近年來，由於合作式通訊技術可以提供空間分集，並且在無線通訊上能夠有效降低通道衰減的影響而不增加行動裝置的複雜度，因此受到許多重視。合作式通訊的概念主要是多用戶將他們的資源做整合，透過閒置的行動裝置作為中繼站，幫助傳送端傳送資料，這種中繼站網路形成一個分散式的虛擬天線陣列。然而，高資料傳輸率的正交分頻多工技術需要通道狀態資訊。因此，在合作式通訊藉由正交分頻多工的通道估測將會是一項挑戰。在假設所有節點之間的通道都為暫態穩態並為平坦衰減的前提之下，我們的估測方式是在放大前傳的中繼站網路中，將原本串接的傳送端到中繼站再到接收端連線的通道狀態資訊拆解成從傳送端到中繼站以及中繼站到接收端。並介紹通道估測的方法，如：最小平方以及最小均方誤差的演算法，做出一些比較以及討論 Cooperative communications have been interesting popularity recently since spatial diversity can be provided so as to mitigate fading over wireless transmission without hardware complexity of mobile devices. Multiple users pool their resources form a virtual antenna array that realizes spatial diversity gain in distributed fashion. However, high data rate transmission with orthogonal frequency division multiplexing (OFDM) requires the channel state information (CSI), and therefore OFDM channel estimation for cooperative communication can be a challenging problem. Consider that all channels between each node are assumed to be quasi-stationary frequency-flat fading. We use a channel estimation scheme for destination to disintegrate the CSIs of source to relay (S-R) link and relay to destination (R-D) link from the cascaded S-R-D link in amplify-and-forward (AF) relay networks. The channel estimation error of the proposed scheme is also analyzed. Especially, least square (LS) algorithm and minimum mean square error (MMSE) algorithm for the CSI estimation of source to destination and relay to destination link are compared.
