Skip to main content
Home Wireless Communication Modulation MATLAB Beamforming Project Ideas MIMO Computer Networks Lab 🚀
Electronics Industry Wireless FORUM Work Hub Applications & Games Generate QR for Any Link Sitemap Generator (for Any Website) Play game Electrical & Electronics Calculator Contact Get Newsletter.
☰

Impact of Rayleigh Fading and AWGN on Digital Communication Systems

 

Digital Communication with Channel Equalization and Demodulation: Overcoming Rayleigh Fading and AWGN

Digital communication system with channel equalization and demodulation involves transmitting a modulated signal through a channel affected by Rayleigh fading and AWGN. Equalization mitigates signal distortion, and demodulation extracts the original message signal, ensuring reliable data recovery.

Understanding the digital communication process involves several key stages. Each stage is crucial for ensuring that the message signal is transmitted effectively and accurately. Below is a detailed overview of each stage in the process:

  1. Message Signal: This is the original data or information that needs to be transmitted from the sender to the receiver. It can be in the form of text, audio, video, or any other type of data. The message signal is the input to the communication system, representing the content that the sender wants to convey. 
     
    Fig: Original Message Signal
     

     Fig: Carrier Signal

  2. Modulation: To prepare the message signal for transmission over a communication channel, it must be modulated onto a carrier signal. Modulation involves varying the carrier signal's properties (such as amplitude, frequency, or phase) in accordance with the message signal. This process helps in effectively transmitting the signal over long distances and through various mediums. Common modulation techniques include Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM).
     
     

  3. Channel (with Rayleigh Fading and AWGN): The modulated signal is transmitted through a communication channel, which may introduce various impairments:
    • Rayleigh Fading: This occurs due to multipath propagation, where the transmitted signal reflects off various objects and surfaces before reaching the receiver. These reflections can cause interference, leading to fluctuations in signal strength and quality. Rayleigh fading is particularly significant in mobile communications and environments with many reflective surfaces.
       
       

    • AWGN (Additive White Gaussian Noise): This is random noise that adds to the signal during transmission. AWGN is characterized by its white (uniform across frequencies) and Gaussian (normal distribution) nature. It affects the signal by introducing randomness and reducing the signal-to-noise ratio (SNR), which can degrade the quality of the received signal.
       
       

  4. Received Signal: After passing through the channel, the signal received by the receiver is a combination of the original modulated signal, Rayleigh fading effects, and AWGN. This signal may be distorted and weakened compared to the original transmitted signal, making it necessary to apply further processing to recover the original message.
     
     
     
     
    Bit error rate due to Rayleigh fading and AWGN noise is...
     0.16
                Where is the bit error rate due to only AWGN noise is    0.078 (for BPSK modulation at 0 dB SNR)
  5. Equalization: To address the distortions caused by Rayleigh fading and other channel impairments, equalization techniques are used. Equalization aims to reverse the effects of distortion and restore the signal to its intended form. It involves adjusting the signal to compensate for the channel’s impairments and improve the overall quality and reliability of the received signal. Various equalization techniques include linear equalizers, decision feedback equalizers, and adaptive equalizers.
  6. Demodulation: Once the signal has been equalized, demodulation is performed to extract the original message signal from the modulated carrier signal. Demodulation reverses the modulation process, removing the carrier signal and recovering the original data. This stage is critical for retrieving the information that was transmitted over the communication channel.
  7. Message Signal Recovery: After demodulation, the original message signal is recovered. This stage represents the successful completion of the communication process, where the transmitted data is accurately retrieved and can be used by the receiver. The quality of the recovered message signal depends on the effectiveness of the modulation, channel equalization, and demodulation processes.

People are good at skipping over material they already know!

View Related Topics to







Admin & Author: Salim

profile

  Website: www.salimwireless.com
  Interests: Signal Processing, Telecommunication, 5G Technology, Present & Future Wireless Technologies, Digital Signal Processing, Computer Networks, Millimeter Wave Band Channel, Web Development
  Seeking an opportunity in the Teaching or Electronics & Telecommunication domains.
  Possess M.Tech in Electronic Communication Systems.


