Which of the following systems uses TDMA for its operations?

The system that operates using Time Division Multiple Access (TDMA) is GSM, which stands for Global System for Mobile Communications. TDMA is a technique that allows multiple users to share the same frequency channel by assigning unique time slots to each user within the channel. This means that each user transmits in their allocated time slots, effectively managing user access to the channel and reducing interference among users.

GSM specifically utilizes TDMA in its operation to allow multiple calls to coexist on the same frequency band without causing interference. It segments the available frequency into time slots for different calls, making it an efficient way to utilize limited spectrum resources while ensuring that voice and data services can operate simultaneously.

The other options employ different access methods. CDMA (Code Division Multiple Access) uses spread-spectrum technology, allowing multiple users to share the same frequency band simultaneously but distinguishes users by unique spreading codes. Bluetooth uses a frequency-hopping spread spectrum, allowing devices to communicate with each other over short distances. WLAN (Wireless Local Area Network) typically utilizes a technique called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) to share the medium among devices in a network. Understanding these distinctions clarifies why GSM is the correct choice for a system that utilizes TDMA.