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67  <div class="navpath"><b>itpp</b>::<a class="el" href="classitpp_1_1QAM.html">QAM</a>
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70<div class="contents">
71<h1>itpp::QAM Class Reference<br>
72<small>
73[<a class="el" href="group__modulators.html">Digital Modulation</a>]</small>
74</h1><!-- doxytag: class="itpp::QAM" --><!-- doxytag: inherits="Modulator&lt; std::complex&lt; double &gt; &gt;" -->M-ary <a class="el" href="classitpp_1_1QAM.html" title="M-ary QAM modulator with square lattice.">QAM</a> modulator with square lattice. 
75<a href="#_details">More...</a>
76<p>
77<code>#include &lt;<a class="el" href="modulator_8h-source.html">modulator.h</a>&gt;</code>
78<p>
79
80<p>
81<a href="classitpp_1_1QAM-members.html">List of all members.</a><table border="0" cellpadding="0" cellspacing="0">
82<tr><td></td></tr>
83<tr><td colspan="2"><br><h2>Public Member Functions</h2></td></tr>
84<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="a5b1798b2370c0648a61e102a0e852f3"></a><!-- doxytag: member="itpp::QAM::QAM" ref="a5b1798b2370c0648a61e102a0e852f3" args="()" -->
85&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#a5b1798b2370c0648a61e102a0e852f3">QAM</a> ()</td></tr>
86
87<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Default Constructor. <br></td></tr>
88<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="bcab714c15a168763b39940be2ffb636"></a><!-- doxytag: member="itpp::QAM::QAM" ref="bcab714c15a168763b39940be2ffb636" args="(int M)" -->
89&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#bcab714c15a168763b39940be2ffb636">QAM</a> (int <a class="el" href="classitpp_1_1Modulator.html#a434960c7ff9e5356d832aa53b46930b">M</a>)</td></tr>
90
91<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Class Constructor. <br></td></tr>
92<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3c1e5de708ba4c2c007c5613e7f2d50e"></a><!-- doxytag: member="itpp::QAM::~QAM" ref="3c1e5de708ba4c2c007c5613e7f2d50e" args="()" -->
93virtual&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#3c1e5de708ba4c2c007c5613e7f2d50e">~QAM</a> ()</td></tr>
94
95<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Destructor. <br></td></tr>
96<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="ec5d9e5188bc1ceca2a575f37f806a07"></a><!-- doxytag: member="itpp::QAM::set_M" ref="ec5d9e5188bc1ceca2a575f37f806a07" args="(int M)" -->
97void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#ec5d9e5188bc1ceca2a575f37f806a07">set_M</a> (int <a class="el" href="classitpp_1_1Modulator.html#a434960c7ff9e5356d832aa53b46930b">M</a>)</td></tr>
98
99<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Change the size of the signal constellation. <br></td></tr>
100<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="fa8c6d12e65e8a145faabd11d0d6be92"></a><!-- doxytag: member="itpp::QAM::demodulate_bits" ref="fa8c6d12e65e8a145faabd11d0d6be92" args="(const cvec &amp;signal, bvec &amp;bits) const " -->
101void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#fa8c6d12e65e8a145faabd11d0d6be92">demodulate_bits</a> (const cvec &amp;signal, bvec &amp;bits) const </td></tr>
102
103<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of bits. <br></td></tr>
104<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="bae9938fa352e6e79c7b61e5f2743748"></a><!-- doxytag: member="itpp::QAM::demodulate_bits" ref="bae9938fa352e6e79c7b61e5f2743748" args="(const cvec &amp;signal) const " -->
105bvec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#bae9938fa352e6e79c7b61e5f2743748">demodulate_bits</a> (const cvec &amp;signal) const </td></tr>
106
107<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of bits. <br></td></tr>
108<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="b9722a6826869c6d6e15a9835d76239b"></a><!-- doxytag: member="itpp::QAM::set" ref="b9722a6826869c6d6e15a9835d76239b" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;symbols, const ivec &amp;bits2symbols)" -->
109virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#b9722a6826869c6d6e15a9835d76239b">set</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;<a class="el" href="classitpp_1_1Modulator.html#3069840e9e7a44180615fb772cf9ae42">symbols</a>, const ivec &amp;<a class="el" href="classitpp_1_1Modulator.html#3ca26614189cb7a66da369bf0c4b9070">bits2symbols</a>)</td></tr>
110
111<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Set the constellation to use in the modulator. <br></td></tr>
112<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="6e7cfa06570e2a1de515be5222a53a83"></a><!-- doxytag: member="itpp::QAM::bits_per_symbol" ref="6e7cfa06570e2a1de515be5222a53a83" args="() const" -->
113virtual int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#6e7cfa06570e2a1de515be5222a53a83">bits_per_symbol</a> () const</td></tr>
114
115<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Returns number of bits per symbol. <br></td></tr>
116<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="28b1c28bf8f4596e4d5149f1f3c8cd76"></a><!-- doxytag: member="itpp::QAM::get_symbols" ref="28b1c28bf8f4596e4d5149f1f3c8cd76" args="() const" -->
117virtual <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex<br class="typebreak">