Contact Us

Name

Email *

Message *

Popular Posts

Rayleigh vs Rician Fading

  In Rayleigh fading, the channel coefficients tend to have a Rayleigh distribution, which is characterized by a random phase and magnitude with an exponential distribution. This means the magnitude of the channel coefficient follows an exponential distribution with a mean of 1. In Rician fading, there is a dominant line-of-sight component in addition to the scattered components. The channel coefficients in Rician fading can indeed tend towards 1, especially when the line-of-sight component is strong. When the line-of-sight component dominates, the Rician fading channel behaves more deterministically, and the channel coefficients may tend towards the value of the line-of-sight component, which could be close to 1.   MATLAB Script clc; clear all; close all; % Define parameters numSamples = 1000; % Number of samples K_factor = 5; % K-factor for Rician fading SNR_dB = 20; % Signal-to-noise ratio (in dB) % Generate complex Gaussian random variable for Rayleigh fading channel h_rayleigh = (
Read more

MATLAB code for BER vs SNR for M-QAM, M-PSK, QPSk, BPSK, ...

Modulation Constellation Diagrams BER vs. SNR MATLAB code for BER vs SNR for M-QAM, M-PSK, QPSk, BPSK, ...   MATLAB Script for  BER vs. SNR for M-QAM, M-PSK, QPSk, BPSK %Written by Salim Wireless %Visit www.salimwireless.com for study materials on wireless communication %or, if you want to learn how to code in MATLAB clc; clear; close all; % Parameters num_symbols = 1e5; % Number of symbols snr_db = -20:2:20; % Range of SNR values in dB % PSK orders to be tested psk_orders = [2, 4, 8, 16, 32]; % QAM orders to be tested qam_orders = [4, 16, 64, 256]; % Initialize BER arrays ber_psk_results = zeros(length(psk_orders), length(snr_db)); ber_qam_results = zeros(length(qam_orders), length(snr_db)); % BER calculation for each PSK order and SNR value for i = 1:length(psk_orders) psk_order = psk_orders(i); for j = 1:length(snr_db) % Generate random symbols data_symbols = randi([0, psk_order-1]
Read more

Comparisons among ASK, PSK, and FSK | And the definitions of each

Modulation ASK, FSK & PSK Constellation MATLAB Simulink MATLAB Code Comparisons among ASK, PSK, and FSK    Comparisons among ASK, PSK, and FSK Comparison among ASK,  FSK, and PSK Performance Comparison: 1. Noise Sensitivity:    - ASK is the most sensitive to noise due to its reliance on amplitude variations.    - PSK is less sensitive to noise compared to ASK.    - FSK is relatively more robust against noise, making it suitable for noisy environments. 2. Bandwidth Efficiency:    - PSK is the most bandwidth-efficient, requiring less bandwidth than FSK for the same data rate.    - FSK requires wider bandwidth compared to PSK.    - ASK's bandwidth efficiency lies between FSK and PSK. Bandwidth Calculator for ASK, FSK, and PSK The baud rate represents the number of symbols transmitted per second Select Modulation Type: ASK FSK PSK Baud Rate (Hz):
Read more

BER vs SNR for M-ary QAM, M-ary PSK, QPSK, BPSK, ...

Modulation Constellation Diagrams BER vs. SNR BER vs SNR for M-QAM, M-PSK, QPSk, BPSK, ... 1. What is Bit Error Rate (BER)? The abbreviation BER stands for bit error rate, which indicates how many corrupted bits are received (after the demodulation process) compared to the total number of bits sent in a communication process. It is defined as,  In mathematics, BER = (number of bits received in error / total number of transmitted bits)  On the other hand, SNR refers to the signal-to-noise power ratio. For ease of calculation, we commonly convert it to dB or decibels.   2. What is Signal the signal-to-noise ratio (SNR)? SNR = signal power/noise power (SNR is a ratio of signal power to noise power) SNR (in dB) = 10*log(signal power / noise power) [base 10] For instance, the SNR for a given communication system is 3dB. So, SNR (in ratio) = 10^{SNR (in dB) / 10} = 2 Therefore, in this instance, the signal power i
Read more

