Wireless Communication Techniques Quiz

In a school project, Krish, Nikita, and Avni are assigned different frequency bands to communicate with their respective teams. Which multiple access technique assigns a unique frequency band to each user?

• TDMA

• FDMA

• CDMA

• SDMA

Answer explanation

FDMA (Frequency Division Multiple Access) assigns a unique frequency band to each user, allowing them to communicate simultaneously without interference. This is the correct choice for the scenario described.

Aarush, Aditi, and Krish are participating in a timed quiz competition where each participant gets a specific time slot to answer their questions. This method of organizing the quiz ensures that each participant has their own time to respond without interference from others. This method of separation is known as:

• Frequency

• Code

• Time

• Power

Answer explanation

The method of organizing the quiz where each participant has their own time slot to respond is known as 'Time'. This ensures that responses are given without interference, highlighting the importance of time management in the competition.

Which multiple access technique employs unique spreading sequences to enable simultaneous communication for various users?

• TDMA

• FDMA

• CDMA

• OFDMA

Answer explanation

CDMA (Code Division Multiple Access) uses unique spreading sequences for each user, allowing multiple users to communicate simultaneously over the same frequency band without interference, making it the correct choice.

OFDMA is primarily used in which generation of wireless networks?

• 2G

• 3G

• 4G

• 1G

Answer explanation

OFDMA (Orthogonal Frequency Division Multiple Access) is a key technology used in 4G wireless networks, enabling efficient data transmission and improved capacity compared to earlier generations like 2G and 3G.

What is the main limitation of FDMA?

• High latency

• Time synchronization required

• Guard bands reduce efficiency

• Complex decoding

Answer explanation

The main limitation of FDMA is that guard bands are required to prevent interference between channels. These guard bands reduce the overall efficiency of the frequency spectrum, making it less optimal compared to other multiple access techniques.

Which technique offers soft handoff in mobile communication?

• TDMA

• CDMA

• FDMA

• OFDMA

Answer explanation

CDMA (Code Division Multiple Access) allows for soft handoff, enabling a mobile device to connect to multiple cell towers simultaneously, improving call quality and reducing dropped calls during transitions.

In which technique is the ‘near-far’ problem commonly observed?

• TDMA

• FDMA

• CDMA

• SDMA

Answer explanation

The ‘near-far’ problem is commonly observed in CDMA (Code Division Multiple Access) systems, where signals from nearby users can interfere with those from users farther away, affecting communication quality.

Which of the following techniques uses orthogonal subcarriers?

• CDMA

• NOMA

• OFDMA

• FDMA

Answer explanation

OFDMA (Orthogonal Frequency Division Multiple Access) uses orthogonal subcarriers to allow multiple users to share the same frequency band without interference, making it efficient for high data rate transmissions.

Which access technique utilizes spatial separation with smart antennas?

• FDMA

• SDMA

• TDMA

• NOMA

Answer explanation

SDMA (Space Division Multiple Access) uses spatial separation with smart antennas to allow multiple users to share the same frequency by distinguishing their signals based on their physical location.

NOMA differentiates users primarily by:

• Frequency

• Code

• Time

• Power level

Answer explanation

NOMA (Non-Orthogonal Multiple Access) primarily differentiates users by power level, allowing multiple users to share the same frequency and time resources by assigning different power levels to their signals.