An Investigation of Wideband Rectennas for Wireless Energy Harvesting

This paper is focused on a wireless energy harvesting system using a rectifying antenna (rectenna). The proposed device consists of a wideband cross-dipole antenna, a microwave low-pass filter and a doubling rectifying circuit using Shottcky diodes as rectifying elements. Previously, a few of wideband rectennas have been investigated at 1.7 to 2.5 GHz. The originality of this paper is on the new wideband rectenna design which can harvest the ambient radio frequency (RF) power at 1.7 to 2.5 GHz. In this system, a new wideband cross dipole is designed and used to achieve the required bandwidth and duel-polarization. In addition, the voltage doubling rectifying circuit is optimized to achieve the best performance at power density levels 2 which are typical in urban environments. The characteristics of the proposed rectenna over the desired frequency range are investigated, and the integrated rectenna is simulated, made and tested for low input power densities from 5 to 200 μW/cm2. The simulation and measurement results of the rectenna are compared and a good agreement is achieved. The results demonstrate that the maximum rectenna conversion efficiency is nearly 57% around 1.7 GHz and over 20% over the wideband of interest for the incident power density of 120 μW/cm2. It is noted that the impedance matching is one of the main factors affecting the rectenna energy conversion efficiency. This new wideband rectenna has great potential to harvest wireless energy in GSM/3G/4G and ISM 2.4 GHz bands.

Reviews and Reflections of the Development of Broadband Wireless Mobile Communications in the US

Accompanying the increasing growth of marketneeds is the extremely fast progress of technologiesin the wireless communications sector; as Chinaadopts a major special project plan for the implementationof a new generation of broadband wirelessmobile communications networks at the end of2007, existing mobile communication networkswill evolve to broadband wireless mobile communicationnetworks and substitute traditional fixedline broadband access methods. With the US beingone of the countries of the fastest growth of broadbandwireless mobile communication technologies,this article attempts to draw on regulatory policies,business development, standard selection, andmarket applications, etc. of the US to offer suggestionsfor broadband wireless mobile communicationdevelopment to China.

Research on OFDM & Broadband Wireless

Recently, wireless communication industry has made gigantic progress, and the related re-searches and applications are very active.

ZTE's Broadband Wireless Access System

1 IntroductionWith the rapid development of backbonenetworks,the subscriber accessnetwork,a major component of publictelecom network equipment and so-called the“last kilometer”,has turned out to bethe focus of attention.Among various access technologies,thebroadband wireless access system featuresquick network construction,rapid investmentreturn and large bandwidth.It enables newnetwork operators to provide services quickly

Research and Development of New Broadband Wireless Access System

Broadband Wireless Access (BWA) has become one of the major evolution trends in the fields of broadband access and mobile communications. However,some difficulties emerged during the application and industrialization of the BWA system,which calls for typical service models,key technology innovations and backbone support from broadband Internet. This article introduces a Broadband Wireless Multimedia (BWM) access system. It aims to build a new-type "triple play" BWA network by integrating terrestrial digital TV system and the BWA system,and by taking broadband Internet as its core network platform. A primary research shows that the new BWA system is an effective solution to the existing difficulties of BWA system. Moreover,it is quite competitive in service provision,service coverage,frequency planning,terminal power consumption and cost for network construction.

New Blue Ocean of Wideband Wireless Mobile Internet: Modern Service

Wideband Wireless Mobile Internet (WWMI) has become one of the most important technologies for Modern Service. The Modern Service information communication multi-access network can easily realize the new operation modes formed by various Modern Service support systems. We think that under the new operation modes, the charges on calling and information will become more negligible, while the charge on services provided by the direct service support of various Modern Service platforms will turn into a major revenue source. It is suggested that the operators build an operation service support platform with common services to cooperate with thousands of information websites, help clients to transform information into profit and carry out operations and services.

Thinking About Developing 3G and Broadband Wireless Access Technologies

It is wise for fixed operators to make use of broadband wireless access technologies,such as IEEE802.16d,to develop mobile access based on their existing fixed broadband IP networks.Mobile operators have to evolve their networks from 2G to 3G for making full use of their current resources. However,the AII-IP core network will be a general trend since broadband wireless access adopts the connectionless statistical packet multiplexing technology.Based on the introduction of IEEE802.16d,High Speed Downlink Packet Access (HSDPA) and CDMA2000 1x EV-DV technologies,this paper discusses the development trend of broadband wireless access technologies, and concludes that 3G's packet access technologies are the same as IEEE802.16d/e,and AII-IP is the goal.It emphasizes that Chinese TD-SCDMA should develop toward connectionless statistical packet multiplexing as early as possible.

