共查询到20条相似文献,搜索用时 15 毫秒
1.
Tsuyoshi Ogino Naoki Ohashi Shunichi HishitaIsao Sakaguchi Yutaka AdachiKunihiko Nakajima Hajime Haneda 《Thin solid films》2012,520(10):3835-3838
The high frequency characteristics of hybrid structures made from indium tin oxide (ITO) films and very fine gold (Au) lines were theoretically and experimentally investigated to develop invisible coplanar waveguide (CPW) structures for microwave and millimeter-wave applications. After optimizing the Au/ITO hybrid structures, we achieved fabrication of an invisible CPW structure showing both high transmission and low reflection characteristics in the GHz range. Electromagnetic simulations by using a finite elements method explained the reason for the improved characteristics of the optimized Au/ITO hybrid CPW. 相似文献
2.
We optimize the design of a short-range communication system using nondirected line-of-sight IR radiation. We propose a receiver structure comprising a spherical thin-film optical filter and a truncated spherical lens that can significantly outperform an optimized planar-filter system. We can make the passband of the spherical filter arbitrarily narrow without constraining the field of view by using an arbitrarily large filter radius. We argue that a truncation angle of 90° maximizes the receiver field of view when a spherical filter is used. We jointly optimize the transmitter radiation pattern and receiver optical components. Numerical results show that 269 mW of transmitted signal power is sufficient to achieve 100 Mbit/s throughout a 4-m-radius cell with high background irradiance. 相似文献
3.
Hadjinicolaou M.G. Nilavalan R. Itagaki T. Voskarides S.C. Pattichis C.S. Schizas A.N. 《Communications, IET》2009,3(8):1284-1296
For the first time, a complete wireless and mobile emergency TeleOrthoPaedics system with field trials and expert opinion is presented. The system enables doctors in a remote area to obtain a second opinion from doctors in the hospital using secured wireless telecommunication networks. Doctors can exchange securely medical images and video as well as other important data, and thus perform remote consultations, fast and accurately using a user friendly interface, via a reliable and secure telemedicine system of low cost. The quality of the transmitted compressed (JPEG2000) images was measured using different metrics and doctors opinions. The results have shown that all metrics were within acceptable limits. The performance of the system was evaluated successfully under different wireless communication links based on real data. 相似文献
4.
Guo Liang Goh Jiaheng Ma Kwee Lim Francis Chua Agarwala Shweta Yue Ping Zhang 《Virtual and Physical Prototyping》2016,11(4):289-294
This research focuses on exploring low-cost and rapid production solutions for fabricating emitters for patch antennas for wireless communication applications. Additive manufacturing technique is employed to fabricate two patch antennas using silver nanoparticle ink on FR4 substrate. Finite-element simulation software, HFSS is used to analyse and predict the theoretical performance of the antenna designs for 2.4?GHz MIMO and 6?GHz wireless data transmission. The fabricated antennas have resonant frequencies closely matching the design values. The work provides a viable solution for fabricating emitters and finally antennas commercially using inkjet printing platform, thus overall reducing the cost and simplifying the process. 相似文献
5.
An effective design of a reconfigurable patch antenna, with a wide operational bandwidth for wireless communication and radar systems, is presented in this paper. The reconfigurable patch possesses an E-shaped structure and its operation frequency can be changed by integrated switches. The operational frequency of the antenna can cover an octave frequency range by utilising only two switch states. In state 1, the antenna operates from 9.2 GHz to 15.0 GHz and, in state 2, from 7.5 GHz to 10.7 GHz. Relative bandwidths of 48% and 35% are obtained in the two states, respectively 相似文献
6.
Multispot diffuse configuration (MSDC) for indoor wireless optical communications, utilizing multibeam transmitter and angle diversity detection, is one of the most promising ways of achieving high capacities for use in high-bandwidth islands such as classrooms, hotel lobbies, shopping malls, and train stations. Typically, the optical front end of the receiver consists of an optical concentrator to increase the received optical signal power and an optical bandpass filter to reject the ambient light. Using the unique properties of holographic optical elements (HOE), we propose a novel design for the receiver optical subsystem used in MSDC. With a holographic curved mirror as an optical front end, the receiver would achieve more than an 10-dB improvement in the electrical signal-to-noise ratio compared with a bare photodetector. Features such as multifunctionality of the HOE and the receiver's small size, light weight, and low cost make the receiver front end a promising candidate for a user's portable equipment in broadband indoor wireless multimedia access. 相似文献
7.
