A channel model is an essential piece of a physical layer communication simulation. It is a mathematical representation of the effects of a communication channel through which wireless signals are propagated. The channel model is the impulse response of the channel medium in the time domain or its Fourier transform in the frequency domain. In general, the channel impulse response of a wireless communication system varies randomly over time.
By using the right channel model in your design, you can optimize link performance, perform system architecture tradeoffs, and provide a realistic assessment of the overall system performance.
Many factors are considered in building a channel model, such as carrier frequency, bandwidth, the locations of transmitter and receiver, Doppler frequency, medium type, RF polarization, weather conditions, and noise types. Selecting a channel model is a tradeoff between computational efficiency and model fidelity.
The models can be parameterized by channel bandwidth, carrier frequency, Doppler frequency, fading channel profile, etc. The models are available as functions and System objects™ in MATLAB® and as blocks in Simulink®. These models can be used as a part of the design and simulation of your wireless communication systems.