MODIFIED ULTRA WIDEBAND CIRCULAR PRINTED MONOPOLE ANTENNA

A simple and compact microstrip-fed ultra wideband （UWB） printed monopole antenna is presented. The antenna is composed of a circular radiator and a finitely grounded plane. The antenna occupies about 16.62 GHz absolute bandwidth and 142.7% relative bandwidth covering from 3.38 GHz to 20 GHz with voltage standing wave ratio （VSWR） below two. A quasi-omnidirectional and quasi-symmetrical radiation pattern in H plane is obtained in the whole bandwidth. The high performance of the antenna is validated with measured and simulated results given. The antenna can be applied for the system design of UWB wireless communication.

Ultra-wideband RCS reduction using novel configured chessboard metasurface

A novel artificial magnetic conductor（AMC） metasurface is proposed with ultra-wideband 180？phase difference for radar cross section（RCS） reduction. It is composed of two dual-resonant AMC cells, which enable a broadband phase difference of 180°±30°from 7.9 GHz to 19.2 GHz to be achieved. A novel strategy is devised by dividing each rectangular grid in a chessboard configuration into four triangular grids, leading to a further reduction of peak bistatic RCS. Both fullwave simulation and measurement results show that the proposed metasurface presents a good RCS reduction property over an ultra-wideband frequency range.

AN ADAPTIVE MEASUREMENT SCHEME BASED ON COMPRESSED SENSING FOR WIDEBAND SPECTRUM DETECTION IN COGNITIVE WSN

An Adaptive Measurement Scheme (AMS) is investigated with Compressed Sensing (CS) theory in Cognitive Wireless Sensor Network (C-WSN). Local sensing information is collected via energy detection with Analog-to-Information Converter (AIC) at massive cognitive sensors, and sparse representation is considered with the exploration of spatial temporal correlation structure of detected signals. Adaptive measurement matrix is designed in AMS, which is based on maximum energy subset selection. Energy subset is calculated with sparse transformation of sensing information, and maximum energy subset is selected as the row vector of adaptive measurement matrix. In addition, the measurement matrix is constructed by orthogonalization of those selected row vectors, which also satisfies the Restricted Isometry Property (RIP) in CS theory. Orthogonal Matching Pursuit (OMP) reconstruction algorithm is implemented at sink node to recover original information. Simulation results are performed with the comparison of Random Measurement Scheme (RMS). It is revealed that, signal reconstruction effect based on AMS is superior to conventional RMS Gaussian measurement. Moreover, AMS has better detection performance than RMS at lower compression rate region, and it is suitable for large-scale C-WSN wideband spectrum sensing.

Broadband beam steering for misaligned multi-mode OAM communication systems

Orbital angular momentum(OAM)at radio frequency(RF)has attracted more and more attention as a novel approach of multiplexing a set of orthogonal OAM modes on the same frequency channel to achieve high spectral efficiency(SE).However,the precondition for maintaining the orthogonality among different OAM modes is perfect alignment of the transmit and receive uniform circular arrays(UCAs),which is difficult to be satisfied in practical wireless communication scenarios.Therefore,to achieve available multi-mode OAM broadband wireless communication,we first investigate the effect of oblique angles on the transmission performance of the multi-mode OAM broadband system in the non-parallel misalignment case.Then,we compare the UCA-based RF analog and baseband digital transceiver structures and corresponding beam steering schemes.Mathematical analysis and numerical simulations validate that the SE of the misaligned multi-mode OAM broadband system is quite low,while analog and digital beam steering(DBS)both can significantly improve the SE of the system.However,DBS can obtain higher SE than analog beam steering especially when the bandwidth and the number of array elements are large,which validates that the baseband digital transceiver with DBS is more suitable for multi-mode OAM broadband wireless communication systems in practice.

A Novel Broadband Antenna Design for 5G Applications

Wireless communication is one of the rapidly-growing elds of the communication industry.This continuous growth motivates the antenna community to design new radiating structures to meet the needs of the market.The 5G wireless communication has received a lot of attention from both academia and industry and signicant efforts have been made to improve different aspects,such as data rate,latency,mobility,reliability and QoS.Antenna design has received renewed attention in the last decade due to its potential applications in 5G,IoT,mmWave,and massive MIMO.This paper proposes a novel design of broadband antenna for 5G mmWave and optical communication networks.It is a hybrid structure that works for both spectrums and contains an absorption dielectric material with an electrical large size.A hybrid transmission line theory ray-tracing technique is proposed efcient and rapid simulation and optimization of the proposed antenna design.The operating frequency and wavelength of the proposed antenna are 28 GHz in the mmWave band and 1550 nm for the optical spectrum.The spatial frequency is 30 lp/mm when the contrast transfer function is reduced to 0.7 for the optical signal.The effective focal length and aperture are 816.86 and 200 mm.The half-power beamwidth is 3.29◦and the gain is 32.97 dBi for the mmWave band.Simulation results show that the proposed hybrid antenna can effectively be deployed simultaneously for both optical and mmWave 5G communication networks.

