在混合式衛星-地面網路中具分散式時空編碼之合作式中繼策略

Cooperative Relaying Strategies with Distributed Space-Time Coding in Hybrid Satellite-Terrestrial Networks

賴玉庭(Yu-Ting Lai)

指導教授 ： 溫志宏

共同指導教授 ： 許孟烈(Meng-Lieh Sheu)

國立暨南國際大學/科技學院/通訊工程研究所/碩士(2011年)

摘要

混合式衛星-地面網路(Hybrid Satellite-Terrestrial Network, HSTN)即是將衛星通訊系統(Satellite Communication System, SCS)與地面通訊網路(Ground Communication Network, GCN)作結合。藉由整合衛星通訊系統與地面通訊網路兩者的優點，為多媒體廣播與群播服務(Multimedia Broadcast and Multicast Service, MBMS)提供一個無死角的全方位傳輸平台。合作式通訊(Cooperative Communication)的地面站中繼傳輸策略可以較低的傳送端及接收端複雜度得到類似多輸入多輸出(Multiple Input Multiple Output, MIMO)技術的效果，達到分集增益。而時空編碼(Space-time Coding, STC)亦可以簡單地利用時間以及空間的多樣性。
本論文中，我們先以衛星傳輸通道與地面中繼站傳輸通道皆為雷利衰減(Rayleigh Fading)之通道模型為系統訊號傳輸通道。為了讓系統訊號傳輸通道更符合混合式衛星-地面網路當中，衛星傳輸通道之直視路徑(Line of Sight, LOS)特性，我們將衛星傳輸通道改以萊斯衰減(Ricean Fading)通道為通道模型。
我們在具有分散式時空碼(Distributed Space-time Coding, DSTC)的地面中繼站分別執行放大後傳送(Amply and Forward, AF)以及解碼後傳送(Decode and Forward, DF)兩種中繼傳輸策略。在目的端接收架構則分別使用選擇性合成法(Selective Combining, SC) 以及最大比例合成法(Maximum Ratio Combining, MRC)。我們以符元錯誤率比較兩種訊號合成方法所帶給系統之分集增益(Diversity Gain)效果，並分配衛星訊號源與地面中繼站之傳輸功率比例。由模擬結果我們發現，系統之頻寬效益增加，且符元錯誤率降低，系統效能獲得改善。

關鍵字

合作式通訊 ； 混合式衛星-地面網路 ； 分散式時空碼 ； 放大後傳送 ； 解碼後傳送 ； 最大比率合成法 ； 選擇性合成法

並列摘要

Hybrid Satellite-Terrestrial Network (HSTN) is the integration of the Satellite Communication System (SCS) and the Ground Communication Network (GCN). It can provide a communication platform without dead zone for Multimedia Broadcast and Multicast Service (MBMS) by using the advantages of the SCS and the GCN. The cooperative relaying strategies for terrestrial stations make it possible to achieve the diversity gain similar to the Multiple Input Multiple Output (MIMO) technique with less complexity of transmitters and receivers. The Space-time Coding (STC) technique can also use the time diversity and the spatial diversity simply.
In the thesis, we took the Rayleigh Fading channel model as the transmitting channel of the satellite and the terrestrial first. And then we took the Ricean Fading channel model as the transmitting channel of the satellite. Because the signals transmitted by the satellite have a strong Line of Sight (LOS) property.
Then we applied two relaying strategies, Amply-and-Forward (AF) and Decode -and-Forward (DF), separately on the terrestrial relay stations with Distributed Space-time Coding (DSTC). And at the receiver of the destination, we used the Selective Combining (SC) method and the Maximum Ratio Combining (MRC) method separately. We compared the effect of Diversity Gain caused by the two signal combining methods with the Symbol Error Rate (SER). We also did the power allocation of the satellite and the relays. By the simulations, we found out that the system has the better bandwidth efficiency and the SER is lower. The system performance was improved.

並列關鍵字

Cooperative Communications ； Hybrid Satellite-Terrestrial Networks ； Amplify-and-Forward ； Decode-and-Forward ； Maximum Ratio Combining ； Selective Combining

參考文獻

參考文獻

[1] K. Etemad and L. Wang, “Multicast and broadcast multimedia services in mobile WiMax networks,” IEEE Commun. Mag., vol. 47, pp. 84–91, Oct. 2009.

[2] S. Parkvall, E. Englund, M. Lundevall, and J. Torsner, “Evolving 3G mobile systems: broadband and broadcast services in WCDMA,” IEEE Commun. Mag., vol. 44, pp. 30–36, Feb. 2006.

[3] H. Du, L. Fan, U. Mudugamuwa, and B. G. Evans, “A cross-layer packet scheduling scheme for multimedia broadcasting via satellite digital multimedia broadcasting system,” IEEE Commun. Mag., vol. 45, pp. 94–101, Aug. 2007.

[4] S. Kim, H. W. Kim, K. Kang, and D. S. Ahn, “Performance enhancement in future mobile satellite broadcasting services,” IEEE Commun. Mag., vol. 46, pp. 118–124, Jul. 2008.