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In this article, a novel wideband high-selectivity filtering power divider (FPD) with all-frequency absorptive performance is presented. It is based on two cascaded coupled-line (CL) sections loaded with half-wavelength open-circuit stubs and three resonator absorptive stubs. To realize all-frequency absorption of the RF-input-power, three simple absorptive stubs composed of quarter-wavelength short-circuit stubs series with resistors are applied. By introducing the CL sections with half-wavelength open-circuit stubs, the power divider (PD) is easy to realize wideband high-selectivity filtering performance and deep stopband suppression. Besides, the impedances of the open-circuit stubs can be independently adjusted to control the bandwidth. Furthermore, explicit design equations and limitations of implementations are derived and discussed. Good agreements between the simulated and measured results verify the correctness of the design theory.

New Radio-Unlicensed (NR-U) is a technology that allows fifth generation mobile networks to utilize unlicensed frequency bands, in particular, the 5 GHz band. To increase throughput, an NR-U base station (gNB) can simultaneously operate in several frequency channels within the 5 GHz band. However, the gNB cannot always transmit data through one channel and, at the same time, perform the channel access procedure in another channel due to the out-of-band emission problem, which leads to channel underutilization. As a result, the throughput of NR-U networks can heavily depend on the out-of-band emission level. In this paper, by means of simulation, the impact of out-of-band emissions on NR-U performance is studied when NR-U uses all channel access methods defined in the specification. It is shown that the out-of-band emission level affects the choice of channel access method optimal in terms of throughput. We also show that out-of-band emissions do not always have a negative impact on NR-U performance; sometimes they make it possible to achieve more than 30% throughput gain.

The competent class of fifth-generation mobile network used in NB-IoT demands for an extended and efficient massive device to a device communication system that exhibits narrow band with a focus on maximum spectrum resource usage, time and frequency synchronization and minimum out of band leakage. Filter bank multi-carrier with offset quadrature amplitude modulation (FBMC/OQAM) based systems act as a remarkable candidate for the fulfilment of application requirements of NarrowBand Internet of Things (NB-IoT) but suffer high peak to average power ratio (PAPR). Due to the overlapping of signals in the FBMC/OQAM structure, the basic SLM and PTS techniques cannot be applied on FBMC/OQAM systems. Therefore, in this work, a novel, cost-effective and low computation complexity solution SLM-MPC scheme is proposed which utilizes Model Predictive Control (MPC) algorithm for the optimization of PAPR of FBMC/OQAM transmitted signal and a significant reduction in PAPR of the FBMC/OQAM signal has been observed with negligible change in the BER of the system. The mathematical analysis is provided which justifies the simulation results and addresses the effectiveness of the proposed technique achieving a PAPR reduction of 1.61 dB and 1.2 dB for the number of sub-carriers as 128 and 256, respectively in comparison of SLM based FBMC/OQAM system.

This letter presents a power-amplifier (PA)-stabilization technique based on the low-frequency out-of-band feedback. The proposed structure replaces a conventional stability network to ensure unconditional stability at the frequencies up to the radio-frequency (RF) operating band, with the in- and above-band frequencies stabilized through the matching network design. The approach offers an alternative to inserting the lossy components in the RF signal path, which can significantly degrade the realizable in-band gain of the amplifier. The 900-MHz proof-of-concept PA based on a 10-W gallium-nitride (GaN) device is characterized under the continuous-wave (CW) and Wideband Code Division Multiple Access signal (W-CDMA) excitations and realizes 25.6-dB small-signal gain and 73% power added efficiency (PAE) at P3dB.

Noncontiguous orthogonal frequency division multiplexing (NC‐OFDM)‐based cognitive radio (CR) systems achieve highly efficient spectrum utilization by transmitting unlicensed users' data on subcarriers of licensed users’ data when they are free. However, there are two disadvantages to the NC‐OFDM system: out‐of‐band power (OBP) and a high peak‐to‐average power ratio (PAPR). OBP arises due to side lobes of an NC‐OFDM signal in the frequency domain, and it interferes with the spectrum for unlicensed users. A high PAPR occurs due to the inverse fast Fourier transform (IFFT) block used in an NC‐OFDM system, and it induces nonlinear effects in power amplifiers. In this study, we propose an algorithm called “Alternative Projections onto Convex and Non‐Convex Sets” that reduces the OBP and PAPR simultaneously. The alternate projections are performed onto these sets to form an iteration, and it converges to the specified limits of in‐band‐power, peak amplitude, and OBP. Furthermore, simulations show that the bit error rate performance is not degraded while reducing OBP and PAPR.

