Interference Cancellation Method Research Articles

Joint Optimization of Age of Information and Energy Consumption in NR-V2X System Based on Deep Reinforcement Learning.

As autonomous driving may be the most important application scenario of the next generation, the development of wireless access technologies enabling reliable and low-latency vehicle communication becomes crucial. To address this, 3GPP has developed Vehicle-to-Everything (V2X) specifications based on 5G New Radio (NR) technology, where Mode 2 Side-Link (SL) communication resembles Mode 4 in LTE-V2X, allowing direct communication between vehicles. This supplements SL communication in LTE-V2X and represents the latest advancements in cellular V2X (C-V2X) with the improved performance of NR-V2X. However, in NR-V2X Mode 2, resource collisions still occur and thus degrade the age of information (AOI). Therefore, an interference cancellation method is employed to mitigate this impact by combining NR-V2X with Non-Orthogonal multiple access (NOMA) technology. In NR-V2X, when vehicles select smaller resource reservation intervals (RRIs), higher-frequency transmissions use more energy to reduce AoI. Hence, it is important to jointly considerAoI and communication energy consumption based on NR-V2X communication. Then, we formulate such an optimization problem and employ the Deep Reinforcement Learning (DRL) algorithm to compute the optimal transmission RRI and transmission power for each transmitting vehicle to reduce the energy consumption of each transmitting vehicle and the AoI of each receiving vehicle. Extensive simulations demonstrate the performance of our proposed algorithm.

Time domain turbo equalization based on vector approximate message passing for multiple-input multiple-output underwater acoustic communications.

This paper proposes a high-performance receiver for underwater acoustic communications based on time reversal processing for multiple-input multiple-output (MIMO) systems. The receiver employs the vector approximate message passing (VAMP) algorithm as a soft equalizer in turbo equalization. By performing self-iteration between the inner soft slicer and the inner soft equalizer, the VAMP algorithm achieves near-optimal performance. Furthermore, an iterative channel-estimation-based soft successive interference cancellation method is incorporated to suppress co-channel interference in the MIMO system. Additionally, the introduction of passive time reversal technology can combine multiple channels into a single channel, which greatly reduces the computational complexity of the MIMO system, especially for large MIMO systems. The effectiveness of the proposed receiver is verified using experimental data collected in Songhua Lake, China in 2019. The results demonstrate that the proposed receiver significantly reduces the complexity of the traditional parallel-VAMP receiver without sacrificing performance and outperforms other receivers of the same type. Moreover, our experimental results also verify that the VAMP-turbo outperforms the generalized approximate message passing (GAMP)-turbo in terms of bit error rate and convergence performance.

Accumulation and Elimination: A Hard Decision-Based Multi-User Interference Cancellation Method in Satellite Communication System

With the increasing number of users in the Medium-Orbit (MEO) satellite communication system, multi-access interference (MAI) has become an important factor that restricts the reliability and capacity of the system. Additionally, the low carrier-power-to-noise-density ratio (C/N0) resulting from long-distance transmission poses a significant concern. The parallel interference cancellation (PIC) algorithm, utilized within the paradigm of multi-user detection (MUD), exhibits the capability to effectively mitigate the impact of MAI within the same system. Simultaneously, coherent accumulation serves as a means to substantially enhance the correct detection probability (Pcd) at low C/N0. In this study, a signal acquisition method for multi-user spread spectrum satellite receivers is proposed, which employs interference cancellation and coherent accumulation as its core mechanisms. Furthermore, we introduce a power estimation method based on the outcomes of signal acquisition, which can be integrated into the signal reconstruction module of PIC. Finally, we implement the aforementioned algorithms in both simulation and hardware platforms. Remarkably, we observe that when the interference-to-signal ratio (ISR) caused by MAI equals 20 dB, the improved algorithm attains a maximum Pcd of 0.95 within the high signal-to-noise ratio (SNR) region, closely approaching the theoretical limit for the bit error rate (BER). The experimental results prove the effectiveness and feasibility of the acquisition algorithm. In summary, the enhanced algorithm holds vast potential for widespread implementation in multi-user spread spectrum communication systems.

