Worst-case Partial-band Jamming Research Articles

Anti-jamming Frequency Hopping System Using Multiple Hopping Patterns

This paper deals with the follower jamming (FJ) and partial-band jamming (PBJ) resistance for the frequency hopping (FH) communication system with low hopping rate over AWGN channel. To gain a comprehensive FJ and PBJ rejection capability, we propose a multi-pattern frequency hopping (MPFH) scheme. In MPFH, the data channel and complementary channel are hopped on separate frequency slots determined by their respective frequency patterns, which will lure the follower jammer out of aiming at the complementary channel, thus mitigating the effect of FJ. Besides, narrow-band receiver is employed to ensure its PBJ rejection capability. We further enhance the proposed scheme by employing convolutional coding and maximum-likelihood decoding. Its upper bounds on bit error rate (BER) are derived under FJ and PBJ, respectively. Effects of three FJ parameters (tracking success probability, jamming duration ratio and jamming bandwidth ratio) and one PBJ parameter (jamming bandwidth ratio) on BER performance of MPFH are investigated versus the conventional FH/BFSK and recently developed differential frequency hopping (DFH) system. Numerical and simulation results show that when under the worst-case FJ, the proposed MPFH performs as well as DFH, but outperforms the conventional FH/BFSK by more than 5 dB; on the other hand, when under worst-case PBJ, the MPFH has the similar BER performance as conventional FH/BFSK, but outperforms DFH by more than 5 dB. The proposed MPFH shows superior jamming rejection performance under both PBJ and FJ.

저속 주파수 도약 방식 위성 데이터링크에서 송수신 신호중첩 및 주파수 다이버시티 적용

본 논문에서는 주파수 도약방식에서는 적용이 어려운 송수신 중첩통신 방식을 DSM형 중계기를 사용하는 위성 데이터링크에 적용하고 항재밍 성능 개선을 위해 잔여 주파수 자원을 주파수 다이버시티에 활용하는 방안을 제안 한다. 시뮬레이션을 통해 제안한 방식에 대한 항재밍 성능과 탐지회피 성능을 분석하였다. 항재밍 성능 분석 결과, 주파수 다이버시티 적용으로 데이터 통신시 18.5dB의 처리이득을 얻을 수 있으며, 500MHz 도약 방식에서 통신단말형태의 재머에 대해 4.8Mbps의 데이터 전송이 가능함을 확인하였다. 또한, 주파수 중첩에 의해 주파수 자원을 최대 2배까지 재사용 가능하며, 데이터 속도를 추정 할 수 있는 D&M 검출기를 대상으로 중첩을 하지 않았을 때 보다 2.5dB LPI 성능이 개선됨을 확인하였다. In this paper, we propose a possibility of usage of carrier superpositioning scheme for a specific slow frequency hopping(SFH) transmission method for the satellite data link in which all of hopping carriers have to be synchronized to DSM transponder of our previous work and usage of frequency diversity in the saved frequency to overcome the SFH disadvantage against jammer. We have analyzed anti-jamming performance and LPI performance and confirmed that the proposed scheme can support data service with 18.5dB processing gain against the worst case partial band jamming and give 2.5dB gain in the LPI performance against D&M detector which can estimate the data rate of unknown signals.

Performance analysis of an FFH/BFSK self-normalising receiver under multitone jamming

Analytical expressions for bit-error probability are derived for a fast frequency-hopping binary frequency-shift-keying (FFH/BFSK) spread-spectrum (SS) communication system based on Taylor-series expansion. The FFH system employs a soft-decision self-normalising receiver against the worst-case multitone jamming (MTJ) and additive white Gaussian noise (AWGN). The authors' analysis, validated by the simulation results, shows that the band MTJ is generally more harmful than the corresponding independent MTJ. Unlike the soft-decision linear-combining receiver, the worst-case partial-band jamming (PBJ) causes slightly poorer bit-error-rate (BER) performance than the corresponding worst-case band MTJ for the self-normalising receiver with diversity. The BER performance of the self-normalising receiver is shown to be significantly better than that of the soft-decision linear-combining receiver under the conditions of the worst-case band MTJ and AWGN.

