• Title, Summary, Keyword: ultra-wideband (UWB)

Search Result 381, Processing Time 0.035 seconds

Impulse Series for UWB-Based Cognitive Radio System

  • Zhang, Weihua;Shen, Hanbing;Bai, Zhiquan;Kwak, Kyung-Sup
    • ETRI Journal
    • /
    • v.29 no.4
    • /
    • pp.518-520
    • /
    • 2007
  • In this letter, we propose an impulse series for an ultra-wideband-based cognitive radio system which can utilize the spectrum dynamically by controlling the impulse positions and thus reduce the system complexity.

  • PDF

Development of Ultra-Wideband Antennas

  • Chen, Zhi Ning
    • Journal of electromagnetic engineering and science
    • /
    • v.13 no.2
    • /
    • pp.63-72
    • /
    • 2013
  • The ultra-wideband (UWB) spectrum available for commercial applications has offered us an opportunity to achieve high-speed wireless communications and high-accuracy location applications. As one of key research areas in UWB technology, a lot of innovative broadband and miniaturization techniques for UWB antennas have been greatly invented and developed for years. This paper reviews the development of UWB antenna design in the past decade. Starting with a brief introduction of the specific requirements and promising applications of UWB systems, the unique design challenges of UWB antennas are highlighted. Next, the important milestones of UWB antenna designs are briefed. After that, a variety of planar UWB antennas invented for broadband operation, miniaturization, and multiple functions are introduced. Last, the comments on the development of UWB antennas in future are shared.

Designing Optimal Pulse-Shapers for Ultra-Wideband Radios

  • Luo, Xiliang;Yang , Liuqing;Giannakis, Georgios-B.
    • Journal of Communications and Networks
    • /
    • v.5 no.4
    • /
    • pp.344-353
    • /
    • 2003
  • Ultra-wideband (UWB) technology is gaining increasing interest for its potential application to short-range indoor wireless communications. Utilizing ultra-short pulses, UWB baseband transmissions enable rich multipath diversity, and can be demodulated with low complexity receivers. Compliance with the FCC spectral mask, and interference avoidance to, and from, co-existing narrow-band services, calls for judicious design of UWB pulse shapers. This paper introduces pulse shaper designs for UWB radios, which optimally utilize the bandwidth and power allowed by the FCC spectral mask. The resulting baseband UWB systems can be either single-band, or, multi-band. More important, the novel pulse shapers can support dynamic avoidance of narrow-band interference, as well as efficient implementation of fast frequency hopping, without invoking analog carriers.

On the Ultra-Wideband Ambiguity Function (초광대역 Ambiguity Function에 관한 연구)

  • 이준용
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.29 no.3C
    • /
    • pp.368-373
    • /
    • 2004
  • Extremely fine tine resolution of ultra-wideband (UWB) signal poses a new problems to the system designer. A reasonable accuracy of the system clock is necessary to process signals with such a high space resolution. A useful way of illustrating the time resolution of a signal is to evaluate the ambiguity function. The ambiguity function for carrierless UWB defined using the time mismatch and time scaling factor as its two parameters. The UWB ambiguity function is evaluated for various signaling schemes of impulse radio.

Cognitive UWB-OFDM: Pushing Ultra-Wideband Beyond Its Limit via Opportunistic Spectrum Usage

  • Arslan Huseyin;Sahin Mustafa E.
    • Journal of Communications and Networks
    • /
    • v.8 no.2
    • /
    • pp.151-157
    • /
    • 2006
  • In a continuously expanding wireless world, the number of radio systems increases every day and efficient spectrum usage becomes a more significant requirement. Ultra-wideband (UWB) and cognitive radio are two exciting technologies that offer new approaches to the spectrum usage. The main objective of this paper is to shed the first light on the marriage of these two important approaches. The strength of orthogonal frequency division multiplexing (OFDM) based UWB in co-existing with licensed systems is investigated. The opportunity concept is defined, and the requirements of the opportunistic spectrum usage are explained. It is proposed to take the UWB-OFDM from the current underlay implementation, and evolve it to a combined underlay and opportunistic spectrum usage technology, leading to cognitive UWB-OFDM. This way, we aim at making UWB more competitive in the wireless market with extended range, higher capacity, better performance, and a wide variety of applications.