Recurrent neural networks for enhanced joint channel estimation and interference cancellation in FBMC and OFDM systems: unveiling the potential for 5G networks

FBMC is a pivotal system in 5G, serving as a cornerstone for efficient use of available bandwidth while simultaneously meeting stringent requirements for high spectral efficiency. Notably, FBMC harnesses the power of multicarrier modulation (MC), a good alternative to orthogonal frequency division multiplexing (OFDM) technology that supports fourth-generation (4G) systems. The wireless communications field is full of challenges, the most important of which are channel estimation and interference cancellation, both of which deserve comprehensive study to increase the efficiency of data transmission. In this paper, our investigation takes a deliberate step towards the convergence of two prominent modulation models: OFDM and FBMC. We specifically contrast these modulation techniques with the intricate field of joint channel estimation and interference cancellation (JCEIC). In this research study, we take advantage of recurrent neural networks' (RNNs') efficiency as a vehicular channel to perform precise channel estimation and recovery of uncorrupted transmitted signals, thereby lowering the bit error rate (BER). Our channel estimation for a dual selective channel is based on the thoughtful placement of pilots scattered over the temporal and frequency dimensions, and is further improved by the interference cancellation method of low complexity that was selected. Our JCEIC proposal aims to integrate RNNs carefully, using the output sequences of JCEIC algorithms as useful inputs to this neural architecture. By clearly demonstrating a decrease in BER as compared to traditional approaches, it is evident that the performance of the novel approach is near to that of a perfect channel. Additionally, a comparison of the performance of FBMC and OFDM systems at various signal-to-noise ratios reveals a clear performance divide that favors the former in terms of system efficiency. The BER is restricted by FBMC to a commendable threshold of less than 0.1 at a modest 5 dB, continuing the higher trend started by its improved RNN-based channel estimate. The accuracy of channel estimation is clearly improved by this paradigm shift, and the computing complexity typical of 5G networks is also clearly reduced.

High accurate detection method for aortic valve opening of seismocardiography signals

Accurately detecting the aortic valve opening (AO) peaks of seismocardiography (SCG) is a challenging problem due to interference of other morphological inflection points. In this paper, a high accurate method is proposed to extract AO peaks based solely upon the SCG data. The raw SCG signal is purified by a simple first order interference cancellation method, resulting in a reduced number of modes to be decomposed. The purified SCG signal is then decomposed into a series of quasi-orthogonal modes by successive variational mode decomposition (SVMD) without any prior about the number of modes. Considering the pulsatile nature of the AO signal, a waveform factor criterion is proposed to reconstruct the AO signal based on the pulsatile level of each mode. A seventh power law detector is designed to amplify the AO peak and suppress spurious peaks. The publicly available combined measurement of electrocardiogram (ECG), breathing and seismocardiograms (CEBS) database is exploited to verify the performance of the proposed method. We show that the average sensitivity of our technique is 99.02%, the prediction rate is 99.06%, and the detection accuracy is 98.10%, which is superior to several state-of-the-art methods. In addition, compared with the ECG reference value, the instantaneous heart rate extracted by the proposed method is in good agreement with that of the ECG, e.g., the maximum average absolute error percentage is as low as 2.11 and the maximum average value relative error is about 0.03, further demonstrating that the proposed method can achieve accurate estimates of heart rate with an accelerometer alone.

Interference Cancelation for Coexistence of LoRaWAN With Wireless Power Transfer

Low power wide area networks (LPWANs), which realize long-distance communication with low power consumption, are suitable for wireless sensor networks (WSNs). In particular, long range wide area network (LoRaWAN) has been actively studied in recent years. Since wireless power transfer (WPT) charges the battery of terminals by sending high-frequency signals, it can avoid operational disruption for battery replacement and unnecessitate wiring. However, if it is not well designed, WPT may cause interference to other wireless communication systems using the same frequency band. This paper proposes a simple yet effective WPT interference cancellation method, which is suitable for LoRaWAN, to take a step to move the coexistence of LPWAN and WPT forward. The proposed method estimates the initial phase of the interfering signal by utilizing the packet frame structure of LoRaWAN and removes the interfering signal from the received signal during the signal detection process. Computer simulation results show that the proposed method can achieve almost the same symbol error rate (SER) performance as the system without interference, even under WPT interference.

