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Frequency-modulated continuous-wave (FMCW) radars are becoming increasingly important in industrial applications due to their low cost, simple signal processing, and high resolution. The research is driven by the growing trend of radar applications in industrial settings, including tasks like autonomous robot navigation, radar-based monitoring of humans, and enhancing safety across various scenarios, such as smart factories, traffic control, or environmental monitoring. The network of distributed sensor nodes is a feature to be implemented by the sixth generation of wireless mobile networks. As a result, 6G will become an enabler technology that will develop even further use cases and advance the expansion of these technologies. Therefore, the mutual interference of these sensor systems is becoming highly relevant since they can be avoided by scheduling the individual resources of the sensor nodes by a network structure. This paper investigates the interference behavior of FMCW radar sensors in a dense indoor scenario. In these environments, in particular, the reliability of the sensor system plays an important role, and disruption can have critical consequences like not recognizing a target, triggering a false alarm, or the complete failure of the sensing. To correctly classify the expected interference in the overall context, the paper investigates the physical layer effects on the performance, such as multipath propagation, channel spread, delay, Doppler shift, and attenuation. By evaluating these effects using state-of-the-art signal processing, it was revealed that a high channel spread in particular and the dynamics of the radar channel can significantly reduce the detection quality, as the interference power can exceed the received power by up to 20 dB, depending on the scenario. The simulation results given in this paper show that a potential communication between the radars and compliance with a synchronization delay, the interference problems can be reliably prevented with an appropriately designed anti-aliasing filter. Our simulations have quantified the detection performance under interference through the entire signal chain by evaluating the physical layer, the radar signal processing with non-idealities, and the hardware. The paper has investigated interference probability in indoor environments by examining radars with uncoordinated transmissions. Integrating findings from the physical propagation characteristics, the deviations in chirp durations, and the frequency of interference cases offers insights into the potential risk of interference.

Quantum computing, a transformative field that emerged from quantum mechanics and computer science, has gained immense attention for its potential to revolutionize computation. This paper aims to address the fundamentals of quantum computing and provide a comprehensive guide for both novices and experts in the field of quantum computing. Beginning with the foundational principles of quantum computing, we introduce readers to the fundamental concepts of qubits, superposition, entanglement, interference, and noise. We explore quantum hardware, quantum gates, and basic quantum circuits. This study offers insight into the current phase of quantum computing, including the noisy intermediate-scale quantum (NISQ) era and its potential for solving real-world problems. Furthermore, we discuss the development of quantum algorithms and their applications, with a focus on famous algorithms like Shor’s algorithm and Grover’s algorithm. We also touch upon quantum computing’s impact on various industries, such as cryptography, optimization, machine learning, and material science. By the end of this paper, readers will have a solid understanding of quantum computing’s principles, applications, and the steps involved in developing quantum circuits. Our goal is to provide a valuable resource for those eager to embark on their quantum computing journey and for researchers looking to stay updated on this rapidly evolving field.

The emergence of connected automated vehicles and advanced V2X applications and services can challenge the scalability of vehicular networks in the future. This challenge requires solutions to reduce and control the communication channel load beyond the traditional congestion control protocols proposed to date. In this paper, we propose and evaluate the use of V2X message compression to reduce the channel load and improve the scalability and reliability of future vehicular networks. Data compression has the potential to reduce the channel load consumed by each vehicle without reducing the amount of information transmitted. To analyze its potential, this paper evaluates the compression gain of three compression algorithms using standardized V2X messages for basic awareness (CAMs), cooperative perception (CPMs) and maneuver coordination (MCMs) extracted from standard-compliant prototypes. We demonstrate through network simulations that V2X message compression can reduce the channel load. In particular, the tested compression algorithms can reduce the channel load by up to 27% without reducing the amount of information transmitted. Reducing the channel load and the consequent interferences significantly improves the reliability of V2X communications. However, this study also emphasizes the need for high-speed compression and decompression modules capable to compress and decompress V2X messages in real time, especially under highly loaded scenarios.

The orthogonal time-frequency space (OTFS) modulation is resistant to double selective fading, making it a promising modulation scheme for next-generation integrated sensing and communication (ISAC) systems. Nonetheless, there exists a problem of mutual interference between uplink communication signals and sensing echo signals, which leads to the degradation of both information transmission and sensing performance. For this reason, this paper investigates a successive interference cancellation (SIC) method based on the delay-Doppler (DD) domain to suppress the interference between the sensing signals and communication signals, thereby ensuring the accuracy of communication signal detection and sensing parameter estimation. After receiving the mixed signals at the receiver, these signals are transformed from the time-frequency (TF) domain to the DD domain. Firstly, the sensing echo signal is treated as interference to the communication signal, which is detected using a threshold-based channel estimation method and the Message Passing (MP) algorithm. The communication signal is then reconstructed and subtracted from the mixed signal. At last, the remaining signal is then subjected to parameter estimation with the Maximum Likelihood (ML) algorithm. Simulation results demonstrate that this method allows the ISAC system to operate effectively in both communication and sensing tasks. Compared to the scenario without considering signal interference, the sensing parameter estimation is improved by approximately 6 dB. Additionally, compared to traditional interference suppression methods belonging to TF domain, the performance of sensing parameter estimation is improved by approximately 2 dB.

