Virtual Labs

Study of Frequency division multiplexed schemes

1. What is the primary advantage of using OFDM in high-speed wireless communication systems?

a: Increased latency and complexity Explanation

Explanation

b: Improved resistance to multipath fading and interference Explanation

Explanation

c: Higher signal power requirement Explanation

Explanation

d: Reduced bandwidth utilization Explanation

Explanation

2. In the context of OFDM, what is the significance of the cyclic prefix?

a: It increases the data rate. Explanation

Explanation

b: It allows for frequency synchronization. Explanation

Explanation

c: It serves as a guard interval to mitigate inter-symbol interference. Explanation

Explanation

d: It reduces the overall bandwidth of the signal. Explanation

Explanation

3. What is the role of the Fast Fourier Transform (FFT) in the OFDM receiver?

a: It modulates the signal for transmission. Explanation

Explanation

b: It converts the time-domain signal back to frequency-domain for demodulation. Explanation

Explanation

c: It generates the original signal for decoding. Explanation

Explanation

d: It equalizes the received signal. Explanation

Explanation

4. In an OFDM system, how does subcarrier spacing affect performance?

a: Wider subcarrier spacing increases the risk of inter-carrier interference. Explanation

Explanation

b: Narrower subcarrier spacing reduces bandwidth efficiency. Explanation

Explanation

c: Wider subcarrier spacing allows for better frequency diversity. Explanation

Explanation

d: Narrower subcarrier spacing improves resistance to frequency-selective fading. Explanation

Explanation

5. Which modulation scheme is often used in conjunction with OFDM to achieve high data rates?

a: QPSK (Quadrature Phase Shift Keying) Explanation

Explanation

b: 16-QAM (Quadrature Amplitude Modulation) Explanation

Explanation

c: FSK (Frequency Shift Keying) Explanation

Explanation

d: PSK (Phase Shift Keying) Explanation

Explanation

6. What is the effect of increasing the number of subcarriers in an OFDM system?

a: Decreased data throughput due to increased overhead. Explanation

Explanation

b: Increased resilience to frequency-selective fading. Explanation

Explanation

c: Higher complexity in the transmitter design. Explanation

Explanation

d: Lower overall spectral efficiency. Explanation

Explanation

7. How does OFDM mitigate the effects of multipath fading?

a: By using a single high-frequency carrier. Explanation

Explanation

b: By transmitting multiple signals simultaneously over different frequencies. Explanation

Explanation

c: By dividing the signal into multiple orthogonal subcarriers. Explanation

Explanation

d: By employing spread spectrum techniques. Explanation

Explanation

8. What is one major challenge when implementing OFDM systems?

a: The need for precise synchronization between transmitter and receiver. Explanation

Explanation

b: The simplicity of the modulation scheme. Explanation

Explanation

c: The requirement for low bandwidth. Explanation

Explanation

d: The inability to support high data rates. Explanation

Explanation

9. What is the impact of using a longer cyclic prefix in OFDM?

a: It increases the data rate. Explanation

Explanation

b: It reduces inter-symbol interference but decreases the overall data throughput. Explanation

Explanation

c: It enhances the frequency diversity of the subcarriers. Explanation

Explanation

d: It simplifies the receiver design. Explanation

Explanation

10. In OFDM, what is meant by 'spectral efficiency'?

a: The amount of data transmitted per unit of bandwidth. Explanation

Explanation

b: The total power used in transmission. Explanation

Explanation

c: The time taken to transmit a given amount of data. Explanation

Explanation

d: The ability to resist noise in the communication channel. Explanation

Explanation