ELEC 456 - Mobile Communications
Assignment #1 - Due Feb. 12, 1999

*** Since this is a long assignment, it may have more value than other assignments ***

  1. Is cellular radio system capacity limited by noise or by interference?
    Explain why this is the case.
  2. Which of TDMA, CDMA, and GSM cellular systems is inherently suited to data services? Why?
  3. Briefly describe the major sources of CCI and ACI.
  4. What is frequency re-use and what factors limit re-use in a practical cellular system?
  5. Assuming a regular hexagonal tessellation, what are the first five cluster sizes and the corresponding distances between cocells?
  6. Find the re-use distance D/R if the required CCI is 18 dB with a = 3.5. What is the corresponding minimum cluster size?
  7. Consider an AMPS-like system using a multiple-channel bandwidth scheme to increase capacity. If we have a total bandwidth of 12 MHz and we split this bandwidth equally between 20 kHz and 30 kHz channels, what is the total number of channels? For a seven-cell cluster, what is the radius of the inner cell (as a fraction of the radius of the outer cell)? The minimum C/Ic for the 20 and 30 kHz bands is 22 dB and 18 dB, respectively. Use a = 4.
  8. Use Okumura’s model to find the propagation loss in dB for an open area with:
    f = 1 GHz, ht = 20 m, Pt = 5W, Gt = 4, Gr = 2, hr = 2 m, d = 10 km.
    Check the result using Hata’s formula.
  9. Using sx2 = 1, plot the Rican PDF p(r) for a = 0, a = 1 and for a = 2. As shown in figure on page 72 of the course notes, be sure to normalize a for the computation and normalize r for the plot axis.
  10. Find the shadow loss when the wavelength is l = 25 cm, the distance from the obstruction to the mobile is d1 = 1 km, the distance from the base to the obstruction is d2 = 6 km, and the height of the obstruction is h = 10 m. Repeat with d1 = 2 km and d2 = 5 km. Explain the difference between the answers in view of the fact that in both cases the total distance is 7 km.