A spectrally encapsulated (SE) orthogonal frequency‐division multiplexing (OFDM) precoding scheme for wireless short packet transmission, which can suppress the out‐of‐band emission (OoBE) while maintaining the advantage of the cyclic prefix (CP)‐OFDM, is proposed. The SE‐OFDM symbol consists of a prefix, an inverse fast Fourier transform (IFFT) symbol, and a suffix generated by the head, center, and tail matrices, respectively. The prefix and suffix play the roles of a guard interval and suppress the OoBE, and the IFFT symbol has the same size as the discrete Fourier transform symbol in the CP‐OFDM symbol and serves as an information field. Specifically, as the center matrix generating the IFFT symbol is orthogonal, data and pilot symbols can be allocated to any subcarrier without distinction. Even if the proposed precoder is required to generate OFDM symbols with spectral efficiency in the transmitter, a corresponding decoder is not required in the receiver. The proposed scheme is compared with CP‐OFDM in terms of spectrum, OoBE, and bit‐error rate.

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

With a tremendous amount of underutilized bandwidth, millimeter wave (mmWave) communication is a promising solution to meet the increasing data-rate demands. To deal with high pathloss in mmWave frequency band, efficient large antenna arrays become crucial to provide necessary beamforming and spatial multiplexing gains. Hybrid analog/digital beamforming has been an encouraging technique in order to reduce the complexity and power consumption of large antenna arrays. In this paper, we propose a low-complexity two-stage hybrid analog/digital precoding and combining scheme for downlink multi-user multi-RF-chain mmWave systems using out-of-band spatial information to minimize the mean-squared error (MMSE) in receiving data streams. Particularly, according to sparse spatial characteristics of the mmWave channel, we utilize more efficient Grassmannian codebooks as the training codebooks to generalize a strategy of utilizing sub-6GHz spatial information for constructing multiuser mmWave communication links. The multiuser analog beamforming problem is then formulated as a weighted sparse signal recovery problem with the weights obtained from sub-6GHz spatial information. In addition, the digital precoding and combining scheme is derived using an efficient MMSE scheme for multi precoders at transmitters and combiners at receivers. Numerical results show the obvious advantages of the proposed multi-user hybrid analog/digital precoding/combining design for various practical scenarios.

From the points of spectral efficiency, low latency and massive connectivity, novel modulation and multiple access schemes have been proposed in fifth generation (5G) wireless networks. However, the combinations of multiplexing and multiple access techniques have not been widely investigated in most literatures. Therefore, we joint generalized frequency division multiplexing (GFDM) waveforms and power-domain non-orthogonal multiple access (NOMA) systems together in order to further extend the framework of multi-carrier NOMA, and also achieve performance evaluations for NOMA networks with one base station and two users. Basically, theoretical BER expressions of downlink and uplink GFDM assisted NOMA schemes are mathematically derived and then verified by simulation results. In addition, combined performance advantages, including higher achievable sum rate, lower peak-to-average power ratio (PAPR) and out of band power (OOBP) radiation, can be obtained in GFDM assisted NOMA networks.

One promising and competitive solution to keep up with the rapid growth in data traffic while at the same time addressing increasing network cost, is the efficient reuse of legacy optical fiber infrastructure. This is highly desirable as deployed single mode fibers represent a valuable asset in the network while new installations would require high additional investments. Multiband (MB) or ultra-wideband (UWB) systems, combined with high symbol rates and higher-order modulation formats, are promising solutions to capitalize the already existing fiber plants. In this contribution, we experimentally demonstrate S-C-L-band reception with 64 GBd dual-polarization (DP) 64-ary and 32-ary quadrature-amplitude modulation (QAM) while using C band components off the shelf (COTS) such as DP-IQ modulators and coherent receivers. To achieve such broadband operation with components that are not optimized for an out of band use, mitigation of the associated penalties is decisive. To this end, we apply an end-to-end electro-optical Volterra based coherent system identification followed by nonlinear digital predistortion of the transmitter. We achieve 150-nm operation bandwidth of the transmission system by performing only a single identification and predistortion at a reference wavelength of 1500 nm.

Although active interference cancellation (AIC) is an appealing approach to reduce out-of-band radiation (OBR) in multi-carrier systems without distorting data subcarriers, it usually requires a large number of reserved subcarriers to be effective. Introducing memory in AIC precoding may help alleviate this drawback in exchange for some increase in computational complexity. We propose a novel memory AIC pre-coder which, in contrast to previous schemes, minimizes OBR within a user-selectable frequency region and allows for controlling spectral overshoot.

Linearization and peak to average power ration reduction are two classical operations when non-linear power amplifiers (PA) are used. If only PA linearization is considered, the high crest factor (PAPR) of the amplified signal causes saturation when input power is higher than the PA saturation power. If only PAPR reduction is implemented alone, PA non-linearities will degrade the signal at low input backoff (IBO). It is necessary to combine the two methods in order to operate the PA with low IBO while having low in band and out of band degradations. Hybrid methods modify both the architecture of the PA for linearization purposes and the PAPR reduction of the amplified signals. In this paper two hybrid methods: Iterative Dichotomy PAPR Reduction (IDP) and Linear amplification using nonlinear components (LINC) are compared in terms of energy efficiency and implementation complexity. Two real PA models with different output saturation powers are used (45dBm and 15dBm) and the power dedicated to the algorithm implementations are quantified using an FPGA implementation. Simulation results shows that the IDP method outperforms the LINC one in terms of energy efficiency.

