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Research on drones becomes vigorous not only for single drone but also drone fleet, which operates multiple drones in a formation. To widen the applicability of drone fleet, high positioning accuracy and low latency are required. Most drone products or research use the Global Positioning System (GPS) for positioning, but the accuracy is insufficient for performing various drone missions in dense or indoor environments. In this paper, we present a novel Ultra-wideband (UWB) positioning system that uses an out-of-band network for control channel. Each UWB module serves as a remote sensor for detecting and positioning multiple drones. Unlike traditional anchor-tag based UWB ranging, all nodes in the proposed system have no distinction between the roles of anchor and tag by utilizing enhanced multidimensional scaling (MDS). We practically implemented our proposed system and evaluated the system with numerical experiments. Through the numerical analysis, we have found that the proposed system provides enough accuracy and low latency to be applied to the drone fleet.

To efficiently use frequency resources, the next 6th generation mobile communication technology must solve the problem of out‐of‐band emission (OoBE) of cyclic prefix (CP) orthogonal frequency division multiplexing (OFDM), which is not solved in 5th generation technology. This study describes a new zero insertion technique to replace an existing filtering scheme to solve this internal problem in OFDM signals. In the development of the proposed scheme, a precoder with a two‐dimensional structure is first designed by generating a two‐dimensional mapper and using the specialty of each matrix. A spectral shaping technique based on zero insertion instead of a long filter is proposed, so it can be applied not only to long OFDM symbols, but also very short ones. The proposed method shows that the transmitted signal is completely blocked at the bandwidth boundaries of signals according to the current standards, and it is confirmed that the proposed scheme is ideal with respect to bit error rate (BER) performance because its BER is the same as that of CP‐OFDM. In addition, the proposed scheme can transformed into a real time structure through vectorizing process with minimal complexity.

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.

A compact microwave lowpass filter with sharp selectivity and wide stopband based on tilted rectangular slots is proposed in this paper. The developed prototype filter is based on the log periodic theory, where tilted log-periodic rectangular slots are studied for the first time. Effects resulting from the tilted slots on the performance of the studied filter are discussed and conclusions are drawn. A prototype of the proposed lowpass filter was fabricated and measured. The measured results show that the lowpass filter features a high selectivity and a wide suppression band from 4.05 GHz to 24.91 GHz under a level of 19.2 dB. Both measured and simulated performances are presented with good consistency.

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.

A compact dual-mode balun bandpass filter with improved out-of-band performance is proposed based on a ring resonator. In order to excite the two degenerate modes and obtain filtering balun performance, three parallel-coupled lines are placed at three excitation ports along the ring resonator. By properly arranging the angles between the excitation arms, four transmission zeros can be realized to improve stopband performance. Finally, a prototype of the designed balun bandpass filter is implemented and fabricated. The measured results show a good agreement with those obtained from the simulation, thus verifying our proposal with good in-band filtering and out-of-band performance.

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 paper presents a novel frequency selective surface (FSS) structure with miniaturized, rapid band edge, ultra-wideband (UWB) passband, and UWB out of band shielding. The proposed FSS is formed by using two air foam layers to cascade three single layers with the unit cell dimension in 6mm $\times 6$ mm( $0.023\lambda \times 0.023\lambda $ . The corresponding equivalent circuit models are developed for interpretation of the physical mechanism and formulate the relevant design equations. Finally, a prototype of the proposed structure is fabricated and measured to verify the full-wave simulation and theoretical analysis results. The measured results show the proposed FSS has a −3 dB passband from 1.17 GHz to 7.08 GHz and a −10 dB stopband from 7.34 GHz to 15.0 GHz. The corresponding relative bandwidths calculated from the measured results are 143.3% and 68.6%, respectively, which exhibits the stable performance against the variation of the incident angles from 0° to 45° for both TE and TM polarizations. All these results demonstrate that the proposed FSS is suitable for the actual miniaturized EMI shielding scene application.

