Download or read book Frequency Hopped M arcy Frequency Shift Keyed Communications Using List Metric Decoding Over Jamming and Multiple Access Channels written by Mark A. Creighton and published by . This book was released on 1986 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: List metric decoding is applied to anti-jam and multiple access communication systems that employ frequency-hopped, M-ary Frequency Shift Keyed (MFSK) modulation. The performance of these systems over Guassian noise and Rayleigh fading channels is analyzed by deriving expressions for the cutoff rate parameter RO, and evaluating numerical examples. RO represents the largest reliable data rate per coded symbol that could be achieved, with a particular system and channel, by using practical coding methods. Because it is code-independent, RO is used as the basis for comparing list decoding against hard and soft decisions, without the encumbrance of analyzing specific error correcting codes. RO is then used later, along with a code-dependent function, to upper bound the bit error probability provided by a particular code. In a list decoding receiver, decisions are based on the relative magnitudes of the demodulator's energy detector outputs.
Download or read book Frequency Hopped M ary Frequency Shift Keyed Communications Using List Metric Decoding Over Jamming and Multiple Access Channels written by Mark Alan Creighton and published by . This book was released on 1986 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1987-05 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1987 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Digital Communications with Chaos written by Wai M Tam and published by Elsevier. This book was released on 2010-07-07 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1970's, there has been a great deal of research effort spent on studying chaotic systems and the properties of the chaotic signals generated. Characterized by their wideband, impulse-like autocorrelation and low cross-correlation properties, chaotic signals are useful spread-spectrum signals for carrying digital information. Spectrum spreading has become one of the most popular modulation techniques for high-speed wireless communications. It makes use of signals of very wide bandwidth to carry information at relatively low data rates, and possesses advantages such as low probability of interception, resistance to jamming, multiple-access capability and mitigation to multipath effect, which are particularly important in a wireless scenario. In addition to enjoying the aforementioned benefits, chaotic signals can be generated using simple circuitries, thus lowering the cost of transceivers. Early study of chaos-based communication systems was focused on a single-user case. In the past few years, more effort has been put on investigating systems with multiple-access capability, which is a key feature of spread-spectrum communication systems. Digital Communications with Chaos presents a detailed study of some multiple-access schemes used for chaos-based communications, and evaluates their performance. In addition, the effectiveness of the multiuser detection techniques, whose primary objective is to reduce interference between users and hence improve performance, is evaluated in the context of multiple-access digital communication systems. Hot research topic Describes communication technologies for the future Authors among the pioneers researching in chaos-based communications
Download or read book Government Reports Annual Index written by and published by . This book was released on 1987 with total page 1256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Download or read book Multiple Access Performance of Frequency hopped MFSK with List Metric Detection Over Additive Power Channels written by Mark Alan Creighton and published by . This book was released on 1984 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1987 with total page 1260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Robust Frequency Hopping System for Channels with Interference and Frequency Selective Fading written by and published by . This book was released on 2007 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A robust frequency-hopping system with noncoherent detection, iterative turbo decoding and demodulation, and channel estimation is presented. The data modulation is the spectrally compact nonorthogonal continuous-phase frequency-shift keying, which strengthens the frequency-hopping system against multiple-access interference and multitone jamming. An analysis based on information theory provides the optimal values of the modulation index when there is a bandwidth constraint. The channel estimator, which is derived by applying the expectation-maximization algorithm, accommodates both frequency-selective fading and interference. Simulation experiments demonstrate the excellent system performance against partial-band interference.
