Adjacent Channel Interference Research Articles

Analyzing correlation with BER: Constellation diagrams across various modulation modes and FDM/OFDM

Over the last two decades, owing to rapid advancements in digital signal processing and integrated circuit technology, Frequency Division Multiplexing (FDM) and Orthogonal Frequency Division Multiplexing (OFDM) have emerged as pivotal technologies for wireless multimedia communication. Research reveals that coupling OFDM with diverse modulation modes aids in mitigating the Bit Error Rate (BER) during transmission. Nonetheless, a comprehensive elucidation remains absent regarding the interplay between constellation diagrams and BER, as well as the correlation between FDM and BER. Thus, the primary focus of this research is to dissect the correlation between BER and constellation diagrams for distinct modulation methodologies, while also scrutinizing the impact of FDM on BER. The research methodology adopted herein entails two main steps: First, gathering papers pertinent to constellation diagrams, BER, FDM, and OFDM technology. Second, leveraging survey and literature analysis methodologies for thorough examination. The findings highlight that diverse constellation diagram designs yield disparate BER outcomes post demodulation. Foremost among the influential factors on FDM and OFDM technology BER are distinct Inter-Carrier Interference (ICI) patterns and the quantity of subcarriers stemming from signal wave side lobes. To address the BER challenge, a prospective avenue involves refining the selection of constellation diagram styles for demodulation, leveraging an understanding of constellation diagram traits. Furthermore, future research endeavors should delve deeply into co-channel interference and adjacent channel interference to contribute effectively towards BER reduction and augmenting channel reliability.

Single-Cycle Pulse Signal Recognition Based on One-Dimensional Deep Convolutional Neural Network

Pulse signals carry comprehensive information regarding human cardiovascular physiology and pathology, providing a noninvasive and continuous method to assess cardiovascular health status in blood pressure monitoring. The blood pressure measurement method based on the pulse signal needs to extract the features of the single-cycle pulse signal, while the pulse signal pertains to the weak physiological signal of body surface. The acquisition process is susceptible to various factors leading to abnormal cycles, especially adjacent channel interference, affecting the subsequent feature extraction. To address this problem, this paper conducts an analysis of the formation mechanism of adjacent channel interference and proposes a single-cycle pulse signal recognition algorithm based on a one-dimensional deep convolutional neural network (1D-CNN) model. Radial pulse signals were collected from 150 subjects by pulse bracelet, and a dataset comprising 3446 single-cycle signals was extracted in total after denoising, single-cycle segmentation, and standardized preprocessing. The 1D-CNN model is trained to classify input signals into three categories: effective pulse signals, distortion, and interference signals. This classification is achieved by evaluating the waveform morphology of the signals within a single cycle. The results show that the overall classification accuracy of the algorithm on the test set is 98.26%, in which the classification accuracy of pulse waves is 99.8%, indicating that it can effectively recognize single-cycle pulse waves, which lays the foundation for subsequent continuous blood pressure measurement.

An Integrated Orthogonal Frequency-Division Multiplexing Chirp Waveform Processing Method for Joint Radar and Communication Based on Low-Density Parity-Check Coding and Channel Estimation

With the advancement of information technology construction, the integration of radar and communication represents a crucial technological evolution. Driven by the research boom of integrated sensing and communications (ISACs), some scholars have proposed utilizing orthogonal frequency-division multiplexing (OFDM) to separately modulate radar and communication signals. However, the OFDM symbols in this paper incorporate a cyclic prefix (CP) and a virtual carrier (VC) instead of zero padding (ZP). This approach mitigates out-of-band power caused by ZP, in addition to reducing adjacent channel interference (ACI). In addition, we introduce low-density parity-check (LDPC) and use an improved normalized min-sum algorithm (NMSA) in decoding. The enhanced decoding efficiency and minimized system errors render the proposed waveform more suitable for complex environments. In terms of signal processing methods, this paper continues to use radar signals as a priori information to participate in channel estimation. Further, we consider the symbol timing offset (STO) and carrier frequency offset (CFO) issues. In order to obtain more reliable data, we use the minimum mean-square error (MMSE) estimation based on the discrete Fourier transform (DFT) to evaluate the channel. Simulation experiments verify that the system we propose not only realizes the transmission and detection functions but also improves the performance index of the integrated signal, such as the bit error rate (BER) of 7 × 10−5, the peak side lobe ratio (PSLR) of −13.81 dB, and the integrated side lobe ratio (ISLR) of −8.98 dB at a signal-to-noise ratio (SNR) of 10 dB.