The paper focuses on the design of over-sampled sequence to realize pulse coded frequency modulated(PCFM) waveform based wideband beampattern synthesis. It aims to solve the problem with space-frequency nulling having spectrally contained constant modulus waveforms. Specifically, it considers to minimize the OOB spectral power of the individual code sequences, hence, the individual waveforms during the design process.

Conventional full-band (FB) digital predistortion (DPD) methods have limited linearization performances in terms of the adjacent channel power ratio (ACPR) and normalized mean square error (NMSE) when the nonlinearity of power amplifier (PA) is considerably strong. In this paper, an out-of-band (OOB) DPD scheme is proposed for the PA with strong nonlinearity. This OOB DPD scheme only suppressing the OOB nonlinear distortion, and it significantly improves the performance of ACPR even in the context of strong nonlinearity. Experimental results verify that the proposed OOB DPD can improve the ACPR performance by 20 dB when the PA is driven to the strong nonlinearity of −25 dBc ACPR. Moreover, even if the PA is driven to −20 dBc ACPR where the PA reaches saturation on the signal peak, the proposed OOB DPD still effectively suppresses the partial OOB distortion by 19 dB.

This paper presents a filtering power divider with loaded slot antennas. A fifth-degree Chebyshev filtering response with two symmetric transmission zeros are effectively implemented through a distributed configuration achieving a double-sided selectivity and broad out of band rejections. The main purpose is to design an array antenna fed by filtering power divider based on the microstrip open-loop coupled-resonators built by printed circuit board (PCB) technology. The proposed filtering antenna (Filtenna) is operating at sub-6 GHz spectrum suitable for N78-5G application. An optimized return loss, flat realized gain and steep roll-off close-to-band rejection of -12 dB, 4.5 dB and -20 dB are respectively obtained. The results are in good agreement with the design goals.

The paper proposes Out Of Band (OOB) technology to transmit service data for Free Space Optics (FSO) terminals. The requirements for this communication channel, together with the intended data for transmission, are presented. There is a comparison of LoRa, WiFi 6, Bluetooth LE 5.0 and NB-IoT technologies. After considering all the parameters, LoRa turned out to be the most suitable for the OOB channel. Next, a prototype with LoRa technology is described and is further subjected to a range test, spectral test and current consumption measurement.

The objective of this paper is to describe a number of different techniques to enhance the out-of-band performance of wide-band rectangular waveguide filters. In particular, we discuss the use of mixed inductive and capacitive (hybrid) couplings, in conjunction with a staircase configuration and E-plane T-junctions, to yield a significant improvement both in the out-of-band response and in the filter selectivity. In addition to theory, we also discuss the performance of several filter prototypes, thereby fully validating the new filter topology.

A lossy filter can be applied as the receive filter in transceiver diplexers to achieve flat passband and sharp band-edges. The out-of-band power handling capacities of lossy filters are analyzed and compared with the derived formulas of power dissipation in resonators/resistors and the compact thermal models to predict temperature rise. For the prototypes of analysis, the nonuniform-Q filter loaded with resistors, the predistorted nonuniform-Q filter and the lossy coupled filter can be used when the power up to 57.1, 68.2 and 31.8 dBm is inputted into the transmit filter, respectively, when the maximum temperature rise is set to 50 K. The power handling capacity of lossy coupled filter is quite limited by the lumped resistors.

When the fourth generation for wireless communication networks was developed, it was upgraded to provide both enhanced coverage area and higher data rates to every mobile user with lower latency. However, wireless communication system for the next-generation network will need to challenge new requirement with a greater diversity of application requirements such as ultra-high data rate, ultra-low latency, flexible use of spectrum and spectrum sharing, and battery-powered sensors that needs extremely low energy consumption, and some other control applications that want a very short round trip time (RTT). Due to problems with orthogonal frequency division multiplexing (OFDM) and next-generation demands, OFDM is not used as a promising waveform for next-generation wireless communication network. In these circumstances, alternative multiplexing schemes such as generalized frequency division multiplexing (GFDM), due to flexibility in pulse shape and single cyclic prefix in a multi-path system, GFDM is becoming common every day, making it eligible for 5G wireless technologies. GFDM looks as generalization of OFDM technique. But one of the common drawbacks of every multicarrier system is their high peak to average power ratio (PAPR). The main effect of strong PAPR is instability in the analog to digital converter (ADC) and digital to analog converter (DAC), decreased its performance and raised costs. A PAPR reduction technique such as clipping and filtering that greatly improves the efficiency compared to the initial GFDM signal PAPR. Overall peak re-growth can be reduced by using repeated clip and filter operations. Simulation is performed for this scheme to evaluate this system’s PAPR output for different values of roll-off variables.

