中国邮电高校学报(英文) ›› 2018, Vol. 25 ›› Issue (5): 31-38.doi: 10.19682/j.cnki.1005-8885.2018.0031

• Wireless • 上一篇    下一篇

Hybrid beamforming with discrete phase shifters for millimeter wave backhaul networks

袁江伟1,李晓辉2,蒲文娟3,杨胥1   

  1. 1. 西安电子科技大学
    2. 陕西省 西安电子科技大学
    3.
  • 收稿日期:2018-03-21 修回日期:2018-08-17 出版日期:2018-10-18 发布日期:2018-10-18
  • 通讯作者: 袁江伟 E-mail:710323551@qq.com

Hybrid beamforming with discrete phase shifters for millimeter wave backhaul networks

  • Received:2018-03-21 Revised:2018-08-17 Online:2018-10-18 Published:2018-10-18
  • Contact: Jiang-Wei YUAN E-mail:710323551@qq.com

摘要: Hybrid beamforming (HBF) technology becomes one of the key technologies in the millimeter wave (mmWave) mobile backhaul systems, for its lower complexity and low power consumption compared to full digital beamforming (DBF). Two structures of HBF exist in the mmWave mobile backhaul system, namely, the fully connected structures (FCS) and partially connected structures (PCS). However, the existing methods cannot be applied to both structures. Moreover, the ideal phase shifter is considered in some current HBF methods, which is not realistic. In this paper, a HBF algorithm for both structures based on the discrete phase shifters is proposed in the mmWave mobile backhaul systems. By using the principle of alternating minimization, the optimization problem of HBF is decomposed into a DBF optimization problem and an analog beamforming (ABF) optimization problem. Then the least square (LS) method is enabled to solve the optimization model of DBF. In addition, the achievable data rate for both structures with closed-form expression which can be used to convert the optimization model into a single-stream beamforming optimization model with per antenna power constraint is derived. Therefore, the ABF is easily solved. Simulation results show that the performance of the proposed HBF method can approach the full DBF by using a lower resolution phase shifter.

关键词: millimeter wave backhaul networks, fully connected structure, partially connected structure, hybrid beamforming, limited phase shifters resolution

Abstract: Hybrid beamforming (HBF) technology becomes one of the key technologies in the millimeter wave (mmWave) mobile backhaul systems, for its lower complexity and low power consumption compared to full digital beamforming (DBF). Two structures of HBF exist in the mmWave mobile backhaul system, namely, the fully connected structures (FCS) and partially connected structures (PCS). However, the existing methods cannot be applied to both structures. Moreover, the ideal phase shifter is considered in some current HBF methods, which is not realistic. In this paper, a HBF algorithm for both structures based on the discrete phase shifters is proposed in the mmWave mobile backhaul systems. By using the principle of alternating minimization, the optimization problem of HBF is decomposed into a DBF optimization problem and an analog beamforming (ABF) optimization problem. Then the least square (LS) method is enabled to solve the optimization model of DBF. In addition, the achievable data rate for both structures with closed-form expression which can be used to convert the optimization model into a single-stream beamforming optimization model with per antenna power constraint is derived. Therefore, the ABF is easily solved. Simulation results show that the performance of the proposed HBF method can approach the full DBF by using a lower resolution phase shifter.

Key words: millimeter wave backhaul networks, fully connected structure, partially connected structure, hybrid beamforming, limited phase shifters resolution