本計畫研究方向主要定位在降低錯誤率以達更高的傳輸速率，並且能快速建立基地台與行動端的連接，同時增加頻譜效能等三項目標進行對第四代無線通訊的研究。本計畫將要研發的幾項核心技術包括：頻帶偵測(spectrum sensing)、蜂巢搜尋(cell search)與扇區搜尋(sector search)以及正交分頻多工系統之頻率漂移補償技術，子載波擷取技術與通道檢估技術。以上各項研究均基於前幾年計畫有部分研究成果，試圖在本計畫作更深入與完整的研究。當行動端在進行移動時，首先必須確認基地台所發送的同步訊號，以完成扇區搜尋；確認所屬扇區後，再利用補償後之訊號進行蜂巢辨識。當有來電或撥出動作時，則需於接收機進行通道檢估以便等化後續傳輸時的通道影響。目前LTE在上行鏈路中是規範相鄰式子載波分配(localized chunk permutation)。但在近年研究中也可以看到為了利用頻譜多樣性增加子頻分集所做的分散式的子載波分配(distributed chunk permutation)的研究。本計畫除了嘗試採用前幾年計畫中所開發出的頻域通道檢估技術外，也將利用在前幾年的計畫中所研發出的後置虛擬亂數正交分頻多工中時域上通道檢估技術進行新式技術研發，以便解決分散式的子載波分配造成的現有技術問題，並推展於高速移動環境之正交分頻多工行動通訊系統。同時為了使得頻帶受到有效率的使用，載波集成技術(carrier aggregation)也受到了關注。本計劃將利用頻帶偵測技術來偵測空閒頻帶以便供給載波集成之用。 OFDM technologies have focused a lot of research effort in academia and received substantial research and development attention in industry because they are expected to be the core technologies in the 4G standards of mobile communication in the near future. In this project, the primary purposes are to develop effective techniques of spectrum sensing, cell/sector search and channel estimation (CE) in practical mobile OFDM environments, then try to apply these methods to make carrier aggregation work. Meanwhile, the core and essential transceiving technologies and techniques, such as cell search, sector search, time-synchronization in OFDM, frequency offset estimation/compensation in OFDM, CE and equalization in OFDM will be deeply and thoroughly investigated. These techniques are studied in our preceding NSC research projects, and many preliminary outcomes were also learned to furthermore pursue much advanced research. Therefore, in this research, we not only deeply and thoroughly investigate current 4G techniques, but also consider the MIMO and distributed-chunk CE; meanwhile, in order to enhance the spectrum efficiency, the spectrum sensing and carrier aggregation techniques will be taken in to serious investigation. These important and essential techniques will be researched in theory and in practice in this research project. 研究期間：10008 ~ 10107