In this letter, we propose a computationally efficient method for joint selection of cancellation carriers (CCs) and calculation of their values minimizing the out-of-band (OOB) power in non-contiguous (NC-) OFDM transmission. The proposed new CCs selection method achieves higher OOB power attenuation than algorithms known from literature as well as noticable reception performance improvement.

Millimeter wave (mmWave) MIMO communication can greatly increase the data rate, but the huge overhead of channel estimation cannot be ignored. In order to reduce training overhead, some researches based on the spatial channel correlation between the sub-6 GHz band and the mmWave band have been carried out. However, their performance is not satisfactory in distinguishing two users with close angular distance. In this paper, we propose a novel channel estimation method based on out-of-band information to enhance the accuracy of channel estimation in multiuser scenario. More specifically, based on the observation that dominant paths in mmWave band are a subset of that in sub-6 GHz band, we first obtain a coarse estimate of the spatial angle information from the sub-6 GHz band, and then, we use the discrete Fourier transform (DFT) interpolation method to refine the the estimation in mmWave band with low the training overhead. Numerical results show that, compared with the existing out-of-band information based channel estimation methods, the proposed method has better performance in multiuser scenario and the training overhead can also be reduced.

Millimeter-wave technology has proved to be one of the enabling technologies of the fifth generation of wireless networks. Despite the merits of the millimeter-wave spectrum, its directionality imposes more overhead on communication systems than the non-millimeter wave spectrum. In this paper, we propose using signaling in another frequency band to discover the paths surrounding a receiver working in the millimeter-wave spectrum. In this way, the receiver does not have to do an expensive beam scan in the millimeter wave band and repair the interrupted ongoing millimeter communication much faster by choosing the beam covering the best path discovered by another frequency band. Our experiments in various environments by millimeterwave hardware platforms show that a non-millimeter wave frequency band’s paths can be used to align the beams in millimeterwave frequency. Existing out-of-band path discovery methods typically need a specially designed hardware for scanning and can only find the single line-of-sight path. Our proposed method uses commercial off-the-shelf products to perform out-of-band scanning and discover both line-of-sight path and non-line-of-sight paths for millimeter wave communication.

Digital Predistortion (DPD) is an effective technique for Power Amplifier (PA) non-linear distortion and memory effects compensation. Different topoligies of DPD are presented in the literature. In this paper, we propose a mimetic neural network based DPD for Hammerstein power amplifier for OFDM signal with a reduction of Peak to Average Power Ration (PAPR) by Selective Mapping (SLM) method. This proposed model is compared with Real Valued Multilayer Perceptron (R-MLP). Simulation results show that the mimetic-R-MLP manifests more efficiency for PA linearization and for memory effect reduction in terms of Error Vector Magnitude (EVM) by a gain of 2 dB. It outperforms the R-MLP in terms of Mean Squared Error (MSE) for the convergence of the Neural Network (NN) and its complexity is \(23\%\) lower. The results in terms of Power Spectral Density (DSP) show also that our model compensates efficiently the out of band distortion (OOB) of the PA.

In wireless communication systems, MIMO (multiple-input and multiple-output) antenna architectures have the capability to enhance channel capacity and reliability. OFDM (Orthogonal frequency division multiplexing) is another proposed technique which is popular for high speed data transmission, robustness to frequency selective channels, low OOB (Out of Band) emission, and low PAPR (Peak to Average Power Ratio). To gain very high data rates for vast number of powerful multimedia and AI capable devices employment of mm-waves frequency bands with the above two technologies is one of the major advancements. But the problems of propagating mm-wave frequency signals are time delay, fading, propagation and scattering losses. So to attain better performance, optimizations of propagation parameters are crucial. This paper shows the effect of Path Loss (PL) models (ABG and CI) to design and analysis of 4×4 MIMO W-OFDM system using several modulation techniques (16-DPSK, 16-PSK, and 16-QAM) for 5G wireless communication. For window filters, Blackman, Hamming, and Bartlett windows have been considered.

This paper proposes a gain boosted N-path filter with improved out of band (OOB) rejection. The proposed filter contains two stages. The first stage contains a gain boosted N-path filter where two switches in each path are driven by the same clock phase. The second stage contains a two-port passive N-path filter where two switches in each path are driven by clocks of 180 degrees out of phase. The proposed design removes the limitation on OOB rejection due to switch resistance, which saves dynamic power consumption. A four path differential bandpass filter tunable from 0.2–1.2 GHz with a bandwidth of 16 MHz is implemented in 65nm CMOS technology. It achieves a maximum gain of 19.5 dB with a minimum noise figure of 2.3 dB. The maximum OOB rejection achieved is 65 dB. The minimum in-band IIP3 recorded is −4.5 dBm. The minimum third and fifth order harmonic rejection achieved is 20 dB and 27 dB, respectively. The proposed filter draws a maximum power of 16 mW from 1.2 V supply at 1.2 GHz tuning frequency.

