• Title, Summary, Keyword: directional radio transmission

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The Asymptotic Throughput and Connectivity of Cognitive Radio Networks with Directional Transmission

  • Wei, Zhiqing;Feng, Zhiyong;Zhang, Qixun;Li, Wei;Gulliver, T. Aaron
    • Journal of Communications and Networks
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    • v.16 no.2
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    • pp.227-237
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    • 2014
  • Throughput scaling laws for two coexisting ad hoc networks with m primary users (PUs) and n secondary users (SUs) randomly distributed in an unit area have been widely studied. Early work showed that the secondary network performs as well as stand-alone networks, namely, the per-node throughput of the secondary networks is ${\Theta}(1/\sqrt{n{\log}n})$. In this paper, we show that by exploiting directional spectrum opportunities in secondary network, the throughput of secondary network can be improved. If the beamwidth of secondary transmitter (TX)'s main lobe is ${\delta}=o(1/{\log}n)$, SUs can achieve a per-node throughput of ${\Theta}(1/\sqrt{n{\log}n})$ for directional transmission and omni reception (DTOR), which is ${\Theta}({\log}n)$ times higher than the throughput with-out directional transmission. On the contrary, if ${\delta}={\omega}(1/{\log}n)$, the throughput gain of SUs is $2{\pi}/{\delta}$ for DTOR compared with the throughput without directional antennas. Similarly, we have derived the throughput for other cases of directional transmission. The connectivity is another critical metric to evaluate the performance of random ad hoc networks. The relation between the number of SUs n and the number of PUs m is assumed to be $n=m^{\beta}$. We show that with the HDP-VDP routing scheme, which is widely employed in the analysis of throughput scaling laws of ad hoc networks, the connectivity of a single SU can be guaranteed when ${\beta}$ > 1, and the connectivity of a single secondary path can be guaranteed when ${\beta}$ > 2. While circumventing routing can improve the connectivity of cognitive radio ad hoc network, we verify that the connectivity of a single SU as well as a single secondary path can be guaranteed when ${\beta}$ > 1. Thus, to achieve the connectivity of secondary networks, the density of SUs should be (asymptotically) bigger than that of PUs.

Probability of exceeding the serviceability limit of antenna masts

  • Kammel, Christian
    • Wind and Structures
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    • v.4 no.4
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    • pp.353-366
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    • 2001
  • With respect to serviceability, antenna masts should be designed so that wind-induced motion will not cause unacceptable lack of transmission for broadcasting users and wireless communication. For such antenna masts with directional radio transmission the serviceability limit state is predominantly governed by the tolerable change of the broadcasting angle of the mounted antenna assembly and therefore by the tip distortion of the mast. In this paper it will be shown that refinements of the present state of design of antenna masts are possible by using the statistics of extremes applied to extreme wind situations and by consideration of the statistical and reliability requirements given by the operator such as frequency and return period of passing the serviceability limit.

On Power Allocation Schemes for Bi-directional Communication in a Spectrum Sharing-based Cognitive Radio System

  • Kim, Hyungjong;Wang, Hanho;Hong, Daesik
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.5
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    • pp.285-297
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    • 2014
  • This paper presents the results of an investigation into bi-directional communication in spectrum sharing-based cognitive radio (Bi-CR) systems. A Bi-CR system can increase the spectral efficiency significantly by sharing the spectrum and through the bi-directional use of spatial resources for two-way communication. On the other hand, the primary user experiences more interference from the secondary users in a Bi-CR system. Satisfying the interference constraint by simply reducing the transmission power results in performance degradation for secondary users. In addition, secondary users also experience self-interference from echo channels due to full duplexing. These imperfections may weaken the potential benefits of the Bi-CR system. Therefore, a new way to overcome these defects in the Bi-CR system is needed. To address this need, this paper proposes some novel power allocation schemes for the Bi-CR system. This contribution is based on two major analytic environments, i.e., noise-limited and interference-limited environments, for providing useful analysis. This paper first proposes an optimal power allocation (OPA) scheme in a noise-limited environment and then analyzes the achievable sum rates. This OPA scheme has an effect in the noise-limited environment. In addition, a power allocation scheme for the Bi-CR system in an interference-limited environment was also investigated. The numerical results showed that the proposed schemes can achieve the full duplexing gain available from the bi-directional use of spatial resources.

Spectrum Hole Utilization in Cognitive Two-way Relaying Networks

  • Gao, Yuan;Zhu, Changping;Tang, Yibin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.3
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    • pp.890-910
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    • 2014
  • This paper investigates the spectrum hole utilization of cooperative schemes for the two-way relaying model in order to improve the utilization efficiency of limited spectrum holes in cognitive radio networks with imperfect spectrum sensing. We propose two specific bidirectional secondary data transmission (BSDT) schemes with two-step and three-step two-way relaying models, i.e., two-BSDT and three-BSDT schemes, where the spectrum sensing and the secondary data transmission are jointly designed. In the proposed cooperative schemes, the best two-way relay channel between two secondary users is selected from a group of secondary users serving as cognitive relays and assists the bi-directional communication between the two secondary users without a direct link. The closed-form asymptotic expressions for outage probabilities of the two schemes are derived with a primary user protection constraint over Rayleigh fading channels. Based on the derived outage probabilities, the spectrum hole utilization is calculated to evaluate the percentage of spectrum holes used by the two secondary users for their successful information exchange without channel outage. Numerical results show that the spectrum hole utilization depends on the spectrum sensing overhead and the channel gain from a primary user to secondary users. Additionally, we compare the spectrum hole utilization of the two schemes as the varying of secondary signal to noise ratio, the number of cognitive relays, and symmetric and asymmetric channels.

