正交分頻多工系統在3GPP LTE-A系統中載波聚合下之時間與頻率偏移估測

Abstract

Abstract In recently years, orthogonal frequency division multiplexing (OFDM) has become a popular technique in air interface of wireless communication. With high flexibility to subcarrier allocation, modulation and coding scheme, many wireless communication standards has adopted. However, although OFDM has above significant features, it is still sensitive to the effect of timing and frequency error. LTE-Advanced is a new coming mobile cellular communication technology whose physical layer technique uses OFDM. One new technical component of LTE-Advanced is carrier aggregation which is our main concern in this thesis. Recently, most studies about carrier aggregation focus on MAC or upper layer, and there is rare study on physical layer under carrier aggregation. In this thesis, we want to study the OFDM physical layer synchronization problem with carrier aggregation and to see how effect of carrier aggregation is on OFDM synchronization. An intuitive concept is that, with carrier aggregation, more component carriers mean that we have more extra information to solve synchronization problem which is better than one without carrier aggregation. In this thesis, we derived CP-based and Preamble-based method in single RF chain and multiple RF chains under carrier aggregation. According to the simulation results, the synchronization algorithm we derived can really do better than one without carrier aggregation. Furthermore, the performance improvement of CP-based method with carrier aggregation is more remarkable than improvement of Preamble-based method.