Download or read book Performance Analysis of Frequency Hopping MFSK M ary Frequency Shift Keying Systems Employing Forward Error Control Coding in the Presence of Hostile Interference written by Jhong S. Lee and published by . This book was released on 1987 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Error probability analyses are performed for a coded M-ary frequency-shift-keying (MFSK) system employing L hops per M-ary word frequency-hopping (FH) spread spectrum waveforms transmitted over a partial-band Gaussian noise jamming channel. The information bit error probabilities are obtained for a square-law linear combining demodulator and for a square-law adaptive gain control (AGC) demodulator, both with forward error control (FEC) coding under conditions of worst-case partial-band noise jamming, using exact analyses of the demodulator performance which include both thermal noise and jamming noise. Parametric performance curves are obtained for both block codes and convolutional codes with both binary and M-ary channel modulations. The results show that thermal noise can not be neglected in the analyses if correct determinations of the optimum order of diversity and the worst-case jamming fraction are to be obtained over the whole range of signal-to-thermal noise and signal-to-jamming ratios. It is shown that the combination of non-linear combining, M-ary modulation, and forward error control coding is an effective strategy against worst-case partial-band noise jamming. However, just as was found to be the case for uncoded systems, the linear combiner is ineffective in worst-case partial-band noise jamming. (Author).
Download or read book Performance of Coded FH MFSK in a Worst Case Tone Jamming Channel written by P. J. Crepeau and published by . This book was released on 1984 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several block and convolutional coding options are considered which are applicable to the noncoherent detection of FH/MFSK (Frequency Hopped/Multiple Frequency Shift Keying) signals in the presence of tone jamming. The tone jamming model used in this report is the worst-case tone jamming for an uncoded system. Using decoded probability of bit error as a performance criterion, we show that large signaling alphabets yield poor performance in a tone jamming environment. Furthermore, when hard-decision quantization is used, the degradation of a coded system in tone jamming over worst-case partial band noise jamming is the same as the corresponding degradation for the uncoded system: 4.3 dB for M=2, 6.3 dB for M=4, 8.3 dB for M=8, and increasing thereafter without bound as M approaches infinity. The poor performance of coded systems with hard-decisions in tone jamming can be improved by about 10 dB by using soft-decision quantization assisted by perfect jammer state side-information. For the binary case the results obtained by using soft-decision quantization are about 1 dB better than those obtained for the partial band noise channel, showing that the worst-case channel for the uncoded system is not necessarily the worst-case channel for a coded system when side-information is available. The use of small alphabets and soft-decision quantization is recommended for coded FH/MFSK systems in a tone jamming environment. A major issue to be addressed in future studies concerns the type of soft-decision decoding to be used. An approach is needed that is realizable and will give performance close to that of pure soft-decisions with side-information while being free of the problems associated with obtaining perfect side information.
Download or read book The Effectiveness of Random MFSK Multiple Frequency Shift Keying Frequency Hopping ECCM Radios Against Worst Case Partial Band Noise Jamming written by L. E. Miller and published by . This book was released on 1986 with total page 525 pages. Available in PDF, EPUB and Kindle. Book excerpt: The system analyzed for bit error rate (BER) performance is frequency-hopped (FH) multiple frequency-shift-keying (MFSK) wherein the M symbol frequency assignments are independently and randomly chosen on each hop, and the information transmission is repeated L times (L-hop diversity) for a soft symbol decision. This FH/RMFSK system is intended to counter systematic follow-on jamming. The reported analysis is of the system's BER in worst-case partial-band noise jamming (WCPBNJ). To be effective, the receiver must employ nonlinear combining of the L hops; several hop weighting schemes are evaluated with different assumptions about available real-time information on relative powers of signal, noise, and jamming. These include adaptive gain control, clipping, hard-decision, and self-normalizing (nonparametric) schemes. It is shown that a simple, self-normalizing receiver, using no jamming state information or measurements, can perform nearly as well as one using a priori values of received noise-plus-jamming powers for adaptive gain control. It is also demonstrated that a hard-decision receiver (majority logic decoding of the L repetitions) achieves an ECCM effect and is viable if the SNR is high. Although the BER varies with jammer power in much the same way as for conventional FH/MFSK (given the parameters M, L, and the unjammed SNR), including a diversity gain for high SNR, FH/RMFSK in general is more vulnerable to WCPBNJ for M greater than 2. Therefore, it is concluded that implementation of effective diversity schemes is feasible, and that for a binary system the additional complexity of random hopping can be assessed to the additional protection gained against follow-on jamming.