DC-OFDM超宽带无线通信系统 总被引:1,自引:0,他引:1
对高速超宽带(UWB)无线通信技术进行了研究,提出了双载波-正交频分复用(DC-OFDM)UWB系统方案,包括频带划分方案、帧结构和发射端系统方案以及参考接收机方案,给出了方案的计算机仿真结果和硬件实验结果.DC-OFDM UWB方案采用独创的双载波结构,降低了对射频和基带关键电路硬件实现的要求,获得了频域分集效果,提高了频谱使用灵活性.硬件实验系统的无线传输速率达到110 Mbps,传输距离为10m,信号发射功率小于0.1mW. 相似文献
8.
Over the last few years, developments in wireless communications have presented many challenges to the antenna and microwave communities in terms of special requirements for antenna design, fabrication and integration. These requirements include new characterisation in terms of antenna performance, miniaturised size and shape and new suitable fabrication and implementation techniques to fit with the devices. These aspects are addressed with a focus on recent developments in dielectric resonator antenna research to meet some of the new challenges. A few recent representative designs, which outline new innovations and improved antenna features, as well as directions for future research, are briefly described. 相似文献
9.
Kipens G Leib H Saw J Nisbet J Dai JD 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1998,45(3):634-649
Commutation signaling is a bandwidth expanding modulation scheme that is robust to multipath induced intersymbol interference making it suitable for wireless digital communications. By using multipath diversity combining, commutation signaling exploits the time diversity that is inherent in a multipath propagation environment. This paper considers a surface acoustic wave (SAW) implementation of a commutation signaling modem for broadband indoor wireless communication. The modem employs differential encoding and a form of direct sequence spread spectrum modulation with the following specifications: data rate 40 Mb/sec, chip rate 200 MHz, and IF frequency 1 GHz. The differential coherent detector is a key element of a low cost, low complexity commutation signaling modem. A commutation signaling differential coherent detector has been implemented using SAW and RF integrated circuit (RF IC) technologies. The SAW devices have been fabricated on 1280-rotated Y-cut, X-propagating lithium niobate using approximately 1 micron line widths. RF IC technology Is used to implement the high-speed bilinear multipliers needed for differential coherent detection as well as the low-impedance buffers used to drive these multipliers. 相似文献
10.
Adickes Martin D. Billo Richard E. Norman Bryan A. Banerjee Sujata Nnaji Bartholomew O. Rajgopal Jayant 《IIE Transactions》2002,34(9):823-836
Radio Frequency Data Communications (RFDC)technology is rapidly becoming a critical component of many traditional industrial engineering functions including materials tracking, inventory control, warehousing, order processing, shipping and database management. As a means of moving information, RFDC has many attractive features, such as speed, accuracy, reliability, convenience and low operating costs. When implementing RFDC systems a major problem is to quickly and efficiently determine the locations where transceivers should be placed so that effective radio communication can take place. The research described in this paper addresses this issue by developing a computerized layout simulation system that incorporates heuristic optimization methods to solve the placement problem. The effectiveness of this unique automated layout methodology is demonstrated by comparing it with the current method of utilizing manual site surveys, as well as with other placement methods. The methodology and solutions are validated by field-testing at actual facilities. 相似文献
11.
There is an increasing demand for transdermal high-data-rate communication for use with in-body devices, such as pacemakers, smart prostheses, neural signals processors at the brain interface, and cameras acting as artificial eyes as well as for collecting signals generated within the human body. Prominent requirements of these communication systems include (1) wireless modality, (2) noise immunity and (3) ultra-low-power consumption for the in-body device. Today, the common wireless methods for transdermal communication are based on communication at radio frequencies, electrical induction, or acoustic waves. In this paper, we will explore another alternative to these methods--optical wireless communication (OWC)--for which modulated light carries the information. The main advantages of OWC in transdermal communication, by comparison to the other methods, are the high data rates and immunity to external interference availed, which combine to make it a promising technology for next-generation systems. In this paper, we present a mathematical model and experimental results of measurements from direct link and retroreflection link configurations with Gallus gallus domesticus derma as the transdermal channel. The main conclusion from this work is that an OWC link is an attractive communication solution in medical applications. For a modulating retroreflective link to become a competitive solution in comparison with a direct link, low-energy-consumption modulating retroreflectors should be developed. 相似文献
12.