Analysis of Possible Interference Effects Minimization in IEEE 802.11ax Network by Partial Allocation of Resource Units

Statement of the problem: one of the main tasks in IEEE 802.11 networks planning is adjacent channel interference mitigation. The purpose of the work is to synthesize a model and analyze the possibility of adjacent channel effects minimization by partial allocation of OFDMA resource units allocation. Methods used: mathematical analysis methods and spectrum modeling. Novelty: in contrast to the existing approaches, quantative estimations of data rate gain has been calculated and a corresponding step-by-step method has been proposed. Result: in this paper an analysis of partial allocation of resourve units within IEEE 802.11ax channel has been carried out. A model of the adjacent channel interference has been proposed, where signal to noise ratio is estimated via spectrum calculation of target and interferer signals. The model parameters range is estimated which corresponds to the gain of total multi user data rate gain in comparison to full target channel resource units utilization. Theoretical and practical relevance: method may be used to additional increase of total data rate in multi user channel operation mode in case of IEEE 802.11 networks interference presence.

Evaluating the level of inteference in UMTS/LTE heterogeneous network system

<p>The study evaluated interference in a dense heterogeneous network using third-generation universal mobile telecommunication systems (UMTS) and fourth-generation long term evolution (LTE) networks LTE. The UMTs/LTE heterogeneous network determines the level of interference when the two communication systems coexist and how to improve the network by migrating from UMTs to LTE, which has a faster download speed and larger capacity. Techno lite 8 on third generation (3G) and Infinix Pro 6 on fourth generation (4G) were used to measure network the received signal strength (RSS) during site investigation. UE interference was detected and traced using a spectrum analyzer. UMTS and LTE path loss exponents are 2.6 and 3.2. Shannon's capacity theorem calculated LTE and UMTS capacity. When signal to interference and noise ratio (SINR) was used as a quality of service (QoS) indicator, MATLAB channel capacity plots did not match Shannon's due to neighboring interference. UMTS had an R2 of 0.54 and LTE 0.57 for the Shannon channel capacity equation. Adjacent channel interference (ACI) user devices reduce network capacity, lowering QoS for other customers.</p>

Performance Analysis of Coordinated Interference Mitigation Approach for Automotive Radar

Millimeter automotive radar has great potential in Advanced Driver Assistance Systems (ADAS) to enable safety features such as adaptive cruise control and collision avoidance. However, with widely deployment of millimeter radars on vehicles, the risk of radar mutual interference becomes a major factor limiting the high performance of radar detection. In this paper, we analyze the mutual interference among multiple Frequency Modulated Continuous Wave (FMCW) radars. On one hand, we study the interference in detail by considering co-channel interference and adjacent channel interference simultaneously. Besides, the co-channel interference is analyzed by employing stochastic geometry model while the adjacent channel interference is assessed by the deterministic analysis method. On the other hand, we propose a Time-Frequency Division Multiple Access (TFDMA) scheme to mitigate the interference in a coordinated manner and evaluate it in terms of mitigation delay, the probability of interference, effective detectable density, maximum number of interference-free radar, and control signaling overhead. Finally, we study the power allocation strategy to enable the effectiveness of the coordinated interference mitigation approach based on the interference analysis. Simulation results verify the proposed framework for interference analysis by employing Monte Carlo method, and the performance improvement of the coordinated interference mitigation approach is 3.5 dB.

