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왕우붕,장경희,Wang, Yu-Peng,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2008 韓國通信學會論文誌 Vol.33 No.3A
In this paper, we analyze the M-WiMAX UL capacity limits under 2-Tier cell layout, considering the effects of random user position, path loss models, fading channel and adjacent channel interference from WCDMA system. In order to make the analysis approximate to the practical system capacity, we propose a MCS-based capacity analysis method considering the effects of PER requirement and the utilized MCS levels in M-WiMAX system. The proposed MCS-based method is validated through a system-level Monte Carlo simulation. Furthermore, a comparison between the conventional Shannon method and the proposed MCS-based method is presented and the optimum cell radius is suggested.
왕우붕,고상준,장경희,Wang, Yu-Peng,Ko, Sang-Jun,Chang, Kyung-Hi The Korean Institute of Communications and Informa 2007 韓國通信學會論文誌 Vol.32 No.6a
This paper presents the coexistence issues between M-WiMAX TDD and WCDMA FDD systems. To improve the M-WiMAX system performance and to reduce the adjacent channel interference to WCDMA FDD system, transmit and receive beamforming techniques are applied in the base stations of M-WiMAX system. Furthermore, we propose an adjacent channel interference modeling methodology, which captures the effect of transmit beamforming on the adjacent channel interference. Besides, we verify the performance improvement in the uplink of WCDMA system due to the transmit beamforming in M-WiMAX downlink based on the proposed adjacent channel interference modeling methodology. We also verify the performance enhancement due to the receive beamforming in the uplink of M-WiMAX system through system level Monte Carlo simulations, considering random user position, the effect of shadowing and multi-path fading channel. Discussions on the gain of applying transmit and receive beamforming in M-WiMAX system comparing the case of SISO system are also included. Furthermore, we present the performance of cosited M-WiMAX and WCDMA systems, considering commercial deployment, additional channel filter at base stations and the effects of TxBF and RxBF.
Double-Dwell Hybrid Acquisition in DS-UWB System
왕우붕,장경희,Wang YuPeng,Chang Kyung-Hi The Korea Institute of Information and Commucation 2006 韓國通信學會論文誌 Vol.31 No.7a
In this paper, we analyze the performance of double-dwell hybrid initial acquisition in DS-UWB system via detection, miss, false alarm probabilities and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence, and deployment scenario of the abundant multipath components over the small coverage of the piconet in DS-UWB system. Based on the simulation, we obtain various performance on the mean acquisition time by varying the parameters, such as the total number of hypotheses to be searched, subgroup size, and dwell time. Then, we suggest the optimum parameter set for the initial acquisition in DS-UWB system.
YuPeng Wang(왕우붕),KyungHi Chang(장경희) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.3A
In this paper, we analyze the M-WiMAX UL capacity limits under 2-Tier cell layout, considering the effects of random user position, path loss models, fading channel and adjacent channel interference from WCDMA system. In order to make the analysis approximate to the practical system capacity, we propose a MCS-based capacity analysis method considering the effects of PER requirement and the utilized MCS levels in M-WiMAX system. The proposed MCS-based method is validated through a system-level Monte Carlo simulation. Furthermore, a comparison between the conventional Shannon method and the proposed MCS-based method is presented and the optimum cell radius is suggested.
UWB MB-OFDM 시스템을 위한 심볼 타이밍 및 반송파 주파수 오프셋 추정 기법
김정주,왕우붕,장경희,Kim Jung-Ju,Wang Yu-Peng,Chang Kyung-Hi 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.3A
본 논문에서는 Wireless PAN(WPAN)을 위하여 IEEE 802.15.3a의 표준안으로 제안된 Ultra WideBand(UWB) Multi-Band OFDM(MB-OFDM) 시스템에서의 프리앰블 모델을 분석하교, 효율적이며 향상된 성능을 제공하는 심볼 타이밍 및 반송파 주파수 오프셋 추정 알고리즘을 적용한 후 AWGN 및 UWB 채널 환경에서 모의 실험을 통하여 심볼 타이밍 오프셋 추정 성능은 Detection Probability, False Alarm Probability, Missing Probability 및 Mean Acquisition Time으로, 반송파 주파수 오프셋 추정 성능은 MSE(Mean Square Error)로 확인한다. In this paper, we analyze the preamble model for Wireless PAN(WPAN) in proposed Ultra WideBand(UWB) Multi-Band OFDM(MB-OFDM) system of IEEE 802.15.3a standard. Besides, we propose effective Carrier Frequency Offset and Symbol Timing Offset Estimation algorithm which offers enhanced performance, and analyze its performance using Detection Probability, False Alarm Probability, Missing Probability, Mean Acquisition Time and MSE(Mean Square Error) through simulation in AWGN and UWB channel environments.
