Tone Interference Research Articles

Not fully remembered, but not forgotten: interfering sounds worsen but do not eliminate the representation of pitch in working memory.

Recent research has begun measuring auditory working memory with a continuous adjustment task in which listeners adjust attributes of a sound to match a stimulus presented earlier. This approach captures auditory memory's continuous nature better than standard change detection paradigms that collect binary ("same or different") memory measurements. In two experiments, we assessed the impact of different interference stimuli (multitone complexes vs. white noise vs. silence) on the precision and accuracy of participants' reproductions of pitch from memory. Participants were presented with a target multitone complex stimulus followed by eight successive interference signals. Across trials, these signals alternated between additional multitone complexes, randomly generated white noise samples, or (in Experiment 2) silence. This was followed by a response period where participants adjusted the pitch of a response stimulus using a MIDI touchpad to match the target. Experiment 1 found a significant effect of interference type on performance, with tone interference signals producing the greatest impairments to participants' accuracy and precision compared to white noise. Interestingly, it also found a compression in the participants' responses, with overestimations of low-frequency targets and underestimations for high-frequency targets. Experiment 2 replicated results from Experiment 1, with an additional silence condition showing the best performance, suggesting that non-tonal signals also generate interference. In general, results support a shared resource model of working memory with a limited capacity that can be flexibly allocated to hold items in memory with varying levels of fidelity. Interference does not appear to knock items out of a fixed precision slot, but rather robs a portion of capacity from stored items.

Interference suppression algorithm for wireless communication network based on joint estimation

When the wireless communication network is interfered, the communication effect will be affected. In order to improve the interference signal processing effect and the identification accuracy of the interference signal, a wireless communication network interference suppression algorithm based on joint estimation is proposed. Using the deep learning method to identify the interference signal, obtain the effective interference signal of wireless communication network, improve the accuracy of interference signal identification, and track and parameter modulation the identified signal; The node model of wireless communication network is established, and the joint estimation method is used to suppress the interference signal for the nodes in the model. The interference suppression of wireless communication network is realized through the state estimation of single tone interference and narrowband interference. The experimental results show that the proposed algorithm has a high accuracy of interference signal recognition, the highest value reaches 98%, and the wireless communication data packet loss rate is low, the highest value is only 0.37, which verifies its interference suppression effect.

Analysis of Phase-Locked Loop in the Presence of Tone Interference and Noise

Analysis of Phase-Locked Loop in the Presence of Tone Interference and Noise

Performance of UWB communication systems in presence of perfect/imperfect power control MAI and IEEE802.11a interference

This paper evaluates the bit error rate performance of Impulse Radio-Ultra-Wideband (IR-UWB) communication system under the impact of both multiple access and narrowband interferences operating. The Narrowband Interference (NBI) signal is modelled as the IEEE802.11a orthogonal frequency division multiplexing-based wireless local area network signal, which can be approximated by the sum of independent asynchronous tone interferers with arbitrary frequencies. Multiple Access Interference (MAI) is assumed a zero mean Gaussian process, where it has been investigated in both perfect and imperfect power control scenarios. The bit error rate performance is evaluated in three different channel models: ideal channel model (additive white Gaussian noise channel), Nakagami-m multipath fading channel model and the IEEE802.15.3a UWB channel model. It will be shown that the performance of a UWB system is severely degraded due to the presence of both types of interference, yet the NBI has more impact on the performance of UWB communication systems compared to the multiple access one.