Inbound handover (HO) or hand-in is done when the user equipment (UE) performs HO from a macrocell (MC) to a small cell (SC), while the outbound HO or handout is done when a UE hands over from SC to MC. On the other hand, the inter-SC HO is done when a UE performs HO between two SCs. The outbound HO is not as complex as the other two types, because the UE has only one HO target base station, i.e., the MC. Therefore, in this paper, we only consider the inbound and inter-SC HO types. The user may associate with a small cell for a very short time of stay (ToS), smaller than a short time of stay threshold, and this may cause frequently unnecessary HOs and result in service interruption causing degradation in the quality of service (QoS). In this paper, we propose a novel HO method for the purpose of load balancing and throughput improvement in heterogeneous networks (HetNets). The influence of interference from both MC and SC base stations is taken into account so as to offloaded the user from the congested cell and forced it to HO to the SC that gives a good data rate by choosing the best SC, which has the highest signal to interference plus noise ratio (SINR), from a reduced neighbor cell list (NCL). The NCL is optimized utilizing the SINR threshold and ToS. The proposed method utilizes a modified A3 HO initiation event taking into account the cell load and the interference. Results show that the proposed method can perform HO while maintaining the throughput to a good level. In addition, the proposed method has significantly reduced the inter-SC HOs and inbound HO and radio link failures compared to the existing methods. Under different network conditions, load factors, and call arrival rates, results show that the proposed method can give significantly better performance, thereby producing higher throughput for the user and the network.

The universal filtered multi-carrier (UFMC) has been taken as a promising candidate for future wireless communication, where a finite impulse response filter is employed to shape the waveform and enhance its resistance to inter-carrier interference. In previous studies, the Dolph-Chebyshev filter had been used due to its low-sidelobe levels, but at the cost of low flexibility to filter the performance control. Hence, this paper puts forward an effective scheme to design an anti-interference filter for UFMC system, where the Nyquist condition (or sampling inter-symbol interference equivalently), the in-band distortion, and the out-of-band emission are taken into consideration. First, this paper models the filter design as a constrained minimax optimization concerning above-mentioned filter performance indexes. Then, the original nonconvex constraints on Nyquist condition are approximately transformed to a linear matrix inequation and two linear inequations. Finally, the optimization problem is solved by semidefinite programming. The numerical examples explicitly demonstrate the flexible performance tradeoff of the proposed method, in which the included filter performance indexes can be effectively controlled. Moreover, the bit-error-rate (BER) tests of the UFMC system confirms the effectiveness of our study, where the designed filters show BER advantages over filters of the previous literature. Therefore, the proposed waveform shaping filters can benefit variant applications of UFMC for its flexible performance tradeoffs as well as the improved anti-interference performance.

Ultra-dense small cell deployment in future 5G networks is a promising solution to the ever increasing demand of capacity and coverage. However, this deployment can lead to severe interference and high number of handovers, which in turn cause increased signaling overhead. In order to ensure service continuity for mobile users, minimize the number of unnecessary handovers and reduce the signaling overhead in heterogeneous networks, it is important to model adequately the handover decision problem. In this paper, we model the handover decision based on the multiple attribute decision making method, namely Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The base stations are considered as alternatives, and the handover metrics are considered as attributes to selecting the proper base station for handover. In this paper, we propose two modified TOPSIS methods for the purpose of handover management in the heterogeneous network. The first method incorporates the entropy weighting technique for handover metrics weighting. The second proposed method uses a standard deviation weighting technique to score the importance of each handover metric. Simulation results reveal that the proposed methods outperformed the existing methods by reducing the number of frequent handovers and radio link failures, in addition to enhancing the achieved mean user throughput.

To improve the data rate in a camera-based visible light communication system, multiple LEDs in an LED array are used to transmit multiple bits in one frame. The problem is that LEDs are always captured in the image with some degree of blooming effect. This effect increases the intensity of pixels surrounding the origin LEDs in the image. When multiple LEDs are used, the blooming effect from all LEDs causes the interpixel interference (IPI) problem that greatly degrades the quality of the received signal. This paper analyzes the blooming effect and finds that the IPI problem increases when the number of ``ON”LEDs in the array increases. Through the analysis, this paper proposes a differential coding to minimize the number of ``ON”LEDs in every transmitted frame and thus minimize the IPI effect. The proposed scheme is then verified through simulations. The results show that a lower bit error rate, which indicates a better signal quality, can be achieved by applying the proposed scheme.

The envisioned dense nano-network inside the human body at terahertz (THz) frequency suffers a communication performance degradation among nano-devices. The reason for this performance limitation is not only the path loss and molecular absorption noise, but also the presence of multi-user interference and the interference caused by utilising any communication scheme, such as time spread ON-OFF keying (TS-OOK). In this paper, an interference model utilising TS-OOK as a communication scheme of the THz communication channel inside the human body has been developed and the probability distribution of signal-to-interference-plus-noise ratio (SINR) for THz communication within different human tissues, such as blood, skin, and fat, has been analyzed and presented. In addition, this paper evaluates the performance degradation by investigating the mean values of SINR under different node densities in the area and the probabilities of transmitting pulses. It results in the conclusion that the interference restrains the achievable communication distance to approximate 1 mm, and more specific range depends on the particular transmission circumstance. Results presented in this paper also show that by controlling the pulse transmission probability and node density, the system performance can be ameliorated. In particular, SINR of in vivo THz communication between the deterministic targeted transmitter and the receiver with random interfering nodes in the medium improves about 10 dB, when the node density decreases one order. The SINR increases approximate 5 and 2 dB, when the pulse transmitting probability drops from 0.5 to 0.1 and 0.9 to 0.5.

