相關性通道下混合多輸入多輸出系統之適應性調變及傳輸架構

在新世代無線通訊中，利用多天線傳輸架構可以比單天線傳輸架構擁有更優越的效能以及更佳的系統容量，適應性混合多輸入多輸出系統是一種多天線無線通訊傳輸架構，其接收端回傳有限的資料給傳送端，運用不同的調變、編碼、功率與天線分配去適應不同的通道狀況，藉以提高系統效能以及傳輸容量。對傳統混合多輸入多輸出系統而言，任一傳輸架構皆是由不同的編碼架構所組成，而這些編碼架構效能皆不盡相同，因此單一調變方式的傳輸架構並不全然適用於各種通道條件，因此本論文針對混合多輸入多輸出系統架構，透過簡單的適應性調變演算法，在特定的通道條件下得到最佳的調變方式組合，期望能在固定的資料傳輸量之下，達到較佳的錯誤率。傳統適應系統必須透過提高調變階層來提升系統容量，但對於多輸入多輸出系統而言，多輸入多輸出系統可以提供分集增益及多工增益，舉例來說塊狀時空碼可提供單純的分集增益，而VBLAST則有單純的多工增益，但分別要在低訊雜比與高訊雜比的通道環境下其效益才能彰顯，因此多天線系統在高訊雜比環境下，可以利用空間多工來增加系統容量。本論文利用塊狀空時碼-VBLAST的架構，在不同的訊雜比下運用不同比例的編碼、功率與天線分配，以及考慮通道相關性對多天線系統所造成的影響，並利用其特性來調整傳輸天線架構的組合，並且在特定的通道條件及訊雜比下選擇合適的傳輸架構，提高系統的傳輸容量。

關鍵字

相關性通道；塊狀空時碼； VBLAST ；適應性調變；適應性混合多輸入多輸出系統

並列摘要

Multiple-Input Multiple-Output (MIMO) system is one of methods for increasing system capacity and reliability in high data rate wireless communications. Adaptive hybrid MIMO system is a scheme of multi-antenna wireless communication. The receiver can feedback limited data to the transmitter and the transmitter utilizes different modulations, codes, power, and antenna allocation to achieve the best performance and maximize the throughput under the different channel situation. For the conventional hybrid MIMO system, the BER in different transmission scheme is dissimilar. A single modulation order doesn’t suit to all hybrid MIMO systems. Hence, for the different schemes and channels, we use an adaptive modulation algorithm for a MIMO system to minimize BER under a fixed data rate. Traditional adaptive systems enhance the throughput of the system by increasing the modulation orders. The multi-antenna can provide the diversity gain (STBC) and multiplexing gain (VBLAST) and their benefits can be revealed when working at the high SNR and low SNR separately. Hence, we can use the spatial multiplexing to increase the system throughput. Therefore, we propose an adaptive hybrid MIMO transceiver scheme in a fixed transmission antenna system. The transmitter is based on power allocation and antenna allocation with both average SNR and partial channel state information (CSI) feedback to maximize the throughput.

並列關鍵字

Spatial Correlated Channel ； STBC ； VBLAST ； Adaptive Modulation ； Adaptive Hybrid MIMO System

參考文獻

[1] S, M. Alamouti, “A Simple Transmit Diversity Scheme for Wireless Communications,” IEEE J. Select. Areas Commun., vol. 16, pp. 1415-1458, Oct. 1998.

[3] P. W. Wolniansky, G. J. Foschini, G. D. Golden, and R. A. Valenzuela, “V-BLAST: An Architecture for Realizing Very High Data Rates Over the Rich-Scattering Wireless Channel,” in Proc. International symposium on signals, systems and Electronics, Sept. 29-Oct. 2, 1998, pp. 295-300.

[4] G. J. Foschini, “Layered Space-Time Architecture for Wireless Communication in a Fading Environment When Using Multi-Element Antennas,” Bell Labs Tech. J., vol. 1, no. 2, pp. 41-59, 1996.

[6] Walter da C. Freitas Jr., R. P. Cavalcanti, and Renato R. Lopes, “Hybrid Transceiver Schemes for Spatial Multiplexing and Diversity in MIMO Systems,” Journal of Communication and Information Systems, vol. 20, no. 3, 2005.

[8] Ham Jaesang et al., “An Adaptive Modulation Algorithm for Performance Improvement of MIMO ML Systems,” IEEE Commun. Lett., vol. 12, no. 11, pp. 819-821, Nov. 2008.

國際替代計量

相關性通道下混合多輸入多輸出系統之適應性調變及傳輸架構

未授權

主題瀏覽