Infrastructure-as-a-Service clouds provide out-of-band remote management of the systems in virtual machines (VMs). This management method enables users to manage their systems even on several types of failures inside VMs. In this method, users access virtual devices of their VMs, but virtual devices are not sufficiently protected against untrusted cloud operators. For secure out-of-band remote management, previous work securely runs shadow devices outside an untrusted virtualized system using nested virtualization. However, the states of shadow devices are lost during VM migration. In this paper, we propose USShadow for continuing secure out-of-band remote management after VM migration. USShadow enables the migration manager inside the virtualized system to transparently and securely save and restore the states of shadow devices outside it. We have implemented USShadow, which supports Xen and KVM as virtualized systems. Then, we confirmed that USShadow could continue virtual serial console and that the migration overhead was negligible., 2020 IEEE 13th International Conference on Cloud Computing (CLOUD 2020), 18–24 October, 2020, Beijing, China（オンライン開催に変更）

“Time domain gating” used in the stepped-frequency radar cross section (RCS) measurement causes the inaccurate frequency domain data, especially at two ends of the band. This paper proposes a spectral extrapolation method for improving the measured RCS at two ends of the band more exactly. The core idea is: the measured frequency domain data are extrapolated to obtain the unknown value out of band with an auto-regressive model (AR model). The parameter in the AR model is calculated by the maximum entropy spectral estimation algorithm. Therefore, the span of the original band is extended, and both ends of frequency on the original band are inside the range of the new band. If the time domain gating is adding to the new band, the precision at two ends of the original band can be greatly improved. The simulation and experimental results show that more effective frequency domain data near the two ends of the band can be predicted by using the spectral extrapolation method, and the maximum error at the ends of the original band is less than 1dB after extrapolation, so it can ensure the accuracy of RCS measurement over the whole frequency band.

This paper presents a patch antenna array topology for Simultaneous Wireless Information and Power Transfer (SWIPT) applications. The resulting Double Patch Antenna Array (DPA) is composed of two patch antennas operating at different frequencies and fabricated on a unique substrate. One of the patches operates at the 1.8 GHz mobile communication band and is used for wireless communication, while the other one operates at the 2.4 GHz Industrial, Scientific, and Medical (ISM) band, and is used for Radio Frequency Energy Harvesting (RFEH). The analyzes and measurements carried out have shown that the adopted topology has satisfactory performance for communication, with a gain of 1.5 dBi, and for out-of-band energy harvesting, with a Vout of 160 mV at 2.45 GHz. These results indicate this approach as a promising strategy for low-power wireless applications.

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.

An inspired metamaterial-based highly efficient monopole antenna displaying wide-/dual-band resonances along with self-filtering properties is presented. The monopole has high out-of-band suppression characteristics that lead to very close to 0 dB band-stop between the antenna dual resonant bands. The antenna operates at the two WLAN services of 2.65–3.25 and 5–7 GHz with stopband with total reflection at 4.5 GHz. The designed filtering characteristics are based on current coupling for the dual-band functions and current neutralization for the stopband function. Moreover, the proposed antenna has a very high radiation efficiency of 97 and 99% at 3 and 6 GHz, respectively. Furthermore, the proposed antenna exhibits an omni-directional radiation pattern with coplanar waveguide feed for simple integration with passive/active devices. Moreover, the antenna properties are achieved with a compact antenna size (30 × 30 mm2). With all presented results, the proposed antenna is very competitive over recent relevant antennas. In addition, a very good agreement between theoretical, full-wave simulations and measurements is achieved.

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.

In this letter, a self-balanced wideband patch antenna fed with a U-resonator is proposed to realize sidelobe reduction, even-mode suppression and bandwidth enhancement. Initially, a rectangular slot is embedded at the center of patch to interrupt and reshape its out-of-phase current, by which sidelobe radiation is significantly reduced. Then, a U-resonator is introduced at the bottom to improve the radiation performances of the resultant antenna in two ways. First, the half-wavelength U-resonator can differentially feed the patch and suppress the even mode of the radiating patch, so as to realize stable broadside radiation with no need of additional phase shifters or baluns. Second, an additional resonant mode is generated by the U-resonator, contributing to wider bandwidth. The simulated and measured results demonstrate that its impedance bandwidth is dramatically enhanced to 60% under triple resonance. Besides, improved radiation performance with low sidelobe level and more consistent beamwidth are realized, while the gain response is nearly flat in operating band and effectively rejected out of band.

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.