In 2015, the international telecommunication union (ITU) proposed 11 candidate millimeterwave bands between 24 and 86 GHz for the deployment of future fifth mobile generation (5G) broadband systems. Furthermore, the ITU called for spectrum-sharing studies in these bands. Since 5G specifications are not yet defined, the utilization of radio spectrum by 5G mobile systems will assist in identifying these specifications. This paper introduces Malaysia as a case study for the deployment of 5G systems. This includes a discussion of the current status of the Malaysian telecommunication market. Then, we investigate the current services that are already deployed in the proposed bands. Our investigation shows that the fixed (F) service is the most deployed as a primary service in the candidate bands. For this reason, a preliminary spectrum-sharing study is conducted on the basis of a modified 5G spectrum-sharing model to evaluate the feasibility of coexistence between 5G and F services in the 28-GHz band. Our modified methodology can be used for spectrum-sharing studies between 5G and any other services for an initial spectrum-sharing investigation. The results show that the F service will be severely affected by the 5G system transition in the 28-GHz band, especially in the base station (BS)-to-BS sharing scenario. The best band from the perspective of current spectrum allocation for 5G systems is the 45-GHz (i.e., 45.5-47 GHz) band, since it is already reserved for mobile service for primary allocation and not utilized. This paper is carried out concurrently with current worldwide efforts investigating spectrum sharing, as requested by the ITU in agenda item 1.13 for the next world radio conference 2019.

Non-orthogonal multiple access (NOMA) is promoted as a key component of 5G cellular networks. As the name implies, NOMA operation introduces intracell interference (i.e., interference arising within the cell) to the cellular operation. The intracell interference is managed by careful NOMA design (e.g., user clustering and resource allocation) along with successive interference cancellation. However, most of the proposed NOMA designs are agnostic to intercell interference (i.e., interference from outside the cell), which is a major performance limiting parameter in 5G networks. This paper sheds light on the drastic negativeimpact of intercell interference on the NOMA performance and advocates interference-aware NOMA design that jointly accounts for both intracell and intercell interference. To this end, a case study for fair NOMA operation is presented and intercell interference mitigation techniques for NOMA networks are discussed. This paper also investigates the potential of integrating NOMA with two important 5G transmission schemes, namely, full duplex and device-to-device communication. This is important since the ambitious performance defined by the third generation partnership project for 5G is foreseen to be realized via seamless integration of several new technologies and transmission techniques.

Recorded Electroencephalogram (EEG) signals are typically affected by interference and artifacts, which can both impact eye reading and computer analysis of the data. Artifacts are induced by physiological (noncerebral) activities of the patient, such as muscular activities of the eyes, or the heart, or the body, while interference may be of external or internal origin. External interference can be induced by electrical machines if the latter are in the same room as the patients, while internal interference can be caused by abnormal breathing, or body movement, or electrode malfunction, or headset movements. Interference may cause severe distortion of EEG signals, resulting in loss of some segments of brain signals, while artifacts are additive signals to brain signals. Therefore, in order to analyze the brain activity signals of a patient, we need to identify and eliminate interference and isolate artifacts. In this paper, we analyze the EEG signals that were recorded using a headset with fourteen channels placed on the heads of comatose patients at the National Institute of Neurology in Tunis, Tunisia. We identify the interference using a robust statistical method known as projection statistics and we separate the brain signals from the artifacts cited above by applying an independent component analysis method. Finally, we show the multifractal behavior of the EEG signals without interference by applying the wavelet leader method and analyze their properties using the singularity spectrum.

To achieve high density, the spacer length of three dimensional (3D) NAND device has been scaled down. When the program/erase cycle repeats, problems such as electrons accumulation in the inter-cell region are occurred. To solve this problem, a method of replacing the spacer region material of 3D NAND device with a low-k materials has been proposed. In 3D NAND, carrier’s lateral spreading occurs since all cells in the string share a same trap layer. In this work, we observed the change of cell current (Icell) and interference characteristic after retention time on various dielectric constant of spacer region conditions. These two factors exhibit a trade-off characteristic. In this paper, we suggested the appropriate range of dielectric constant value. Based on this observation, we have proposed a suitable range of dielectric constants and suggested the Si3N4/ Air / Si3N4(N/A/N) multiple dielectric spacer structure to improve both Icell and interference characteristics. In addition, performance improvement can be obtained through high-k / low-k / high-k multiple dielectric spacer structure. Improving the retention characteristics of 3D NAND flash memories through the proposed structure will contribute to improving the reliability of memory devices.

Long-Range networks are increasingly used in smart spaces due to their ability to provide longer communication range while consuming low energy. To facilitate communication among different Long-Range nodes, a gateway is used. For instance, in smart buildings such as airports, railway stations, indoor stadiums, and auditoriums, sensory data from multiple sites are transferred to a base station through a Long-Range gateway. However, when multiple nodes transmit data simultaneously to the gateway, it generates network interference, especially in high-ceiling smart buildings where Long-Range nodes with sensors are attached to monitor the building’s health. In this paper, we present a new method for identifying interfering Long-Range Nodes (LNs) in high-ceiling smart buildings using a classification model. Our approach involves gathering and analyzing network parameters, such as signal-to-noise ratio and received signal strength indicator, from the signals to extract features that the classifier uses for interference classification. The approach categorizes interference based on the number of interfering LNs, with each class representing a distinct number of interfering LNs. We also introduce a push-based mechanism to detect and adjust the power levels of faulty LNs, reducing interference. Our method is cost-effective as it is hardware-independent, making it feasible to implement on the LG platform. Finally, we present a dataset of network interference generated by varying the number of nodes, obstacles, and other parameters. We train the model on the generated dataset and evaluate its effectiveness using a test bed. The experimental results demonstrate that the approach can successfully identify interference nodes in a complex network.

