多用戶多輸入多輸出( MU-MIMO )技術通過將終端設備組合起來以實現基地台可利用最大可用帶寬同時服務終端用戶組，解决單用戶MIMO系統中占用時頻資源的問題，在提高系統傳輸速率的同時也能保證較好的網絡覆蓋。在具有長距離的衰落信道中，中繼在無綫通信系統中充當著儲存轉發來自信源到信宿之間信息的作用。因此對于例如企業網絡這類具有較廣泛距離的多用戶終端傳輸系統，可以通過設置多個不同的中繼來實現覆蓋範圍內基地台與用戶終端之間的最佳通信。 但在進行信道估計的時候，由於涉及到對信道的協方差矩陣求逆的過程，通過多中繼改善信道質量的同時也增加了信道估計的計算複雜度。因此本文提出一種基于多中繼多用戶MIMO系統上行信道反饋機制中，當多個用戶共享同一導頻序列時，根據接收信息進行導頻降維以降低信道估計複雜度的設計。研究表明，通過對多中繼優選方案得到的導頻序列在信道估計中的表現接近于同時考量所有中繼節點信息得到的導頻序列，但較之節約了時頻資源，提高了系統的頻譜利用率。;Multi-user multiple-input multiple-output ( MU-MIMO ) technology by combining the terminal equipment to achieve the base station can use the maximum available bandwidth at the same time service terminal user group, solving the problem of time-frequency resources in single-user MIMO system. Speeding data rates while also ensuring better network coverage. In a fading channel with a long distance, the relay acts as a means of storing and transferring information from the source to the destination in the wireless communication system. Therefore, for multi-user terminal transmission systems with a wide range of distances such as enterprise networks, the best communication between the base station and the user terminal can be achieved by setting a plurality of different trunks. However, when the channel estimation is carried out, the complexity of the channel estimation is increased by improving the channel quality by multi-relay due to the process of inverting the covariance matrix of the channel. Therefore, this paper presents a design based on MU-MIMO relay system uplink channel feedback mechanism, when multiple users share the same pilot sequence, according to the received CSI( channel state information ) to reduce reduce the complexity of the pilot design. The results show that the performance of proposed algorithm pilot design for training-based channel estimation approximate conventional pilot，but it improves the time-frequency resources and improves the system Spectrum utilization.