This article describes a dual-band diffusive metasurface-based reflector, with a specular reflection band together with two sidebands which exhibit low radar cross-section (RCS). A rhombus-shaped patch-ring type of polarizer with dual-band characteristics is chosen as the fundamental unit cell. The polarizer and its mirror structure have opposite phases in the polarization-rotating bands, while their phase is the same in the reflection band, which is juxtaposed in-between the middle of the two polarization-rotating bands. The designed metasurface is constructed, based on the phase cancellation theory, by arranging arrays of these two unit cells in a two-dimensional pattern. The measured results show that the realized metasurface-based reflector achieves a high-efficiency specular window from 26.2 to 38.8 GHz together with two low-RCS sidebands from 18.18 to 24.6 GHz and 40.61 to 56.4 GHz. The proposed diffusive metasurface can be potentially used as a reflector for reflector antennas, which provides a highly efficient in-band radiation together with low backscattering out-of-band.

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.

This thesis has been carried out on behalf of the department of Digital Services - SDI at Ericsson. Ericsson Software Defined Infrastructure (SDI) is a telco grade hardware management solution for cloud infrastructure. In datacenter deployments, the extra management equipment needed by the solution becomes insignificant due to the amount of equipment it manages. But the closer to the cloudedge you get, the smaller in size the deployments become, thus making the management equipment an ever-increasing share of the total deployment seize leading to inefficient resource utilization, so called overhead. Especially with Distributed Radio Access Networks (RAN) many small deployments, often only consisting of a single compute-server used to process radio, will be deployed at radio sites and/or in buildings around cities to deliver cell service. In this type of usage, the overhead of equipment management builds up cumulatively due to the numerous amounts of deployments. This overhead leads to excessive maintenance, power usage, space needs for equipment, costs, and electronic waste. The goal of this thesis was to evaluate how to reduce the overhead of equipment management in a scenario involving numerous small-capacity widely-distributed sites which are common in the 5G telco cloud. The idea was to determine if the overhead could be reduced by exploiting Baseboard Management Controllers (BMC), this was tested by designing a low-footprint and lightweight proof of concept equipment management solution and implementing a prototype of it. By testing, verifying, and analyzing the proof-of-concept solution, it was concluded that by exploiting the BMC to run a custom software service that phoned home to a centralized management server it was possible to drastically reduce the overhead in such scenarios. It also became clear that BMCs could have even more usage areas and provide even greater value if support to run third partyapplications existed among them. Detta examensarbete har utförts på uppdrag av avdelningen Digital Services - SDI på Ericsson. Ericsson Software Defined Infrastructure (SDI) är en hårdvaruhanteringslösning av telekomkvalitetför molnifrastruktur. I datacenterinstallationer blir den extra hanteringsutrustning som behövs av lösningen obetydlig på grund av mängden utrustning den hanterar. Men ju längre ut till molnkanten du kommer, desto mindre blir storleken på installationerna, vilket gör att hanteringsutrustning blir en ständigt ökande andel av den totala installationsstorleken som leder till ineffektivt resursutnyttjande, så kallat overhead. Speciellt med Distribuerade Radio Access Nätverk (RAN) så kommer många små installationer, ofta endast bestående av en enda server som utför radiolänksberäkningar, att vara fysiskt utplacerade vidbasstationer och/eller i byggnader runt städer för att leverera och tillhandage mobiltjänster. Vid denna typ av användning ökar overheadet för utrustningshanteringen kumulativt på grund av antalet installationer. Detta overhead leder till mer underhåll och elektroniskt avfall, större utrymmesbehov för utrustning samt högre strömförbrukning och kostnader. Målet med detta examensarbete var att utvärdera hur man kan minska overheadet hosutrustningshantering när det tillämpas på ett stort antal, små decentraliserade distribuerade installationer, vilket är förekommande i telekommoln. Idén var att undersöka om overheadet kunde minskas genom att utnyttja Baseboard Management Controllers (BMC), detta testades genom att designa en liten och lättviktigt konceptlösning för utrustningshantering samt implementera en prototyp av den. Genom att testa, verifiera och analysera konceptlösningen drogs slutsatsen att det var möjligt att drastiskt minska overheaden i sådana scenarion genom att utnyttja BMC att köra en egen mjukvarutjänst, som automatiskt anslöt till en central hanteringsserver. Genom arbetet blev det också tydligt att BMC:er skulle kunna ha ännu fler användningsområden och ge ännu större värde om stödet för att köra tredjepartsapplikationer på dem var mer utbrett

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.

