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In this paper, we will propose a framework for computing detection (Pd) and false alarm (Pfa) probabilities for chip-time differential transmitted-reference (Tc-DTR) receivers over frequency-selective multipath fading channels further impaired by narrow-band interference (NBI). We will show that, when compared to similar non-coherent receiver architectures, Tc-DTR offers an intrinsic robustness to...
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...
Communications and processing for Net-Centric Airborne Networks may become more vulnerable as additional nodes and entities are added to the networks. Accordingly, Information Assurance must provide greater protections in the face of these wider vulnerabilities. The capabilities of legacy systems still provide a basis for IA, but new operating modes mean that new capabilities are needed to mitigate...
Determining an optimal position of an antenna on a platform is not always intuitive. This paper examines the implementation of a genetic algorithm (GA) within XFdtd, a finite difference time domain (FDTD) solver, for its effectiveness in determining an optimal antenna position when compared to a brute force method. XFdtd uses the FDTD method to solve general electromagnetic problems. Built into XFdtd...
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...
A typical military airborne networking scenario involves small groups of relatively closely-spaced aircraft which fly as a unit to perform a common mission. These aircraft need to maintain very long data links with other aircraft in the presence of strong interference from hostile jammers. Due to the physical separation of the aircraft, the time difference of arrival can often be greater than the...
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...
In wireless local area networks that use the Distributed Coordinated Function (DCF) of the IEEE 802.11 Medium Access Control (MAC) protocol, a collision may occur when two or more devices transmit simultaneously. When a collision results in failed reception of a packet, the stations involved increase their backoff window, which decreases the probability of transmission and hence that of further potential...
Reliability support in a tactical area network is crucial since critical information is exchanged to achieve military missions. However, it is extremely challenging due to mobility, unstable channel condition, and possible jamming attack from an adversary. To increase reliability, we propose a new software layer, called thin layer, that controls diversity schemes located at various network layers,...
As advanced communications techniques reach capacity, have reduced performance or system availability, or become unusable, the warfighter must have a reliable, high-capacity communications system in place and standing ready to supplant the degrading systems. Events in the recent past have shown satellites vulnerable to a number of ills or potential problems that could be debilitating. This paper addresses...
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...
In this paper, we introduce a new denial-of-service attack on wireless networks: low-power, distributed jamming network (DJN). DJN is composed of large number of low-power jamming devices, which are deployed in proximity to the target devices. DJN can cause significant damage to target network performance with high energy efficiency. In the paper, we provide a characterization of DJN, demonstrate...
The Hybrid Extension Module (HEM) Prototype implements a NATO C3 Agency (NC3A) concept for future Deployable Headquarter communications infrastructure in support of NATO Response Force (NRF) and Expeditionary Operations. It makes use of a hybrid transmission system composed of IP-converged wireless (WiMAX) and wired (fiber optics) solutions. In 2008, NC3A improved many aspects of the HEM Prototype...
The robustness to jamming signal is an important property for military communication systems. Some previous work has shown that the frequency domain code division multiplexing (CDM) efficiently rejects the interference. In general, however, the jamming signal has higher power than ordinary interference which leads to insufficient jamming rejection performance of these schemes. To mitigate this insufficiency,...
Estimating network parameters from noisy data is a hard problem that can be made even more difficult by the presence of a malicious adversary who may corrupt the measurement process by capturing a trusted node or perturbing data externally. The adversary may have complete knowledge of the networking protocols that rely on the parameter estimates and may adjust its effect on the system to push protocols...
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...
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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