This paper presents a frequency tunable, high dynamic range 65nm bulk CMOS downconverter operating from 9-31GHz. The design implements a topology variation of a 4 phase passive mixer which allows for sinusoidal LO drive and achieves a minimum NF of 12.5dB and out of band (OOB) blocker compression (B1dB) of -6dBm for a B1dB-NF FoM of -18.5 dB while consuming only 73mW. Should higher performance be required, a B1dB of over 4 dBm, and OOB IIP3 of 21 dBm, can be achieved using 162mW of power while maintaining noise and bandwidth performance, for a FoM of -8.5dB. To the author’s knowledge this is the highest such FoM reported for a CMOS receiver in this frequency range.

In this paper, a wideband reconfigurable receiver front-end incorporating two paths is proposed. The main path has the advantage of low noise thanks to the low noise transconductance amplifier preceding the mixer and baseband. Based on the mixer-first structure, the auxiliary path provides a high inband and out of band linearity. The inductor resonance is also designed to mitigate the baseband noise crosstalk issue. Both of two paths share a common baseband circuit and are driven by a 25% duty cycle LO generator. Simulation results in 180 nm CMOS indicate that the main path provides a low noise of 2.7 dB, while the auxiliary obtains the inband IIP3 of 9.2 dBm with f LO = 1.25 GHz.

The low-frequency and mmWave links usually co-exist in the next generation wireless terminals, where the low-frequency link is always on and the mmWave link becomes active when high rate transmission is required. Since low-frequency and mmWave channels have spatial similarities, it is feasible to utilize low-frequency channel information to reduce the beam training overhead in mmWave communications. In this paper, we propose a deep learning assisted beam prediction scheme using out-of-band information extracted from low-frequency channel state information (CSI). To overcome the inaccuracy in estimating spatial features due to small number of antennas in low-frequency band, deep learning is introduced to extract robust channel features and increase the prediction accuracy. Moreover, dedicated pre-processing algorithm and network architecture are derived to improve the performance. Simulation results demonstrate that the proposed scheme is robust to various CSI matrix sizes and signal-to-noise ratio. By exploiting low-frequency CSI, it could successfully predict the optimal beam direction to facilitate the initial beam training in mmWave communications with over 94% accuracy in line-of-sight scenarios, which can reduce the overhead of beam training significantly.

The rapid evolution of mobile communication networks is due to the large increase in the number of users. But higher throughput is not the only criterion to address the fifth generation of cellular networks. It mainly focuses on the redressal of the possible issues of the networks. The mostly found issues are lesser area of coverage, non-linear signal effects and the dispersion which is found to occur during the signal pathway. This work entails on increasing the maximum limit of coverage without signal loss. Through the usage of microcells in the proposed system, maximum limit of coverage is achieved in highly populated areas. The simulations are carried out using software MATLAB 2017a and Opti-System, in which enhanced symbol error rate plot and reduced out of band emissions power performance have been improved. Finally, the conclusion and the future scope of the work has been discussed.

International audience; For the first time, we demonstrate in this paper an intensity-modulation direct-detection (IMDD) universal filtered multi-carrier (UFMC) system through several hundred meters of multimode fiber (MMF) that can be adopted for 5G communications and beyond. The proposed system is simulated and evaluated in terms of bit error rate (BER), Q factor, out of band (OOB) emission and Peak-to-Average Power Ratio (PAPR), at a data rate of 10 Gb/s. It is shown that filtering used with UFMC reduces the OOB radiation by 40 dB compared to orthogonal frequency division multiplexing (OFDM). Moreover, we prove that UFMC gives lower values of BER than OFDM, and even if the PAPR ratio of UFMC is higher than OFDM, the gap remains small. The results also show that using a Volterra equalizer with increasing taps enables to obtain acceptable performance through the MMF in terms of BER, even with high number of excited mode groups.

This paper presents based on flexible coupling schemes using multiple quarter-wavelength resonators. Microstrip-to-slotline transitions were are used to provide external coupling to the filters. A dual-mode and tri-mode filter are designed. For the dual-mode design, a pair of quarter-wavelength resonators is used with a gap between them providing a suitable coupling coefficient. For the tri-band design, an additional resonator is coupled to the previous quarter-wavelength resonators, leading to a three-pole response within the passband. A microstrip line with a grounded resistor is added at the middle point of two output ports, leading to excellent output matching and isolation between output ports. Two design examples with dual-mode and tri-mode responses are realized with the verification using full-wave simulations.

In order to meet the explosion of connected devices with their heterogeneous applications, the upcoming 5G systems focus on the design of spectrally efficient waveforms. Universal Filtered Multicarrier (UFMC) is one of the major waveforms contenders that offers low out of band emissions, compatibility with the existing Multiple Input Multiple Output techniques as well as multiple services support. In this paper, we propose to couple UFMC with Cognitive Radio (CR) to make better use of the available spectral resources. To perform spectrum sensing for the CR, we rely on cyclostationary detection. UFMC cyclostationarity characteristics have not been researched before. Hence in the present work, we first derive the explicit theoretical m-th order cyclic cumulants of UFMC, considering a multipath channel, frequency and timing offsets. Our analysis reveals that the per-subband filtering used in this waveform produces distinctive cyclostationary signatures. Then we exploit these signatures for signal detection. The obtained results are compared to those of the well studied Orthogonal Frequency Division Multiplexing (OFDM). Detection probability of UFMC outperforms the one of OFDM specially when the used Cyclic Prefix (CP) is low.

