiber Bragg gratings using the simulated annealing technique for an ideal WDM filter bank

    Page(s): 892 - 896 vol.2
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    We propose new methodology for designing an ideal bandpass filter as a cascade of two piecewise uniform fiber Bragg gratings (followed by a 100% fiber-optic reflector). With the expense of a more complicated structure, we are able to obtain an almost ideal bandpass filter with a constant group delay. The first piecewise-uniform fiber Bragg gratings are designed to get the desired (i.e., rectangular) bandpass amplitude spectrum. The second piecewise-uniform fiber Bragg gratings (together with the reflector) are designed to flatten the group delay characteristics of the first fiber Bragg gratings. The parameters of fiber Bragg gratings are determined by using the simulated annealing technique followed by the steepest descent algorithm View full abstract»

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  • Analysis of third-generation HF ALE technologies

    Page(s): 1139 - 1143 vol.2
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    Third-generation HF automatic link establishment (ALE) achieves order-of-magnitude improvements over second-generation ALE in linking speed, network size, and traffic capacity. We examine the individual contributions to this performance by several of the techniques standardized in the third generation, including synchronous operation, dwell groups, and separate calling and traffic frequencies View full abstract»

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  • Inserting turbo code technology into the DVB satellite broadcasting system

    Page(s): 650 - 654 vol.2
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    This paper illustrates the potential benefits of inserting turbo code technology into emerging communication satellite systems. This paper considers the application of turbo codes to the digital video broadcasting (DVB) standard, which is based on the concatenation of a Reed-Solomon code and a convolutional code. We show that by simply replacing the convolutional code with a turbo code, a 1 dB improvement in coding gain can be achieved in an AWGN channel. This benefit is obtained with no loss in code rate and only a moderate increase in decoder complexity. Furthermore, since Reed-Solomon coding is used to correct burst errors at the output of the turbo decoder, the problematic “bit error rate floor” experienced by unprotected turbo codes is practically eliminated. We then discuss methods for extending the improvement to 2 dB by using larger frame sizes and more efficient Reed-Solomon codes. We conclude with a survey of other methods that can be used to achieve further performance improvements View full abstract»

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  • A rate adaptive convolutional coding method for multicarrier DS/CDMA systems

    Page(s): 932 - 936 vol.2
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    In this paper, a rate adaptive convolutional coding method for multicarrier direct sequence code division multiple access (DS/CDMA) systems is considered In order to accommodate a number of coding rates easily and make the encoder and decoder structure simple, we use the rate compatible punctured convolutional (RCPC) code. We obtain data throughputs at several coding rates by choosing the coding rate which has the highest data throughput in the SINR sense. To achieve maximum data throughput, a rate adaptive system based on the channel state information (the SINR estimate) is proposed. The SINR estimate is obtained by the soft decision Viterbi decoding metric. We show that the proposed rate adaptive convolutionally coded multicarrier DS/CDMA system can enhance spectral efficiency and provide frequency diversity View full abstract»

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