The demand for wireless connectivity has increased recently, driven primarily by Internet of Things (IoTs) and 6G applications. Since various wireless networks operate on an unlicensed band and coexist with upcoming IoT networks, undesired interference in IoT networks from other networks is inevitable. In addition, interference heavily affects the lifetime of IoT networks owing to their limited battery capacity. However, the interference of underlay networks in hierarchical coexisting networks has not yet been analyzed and its impact on energy efficiency remains uncharacterized. In this paper, the energy efficiency of the underlay network is statistically analyzed in the presence of interference from a coexisting overlay network. Based on our analyses, a closed-form expression for the average energy efficiency of the underlay network is derived and a packet size that maximizes the average energy efficiency is then proposed. The results of our analyses are consistent with the actual results, confirming that both the average energy efficiency of the underlay network and its optimal packet size can be readily obtained using our analyses without the need for extensive simulations. Simulation results confirmed the validity of the our statistical analyses. The simulation results demonstrate that our analyses can accurately and analytically determine the energy efficiency of the underlay network, and the proposed packet size can achieve more than 99 % of the optimal performance. The feasibility of adaptive packet tuning is also verified using actual overlay packet traces as inputs for our simulation.

Time Reversal (TR) has been proposed as a competitive precoding strategy for low-complexity devices, relying on ultra-wideband waveforms. This transmit processing paradigm can address the need for low power and low complexity receivers, which is particularly important for the Internet of Things, since it shifts most of the communications signal processing complexity to the transmitter side. Due to its spatio-temporal focusing property, TR has also been used to design multiple access schemes for multi-user communications scenarios. However, in wideband time-division multiple access schemes, the signals received by users suffer from significant levels of inter-symbol interference as well as interference from uncoordinated users, which often require additional processing at the receiver side. This paper proposes an iterative TR scheme that aims to reduce the level of interference in wideband multi-user settings, while keeping the processing complexity only at the transmitter side. The performance of the proposed TR-based protocol is evaluated using analytical derivations. In addition, its superiority over the conventional Time Reversal Division Multiple Access (TRDMA) scheme is demonstrated through simulations as well as experimental measurements at 2.5 GHz carrier frequency with variable bandwidth values.

Massive MIMO is dominant in the current wireless communication systems. Massive MIMO system uses a massive number of antennas to serve multi-users simultaneously. The growth of served users in the system will increase the interference between them and affect the system’s performance. To maintain the qualified service for the growing number of users, user selection techniques can be used to separate users into groups to be served well. This paper proposes three user selection methods named Mean Step User Selection (MSUS), Second Null User Selection (SNUS), and Interference Threshold User Selection (ITUS) methods. These three user selection methods aim to serve users with the best possible performance. The performance of these proposed user selection methods will be evaluated and compared with the performance of the system without selection and with the system using other user selection methods such as Random User Selection (RUS), Semi-orthogonal User Selection (SUS), and Inter-Channel Interference Based Selection (ICIBS) methods. The simulation shows that the proposed MSUS, SNUS, and ITUS methods provide an improvement in the spectral efficiency of 75.39%, 92.13%, and 153.71% when compared with the system without the selection method. The proposed user selection methods also improve performance compared to other user selection methods.

Although LoRa (radio) technology offers customization of different physical layer transmission parameters such as bandwidth, spreading factor (SF), transmission power, and coding rate to obtain the desired data rate and coverage, the currently preferred single-hop transmission mode cannot simultaneously achieve both. The LoRaWAN community is therefore focusing on multi-hop networks to increase network longevity while extending coverage. In this paper, a detailed mathematical model for a multi-hop network that modifies the Distance Ring Exponential Stations Generator (DRESG) framework is presented. The relay operation is carried out through intermediate gateways, and a distance-based adaptive transmission configuration approach is used. On the basis of the performance metrics, i.e., packet delivery ratio (PDR) and energy usage of end nodes, we compare and contrast the performance characteristics of several routing schemes, including single-hop (SH), next-ring-hop (NRH), and variable-hop (VH) routing. The research covers some core issues, including interference, environmental conditions, and transceiver power constraints, and sets the stage for evaluating various multi-hop LoRa solutions as well as optimizing several implementation factors.

With new services emerging in fifth generation (5G)-advanced, the evolution in duplex modes plays an important role to meet more stringent requirements for both downlink (DL) and uplink (UL) transmissions. In this paper, sub-band full duplex (SBFD) at base station (BS) is studied as an attainable evolution of the traditional time division duplex (TDD). Both user equipment (UE) transparent SBFD and UE perceptive SBFD are proposed and studied to serve different types of UEs. To tackle the interference introduced by SBFD, a model including both BS self-interference and cross-link interference (CLI) is presented as a first step, and new interference management schemes are proposed. Three approaches to mitigate BS self-interference, namely the passive suppression, analog interference cancellation and digital interference cancellation are analyzed. A new framework for CLI management is illustrated along with enhancements for interference identification, spatial domain interference coordination and power domain adjustment. To validate the feasibility and performance of the proposed SBFD methods under indoor and dense urban scenarios, system-level simulations (SLSs) are carried out and a proof-of-concept (PoC) is developed for the purpose of obtaining experimental results.