Constellation Diagrams of ASK, PSK, and FSK

Modulation ASK, FSK & PSK Constellation BASK (Binary ASK) Modulation: Transmits one of two signals: 0 or -√Eb, where Eb​ is the energy per bit. These signals represent binary 0 and 1.  BFSK (Binary FSK) Modulation: Transmits one of two signals: +√Eb​ ( On the y-axis, the phase shift of 90 degrees with respect to the x-axis, which is also termed phase offset ) or √Eb (on x-axis), where Eb​ is the energy per bit. These signals represent binary 0 and 1.  BPSK (Binary PSK) Modulation: Transmits one of two signals: +√Eb​ or -√Eb (they differ by 180 degree phase shift), where Eb​ is the energy per bit. These signals represent binary 0 and 1.  This article will primarily discuss constellation diagrams, as well as what constellation diagrams tell us and the significance of constellation diagrams. Constellation diagrams can often demonstrate how the amplitude and phase of signals or symbols differ. These two characteristics lessen the interference between t
Read more

Simulation of ASK, FSK, and PSK using MATLAB Simulink

ASK, FSK & PSK HomePage MATLAB Simulation Simulation of Amplitude Shift Keying (ASK) using MATLAB Simulink      In Simulink, we pick different components/elements from MATLAB Simulink Library. Then we connect the components and perform a particular operation.  Result A sine wave source, a pulse generator, a product block, a mux, and a scope are shown in the diagram above. The pulse generator generates the '1' and '0' bit sequences. Sine wave sources produce a specific amplitude and frequency. The scope displays the modulated signal as well as the original bit sequence created by the pulse generator. Mux is a tool for displaying both modulated and unmodulated signals at the same time. The result section shows that binary '1' is modulated by a certain sine wave amplitude of 1 Volt, and binary '0' is modulated by zero amplitude. Simulation of Frequency Shift Keying (FSK) using MATLAB Simulink   Result The diagram above shows t
Read more

Channel Impulse Response (CIR)

Channel Impulse Response (CIR) Wireless Signal Processing CIR, Doppler Shift & Gaussian Random Variable  The Channel Impulse Response (CIR) is a concept primarily used in the field of telecommunications and signal processing. It provides information about how a communication channel responds to an impulse signal.   What is the Channel Impulse Response (CIR) ? It describes the behavior of a communication channel in response to an impulse signal. In signal processing,  an impulse signal has zero amplitude at all other times and amplitude  ∞ at time 0 for the signal. Using a Dirac Delta function, we can approximate this.  ...(i) δ( t) now has a very intriguing characteristic. The answer is 1 when the Fourier Transform of  δ( t) is calculated. As a result, all frequencies are responded to equally by  δ (t). This is crucial since we never know which frequencies a system will affect when examining an unidentified one. Since it can test the system for all freq
Read more

How to use MATLAB Simulink

  MATLAB Simulink is a popular add-on of MATLAB. Here, you can use different blocks like modulator, demodulator, AWGN channel, etc. And you can do experiments on your own.       Steps Go to the 'Simulink' tab at the top navbar of MATLAB. If not found, click on the add-on tab, search 'Simulink,' and then click on it to add. Once you installed the simulation, click the 'new' tap at the top left corner. Then, search the required blocks in the 'Simulink library.' Then, drag it to the editor space. You can double-click on the blocks to see the input parameters Then, connect the blocks by dragging a line from one block's output terminal to another block's input. If the connection is complete, click the 'run' tab in the middle of the top navbar.   After clicking on the run button, your Simulink is ready. Then double-click on any block to see the output   The following block diagram is an example of the MATLAB simulation of 'QPSK'
Read more
document.onmouseup=new Function ("return false"); }