Complex Domain Wavelet-Based Denoising of Measured UHF Wireless Channel Power Delay Profiles

This work extends the use of wavelet-based denoising as an alternative processing scheme to improve measured mobile-radio channel power delay profiles. It has already been reported that, when applied on real domain data (amplitude only), denoising provides mainly a qualitative improvement. Here, phase content was also considered, leading to significant qualitative and quantitative improvement of the processed profiles. Signal-to-noise ratios and dynamic ranges improvements as high as 50 dB have been observed.

Experimental Study of On-Body Radio Channel Performance of a Compact Ultra Wideband Antenna

In this paper, on-body radio channel performance of a compact ultra wideband (UWB) antenna is investigated for body-centric wireless communications. Measurement campaigns were first done in the chamber and then repeated in an indoor environment for comparison. The path loss parameter for eight different on-body radio channels has been characterized and analyzed. In addition, the path loss was modeled as a function of distance for 34 different receiver locations for propagation along the front part of the body. Results and analysis show that, compared with anechoic chamber, a reduction of 16.34% path loss exponent is noticed in indoor environment. The antenna shows very good on-body radio channel performance and will be a suitable candidate for future efficient and reliable body-centric wireless communications.

A NOVEL ULTRA WIDEBAND MONOPOLE ANTENNA WITH BAND-NOTCHED CHARACTERISTICS

A simple and compact microstrip-fed Ultra WideBand(UWB) printed monopole antenna with band-notched characteristic is proposed in this paper.The antenna is composed of a square ring with a small strip bar,so that the antenna occupies about 7.69 GHz bandwidth covering 3.11～10.8 GHz with expected band rejection from 5.12 GHz to 5.87 GHz.A quasi-omnidirectional and quasi-sym-metrical radiation pattern is also obtained.This kind of band-notched UWB antenna requires no ex-ternal filters and thus greatly simplifies the system design of UWB wireless communication.

A Self-Similar Fractal Cantor Antenna for MICS Band Wireless Applications

Low profile antenna in communication is a new methodology. Fractal geometry is a methodology through which size reduction is achieved. A Self-similar fractal antenna using multicantor technique is proposed and experimentally studied. Space-filling cantors and self-similarity properties of fractal geometry have been adopted in the proposed antenna to miniaturize the size of antenna. The antenna is designed in such a way to operate at MICS band (Medical Implant communication Service) for wireless telemedicine application. The prototype antenna exhibits wideband characteristics and provides a good agreement of return loss (S11). Experimental return loss has been compared with that which is obtained using method of moments. The objective of using self-similar concept in antenna makes it flexible in terms of controlling the resonance and bandwidth. In this paper, the Self-similar property of fractal geometry is examined by maintaining return loss (S11) more than –30 dB approximately in all the iterations (n) and the prototype antenna has return loss greater than –10 dB and exhibits wideband characteristics.

Wireless Communication Networks' Planning in Underdeveloped Countries

The planning of wireless communication networks in underdeveloped countries is studied for landline telephone, fixed broadband wireless access and PLMN systems via investigation and discussion of the LDC networks＇ characteristic, technology selection, deployment consideration, network configuring, civil work evaluation and investment estimation. An example is embedded all through providing a general

无线超宽带通信技术星载应用研究

采用无线通信实现电气互连可以有效缓解星上电缆布局难、维护难、更改难等问题。相比窄带连续波无线通信,超宽带通信技术具有功率谱密度低、信号分辨率高、频谱共存能力强、信道容量大、复杂度低等特点,具有较好的应用前景。欧洲Eu:CROPIS卫星、日本ETS-9卫星、国际空间站哥伦布实验舱等已经开展了无线超宽带通信的应用研究和演示验证。针对星上高可靠、低时延、可扩展无线组网需求,分析了多跳分簇网络拓扑、无线信号传输模型、无线传输电磁干扰模型、高精度时间同步、灵活组网与可靠传输等关键技术和解决途径,形成适用于星上无线传输的通信技术体制和解决方案,为卫星少缆化、无缆化通信奠定技术基础。