# <center> **Daily Report 4** </center>
###### tags: `O-RAN` `IVC` `5G O-RAN` `ITB NTUST 5G course`
> Date: 22/07
## <center> **RF Engineering** </center>

### **Important Aspects**
#### **1. Channel Modelling**
#### **2. Introduction to Octave**
#### **3. Analysis theory in Channel Modelling**

### **Summary**
Channel model is Characteristic modelling of the transmission media when a wireless signal propagates in the air from the transmitter to te receiver, it will change depending on various conditions, such as distance, trajectory, number of path, environmental condition an so on. There are several wireless channels in digital communication systems, such as propagation channel, radio channel, modulation channel, digital channel. Communication systems convert information into a format appropriate for the transmission medium. Analog communication systems convert (modulate) analog signals into modulated (analog) signals – amplification to extend distance – noise grows linearly. Digital communication systems convert information in the form of bits into binary/digital signal – bit regeneration to extend distance – BER groes, but slowly. There are many cases in channel modelling such as Noise, Multipath Channel (Reflection Difraction, Scattering), Interference, Delay, Path Loss, Shadowing, Fading. The received signal y(t) can be defined as the result of the convolution between the transmitted signal x(t) and the channel response impulse h(t) plus the noise z(t).
<center> y(t) = h(t) * x(t) + z(t) </center>
<p>In the freq domain:</p>
<center> Y(n) = H(n) . X(n) + Z(n) </center>

Octave is free software designed for scientific computing. It is used to solve linear equations and to work with matrices and vector. Octave is similar to the Matlab. Need to install Communication package to do Digital Communications, Error Correcting Codes (Channel Code), Source Code functions, Modulation and Galois Fields. Additive White Gaussian Noise (AWGN) is caused by various factors, such as thermal noise, shot noise, black body radiation from the earth and other warm objects, as well as the influence of space objects such as solar radiation. The Rayleigh distribution is used to describe the statistics of the super positioned signal from the overall reflection or diffraction signal due to the multipath path. The Rician distribution is used to describe conditions when the received signal contains a Line-of-Sight (LOS) signal component. Frequency shift is called frequency offset. The initial detection error of the frame is called time offset. The IQ imbalance is caused by the difference in gain and phase on the I arm and the Q arm on the RF modulator or demodulator.

### Comment
Radio-frequency (RF) engineering cover the application of transmission line, waveguide, antenna and electromagnetic field.

## <center> **Discussion with team** </center>
:::info
### 1. Discuss About Division For Sub-topics
### 2. Discuss About Final Project
### 3. Discuss About Next Meeting
:::