# <center> **Daily Report 5** </center> ###### tags: `O-RAN` `IVC` `5G O-RAN` `ITB NTUST 5G course` > Date: 23/07 ## <center> **Baseband Technology (OFDMA)** </center> ### **Important Aspects** #### **1. Baseband Technology (Basic Principles of OFDM & OFDMA)** #### **2. OFDM System** #### **3. Modulation and Demodulation** ### **Summary** OFDM is a multiplexing technique that divides the available bandwidth into multiple orthogonal sub-carriers. Each sub-carrier can be modulated independently and carries different information. FDM stands for Frequency Division Multiplexing. OFDM stands for Orthogonal Frequency Division Multiplexing. In FDM, Bandwidth (B) is committed to the different sources. In OFDM, Single data source attaches all the sub-channels. Applications of FDM are in radio and satellite communication. Applications of OFDM are in LTE technologies and broadband internet. The Characteristics OFDM there are : * Resistent to Fading = Reduces the complexity of the equalization process required on the receiver to compensate for the flat fading * Supports various Operating Modes = Adaptive Modulation, Adaptive Coding, Mimo, Duplex Mode * Easier to sync frequency and time * Simplify Channel Equalization ![](https://i.imgur.com/G8SIIic.png) <center>OFDM Transmitter</center> ![](https://i.imgur.com/yMMwwR6.png) <center>OFDM Receiver</center> In the OFDM system, the arrangement of several OFDM symbols forms a single OFDM Frame. In general, there are two types of frames, namely Uplink Frame OFDM and Downlink Frame OFDM. Uplink is a communication line from the Subscriber Station (SS) to the Base Station (BS). On the other hand, Downlink is a communication path from BS to SS. Modulation is the process of changing a periodic wave with a certain frequency in order to be able to carry information. Demodulation is the process of returning the bit value of the modulated signal y which consists of Real (I) and Imaginary (Q) components received. The modulation-demodulation process is also known as Mapper-Demapper, which is the mapping of binary samples to complex number samples and vice versa (bit symbol). ### Comment OFDM and OFDMA are used in 5G O-RAN. It is a form of digital modulation and demodulation. ## <center> **Discussion with team** </center> :::info ### 1. Research About Sub-topics ### 2. Discuss About Next Meeting :::