Analysis and compensation of frequency offset in co-site adjacent channel interference suppression

Due to the mismatch of the circuit oscillators, there will always be a frequency offset between the transmitter and the receiver. In the adjacent channel interference (ACI) suppression system using the reconstruction and cancellation method, the frequency offset decreases the accuracy of the reconstructed signal and introduces a time-varying term in the interference cancellation, resulting in poor performance of the ACI suppression. In this paper, the relationship between the normalized frequency offset, signal-to-noise ratio and the loss of interference suppression capability is analyzed through formula derivation and simulation. The validity of the frequency offset compensation method based on the pilot sequence is verified, and the relationship between the sequence length and the estimation accuracy is given. This paper provides necessary method reference and data support for the engineering of ACI suppression.

On potential challenges of V2X sidelink relaying under interference: link-level and system-level simulation with neural network assisted

The ever-increasing demand for high data rates and high connection densities in the vehicle communication network, along with the widespread adoption of radio access over the Third Generation Partnership Project (3GPP) standard, has been a major driver for the research on cellular vehicle-to-everything (C-V2X) communication. Nevertheless, Wi-Fi and other wireless communication technology work on the 5.9 GHz unlicensed band has also undergone booming proliferation over the years. C-V2X users dedicated band on the 5.9 GHz spectrum may thus suffer from both co-channel and adjacent channel interference, which cannot be negligible, especially in urban scenarios. To this end, 3GPP has standardized relay technology in New Radio (NR) V2X sidelink to extend the transmission range under interference. In this paper, through a link-level and system-level simulation study, we evaluate the sidelink performance in relaying scenarios under different interference. Motivated by the recent success of deep learning, a novel neural network is further introduced as a unified benchmark for interference mitigation evaluation. Numerical results show that there exist challenges in the real-time optimization of transmission scheme selection and power allocation in relay-assisted cases. The simulation also reveals that the interference incurred by NR on unlicensed spectrum (NR-U) signals and other sidelink signals is intractable to be suppressed, which may bring potential challenges in future works.

Application of Tuneable Notch Filters for Improved Signal Jamming Protection

Adjacent channel interference is an inevitable consequence of the increasing number of radio signals and their widespread accessibility. In addition to this interference, information can be distorted by jamming techniques used by hackers and, in some cases, security services like the military. This research concentrated on enhancing jamming protection using a tunable notch filter, considering the growing need to ensure that accurate information reception. The necessary signal was provided through a signal source, and a barrage jammer was used to introduce the jamming signal that would interfere with the original signal. The circuit also featured an adjustable notch filter designed to mitigate the impact of the jamming signal. A spectrum analyzer was used to examine the circuit’s performance. The effectiveness of the notch filter in counteracting the effects of the jammer was examined through simulations using MatLab. Based on the distortion measurement, the signal-to-noise ratio (SNR) of the filtered signal, which was 4.92 dB, which was higher than the original signal's 1.92 dB. This finding indicates that the jamming effect was substantially reduced or eliminated. Additionally, it was discovered that without a notch filter, an increase in the jammer-to-signal noise ratio significantly decreased the signal-to-noise ratio value. However, the implementation of the notch filter prevented a drastic decline in performance, demonstrating that as the jammer-to-signal noise ratio increased, the depth of the notch also increased.