Joint Receiver Design for Integrated Sensing and Communications

In this letter, we investigate the joint receiver design for integrated sensing and communication (ISAC) systems, where the communication signal and the target echo signal are simultaneously received and processed to achieve a balanced performance between both functionalities. In particular, we proposed two design schemes to solve the joint sensing and communication problem of receive signal processing. The first is based on maximum likelihood (ML) detection, minimum mean squared error (MMSE) estimation and interference cancellation (IC), and the other formulates a tailored MMSE estimator for target estimation that is independent to the detector, which form a Non-IC design. We show that with the structural information of the communication signal taken into account, the Non-IC approach outperforms the IC method and achieves optimal performance. Numerical results are provided to validate the effectiveness of the proposed optimal designs.

Designing FDA Radars Robust to Contaminated Shared Spectra

This paper considers the problem of jointly designing the transmit waveforms and weights for a frequency diverse array (FDA) in a spectrally congested environment in which unintentional spectral interferences exist. Exploiting the properties of the interference signal induced by the processing of the multi-channel mixing and low-pass filtering FDA receiver, the interference covariance matrix structure is derived. With this, the receive weights are formed using the minimum variance distortionless response (MVDR) method for interference cancellation. Owing to the fact that the resulting output signal-to-interference-plus-noise ratio (SINR) is a function of the transmit waveforms and weights, as well as due to the ever-greater competition for the finite available spectrum, a joint design scheme for the FDA transmit weights and the spectrally compatible waveforms is proposed to efficiently use the available spectrum while maintaining a sufficient receive SINR. The performance of the proposed technique is verified using numerical simulations in terms of the achievable SINR, spectral compatiblity, as well as several aspects of the synthesized waveforms.

Simultaneous Transmit and Receive Phased Array System Architecture and Prototype Comprehensive Verification

In the future multi-functional detection sensing and communication integrated systems, as well as 5G/6G systems, simultaneous transmit and receive technology, as an important key technology, is an important supporting measure to achieve the simultaneous work of different functions. Looking at the problem of strong self-interference in the simultaneous multi-function application of a phased array transceiver, this paper presents the integrated cancellation architecture and corresponding method of integrated transmission domain, RF domain and digital domain, and completes principle experiment verification of interference suppression and elimination by constructing the principle experiment system. Experimental results show that in the actual hardware system 0.5 db amplitude quantification and 6-bit phase quantization control conditions, through joint using passive and active beam transfer of the domain space optimization form, at the same time in the digital domain application of the adaptive system identification interference cancellation method for further interference cancellation, above 150 dB for interference suppression can be achieved. This research will provide a certain reference for the application of simultaneous transceiver technology in future 5G/6G phased array antenna systems.

A TDMA approach for OFDM-based multiuser RadCom systems

This paper is focused on the multiuser implementation of fusion of radar and communication (RadCom) in internet-of-vehicles (IoV) scenarios. Traditional time-division multiple access (TDMA) technology degrades the velocity detection performance of orthogonal frequency-division multiplexing (OFDM)-based RadCom systems. We propose a new TDMA approach for OFDM-based RadCom systems, where multiuser communication and radar detection are completed synchronously. We consider a continuous-wave TDMA OFDM structure in which random user data or Zadoff-Chu (ZC) sequences are transmitted in one symbol duration to ensure detection performance. As an application of interference cancellation method, user data demodulation and environment sensing can be simultaneously accomplished by our proposed approach. We carry out numerical evaluation and show wireless communication and radar detection performance over the continuous-wave TDMA OFDM-based RadCom approach.

A Linear Near-Field Interference Cancellation Method Based on Deconvolved Conventional Beamformer Using Fresnel Approximation

In underwater acoustic detection using towed arrays, the in-band radiation noise of the tow-ship generates significant interference. In this article, a high-resolution spatial filter based on the deconvolved conventional beamformer (dCv) is proposed to mitigate the impact of this noise on the detection on the beam of interest. The tow-ship interference is near field, thus, the dCv cannot be applied directly as the point spread function is shift variant. In this work, a solution to this problem involving the Fresnel approximation is developed. It is demonstrated analytically that the Fresnel approximation is not sensitive to the accuracy of the estimation of the interference range, and its applicability depends on the arrival angle of the interference. Experimental results show that the linearity of the dCv spatial filter ensures that the amplitude and phase of the array signal can be retrieved with no distortion, which is critical for acoustic detection.

