• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2003.11a
• /
• pp.171-174
• /
• 2003

본 논문은 기존의 표준 8-VSB 방식의 DTV 수신 성능 개선을 위해 ATSC T3/S9에 제안되었던 기술 중에서 현재 새로운 표준안으로 채택이 유력시되는 Zenith/ATI의 Enhanced 8-VSB 방식과 Philips의 Pseudo 2-VSB 방식에 대해 살펴보고, 다양한 채널 환경에 대해서 전산 모의 실험을 실시하여 자 방식의 수신 성능을 비친, 분석하였다. 이중 스트림 기술을 사용하였을 때, 강인한 트렐리스 부호화를 거친 강인데이터의 성능 개선 정도와 강인데이터가 표준데이터에 미치는 성능 개선 정도를 SNR에 따른 트렐리스 디코더의 바이트 에러율을 통해서 비교, 분석하였다.

• Journal of Satellite, Information and Communications
• /
• v.5 no.1
• /
• pp.90-93
• /
• 2010

This paper shows various perfermance analysis utilizing STC(Space Time Coding) in MIMO mobile communication by WiBro system environments. In this paper, 3 algorithm which are SM method, ML (Maximum Likelihood) and ZF(Zero Forcing) algorithm use for perfermance analysis. From the various simulation result, it is confirm that ZF method is superior compare than STC and ML method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.7 no.3
• /
• pp.201-210
• /
• 1996

In this paper, we analyzed performance of a symbol timing recovery scheme for 16QAM Radio system. As a symbol timing recovery scheme, both maximum amplitude method(MAM) and wave difference method(WDM) are analyzed employing a pulse shaping filter, such as raised cosine filter(RCF) and nonlinear filter(NLF). Simulation result shows that the jitter performance of MAM or WDM using NLF is better than that using square root RCF. In order to estimate and compensate for the Rayleigh fading PSAM(Pilot Symbol Assisted Modulation) and space diversity are also employed. Consequently, BER performance of about $10^{-4}$ is obtained for $E_b/N_o$= 20 dB.

• The KIPS Transactions:PartC
• /
• v.14C no.5
• /
• pp.417-424
• /
• 2007

Mesh networks using WLAN technology have been paid attention as a key wireless access technology. However, many technical issues still exist for its successful deployment. One of those issues is the routing problem that addresses the path setup through a WLAN mesh network for the data exchanges between a station and a wired network. Since the characteristics of a WLAN mesh network can be very dynamic, the use of single routing protocol would not fit for all environments whether it is reactive or proactive. Therefore, it is required to develop an adaptive routing protocol that modifies itself according to the changes in the network parameters. As a logical first step for the development, an analytical model considering all the dynamic features of a WLAN mesh network is required to evaluate the performance of a reactive and a proactive routing scheme. In this paper, we propose an analytical model that makes us scrutinize the impact of the network and station parameters on the performance of each routing protocol. Our model includes the size of a mesh network, the density of stations, mobility of stations. and the duration of network topology change. We applied our model to the AODV that is a representative reactive routing protocol and DSDV that is a representative proactive routing protocol to analyze the tradeoff between AODV and DSDV in dynamic network environments. Our model is expected to help developing an adaptive routing protocol for a WLAN mesh network.

• Journal of Broadcast Engineering
• /
• v.19 no.6
• /
• pp.826-835
• /
• 2014

Recently, spatial modulation (SM) schemes are considered to improve the reception performance in spatially correlated channel environments. SM schemes utilize a switching method between multiple transmitters to reduce the correlation among multiple transmitters to reduce the correlation of each received signals and can support transmission additional bits using antenna combinations without extra bandwidth. Therefore, SM schemes can overcome correlation interference of conventional MIMO in urban wireless channels. However, the performance comparisons between SM schemes are not yet performed in correlated urban wireless channels. In this paper, some representative SM schemes are compared and a suitable SM-MIMO system in correlated urban wireless channels is proposed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.7
• /
• pp.572-580
• /
• 2013

IEEE 802.15.4e is a prospective standard for low latency control application in industries. This paper proposes a framework to evaluate the closed loop IEEE 802.15.4e based WNCS performance. The framework consists of two models: closed loop control system model and network model. The network model focuses on the PHY parameters of wireless link and takes the channel parameters into consideration. The PHY model combining with MAC model gives the control system model the probability of packet loss in a super-frame. In addition, redundancy mechanism is considered in IEEE 802.15.4e to reduce to data frame loss probability. The simulation is implemented in Matlab, PHY model takes the channel parameters from empirical results. Hence our evaluation gives insight into behavior of WNCS in different environments and it provides us a tool to design wireless network to achieve a good performance for control system.