Out-of-Band Digital Predistortion for Power Amplifiers With Strong Nonlinearity

Conventional full-band digital predistortion (DPD) suppresses the inband (IB) distortion to improve the error vector magnitude (EVM) performance and simultaneously suppresses the out-of-band (OOB) distortion to reduce the adjacent-channel interference. However, its performance is very limited when the nonlinearity is strong, especially in terms of suppressing the OOB distortion. This paper proposes an OOB DPD scheme for strong nonlinearity with a special focus on suppressing the OOB distortion to reduce the adjacent-channel interference. The proposed OOB DPD is featured by specifying an arbitrary OOB-distortion band for linearization and controlling the improvement level of EVM performance. Experiments demonstrate that the proposed OOB DPD can achieve superior performance in suppressing the OOB distortion when the nonlinearity is strong. We also present analyses to show that in strong nonlinearity cases with high compression, focusing on suppressing the OOB distortion at a specific band is an effective way to improve the suppression level of the target distortion. The proposed OOB DPD can further improve the transmission power under the assurance of low adjacent-channel interference. It can be applied in communications with urgent needs in high transmission power, high efficiency, and low adjacent-channel interference, such as military communications that usually adopt low-order modulations with low EVM requirements.

Design and analyses of BER performance in a tri-directional optical transmission system

The aim of the paper is to verify the stability of the tri-directional fiber transmission system. The design of transmission methods is different wavelengths modulated in the electrical signal of 10 Gbit/s and 2.5 Gbit/s based on the corresponding architectures. The goals are to measure the influence of the signal with the same and adjacent channel interference. The experimental architecture is designed in parallel. We chose the wavelength of 1552.5 nm as the receiving signal to keep the scheme working in the same conditions for comparison. In addition, we insert an additional 25 km and 50 km single-mode fiber (SMF). The result shows that power penalty can be improved within a range of 2–3 dB if a bandpass filter (BPF) is inserted before the measurement equipment. The standard in the experiment requires a wavelength spacing of 0.8 nm between each channel. The result shows that in transmission methods with different wavelengths and distances, the power penalties are 0.304 dB, 0.595 dB, and 1.173 dB, respectively. As the transmission speed decreases with different distances of 0 km, 25 km, and 50 km, the power penalties are 0.101 dB, 0.385 dB, and 0.538 dB, respectively. With the hybrid speed under different distances, the power penalties are 0.278 dB, 0.404 dB, and 0.551 dB. The tri-directional transmission can be divided into with or without an optical switch connection, while the function of the optical switch is to divide the system into the cross and parallel switching modes. According to experimental results, the power loss is in a range of 2–4 dB, and the power reimbursement is slightly increased by 0.1–0.2 dB. To compare the results with the worst condition, the power penalties for no optical switch (OSW), OSW in bar state, and OSW in cross state are 0.756 dB, 0.317 dB, and 0.329 dB, respectively.

Performance Evaluation of Co-Channel Interference on Wireless Networks

ABSTRACT Over the past few years, a large number of mobile devices are being used in real life with the advancement of wireless technology. The explosive increase in the number of wireless mobile devices makes it impossible to avoid the co-channel interference (CCI) or adjacent channel interference (ACI) phenomenon. Therefore, this interference phenomenon has been recognized as an important problem as it causes network performance degradation. In this paper, we conducted a CCI experiment in an outdoor environment where a Wi-Fi signal is not detected and in the ns-3 simulator, and compared the CCI phenomenon with the experiment results and simulation results. As we evaluated network performance between real network and simulation, we analyzed the performance impact at each network stack how packet errors propagate to upper layers in wireless ad-hoc network and propose a theoretical maximum throughput considering error rate in the data link layer and TCP layer.

Effective Channel Planning for IEEE 802.11 Networks as a Plane Tessellation Problem. Part 2. Method of Best Channel Configuration Selection and Solutions for a Low Number of Channels

The assignation a particular channel to an access point in large, distributed IEEE 802.11 networks can present a complex challenge. Although the channel can be assigned automatically by the network controller in some cases based on specified settings, it may require human attention when this is not possible. In order to select a frequency plan, it is necessary to understand the advantages of a particular channel configuration and evaluate the resulting effects of adjacent-channel interference at the design stage. A similar problem may arise during WLAN troubleshooting. In this paper, we consider distributed flat wireless networks as regular structures in plane tessellation and propose a method for finding the best channel configurations for the most efficient channel planning of IEEE 802.11 networks, which take the specifics of spectrum use in these networks into account. In addition, we consider the simplest possible solutions for three- and four- channel frequency plans.

