FDMA, or Frequency Division Multiple Access, is a channel access method where different users are assigned to non-overlapping frequency bands to communicate simultaneously. It's a basic technique used in early cellular systems.
Here's a more detailed breakdown:
-
Concept: FDMA divides the available frequency spectrum into smaller, distinct channels. Each user is allocated a specific frequency channel for the duration of their communication.
-
How it works:
- The total available bandwidth is divided into multiple frequency channels.
- Each channel is assigned to a different user.
- Users transmit and receive data within their allocated frequency band.
- Guard bands (small unused frequency ranges) are implemented between adjacent channels to prevent interference.
-
Example: Imagine a radio station with multiple channels. Each channel broadcasts on a different frequency, allowing listeners to tune into different stations without interference. Similarly, in FDMA, each user gets their "radio channel" to communicate.
-
Advantages:
- Simple to implement, especially in early systems.
- Allows continuous transmission, unlike some other access methods.
-
Disadvantages:
- Can be inefficient in bandwidth utilization, as some channels might be underutilized while others are overloaded.
- Susceptible to intermodulation distortion if power amplifiers are not linear.
- Fixed channel allocation can be inflexible and unable to adapt to varying traffic demands.
-
Use Cases: FDMA was primarily used in first-generation (1G) and second-generation (2G) cellular systems. However, it has been largely superseded by more efficient technologies like TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access) in modern wireless communication systems, although variations and combinations of FDMA still exist.
In summary, FDMA is a channel access method where the available frequency spectrum is divided into channels and assigned to different users, providing them with dedicated bandwidth for communication.
