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<html><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><!--Converted with jLaTeX2HTML 2002 (1.62) JA patch-1.4patched version by: Kenshi Muto, Debian Project.LaTeX2HTML 2002 (1.62),original version by: Nikos Drakos, CBLU, University of Leeds* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan* with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --><HTML><HEAD><TITLE>18.3.2 Using shadowing model</TITLE><META NAME="description" CONTENT="18.3.2 Using shadowing model"><META NAME="keywords" CONTENT="everything"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"><META NAME="Generator" CONTENT="jLaTeX2HTML v2002 JA patch-1.4"><META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"><LINK REL="STYLESHEET" HREF="everything.css" tppabs="http://www.isi.edu/nsnam/ns/doc/everything.css"><LINK REL="previous" HREF="node219.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node219.html"><LINK REL="up" HREF="node218.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node218.html"><LINK REL="next" HREF="node221.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node221.html"></HEAD><BODY ><!--Navigation Panel--><A NAME="tex2html4646" HREF="node221.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node221.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html4640" HREF="node218.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node218.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html4636" HREF="node219.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node219.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html4642" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html4644" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html4647" HREF="node221.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node221.html">18.4 Communication range</A><B> Up:</B> <A NAME="tex2html4641" HREF="node218.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node218.html">18.3 Shadowing model</A><B> Previous:</B> <A NAME="tex2html4637" HREF="node219.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node219.html">18.3.1 Backgroud</A>   <B> <A NAME="tex2html4643" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html4645" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <BR><BR><!--End of Navigation Panel--><H2><A NAME="SECTION031532000000000000000">18.3.2 Using shadowing model</A></H2><P>Before using the model, the user should select the values of the pathloss exponent and the shadowing deviation according to the simulated environment.<P>The OTcl interface is still the <TT>node-config</TT> command. One way touse it is as follows, and the values for these parameters are just examples.<P><PRE># first set values of shadowing modelPropagation/Shadowing set pathlossExp_ 2.0 ;# path loss exponentPropagation/Shadowing set std_db_ 4.0 ;# shadowing deviation (dB)Propagation/Shadowing set dist0_ 1.0 ;# reference distance (m)Propagation/Shadowing set seed_ 0 ;# seed for RNG$ns_ node-config -propType Propagation/Shadowing</PRE><P>The shadowing model creates a random number generator (RNG) object. The RNG hasthree types of seeds: raw seed, pre-defined seed (a set of known good seeds)and the huristic seed (details in Section <A HREF="node248.html#sec:random" tppabs="http://www.isi.edu/nsnam/ns/doc/node248.html#sec:random">22.1</A>). Theabove API only uses the pre-defined seed. If a user want different seedingmethod, the following API can be used.<P><PRE>set prop [new Propagation/Shadowing]$prop set pathlossExp_ 2.0$prop set std_db_ 4.0$prop set dist0_ 1.0$prop seed \<seed-type\> 0 ;# user can specify seeding method$ns_ node-config -propInstance $prop</PRE><P>The <TT>seed-type</TT> above can be <TT>raw</TT>, <TT>predef</TT> or <TT>heuristic</TT>.<P><BR><HR><ADDRESS>2003-09-23</ADDRESS></BODY></HTML>⌨️ 快捷键说明
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