蜂巢式通訊網路下毫米波通道之建模與估計

Abstract

為應付蜂巢式通訊網路的容量需求持續地增加，新的實體層的技術也不斷的推出， 如垂直扇區(vertical sectorization) ， 三維波束成形（ 3D beamforming）、協調多點(coordinated multipoint)和大規模的多輸入多輸出(large-scale MIMO)等皆是。但由於頻寬有限，這些新技術所能增加的容量仍十分有限。因此有大量頻寬的毫米波（mmWave）頻段便變成滿足容量需求最合理的選擇。 為了正確地開發和評估新技術的系統性能(尤其是在毫米波頻帶中)，符合實際狀況的通道模型是迫切需要的。在本論文的第一個部分中，我們依據最新的文獻，開發了一個由3GPP_LTE標準所訂定的三維通道為基礎的模擬平台。這個平台包括幾個最知名的通道模型，亦即3GPP-LTE-A標準所制定的微波通道模型、歐盟METIS-2020計畫跟據前者所研發出來的改良版以及由紐約大學團隊經多次測量後所建議的毫米波通道模型。為驗證我們發展的平台之正確性，我們比較了一些我們所產生的與已知統計曲線。 我們接著利用此模擬平台來研究一個配有大型均勻線性陣列天線的基地台（BS）服務許多裝有單天線移動用戶之大規模多輸入多輸出分時多工（TDD）單細胞系統的通道估計問題。我們首先探討窄頻帶的多集群通道的情況下，入射波有多個不同的抵達平均角度(AoA)且各自有不相同的入射角度擴散(AS)。最後，我們提出了一種基於降秩(reduced rank)模型的方法，來解決了寬頻帶通道估計的問題。這些方法都透過我們建立的通道模擬器加以驗證。

Continue capacity demand in cellular communications has stimulated new air interface concepts and technologies such as vertical sectorization, three-dimensional (3D) beamforming coordinated multi-point and large-scale MIMO. It is the main driving force for the consideration of millimeter wave (mmWave) bands and the advances in the associated circuits and devices technologies. In order to properly develop and evaluate the system performance in mmWave bands, a realistic channel model is urgently needed. In the first part of this thesis, we develop a 3GPP standard compatible 3D channel simulation platform that encompasses two most known mmWave channel models, namely those specified by the 3GPP-LTE-A standard and suggested by Rappaport of NYU. Given the simulation model and reported measurement results, we then consider the channel estimation issue in a single-cell time division duplexing (TDD) massive MIMO system with a base station (BS) equipped with a large uniform linear array serving many single-antenna mobile users. We first treat the narrowband multi-cluster channel case where the incoming waveform arrives at different mean angles of arrival (AoA) with non-identical angle spread (AS). Finally, we propose a model-based approach to solve the wideband channel estimation problem. Various simulated examples are given to validate the proposed solutions.