Difference Between FDMA and CDMA
Curated by
matthan
1 min read
137
FDMA (Frequency Division Multiple Access) and CDMA (Code Division Multiple Access) are two fundamental techniques used in wireless communication systems to allow multiple users to share the same communication channel. While both methods aim to maximize bandwidth efficiency, they employ distinctly different approaches to achieve this goal. FDMA divides the available frequency spectrum into separate channels for each user, whereas CDMA allows all users to transmit simultaneously across the entire frequency band using unique codes to distinguish individual signals.
FDMA vs CDMA Basics
FDMA operates by dividing the available frequency spectrum into distinct sub-channels, with each user assigned a dedicated frequency band for continuous transmission. In contrast, CDMA allows all users to transmit simultaneously across the entire frequency band, using unique pseudorandom noise codes to differentiate individual signals. This fundamental difference in approach impacts various aspects of their performance:
- FDMA requires guard bands between channels to prevent interference, while CDMA relies on code separation
- Synchronization is not necessary for FDMA, but CDMA may require time synchronization for optimal performance
- FDMA transmits data via continuous signals, whereas CDMA utilizes digital signals for transmission
3 sources
Bandwidth and Codeword Differences
Bandwidth allocation differs significantly between these two access methods. FDMA shares the available bandwidth among stations by dividing it into sub-channels, with each user assigned a dedicated frequency band. In contrast, CDMA allows all users to share both bandwidth and time simultaneously across the entire frequency spectrum. Another key distinction lies in the use of codewords. FDMA does not require any codeword for transmission, whereas CDMA necessitates a unique codeword for each user to differentiate their signals. This code-based approach enables CDMA to support multiple users on the same frequency band without interference, a feature not possible with FDMA's frequency-division method.
3 sources
Interference and Transmission Rates
A channel access method for multiple users to send data through a single communication channel
Description
FDMA is a channel access method that allows multiple users to send data through a single communication channel by dividing the channel's bandwidth into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user.
Implementation
Used in satellite communication systems and telephone trunklines
Bandwidth Allocation
Splits the total bandwidth into multiple channels, with each ground station allocated a particular frequency group or range of frequencies
Interference management differs significantly between the two systems. FDMA utilizes guard bands to prevent interference between adjacent channels, while CDMA relies on the orthogonality of codes to separate signals. This difference impacts transmission rates, with CDMA supporting higher data rates compared to FDMA's lower rates. Additionally, CDMA is more susceptible to the near-far problem, where stronger signals can overpower weaker ones, a challenge not present in FDMA systems.
3 sources
Flexibility and Capacity Comparison
Offering greater flexibility and capacity, CDMA outperforms FDMA in several key areas. The code-based system of CDMA allows for a higher number of simultaneous users and more efficient use of the available spectrum, resulting in a larger system capacity that is primarily limited by interference rather than channel availability. In contrast, FDMA's rigid frequency allocation scheme leads to a lower overall system capacity and less flexibility in accommodating varying user demands. This difference becomes particularly significant in high-traffic scenarios, where CDMA's ability to dynamically allocate resources provides a distinct advantage over FDMA's fixed channel assignments.
3 sources
Related
How does the flexibility of CDMA compare to that of FDMA and TDMA
What factors contribute to the higher capacity of CDMA systems
How does the power efficiency of FDMA compare to that of TDMA and CDMA
What are the main differences in implementation costs between FDMA and CDMA
How does the cell capacity of FDMA impact its practical applications
Keep Reading
FPGA vs. ASIC for AI: Which One Should You Choose?
In the rapidly evolving field of artificial intelligence (AI), selecting the right hardware is crucial for optimizing performance and efficiency. Field-Programmable Gate Arrays (FPGAs) and Application-Specific Integrated Circuits (ASICs) are two prominent types of hardware used in AI applications, each offering distinct advantages and facing unique limitations. This comparative analysis delves into the use cases, benefits, and challenges of FPGAs and ASICs, providing insights into their...
5,905
Rangefinders: Unmatched Golf Accuracy
When it comes to accurately measuring distances on the golf course, a rangefinder is the clear winner over GPS devices and smartphone apps. While GPS-based solutions offer convenience and course overviews, laser rangefinders provide unmatched precision, versatility, and the ability to measure distances to any target in sight, making them the top choice for serious golfers looking to improve their game.
4,512
All-Flash vs HDD: Evolving Tradeoffs
As data capacity is projected to grow tenfold by 2030, the shift toward all-flash storage systems presents a sustainable and economically viable solution compared to traditional hard disk drives (HDDs). All-flash arrays offer advantages in terms of scalability, reliability, power consumption, and total cost of ownership (TCO), making them an increasingly attractive option for future-proofing data storage in the rapidly evolving enterprise storage landscape.
1,476
The Rise of Car Paywalls
The automotive industry is undergoing a significant transformation with the rise of subscription-based features in vehicles. As reported by Autocar, major car manufacturers like Hyundai, BMW, Mercedes, and Audi are increasingly placing certain functionalities behind paywalls, sparking both interest and controversy among consumers.
25,475