In modern electronic warfare, physical-layer security threats have evolved from traditional jammers to smart jammers. Smart jammers, due to their stealthy nature, make wireless communication systems vulnerable. They can easily deceive a detection system. In this paper, a physical-layer intrusion detection system (PLIDS) for direct-sequence spread-spectrum systems is developed against smart jammers, which is efficient due to its high detection rates, usability, and accuracy. Smart jamming noise is modeled as wide-sense stationary, additive, and colored. This random process is decomposed into a series expansion of independent and uncorrelated random variables. The decomposition helps in designing a signal processing algorithm for PLIDS. The algorithm is easily implemented via correlators. PLIDS is evaluated using a simulated electronic warfare environment, and its performance is measured in terms of detection capability, precision, and accuracy. It performs error-free detection by adjusting its tuning parameter. Moreover, different performance tradeoffs are observed for different values of the tuning parameter. Finally, comparisons of PLIDS are done with competitive intrusion detection systems.

SUMMARY In this paper, anti‐jamming capabilities are proposed for a generic OFDM‐based wireless communication system. The performance of a wireless system may severely degrade in presence of jamming or intentional interferences. A malicious entity can send strong interference or noisy signals in the same transmit frequency band thus preventing the intended receiver to correctly decode the transmitted data. As a countermeasure, our work proposes algorithms and techniques to restore the system performance in presence of such malicious entities. Proposed anti‐jamming system consists of an adaptive framework that adapts itself to varying jammer behavior and wireless environment, and then, it chooses an optimal strategy to effectively cancel out the effect of jamming and channel fading. Optimization problem is formulated as a multi‐objective criterion for maximization of system throughput and minimization of energy consumption. Simulation results computed in Rayleigh fading channels with different wideband jamming modes and powers show that the proposed system effectively cancels out the jamming and channel fading effects thus maximizing the system performance and minimizing cost of energy consumption. Copyright © 2013 John Wiley & Sons, Ltd.

This research work introduces some novel techniques for interference-resilient OFDM wireless communication. Firstly, novel schemes for spatial multiplexing and interference cancelation based on signal subspace estimation are proposed. Secondly, the OFDM system is designed such that it meets three main objectives simultaneously, namely, (i) interference-resiliency, (ii) throughput maximization, and (iii) energy consumption minimization. Interference-cancelation techniques in prior art mostly consider maximization of throughput without any focus on energy consumption. On the other hand, the literature in energy minimization is limited to interference-free environments. Most of the previous techniques also have a drawback that they cannot operate in smart or dynamically changing interference environments. The focus here is on interference-resilient communication with equal attention to both throughput and energy-efficiency maximization in dynamic hostile environments. The optimization problem is formulated, and then optimal policies and switching thresholds are found for throughput and energy-efficient interference-resilient communication. Methodologies for estimating the channel and jammer conditions and then adapting the transmission strategies accordingly are proposed. Moreover, to have an effective defense against smart jamming scenario, a constant-payoff scheme is also introduced. Simulation results are compared with previous techniques that demonstrate the efficacy of proposed research.

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