Low-Earth orbiting (LEO) satellites now hold promise to provide broadband service anywhere in the world, but they must share the radio spectrum with geosynchronous Earth-orbiting (GEO) satellites. The United Nations International Telecommunications Union (ITU) and the U.S. Federal Communications Commission (FCC) require that operators of LEO satellite systems avoid interfering with GEO satellite systems even though both use the same bands within the radio spectrum. Such interference can occur when a LEO satellite passes through an area between a GEO earth station and its intended GEO satellite. This is called an in-line event. In this paper we develop a first order estimate of the probability of occurrence of such an event, an indication that Ku-band LEO-to-GEO interference is a serious problem. We describe the use of beam steering to mitigate such interference and consider its feasibility for currently deployed LEO constellations. We find that beam steering appears to be a practical and effective approach for a LEO constellation that has this capability and uses sufficiently narrow beams.

In the last couple of decades, multicarrier modulations have witnessed a considerable interest in wireless communication networks due to their ability to fight against multipath fading and offer multiple access with flexible resource sharing. One of the well known multicarrier modulation systems is filter-bank multi-carrier with an offset quadrature amplitude modulation (FBMC/OQAM), which was proposed as a powerful solution during the standardization of 5G. In this paper, we derive a closed-form expression of the signal to interference plus noise ratio (SINR) for FBMC/OQAM systems in the discrete-time context, for arbitrary wide sense stationary uncorrelated scattering (WSSUS) channels as well as transmitter (Tx) and receiver (Rx) waveforms. We quantify the potential gains in SINR brought by FBMC/OQAM, which exclusively operates on critical lattice density, with respect to FBMC/QAM, which have the flexibility to operate on critical or non-critical lattice densities. For completeness, we compare the performance of FBMC/OQAM in the discrete-time context, sweeping the discrete space of waveforms supports, with that of FBMC/OQAM in the continuous-time context, using the Hermite functions, and show how they perform similarly. Simulation results prove that FBMC/OQAM optimization algorithm, performing with the ping-pong optimized pulse shaping (POPS) paradigm, converges rapidly to excellent SINR values, even with small supports durations, in discrete-time context, which is equivalent to a reduced number of Hermite functions, in the continuous-time context.

IoT networks are more and more present nowadays. Some IoT protocols share the same bandwidth leading to interference on neighboring networks and decrease of overall coverage. To contribute to this problem, an analytical study of the coverage of a LoRa network with underlying uncoordinated IoT networks for uplink transmissions is presented in this paper. Using stochastic geometry, closed form analytical expressions are proposed allowing to analyze the success and coverage probabilities for a LoRa network. An appropriate model of the path loss including real-life values is used to characterize the log-distance propagation parameters. The interference comes from both the LoRa network itself and the underlying IoT networks, modeled with an $\alpha $ -stable distribution based on recent measurements. It is shown that for an environment with a huge amount of surrounding uncoordinated IoT networks, the gateways deployment should be doubled to reach a decent coverage probability, compared to an environment where the underlying interfering networks are not considered.

The number of fifth generation (5G) base stations (BSs) installed for commercial services continues to increase in South Korea since the first 5G rollout of the 3.5 GHz band in 2019. However, this will cause a rapid increase in the cost and effort required for an electromagnetic field (EMF) installation compliance measurements of a 5G BS. This paper studies an appropriate measurement spacing for EMF installation compliance assessments of a 3.5 GHz 5G BS. Ray-tracing simulations based on the ray frustum technique are performed for three installation scenarios according to the accessibility categories provided in the International Telecommunication Union-T K.52 recommendation to observe the power density exposure trends. An interference analysis using the two-ray propagation model indicates that the spacing of 1 m can be suitable for the installation compliance of a 5G BS above 3 GHz. In addition, it was found that this spacing could be also applied up to the higher frequency of 7.125 GHz, the upper limit of Frequency Range 1 defined in the 3rd Generation Partnership Project specification. Measurements based on two different 5G signal extrapolations using the Synchronization Signal Block were conducted to validate the spacing of 1 m for a 3.5 GHz 5G BS established by simulation studies.

Traditional wired interconnects in multicore multichip (MCMC) systems can be replaced with chip-integrated switched beam antenna arrays to provide reconfigurable chip-to-chip communications. By simply switching the directive beams of the arrays, the chips can be made to dynamically communicate with their surrounding neighbors. Radiation from the arrays in the unintended direction, however, causes interference when multiple pairs of chips are simultaneously communicating. In this paper, the noise and interference limitations of such concurrent chip-to-chip communication systems are analyzed at 60 GHz for the channels defined in the IEEE 802.11ay standard. Each array consists of eight substrate integrated waveguide (SIW) horn elements printed on a thin dielectric substrate. The elements can be individually excited to produce eight directive endfire beams, providing full 360° coverage, in the horizontal plane. The substrate acts as a hybrid space-surface wave interconnect (HSSW-I) that allows near-field, space and surface wave coupling to occur between the arrays, and thus, increases interchip transmission. The antenna and link parameters that dictate the signal-to-noise-plus-interference ratio (SNIR) of such systems are established by considering all the major components. The maximum achievable data rates are then determined based on the SNIR, calculated from the measured and simulated transmission coefficients between the arrays.

