• Title/Summary/Keyword: D2D Communications

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Sector-Based Device Discovery Scheme for D2D Communication in LTE-Advanced Networks (LTE-Advanced 네트워크에서 D2D 통신을 위한 섹터 기반 디바이스 디스커버리 기술)

  • Kim, Hyang-mi;Lee, Han-na;Kim, Sangkyung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.8
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    • pp.1521-1531
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    • 2015
  • According to the service attributes, D2D communications establish 1-1, or 1-n channels and require the differentiated device discovery technology. This paper proposes a sector-based device discovery mechanism for 1-n D2D communication scenario in LTE-Advanced networks that a disaster happened. Our proposal is a mechanism that can extend the coverage in a disaster situation which a number of devices(survivors) need to be discovered in a short time. In the single cell environment, a larger discovery coverage can be obtained, and in the multi-cell, it is possible to mitigate the interference with adjacent links due to sector-based coverage control. Through a set of simulations, we have confirmed that our proposal has better performance in the number of devices discovered and the interference than the legacy broadcast device discover mechanism.

Interference Mitigation Scheme for Device-to-Device MIMO Communications Underlaying a Cellular Network

  • Nam, Yujin;So, Jaewoo;Kim, Jinsung
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.4
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    • pp.1841-1865
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    • 2017
  • This paper proposes a new interference mitigation scheme for device-to-device (D2D) communications underlaying a cellular network. The object of the proposed scheme is to determine the number of data streams, a precoding matrix, and a decoding matrix of D2D networks so as to maximize the system capacity given the number of data streams of a cellular network while satisfying the constraint of the inter-system interference from D2D networks to the cellular network. Unlike existing interference mitigation schemes based on the interference alignment technique, the proposed scheme operates properly regardless of the number of data streams of a cellular network and moreover it does not require changing the precoding and decoding matrices of a cellular network. The simulation results demonstrate that the proposed scheme significantly increases the system capacity by mitigating the intra- and inter-system interference.

Design and Implementation of a Broadband Power Divider (광대역전력분배기의 설계 및 제작)

  • Kang, Sanggee
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.9
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    • pp.560-562
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    • 2014
  • Broadband power divider operating over the frequency band assigned for all domestic mobile communications is designed and implemented. The implemented power divider with 20Watts power rating has the maximum insertion loss of 3.49dB, input reflection coefficient of below -18.48dB and output reflection coefficient of below -20.2dB, above 24.7dB isolation and -141.2dBc of 3rd PIMD over the operating frequency of 810 ~ 2620MHz.

Rotationally Invariant Space-Time Trellis Codes with 4-D Rectangular Constellations for High Data Rate Wireless Communications

  • Sterian, Corneliu Eugen D.;Wang, Cheng-Xiang;Johnsen, Ragnar;Patzold, Matthias
    • Journal of Communications and Networks
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    • v.6 no.3
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    • pp.258-268
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    • 2004
  • We demonstrate rotationally invariant space-time (ST) trellis codes with a 4-D rectangular signal constellation for data transmission over fading channels using two transmit antennas. The rotational invariance is a good property to have that may alleviate the task of the carrier phase tracking circuit in the receiver. The transmitted data stream is segmented into eight bit blocks and quadrature amplitude modulated using a 256 point 4-D signal constellation whose 2-D constituent constellation is a 16 point square constellation doubly partitioned. The 4-D signal constellation is simply the Cartesian product of the 2-D signal constellation with it-self and has 32 subsets. The partition is performed on one side into four subsets A, B, C, and D with increased minimum-squared Euclidian distance, and on the other side into four rings, where each ring includes four points of equal energy. We propose both linear and nonlinear ST trellis codes and perform simulations using an appropriate multiple-input multiple-output (MIMO) channel model. The 4-D ST codes constructed here demonstrate about the same frame error rate (FER) performance as their 2-D counterparts, having however the added value of rotational invariance.

