In WLAN network, there are four transmission systems: SISO, MISO, SIMO and MIMO. Which of the four transmission systems can transmit two signals at the same time?

Question

Options

• ASIMO
• BSIso
• CMISO
• DMIMO

• A
  3% (1)
• B
  6% (2)
• C
  9% (3)
• D
  82% (27)

Explanation

MIMO (Multiple Input, Multiple Output) is the only system capable of transmitting two signals simultaneously because it uses multiple antennas at both the transmitter and receiver, enabling spatial multiplexing - sending independent data streams over the same channel at the same time.

Why the distractors are wrong:

• SISO (Single Input, Single Output) has just one transmit and one receive antenna, so only one signal path exists.
• SIMO (Single Input, Multiple Output) has one transmit antenna and multiple receive antennas - only one signal is sent, though multiple antennas capture it for better reception (diversity).
• MISO (Multiple Input, Single Output) has multiple transmit antennas but only one receive antenna, so the receiver cannot separate simultaneous streams; it's used for transmit diversity or beamforming, not multiplexing.

Memory tip: Focus on the number of antennas on both sides. Only MIMO has "Multiple" on both ends - and you need multiple antennas at the receiver to separate simultaneous signals. Think: "MIMO = More In, More Out = More streams."

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