High Bandwidth Efficiency Research Articles

Analysis and Design of a Wideband Endfire Circularly Polarized Septum Antenna

A novel millimeter-wave (MMW) endfire wideband circularly polarized (CP) antenna with simple structure is reported. By introducing two symmetrical septum blades filled in the widened rectangular waveguide, the proposed antenna can obtain a 40% bandwidth for both axial ratio (AR) $S_{11} dB. The CP operating mechanism of the antenna has been explained, using a three-port structure. The parametric studies for all of the antenna parameters are carried out to estimate their influences on antenna performance. The sharp corner in the AR plot is also explained by mode analysis. Its influences on the radiation pattern, gain, and reflection coefficient at this frequency point are evaluated. The proposed antenna has been fabricated and measured. The simulation results are in good agreement with the measurement results. Furthermore, this antenna is an appropriate choice for designing a MMW high-efficiency wideband antenna array. An $8 \times 8$ array with 64 equal amplitude and phase wave ports in HFSS has been designed to evaluate the array performance, which shows that the array can achieve 40% operating bandwidth without considering the bandwidth of feeding network. The simulated aperture efficiency of the array is above 85.34% from 50 to 75 GHz.

Bounds for two static optimization problems on routing and spectrum allocation of anycasting

Elastic optical networks with optical-orthogonal frequency division multiplexing have been addressed enthusiastically for communication networks in the last decade because they result in high bandwidth efficiency. Routing and spectrum allocation (RSA) problems need to be solved when we transmit demands in an elastic optical network. This research deals with static RSA models for anycast transmission, which is one-to-one-of-many transmission in inter-datacenter networks. Two static RSA optimization models are considered. One minimizes the maximum number of spectrum slots needed to allocate given demands. The other maximizes the traffic volume of demands served under a given spectrum slot number. For both models, lower and upper bounds are developed in order to obtain exact optimal solutions. One-side bounds of the problems are evaluated by relaxing spectrum continuity constraints. For the other side bounds, several greedy algorithms are investigated. We conducted computational experiments to confirm whether relaxation problems can give tight bounds and to determine greedy algorithmic behaviors by using each of route selection criterion and each of demand ordering policies. The results show that the solutions obtained by relaxing spectrum continuity constraints are almost optimal. They also indicate that exact optimal solutions are obtained efficiently by using these bounds.

Spectrally efficient digital mobile fronthaul with discrete cosine transform and multi-band quantization.

A spectrally efficient digital mobile fronthaul (MFH) with discrete cosine transform and multi-band quantization (DCT-MBQ) is first proposed and experimentally demonstrated. In this approach, the baseband orthogonal frequency division multiplexing (OFDM) symbols are segmented into individual blocks and independently transformed by DCT to obtain a set of transform coefficients. Different from digitizing each OFDM sample with the same number of quantization bits (QBs) in previous digital MFH, MBQ is introduced to separately digitize different parts of the coefficients with different numbers of QBs according to the significance of these coefficients. Furthermore, the part of transform coefficients with little significance is discarded. Thus, the total number of required QBs for digitizing an OFDM symbol can be greatly reduced and, thereby, high bandwidth efficiency can be achieved. In the experiment, the proposed DCT-MBQ-based digital MFH transmission is demonstrated over a 25Gb/s four-level pulse amplitude modulation intensity modulation-direct detection optical link supporting up to 16×100 MHz 5G new radio carriers with 1024 QAM, achieving an error vector magnitude of 0.65%. The equivalent common public radio interface rates from 55 to 158Gb/s are supported.

ICI suppressing scheme in OFDM systems over multipath fading channels

A novel scheme with the method of subcarrier modulation is proposed. Comparing with the other existing self-cancellation methods, the proposed scheme not only has the advantages of good inter-carrier interference (ICI) suppression capability and high bandwidth efficiency, but also shows a better bit error rate performance over multipath fading channels.

On-demand route discovery in a unicast manner.

While having high bandwidth-efficiency, the ad-hoc on-demand distance vector (AODV) routing protocol suffers from high signaling overhead due to route request (RREQ) messages flooding, especially when the node density and the number of connections are increased. In order to resolve this broadcast storm problem of the AODV in a high node density mobile ad-hoc network, we propose a geographical on-demand route discovery scheme. Assuming a known location of the destination, the RREQ of the proposed routing protocol is propagated in a unicast manner by employing a novel parsing mechanism for possible duplicate RREQs. The routing overhead of the proposed routing protocol is greatly robust to the node density change. We derive the node density required for the proposed routing protocol to keep the same connectivity as the AODV under the circumstance where the nodes are uniformly distributed. In addition, we present an imaginary destination consideration method to incorporate the uncertainty of the destination’s location due to mobility. Computer simulations show that the proposed scheme enables the RREQ propagation to cover 95% of the one-hop communication area centered at the originally known location of the destination without sacrificing the unicast feature.

