Review Topics for Wireless Communication Midterm II

Multipath / Small Scale Fading (Ch4)

Doppler (5.1.2)

1. Be able to calculate expected Doppler shift for given frequency and speed. Determine how this Doppler shift will affect the performance of the system.

Raleigh (5.6.1) Ricean (5.6.2)

2. Explain small scale fading and its significance to the system.

3. What are the Raleigh and Ricean models predicting? What are PDF and CDF functions and how do they apply to the data of interest? What significant differences are there between the Raleigh and Ricean data?

4. When should you apply the Raleigh and Ricean models? How can you apply them to a real system link budget?

AM Modulation (Rappaport 6.2, 6.2.3)

FM Modulation (Rappaport 6.3, 6.3.2, 6.3.3)

• For a given message m(t) and carrier frequency, sketch the transmitted signal.
• Sketch the block diagram of the TX and RX. Explain what each block does and what the signal looks like (in time and/or frequency domains) at each location in the block diagram.
• Compare and contrast Am/FM

Digital Modulation (Handout and Rappaport 6.4, 6.4.1, 6.5, 6.6, 6.7)

• For a given digital data stream d(t), sketch the transmitted signal for BPSK, QPSK, DPSK, FSK.
• Sketch the block diagram of the TX and RX. Explain what each block does and what the signal looks like (in time and/or frequency domains) at each location in the block diagram.
• Explain what pulse shaping is and why it is used. Roughly sketch pulse trains for signals with RC, sinc,Gaussian, and rectangular pulses.
• Explain and sketch the eye diagrams. How do they change when you add noise, have drifts (change) in the carrier frequency, have synchronization (phase delay) problems, etc.?
• Compare and contrast BPSK, QPSK, DPSK, FSK.
• Compare and contrast analog and digital modulation.

Spread Spectrum (CDMA) (DSSS)

• Explain what a PN code is and how it is used to spread the spectrum. Why use spread spectrum?
• Sketch the block diagram of the TX and RX. Explain what each block does and what the signal looks like (in time and/or frequency domains) at each location in the block diagram.