Limiter-differential detection of a frequency-hopped CPFSK diversity system in partial-band jamming

The error probability achieved by a differential detector with a bandpass limiter preceding the receiver is analyzed for a slow-frequency-hopped CPFSK diversity waveform transmitted over a partial-band noise jamming channel, and is compared to the system's performance without the bandpass limiter. The system's thermal noise is not neglected in the analysis. In principle, each bit is repeated on L different hops, and for the FH/CPFSK system analyzed, these repetitions are combined to yield a soft decision. The main result is that a diversity gain for error rate improvement in worst-case partial-band jamming is realized with the detector preceded by a limiter, but not without the limiter. This is shown by considering the error probability for L=2 in comparison with that for L=1.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Asymptotic performance of M-ary orthogonal signals in worst case partial-band interference and Rayleigh fading

It is shown that for worst-case partial-band jamming, the error probability performance (for fixed E/sub b//N/sub I/) becomes worse with increasing M for (M>16). The asymptotic probability-of-error is not zero for any E/sub b//N/sub I/(>ln 2), but decreases inverse linearly with respect to it. In the fading case, the error-probability performance (for fixed E/sub b//N/sub 0/) improves with M for noncoherent detection, but worsens with M for coherent detection. For large E/sub b//N/sub 0/ the performance of the Rayleigh fading channel asymptotically approaches the same limit as the worst case partial-band jammed channel. However, for values of M at least up to 4096, the partial-band jammed channel does better. While it is unlikely that an M-ary orthogonal signal set with M>1024 will be used in a practical situation, these results suggest an important theoretical problem; namely, what signal set achieves reliable communication.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance of a Normalized Energy Metric Without Jammer State Information for an FH/MFSK System in Worst Case Partial Band Jamming

For a frequency-hopped noncoherent MFSK communication system without jammer state information (JSI) in a worst case partial band jamming environment, it is well known that the use of a conventional unquantized metric results in very poor performance. In this paper, a unquantized energy metric is suggested for such a system. It is shown that with this metric, one can save 2-3 dB in required signal energy over the system with hard decision metric without JSI for the same desired performance. When this very robust metric is compared to the conventional unquantized energy metric with JSI, the loss in required signal energy is shown to be small. Thus, the use of this normalized metric provides performance comparable to systems for which JSI is known. Cutoff rate and bit error rate with dual- k coding are used for the performance measures.

Probability of Error Analyses of a BFSK Frequency-Hopping System with Diversity Under Partial-Band Jamming Interference--Part II: Performance of Square-Law Nonlinear Combining Soft Decision Receivers

In this paper, error probability analyses are performed for a binary frequency-shift-keying (BFSK) system employing <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</tex> hop/bit frequency-hopping (FH) spread-spectrum waveforms transmitted over a partial-band Gaussian noise jamming channel. The performance results for two types of square-law nonlinear combining soft decision receivers under worst-case partial-band jamming are presented. The receivers employ, prior to combining, nonlinear weighting strategies of 1) adaptive gain control and 2) soft limiting (clipping) of the detector output of each channel of the dehopped waveform. Both thermal noise and jamming are included in the analyses. It is shown in the paper that a diversity gain for error rate improvement is realizable for nonlinear combining receivers provided that the noncoherent combining loss is less dominant than the jamming power reduction realized by the weighting strategy. Performance comparisons between linear and nonlinear combining receivers are presented.

Probability of Error Analyses of a BFSK Frequency-Hopping System with Diversity Under Partial-Band Jamming Interference--Part I: Performance of Square-Law Linear Combining Soft Decision Receiver

In this paper, error probability analyses are performed for a binary frequency-shift-keying (BFSK) system employing L hop/bit frequency-hopping (FH) spread-spectrum waveforms transmitted over a partial-band Gaussian noise jamming channel. The error probabilities for the L hop/bit BFSK/FH systems are obtained as the performance measure of the square-law linear combining soft decision receiver under the assumption of the worst-case partial-band jamming. The receiver in our analysis assumes no knowledge of jamming state (side information). Both exact and approximate (multiple bound-parameter Chernoff bound) solutions are obtained under two separate assumptions: with and without the system's thermal noise in the analyses. Numerical results of the error rates are graphically displayed as a function of signal-to-jamming power ratio with L and signal-to-noise ratio as parameters. All of our results, exact and approximate, indicated that the higher number of hops per bit produced higher error probabilities as a result of increased combining losses when the square-law linear combining soft decision receiver is employed in demodulating the multihop-per-bit waveform.