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We develop accurate and robust one-dimensional EXIT chart methods to design raptor codes with binary and higher-order modulations on AWGN channels over any desired range of SNRs. We formulate the check-node degree distribution optimization as a linear program that optimizes a suitable objective function of the desired operating points. The throughput curves predicted by the analysis are easily compared...
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...
In this paper, we investigate a phase randomization technique in order to modify the coherence structure of a chaotically modulated signal. Phase randomization is shown to reduce the detectability of cyclostationary features, introduced by the constant chip rate of the chaotically modulated signal. The chaotic modulation scheme is based on the symbolic dynamics of a modified Bernoulli shift map and...
Unequal error protection (UEP) and rateless coding are both methods used to combat channel uncertainty. With a rateless code, the code rate automatically adapts to the channel quality through the use of incremental redundancy. However, a rateless code lacks the ability to differentiate priorities and all bits suffer the same long delay in poor channel conditions. In contrast, UEP ensures reliable...
The techniques of Terminal transmit adaptation are critical for achieving maximal channel throughput when the link loss exhibits large variation. In this paper, some technical issues regarding transmit power control and mode adaptation in satellite communication (SATCOM) systems are addressed. The transmit adaptation is explored in terms of optimizing the link availability. The analysis extends the...
Efficient use of spectrum requires an accurate determination of interference effects. In this paper, we introduce a radio to radio (R2R) factor that quantifies the interference effects of one radio waveform on another based on multiple waveform properties instead of solely on intermediate frequency (IF) signal power. The R2R factor is formulated as a dimensionless correction term in the victims communication...
This paper investigates the energy-bandwidth trade-off of various relaying strategies over the AWGN channel. The total energy consumption per information bit includes the receiver circuit processing energy at the relay and destination as well as the transmitted energy. With the cooperation of the source and relay, the end-to-end bandwidth efficiency can be improved at the cost of receiver processing...
In this paper we study the problem of active eavesdropping in fast fading channels. The active eavesdropper is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping the transmission between the legitimate parties (Ex mode), and jamming it (Jx mode) - the active eavesdropper cannot function in full duplex mode. In this paper we only consider...
Multiple antenna systems have been shown to provide significant performance improvements for network nodes; however, the vast majority of nodes in military networks will be limited to single channel devices due to mobility (size and power) and ease of use considerations. In this paper we apply a new joint synchronization-pilot sequence (JSPS) optimization design technique to multiple transmitter OFDM...
In this paper, we consider techniques for communicating in the presence of interference. In particular, we consider the simple scenario of a BPSK communication system in the presence of a constant modulus (CM) interferer. Using computer simulations and analytical approximations, we compare the performances of four detectors for recovering the communications signal in an additive white Gaussian noise...
A framework for multiple access protocols supporting the admission and sustenance of concurrent transmissions in Gaussian interference channels (G-IC) encountered in opportunistic unstructured networks or unused spectral bands under quasi-static fading is proposed. Each node is assumed to be equipped with successive decoding capabilities and seeks admission to the network by requesting a minimum rate,...
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