• Journal of IKEEE
• /
• v.25 no.3
• /
• pp.420-424
• /
• 2021

The massive MIMO system, which is a core technology of 5G communication systems, has a problem that it is difficult to implement in a frequency division duplex system based on limited channel feedback because a large amount of channel information is required at the transmitting end. In order to solve this problem, the Joint Spatial Division and Multiplexing (JSDM) technique that dramatically reduces the channel information requirement by removing interference between the user groups using channel correlation information that does not change for a long time has been proposed. Recently, a regularized JSDM technique has been proposed to further improve performance by allowing residual interference between the user groups. However, such JSDM-related studies were mainly designed to focus on inter-group interference cancellation, and thus performance analysis was not performed in a more realistic environment assuming limited feedback in the intra-group interference cancellation phase. In this paper, we analyze the performance of the JSDM and regularized JSDM techniques according to the number of groups and users in a limited feedback environment, and through the simulation results, demonstrate that the regularized JSDM technique shows a more remarkable advantage compared to the existing JSDM in a limited feedback environments.

• Smart Media Journal
• /
• v.10 no.2
• /
• pp.92-99
• /
• 2021

Smart space is a technology that supports humans by interacting with the surrounding environment. Smart space has a built-in dynamic intelligent environment. This paper proposes a framework that provides user-customized dynamic intelligent environments in smart spaces. In the existing research that provides user-customized intelligent services, users' interests are only explicitly analyzed, and smart spaces are not considered. Implicit interest analysis can suggest a service that may be of interest to users rather than explicit interest analysis, but it requires higher performance than explicit interest analysis. Smart spaces can obtain useful information by interacting with information in the space. The framework proposed in the study uses a proximity-based social network of things to fit into a smart space. In addition, the implicit interest analysis provides intelligent information for smart spaces using the social media information and spatial information objects. In addition, we propose a method to prevent performance degradation while maintaining accuracy in consideration of the characteristics of the smart space.

• Journal of KIISE:Information Networking
• /
• v.28 no.1
• /
• pp.82-92
• /
• 2001

데이터 방송은 무선 통신 환경에서 많은 사용자들에게 정보를 전달하는데 있어 효과적인 방안으로 주목받고 있다. 데이터 방송 시스템에서의 중요문제 중 하나는 사용자 기다림을 최소화하는 것이다. 사용자 대기시간을 줄이는 데는 두 가지 접근법이 있다. 하나는 대기시간을 최소화하는 방송 스케쥴의설계이고 다른 하나는 사용자 시스템이 지역 메모리를 캐쉬로 이용하여 사용자 요구에 즉각 응답하는 것이다. 이두 가지 접근법은 동시에 적용되어 전체 성능을 보다 좋게 할 수 있다. 효율적인 방송시스템의 설계 및 구현을 위해서는 방송 스케쥴, 캐쉬 크기, 캐슁 정책등 여러 가지 요인을 종합적으로 고려하는 것이 필요하다. 본 놈누에서는 WWW과 같이 정보 항목들간에 구조적 연관 관계가 존재하는 시스템에서 앞서 기술한 여러 가지 요인을 함께 고려하여 방송 시스템의 성능을 분석하였다. 분석적 기법을 이용하여 채택한 방송 스케쥴 캐슁 정책의 조합으로 얻을수 있는 시스템 성능의 하한을 구하였다. 이 결과를 이용하면 여러 가지 시스템 구현 방안간의 성능 비교가 가능하며 이를 통해 효과적인 방송 시스템의 설계 및 구현이 가능할 것이다. 우리는 분석의 타당성 검증을 위해 시뮬레이션을 수행하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.5
• /
• pp.19-25
• /
• 2009

In this paper, the constellation rearrangement method for retransmission based on Chase combining, is introduced. And the effectiveness of the recommended constellation rearrangements is analyzed with statistics. Their performance for turbo-coded or convolutional coded bit streams is evaluated with simulation under additive white Gaussian noise environment.