MIMO 系統之訊號設計、通道估計與符元偵測

Abstract

本論文針對無線網路中的多天線系統（多輸入多輸出系統），進 行接收端演算法之研究。主題包括通道估計，訊號解調，以及消除其 他使用者之干擾。本論文共分七大章節。在第三章中，論文提出新的 無線通道模型。此模型利用無線通道在時間，頻率和空間的相關性， 大幅降低需要估計之參數。這種模型可用於低複雜度的信道估計，亦 可用於低複雜度的編碼選擇演算法。在第四章中，論文討論通道估計 的錯誤以及對訊號解調的影響。論文提出整合通道估計以及訊號解調 的機制。此機制可大幅降低對通道估計錯誤的不確定性。在第五章中， 論文討論使用者干擾以及對接收端的影響。論文提出新的抗干擾機制。 此演算法充分利用干擾中的訊號型態、發生的時間、以及頻段，藉此 消除干擾之影響。提出機制可優於傳統消除方式，並且可操作於與干 擾基地台非同步的情形。在論文第六章中，論文針對天線調變傳輸機 制。此機制使用較少的高頻電路元件，藉此提供較高的節能效率。論 文提出改進的空間調變演算法，此方法可明顯增強的頻譜效率。其中 關鍵技術為利用選擇不同的調變方式，藉此傳送更多的資訊。

The aim of this thesis is to investigate multiple input multiple output (MIMO) techniques from the reception algorithms to the advanced spatial modulation (SM) transmission schemes. In the reception algorithms, the proposed schemes are derived based on the detection theory, i.e., maximum likelihood, linear minimum mean square error, successive interference cancellation, combining with the statistical analysis, i.e., Bayesian linear regression and Bayesian model comparison, in order to deal with the channel uncertainty, i.e., fading, correlations, thermal noise, multiple interference, and the impact of estimation errors. In the transmission schemes, the signal constellations are targeted to find a good trade-off between the transmit energy and the minimum Euclidean distance in the signal space. The proposed schemes, denoted by enhanced SM, introduce novel modulation/antenna combinations and use them as the information bits for transmission. The number of those combinations is the double or the quadruple of the number of active antenna indices (or index combinations) in conventional SM systems, and this increases the number of bits transmitted per channel use by one or two. The results of simulations show that good system performance can be achieved with the advanced MIMO techniques. Several examples are presented in this thesis to provide insights for the MIMO system designs.