於60Ghz 無線電傳輸下的空時前置編碼混合式波束成形架構及基於方向的前置編碼器碼書設計

Abstract

在 60Gh 無線電傳輸下，探討使用平面貼片天線陣列、混合式射頻及基 頻波束成形技術的一個有效率的架構。在此架構下，一個具備空時及前置 編碼的混合式波束成形架構被用來有效利用在60Ghz 無線電傳輸下非直視 路徑傳輸造成的空間分歧性。此外，一個有效率的單位元迴饋波束成形架 構被提出來找出能夠支援直視路徑傳輸、最適合射頻波束成形所打的方 向。模擬結果顯示提出的混合式波束成形架構相對於射頻波束成形架構能 在訊號雜訊比上了提供5~10db 的增益。此外，使用基於方向設計的前置編 碼器碼書及單位元迴饋波束成形機制的效能在100 次遞迴次數內收斂接近 於直視路徑的效能，顯示出其遠比利用窮舉法的搜尋方式有效率的優點。 此外，在對前置編碼器量化的情況下，使用提出的前置編碼器碼書的效能 與未對前置編碼器量化的效能相當接近。

A cost-effective architecture is studied for a joint radio frequency (RF) and baseband hybrid beamforming (HBF) method that uses planar antenna arrays (PAA) in 60GHz radio transmission. Under the hybrid architecture, a space-time precoded HBF scheme is presented to exploit the spatial diversity for non line-of-sight transmission in 60GHz radio. Furthermore, an efficient one-bit feedback (OBF) beamforming (BF) scheme combined with direction-based precoder codebook design criterion is proposed to search for the pointing directions of each RF beamformer (BFer) of the HBF architecture. Simulation results show that the proposed HBF architecture can provide a 5 ~ 10dB gain in the signal to noise ratio compared to an architecture that uses the RF BF only. In addition, the OBF BF scheme with the direction-based precoder codebook converges close to the LOS transmission in 100 iterations, which is much more efficient than exhaustively searching for the BF directions. With the quantization of optimal precoder utilizing the proposed precoder codebook, the performance is similar to that of the optimal precoder without quantization.