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On Maximum Diversity Order over Doubly-Selective MIMO-OFDM Channes
Yang Qinghai,Kwak Kyung Sup The Korea Institute of Information and Commucation 2005 韓國通信學會論文誌 Vol.30 No.7a
The analysis of maximum diversity order and coding gain for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems over time-and frequency-selective (or doubly-selective) channels is addressed in this paper. A novel channel time-space correlation function is developed given the spatially correlated doubly-selective Rayleigh fading channel model. Based on this channel-model assumption, the upper-bound of pairwise error probability (PEP) for MIMO-OFDM systems is derived under the maximum likelihood (ML) detection. For a certain space-frequency code, we quantify the maximum diversity order and deduce the expression of coding gain. In this wort the impact of channel time selectivity is especially studied and a new definition of time diversity is illustrated correspondingly
Symbol Error Rate of Cooperative Transmission Using OSTBC
YANG, Qinghai,ZHONG, Yingji,KWAK, Kyung Sup The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.1
<P>We investigate the symbol error rate (SER) of the cooperative transmission with the decode-and-forward relay protocol under Rayleigh fading channels. The technique of orthogonal space-time block coding (OSTBC) is applied at the links source-relay, source-destination and relay-destination. A closed-form SER expression is derived. Simulation results demonstrate the theoretical solutions.</P>
Sub-Optimum Training Design for Spatially Correlated Doubly-Selective MIMO-OFDM Channels
Qinghai Yang,Shaoyi Xu,Kyung Sup Kwak 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
We design a sub-optimal training scheme for MIMO-OFDM systems under spatially correlated time- and frequency- (doubly) selective fading channels. We first develop the optimal pilot symbols and placement of pilot clusters with respect to the minimum mean square error (MMSE) of the linear channel estimate. We then derive the sub-optimal power allocation for pilot symbols in a twowater- level way: By maximizing the averaged capacity lower bound, how much power to be allocated to training is determined subject to the global water level (or the constraint of total transmit power); Subsequently, pouring power to the pilot symbols with an approximately optimal water filling scheme subject to the local water level (or the constraint of assigned power for training). In addition, for a particular OFDM size, the optimal number of pilot clusters is derived by maximizing the capacity lower bound and by minimizing the channel estimate's MMSE.