RF Engineering

# RF Engineering Day 4: July 22th, 2021 ###### tags: `PNJ` `5G O-RAN` `ITB NTUST 5G course` :::success ### 3 Most Important Aspects 1. Wireless Channel Modelling 2. Introduction to GNU Octave 3. Analysis theory in Channel Modelling ::: :::info ### Summary Channel Model is t is mathematical technique to describe the behavior (characteristics) of channel. 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. The signal characteristics are due to several phenomena: 1) existence of line of sight path between the antennas, 2) reflection, refraction and diffraction of the signal due to the objects in between the antennas, 3) The relative motion between the transmitter and receiver and the objects in between them, 4) The signal attenuation as it travels through the medium, 5) Noise The received signal can be obtained from the transmitter signal if we can accurately model the channel in between the antennas. Consider a channel with impulse response h(t) between the transmitter and receiver antenna. In addition to the channel impulse response, the transmitted signal x(t) is also corrupted by the additive noise component n(t). The received signal y(t) is obtained by the convolution of h(t) and x(t) added with the noise component z(t). y(t) = h(t) * x(t) + z(t) GNU Octave is software featuring a high-level programming language, primarily intended for numerical computations. Octave helps in solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with 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. ::: :::info ### Comment Each channel has its own behavior, therefore, we must know the various characteristics of the channel so that each problem can be handled properly. For solving linear and nonlinear problems numerically, and for performing other numerical experiments we can use GNU Octave software. :::