Ali Al-Saihati ID#

OUTLINE AWGN Channel. Rayleigh Fading Channel. Programs.

AWGN Channel Received signal: Noise power spectral density:

Rayleigh Fading Channel. The transmitted signal from a base station radiates in all directions. Some of the transmitted waves are reflected, diffracted or scattered. Reflection occurs when a wave impinges upon a smooth surface of large size relative to λ (wavelength). Diffraction occurs when the path is blocked by an object with large dimensions relative to λ and sharp irregularities (edges). Scattering occurs when a wave impinges upon an object with dimensions on the order of λ or less. The phase of the received signals varies. Depending on the value of the phase, they might add constructively or destructively.

If N is large: r(t) can be expressed in terms of amplitude and phase Where R(t) and Ѳ(t) are:

Doppler Shift Any motion in the plane in which the electromagnetic wave is traveling towards or away from the receiver results in a shift in the carrier frequency. If the transmitter and receiver are approaching, the frequency is higher while if they are moving apart, the frequency is lower. The Doppler shift is given by: f d = v cos Ѳ /λ

Programs 1) mvalue: Calculates the mean of a given data. 2) disper: Calculates the variance and standard deviation of a given data. 3) main: Calculates mean, variance and standard deviation for a given data. 4) comb: Generates additive white Gaussian noise. 5) fade: Generate Rayleigh fading. 6) sefade: Generates frequency selecting fading. 7) delay: Gives delay to input signal. 8) bpskev: Evaluation program of fading counter based BPSK transmission scheme

Evaluation program of fading counter The fading counter is updated after each simulation loop. The simulation time could be reduced by adjusting the update time. When the update time is equal to the observation time, the transmission performance could be evaluated under continuous changed signal level. It takes a long time to stabilize the simulated performance. When the update time is larger than the observation time, the transmission performance could be evaluated under Rayleigh fading with a small number of simulation loops. The simulation result may not be precise.

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