隨著無線通訊技術的發展與進步，不管是第四代LTE（Long Term Evolution）行動通訊或第五代行動通訊中，正交分頻多工（Orthogonal Frequency Division Multiplexing, OFDM）的技術依然扮演十分重要的角色。 本論文將會旨在以可參數控制分時雙工（Time Division Duplexing, TDD）的正交分頻多工之上行與下行鏈路系統與其調變原理做介紹，也會著墨在主（Slave）從（Master）系統之間的溝通與參數控制模式及訊框同步。將以軟體定義無線電（Software Defined Radio, SDR）方式設計並實現上行及下行鏈路系統的發射機與接收機，在整合到主從系統後，實現即時的在同一頻率不同時間上，完成使用者與基地台之間的溝通。並在時域上以第三方來觀測主從系統傳收的訊號分布狀況；又以觀測經過通道後不同增益帶來的影響，來探討本論文系統的品質。 ;With the advancement of wireless communication technology, whether the 4G-LTE (Long Term Evolution) mobile communications or 5G mobile communications, Orthogonal Frequency Division Multiplexing (OFDM) technology still plays a very important role. The main purpose of the paper is to introduce OFDM uplink and downlink system and its modulation principle with parameter control of Time Division Duplexing (TDD). It will also focus on the communication between master–slave system, the parameter control mode and frame synchronization. The transmitter and receiver of the uplink and downlink system will be designed and implemented on Software Defined Radio (SDR). After being integrated into the master-slave system, the communication between the user and the base station can be completed at the same frequency and different time in real time. Use a third party to observe the distribution of the signal transmitted and received in the time domain; and observe the influence of different gains after passing through the channel to discuss the quality of the system in this paper.