Download or read book Coding for Frequency hopped Spread spectrum Channels with Partial band Interference written by Wayne Eric Stark and published by . This book was released on 1982 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of codes on frequency-hopped spread-spectrum channels with partial-band interference is investigated. The asymptotic performance of codes is measured by the channel capacity and the random coding exponent. The performance of specific codes is measured by the bit error probability. The channel models we consider are quite general and include channels with unknown parameters, channels which change with time, and channels with memory. These models are applicable to frequency-hopped spread-spectrum communication systems as well as to several other communication systems. We formulate the problem of communicating over channels with unknown transition probabilities (i.e. communicating over channels with jamming) as a game theory problem with payoff function being the mutual information between the channel input and the channel output. Under certain restrictions it is shown that memoryless coding and jamming strategies are simultaneously optimal strategies. Next we develop simple, yet accurate, models for many channels with memory that arise in practice. The channel statistics are constant for blocks of symbols of fixed length. The receiver is said to have side information if it can determine the channel statistics for each block of symbols transmitted.
Download or read book Frequency Hopping Multiple Frequency Shift Keying Coding and Optimal Partial Band Jamming written by Don J. Torrieri and published by . This book was released on 1982 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of frequency-hopping systems with multiple frequency-shift keying is determined for operation against optimal partial-band jamming. The effects of Reed-Solomon, binary block, convolutional, and concatenated codes are analyzed. Continuous-phase frequency-shift keying with limiter-discriminato demodulation is shown to offer potentially improved performance in frequency-hopping systems. (Author).
Download or read book Capacity of Frequency Hop Spread Spectrum Multiple Access Communication Systems written by M. V. Hegde and published by . This book was released on 1988 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: The information theoretic capacity of frequency-hop spread-spectrum multiple-access communication is considered. In order to account for independent encoding and decoding and private (to the sender and receiver) hopping patterns an interference channel model is adopted with K sender-receiver pairs with the i-th receiver only interested in the message transmitted by the i-th sender. Both synchronous and asynchronous hopping patterns are investigated. Although the channel exhibits memory in the case, we are able to compute the capacity region. The asymptotic normalized sum capacity is also computed. (RH).
Download or read book Interference Suppression in Multiple Access Communications Using M Ary Phase Shift Keying Generated Via Spectral Encoding written by Abel S. Nunez and published by . This book was released on 2004-03-01 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: A conceptual transform domain communication system (TDCS) is shown capable of operating successfully using M-Ary phase shift keying (MPSK) data modulation in a multiple access environment. Using spectral encoding, the conceptual TDCS provides an effective means for mitigating interference affects while achieving multiple access communications. The use of transform domain processing with MPSK data modulation (TD-MPSK) provides higher spectral efficiency relative to other modulation techniques (antipodal signaling and cyclic shift keying) considered previously for TDCS applications. The proposed TD-MPSK technique uses spectral encoding for both data and multiple access phase modulations. Demodulation of the spectrally encoded TD-MPSK communication symbols is accomplished using conventional, multi-channel time domain correlation techniques. Analytic expressions for TD-MPSK probability of symbol error (PE) and probability of bit error (PB) are derived and validated using simulated results over the range of signal-to-noise ratios typically considered for communications. This validation includes scenarios with: 1) multiple access interference, 2) spectral notching, 3) jamming present and 4) combinations of all three. For a J/S of 3.14 dB and a Eb/N0 of 6 dB, PB dropped by up to a factor of 3 for TD-QPSK in a MA environment for the case when spectral notching was present versus the case when spectral notching wasn't present. The cross- correlation between communication symbols of different synchronous users can be made identically zero through proper selection of multiple access phase codes (orthogonal signaling). For a synchronous network containing orthogonal users, PE and PB are unaffected as the number of orthogonal network users increases. For a J/S of 3.14 dB and a Eb/N0 of 6 dB, PB dropped by a factor of 12 for TD- QPSK in a MA environment for the case when spectral notching was present versus the case when spectral notching wasn't present.
Download or read book Frequency Hopping Codes for Multiple Access Channels written by Dušan B. Jevtić and published by . This book was released on 1987 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