We present a tunable LNA for software defined radio based on a compact, tunable transmission line (CTTL) element. The CTTL acts as a passive, widely tunable LC resonance in a cascoded, common source LNA to implement an instantaneously narrowband, multi-octave tunable LNA. The resulting circuit, fabricated in 65nm CMOS, is tunable from 3.5-20GHz, and consumes 12 mW with gain >12dB, ≥ -9.6dBV in-band OP1dB, and OOB B1dB up to 31dB higher than the in-band B1dB due to the CTTL-tuned LC filtering. The CTTL-tuned LNA represents a more blocker-tolerant approach to achieving high frequency, software-defined LNAs without significant compromises in other LNA performance metrics.

This work provides a synthesis perspective to the design of dual-band acoustic wave (AW) filtering devices through the parallel connection of two independent ladder filters. A precise consideration of the reflection phase at both ports of the filter is needed to allow the two filters to be connected together without destroying their responses. On the other hand, such a filter will depict a clear distortion in the out of band regions if compared to the individual responses of the two ladder filters. It is triggered by the fact that each AW filter acts as a capacitive cross-coupling to the other. This degradation has been observed in a commercial filter and can be explained thanks to the synthesis. Additionally, this work introduces an approach to design not only dual but also triple and quadruple band devices using the same parallel connection approach.

This Letter proposes an approach to develop a spoof surface plasmon polariton (SSPP) transmission line (TL) by loading short-circuited (SC) shunt stubs. Lower out-of-band rejections can be flexibly controlled without affecting the upper cutoff frequency by independently modifying the stubs. Dispersion analysis of the SSPP unit is realized by theoretical calculation and circuit simulation to predict the upper cutoff frequency of the proposed SSPP TL simultaneously. Also, parametric sweeping of the SC shunt stubs is performed based on circuit simulation to investigate their impacts on the lower and upper out-of-band rejections of the proposed SSPP TL. In addition, electric field distributions of different types of TLs are simulated and compared to study the transmission characteristics of the proposed SSPP TL. The lower cutoff frequency can be flexibly tuned in a wide range, from 1.2 to 2.1 GHz, in the simulations. The measured 3-dB fractional bandwidth is about 128.1%, covering a range from 1.19 to 5.43 GHz. The numerical and experimental results are compatible, which verifies the feasibility of the proposed approach. This approach can offer more convenience and flexibility for controlling the rejections of the SSPP by introducing up to four tuning parameters. More importantly, the proposed SSPP TL avoids using the substrate integrated waveguide (SIW) technique, which shows the potential to decrease the transverse width ( 0.44 λ g ), especially at lower frequencies (e.g., 1.2 GHz), and to reduce the complexity in designing the high-efficiency transition. This work paves the way for the development of novel SSPP-based microwave devices.

A dual-mode stacked patch antenna with upper out-of-band suppression using FR4 and the substrate integrated suspended line (SISL) technology is proposed in this paper. A driven patch with a slot and a parasitic patch constitute the proposed antenna. The driven patch generates the main resonance point at 3.45 GHz. The utilization of the parasitic patch not only broadens the impedance bandwidth of the patch antenna but also introduces extra resonance points in-band and a high-band radiation null. Due to etching a slot on the driven patch, the impedance matching is improved and dual modes in the band are obtained. As a result, the bandwidth from 3.28 GHz to 3.65 GHz is obtained for 5G applications, 8.68 dBi is achieved for the realized gain of the antenna. Besides, the high-band radiation null is 3.77 GHz and the upper suppression level is better than 15.4 dB.

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 letter proposed a characteristic mode cancellation method for design of an antenna radar cross section (RCS) reduction. Two kinds of subarrays whose unit cells are composed of a square patch with a circle hole and a cross patch, respectively, are designed. With the characteristic mode theory, the currents represented by the characteristic modes of two subarrays flow in an opposite direction. By arranging two subarrays into a checkerboard patterned array, cancellation of their characteristic modes is achieved and, thus, the resultant RCS of the whole array is greatly reduced. The checkerboard array is integrated with a microstrip antenna to reduce its RCS. The simulated and measured results are in good agreement and show that with the checkerboard array, the operating band of the reference microstrip antenna covering 8.32–9.32 GHz keeps unchanged, and the −10 dB broadband RCS reduction both in band and out of band of the microstrip antenna is from 6.4 to 21.4 GHz with an in-band gain increase of 1 dB.

