- 學位論文
以強制零化為基礎適用於MIMO干擾通道之波束形成器設計
A Zero-Forcing Based Beamformer Design for MIMO Interference Channels
摘要
在現今通訊發達的時代，單輸入單輸出系統已經不符合實際需求，無線通訊中，為了提高通道速率，多輸入多輸出(MIMO)系統可以同時發送接收多種訊號，然而由於系統更於複雜，現今論文提出了許多調變技術實現於多輸入多輸出系統，然而系統複雜導致演算法過於複雜，這樣會造成硬體實現上的困難，為了簡化計算上的複雜度，本論文將針對這問題去做改善。 在近年來的文獻，所使用的通道模型為三用戶高斯干擾通道，主要針對發送端和接收端配置相同天線數目去做研究，設計 beamforming vector 在發送訊號時可以達到最高的通道速率。近年性能表現較佳的文獻主要利用 beamforming vector 達到干擾訊號對齊。在本論文提供一個新的演算法，主要研究當發送端和接收端配置不同的天線數目時，亦能產生好的性能表現。 本論文提出 Interference ZF 演算法，主要利用Zeroforcing 技術消除其他用戶造成的干擾，使用此技術不需要先將干擾訊號對齊，即可以直銷除干擾訊號趨近於零。因此演算法最大的優點是不需要過於複雜的計算和時間即可設計出最佳的 beamforming vector。 由於近期文獻所提供的演算法在增加天線數目的時候，會有迴圈次數過多導致耗時過久的問題，本論文所提出的 Interference ZF 演算法即使增加天線數目，依然迅速有效率地找出 beamforming vector 消除干擾訊號，不會因為增加天線數目導致消除干擾訊號時過於複雜，也就是說，增加了天線數目也不會增加 Interference ZF 演算法的複雜度且不影響 Interference ZF 演算法的性能表現，如此在硬體的實現上，更為可行。
並列摘要
Nowadays, single-input single-output systems no longer meet the actual demand of high data rates. In wireless communications, in order to improve the channel rate, multiple-input multiple-output (MIMO) system, which can simultaneously send and receive a variety of signals is proposed. However such a system is more complex, and current literatures propose numerous modulation techniques implemented in a multi-input multi-output system to increase the efficiency. The complexity of MIMO leads to much more complex algorithms, which result in difficulties in making the hardware. In order to simplify the complexity in algorithms, this thesis proposes a new approach to better solve the problem. In recent literature, the channel model used is the 3-User Gaussian interference channel, where transmitters and receivers are equipped with the same number of antennas. Algorithms that provide better performance in recent literature mainly use beamforming vector to achieve interference alignment. This thesis provides a new method that can produce good performance when transmitter and receiver have the different number of antenna configurations. Interference ZF algorithm proposed in this thesis mainly uses Zeroforcing technique to eliminate interference caused by other users. This technique does not require interference alignment. It performs interference cancellation which the interference signal approaches zero. The biggest advantage of this algorithm is it does not require complex systems and time to design the optimal beamforming vector. Algorithms found in recent literature involve large number of looping when the number of antennas increases. This leads to time-consuming problem. Interference ZF algorithm proposed in this paper is able to locate beamforming vector which eliminates interfering signals quickly and efficiently when the number of antennas is increased. At the same time, this means that increasing the number of antennas does not increase the complexity of Interference ZF algorithm and does not affects the performance of Interference ZF algorithm. Hence, it is easier to realize in hardware.