在無線通訊系統上由於各使用者與基地台的位置不相同，我們需得知相關的測距資訊，來達到系統的要求。本論文分成兩系統來討論， 一個為雷達系統，另一個為初始測距的OFDMA系統。 調頻連續波(FMCW)雷達利用在時間上改變發射訊號的頻率，並測量接受信號與發射訊號頻率間的差值來測定目標距離與速度等資訊。本論文主要研究如何設計調頻連續波訊號波形，以有效抗干擾並能測得目標訊號的距離與速度資訊。 使用者與基地台建立通訊需要得知關於同步的參數，利用正交分多工接進系統的初始測距在基地台上可接收到關於時間與頻率的訊號，並利用此訊號搭配ESPRIT 演算法進一步求得關於測距的同步參數。本論文運用其他類似ESPRIT的演算法，並同時偵測出頻率位移和時間延遲，而目前的演算法[24]需利用不同的訊號處理再分別求出頻率位移和時間延遲。Because the position of every user is varied from the base station, we may need to know the related ranging information which may be required for the system. The thesis is divided into two parts. The first part is the algorithm designed for radar systems. The second part is the initial ranging algorithm design for OFDMA systems. FMCW radar utilizes the technology by changing frequency in time from the transmitter. By way of the time difference and Doppler frequency between the transmitted and received signals, we can obtain the information about distance and velocity. The purpose of this part in the thesis is to design an FMCW signal which can resist to interferences while retain the capability of detecting the distance and velocity. An initial ranging estimation scheme for OFDMA systems is proposed as users intend to establish communication link with the base station (BS) by utilizing spreading in both the time and the frequency domains. The synchronization parameters can be estimated by using the ESPRIT algorithm. We will use a similar ESPRIT algorithm to estimate timing delay and frequency offset simultaneously. In [15], the estimation of the timing delay and the frequency offset requires two sets of signals for processing separately to achieve to this task.