An improved loading method of checkerboard-based linear polarisation conversion metasurface (PCM) is proposed for gain enhancement and wideband radar cross-section (RCS) reduction of the circularly polarised patch antenna (CPA). The proposed metasurface consists of a checkerboard arrangement of PCM and its mirror unit cells, and an improved loading method is used to rearrange the PCM unit cells around the radiating patch. The PCM unit cell is composed of a metallic pattern on the top and bottom surface covered with metal. A wideband RCS reduction is realised by achieving 180° cross-polarisation reflection phase difference between the two neighbouring PCM unit cells and gain enhancement is achieved by the coherent superposition of energy in the far-field between the radiating patch and PCM cells. Simulated and measured results depict that the operating bandwidth of CPA and the proposed antenna is 12.6-13.76 GHz. The peak gain of the proposed antenna is 3.5 dB higher than the CPA and 3-dB axial ratio bandwidth of the designed antenna is 200 MHz. The proposed antenna achieves significant RCS reduction in the frequency range of 9.6-22.6 GHz with maximum in-band RCS reduction of 21 dB and maximum out of band RCS reduction of 34 dB.

This paper identifies two energy saving opportunities of Wi-Fi interface emerged during smartphone’s screen-off periods. Exploiting the opportunities, we propose a new power saving strategy, BackPSM, for screen-off Wi-Fi communications. BackPSM regulates client to send and receive packets in batches and coordinates multiple clients to communicate at different slots (i.e., beacon interval). The core problem in BackPSM is how to coordinate client without incurring extra traffic overheads. To handle the problem, we propose a novel paradigm, Out-of-Band Communication (OBC), for client-to-client direct communications. OBC exploits the Traffic Indication Map (TIM) field of Wi-Fi Beacon to create a free side-channel between clients. It is based upon the observation that a client may control $1 \rightarrow 0$ appearing on TIM bit by locally regulating packet receiving operations. We adopt this $1 \rightarrow 0$ as the basic signal, and leverage the time length in between two signals to encode information. We demonstrate that OBC can be used to convey coordination information with close to 100% accuracy. We have implemented and evaluated BackPSM on a testbed. The results show that BackPSM can decode the traffic pattern of peers reliably using OBC, and establish collision-free schedules fast to achieve out-of-band coordination of client communications. BackPSM reduces screen-off energy by up to 60% and outperforms the state-of-the-art strategies by 16%–42%.

The NAVigation with Indian Constellation (NavIC) system contributes navigation solution all time during all weather conditions, anywhere within India and a region extending about 1500 km around India. The dual-band NavIC system uses the L5 and S bands for navigation. The existence of real-time Wi-Fi signal generates out of band radio frequency interference (RFI) to the S-band signal of NavIC. This interference has been perceived at particular frequencies of the S-band signal of NavIC and the reduction algorithm is proposed for this kind of interference which is based on wavelet packet decomposition. The exact spectral location of the RFI is identified and only affected interfered wavelet coefficients are processed to achieve interference reduction. The results have proven a significant amount of reduction of Wi-Fi interference in the S-band signal.

Millimeter-wave (mm-wave) communication has been widely applied in the small cellular networks, and it is not difficult to find that mm-wave plays an important role in improving the capacity and data transmission rate of the 5G network systems. Nevertheless, mm-waves also have some disadvantages, such as large propagation loss and weak penetration blockage. Although the extremely high direction of the mm-wave can compensate for the propagation loss, highly directional transmissions of the mm-wave result in conventional omnidirectional transmission cell discovery schemes may fail in mm-waves; thus, we need to redesign the cell discovery scheme of mm-wave. In addition, the overhead of mm-wave cell discovery is also large. In order to reduce the overhead and provide a reasonable solution for the mm-wave base station (BS) discovery, we propose an analysis framework that utilizes out-of-band (OOB) information assistance. First, we consider the BS discovery problem as a hypothesis test problem. We analyze the statistical properties of the generalized logarithm likelihood ratio detector and study the detection performance of the detector. Through analysis and calculation, we are able to find that the OOB scheme can not only improve the detection performance but also reduce the system overhead. Then, we also analyze the performance of the OOB scheme in the case of multiple UEs. Finally, we use the angle information provided by the OOB information to predesign the mm-wave codebooks to achieve the optimal expected mode. Analysis of the simulation results demonstrates the effectiveness of the OOB information-assisted scheme.