Flying base stations (FlyBSs) enable ubiquitous communications in the next generation mobile networks with a flexible topology. However, a deployment of the FlyBSs intensifies interference, which can result in a degradation in the throughput of cell-edge users. In this paper, we introduce a flexible soft frequency reuse (F-SFR) that enables a self-organization of a common SFR in the networks with an unpredictable and dynamic topology with the FlyBSs. We propose a graph theory-based algorithm for an allocation of resource plans, which is understood as a bandwidth allocation and a transmission power setting in the context of SFR. Furthermore, we introduce a low-complexity implementation of the proposed resource allocation using deep neural network (DNN) to significantly reduce the computation complexity. We show that the proposed F-SFR increases the throughput of cell-edge users by 16% to 26% and, at the same time, improves the satisfaction of the cell-edge users by up to 25% compared to the state-of-the-art solutions. We also demonstrate that the proposed scheme ensures a higher fairness in the throughput among the users with respect to the state-of-the-art solutions. The implementation via DNN also outperforms all state-of-the-art solutions despite its very low complexity.

In this paper we propose LoRaSyNc (LoRa receiver with SyNchronization and Cancellation), a second generation LoRa receiver that implements Successive Interference Cancellation (SIC) and time synchronization to improve the performance of LoRa gateways. Indeed, the chirp spread spectrum modulation employed in LoRa experiences very high capture probability, and cancelling the strongest signal in case of collisions can significantly improve the cell capacity. An important feature of LoRaSyNc is the ability to track the frequency and clock drifts between the transmitter and receiver, during the whole demodulation of the interfered frame. Due to the use of low-cost oscillators on end-devices, a signal cancellation scheme cannot result accurate without such a tracking, especially at the lower data rates. We validate the performance of LoRaSyNc in presence of collisions by implementing a receiver prototype on software-defined-radios, and perform several experiments in different realistic scenarios, by also comparing our receiver with commercial gateways. Finally, we simulate a cell deployment with one or more gateways, showing that the proposed scheme improves performance by almost 50% compared to a traditional receiver.

This paper introduces the dual-entropy method for oscillator-based digital random number generators (RNG). The standard model for elaborating jitter-based RNG is expanded to account for the sampling time uncertainty. It is explained that combining the jitter of the sampling clock with the uncertainty of the sampled signal proves to be the most efficient method for harvesting entropy from jitter. Dual-entropy configuration also improves the robustness of the RNG against correlation, interference, and injection-based attacks in hardware. Numerical analysis and experimental results show that the negative effect of external interference on the entropy of the output bitstream is significantly reduced in dual-entropy-based RNG. The proposed method is demonstrated on a ring-oscillator-based design and implemented on FPGA. It is tested using NIST 800-22, Dieharder, and TestU01 batteries and observed to produce successful random bitstreams at a maximum center frequency of 45 MHz on Zedboard Zynq and 114 MHz on ZCU102 Zynq Ultrascale+ evaluation kits without post-processing.

This paper presents a method based on the global navigation satellite system (GNSS) interference signals to facilitate wide area protection against numerous unintentional drones. The defensive GNSS signals generated by a single signal generator sweep the authentic GNSS signals, and that the signal tracking loop tracks these defensive signals so that the drones can be guided to a safe zone. The proposed algorithm performs a sweep in the measurement domain by adjusting the time offset of the signal generator, which makes it possible to sweep a wider area. To confirm the possibility of wide area protection, we investigated the signal generation method for the transition of signal tracking locks from authentic to defensive signals in situations where a signal generator cannot identify the drones’ positions. We examined the time discrepancy between the authentic and defensive signals and performed the worst-case analysis to determine the minimum sweep range of the time offset. The determined minimum sweep range overcomes the influence of time discrepancy and unconditionally deceives multiple drones regardless of the satellite’s position, drones’ trajectories, and entry timing. To deceive drones approaching a sphere with a radius of 1 km, the minimum sweep range equals approximately 6 and 3 km when the signal generator is 0 and 2-km away from the center of the sweep region, respectively. The simulation results verified the theoretical analysis and showed that the defensive signals transmitted by one signal generator can deceive multiple drones to the center of the sweep region, which is the intended location.

In this paper, a novel modulation and multiplexing technology for reducing out-of-band leakage is proposed for multicarrier schemes based on CP-OFDM. The proposed method is to spread data of N layers with N selected spreading codes, then multiplex them into a data sequence and transmit it on 2K subcarriers. The N spreading codes, which can suppress out-of-band leakage, are selected out from a complete set of mutual orthogonal spreading codes. The simulation results show that the data modulation and multiplexing technology effectively reduces interference with neighboring frequency bands or adjacent sub-bands for different numerologies and so significantly improves spectrum efficiency

In dense Wireless Local Area Networks (WLANs), high-density Access Points (APs) bring severe interference that seriously affects the experience of users, resulting in lower throughput and poor connection quality. Due to the heavy computation workload raised by the sizable networking systems and the difficulty in estimating instantaneous Channel State Information (CSI), existing works are hard to solve interference problem. In this paper, we propose a Joint Power control and Channel allocation based on Reinforcement Learning (JPCRL) algorithm combining with statistical CSI to reduce interference adaptively. Firstly, we analyze the correlation between transmit power and channel, and formulate the interference optimization as a Mixed Integer Nonlinear Programming (MINLP) problem. Secondly, we use the statistical CSI method to take the power and channel state as the state and action space, the overall throughput increment as the reward function of Q-learning, and obtain the optimal joint optimization strategy through off-line training. Moreover, for the periodic reinforcement learning process leading to resource consumption, we design an event-driven mechanism of Q-learning, which triggers online learning to refresh the optimal policy by event-driven condition and the consumption of computing resources can be reduced. The evaluation results show that the proposed algorithm can effectively improve the throughput compared with the existing scheme.

