BPSK singlepath Rayleigh channel

In summary, the conversation discusses the aim of deriving and simulating the error rate performance of binary PSK when transmitted over a single-path slowly fading channel. The frequency-nonselective channel results in multiplicative distortion and the received signal can be processed using a matched filter for ideal coherent detection. The error rate of binary PSK can be expressed as a function of the received SNR, and the steps to compute it are suggested, including taking the convolution of the received signal with a matched filter and considering the possible output signal values. The pdf of the output noise must also be obtained before computing the error probability.
  • #1
yongs90
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Homework Statement


The aim of this exercise is to derive and simulate the error rate performance
of binary PSK when the signal is transmitted over a single-path (or frequency
non-selective) slowly fading channel. The frequency-nonselective channel results
in multiplicative distortion of the transmitted signal s(t). In addition, the con-
dition that the channel fades slowly implies that the multiplicative process may
be regarded as a constant during at least one signaling interval. Therefore, the
received equivalent lowpass signal in one signaling interval is

r(t) = [itex]\alpha[/itex] * exp(j * [itex]\phi[/itex]) * s(t) + z(t) 0 [itex]\leq[/itex] t [itex]\leq[/itex] ts

where z(t) represents the complex-valued white Gaussian noise process with
power spectral density [itex]N_0[/itex]/2

Assume that the channel fading is sufficiently slow that the phase shift, [itex]\phi[/itex] can
be estimated from the received signal without error. Then, we can achieve ideal
coherent detection of the received signal. The received signal can be processed
by passing it through a matched filter. Show that for a fixed (time-invariant)
channel, i.e., for a fixed attenuation [itex]\alpha[/itex], the error rate of binary PSK as a function
of the received SNR, [itex]\gamma[/itex] is
[itex]P_b[/itex]([itex]\gamma[/itex]) = Q([itex]\sqrt{}2\gamma[/itex])
where [itex]\gamma[/itex] = [itex]\alpha^2 E_b / N_0[/itex] and [itex]E_b[/itex] is the energy of the transmitted signal per bit.

Homework Equations


The Attempt at a Solution


Can someone give me an idea on how to start..
 
Last edited:
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  • #2
How do I go about it
i) Take the convolution of r(t) with the impulse response of a filter matched to s(t). Consider output signal and output noise separately.
ii) Remember that the modulation method is binary PSK, which means the phase shift is either 0 or pi. What is the possible output signal values?
iii) Before you compute error probability, you must obtain the pdf of the output noise.
 
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