Electromagnetic phase conjugation provides an appealing path toward communication and target localization in dynamic media such as the earth's atmosphere. However, realizing phase conjugation-based devices has proven difficult because of the inherent complexity of systems that employ receivers and transmitters working on the same band. In this letter, we propose the concept of out-of-band phase conjugation in which the frequency of the phase conjugated wave is an integer multiple of the incident wave frequency. Remarkably, the out-of-band phase conjugated wave maintains the autofocusing property that makes phase conjugation so powerful and opens the door to imaging technology effective in random and dynamic media.

© 2018 Elsevier Ltd Model-based system inversion is a technique which allows reconstructing the forces applied to a structure and the corresponding system response using data obtained from a limited number of sensors and a dynamic model of the structure. Very often, modally reduced order models are used in system inversion, hereby reducing the number of modes to reduce the computational cost. This paper shows that the model order reduction can lead to large estimation errors in model-based system inversion. These errors are due to the disregarded quasi-static contribution of the out-of-band modes. Existing techniques for quasi-static correction cannot be straightforwardly adopted in the state-space models which are commonly applied in recursive system inversion. This paper therefore presents a novel computationally efficient approach where the quasi-static contribution of the disregarded modes is accounted for in the state-space model by means of dummy modes. The presented approach is validated using data obtained from a full-scale experiment on a footbridge. The results show that the proposed correction of the model significantly increases the estimation accuracy, as can be seen from the significant reduction in the error on the estimated forces. ispartof: MECHANICAL SYSTEMS AND SIGNAL PROCESSING vol:115 pages:173-187 status: published

A method combining characteristic mode analysis and shorting pins is presented to reduce out-of-band mutual coupling of linearly polarized rectangular microstrip antennas. Virtual feeds are applied to the antennas for depicting the contributions of each mode to the normal operation and mutual coupling of the antennas. Expressions of the modal self and mutual impedances are deduced for coaxial probes that represent the electric current excitation. Shorting pins are used to suppress specific modes with large modal mutual impedance and the suitable positions are suggested by the eigenfield distributions. Normal operation of the antennas is hardly affected by the shorting pins. The numerical and experimental results are presented for verification. Several prototypes are presented for explaining the presented method and a reduction of 5~14 dB is achieved for mutual coupling. Furthermore, it is found that the presented method is hardly affected by the distance of the antennas, which makes it useful for the design of shared aperture antennas.

Siden S.V. Out-of-band characteristics of the microstrip antenna / S.V. Siden // Proceedings of the O.S. Popov ONAT. – 2018. – № 2. – P. 13-19

Wearable Technology (WT) devices are growing at a rapid rate for their convenience and capabilities, especially in healthcare and fitness area. As the adoption of WT accelerates and a new level of ...

In this paper, we propose the design of antennas with low radar cross section (RCS) based on dispersion engineering of spoof surface plasmon polaritons (SSPPs). The antenna consists of a feeding monopole and SSPPs guiding structure placed vertically on a metal ground. By comprehensively engineering the weak and strong dispersion regimes of the SSPPs structure, the cutoff frequency of SSPPs can be made close to the upper operating frequency of the feeding monopole. In this way, the SSPPs structure serves as a high-efficiency radiator in the operating band and as a broadband absorber out of band, leading to low RCS out of band. As an example, a C -band antenna with low RCS in the X -band was designed, simulated, and measured. Both the simulation and experiment results show that the antenna can radiate in the C -band, with average gain 6 dB and fractional bandwidth 28%. In order to evaluate the RCS reduction performances, a $5\times 5$ antenna array was fabricated and the mono-static RCS was measured. The measured results show that the mono-static RCS is reduced by more than 10 dB in the whole X -band (8.0–12.5 GHz), with a maximal reduction above 30 dB. The design method provides an effective alternative to low-RCS antennas.

A novel approach to design a quad-band impedance transformer (QBIT) is presented. The primary purpose of this transformer is to match an extremely high load impedance to a source impedance of 50Ω at four distinct frequency bands with suppression of the spurious passband. The proposed QBIT is constructed using a π-shaped topology and two series microstrip-lines. The ABCD matrix method is employed to derive closed-form design formulas. The latter are employed to obtain the circuit parameters that allow for matching extremely high load impedances. For validation, two prototypes of QBIT realized to match 500Ω and 1500Ω loads are fabricated and measured. The simulated and measured transformer characteristics are in good agreement.

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.