DS-UWB pulse design in IEEE802.15.3a multipath fading channel for cognitive radio applications

This paper presents a novel spectrum shaping technique in direct sequence ultra-wideband (DS-UWB) communication systems. This proposed pulse introduces spectral nulls to limit the interference impact of high power coexisting narrowband signals and to elevate the applications of cognitive radio. The idea depends on the addition and subtraction of several UWB Gaussian derivative pulses in order to design a new pulse that has spectral null at the operating frequency of the narrowband interference (NBI) signal. The use of the Gaussian derivative ensures that the UWB spectrum mask established by the Federal Communications Commission (FCC) is met. The NBI signals are modelled as either the wireless local area network (WLAN) IEEE802.11n which operates in the 5 GHz frequency band or multi tone signals. The power spectral density of the proposed transmitted UWB pulse is derived analytically. The bit error rate performance of the proposed pulse is derived in the multi-path IEEE802.15.3a UWB fading channel models and validated with simulations. Results show that the impact of either the IEEE802.11n interference signal or the multi tone interference signals can be effectively suppressed by transmitting and matched filtering the new pulse with a single or multiple spectral nulls at the interference operating frequencies.

Fast Synchrophasor Estimation by Means of Frequency-Domain and Time-Domain Algorithms

This paper presents a performance comparison of two classes of synchrophasor estimators recently proposed in the literature, i.e., the frequency-domain algorithms known as interpolated discrete Fourier transform (IpDFT), and the time-domain algorithms based on the weighted least squares (WLSs) approach. The analysis is focused on fast phasor estimation only and it is performed under steady-state, dynamic, and transient conditions, when the length of the observation interval is equal to one or two nominal cycles of the acquired electric waveform. The considered testing conditions include not only the worst-case scenarios specified in the IEEE Standard C37.118.1-2011, but they also combine the effect of static and dynamic disturbances. As accuracy performance parameters, the total vector error as well as the amplitude and phase estimation errors are considered and evaluated. Estimator responsiveness is analyzed instead in terms of response times, when amplitude or phase steps occur. The preferable one- and two-cycles IpDFT and WLS algorithms are first determined by choosing the windows and the number of Taylor's series terms (in the WLS case only) assuring the best accuracy. It is shown that, when the time-domain approach is considered and one-cycle or two-cycle intervals are observed, the best accuracy is achieved by the WLS algorithm based on the rectangular window or the two-term one-cycle maximum image tone interference rejection (MIR) window, respectively. Conversely, when the frequency-domain approach is adopted, the best accuracy is achieved by the IpDFT-based on the MIR window related to the observed interval length. The estimates produced by the selected WLS and IpDFT algorithms are then compared against the boundaries specified in the Standard IEEE C37.118.1-2011 for P-and M-class compliance. During the discussion, advantages and disadvantages of both time-domain and frequency-domain approaches are highlighted.

Adaptive narrowband interference mitigation by designing UWB waveforms based on radial basis function neural networks

In order to mitigate the mutual interference between ultra-wideband (UWB) impulse radio and other existing wireless systems, a novel adaptive interference-avoiding UWB pulse, in the context of the appealing cognitive radio, is presented based on the radial basis function neural networks. Theoretical and implementation architecture for UWB pulse generator is addressed. Transmission performance in the presence of narrowband interference including tone interference is comprehensively analyzed. The presented generator can adaptively change the spectrum shape of UWB signals according to the authorized users’ working states, and hence the mutual interference between UWB and other systems sharing the frequency bands can efficiently be avoided. The critical performance indication parameters, such as the SNR, SIR, and BER of UWB communication links, are also derived. Performance evaluations and comparisons between the proposed scheme and other pulse optimization methods have been provided based on the extensive numerical simulations. It is demonstrated that the presented pulse can indeed achieve much superior performance in terms of either single-link BER or anti-jamming capability.

Capacity Analysis and Pilot-Data Power Allocation for MIMO-OFDM With Transmitter and Receiver IQ Imbalances and Residual Carrier Frequency Offset

