Kyusung Shim

Outage performance of physical layer security for multi-hop underlay cognitive radio networks with imperfect channel state information

In this paper, we consider a multi-hop decode-and-forward (DF) relaying transmission in underlay cognitive radio networks. Considering the presence of an eavesdropper that overhears the transmission, we address secure communications of multi-hop wireless communications in terms of physical layer security. In addition, we take in to account the effect of imperfect channel state information (CSI) which is of importance issue in underlay cognitive radio. We analyze the secrecy outage performance of the system over Rayleigh fading channels. In particular, we derive the closed-form expression of the system secrecy outage probability. The analysis results are validated by the Monte-Carlo simulation results. The numerical results show that the imperfect CSI issue does not effect on the security issue of the transmission in underlay cognitive radio networks. On the other hand, the number of hops plays a key role in the physical layer security.

LED Communication-based PC-PC Transmission System

LED is just a semiconductor which can produce light. Currently, there are active research works on LED lighting technologies according to the growth of energy-saving environmental industry. Especially, LED communication is one of the active research works in these fields. In this paper, we design a LED communication-based PC-PC transmission system. A transmission circuit system(transmitter) using LED and a receiving circuit system(receiver) using PD(photo detector) and Op-amp are designed, respectively. The experiments for the designed system are performed as follows. One computer is connected at the end of transmitter and receiver, respectively, and text files are transmitted by using text transmission programming. In this experiment, we test the performance with various baud rates, LED colors, transmission ranges.

Exploiting Opportunistic Scheduling for Physical-Layer Security in Multitwo User NOMA Networks

In this paper, we address the opportunistic scheduling in multitwo user NOMA system consisting of one base station, multinear user, multifar user, and one eavesdropper. To improve the secrecy performance, we propose the users selection scheme, called best-secure-near-user best-secure-far-user (BSNBSF) scheme. The BSNBSF scheme aims to select the best near-far user pair, whose data transmission is the most robust against the overhearing of an eavesdropper. In order to facilitate the performance analysis of the BSNBSF scheme in terms of secrecy outage performance, we derive the exact closed-form expression for secrecy outage probability (SOP) of the selected near user and the tight approximated closed-form expression for SOP of the selected far user, respectively. Additionally, we propose the descent-based search method to find the optimal values of the power allocation coefficients that can minimize the total secrecy outage probability (TSOP). The developed analyses are corroborated through Monte Carlo simulation. Comparisons with the random-near-user random-far-user (RNRF) scheme are performed and show that the proposed scheme significantly improves the secrecy performance.

Multi-to-One Visible Lighting Communication based IoT System using Rolling Shutter Technique

본 논문에서 롤링셔터기법을 이용한 Multi-to-One 가시광통신 기반 IoT 시스템을 제안한다. 제안된 시스템의 특징 및 기여도는 다음과 같다. 첫째, 송신부는 Multi-to-One 가시광통신을 통하여 다수의 센서노드들이 주변 환경을 측정하여 LED를 이용하여 하나의 수신부로 데이터를 전송한다. 둘째, 수신부는 다수의 송신 LED 통신을 이용하여 전송된 디지털 데이터 신호를 스마트폰카메라를 이용하여 수신 받고 이미지 프로세싱 과정을 통하여 수신효율을 높인 후 각각의 데이터베이스에 저장한다. 셋째, 제안하는 시스템은 저장된 데이터베이스를 사용자들이 쉽게 확인할 수 있도록 웹 서버에서 시각화 하여 그래프의 형태로 데이터를 제공한다. 성능 평가를 통하여 본 논문에서 제안하는 시스템은 다수의 송신부 LED 통신을 이용하여 전송된 디지털 신호를 수신부에서 동시에 저장하고 시각화 가능하여 제공하며, 측정된 데이터를 효과적인 속도로 전송이 가능함을 보여준다.

Performance Analysis of Physical Layer Security of Opportunistic Scheduling in Multiuser Multirelay Cooperative Networks

In this paper, we study the physical layer security (PLS) of opportunistic scheduling for uplink scenarios of multiuser multirelay cooperative networks. To this end, we propose a low-complexity, yet comparable secrecy performance source relay selection scheme, called the proposed source relay selection (PSRS) scheme. Specifically, the PSRS scheme first selects the least vulnerable source and then selects the relay that maximizes the system secrecy capacity for the given selected source. Additionally, the maximal ratio combining (MRC) technique and the selection combining (SC) technique are considered at the eavesdropper, respectively. Investigating the system performance in terms of secrecy outage probability (SOP), closed-form expressions of the SOP are derived. The developed analysis is corroborated through Monte Carlo simulation. Numerical results show that the PSRS scheme significantly improves the secure ability of the system compared to that of the random source relay selection scheme, but does not outperform the optimal joint source relay selection (OJSRS) scheme. However, the PSRS scheme drastically reduces the required amount of channel state information (CSI) estimations compared to that required by the OJSRS scheme, specially in dense cooperative networks.