This article proposes novel wide band stop filter topologies at C-band with simpler implementation in microstrip. The introduction interdigital resonator along with stepped impedance resonator concept is utilized for the placement of transmission zeros to achieve wideband performances. This article demonstrates fractional bandwidth of > 80% with steep skirt rate. This topology is modified further to achieve improved out of band performance. The parallel coupled section for input and output signal coupling results in improved out of band performances. The measured 3-dB bandwidth is from 4 to 10 GHz and transmission loss below 0.55 dB is achieved for both the topologies. Close analogies between simulated and measured results is obtained which are detailed in this article. The presented topologies are simpler and novel achieving the desired performances without vias.

In modern scenarios, there are several applications of OFDM, but it also has some demerits like sensitive to Carrier Frequency Offset (CFO), high Peak to Average Power Ratio (PAPR), and timing offset large. Out Of Band (OOB) and low spectral efficiency due to cyclic prefix per symbol insertion. To diminish and discard above problems, new multiplexing technique is required for next generation wireless communication i.e. GFDM. GFDM is becoming popular day by day due to flexibility in pulse shape as well as single cyclic prefix in a multipath channel and which makes it eligible for the 5th generation technology. This paper deals with an overview of a GFDM and presents a comparative study between OFDM and GFDM.

Communications in the millimeter wave (mmWave) band faces significant challenges due to variable channels, intermittent connectivity, and high energy usage. Moreover, speeds for electronic processing of data is of the same order as typical rates for mmWave interfaces, making the use of complex algorithms for tracking channel variations and adjusting resources impractical. In order to mitigate some of these challenges, we propose an architecture that integrates the sub-6 GHz and mmWave technologies. Our system exploits the spatial correlations between the sub-6 GHz and mmWave interfaces for beamforming and data transfer . Based on extensive experimentation in indoor and outdoor settings, we demonstrate that analog beamforming can be used in mmWave without incurring large overhead, thanks to the spatial correlations with sub-6 GHz. In addition, we incorporate the sub-6 GHz interface as a fallback (secondary) data transfer mechanism such that: 1) the negative effects of highly intermittent mmWave connectivity are mitigated and 2) the abundant mmWave capacity is fully exploited. To achieve these goals, we consider the problem of scheduling the arrival traffic over the mmWave or sub-6 GHz in order to maximize the mmWave throughput while delay (due to mmWave outages) is guaranteed to be bounded. We prove using subadditivity analysis that the optimal scheduling policy is based on a single threshold that can be easily adopted despite high link variations. Numerical results demonstrate that our scheduler provides a bounded mmWave delay performance, while it achieves a similar throughput performance as the throughput-optimal policies (e.g., MaxWeight).

Configuring the antenna arrays is the main source of overhead in mmWave communication systems. In high mobility scenarios, the problem is exacerbated, as achieving the highest rates requires frequent link reconfiguration. One solution is to exploit spatial congruence between signals in different frequency bands and extract mmWave channel parameters with the aid of side information obtained in another band. In this article we propose the concept of out-of-band information aided mmWave communication. We analyze different strategies to leverage information derived from sensors or from other communication systems operating at sub-6 GHz bands to help configure the mmWave communication link. The overhead reductions that can be obtained when exploiting out-of-band information are characterized in a preliminary study. Finally, the challenges associated with using out-of-band signals as a source of side information at mmWave are analyzed in detail.

This paper presents simple and compact mobile free-space optical (FSO) terminals based on a common optical path with an adaptive beamforming function to provide an enhanced Gbps out-of-band full-duplex connection between a ground control system and an unmanned aerial vehicle (UAV). The mobile FSO terminals were carefully designed considering the UAV mobility and payload and the trade-off relationship between the geometric loss and volume of the FSO terminal for a given aperture diameter. Useful parameter information, such as the geometric loss, volume, and aperture diameter are presented in detail. As the novel common optical path structure-based mobile FSO terminal has a simple structure design and less optical components, it can effectively reduce the size, weight, and power consumption for UAV mounting. The beamforming function within the proposed system improves the optical tracking efficiency between FSO terminals by varying the divergence angle (from 0 to 8.84 mrad) according to the data link length. With the help of the beamforming function, the mobile FSO terminals showed significantly improved connectivity compared to the terminals employing collimated beams and fixed angle beams. Consequently, the proposed mobile FSO terminals provide reliable 1.25-Gbps out-of-band full-duplex error-free (with a bit error rate of