Digital Signal Processing for High-Speed Fiber-Wireless Convergence [Invited

We review recent advances in the field of fiber-wireless convergence to better support cloud radio access networks via high-speed low-latency mobile fronthaul between remote radio units and baseband units. We also present how digital signal processing (DSP) may be used to support both common public radio interfaces (CPRI) in a point-to-point architecture and Ethernet-based CPRI in a point-to-multipoint architecture to achieve high bandwidth efficiency and low processing latency. The use of DSP-enabled next-generation passive optical networks (PON), such as 50 Gb/s PON, to support mobile fronthaul in a resource-efficient manner will also be discussed.

Video denoising for security and privacy in fog computing

SummaryTo reduce heavy noise from degraded video in low or predictable latency and preserve privacy, a powerful and efficient video denoising algorithm is proposed based on fog computing for Visual Internet of Things. The conventional method is to remove noise in the cloud; however, this may overload computation and communication and raise security and privacy issues. The proposed denoising algorithm is distributed to heterogeneous devices at network edges to preserve privacy and avoid security risks as noise can be reduced in the fog rather than the cloud. To address the problems of latency, communication rate, and extremely heavy noise, structure registration, inter‐frame and inner‐frame filters, and distribution compensation are applied in the proposed algorithm. A scheme for encrypting the denoised data at network edges is provided so that security and privacy issues may be avoided during transmission and storage. Compared with other denoising approaches under extremely heavy noise conditions, the experimental results demonstrate that the proposed approach achieves superior denoising performance in terms of peak signal‐noise ratio and visual quality at low computational cost, high bandwidth efficiency, and low‐latency response in a fog computing manner.

Codesigned Wideband High-Efficiency Filtering SIW Slot Antenna with High Selectivity and Flat Gain Response

A substrate integrated waveguide (SIW) slot antenna with wideband bandpass filtering performance is proposed in this journal. It consists of a SIW cavity, a transverse slot, three metal posts, and a SMA connector. Three metal posts split the SIW cavity into two TE110-mode resonators. A long nonresonant transverse slot is utilized to realize a half TE110-mode resonator and generate radiation simultaneously so as to reduce the size and release the use of extra radiator. Three in-band resonance poles and a radiation null at both out-of-bands are obtained. A prototype is fabricated and measured. Measured results demonstrate the proposed antenna is with a center frequency of 4.26 GHz, a fractional bandwidth of 9.1%, a high efficiency of 93%, and flat gain response and good skirt selectivity of 270 dB/GHz and 330 dB/GHz for the lower and upper out-of-band, respectively.

Wideband high-efficiency linearized PA design with reduction in memory effects and IMD3

ABSTRACTAn analytical method is proposed to reduce the memory effects and third-order intermodulation distortions for improving the linearity of wideband power amplifier (PA). An excellent linearity can be obtained by reducing the second-harmonic output power levels and reducing the envelope voltage components in the megahertz range. An improved wideband Chebyshev low-pass matching network including the bias network is analyzed and designed to validate the proposed method. The measured results indicate that a wideband high-efficiency linearized PA is realized from 1.35 to 2.45 GHz (fractional bandwidth = 58%) with power added efficiency of 60–78%, power gain of 10.8–12.3 dB, and output power of 40.0–41.2 dBm. For a 20 MHz LTE modulated signal, the adjacent channel leakage ratios (ACLRs) of the proposed PA with digital pre-distortion (DPD) linearization are −55.7 ~ −53.9 dBc across 1.5–2.4 GHz at an average output power of 32.4–33.6 dBm. For a 40 MHz two-carrier LTE modulated signal, the ACLRs of the proposed PA with DPD linearization are −51.1 ~ −48.2 dBc at an average output power of ~30.5 dBm in the frequency range from 1.5 GHz to 2.4 GHz.

Design, simulation and analysis a microstrip antenna using PU-EFB substrate

A low cost, light weight and easy to fabricate are the most important factor for future antennas. Microstrip patch antennas offer these advantages and suitable for communication and sensor application. This paper presents a design of simple microstrip patch antenna working on operating frequency of 2.4 GHz. The designed process has been carried out using MATLAB and HFSS software by entering 2.3 for the dielectric constant of PU-EFB. The results showed that high return loss, low bandwidth and good antenna radiation efficiency of which are -21.98 dB, 0.28 dB and 97.33%, respectively.

