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<?xml version="1.0"?>
<!--
###################################################
##Frequency Selective Fading Model
###################################################
-->
<block>
<name>Frequency Selective Fading Model2</name>
<key>channels_selective_fading_model2</key>
<import>from gnuradio import channels</import>
<make>channels.selective_fading_model2( $N, $fDTs, $LOS, $K, $seed, $delays, $delay_std, $delay_maxdev, $mags, $ntaps )</make>
<callback>set_fDTs($fDTs)</callback>
<callback>set_K($K)</callback>
<param>
<name>Num Sinusoids (Stochastic SoS model + delay drift)</name>
<key>N</key>
<value>8</value>
<type>int</type>
</param>
<param>
<name>Normalized Max Doppler (fD*Ts)</name>
<key>fDTs</key>
<value>0.2/samp_rate</value>
<type>real</type>
</param>
<param>
<name>LOS Model</name>
<key>LOS</key>
<type>enum</type>
<option>
<name>Rayleigh/NLOS</name>
<key>False</key>
<opt>hide_K:all</opt>
</option>
<option>
<name>Rician/LOS</name>
<key>True</key>
<opt>hide_K:</opt>
</option>
</param>
<param>
<name>Rician factor (K)</name>
<key>K</key>
<value>4.0</value>
<type>real</type>
<hide>$LOS.hide_K</hide>
</param>
<param>
<name>Seed</name>
<key>seed</key>
<value>0</value>
<type>int</type>
</param>
<param>
<name>PDP Delays (in samps)</name>
<key>delays</key>
<value>1.0,1.9,2.7</value>
<type>real_vector</type>
</param>
<param>
<name>PDP Delay StdDev (per samp)</name>
<key>delay_std</key>
<value>1e-4,1e-4,1e-4</value>
<type>real_vector</type>
</param>
<param>
<name>PDP Delay Max-Dev (per samp)</name>
<key>delay_maxdev</key>
<value>0.5,0.7,0.9</value>
<type>real_vector</type>
</param>
<param>
<name>PDP Magnitudes</name>
<key>mags</key>
<value>1,0.95,0.8</value>
<type>real_vector</type>
</param>
<param>
<name>Num Taps</name>
<key>ntaps</key>
<value>8</value>
<type>int</type>
</param>
<sink>
<name>in</name>
<type>complex</type>
</sink>
<source>
<name>out</name>
<type>complex</type>
</source>
<source>
<name>taps</name>
<type>message</type>
<optional>1</optional>
</source>
<doc>
int d_N=8; // number of sinusoids used to simulate gain on each ray
float d_fDTs=0.01 // normalized maximum doppler frequency (f_doppler / f_samprate)
float d_K=4; // Rician factor (ratio of the specular power to the scattered power)
bool d_LOS=true; // LOS path exists? chooses Rician (LOS) vs Rayleigh (NLOS) model.
int seed=0; // noise seed
int ntaps; // Number of FIR taps to use in selective fading model
These two vectors comprise the Power Delay Profile of the signal
float_vector delays // Time delay in the fir filter (in samples) for each arriving WSSUS Ray
float_vector mags // Magnitude corresponding to each WSSUS Ray
If using a LOS model, the first delay and mag should correspond with the LOS component
References:
The flat-fading portion of the algorithm implements the following
Compact Rayleigh and Rician fading simulator based on random walk processes
A. Alimohammad S.F. Fard B.F. Cockburn C. Schlegel
26th November 2008
(Alogrithm III)
( with a novel addition of time delay tap random walk )
The frequency selective extension of the block roughly implements
A Low-Complexity Hardware Implementation of Discrete-Time
Frequency-Selective Rayleigh Fading Channels
F. Ren and Y. Zheng
24-27 May 2009
Implementation by Tim O'Shea
</doc>
</block>
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