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A Scheme of Joint Beam-Forming and Transmit Diversity for Closed-Loop Downlink Transmission |
Xu Hong-ji; Liu lu |
School of Info. Sci. and Eng., Shandong University, Jinan 250100, China |
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Abstract Multi-antenna technique is an effective means of improving performance of the downlink transmission. Both Beam-Forming (BF) and Transmit Diversity (TD) which exploit multiple antennas are attractive candidates for improving the system performance and increasing the channel capacity. In this paper, an adaptive downlink transmission scheme combining BF with TD in the closed-loop mode is proposed. And it includes two methods, one uses the diversity antenna array and is suitable for the slowly time-varying channel, and the other uses the BF antenna array and is suitable for fast time-varying channel. The transmitter can adaptively change the transmission mode between two methods according to the actual channel states. The algorithm of the adaptive scheme is investigated in the paper, and the complexity of the algorithm and its applicable environment are also analyzed. The simulation results show that the new scheme can achieve both BF gains and TD gains; while it improves the performance of the Bit Error Rate (BER), it can enhance the adaptive ability to the channel variance of the wireless system.
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Received: 09 February 2004
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