Ku-Band Transitions between Microstrip and Substrate Integrated Waveguide and Microstrip and Hollow Substrate Integrated Waveguide (Ku-대역 마이크로스트립-SIW 및 마이크로스트립-HSIW 천이 구조)

  • Hong, Sung-June;Kim, Seil;Lee, Min-Pyo;Lim, Jun-Su;Kim, Dong-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.30 no.2
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    • pp.95-103
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    • 2019
  • In this paper, we present a microstrip-to-substrate integrated waveguide(SIW) transition and microstrip-to-hollow SIW(HSIW) transition for Ku-band satellite communication systems. For the complete utilization of the HSIW, a structure filled with air instead of a dielectric material, a microstrip-to-HSIW transition is designed, fabricated, and compared with a microstrip-to-SIW transition. A back-to-back microstrip-to-SIW transition is measured in the range 12~18 GHz; it exhibits a return loss ${\geq}20dB$ and an insertion loss of $1.5{\pm}0.2dB$. In contrast, a back-to-back microstrip-to-HSIW transition exhibits a return loss of at least 15 dB and an insertion loss of $0.55{\pm}0.2dB$ in the same frequency range.

D2D Utility Maximization in the Cellular System: Distributed Algorithm (셀룰라시스템에서 D2D 효용 극대화: 분산적 알고리즘)

  • Oh, Changyoon
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2019.01a
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    • pp.89-90
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    • 2019
  • 본 논문에서는 D2D 단말이 셀룰라 시스템의 상향링크 자원을 재사용하는 환경에서 D2D 단말들의 효용함수 극대화 방안을 제안한다. 기존 셀룰라 단말의 간섭영향을 고려하여 기지국 수신단 총 간섭량을 제한하고, D2D 송신단 전송전력량을 제한한다. D2D 단말들의 효용 극대화를 위해서는 모든 링크간의 채널 정보를 요구하므로, 부분적인 링크 채널 정보만을 필요로 하는 분산적 알고리즘을 제안하도록 한다.

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Disk Sector Antenna fed by CPW for UWB Communications (UWB 통신용 CPW 급전 디스크 섹터 안테나)

  • Lim, Jung-Hyun;Lee, Min-Soo;Yang, Doo-Yeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.2
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    • pp.303-312
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    • 2009
  • In this paper, we design and fabricate a disk sector antenna fed by CPW fur UWB communications. Also, we insert a rectangular slit on the arc-edge of the disk sector antenna. Then, the antenna has the directivity of E-면. In order to design the antenna, the input impedance is matched with the feed line of $50{\Omega}$ as varying the physical antenna parameters, which are the radius, the flare angle of disk sector, the length of ground, and the length of ground comer near by feed tine. Dimension of the antenna designed for UWB communication is $72mm{\times}26mm$ and bandwidth through computer simulation is $3{\sim}13GHz$. From the measured results, the bandwidth is $1.98{\sim}11GHz$. Return loss and gain of the fabricated antenna are -50.38dB, 1.34dBi at 3.5GHz, -12.27dB, 3.35dBi at 5.5GHz, -23.2dB, 3.8dBi at 8GHz and -16.17dB, 5.2dBi at 10GHz, respectively.

A Simple $\textit{d}_2$ Factor ($d_2^s$) for Control Charts

  • Lee, Jea-Young;Lee, Jae-Woo
    • Communications for Statistical Applications and Methods
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    • v.6 no.1
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    • pp.69-76
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    • 1999
  • A new statistic {{{{ {d }`_{2 } ^{s } }}}} is introduced for constructing co ntrol limits. It is easier and more convienient than d2 We will show the characteristic of {{{{ {d }`_{2 } ^{s } }}}} and evaluate {{{{ {d }`_{2 } ^{s } }}}} through average run length(ARL).

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Secure Transmission Scheme Based on the Artificial Noise in D2D-Enabled Full-Duplex Cellular Networks

  • Chen, Yajun;Yi, Ming;Zhong, Zhou;Ma, Keming;Huang, Kaizhi;Ji, Xinsheng
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.10
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    • pp.4923-4939
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    • 2019
  • In this paper, a secure transmission scheme based on the artificial noise is proposed for D2D communications underlaying the full-duplex cellular network, and a secure power allocation scheme to maximize the overall secrecy rate of both the cellular user and D2D transmitter node is presented. Firstly, the full-duplex base station transmits the artificial noise to guarantee the secure communications when it receives signals of cellular uplinks. Under this secure framework, it is found that improving the transmission power of the cellular user or the D2D transmitter node will degrade the secrecy rate of the other, although will improve itself secrecy rate obviously. Hence, a secure power allocation scheme to maximize the overall secrecy rate is presented subject to the security requirement of the cellular user. However, the original power optimization problem is non-convex. To efficiently solve it, we recast the original problem into a convex program problem by utilizing the proper relaxation and the successive convex approximation algorithm. Simulation results evaluate the effectiveness of the proposed scheme.