%?Determine?sample?（1）?echo?delay?times?（2）?norm.?Doppler?frequencies
%?and?（3）?initial?phases?of?the?Rayleigh?portions?of?a?（time-variant）
%?physical?transmission?channel?according?to?the?European?standard?COST-
%?207?（COoperation?in?the?field?of?Science?&?Technology?Project?#207）.
%
%?function?[tau_MHz?fD_norm?psi?tau_pdf]?=?...
%??????????????????????????????????COST207?（mPDS[?N_echo[?rseed]]]）
%?----------------------------------------------------------------------
%?INPUT:
%?----------------------------------------------------------------------
%?mPDS????:??String?designating?the?desired?propagation?environment
%????????????i.e.?the?physical?channel?according?to?COST-207:
%????????????-?‘TU‘:??“Typical?Urban“??（non-hilly?urban?environment）
%????????????-?‘RA‘:??“Rural?Area“?????（non-hilly?rural?environment）
%????????????-?‘BU‘:??“Bad?Urban“??????（hilly?urban?environment）
%????????????-?‘HT‘:??“Hilly?Terrain“??（hilly?rural?environment）.
%?????Note:??These?environments?correspond?to?different?mean?power?
%????????????delay?spectra?（PDS?“Verzoegerungsleistungsspektren“）.
%?????N.B.:??To?obtain?environments?NOT?standardized?by?COST-207?mPDS
%????????????can?also?be?a?matrix?with?entries?as?in?tau_pdf?（see?o/p）.
%?[N_echo]:??Desired?number?of?echo?paths?（Default:?100）.
%?[rseed]?:??If?this?parameter?is?given?rseed?is?used?to?set?the?
%????????????seeds?for?the?random?numbers?generator.?In?this?way
%????????????the?function?outputs?can?be?reproduced.
%?----------------------------------------------------------------------
%?OUTPUT:
%?----------------------------------------------------------------------
%?tau_MHz:??（Length?N_out）?col.?vector?of?delay?times?of?the?echo?paths.
%???????????The?values?of?tau_MHz?:=?tau*1MHz?=?tau/1us?are?in?the?range?
%???????????0..7?（TU）?0..0.7?（RA）?0..10?（BU）?0..2?and?15..20?（HT）.
%???????????The?histogramm?of?tau_MHz?approaches?the?pdf?of?tau?which
%???????????is?prop.?to?the?mean?power?delay?spectrum?indicated?by?mPDS.
%????N.B.:??N_out?may?slightly?differ?from?N_echo?to?satisfy?the?relative
%???????????power?ratio?between?echo?clusters?（for?‘BU‘?and?‘HT‘?only）.
%?fD_norm:??（Length?N_out）?column?vector?with?norm.?Doppler?frequencies?
%???????????fD/max{fD}?resulting?from?echos?impinging?isotropically?on
%???????????the?mobile?unit.?The?values?are?in?the?range?-1.0...1.0?and
%???????????approximate?the?Jakes?pdf.?To?unnormalize?multiply?by?the?
%???????????maximum?Doppler?frequency?max{fD}:=?v*f0/c0?where
%??????????????-?v???????is?the?speed?of?the?mobile?unit?[m/s]
%??????????????-?f0??????is?the?carrier?frequency?[Hertz]
%??????????????-?c0=3e8??is?the?speed?of?light?in?empty?space?[m/s].
%?psi????:??（Length?N_out）?column?vector?containing?the?initial?phases.
%???????????The?values?are?uniformly?distributed?in?the?range?0..2pi.
%?tau_pdf:??Complete?set?of?parameters?describing?the?pdf?of?echo?delay
%???????????times?where?row?n?refers?to?the?n