We analyze the ergodic capacity and capacity bound of a multiple-input–multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) system suffering from frequency-selective in-phase and quadrature-phase (IQ) imbalances along with residual carrier frequency offset (CFO). In the literature, capacity analysis of systems with IQ imbalance has been done only for the single antenna case and has considered either frequency-flat IQ imbalances at both transmitter and receiver sides without CFO or only receiver-side IQ imbalances with CFO. Additionally, these works dealt with IQ imbalance by treating the mirror tone interference as an additional source of noise, which is not optimal. In this paper, we consider a generalized system model that includes a multiantenna system with frequency-selective IQ imbalances at both the transmitter and the receiver sides, in addition to the presence of CFO, and perform capacity analysis considering joint detection of the signal and its self-interference. In addition, for the imperfect channel estimation case, existing works in the literature optimize for pilot spacings and pilot designs. Pilot-data power allocation is an additional degree of freedom that is available to further optimize the system and has not been addressed before. Therefore, we analyze the pilot-data power allocation that maximizes the capacity bound and obtain a closed-form solution for the optimal power allocation at high signal-to-noise ratio (SNR) regime. We then study how the IQ imbalance and residual CFO severity affect capacity, symbol error rate (SER), and capacity bound maximizing power allocation. Finally, we derive the optimal power allocation when the channel is slow varying and remains constant over a block of several OFDM symbols. The derived results are validated through Monte Carlo simulations.

Performance Analysis and Optimization of $\hbox{T}_{\rm c}$-DTR IR-UWB Receivers Over Multipath Fading Channels With Tone Interference

In this paper, we analyze the performance of a particular class of transmitted-reference receivers for impulse radio ultrawideband communication systems, which is called chip-time differential transmitted-reference ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{T}_{\rm c}$</tex></formula> -DTR). The analysis aims at investigating the robustness of this receiver to single-tone and multitone narrowband interference (NBI) and comparing its performance with other noncoherent receivers that are proposed in the literature. It is shown that the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{T}_{\rm c}$</tex></formula> -DTR scheme provides more degrees of freedom for performance optimization and that it is inherently more robust to NBI than other noncoherent receivers. More specifically, it is analytically proved that the performance improvement is due to the chip-time-level differential encoding/decoding of the direct sequence (DS) code and to an adequate design of DS code and average pulse repetition time. The analysis encompasses performance metrics that are useful for both data detection (i.e., average bit error probability) and timing acquisition (i.e., false-alarm probability <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{P}_{\rm fa}$</tex></formula> and detection probability <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{P}_{\rm d}$</tex></formula> ). Moving from the proposed semianalytical framework, the optimal code design and system parameters are derived, and it is highlighted that the same optimization criteria can be applied to all the performance metrics considered in this paper. In addition, analytical frameworks and theoretical findings are substantiated through Monte Carlo simulations.

Interference Impact on the Performance of UWB Communication Systems

This paper evaluates the bit error rate performance of a ultra-wideband (UWB) communication system under the impact of both multiple access and narrowband interferences operating in additive white Gaussian noise (AWGN) channels. The narrowband interference (NBI) signal is modeled as the IEEE802.11a signal, which can be approximated by the sum of independent asynchronous tone interferers with arbitrary frequencies. Multiple access interference is assumed a zero mean Gaussian process, where it has been investigated in both perfect and imperfect power control scenarios. It will be shown that the performance of a UWB system is severely deteriorated due to the presence of both types of interference, yet the NBI has more impact on the performance of UWB communication systems compared to the multiple access one.

Multiple tone interference of multicarrier frequency-hopping BPSK system for a Rayleigh fading channel with channel estimation errors

In this paper, we analyze the error probability performance of an uncoded multicarrier frequency-hopping coherent binary phase-shift keying (MC-FH/BPSK) signal transmitted over a Rayleigh fading channel with multitone interference (MTI) and channel estimation errors. The channel estimation errors are modeled as Gaussian random variables. The performance in presence of worst case MTI is evaluated as a function of signal to noise ratio (SNR), signal to jamming ratio, and channel estimation errors. The effect of channel estimation errors on the error probability performance is investigated in presence and absence of MTI. It is shown, from the analytical results that when channel estimation errors are not neglected, the asymptotic error probability performance for high SNR exhibits an error floor even in the absence of MTI. Worst case MTI causes large increase in this error floor. It is also shown that increasing the subband order L enhances the system performance against multitone interference.

