合作式通訊是近年被廣泛討論的技術，可以有效降低中斷機率並且增加能源使用效率，適合應用於綠能無線網路。但是過往的研究多假設中繼節點願意無條件的幫助傳輸，這樣的假設顯然並不合理。為此，本實驗室先前提出了名聲拍賣賽局的機制，利用間接互惠的概念，刺激使用者來協助進行合作傳輸。但是，當整體的能源使用被限制的時候，越多的中繼節點反而無法發揮效能，無法充分發揮合作式通訊的優點。
基於此，本研究提出一個新的名聲拍賣機制，結合最近被廣泛討論的虛擬波束成形技術。虛擬波束成形技術利用多個中繼節點來協助傳輸訊號，形成一道訊號波束，藉此提高接收訊號的強度，而因為近年來通道估測技術的進步，虛擬波束成形技術也變得可行。本研究將依據虛擬波束成形技術，提出一個較為簡單的中繼節點選擇方案，並為了更進一步提高效能，本研究也設計兩個最佳中繼節點數量選擇法以及動態功率選擇法的方案。最後的結果顯示，雖然簡單方案的效能略遜於先前的機制，但是設計以及運行的成本也較低，整體是可以接受的，並且效能會隨著參與合作的中繼節點數量增加而上升也證明了此機制受惠於合作式通訊的分集多樣性，改善先前研究所提出機制的不足。另外結果也顯示，動態功率方案的效能，無論是中斷機率或是功率消耗，都比先前研究所提出的機制還要好，說明使用虛擬波束成形技術可以提高合作式通訊網路的效能，並且也證明我們所提出的機制同時是可靠與節能的。

Cooperative communication is a simple but effective scheme that can reduce outage probability and power consumption for next-generation green wireless networks. However, in cooperative networks, the assumption that all users of a wireless network would be willing to help transmit is not realistic. Based on this, our laboratory’s previous work proposed a reputation auction game to stimulate users to perform cooperative transmission via the concept of indirect reciprocity. However, the simulation and analysis results indicated that the performance of multiple-relay cooperation scheme was not better than single-relay scheme, neither in outage probability or energy consumption.
Accordingly, we proposed a cooperation scheme by exploiting virtual beamforming to improve the performance in multiple-relay transmission scheme. Virtual beamforming is a multiple-input single-output (MISO) system which utilizes multiple relays to form a beam. It became feasible because of the progress of channel estimation technology. Based on virtual beamforming, a simple relay selection algorithm was designed to allocate reputation and power. To achieve higher performance, two adaptive and dynamic power algorithms were also proposed. Finally, we compared our auction game with previous work via computer simulation. The simulation results demonstrated that the proposed scheme outperforms previous work. The results have also shown that cooperative communication networks can benefit from virtual beamforming technology and our auction game is both reliable and energy saving.

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