Millimeter-Wave Multi-Channel Backscatter Communication and Ranging with an FMCW Radar.

A multi-channel backscatter communication and radar sensing system is proposed and demonstrated in this paper. Frequency modulated continuous wave (FMCW) radar ranging is integrated with simultaneous uplink data transmission from a self-packaged active radio frequency (RF) tag. A novel package solution is proposed for the RF tag. With the proposed package, the RF tag can transmit a 32-QAM signal up to 2.5 Gbps and QPSK signal up to 8 Gbps. For a multi-tag scenario, we proposed using spread spectrum code to separate the data from each tag. In this case, tags can be placed at arbitrary locations without adjacent channel interference. Proof-of-concept simulations and measurements are demonstrated. A 625 Mbps data rate is achieved in a dual-tag scenario for two tags.

Effective Channel Planning of IEEE 802.11 Networks as a Plane Tessellation Problem. Part 1. Adjacent Channel Interference Model

IEEE 802.11 wireless networks design process is impossible without a correct choice of a channel plan, i.e. a set of channels of a given type. This is especially important because channel planning of a distributed network heavily depends on the network designer’s and administrator’s decisions. Additionally, the central frequencies of the channels provided by the standard do not mean that the channels are non-overlapping. However, considering the coverage of a flat area as a plane tessellation by coverage areas of access points, for a particular regular structure geometry, it is necessary to choose the best channel planning solution among the possible ones. To do this, it is required to consider practically applicable channel planning cases, which use different numbers of channels, as a plane tessellation problem, also taking into account the overlapping of their spectral masks. This paper considers channel planning of IEEE 802.11 networks as a plane tessellation with regular structures and proposes a model that takes into account the effects of adjacent-channel interference, provides evaluation criteria, and thus is applicable to select the best channel configuration for the corresponding regular structure.

Analysis of LTE-M Adjacent Channel Interference in Rail Transit.

Long Term Evolution-Metro (LTE-M), as a special communication system for train control, has strict requirements on adjacent channel interference (ACI). According to the 3rd Generation Partnership Project (3GPP) protocol of the European Telecommunications Standards Institute (ETSI) standards, this paper presents the required isolation degree for LTE-M systems to resist ACI. Aiming at the scenario of leaky cable transmission and antenna transmission adopted by the underground LTE-M system of the subway, the isolation degree required for LTE-M system deployment is deduced by combining the channel description with the principle of ACI. For the coexistence of a LTE-M system and an adjacent cellular system in a subway ground scenario, the Monte-Carlo (MC) method is used to simulate several conceivable scenarios of the LTE-M system and the adjacent frequency cellular system. In addition, the throughput loss of the LTE-M system is estimated by considering signal to interference plus noise ratio (SINR). Simulation results demonstrate that adjacent frequency user equipment (UE) has negligible small interference with the LTE-M underground system when using the leaky cable radiation pattern, whereas for the LTE-M ground system, the main interference comes from the adjacent frequency UE to the LTE-M base station (BS). Finally, interference avoidance solutions are presented, which can be utilized as a reference in the design and deployment of LTE-M systems in the rail transit environment.