《IEEE transactions on instrumentation and measurement》2003,52(4):1097-1106
Repeatability problems, usually accompanied by low accuracy, are often experienced in power measurements, especially in those concerning spread spectrum signals, peculiar to digital wireless communication systems, and involving a specified frequency range. For this concern, a new method for power measurements is presented. The method applies original and straightforward digital signal-processing algorithms to the input signal power spectrum, preliminarily provided by optimized versions of well-known estimators, such as those based on weighted overlapped segment averaging and multitaper approaches. The outcomes of many experiments, conducted on spread spectrum signals of third-generation telecommunication systems, confirm the efficacy of the proposed method in assuring reliable and accurate results in various types of power measurement. 相似文献
13.
Performance of optical wireless communication (OWC) systems can be optimised using constant optical power transmission in conjunction with forward error control coding. A new family of constant power error correcting codes using multiple pulse position modulation optical transmission are introduced. This doubly featured technique may extend the capability of many difficult wireless optical links beyond their existing barriers and may enable a higher error performance for OWC networks. The potential and design of look-up table codes are investigated. The Monte Carlo methods provide supportive data for the performance and code word search. 相似文献
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15.
X Liu 《Applied optics》2012,51(19):4463-4468
It has been important to optimize the transmitter power in wireless optical communication systems. The conventional approach was based on the reciprocal Pareto model. In this paper, the investigation is extended to a more general scenario where the instantaneous signal-to-noise ratio follows the log-square-Ricean distribution. Accordingly, the optimization model is established. The conventional model thus becomes a special case of the new model. It is shown that the new model can be analytically solved. The sample solutions clearly show how the optima of transmitter power change when the log-square-Ricean profile changes. These results would provide useful guidelines to system design. 相似文献
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17.
The diffuse radiance outgoing from mirror-attenuator-mosaic diffusers is with in certain limits independent from the angle of the incident light. Such diffusers are useful as calibration sources for the Scanner for Radiation Budget radiometer and for similar purposes as well. Two techniques of production of directional diffusers (etching and diamond drilling) are compared. To measure the performance of the samples, a new measurement setup is introduced that permits the direct comparison of incoming and outgoing light with an accuracy of better than 0.5%. The diamond drilling technique shows a much better performance than the etching. 相似文献
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19.
Peer-to-peer (P2P) communications have attracted a great deal of attention from the network research community in recent years. However, due to the fundamental limitations of wireless environments, providing reliable data availability for P2P applications over wireless ad hoc networks is still a major challenge. To address the problem, a distributed and randomised scheme based on self-avoiding walks is proposed. The scheme concatenates disparate network layers, with the goal of recovering from routing failures that disrupt P2P data accessibility. In addition, a probabilistic approach is presented that explores the tradeoffs between several system parameters. Some new analysis tools, such as path coupling, are utilised which provide a better understanding of the system's operations. That the proposed concepts and techniques make a significant contribution to the design of effective and efficient P2P applications in wireless ad hoc networks is believed. 相似文献
20.
In this paper, a simple design of a complementary filter is presented for performance measurement of an IS-95 code division multiple access wireless communication system (1995). The complementary filter is required to meet the design requirements, which are specified in IS-97 document (1994). The purpose of employing the complementary filter in test equipment is to remove intersymbol interference introduced by the base station transmit-filter and the transmit-phase equalizer. Five window functions, which do not affect the desirable response at the proper sampling times, are applied to the desirable output. The output of a window Is set to be the output of the complementary filter. Then, the complementary filter is obtained by taking a deconvolution of the output response of the window with the impulse response resulted by cascading the base station transmit-filter and the transmit-equalizer. It is found that the output of the complementary filter with the Kaiser window function meets all requirements specified in IS-97. In addition, it is observed that the Kaiser window has the smallest number of the filter coefficients among all windows considered in this paper. Therefore, the complementary filter with the Kaiser window is recommended for implementation of the IS-95 system measurement 相似文献