An Optical Duobinary Downlink Access Scheme Using Low Pass Filter and its Application

In this letter, a novel optical duobinary (ODB) downlink access scheme using low pass filter was proposed. The ODB downlink signal was generated by one continuous-wave (CW) laser, one pseudo-random binary sequence (PRBS) generator, one NRZ generator, one precoder, one Mach-Zehnder modulator and one low pass Bessel filter. The downlink signal can be transmitted over 20km singlemode fiber (SMF) and successfully received. We analyzed the time-domain waveforms, optical spectrum and eye diagrams before and after downstream transmission. The simulation results show that, compared to the traditional downlink scheme, this scheme has the advantages of high bandwidth efficiency, resistance to dispersion and good reception performance.

Enhanced brain image retrieval using carrier frequency offset compensated orthogonal frequency division multiplexing for telemedicine applications

AbstractWireless technology plays a vital role in the Electronic health (e‐health) applications such as telemedicine and remote patient monitoring. One of the major challenges of telemedicine applications is ensuring adequate quality of service and realizing precise diagnosis. Telemedicine employs image fusion to enhance the quality of medical image for better diagnosis. However, the transmission of medical image needs high data rate and bandwidth. Due to the robustness to multipath fading, high data rate transmission capability, high flexibility, high bandwidth efficiency, and easy implementation using fast Fourier transform, an orthogonal frequency division multiplexing (OFDM) is the suitable technique for medical image transmission in telemedicine applications This paper is focused on improving the quality of the fused brain image transmission over OFDM based telemedicine service using comb type pilot based carrier frequency offset compensation. The simulation results show that the proposed method offers better performance in terms of mean squared error, Euclidean distance, peak signal to noise ratio, bit error rate, carrier to interference ratio, and computational complexity.

LTE Multimedia Broadcast Multicast Service Provisioning Based on Robust Header Compression

One important issue that confronts network service providers is the need to provide reliable multimedia data service efficiently over cellular networks for a large number of subscribers under dynamic channel conditions. In long term evolution (LTE) networks, multimedia broadcast multicast service (MBMS) is a bandwidth efficient data service to simultaneously support multiple users at high bandwidth efficiency. In this paper, instead of considering spectrum resource allocation, we investigate MBMS provisioning for each mobile user based on the higher layer robust header compression (ROHC) consideration in response to user channel quality to reduce packet losses. We formulate a profit maximization problem for two different MBMS channel models and further propose a new MBMS assignment scheme for each user to be assigned a target MBMS with optimal ROHC parameters. We further develop a dynamic programming algorithm for user assignment and ROHC parameters optimization to achieve maximal profit with high spectrum resource utility. Our numerical results demonstrate substantial profit gain achieved by the proposed method in LTE systems.

Turbo Trellis-Coded Differential Chaotic Modulation

In this brief, a novel turbo trellis-coded differential chaotic modulation (TTC-DCM) system is proposed, where parallel concatenated trellis codes are combined with the M-ary differential chaotic shift keying (M-ary DCSK) scheme. An extrinsic information transfer chart is employed to analyze the convergence over additive white Gaussian noise channel and multipath Rayleigh channels. Simulation results show that the new scheme can obtain considerable coding gains without impairing the bandwidth efficiency in comparison with the M-ary DCSK scheme and the trellis-coded differential chaotic modulation scheme. Moreover, compared to the direct-sequence spread-spectrum turbo trellis-coded modulation scheme, TTCDCM has lower complexity and better robustness in the absence of channel state information over multipath Rayleigh channels. Overall, because of the merits of promising performance, high bandwidth efficiency, robustness to poor channel conditions, and an easy-to-implement property, the TTC-DCM scheme is suitable for bandlimited communication applications under poor channel conditions.

Complementary Coded Scrambling Multiple Access and Its Performance in Downlink MIMO Channels

In a traditional complementary coded CDMA (CC-CDMA) system, signals are spread using the direct sequence (DS) technique to suppress multipath interference (MI) and multiple access interference (MAI). However, DS spreading suffers from very poor bandwidth efficiency. This paper proposes a scrambling-based CC-CDMA system, namely complementary coded scrambling multiple access (CCSMA). A CCSMA system offers a unified platform to integrate CC-CDMA, multiple-input multiple-output (MIMO), and scrambling technique seamlessly. Utilizing complementary codes in scrambling modulation, a CCSMA system is able to suppress MI and MAI effectively. With the help of space domain scrambling, the CCSMA system offers much higher bandwidth efficiency than a CC DS-CDMA system. Bit error rate and system capacity are evaluated explicitly in this paper, verifying that CCSMA is a viable multiple access technique for providing high capacity in downlink MIMO channels.