We present a novel ultra-wideband low-cost transmit/receive architecture with reduced power and hardware requirements, which includes interference mitigation capabilities and accommodates multiple users. Specifically, a novel encoding approach is introduced to multiplex signals across large bandwidths and achieve secure communication and interference mitigation through spread signals. In this paper, a detailed description of the proposed high data rate system architecture is presented. Simulations are also provided in the presence of high-power interferers with eight concurrent users. To assess the performance and impact of the encoding/decoding process, a noise analysis was conducted for the transmitter and receiver chains. Specifically, bit error rate curves are generated at different stages of the system. The measurements show interference margin ratios improvement by at least 16 dB.

This paper presents an Interference and Priority aware Coexistence (IPC) algorithm to ensure coexistence between multiple WBANs communicating within each other transmission range. By intelligently keeping an interfering WBAN silent, the IPC approach aims to maximize simultaneous (interference-free) transmissions from sensor nodes of different WBANs. Coordinators use beacons to exchange interference and priority aware metrics. This information is later used to generate an interference graph of the sensors associated with the coordinator and perform link scheduling. The IPC approach has been evaluated for two different interference scenarios namely, a High interference scenario which considers interference from the highest interfering coordinator or sensor node of all coexisting WBANs, and a Moderate interference scenario (conventionally used in the existing literature) which considers interference from the coordinator only. Considering the mobility of WBANs, the performance of IPC is evaluated in terms of spatial reuse, system throughput, delay, and packet delivery rate. IPC shows significant improvement in all performance metrics over existing schemes.

The flight path of the unmanned aerial vehicle (UAV) relay can significantly affect the performance of the wireless relay communication system. In this paper, we investigate the optimization of the UAV flight path in a wireless relay communication system, when a jamming or interference signal is present. The UAV flight path is optimized to maximize the signal-to-interference-plus-noise ratio (SINR), and the required parameters are estimated. The simulation results show that the proposed method can achieve performance close to an ideal SINR optimization and also highlight the benefits of optimizing the SINR instead of the signal-to-noise ratio (SNR) when a jamming or interference signal is present.

The federal communications commission (FCC) took the unprecedented step to approve the usage of TV white spaces, i.e., locally vacant TV channels, in 2012. This TV spectrum will present new opportunities for wireless access technologies and applications, e.g. femtocell networks. The utilization of TV white spaces in femtocell networks also comes with some technical challenges. One of the most fundamental is that how much capacity and energy efficiency can be achieved in TV white spaces network. Prior works only focused on capacity consideration for cellular network in outdoor scenario leaving important femtocell network in indoor scenario largely open for investigation. In this paper, we explore the capacity and energy efficiency for femtocell network by developing a TV white spaces reuse and power allocation scheme. The problem is formulated into an optimization problem with the objective to maximize the energy efficiency achieved by a femtocell network, while keeping the interference to the primary receiver and macro receiver at an acceptable level. We demonstrate the existence of a unique globally optimal transmit power vector for all the femtocells, and propose a gradient absent algorithm to obtain it. Simulation results show that the femtocell can have a considerable capacity and energy efficiency improvement by using the TV channels.

In vehicular networks, the interference is brought about by the rapid growth of various services due to the scarcity of radio resources, which poses great challenges for the network connectivity. Unlike the connectivity that is solely determined by the signal strength or the distance between pairwise vehicles, the connectivity considered in this paper is influenced by the interference among multiple links. To improve the network connectivity by interference mitigation, a connectivity optimization problem based on resource allocation is modeled using graph theory. First, the definitions of the connectivity metrics affected by interference in the vehicular networks are given. Second, the number of resources that guarantee the network connectivity is analyzed. Finally, a resource allocation algorithm based on the minimum spanning tree is proposed to improve the network connectivity that is constrained by limited resources. The simulation results confirm that the proposed algorithm approximates the optimal performance and improves the connectivity better than similar algorithms.

The computation task offloading and resource management in mobile edge computing (MEC) become attractive in recent years. Many algorithms have been proposed to improve the performance of the MEC system. However, the research on power control in MEC systems is just starting. The power control in the single-user and an interference-free multi-user MEC systems has been investigated; but in the interference-aware multi-user MEC systems, this issue has not been learned in detail. Therefore, a game theory-based power control approach for the interference-aware multi-user MEC system is proposed in this paper. In this algorithm, both the interference and the multi-user scenario are considered. Moreover, the existence and uniqueness of the Nash Equilibrium (NE) of this game are proved, and the performance of this algorithm is evaluated via theoretical analysis and numerical simulation. The convergence, the computation complexity and the price of anarchy in terms of the system-wide computation overhead are investigated in detail. The performance of this algorithm has been compared with the traditional localized optimal algorithm by simulation. The simulation results demonstrate that the proposed algorithm has more advantages than the traditional one.

