Partial-band Noise Interference Research Articles

Detection and countermeasure of interference in slow FH/MFSK systems over fading channels

In this paper, we present an algorithm to detect unknown interference in slow frequency-hopped M-ary frequency-shift-keying (SFH/MFSK) systems over fading channels. Both partial-band noise interference (PBNI) and multitone interference (MTI) are considered. The proposed algorithm performs the detection process after dehopping by making use of square-law detectors. We first analyze the statistical property of the outputs of the square-law detectors over one hop duration, and an appropriate threshold level is derived for detecting the interference based on a binary hypothesis testing. We also formulate the closed-form expressions for the probabilities of detection of both types of interference experienced in any particular frequency hop. The analytical results are validated by the simulation results and they reveal that the proposed algorithm is able to provide good detection performance for both types of interference and outperforms the conventional ratio–threshold test (RTT) method.

Interference detection in slow frequency‐hopped quadrature phase‐shift‐keying systems over fading channels

In this study, the authors present an algorithm to detect unknown interference in slow frequency-hopped quadrature phase-shift-keying systems. Both partial-band noise interference and multitone interference are considered. The algorithm is developed based on the correlator outputs over one hop. A suitable threshold level is derived for detection. The authors formulate the analytical expressions for probability of detection for both interference models. Numerical results reveal that the proposed algorithm can detect both interference types even at low interference power.

Study of LDPC Coded SFH System with Partial-Band Interference

The application of Low Density Parity Check (LDPC) code in the anti-interference systems has drawn an increasing attention, due to its admiring performance which is very close to the theory limit. This paper focuses on a LDPC encoded slow frequency hopping (SFH) communication system with partial-band interference. Firstly, a modified soft- decision algorithm based on the utilization of interference information is proposed, and its performance is compared with some other soft-decision methods. Secondly, with numerical simulation, the influence of code rate, code length and the number of symbols per hops on the performance of the system with partial band noise interference is illustrated and examined in detail. Considering the great influence of hops per symbol on the performance, interleaver should be used and its influence on the performance is further examined by simulation. Finally, some constructive advises for the design of LDPC coded SFH system are given. Simulation results show that, with a reasonable design, the SFH system with LDPC code could achieve a desirable performance.

A Novel Approach to the Analysis of Diversity Receivers Corrupted by Partial-Band Noise Interference

Bit error rate performance analysis for communications systems with diversity and partial-band interference often yields complicated probability density functions (PDFs) for the decision statistics. The authors calculate these PDFs via a new technique by evaluating the inverse Laplace transform as an integral of a real integrand over a finite range.

Effects of partial-band noise interference on hybrid DS/SFH MSK system in Rayleigh fading channel

The effects of partial-band noise interference on the hybrid DS/SFH MSK system in a Rayleigh fading channel are analysed and discussed. In an AWGN channel, the worst case BER is caused by the partial-band interference for large signal-to-interference ratio (SIR), and full-band interference for small SIR, respectively, independent of signal-to-noise ratio (SNR); whereas, in a Rayleigh fading channel, the full-band interference always results in the worst BER, independent of both SNR and SIR.

Adaptive timing synchronisation scheme for short-range Bluetooth network

An adaptive timing synchronisation scheme for a short-range Bluetooth system in partial-band noise environments is presented. The variance of the partial-band interference is estimated and is used for the trigger threshold value of the inquiry scan and page scan states. Numerical results show the proposed synchronisation algorithm is robust to partial-band noise interference and is of low complexity, which makes it suitable for use in low-cost personal area networks.

Adaptive timing synchronization schemes for a short-ranged Bluetooth system

This paper describes two adaptive timing synchronization schemes for a short-ranged Bluetooth system in the partial-band noise environments. One estimates the variance of the partial-band interference, which is utilized for the trigger threshold value of the inquiry scan and page scan states, while second is designed using the scaled partial correlation value for the connection state. Numerical results show the proposed synchronization algorithms are robust to the partial-band noise interference and of low complexity which is suitable for a low-cost personal area network (PAN).

Performance of a fast frequency-hopped noncoherent MFSK receiver with nonideal adaptive gain control

An error probability analysis is performed for an orthogonal noncoherent M-ary frequency-shift keying (MFSK) communication system employing fast frequency-hopped (FFH) spread spectrum with diversity. The signal is assumed to be transmitted through a frequency-nonselective slowly fading channel with partial-band noise interference. The partial-band interference is modeled as a Gaussian process. Both the information signal and the partial-band noise interference signal are assumed to be affected by channel fading; it is assumed that the two fading processes are independent and that channel fading need not necessarily affect the information signal and the interference signal in the same way. Each diversity reception is assumed to fade independently according to a Rician process. Adaptive gain control is employed to minimize partial-band interference effects, and the effect of inaccurate noise measurement on the ability of the adaptive gain control receiver to reject partial-band interference is examined. The effect of thermal noise is included in the analysis.

Coding for Frequency-Hopped Spread-Spectrum Communication with Partial-Band Interference--Part I: Capacity and Cutoff Rate

The performance of optimal codes on frequency-hopped channels with partial-band interference is investigated. The performance measures considered are channel capacity and cutoff rate. Worst-case partial-band Gaussian noise interference is assumed with the interference independent of the transmitted signal. The capacity and cutoff rate are calculated as a function of the signal-to-noise ratio. We consider soft decision receivers and hard decision receivers with and without side information. Optimal code rates are found for each of the above cases. The required signal-to-noise ratio for reliable communication when codes are used is determined as a function of the code rate.

Coding for Frequency-Hopped Spread-Spectrum Communication with Partial-Band Interference--Part II: Coded Performance

The performance of codes in a frequency-hopped spreadspectrum communication system with partial-band interference is investigated. The performance measure considered is the decoded bit error probability. A simplified interference model and worst-case partial-band Gaussian noise interference model is considered with the interference noise statistically independent of the transmitted signal. We consider soft decision receivers with side information and hard decision receivers with and without side information.

Performance of Reed-Solomon Coded Frequency-Hop Spread-Spectrum Communications in Partial-Band Interference

This paper is concerned with the performance of a Communications system which utilizes frequency-hop spread spectrum, diversity transmission, Reed-Solomon coding, and parallel error-correction and erasure-correction decoding. Both binary signaling and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</tex> -ary orthogonal signaling are considered. The goals are twofold. First, it is desirable to provide good performance in partial-band Gaussian noise interference by use of coding and diversity with an efficient error-correction algorithm. Second, it is necessary to totally neutralize narrow-band interference (regardless of the power level or statistical distribution of the interference) in order to have an effective spread-spectrum system. Through an analysis of the effects of partial-band interference on a frequency-hop spread-spectrum system with diversity, it is shown that the use of ReedSolomon coding with a parallel errors and erasures decoding algorithm accomplishes these goals. The paper also investigates the accuracy of the Chernoff bound as an approximation to the true performance of a frequency-hop spreadspectrum communication system with diversity; side information, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</tex> -ary orthogonal signaling, and Reed-Solomon coding. The performance results presented in the paper are based on analysis and computer evaluation. Approximate results based on the Chernoff bound are also given. It is shown that the Chernoff bound for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</tex> -ary orthogonal signaling gives a very poor approximation for many cases of interest. This is largely due to the looseness of the union bound.