Filter Bank Multicarrier (FBMC) has become popular as an alternative to OFDM (Orthogonal Frequency Division Multiplexing). However, current FBMC systems found in the literature are not as compatible with MIMO (Multiple Input and Multiple Output) as OFDM is. This is due to the presence of inherent self-interference in current FBMC structures. Current literature uses maximal spectrally efficient waveforms, which have high interference among sub-carriers, thereby requiring complex post-processing in MIMO systems. In this work, we relax the spectral efficiency and show quantitatively that both the interference and out of band ripple energy can be decreased. We analyze this interference and its effects on different modulations at various SNR (Signal to Noise Ratio) values. We observe that the interference effect is more dominant at high SNR and affects higher order modulations more significantly. Reducing the interference enables near-orthogonal FBMC designs for practical SNR values and higher order modulations while still retaining MIMO receiver structures with low design complexity. We also show that error correcting codes can mitigate the effects of this interference. In this paper, first we compare our proposed FBMC system with OFDM and then with Filtered OFDM, one of the leading waveform candidates for 5G. Our simulations reveal that there is less than 1 dB gap between OFDM and FBMC having 84% and 97% spectral efficiencies respectively, using a 4 × 4 MIMO-VBLAST for 64-QAM at 30 dB SNR. Also, a comparison with Filtered OFDM system reveals that the proposed FBMC system is computationally more efficient for 5G systems.

A UWB filtering antenna (or filtenna) with a band-notched characteristic has been proposed in this paper. A square-shaped-stepped patch UWB antenna and an inverted T--shaped bandpass filter based integrated filtering antenna (IFA) with band-notch characteristic has been designed and fabricated. The size of the proposed filtenna is the same as the UWB patch antenna. The UWB patch antenna has a bandwidth from 3 GHz to more than 14 GHz. A UWB filter having a notched band is proposed and integrated with the primarily offered square-shaped--stepped patch antenna to design an IFA for UWB wireless communication system. The filter is placed on the feeding position of the patch antenna, and the output of the filter is coupled with the radiating patch to achieved the desired result. Proposed filtenna achieves circular polarization, minimum of 14 dB out of band gain rejection, and a notched band from 5.55 to 6.98 GHz, which avoids the interference from Dedicated Short Range Communication (DSRC) applications. A wide axial-ratio bandwidth (AXBW) from 3.1 to 5.5 GHz and 7–9.8 GHz along with a maximum gain of 6.8 dBi within the operating frequency range of the proposed filtenna has been achieved.

A polarization diversity-based PON system can be an attractive network solution for the future PON system that requires high data capacity with both a large number of subscribers and longer transmission-reach. However, the state-of-polarization (SOP) inevitably rotates during the transmission through the single-mode fiber (SMF). Therefore, this system cannot ensure high data capacity owing to the SOP rotation. In this paper, we propose the out-of-band pilot-aided SOP rotation tracking technique for in the polarization diversity-based PON transmission system. The proposed technique tracks the SOP rotation by measuring the variance of the power ratio of the inserted pilot-tone at the reference polarization axis. This technique offers the advantages of a low overhead and dynamic update for SOP variation; further, it is optical control-free and transparent for data format. For the experimental demonstration of the SOP rotation compensation, the pilot insertion was firstly optimized and the correctable range of the SOP rotation was analyzed. The results of the emulation of the uplink transmission indicated that the SNR at both polarization axes could be successfully retained by compensating the SOP rotation. Under the target forward error correction limit, the SE up to 8 bit/s/Hz within single-wavelength was obtained for 60 km PON transmission.

This paper presents a low power and highly linear passive spectrum scanner based on the filtering by aliasing principle. The scanner utilizes a linear periodically time-varying circuit followed by a sampler to achieve sharp apparent filters from a continuous-time input to a discrete-time output. This paper describes the design of the scanner and provides an analysis of the expected and measured performance in the presence of circuit non-idealities. The scanner enables a DC −1 GHz spectrum scan while consuming 8 mW of power, with an out-of-band IIP3 that is better than +31 dBm across the band.

A microstrip elliptic-function Low-Pass filter (LPF) utilizing a Radial Stub (RS) is proposed having an attributes of sharp roll-off and wide rejection bandwidth. The proposed LPF is explored based on a proper ideal lumped equivalent model circuit. The proposed fabricated LPF having a cutoff frequency of 2.4 GHz are of dimension 0.505 λc × 0.217 λc (where λc is the guided wavelength at the cutoff frequency) shows a magnificent wide out of band from 3 GHz to 15 GHz at 10 dB. The filters are evaluated by design, experimental and simulation with good agreement.

This work provides a new co-design methodology of ultrawide band (UWB) low-noise amplifier (LNA) with high out of band interference cancellation. The solution consists to cascade a selective microstrip UWB bandpass filter (BPF) with the proposed 0.18 µm complementary metal–oxide–semiconductor-based LNA. Indeed, the usefulness of this co-design technique is to address the interference mitigation through the BPF and amplification function by using the LNA. The proposed solution remains powerful since the out of band interferences are well avoided with an efficient amplification performance while well fulfilling UWB requirements, i.e. good matching over a wide bandwidth from 3.2 to 10.64 GHz, 17 dB of power gain (S 21), the noise figure varies between 2.5 and 5.7 dB, and the dissipated power (P DC) is typically 16.5 mW. It is relevant to point out that the computed figure-of-merit of the proposed circuit is 29.03 which is very competitive compared with state-of-the art.

