Code-Division Multiplexing based Hardware Reduction for a Digital Beamforming Transmitter Array

This paper proposes a new system architecture to reduce the hardware cost for a digital beamforming (DBF) transmitter array. In a conventional DBF transmitter array, each signal channel requires a digitalto-analog converter (DAC) to convert the digital signal to the analog signal, so that the cost and power consumption for such systems are often prohibitively high as the array size increases. In the proposed DBF transmitter array system, code-division multiplexing (CDM) technique is used to combine digital signals from different channels, and thus the required number of DACs can be significantly reduced. The combined signal is separated by demodulation with the corresponding code sequences for each channel after the DAC. Principle of CDM for hardware reduction in a DBF array system is analyzed. A system-level simulation is performed in Simulink to verify the performance of the proposed system. Simulation results show that the beamforming accuracy and signal quality can be maintained with a reduced number of DACs. European Conference on Antennas and Propagation (EuCAP) This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Research Laboratories, Inc.; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Research Laboratories, Inc. All rights reserved. Copyright c © Mitsubishi Electric Research Laboratories, Inc., 2018 201 Broadway, Cambridge, Massachusetts 02139 Code-Division Multiplexing based Hardware Reduction for a Digital Beamforming Transmitter Array Zhengyu Peng1,3, Kyeong Jin Kim1, Pu Wang1, Rui Ma1, Kazunari Kihira2, Toru Fukasawa2, Changzhi Li3, Bingnan Wang1,* 1Mitsubishi Electric Research Laboratories (MERL), Cambridge, MA, USA *bwang@merl.com 2Information Technology R&D Center, Mitsubishi Electric Corporation, 5-1-1 Ofuna, Kamakura-shi, Japan 3Dept. of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX, USA Abstract—This paper proposes a new system architecture to reduce the hardware cost for a digital beamforming (DBF) transmitter array. In a conventional DBF transmitter array, each signal channel requires a digitalto-analog converter (DAC) to convert the digital signal to the analog signal, so that the cost and power consumption for such systems are often prohibitively high as the array size increases. In the proposed DBF transmitter array system, code-division multiplexing (CDM) technique is used to combine digital signals from different channels, and thus the required number of DACs can be significantly reduced. The combined signal is separated by demodulation with the corresponding code sequences for each channel after the DAC. Principle of CDM for hardware reduction in a DBF array system is analyzed. A system-level simulation is performed in Simulink to verify the performance of the proposed system. Simulation results show that the beamforming accuracy and signal quality can be maintained with a reduced number of DACs.