Won-Jun Choi

Publications

2 An Improved STBC Structure and Transmission Scheme for High Rate and Reliability in OFDMA Cooperative Communication

Authors: Hyoung-Kyu Song, Won-Jun Choi, Hyoung-Muk Lim, Jae-Seon Yoon

Abstract:

Space-time block code(STBC) has been studied to get full diversity and full rate in multiple input multiple output(MIMO) system. Achieving full rate is difficult in cooperative communications due to the each user consumes the time slots for transmitting information in cooperation phase. So combining MIMO systems with cooperative communications has been researched for full diversity and full rate. In orthogonal frequency division multiple access (OFDMA) system, it is an alternative way that each user shares their allocated subchannels instead of using the MIMO system to improve the transmission rate. In this paper, a Decode-and-forward (DF) based cooperative communication scheme is proposed. The proposed scheme has improved transmission rate and reliability in multi-path fading channel of the OFDMA up-link condition by modified STBC structure and subchannel sharing.

Keywords: cooperation, OFDMA, STBC, improved rate

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1 A Novel Transmission Scheme for Reliable Cooperative Communication

Authors: Seung-Jun Yu, Hyoung-Kyu Song, Won-Jun Choi, Jung-In Baik

Abstract:

Cooperative communication scheme can be substituted for multiple-input multiple-output (MIMO) technique when it may not be able to support multiple antennas due to size, cost or hardware limitations. In other words, cooperative communication scheme is an efficient method to achieve spatial diversity without multiple antennas. For satisfaction of rising QoS, we propose a reliable cooperative communication scheme with M-QAM based Dual Carrier Modulation (M-DCM), which can increase diversity gain. Although our proposed scheme is very simple method, it gives us frequency and spatial diversity. Simulation result shows our proposed scheme obtains diversity gain more than the conventional cooperative communication scheme.

Keywords: Diversity, cooperation, OFDM, M-DCM

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