On the cumulative distribution function of quadratic-form receivers over generalized fading channels with tone interference

In this paper, we develop a general and unified framework for estimating the Cumulative Distribution Function (CDF) of quadratic-form receivers. The expression of the CDF that we finally achieve takes on the form of a single integral with finite limits and integrand composed of elementary functions, which can be readily integrated using standard techniques. In particular, the specific contribution of this manuscript is twofold: i) we present a comprehensive framework for the analysis of multi-channel reception systems using either non-coherent or differentially-coherent detectors, diversity systems with practical (i.e., noisy) channel estimators, and Transmitted-Reference (TR) receiver architectures working in frequency-selective fading channels, and ii) we show that the framework can be efficiently used for performance assessment of wireless systems over generalized fading channels and, under mild assumptions, over generalized fading channels further impaired by in-band multi-tone interference.

Tone interference suppression in DS-SS systems with modified DFT

The performance of traditional interference excision methods based on the discrete Fourier transform (DFT) in direct sequence spread spectrum (DS-SS) systems varies significantly with the frequency of the interference because the DFT of the interference becomes more dispersive with the increase of grid biases in the DFT operation. This paper presents a new excision method using modified DFT (MDFT) with an estimated grid bias. Minimum dispersion of the interference is achieved in the MDFT domain. Both theoretical analysis and experimental simulation are presented to show that the interference can be excised with a minimum distortion of the desired signal in a large range of interference-to-signal ratio.

Narrowband Interference Suppression in Frequency-Hopping Spread Spectrum Using Undecimated Wavelet Packet Transform

Suppression of narrowband interference in frequency-hopping spread spectrum (FH-SS) systems is treated in this paper. First, we analyze the effect of continuous-wave tone interference in noncoherent binary frequency-shift keying (BFSK) signaling with FH-SS. Based on this analysis, a new receiver for FH-SS systems is proposed, including a transform-domain interference suppression module. The algorithm is executed in two steps: 1) interference detection and 2) signal reconstruction. The novelty of this suppression algorithm is the combination of the undecimated wavelet packet transform with frequency shifts of the received signal to center the narrowband interference in a subband. Once the subband that contains the interference has been determined, the algorithm removes this subband and then reconstructs the signal. The performance of this receiver has been evaluated in a variety of situations with different types of narrowband interference. The results obtained show the improvement of the proposed receiver in comparison to the traditional FH-SS receiver.

Narrowband interference suppression in chaos-based communications based on set-membership estimation

This paper presents the set-membership estimation for narrowband interference (NBI) suppression in chaos-based communications. The proposed NBI suppression methods under known or unknown model parameters of interference signals are derived in terms of the optimal bounding ellipsoid criteria and the bounded property of chaotic carriers, respectively. Compared to the mean phase space volume (MPSV) based Kalman filtering and the recursive least square (RLS) algorithms, the proposed NBI suppression method estimates interference signals using only a few observations with the selective updating features, so that the computation is effectively reduced. Simulations results on AR and single tone interference suppression in chaotic parameter modulation (CPM) and differential chaotic shift keying (DCSK) communication systems show that the proposed NBI suppression methods can efficiently eliminate the narrowband interference signal in CPM and DCSK communication systems, and the computation is smaller than that of MPSV-based Kalman filtering and RLS algorithms.

Transmitter-Side Multipath Preprocessing for Pulsed UWB Systems Considering Pulse Overlapping and Narrow-Band Interference

We analyze a prerake diversity combining scheme for pulsed ultrawideband systems to shift signal processing needs from the receiver to the transmitter. We consider the realistic case that received pulses carrying the same transmitted symbol could overlap with one another in optimizing the prerake scheme based on zero-forcing and eigenanalysis techniques. We show that in the presence of interpulse interference caused by pulse overlapping, the optimum prerake combining scheme in the sense of maximizing the received signal-to-noise ratio derived by using the eigenanalysis technique performs the same as a conventional rake with maximal ratio combining. We also analyze the different behaviors of prerake and rake schemes in the presence of tone interferers and provide numerical results to validate the conclusions in the presence of in-band-modulated interferers. We find that when the number of narrow-band interference (NBI) signals is small, the prerake scheme outperforms the rake scheme; as the number of NBI sources increases, however, this performance gap reduces.

