Skip to main content

Comparison of FDMA, TDMA, & CDMA | Methods of Transmitting and Receiving ...




Two key modulation techniques utilized in 2G GSM are TDM and FDM. The advantages of modulation techniques have already been explored. TDM and FDM allow several data streams to pass through the channel between transmitter and receiver at the same time. We can figure out what they are based on their names. For example, each GSM channel has a bandwidth of 200 KHz. Furthermore, a single channel can connect up to eight users at the same time.
 

1. FDMA:


Frequency division multiplexing access (FDMA) is an acronym for frequency division multiplexing. The entire available bandwidth is subdivided into several sections using this strategy. Each sub band is assigned to a certain device. It's also feasible to apply TDMA on each of the sub bands separately.
 

2. TDMA:


Time division multiplexing access (TDMA) is an acronym for time division multiplexing. TDMA is a modulation technology that allows us to connect many devices to a base station or access point by providing them distinct time slots. We use a rotator in TDMA to establish distinct time slots, and then we use TDMA to link multiple devices. For example, each 2G GSM channel has a bandwidth of 200 KHz, and we connect eight users using TDMA or various time slots.
 

3. CDMA:[↗]

Code division multiplexing access (CDMA) is the abbreviation for code division multiplexing access. 3G technology was the first to use this strategy. Different forms of coding are used in code division multiplexing access. So, the term "CDMA" can refer to a variety of communication protocols. The fundamental idea is to give each mobile phone a special code. These codes are all mutually orthogonal to one another. For example, a base station (BS) emits a code, which many devices attempt to decode. The signal will only be received by the intended user; it will be discarded by others. Simply put, we can say that there is a conference room and that there are numerous individuals speaking different languages in it. Now that one of the speakers is speaking Chinese, only those who are familiar with the language will be able to understand. A person who does not speak Chinese will be unable to comprehend a single word. The same thing happens when users or linked devices have access to code division multiplexing.

Each user in this scenario has access to the full frequency band and is free to transmit at any moment. In comparison to FDMA and TDMA, CDMA is hence more flexible. Other CDMA plans make advantage of system resources to provide multiple channels.

Spread spectrum techniques include the frequency-hopping CDMA technology. Pseudorandom (PN) codes assigned to each user are used to modulate the signal that will be broadcast. This is comparable to FDMA because each user will be transmitting at a separate frequency as a result. As the PN code evolves, the user will eventually be broadcasting over a different carrier frequency for each time slot, which is akin to TDMA.
[Click here to read about CDMA in details]

4. Comparison of TDMA & FDMA:


1.In FDM, you can transmit and receive in different bands at the same time.


2.In TDM, transmission and reception take place on the same frequency range, but at different times.


3.For FDM, guard frequency bands are necessary, resulting in system overhead.


4.Spectral inefficiency is required for TDM guard time slots.


5.TDM outperforms FDM in terms of noise resistance.




We can conclude from the three multiplexing techniques mentioned above that we can send multiple data streams utilizing those multiplexing techniques over a single signal path / route. It is also clear that while using the same transmission line, desired users can access independent signals.


5. Advantages of CDMA Technique over FDMA and TDMA

The use of a CDMA system has some key benefits. There may be excessive multipath propagation when signals are sent across a random medium. This phenomenon results in small-scale fading. A frequency selective channel is one sort of fading channel that attenuates some frequencies more than others. Because of this, received signal strength inside this kind of channel can fluctuate significantly. 

A user in a poor frequency band will only use that band for a brief amount of time in an FH-CDMA scheme. Therefore, CDMA systems can aid in combating fading channels. It is a benefit of a CDMA

Another advantage to a CDMA code is the privacy that it can afford a user. Any receiver can pick up the same signal that a user is transmitting and receiving when the user has a stable frequency band.


Read more about

[1] Click here to read about CDMA in details

People are good at skipping over material they already know!

View Related Topics to







Admin & Author: Salim

s

  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

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

📘 Overview of BER and SNR 🧮 Online Simulator for BER calculation of m-ary QAM and m-ary PSK 🧮 MATLAB Code for BER calculation of M-ary QAM, M-ary PSK, QPSK, BPSK, ... 📚 Further Reading 📂 View Other Topics on M-ary QAM, M-ary PSK, QPSK ... 🧮 Online Simulator for Constellation Diagram of m-ary QAM 🧮 Online Simulator for Constellation Diagram of m-ary PSK 🧮 MATLAB Code for BER calculation of ASK, FSK, and PSK 🧮 MATLAB Code for BER calculation of Alamouti Scheme 🧮 Different approaches to calculate BER vs SNR 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 ...

Comparing Baseband and Passband Implementations of ASK, FSK, and PSK

📘 Overview 🧮 Baseband and Passband Implementations of ASK, FSK, and PSK 🧮 Difference betwen baseband and passband 📚 Further Reading 📂 Other Topics on Baseband and Passband ... 🧮 Baseband modulation techniques 🧮 Passband modulation techniques   Baseband modulation techniques are methods used to encode information signals onto a baseband signal (a signal with frequencies close to zero), allowing for efficient transmission over a communication channel. These techniques are fundamental in various communication systems, including wired and wireless communication. Here are some common baseband modulation techniques: Amplitude Shift Keying (ASK) [↗] : In ASK, the amplitude of the baseband signal is varied to represent different symbols. Binary ASK (BASK) is a common implementation where two different amplitudes represent binary values (0 and 1). ASK is simple but susceptible to noise...