On the outage performance of multi-user NOMA system with adaptive SIC

The performance of non-orthogonal multiple-access (NOMA) is significantly determined by the successive interference cancellation (SIC) technique. However, the interference redundancy can happen during the NOMA receiver performing SIC. To tackle this issue, this paper proposes a novel adaptive successive interference cancellation (ASIC) method. Specifically, the decoding error is considered as interference during the SIC process, and an adaptive filter with various weights is introduced for detection error mitigation. For the multi-user downlink NOMA system, the outage probability is analyzed under conventional and the proposed SIC methods. Simulation results verify our analysis, which also demonstrate the superiority of the proposed ASIC method.

Modeling Target Detection and Performance Analysis of Electronic Countermeasures for Phased Radar

Interference is a key factor in radar return misdetection. Strong interference might make it difficult to detect the signal or targets. When interference occurs in the sidelobes of the antenna pattern, Sidelobe Cancellation (SLC) and Sidelobe Blanking are two unique solutions to solve this problem (SLB). Aside from this approach, the probability of false alert and likelihood of detection are the most essential parameters in radar. The chance of a false alarm for any radar system should be minimal, and as a result, the probability of detection should be high. There are several interference cancellation strategies in the literature that are used to sustain consistent false alarms regardless of the clutter environment. With the necessity for interference cancellation methods and the constant false alarm rate (CFAR), the Maisel SLC algorithm has been modified to create a new algorithm for recognizing targets in the presence of severe interference. The received radar returns and interference are simulated as non-stationary in this approach, and sidelobe interference is cancelled using an adaptive algorithm. By comparing the performance of adaptive algorithms, simulation results are shown. In a severe clutter situation, the simulation results demonstrate a considerable increase in target recognition and signal to noise ratio when compared to the previous technique.

BER performance analysis of asynchronous NOMA with arbitrary phase offset

An asynchronous transmission scenario for non-orthogonal multiple access (NOMA) user signals with arbitrary phase offset is investigated in this paper. To improve the system performance in the user power-balanced conditions, we adopt a synthetic detection method at the receiver, i.e., the jointly optimal maximal likelihood detection aided triangular successive interference cancellation (JO ML-TSIC) method. Analytical bit error rate (BER) solutions are obtained for a two-user case with the optimal, intentional one-half symbol period time delay implemented between the user signals. Furthermore, closed-form BER solutions for the case using the triangular successive interference cancellation (TSIC) detection method are also derived for comparisons. Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation (SIC) receiver in all the conditions concerned. The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.

Non-linear photonic loop mirror based co-site interference canceller

Full duplex-in band (FDIB) is a well-established solution for increasing the data rate and spreading the link range for future communication systems. FDIB systems need no additional bandwidth requirement. However, they are confronted with a major interference challenge on the same site, called co-site interference (CSI). Long-established co-site interference cancellation (CSIC) methods achieve a cancellation depth upto 35 dB, conversely it has space containments, manufacturing imperfections, induces noise penalties and limits isolation bandwidth. To overcome these problems, RF photonic CSIC methods have been developed, which have produced 30 dB wide-band interference suppression. They also increase bandwidth, have a flexible structure, minimize losses and prevent periodic power fading. But these systems have a problem of inherent DC drift, low maintenance of coherence, and low isolation at low transmission power. Thus, there is a high need for photonic CSIC designs of FDIB systems that operate over wider bandwidths and at higher transmission powers. Here, a newfangled CSIC system based on a non-linear photonic loop and frequency down-conversion is proposed. It shows excellent CSIC suppression of greater than 61 dB, for a single frequency signal of interest (SOI) with maximum RF power of 13 dBm. Without frequency down-conversion, the system maintains an average cancellation depth of 62.541 dB for single frequency SOI. After frequency down conversion, the system maintains an average cancellation depth of 61.208 dB for narrow band SOI. The system attains 18% error vector magnitude at −20 dB RF output power, which confirms the comprehensive quality of the system.