This paper presents comparative analysis between different 5G waveforms UFMC (Universal Filter Multi-Carrier) and FBMC (Filter bank Multicarrier) based on Offset-QAM with 4G system CP-OFDM (Cyclic Prefix-OFDM). The existing 4G multicarrier technology CP-OFDM has many issues. The cyclic prefix in OFDM is used to reduce the multipath effects and hence reduce ISI and ICI, but CP reduces efficient spectral usage. Also the CP-OFDM has high OOB (Out Of Band) emission with respect to adjacent side bands and has high PAPR (Peak to Average Power Ratio). So here, the two 5G waveforms UFMC and FBMC-OQAM are discussed which does not make use cyclic prefix and hence increases spectral efficiency. Also these systems consist of additional filtering process which can reduce OOB emission. Also the system performance is analysed interms of different fading channels.

Generalized frequency-division multiplexing is one of the multi-carrier modulation schemes currently under study for beyond fifth generation (B5G) cellular systems. The main characteristics of generalized frequency-division multiplexing (GFDM) are the flexible time-frequency structure of data blocks, making it customizable according to various service requirements in B5G scenarios, and the low out of band (OOB) emission, which can be achieved by means of a flexible time-domain pulse shaping of individual sub-carriers. With this motivation, a new pulse shaping filter is proposed and its benefits on the OOB emission and on the symbol error probability (SEP) are demonstrated. The eye diagram, used as a performance evaluation parameter at the transmitter, shows that the proposed pulse has better vertical sharpness than root-raised cosine (RRC) filter and, therefore, it gives better OOB emission. Along with vertical sharpness, it has better horizontal sharpness, which means that the proposed pulse has better tolerance to inter-symbol interference (ISI). The SEP performance is evaluated by means of Monta Carlo simulations in case of 16-QAM transmission over an AWGN channel. Analytical expressions of SEP are also presented.

The motivation behind Cognitive Radio (CR) is to secure the transmission of primary (licensed) user in the existence of secondary (unlicensed) users in the similar spectral territory. Orthogonal Frequency Division Multiplexing (OFDM) is a best candidate for Dynamic Spectrum Sensing (DSA), because of flexible spectrum shaping. However, main problem of using OFDM in cognitive radio is high Out Of Band (OOB) radiation that cause interference with neighboring user. Different techniques for the reduction of OOB radiation have been proposed, but it may cause inefficient use of spectrum due to insertion of Cancellation Carriers (CCs). Generalized Sidelobe Canceller (GSC) is updated method to minimize the OOB without insertion of CCs. GSC consist of two branches the signal come out from these branches of GSC gives significant minimization in the sidelobes power. This paper presents the performance of multiple GSC cascaded in serial. The simulation results show better reduction in the power of sidelobes as compared to single GSC and other traditional methods.

Cognitive Radio Network (CRN) is the optimal choice for systematic utilization of the radio spectrum. The objective behind CRN is to permit Secondary Users (SUs) to transmit their data opportunistically in the nonexistence of Primary Users (PUs). In CRN, Orthogonal Frequency Division Multiplexing (OFDM) is employed for signaling due to its efficiency and easy implementation. The drawback in using OFDM is its sidelobes that causes Out of Band (OOB) radiations, which results interference to the PU's. In order to reduce OOB radiations we have proposed Modified Generalize Sidelobe Canceller (MGSC). In our proposed technique the optimization part of the adaptive weight vector of conventional Generalize Sidelobe Canceller (GSC) is done by using Differential Evolution (DE). The effectiveness and reliability of our proposed technique is shown with the help of MATLAB simulation. Our proposed technique shows better results in comparison with existing techniques.

The standardization of the first phase 5G system in Release 15 named New Radio (NR) will soon move on to the stand-alone version with intention to bring it commercially to the market around 2020. This paper investigates the impact of power amplifier in OFDM-based waveforms including CP-OFDM, F-OFDM and W-OFDM. We first derive a mathematical model for these OFDM-based waveforms. Then we analyze the impact of power amplifier (PA) to the out-of-band (OOB) waveform, which is a critical component in the densely spectrum with different channel widths using scalable numerologies. It is shown that W-OFDM and F-OFDM are more suitable than the conventional CP-OFDM. The provided results of this paper thus facilitate knowledge of design and practice for further NR features. As the simulation results, without PA clipping, the W-OFDM and F-OFDM present better OOB characteristic than CP-OFDM, while applying PA clipping both of them show the similar performance. Additionally, another W-OFDM design with PA clipping shows advantages to implement for 5G NR waveform.