Constellation Diagrams of ASK, PSK, and FSK

📘 Overview of Energy per Bit (Eb / N0) 🧮 Online Simulator for constellation diagrams of ASK, FSK, and PSK 🧮 Theory behind Constellation Diagrams of ASK, FSK, and PSK 🧮 MATLAB Codes for Constellation Diagrams of ASK, FSK, and PSK 📚 Further Reading 📂 Other Topics on Constellation Diagrams of ASK, PSK, and FSK ... 🧮 Simulator for constellation diagrams of m-ary PSK 🧮 Simulator for constellation diagrams of m-ary QAM 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...

MATLAB Code for Pulse Amplitude Modulation (PAM) and Demodulation

📘 Overview & Theory of Pulse Amplitude Moduation (PAM) 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of Analog Signal and Digital Signal 🧮 Simulation results for comparison of PAM, PWM, PPM, DM, and PCM 📚 Further Reading 📂 Other Topics on Pulse Amplitude Modulation ... 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of an Analog Signal (2) 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of Digital data 🧮 Other Pulse Modulation Techniques (e.g., PWM, PPM, DM, and PCM)   Pulse Amplitude Modulation (PAM) & Demodulation of an Analog Message Signal MATLAB Script clc; clear all; close all; fm= 10; % frequency of the message signal fc= 100; % frequency of the carrier signal fs=1000*fm; % (=100KHz) sampling frequency (where 1000 is the upsampling factor) t=0:1/fs:1; % sampling rate of (1/fs = 100 kHz) m=1*cos(2*pi*fm*t); % Message signal with per...

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

📘 Comparisons among ASK, FSK, and PSK 🧮 Online Simulator for calculating Bandwidth of ASK, FSK, and PSK 🧮 MATLAB Code for BER vs. SNR Analysis of ASK, FSK, and PSK 📚 Further Reading 📂 View Other Topics on Comparisons among ASK, PSK, and FSK ... 🧮 Comparisons of Noise Sensitivity, Bandwidth, Complexity, etc. 🧮 MATLAB Code for Constellation Diagrams of ASK, FSK, and PSK 🧮 Online Simulator for ASK, FSK, and PSK Generation 🧮 Online Simulator for ASK, FSK, and PSK Constellation 🧮 Some Questions and Answers Modulation ASK, FSK & PSK Constellation MATLAB Simulink MATLAB Code Comparisons among ASK, PSK, and FSK    Comparisons among ASK, PSK, and FSK   Simulator for Calculating Bandwidth of ASK, FSK, and PSK The baud rate represents the number of symbols transmitted per second. Both baud rate and bit rate a...

Constellation Diagrams of M-ary QAM | M-ary Modulation

📘 Overview of QAM 🧮 MATLAB Code for m-ary QAM (4-QAM, 16-QAM, 32-QAM, ...) 🧮 Online Simulator for M-ary QAM Constellations 📚 Further Reading 📂 Other Topics on Constellation Diagrams of QAM configurations ... 🧮 MATLAB Code for 4-QAM 🧮 MATLAB Code for 16-QAM 🧮 MATLAB Code for m-ary QAM (4-QAM, 16-QAM, 32-QAM, ...) 🧮 Simulator for constellation diagrams of m-ary PSK 🧮 Simulator for constellation diagrams of m-ary QAM 🧮 Overview of Energy per Bit (Eb / N0) 🧮 Online Simulator for constellation diagrams of ASK, FSK, and PSK 🧮 Theory behind Constellation Diagrams of ASK, FSK, and PSK 🧮 MATLAB Codes for Constellation Diagrams of ASK, FSK, and PSK QAM Unlike this, the M-ary PSK signal is modulated with a different phase-shifted version of the carrier signal and varying amplitude levels. Let me give an example for better comprehension. QAM = ASK +...

Coherence Bandwidth and Coherence Time

🧮 Coherence Bandwidth 🧮 Coherence Time 🧮 Coherence Time Calculator 🧮 Relationship between Coherence Time and Delay Spread 🧮 MATLAB Code to find Relationship between Coherence Time and delay Spread 📚 Further Reading   Coherence Bandwidth Coherence bandwidth is a concept in wireless communication and signal processing that relates to the frequency range over which a wireless channel remains approximately constant in terms of its characteristics. coherence bandwidth is  The inverse of Doppler spread delay time, or any spread delay time due to fading in general.  The coherence bandwidth is related to the delay spread of the channel, which is a measure of the time it takes for signals to traverse the channel. The two are related by the following formulae: Coherence bandwidth = 1/(delay spread time) Or, Coherence Bandwidth = 1/(root-mean-square delay spread time) (Coherence bandwidth in Hertz) For instance, the coherence bandwidth is...

Definition of the Fourier Series

  1. Introduction Most of the phenomena studied in the domain of Engineering and Science are periodic in nature. For instance, current and voltage in an alternating current circuit. These periodic functions could be analyzed into their constituent components (fundamentals and harmonics) by a process called Fourier analysis. A Fourier series is an expansion of a periodic function into a sum of trigonometric functions. The Fourier series is an example of a trigonometric series, but not all trigonometric series are Fourier series. Fourier series is used to describe a periodic signal in terms of cosine and sine waves. In other words, it allows us to model any arbitrary periodic signal with a combination of sines and cosines.      Fig: Sine Wave       Fig: Triangular Wave    Fig: Sawtooth Wave      Fig: Square Wave   2. The common form of the Fourier series Sinusoidal functions are periodic over 2Ï€ angular distance. For a perio...