Construct bell-shaped Doppler spectrum object
doppler.bell creates a bell Doppler spectrum object. You can use this object with the DopplerSpectrum property of any channel object created with either the rayleighchan function, the ricianchan function, or comm.MIMOChannel System object™.
dop = doppler.bell creates a bell Doppler spectrum object with default coefficient.
dop = doppler.bell(coeffbell) creates a bell Doppler spectrum object with coefficient given by coeffbell, where coeffbell is a positive, finite, real scalar.
The bell Doppler spectrum object has the following properties.
|SpectrumType||Fixed value, 'Bell'|
|CoeffBell||Bell spectrum coefficient, positive real finite scalar.|
A bell spectrum was proposed in  for the Doppler spectrum of indoor MIMO channels, for 802.11n channel modeling.
The normalized bell Doppler spectrum is given analytically by:
fd represents the maximum Doppler shift specified for the channel object, and A represents a positive real finite scalar (CoeffBell). The indoor MIMO channel model of IEEE 802.11n  uses the following parameter: A = 9. Since the channel is modeled as Rician fading with a fixed line-of-sight (LOS) component, a Dirac delta is also present in the Doppler spectrum at f = 0.
Construct a bell Doppler spectrum object with a coefficient of 8.5. Assign it to a Rayleigh channel object with one path.
dop = doppler.bell(8.5); chan = rayleighchan(1e-5, 10); chan.DopplerSpectrum = dop;