A new adaptive co-site broadband interference cancellation method with auxiliary channel

With the boom of the communication systems on some independent platforms (such as satellites, space stations, airplanes, vessels), co-site interference is becoming prominent. The adaptive interference cancellation method has been adopted to solve the co-site interference problem. But the broadband interference cancellation performance of traditional Adaptive Co-site Interference Cancellation System (ACICS) with large delay mismatching and antenna sway is relatively poor. This study put forward an Adaptive Co-site Broadband Interference Cancellation System With Two Auxiliary Channels (ACBICS-2A). The system model was established, and the steady state weights and Interference Cancellation Ratio (ICR) were deduced by solving a time-varying differential equation. The relationship of ICR, system gain, modulation factor, interference signal bandwidth and delay mismatching degree was acquired through an in-depth analysis. Compared with traditional adaptive interference cancellation system, the proposed ACBICS-2A can improve broadband interference cancellation ability remarkably with large delay mismatching and antenna sway for the effect of auxiliary channel. The maximum improved ICR is more than 25dB. Finally, the theoretical and simulation results were verified by experiments.

CNN-Based Inter-Band Interference Cancellation for 100Gbit/s/λ Non-Orthogonal m-CAP in Fronthaul

To improve the spectral efficiency (SE) of next-generation-fronthaul-interface-based (NGFI) mobile fronthaul (FH) network, we present a novel inter-band interference (IBI) cancellation method based on convolutional neural network (CNN) in non-orthogonal multiband CAP (NO-m-CAP) system. As a proof of concept demonstration, a NO-4-CAP 100Gb/s/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> NGFI-II data transmission experiment is carried out, which shows 15% SE improvement with the proposed CNN-based IBI canceller assuming a 7% HD-FEC limit. Being more straightforward and practical, the proposed CNN-based IBI canceller with lower complexity could offer more power budget and promise more compression ratio compared to our previously proposed ICA-based (Independent Component Analysis) method.

AMCC nonlinear baseband superimposition and extraction aided by proposed interference cancellation for WDM-PON used in 5G mobile fronthaul.

As the demand for mobile Internet capacity explodes, the research on fifth-generation (5G) mobile communication systems has gradually deepened, which has stringent requirements for latency and transmission capacity, especially in the section called mobile fronthaul (MFH). Wavelength division multiplexing passive optical network (WDM-PON) is an attractive technology for 5G MFH which requires an auxiliary management and control channel (AMCC) to achieve efficient network deployment. In previous studies, more research has been done on AMCC superimposition methods and transmission performance on 10 Gbps WDN-PON systems, and the role of AMCC in wavelength management has been studied at the system level. In this paper, we realize non-linear baseband modulation of AMCC signals up to 20 Mbps in a single wavelength 25-Gbps PON system through the distributed feed-back laser and Mach-Zehnder modulator. At the receiving end, we propose a low-complexity interference cancellation method to suppress the interference caused by WDM-PON signals and significantly reduce the bit error rate of AMCC signals. The method realizes a simplified scheme to reconstruct the PON signals by analyzing the characteristics of nonlinear modulation and the reconstructed signals can be applied to the original AMCC signals through filtering and subtraction to eliminate interference. These operations have low complexity and can be easily implemented by analog circuits, thus making it an effective way to improve the quality of AMCC signals. With the help of the proposed method, AMCC transmission at 20 Mbps can be achieved with different modulation depths, which is very promising for 5G MFH.

A Real-Time Digital Self Interference Cancellation Method for In-Band Full-Duplex Underwater Acoustic Communication Based on Improved VSS-LMS Algorithm

Theoretically, the spectral efficiency of in-band full-duplex underwater acoustic communications (IBFD-UWAC) is twice that of a half-duplex one. However, the actual achievable spectral efficiency of IBFD-UWAC is determined by the performance of the self-interference cancellation (SIC). In addition, the hostile underwater environment poses a challenge to the tracking performance of the SIC due to its complexity and variability. In this paper, we propose a digital SIC method based on the improved variable step-size least mean square (IVSS-LMS) algorithm where we modify the step-size adjustment criterion in the classical LMS filter and establishes a nonlinear relationship with the Sigmoid function to control the step-size using the instantaneous state error, thus improving the robustness and tracking performance of IVSS-LMS. Hardware-in-loop simulation (HLS) based on Simulink® platform verifies the real-time implementability and effectiveness of the proposed IVSS-LMS algorithm. Furthermore, the sea trial results show that the digital SIC method based on the proposed algorithm can be implemented in real-time and the convergence speed, and steady-state performance are significantly improved.

EMD and Wavelet Methods for Interference Cancellation in Quadrupole Resonance Detection

EMD and Wavelet Methods for Interference Cancellation in Quadrupole Resonance Detection