Voice Communication Performance in 900MHz ISM Band Using Codec2 (Codec 2를 이용한 900MHz ISM대역에서의 음성 통신 성능 검토)

  • Kim, Gyeong-Jin;Kim, Jeong-Uk
    • Journal of the Korea Industrial Information Systems Research
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    • v.23 no.6
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    • pp.59-66
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    • 2018
  • In this paper, we experimented how long distance voice communication is possible After implemented PTT(Push to talk) Bi-directional radio using open source project Codec 2, which is a low speed voice codec for digital amateur radio and 900MHz FSK transceiver. In case of a general digital radio, the AMBE+2 codec, which is regarded as an industry standard in terms of performance, is expensive and has the monopoly of technology. Using the 400MHz band in terms of frequency, narrow bandwidth of DMR(12.5kHz) and DPMR(6.25kHz) is used, so the data rate is low. In the 900MHz bandwidth can be extended, which is advantageous in terms of data transmission. As a result of the voice quality and distance field test, we could find that the communication takes place within about 500m. In this paper, only voice communication is reviewed. if a review of data transmission such as a simple image is added, this solution can be used in various fields as a low cost IOT radio.

An adoption of the HFPD measuring system using directional coupler sensors to XLPE cable & accessories (방향성센서를 이용한 고주파 부분방전 측정시스템의 XLPE 케이블 및 접속함 적용)

  • Yu, In-Kee;Kim, Ki-Young;Jeong, Young-Woo
    • Proceedings of the KIEE Conference
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    • pp.1674-1676
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    • 2002
  • In this paper, High Frequency PD measuring system using directional coupler sensors(DCS) is introduced. Especially the principles of the DCS and characteristics of the system are introduced. Evaluation of this system was carried by an adoption to the test circuit of 345kV XLPE $2000mm^2$ cable and EB-A, EB-G, PIJ, PNJ. In the test a PD measurement was carried out without shieldroom and under the on-line state and in the high frequency range at the remote site from the test object. The test result was satisfactory and this is due to the use of DCS and using a high frequency range and specific filter for radio and TV signal and low pass. This system can be used to the test of a new construction of cable and accessories and measuring of long-term deterioration of cable and accessories. And this will bring us the reliability of a power transmission.

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Analysis of Impulse Dispersion for IR-UWB Antenna Using Time-Frequency Analysis (시간-주파수 분석을 이용한 IR-UWB 안테나 임펄스 분산 특성 분석)

  • Koh, Young-Mok;Ra, Keuk-Hwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.12
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    • pp.1371-1379
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    • 2010
  • This paper presents an analysis of impulse dispersion for impulse radio ultra-wide band(IR-UWB) antenna. A set of antenna structure configurations are highlighted with verification based on the STFT(Short Time Fourier Transform) in 3.1~5.1 GHz: first, a taper-slotted antenna allowing the optimal impulse transmission, and second, 4 types of the omni-directional IR-UWB antenna using different feed structures(microstrip line, and CPW(Coplanar Waveguide)). The proposed STFT allows the analysis of the IR-UWB antenna's dispersion characteristic.

Implementation of a portable telemetry system based on wavelet transform. (웨이블릿 알고리즘을 적용한 휴대용 텔레미트리 시스템)

  • 박차훈;서희돈
    • Proceedings of the IEEK Conference
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    • pp.113-116
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    • 2000
  • In this paper presents the portable wireless ECG data detection and diagnosis system based on discreet wavelet transform. An algorithm based on wavelet transform suitable for real time implementation has been developed in order to detect ECG characteristics. In particular, QRS complex, S and T waves may be distinguished form noise, baseline drift or artifacts. Proposed telemetry system that a transmitting media using radio frequency(RF) for the middle range measurement of the physiological signals and receiving media using optical for electromagnetic interference problem. A standard hi-directional serial communication interface between the telemetry system and a personal computer or laptop, allows read-time controlling, diagnosing and monitoring of system. A portable telemetry system within a size. of 65${\times}$125${\times}$45mm consists of three parts: a digital signal processing part for physiological signal detect or diagnose, RF transmitter for data transfer and a optical receiver for command receive. Advantages of proposed telemetry system is wireless middle range(50m) FM transmission, reduce electromagnetic interference to a minimum. which enables a comfortable diagnosis system at home.

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Analysis of Phase Velocity Matching in Coupled Microstrip Lines with Dielectric Overlay

  • Lee, Yong K.;Seung Y. Rhee;Kim, Nam;Park, Han K.
    • Journal of Electrical Engineering and information Science
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    • v.1 no.2
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    • pp.96-100
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    • 1996
  • This paper describes a concrete method for computing characteristic impedances and effective dielectric constants of the microstrip coupled lines without and with a dielectric overlay. The frequency-independent spectral domain method is used for the analysis of these lines. This method is a powerful, accurate, and numerically efficient approach for planar transmission line structure. For designing the optimal directional coupler, the velocities of even and odd mode must be equal but velocities of these two modes are different in the conventional coupled line which is inhomogeneous. The results show that these two velocities can be almost same according to variations of structural and material parameters in terms of the overlay(superstrate).

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Design of a Data Transmitter Modem using the DS/SS for the Active RF-ID system (능동형 RF-lD 시스템에 적용 가능한 DS/SS방식의 데이터 전송용 모뎀설계)

  • Park, Young-Hun;Kim, Jin-Kyung;Baek, Seung-Jae;Kwak, Jin-Kyu;Park, Jin-Soo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.1
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    • pp.539-542
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    • 2005
  • In this paper, we propose a wireless data access system, which used direct sequence spread spectrum method and the ISM band with 900MHz radio frequency. By applying bi-directional transmission between wireless transmitter and receiver, it can be effectively connected with any kinds of RF-ID with 900MHz ISM band. Therefore it could economically be used as peripheral equipments for RF-ID system.

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