Which access method is used by GSM where multiple devices share a channel in time slots?

Which access method is used by GSM where multiple devices share a channel in time slots?

• A. Space Division Multiple Access
• B. Code Division Multiple Access
• C. Time Division Multiple Access
• D. Frequency Division Multiple Access

Answer: (C)

The concept here is dividing a single radio channel in time to let multiple devices share it. In TDMA, the same frequency channel is split into time slots, and each user gets a specific slot to transmit. In GSM, a given carrier frequency is divided into eight time slots that repeat in a frame, so up to eight users can share that channel by transmitting in their assigned slots. This time-based separation is what makes TDMA distinct. Other access methods separate users by different means: SDMA uses spatial separation (different directions or antennas), CDMA uses unique codes to distinguish users over the same time and frequency, and FDMA allocates different frequencies to different users. In GSM, the combination is FDMA at the carrier level with TDMA inside each carrier, but the question focuses on the time-slot sharing, which is TDMA.

The concept here is dividing a single radio channel in time to let multiple devices share it. In TDMA, the same frequency channel is split into time slots, and each user gets a specific slot to transmit. In GSM, a given carrier frequency is divided into eight time slots that repeat in a frame, so up to eight users can share that channel by transmitting in their assigned slots. This time-based separation is what makes TDMA distinct.

Other access methods separate users by different means: SDMA uses spatial separation (different directions or antennas), CDMA uses unique codes to distinguish users over the same time and frequency, and FDMA allocates different frequencies to different users. In GSM, the combination is FDMA at the carrier level with TDMA inside each carrier, but the question focuses on the time-slot sharing, which is TDMA.