Chapter 5 Mobile Radio Propagation SmallScale Fading and
Chapter 5: Mobile Radio Propagation: Small-Scale Fading and Multipath as it applies to Modulation Techniques © 2002 Pearson Education, Inc. Commercial use, distribution, or Principles and Practice 2 nd Edition T. S. Rappaport sale prohibited. Wireless Communications
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Doppler Shift Geomerty
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Channel issues
© 2002 Pearson Education, Inc. Commercial use, distribution, or 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 a) directly towards the transmitter b) directly away from the transmitter c) in a direction which is perpendicular to the direction of arrival of the transmitted signal. sale prohibited. Example 5. 1
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 1
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 1
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Complex Baseband model for RF systems
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Channel Sounder: Pulse type
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Channel Sounder: PN Type
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Channel Sounder: Swept Freq. type
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Measured power delay profiles
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Time Dispersion Parameters •
Time Dispersion Parameters The mean excess delay is the first moment of the power delay profile and is defined to be (5. 37) © 2002 Pearson Education, Inc. Commercial use, distribution, or 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) sale prohibited. (5. 35)
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Time Dispersion Parameters •
Example 5. 2 a) , and © 2002 Pearson Education, Inc. Commercial use, distribution, or If the number of multipath bins is fixed at 64, find sale prohibited. 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. 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.
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 3
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 3
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 3
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 3
Estimate the 50% coherence bandwidth of the channel. Would this channel be suitable for AMPS or GSM service without the use of an equalizer? © 2002 Pearson Education, Inc. Commercial use, distribution, or Calculate the mean excess delay, rms delay spread, and the maximum excess delay (10 d. B) for the multipath profile given in the figure below. sale prohibited. Example 5. 4
Solution 5. 4 The rms delay spread for the given multipath profile can be obtained using equations (5. 35)-(5. 37). The second moment for the given power delay profile can be calculated as © 2002 Pearson Education, Inc. Commercial use, distribution, or The mean excess delay for the given profile sale prohibited. The delays of each profile are measured relative to the first detectable signal.
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 4 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Example 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 5 •
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Two independent fading issues
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Frequency selective fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Two independent fading issues
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Rayleigh fading
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Doppler Effect and Frequency Variations Doppler spectrum
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© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Simulating Doppler/Small-scale fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Simulating Doppler fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Simulating Doppler fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Simulating multipath with Doppler-induced Rayleigh fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Simulating 2 -ray multipath
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. SIRCIM Simulation of all indoor propagation Characteristics
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. SMRCIM Simulation of all outdoor propagation Characteristics
© 2002 Pearson Education, Inc. Commercial use, distribution, or • Available from Wireless Valley Communications, Inc. • Source code in C is available • www. Wirelessvalley. com sale prohibited. SIRCIM and SMRCIM
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Angular Spread model
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Spatial distribution of Multipath
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Angular Spread key to fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Spatial orientation of multipath impacts the depths of fading
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Angular Distribution of power
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Angular Spread predicts correlation distances
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Angular Spread predicts correlation distances
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Example 5. 6
© 2002 Pearson Education, Inc. Commercial use, distribution, or sale prohibited. Solution 5. 6
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