Multiple Access Schemes are methods that let multiple devices share a communication channel without collisions.
They ensure fair and efficient use of the channel.
- FDMA (Frequency Division Multiple Access): Users get separate frequencies. Like radio stations on different channels.
- TDMA (Time Division Multiple Access): Users take turns in time slots. Like people talking on a conference call.
- CDMA (Code Division Multiple Access): Users send data with unique codes. Like people talking in different languages.
These schemes manage how users share a channel to transmit and receive data without interfering with each other.
Comparison between FDMA and TDMA
|Basic Concept||Divides frequency spectrum into non-overlapping frequency bands for users.||Divides time into discrete slots for users.|
|Interference||Interference occurs if signals overlap in frequency.||Interference occurs if signals overlap in time.|
|Resource Allocation||Each user gets a fixed frequency band.||Users share the same frequency band but take turns using it.|
|Efficiency||Bandwidth can be unused if traffic is low for some users.||Efficient for bursty traffic, as users transmit only in their allocated time slots.|
|Complexity||Requires precise frequency control to avoid overlap.||Requires synchronization to allocate time slots correctly.|
|Examples||Cellular networks (different channels for users).||GSM (Global System for Mobile Communications) – users share channels with time slots.|
|Analogous Scenario||Different radio stations on separate frequencies.||People taking turns speaking in a conference call.|
|Advantages||Simple frequency allocation, suitable for voice communication.||Efficient use of bandwidth, adaptable to changing traffic.|
|Disadvantages||Inefficient for bursty data, limited users per frequency band.||Requires synchronization, complex in high-mobility scenarios.|