The multipath transmission is one of the suitable transmission methods for high data rate oriented communication such as video streaming. Each video packets are split into smaller frames for parallel transmission via different paths. One path may interfere with another path due to these parallel transmissions. The multipath oriented interference is due to the route coupling which is one of the major challenges in vehicular traffic environments. The route coupling increases channel contention resulting in video packet collision. In this context, this paper proposes an Interference-aware Multipath Video Streaming (I-MVS) framework focusing on link and node disjoint optimal paths. Specifically, a multipath vehicular network model is derived. The model is utilized to develop interference-aware video streaming method considering angular driving statistics of vehicles. The quality of video streaming links is measured based on packet error rate considering non-circular transmission range oriented shadowing effects. Algorithms are developed as a complete operational I-MVS framework. The comparative performance evaluation attests the benefit of the proposed framework considering various video streaming related metrics.

One approach to improve network capacity in future wireless networks is to deploy access points (APs) in a dense manner and employ a controller to manage these APs. Another innovation is to equip nodes with an in-band full-duplex (IBFD) radio, which allows them to transmit and receive simultaneously over the same frequency band. A key challenge, however, is interference. To this end, a link scheduler plays a critical role in ensuring the benefits of dense APs deployment and IBFD are not negated by severe interference. Henceforth, this paper proposes three centralized algorithms that aim to drain a given set of packets from links in minimum time. We have compared these algorithms against a schedule, where links transmit independently, and an algorithm that schedules links at slot boundaries. We studied the impact of varying node densities, transmission power, and signal-to-interference-plus-noise ratio thresholds on the link schedule. Our results show the overall completion time can be reduced by 68% as compared to scheduling links individually. Moreover, our algorithms reduce the completion time by 13% as compared to scheduling links on a slot-by-slot basis.

Side-effect modulation (SEM) has the potential to be a significant source of interference in future visible light communication (VLC) systems. SEM is a variation in the intensity of the light emitted by a luminaire and is usually a side effect caused by the power supply used to drive the luminaires. For LED luminaires powered by a switched mode power supply, the SEM can be at much higher frequencies than that emitted by conventional incandescent or fluorescent lighting. It has been shown that the SEM caused by commercially available LED luminaires is often periodic and of low power. In this paper, we investigate the impact of typical forms of SEM on the performance of optical OFDM VLC systems; both ACO-OFDM and DCO-OFDM are considered. Our results show that even low levels of SEM power can significantly degrade the bit-error-rate performance. To solve this problem, an SEM mitigation scheme is described. The mitigation scheme is decision-directed and is based on estimating and subtracting the fundamental component of the SEM from the received signal. We describe two forms of the algorithm; one uses blind estimation, while the other uses pilot-assisted estimation based on a training sequence. Decision errors, resulting in decision noise, limit the performance of the blind estimator even when estimation is based on very long signals. However, the pilot system can achieve more accurate estimations, and thus a better performance. Results are first presented for typical SEM waveforms for the case where the fundamental frequency of the SEM is known. The algorithms are then extended to include a frequency estimation step and the mitigation algorithm is shown also to be effective in this case.

The outage probability of an interference-limited linear vehicular ad hoc network (VANET) with random multiple access protocol is studied in this paper. All nodes in the VANET, including the intended transmitter-receiver pair and the interferers, are assumed to form a homogeneous Poisson point process. Communications between any two nodes in the network are carried out by using nodes between them as relays. For a given network section, more nodes between the source and the destination means more relays, thus a stronger signal component due to smaller pathloss between two neighboring nodes. Meanwhile, more nodes generate more mutual interference. A random multiple access protocol, where each node transmits with a certain probability, is adopted to reduce interference. To characterize the competing effects between pathloss and interference, we derive analytically the upper and lower bounds of the outage probability for a cluster of nodes over a fixed section of the network under the interference-limited environment. The outage probability bounds are derived as explicit functions of various system parameters, including the pathloss exponent, node mobility, transmission probability, and cluster size. Optimum designs are then performed to minimize the outage probability with respect to several system parameters, such as the node density, cluster size, and node mobilities.

Cellular networks are constantly lagging in terms of the bandwidth needed to support the growing high data rate demands. The system needs to efficiently allocate its frequency spectrum such that the spectrum utilization can be maximized while ensuring the quality of service (QoS) level. Owing to the coexistence of different types of traffic (e.g., real-time (RT) and non-real-time (nRT)) and different types of networks (e.g., small cell and macrocell), ensuring the QoS level for different types of users becomes a challenging issue in wireless networks. Fractional frequency reuse (FFR) is an effective approach for increasing spectrum utilization and reducing interference effects in orthogonal frequency division multiple access networks. In this paper, we propose a new FFR scheme in which bandwidth allocation is based on RT/nRT traffic classification. We consider the coexistence of small cells and macrocells. After applying FFR technique in macrocells, the remaining frequency bands are efficiently allocated among the small cells overlaid by a macrocell. In our proposed scheme, total frequency-band allocations for different macrocells are decided on the basis of the traffic intensity. The transmitted power levels for different frequency bands are controlled based on the level of interference from a nearby frequency band. Frequency bands with a lower level of interference are assigned to the RT traffic to ensure a higher QoS level for the RT traffic. RT traffic calls in macrocell networks are also given a higher priority compared with nRT traffic calls to ensure the low call-blocking rate. Performance analyses show significant improvement under the proposed scheme compared with conventional FFR schemes.