Rabin Bhusal (20117737)– Assignment 2
Mobile Radio Engineering(14151)
# Compare the performance in terms of Bit Error rate (BER) vs. Signal to Noise Ratio (Eb/no)
plot for the Radio propagation over,
1. Rayleigh Faded Channel
2. Rician Faded Channel
Rayleigh Faded Channel
Rayleigh fading is a statistical model for the effect of a propagation environment on a radio
channel that occurs when there are multiple indirect paths between transmitters and receiver
and no distinct dominant path, such as an LOS path. This represents a worst case scenario.
Fortunately, Rayleigh fading can be dealt with analytically, providing insights into
performance characteristics that can be used in difficult environments, such as for
tropospheric and ionospheric signal propagation as well as heavy urban environments.
Rician Faded Channel
Rician fading best characterizes a situation where there is a direct LOS path in addition to
a number of indirect multipath signals. The Rician model is often applicable in an indoor
environment whereas the Rayleigh model characterizes outdoor settings. The Rician model
also becomes more applicable in smaller cells or in more open outdoor environments. The
channels can be characterized by a parameter K, defined as follows:
Power in the dominant path
K= ----------------------------------------
Power in the scattered paths
When K = 0 the channel is Rayleigh (i.e., numerator is zero) and when K =∞, the channel is
AWGN (i.e., denominator is zero).
Simulation Procedure
Using MATLAB generation of graph for BER vs. SNR for DPSK modulation scheme has
been done. Firstly a channel is described where Rayleigh fading is implemented by the code,
chan = rayleighchan(ts,fd)
Where, ts = Sampling Time in seconds & fd = Doppler Frequency shift in Hz.
Then another channel is described where Rician fading is implemented by the code,
chan1 = ricianchan(ts,fd,k)
Where, ts = Sampling Time in seconds & fd = Doppler Frequency shift in Hz & k = Rician K Factor.
Then a modulator and demodulator are described. Differential phase shift keying modulator
and demodulator with modulation order of 2 have been used in this case for illustration
purpose only.