초광대역(Ultra wideband : UWB) 기술과 고해상도 레이더

  • 박영진;김관호;윤동기
    • Information and Communications Magazine
    • /
    • v.20 no.2
    • /
    • pp.109-117
    • /
    • 2003
  • UWB 기술은 주파수 영역에서 광대역을 갖는 임펄스를 사용하므로 목표물로부터 많은 정보를 얻어, 고해상도 레이더 개발이 가능하다. 이러한 UWB 레이더의 특성을 이용하여 한국전기연구원에서는 지중 금속 물체를 탐지하기 위한 지반 탐사 레이더를 개발하였다. 개발된 레이더는 실제환경에서 금속 물체를 탐지하기 위해서 시험되었다. 개발된 레이더는 물체의 깊이에 대해 고해상도를 가졌고, 동작 파장보다 훨씬 작은 금속 물체까지도 탐지가 가능함을 보였다. 본 논문에서는 개발된 지반 탐사 UWB 레이더 시스템을 소개하고, UWB 레이더의 특성 및 UWB 기술에 대해 기술하고자 한다.

Interference Avoidance Technology Using Cognitive UWB in Ultra Wideband Systems (Cognitive UWB 기술을 이용한 UWB 시스템에서의 간섭 회피 기술)

  • Hwang, Jae-Ho;Sohn, Sung-Hwan;Lee, Sung-Jun;Kim, Jae-Moung
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.32 no.8A
    • /
    • pp.836-846
    • /
    • 2007
  • Wireless Communication is playing a key role in implementing the ubiquitous society. However, due to the increasing wireless and mobile devices occupying the spectrum, the frequency resources are believed to become more and more limited. In order to deal with the problem, coexistence is considered to be a effective method to improve the efficiency of spectrum utilization between several different systems. Here, we utilize the UWB system to realize the coexistence, because it is an ultra wide band system which can co-exist with other narrow band systems. On the other hand, Cognitive Radio technology is an intelligent technology which can sense the spectrum environment and adaptively adjust the parameters for wireless transmission. In this paper, by using Cognitive UWB, the spectrum efficiency of the transmission channels is largely improved; Furthermore, the interference to other systems can be effectively avoided.

The Interference Measurement Analysis between 3.412 GHz Band Broadcasting System and UWB Wireless Communication System

  • Song Hong-Jong;Kim Dong-Ku
    • Journal of electromagnetic engineering and science
    • /
    • v.6 no.1
    • /
    • pp.76-81
    • /
    • 2006
  • Ultra wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as Broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a orthogonal frequency division Multiplex UWB source and an impulse radio UWB source, to a Broadcasting transmission system. The receive power degradations of broadcasting system are presented. From these experimental results, we show that in all practical cases UWB system can coexist 35 m distance in-band broadcasting network.

Band-Notched Ultra-Wideband Antenna with Asymmetric Coupled-Line for WLAN and X-Band Military Satellite

  • Lee, Jun-Hyuk;Sung, Young-Je
    • Journal of electromagnetic engineering and science
    • /
    • v.13 no.1
    • /
    • pp.34-37
    • /
    • 2013
  • This paper presents a novel ultra-wideband (UWB) antenna that rejects narrow and broad bands and is suitable for wireless communications. The base of the proposed antenna has a circular patch that can cover the UWB frequency range (3.1~10.6 GHz). The interference issues caused by co-existence within the UWB operation frequency are overcome by a design that uses a parallel-coupled asymmetric dual-line with a circular monopole antenna. The proposed antenna showed a stable radiation pattern, realized gain and reflection coefficient lower than -10 dB across the UWB operation bandwidth except for 5.15~5.85 GHz and 7.25~8.4 GHz. The fabrication, simulation, and measurement results obtained for the proposed antenna were in good agreement with the expected values.

Improvement of Ultra-wideband Link Performance over Bands Requiring Interference Mitigation in Korea

  • Rateb, Ahmad M.;Syed-Yusof, Syarifah Kamilah;Fisal, Norsheila
    • ETRI Journal
    • /
    • v.32 no.1
    • /
    • pp.44-52
    • /
    • 2010
  • Ultra-wideband (UWB) systems have witnessed a debate over whether they may cause interference to other existing and future narrowband systems sharing their band of operation. The detect and avoid (DAA) mechanism was developed as a solution to reduce interference to narrowband systems in order to ease regulatory concerns. It works by adaptively reducing the transmitted power at the overlapping bands upon detecting an active narrowband link. However, employing DAA degrades the performance of UWB transmissions. In this paper, we present the Korean UWB regulations as an example of regulations that require DAA in certain bands. We investigate DAA's impact on performance and propose a method to mitigate it, which provides UWB with the more efficient support of the DAA mechanism and enables it to avoid a larger number of narrowband users while sustaining the data rate. Results show significant improvement in performance with the application of our technique compared to conventional performance.