2.6 GHz 대역에서 M-WiMAX OFDMA/TDD 시스템과 WCDMA FDD 시스템간의 상호 간섭 분석 Part I : SISO 시스템에서의 상호 간섭 분석
고상준,왕우붕,장경희,Ko, Sang-Jun,Wang, Yu-Peng,Chang, Kyung-Hi 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.6a
본 논문에서는 2.6 GHz 대역에서 WCDMA (Wideband Code Division Multiple Access) 시스템과 M-WiMAX (Mobile-Worldwide Interoperability for Microwave Access) 시스템 모두 SISO (Single Input Single Output) 만을 적용한 상태에서, 상호 시스템 간에 미치는 간섭의 영향을 분석한다. 간섭이 발생하는 경우는 각 시스템 별로 네 가지로써, 총 여덟 가지의 경우가 존재한다. 그 중에서도 간섭원의 하향링크가 피간섭원의 상향링크에 미치는 간섭의 크기가 가장 심각한 경우임을 밝히며, 간섭의 영향을 최소화하기 위해 여덟 가지 경우 모두에 5MHz 의 보호대역을 적용한다. 특히 M-WiMAX 시스템이 피간섭원인 경우가 WCDMA 시스템이 피간섭원인 경우에 비해 더 많은 간섭이 발생하며, 이는 두 시스템간의 최대 송신 전력의 차이가 주된 원인으로 작용한다. 본 논문에서는 실질적인 상황과는 다르게 Spectrum Mask 내에 간섭원에 해당되는 시스템의 송신전력이 가득 채워져 있는 경우로 가정하였기 때문에, 보다 엄격한 Emission Mask를 사용하고 실질적인 시스템 간 간섭분석의 Worst-case 결과로 볼 수 있다. In this paper, we analyze the adjacent interference between WCDMA and M-WiMAX systems in the 2.6GHz Band under the SISO (Single Input Single Output) configuration. The interference scenarios are characterized into 8 scenarios with different victim and interfering links. Among the 8 scenarios, we find that the most performance loss is observed in the scenarios of victim uplink suffering interference from downlink in both systems. Besides, guard band is applied to mitigate the adjacent interference in all the scenarios. Especially, we reveal that M-WiMAX system is much more sensitive to adjacent interference than WCDMA system due to the lower transmission power. In this paper, we consider the worst interference environment, where interferers always transmit with the maximum power, a loose spectrum mask is adapted, and no additional channel fitters are equipped in both systems.
IEEE 802.16e OFDMA TDD 시스템 하향링크 트래픽 채널의 Fixed-point 구현 방법론
김규현,선태형,왕우붕,장경희,박형일,어익수,Kim Kyoo-Hyun,Sun Tae-Hyung,Wang Yu-Peng,Chang Kyung-Hi,Park Hyung-Il,Eo Ik-Soo 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.6A
본 논문에서는 IEEE 802.16e에 기반한 OFDMA TDD 시스템 하향 링크 트래픽 채널의 fixed-point 구현을 위해 Floating-point 모델로부터 성능 열화와 하드웨어 복잡도를 최소화 할 수 있도록 적절한 비트 사이즈를 결정하는 방법론에 대하여 기술한다. Fixed-point 구현에 있어서 여러 가지 고려 사항 중 하나는 비트 사이즈를 절사하는 방법에 따른 Saturation과 Quantization의 선택이며, 반드시 주의해야 할 점은 신호의 분포를 정확히 파악한 후 신호의 분포에 맞도록 Saturation과 Quantization 중 하나의 비트 절사방법을 적절히 적용시켜야 한다는 점이다. 또한, 시행착오를 거치면서 여러 비트 사이즈에 대하여 모의 실험을 수행하여야만 성능 열화를 최소화 하면서 원하는 비트 사이즈를 얻을 수 있다. 본 논문에서는 수신단의 트래픽 채널에 최적화된 비트 사이즈를 결정하기 위하여 AWGN 및 ITU-R M.1225의 Veh-A 채널 환경에서 컴퓨터 모의 실험을 수행한다. This paper propose to methodology for deciding suitable bit size that minimizes hardware complexity and performance degradation from floating-point design the fixed-point implementation of downlink traffic channel of IEEE 802.16e OFDMA TDD system. One of the major considering issues for implementing fixed-point design is to select Saturation or Quantization properly with the knowledge of signal distribution by pdf or histogram. Also, through trial and error, we should execute exhaustive computer simulation for various bit sizes, hence obtain appropriate bit size while minimizing performance degradation. We carry out computer simulation to decide the optimized bit size of downlink traffic channel under AWGN and ITU-R M.1225 Veh-A channel model.