Coefficient of Restitution based Cross Layer Interference Aware Routing Protocol in Wireless Mesh Networks

In Multi-Radio Multi-Channel (MRMC) Wireless Mesh Networks (WMN), Partially Overlapped Channels (POC) has been used to increase the parallel transmission. But adjacent channel interference is very severe in MRMC environment; it decreases the network throughput very badly. In this paper, we propose a Coefficient of Restitution based cross layer interference aware routing protocol (CoRCiaR) to improve TCP performance in Wireless Mesh Networks. This approach comprises of two-steps: Initially, the interference detection algorithm is developed at MAC layer by enhancing the RTS/CTS method. Based on the channel interference, congestion is identified by Round Trip Time (RTT) measurements, and subsequently the route discovery module selects the alternative path to send the data packet. The packets are transmitted to the congestion free path seamlessly by the source. The performance of the proposed CoRCiaR protocol is measured by Coefficient of Restitution (COR) parameter. The impact of the rerouting is experienced on the network throughput performance. The simulation results show that the proposed cross layer interference aware dynamic routing enhances the TCP performance on WMN.

Method of carrier frequency arrangement for suppressing the adjacent channel interference caused by camera nonlinearity during LED-multispectral imaging

Using a camera and frequency-division modulation to obtain LED-multispectral images has the advantages of fast speed and low cost. However, when the carrier frequency is not arranged properly, the nonlinearity of the camera causes harmonic interference, which affects the signal quality of adjacent channels. This paper proposes a scheme for carrier frequency arrangement according to the high frequency, which is four times as high as the adjacent low frequency; that is fn+1=4fn,(n=1,2,3,…). The experimental result shows that the scheme can suppress the interference among carrier channels. In addition, the high-speed, phase-locked algorithm is used to demodulate the images, saving about 97.73% of the time compared to the traditional demodulation algorithm. The method not only realizes the fast acquisition of LED-multispectral images, but also improves the demodulation quality and speed of the images. It also provides a reference for a camera to obtain high-quality, LED-multispectral images.

A Ka-Band SATCOM Transceiver in 65-nm CMOS With High-Linearity TX and Dual-Channel Wide-Dynamic-Range RX for Terrestrial Terminal

In this article, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -band satellite communication (SATCOM) transceiver is first presented using a standard CMOS technology. The proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -band SATCOM transceiver consists of a high-linearity transmitter (TX) and dual-channel receiver (RX); both TX and RX are based on direct-conversion architecture. By implementing the dual-channel RX, multiple multiplexing modes, including polarization multiplexing and frequency multiplexing, can be enabled depending on the application. The RX variable gain is distributed in both RF blocks and baseband blocks to achieve a wide input dynamic range. The LNA employs a dual-coupling transformer for a low-noise figure (NF) and wideband input matching; moreover, it enhances the amplifier unilateralization characteristic to mitigate the loading effect from switched attenuators. An adjacent channel interference (ACI) cancellation scheme is proposed to further enhance the RX linearity in the frequency multiplexing mode. In the TX, single-turn high-quality-factor transformer is employed to realize matching network and four-way power combining. A prototype of the SATCOM transceiver is fabricated in a standard 65-nm CMOS process. Under 1.05-V supply voltage, the TX achieves a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {SAT}}$ </tex-math></inline-formula> of 20.5 dBm and an average output power of 12 dBm with 2% error vector magnitude (EVM) and a 37.6-dB ACPR. The dual-channel RX achieves an NF of 5.4 dB, an IIP3 of −30 dBm on the high-gain mode, the ACI cancellation is measured of 7.9 dB with a 100-MHz signal bandwidth.

Spectral Emission Mask Shaping for OFDM in Cognitive Radios

Orthogonal frequency division multiplexing (OFDM) is characterized by spectral efficiency. It enables flexible and agile spectrum allocation. But still it lags as it suffers from spectral leakage in the form of large side lobes. It leads to inter-channel interference if not handled carefully.in proposed system spectral emission mask system is implemented to combat spectral leakage and ultimately avoiding adjacent channel interference. A spectral mask, also known as a channel mask or transmission mask is a mathematically-defined set of lines applied to the levels of radio (or optical) transmissions. The spectral mask is generally intended to reduce adjacent-channel interference by limiting excessive radiation at frequencies beyond the necessary bandwidth. The proposed system is implemented over MATLAB platform using script language.