1. Wireless Communications Principles and Practice 2nd Edition T. S
Wireless Communications Principles and Practice 2nd Edition T.S. Rappaport
Chapter 5: Mobile Radio Propagation: Small-Scale Fading and Multipath as it applies to Modulation Techniques

2. Doppler Shift Geomerty

3. Channel issues
Fig. 3.2

4. Example 5.1
Consider a transmitter which radiates a sinusoidal carrier frequency of 1850 MHz. For a vehicle moving 60 mph, compute the received carrier frequency if the mobile is moving
directly towards the transmitter
directly away from the transmitter
in a direction which is perpendicular to the direction of arrival of the transmitted signal.

5. Solution 5.1

6. Solution 5.1

7. Complex Baseband model for RF systems

8. Time-varying impulse response
Fig. 2.3

9. Measured impulse responses

10. Channel Sounder: Pulse type

11. Channel Sounder: PN Type
Fig. 2.4

12. Channel Sounder: Swept Freq. type
Fig. 2.5

13. Measured power delay profiles
Fig. 2.6

14. Indoor Power Delay Profile
Fig. 2.7

15. Typical RMS delay spreads
Fig. 2.16

16. Time Dispersion Parameters

17. Time Dispersion Parameters
The mean excess delay is the first moment of the power delay profile and is defined to be (5.35) The rms delay spread is the square root of the second central moment of the power delay profile and is defined to be (5.36) (5.37)

18. Time Dispersion Parameters

19. Example 5.2
Assume a discrete channel impulse response is used to model urban radio channels with excess delays as large as 100 s and microcellular channels with excess delays no larger than 4 s. If the number of multipath bins is fixed at 64, find a) , and b) the maximum bandwidth which the two models can accurately represent. Repeat the exercise for an indoor channel model with excess delays as large as 500 ns. As described in section 4.7.6, SIRCIM and SMRCIM are statistical channel models based on equation (5.12) that use parameters in this example.

20. Solution 5.2

21. Example 5.3

22. Solution 5.3

23. Solution 5.3

24. Solution 5.3

25. Solution 5.3

26. Example 5.4
Calculate the mean excess delay, rms delay spread, and the maximum excess delay (10 dB) for the multipath profile given in the figure below.
Estimate the 50% coherence bandwidth of the channel.
Would this channel be suitable for AMPS or GSM service without the use of an equalizer?

27. Solution 5.4
The rms delay spread for the given multipath profile can be obtained using equations (5.35)-(5.37).
The delays of each profile are measured relative to the first detectable signal.
The mean excess delay for the given profile
The second moment for the given power delay profile can be calculated as

28. Solution 5.4

29. Example 5.5

30. Solution 5.5

31. Solution 5.5

32. Solution 5.5

33. Solution 5.5

34. Solution 5.5

35. Solution 5.5

36. Two independent fading issues
Fig. 2.8

37. Flat-fading (non-freq. Selective)
Fig. 2.9

38. Frequency selective fading
Fig. 2.10

39. Two independent fading issues
Fig. 2.11

40. Rayleigh fading
Fig. 2.12

41. Small-scale envelope distributions
Fig. 2.13

42. Ricean and Rayleigh fading distributions
Fig. 2.14

43. Small-scale fading mechanism
Fig. 2.15

44. Doppler Effect and Frequency Variations Doppler spectrum
Fig. 2.16

45. Spectrum of Envelope of doppler faded signal
Fig. 2.16

46. Simulating Doppler/Small-scale fading
Fig. 2.16

47. Simulating Doppler fading
Fig. 2.16

48. Simulating Doppler fading
Fig. 2.16

49. Simulating multipath with Doppler-induced Rayleigh fading
Fig. 2.16

50. Simulating 2-ray multipath
Fig. 2.16

51. SIRCIM Simulation of all indoor propagation Characteristics
Fig. 2.16

52. SMRCIM Simulation of all outdoor propagation Characteristics
Fig. 2.16

53. SIRCIM and SMRCIM Available from Wireless Valley Communications, Inc.
Source code in C is available
www. Wirelessvalley.com

54. Angular Spread model
Fig. 2.16

55. Spatial distribution of Multipath
Fig. 2.16

56. Angular Spread key to fading
Fig. 2.16

57. Spatial orientation of multipath impacts the depths of fading
Fig. 2.16

58. Angular Distribution of power
Fig. 2.16

59. Angular Spread predicts correlation distances
Fig. 2.16

60. Angular Spread predicts correlation distances
Fig. 2.16

61. Example 5.6

62. Solution 5.6