Packaging Solution for a Millimeter-Wave System-on-Chip Radar

In this paper, a packaging solution for millimeter-wave system-on-chip (SoC) radio transceivers is presented. The on-chip antennas are realized as primary radiators of an integrated lens antenna which offer high bandwidth and high efficiency. The package concept includes a high permittivity silicon lens which serves additionally as heat sink and a quad flat no-lead package which is mountable on a standard printed circuit board (PCB). The electrical and thermal properties of the package are investigated through simulations and calibrated measurements. The concept is verified by realizing a complete radar sensor. The manufactured SoC radar frontend is soldered on a standard PCB which includes the baseband circuitry for a frequency-modulated continuous wave radar and finally, measurements are performed to compare the superposed radiation patterns of the transmit and receive antennas with simulations.

Signal Detection Scheme Based on Adaptive Ensemble Deep Learning Model

Accurate signal detection is one of the most important requirements of wireless communication systems. The two most important processes of the signal detection are channel estimation and compensation. Since an orthogonal frequency-division multiplexing (OFDM) system among wireless communication systems uses orthogonal sub-carriers, the system has advantages of high bandwidth efficiency and simple channel compensation process compared with a single carrier system. However, due to the imperfect channel estimation and amplification of receiving noise by the channel compensation process, the reliability performance of the system is deteriorated according to the channel condition. This paper aims to introduce a new signal detection scheme based on deep learning. To address the challenges of signal detection, we propose the method which integrates the ensemble deep learning with the acquired received signals from multi-path channel according to the channel condition. The channel estimation corresponds to learning the deep neural network, and the channel compensation corresponds to assigning the received data to the learned network. Experiments on the OFDM symbol classification demonstrate that the proposed scheme has dramatically improved reliability performance compared with the conventional scheme.

PAPR reduction for FBMC/OQAM using hybrid scheme of different Precoding transform and mu-law companding

The filter banks multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is developing multicarrier modulation technique used in the next wireless communication system (5G). FBMC/OQAM supports high data rate and high band width efficiency. However, one of the major drawbacks of FBMC system is high peak to Average Power Ratio (PAPR) of the transmitted signal, which causes serious degradation in performance of the system. Therefore, it is required to use a proper PAPR scheme at the transmitter to reduce the PAPR. In this paper, a hybrid scheme is investigated with the combination of preceding transform technique and Mu Law Companding technique to reduce PAPR in FBMC systems. Moreover, four preceding techniques are examined to find the best Precoding technique which can be used with Mu law commanding. We assessed the discrete Hartley transform (DHT). The discrete cosine transformed (DCT), the Discrete Sine Transform (DST), and the Walsh Hadamard transforms (WHT) which are applied separately with Mu Companding. The numerical results verify that the FBMC systems with all Precoding technique combined with Mu law commanding can improve PAPR performance of the signals greatly with the best results achieved when the combination scheme consists of the DST Precoding and Mu law commanding for both PAPR and BER performance.

Performance of OFDM-FSO link with analog network coding

Free space optical (FSO) communication link based on orthogonal frequency division multiplexing (OFDM) gives improved performance because of high bandwidth efficiency, improved robustness against fading, and narrow-band interference. Any FSO system requires line-of-sight (LoS) link and in non-LoS (NLoS) situation, the two users cannot communicate directly resulting in link outage. To solve this problem, this paper proposes to use relay-assisted NLoS-FSO link with energy-saving three time-slotted analog network-coding approach to make the successful communication with increased throughput and improved error performance. The error performance of laser link is evaluated in terms of receiver sensitivity. Gamma–Gamma distribution is used for atmospheric turbulence in this analysis. The performance of relay-assisted intensity modulated/direct detected-OFDM FSO link with and without analog network coding (ANC) is compared.

High-efficiency wideband SiNx-on-SOI grating coupler with low fabrication complexity.

The chip-fiber grating coupler is a fundamental building block in integrated photonics, providing convenient on-wafer testing and packaging. Couplers based on a silicon nitride (SiNx) material platform can achieve wider bandwidths than silicon-based couplers, but suffer from lower efficiency due to the relative low material refractive index. The efficiency of the SiNx grating coupler can be improved by using high-reflectivity silicon grating reflectors underneath. However, such a silicon grating reflector requires several fabrication steps, including lithography, etching, high precision alignment (HPA), and chemical mechanical polishing (CMP). In this Letter, we demonstrate an easy-to-fabricate SiNx-on-SOI transverse-electric mode grating coupler requiring only one patterning step (grating alone), and without the need for HPA and CMP. A coupling coefficient of -2.5 dB and 1-dB-bandwidth of 65nm has been experimentally measured.