整合毫米波多用戶混合式波束成型與基於天線元件分配之空間調變設計

Abstract

由於專用射頻鏈(RF chain)的高成本和低能量效率，在現實場景中，RF鏈的數量通常在毫米波(mmWave)頻段大規模多輸入多輸出(massive MIMO)系統中受到限制。於是提出了將數字基帶預編碼 (Digital Baseband Precoding)和模擬波束成形(Analog Beamforming)相結合的混合波束成形(Hybrid Beamforming)，作為此類系統的可行解決方案。空間調變(Spatial Modulation)利用了多輸入多輸出系統的空間分集，是另一種低成本，省電的技術。 在本文中，我們將混合波束成形與空間調變系統相結合，以在不增加成本的情況下提高大規模多輸入多輸出系統的效率。我們也考慮了多用戶場景，並藉由我們設計的天線元件分配(Antenna Element Allocation)降低用戶之間的碰撞機率，進而提升系統的效能。並且透過數學理論，預先分析兩個系統的性能比較，以幫助系統在不同參數下的AEA-SM和SM傳輸模式之間進行選擇。

Due to the high cost and low energy efficiency of dedicated radio frequency (RF) chains, in practice, the number of RF chains is usually limited in millimeter wave (mmWave) massive multiple input multiple output (MIMO) systems. Hybrid beamforming (HB), combining digital baseband precoding and analog beamforming, was proposed as viable solution for this kind of systems. Spatial modulation (SM) is another low cost and power efficient technique that can exploit spatial diversity of MIMO systems. In this thesis, we will combine hybrid beamforming with SM to improve the efficiency of massive MIMO without additional cost. Compared with the traditional SM system that uses less modulation order and has relatively better performance, the hybrid beamforming with spatial modulation (HBSM) system is not exactly like this. Considering the multi-user scenario, we propose an antenna unit allocation design that can reduce the possibility of conflicts between users, thereby improving performance. The performance comparison of the HB-SM system and the antenna element allocation of hybrid beamforming with spatial modulation (AEA-HB-SM) system is analyzed off-line through mathematical formulae to help the system choose between AEA-HB-SM and HB-SM transmission modes under different parameters.