Error Rate Analysis for Coded Multicarrier Systems Over Quasi-Static Fading Channels

Several recent standards such as IEEE 802.11a/g, IEEE 802.16, and ECMA Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) for high data-rate Ultra-Wideband (UWB), employ bit-interleaved convolutionally-coded multicarrier modulation over quasi-static fading channels. Motivated by the lack of appropriate error rate analysis techniques for this popular type of system and channel model, we present two novel analytical methods for bit error rate (BER) estimation of coded multicarrier systems operating over frequency-selective quasi-static channels with non-ideal interleaving. In the first method, the approximate performance of the system is calculated for each realization of the channel, which is suitable for obtaining the outage BER performance (a common performance measure for e.g. MB-OFDM systems). The second method assumes Rayleigh distributed frequency-domain subcarrier channel gains and knowledge of their correlation matrix, and can be used to directly obtain the average BER performance. Both methods are applicable to convolutionally-coded interleaved multicarrier systems employing Quadrature Amplitude Modulation (QAM), and are also able to account for narrowband interference (modeled as a sum of tone interferers). To illustrate the application of the proposed analysis, both methods are used to study the performance of a tone-interference-impaired MB-OFDM system.

Error Rate Analysis for Coded Multicarrier Systems Over Quasi-Static Fading Channels

Several recent standards such as IEEE 802.11a/g, IEEE 802.16, and European Computer Manufacturers Association (ECMA) multiband orthogonal frequency division multiplexing (MB-OFDM) for high data-rate ultra-wideband (UWB), employ bit-interleaved convolutionally coded multicarrier modulation over quasi-static fading channels. Motivated by the lack of appropriate error rate analysis techniques for this popular type of system and channel model, we present two novel analytical methods for bit error rate (BER) estimation of coded multicarrier systems operating over frequency-selective quasi-static channels with nonideal interleaving. In the first method, the approximate performance of the system is calculated for each realization of the channel, which is suitable for obtaining the outage BER performance (a common performance measure, for e.g., MB-OFDM systems). The second method assumes Rayleigh distributed frequency-domain subcarrier channel gains and knowledge of their correlation matrix, and can be used to directly obtain the average BER performance. Both methods are applicable to convolutionally coded interleaved multicarrier systems employing quadrature amplitude modulation (QAM), and are also able to account for narrowband interference (modeled as a sum of tone interferers). To illustrate the application of the proposed analysis, both methods are used to study the performance of a tone-interference-impaired MB-OFDM system.

Performance Analysis for OFDMA in the Presence of Tone Interference

Space-frequency coded (SFC) orthogonal frequency-division multiple access (OFDMA) is considered in the presence of multitone (MT) interference. Analytical expressions for the bit-error probability (BEP) are derived for OFDMA with SFC in a frequency-selective fading environment. It is shown that SFC increases the resistance of OFDMA against the MT interference and reduces BEP considerably

Analysis of UWB Interference to MPSK Narrowband Receivers

This paper studies the in-band interference of time-hopping spread spectrum (TH-SS) ultra-wideband (UWB) signals to narrowband receivers. Based on the analysis of general power spectral density (PSD) of TH-SS UWB signal, the interference of UWB signal is partitioned into two parts: (1) additive white Gaussian noise interference, and (2) jamming tone interference. Following this framework, a novel analytical symbol error rate (SER) evaluation method for binary phase-shift keying (BPSK) and M-ary phase-shift keying (MPSK) signals subject to UWB interferences is proposed and corresponding simulation results are demonstrated. It is shown that as the number of in-band jamming tones increases, the UWB interference effect tends to be closer to the effect of the equivalent Gaussian noise. When there is only one UWB tone interferer within the narrowband receiver bandwidth, and when the signal-to-interference-and-noise ratio is higher than a certain value, the narrowband symbol error rate decreases as the relative tone power portion in the overall interference and noise power increases.