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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...
A critical aspect of spectrum sensing involves determining the number and type of transmitters in the band of interest. We present a technique that exploits a combination of temporal and frequency-based analysis to enable significantly more accurate frequency offset measurements than would be possible with frequency domain measurements alone, thus enabling improved RF fingerprinting for frequency...
Frequency-hopping (FH) spread-spectrum anti-jam systems are susceptible to degraded performance by follower jammers, which intercept the transmitted signal, attempt to determine in which of a number of bins the hop is located, and then jam in that bin only. Three factors are addressed that provide some protection against follower jammers. One is the differential time delay between the direct intended...
Communication systems must maintain tight timing synchronization between the transmitter and receiver. Systems typically pull-in timing from a large timing offset and then track timing once it has been sufficiently pulled in. When timing errors are large, additional reference symbols are needed to pull-in time. In some frequency hopping systems, the time pull-in step must be repeated for every hop...
Frequency hopping provides some protection against multiple access interference in random-access ad hoc networks. Power control and the use of short routing hops can further reduce interference by promoting spatial reuse. If the network is fully connected, frequency hopping and power control alone may be sufficient to allow good throughput without the use of routing. This approach is particularly...
Cognitive radio (CR) is a revolutionary wireless mobile communication technology. Smart users can use the CR technology to sense the surrounding environment, search for available spectrum resources and access spectrum dynamically. Differential frequency hopping (DFH) is known as an effective FH technique for increasing data rate of HF communication system. In this study, the cognitive radio technology...
This paper presents simulation results which illustrate the performance of a fast frequency hopped - frequency division multiple access (FFH-FDMA) satellite communication system using a partial processing dehop-rehop transponder (DRT) under jamming. In the simulated system, convolutional coded symbols (using rates 1/2 or 1/4) are hopped with time diversity to enhance the anti-jamming (AJ) capacity...
Effective adaptation of error-control coding in a packet radio network requires certain statistics to be developed in the demodulator and decoder of the receiving radio during the reception of each packet. The statistics from one packet are employed to select the code for the next packet. The design and evaluation of cross-layer protocols that use such statistics typically require numerous simulations...
The Link-16 is the tactical data link utilized by the Joint Tactical Information Distribution System (JTIDS). The JTIDS system is important due to its wide use by U.S. armed forces, NATO, and other allied militaries. Link-16 is a hybrid frequency-hopped/direct sequence spread spectrum system that utilizes minimum-shift keying (MSK) to modulate the chips, cyclical code-shift keying (CCSK) to modulate...
Iterative signal processing has gained in popularity over the last decade as a way of reducing the effects of interference in a communication system. In previous work, the expectation maximization (EM) algorithm was used to estimate the parameters and data of colliding transmissions in a slow frequency-hopping spread-spectrum (FHSS) system using binary frequency-shift keying (BFSK). As in many FHSS...
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...
The effects of adaptive-rate transmissions and routing on the total throughput of a slow-frequency-hop packet-radio network are considered. Adaptive rates are achieved through the use of error-control coding with perfect side information. Both fixed-length codes and variable-length codes are considered. Performance results are obtained for direct transmission (i.e., no routing), two-hop limited routing,...
We consider the problem of identifying the insider-based attacks in the form of jammers in a single-hop wireless network, where jammers have the inside knowledge of frequency hopping patterns and any protocols used in the wireless network. We propose a novel technique, called ??alibi??, to identify the insider-based jammers in multi-channel wireless networks. Alibi is a form of defense whereby a defendant...
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