Communications Blockset

Rician Fading Channel

Simulate a Rician fading propagation channel

Library

Channels

Description

The Rician Fading Channel block implements a baseband simulation of a Rician fading propagation channel. This block is useful for modeling mobile wireless communication systems when the transmitted signal can travel to the receiver along a dominant line-of-sight or direct path. If the signal can travel along a line-of-sight path and also along other fading paths, then you can use this block in parallel with the Multipath Rayleigh Fading Channel block. For details about fading channels, see the works listed in References.

The input can be either a scalar or a frame-based column vector. The input is a complex signal.

Fading causes the signal to spread and become diffuse. The K-factor parameter, which is part of the statistical description of the Rician distribution, represents the ratio between direct-path (unspread) power and diffuse power. The ratio is expressed linearly, not in decibels. While the Gain parameter controls the overall gain through the channel, the K-factor parameter controls the gain's partition into direct and diffuse components.

Relative motion between the transmitter and receiver causes Doppler shifts in the signal frequency. The Doppler frequency parameter is the maximum Doppler shift that the signal undergoes. The Jakes PSD (power spectral density) determines the spectrum of the Rician process.

The Sample time parameter is the time between successive elements of the input signal. Note that if the input is a frame-based column vector of length n, then the frame period (as Simulink's Probe block reports, for example) is n*Sample time.

The Delay parameter specifies a time delay in seconds and the Gain parameter specifies a gain that applies to the input signal. Both parameters are scalars.

The scalar Initial seed parameter seeds the random number generator that the block uses to generate its Rician-distributed complex random process.

Dialog Box

K-factor

The ratio of power in the direct path to diffuse power. The ratio is expressed linearly, not in decibels.

Doppler frequency (Hz)

A positive scalar that indicates the maximum Doppler shift.

Sample time

The period of each element of the input signal.

Delay (s)

A scalar that specifies the propagation delay.

Gain (dB)

A scalar that specifies the gain.

Initial seed

The scalar seed for the Gaussian noise generator.

See Also

Rician Noise Generator, Multipath Rayleigh Fading Channel

References

Fechtel, Stefan A. "A Novel Approach to Modeling and Efficient Simulation of Frequency-Selective Fading Radio Channels." IEEE Journal on Selected Areas in Communications, vol. 11, April 1993. 422-431.

Jakes, William C., ed. Microwave Mobile Communications. New York: IEEE Press, 1974.

Lee, William C. Y. Mobile Communications Design Fundamentals, 2nd ed. New York: Wiley, 1993.

Rectangular QAM Modulator Passband

Rician Noise Generator