118&lt; double &gt; &gt;&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#28b1c28bf8f4596e4d5149f1f3c8cd76">get_symbols</a> () const</td></tr>
119
120<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Get the symbol values used in the modulator. <br></td></tr>
121<tr><td class="memItemLeft" nowrap align="right" valign="top">virtual ivec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#a8186f0e837fd3d440a6acb7a0225d35">get_bits2symbols</a> () const</td></tr>
122
123<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Get the bitmap, which maps input bits into symbols.  <a href="#a8186f0e837fd3d440a6acb7a0225d35"></a><br></td></tr>
124<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="4f7bde9d3bfa9e39c06017534e3f6647"></a><!-- doxytag: member="itpp::QAM::modulate" ref="4f7bde9d3bfa9e39c06017534e3f6647" args="(const ivec &amp;symbolnumbers, Vec&lt; std::complex&lt; double &gt; &gt; &amp;output) const" -->
125virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#4f7bde9d3bfa9e39c06017534e3f6647">modulate</a> (const ivec &amp;symbolnumbers, <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;output) const</td></tr>
126
127<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of symbols. <br></td></tr>
128<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="e0cb2673987e110920b519c139cdebe1"></a><!-- doxytag: member="itpp::QAM::modulate" ref="e0cb2673987e110920b519c139cdebe1" args="(const ivec &amp;symbolnumbers) const" -->
129virtual <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex<br class="typebreak">
130&lt; double &gt; &gt;&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#e0cb2673987e110920b519c139cdebe1">modulate</a> (const ivec &amp;symbolnumbers) const</td></tr>
131
132<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of symbols. <br></td></tr>
133<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="845b5fbf4dad59edd3772627250623a1"></a><!-- doxytag: member="itpp::QAM::demodulate" ref="845b5fbf4dad59edd3772627250623a1" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal, ivec &amp;output) const" -->
134virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#845b5fbf4dad59edd3772627250623a1">demodulate</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;signal, ivec &amp;output) const</td></tr>
135
136<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Demodulation of symbols. <br></td></tr>
137<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="7f2c15efa18d1cb46b8c97723c11ec9d"></a><!-- doxytag: member="itpp::QAM::demodulate" ref="7f2c15efa18d1cb46b8c97723c11ec9d" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal) const" -->
138virtual ivec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#7f2c15efa18d1cb46b8c97723c11ec9d">demodulate</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;signal) const</td></tr>
139
140<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Demodulation of symbols. <br></td></tr>
141<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="53826bf7e0ec83b99592235b0c2f6235"></a><!-- doxytag: member="itpp::QAM::modulate_bits" ref="53826bf7e0ec83b99592235b0c2f6235" args="(const bvec &amp;bits, Vec&lt; std::complex&lt; double &gt; &gt; &amp;output) const" -->
142virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#53826bf7e0ec83b99592235b0c2f6235">modulate_bits</a> (const bvec &amp;bits, <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;output) const</td></tr>
143
144<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of bits. <br></td></tr>
145<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="622fa1ce4243330b7efa0605a9492513"></a><!-- doxytag: member="itpp::QAM::modulate_bits" ref="622fa1ce4243330b7efa0605a9492513" args="(const bvec &amp;bits) const" -->
146virtual <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex<br class="typebreak">
147&lt; double &gt; &gt;&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#622fa1ce4243330b7efa0605a9492513">modulate_bits</a> (const bvec &amp;bits) const</td></tr>
148
149<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of bits. <br></td></tr>
150<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="4d03bbe8bd467898f149d5f134f6f120"></a><!-- doxytag: member="itpp::QAM::demodulate_bits" ref="4d03bbe8bd467898f149d5f134f6f120" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal, bvec &amp;bits) const" -->
151virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#4d03bbe8bd467898f149d5f134f6f120">demodulate_bits</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;signal, bvec &amp;bits) const</td></tr>
152
153<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of bits. <br></td></tr>
154<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="9e3432dad687ac0ee102c208e34920f8"></a><!-- doxytag: member="itpp::QAM::demodulate_bits" ref="9e3432dad687ac0ee102c208e34920f8" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal) const" -->
155virtual bvec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#9e3432dad687ac0ee102c208e34920f8">demodulate_bits</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;signal) const</td></tr>
156
157<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of bits. <br></td></tr>
158<tr><td class="memItemLeft" nowrap align="right" valign="top">virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#9beffaf8f69378f9c20a85f3023bd9af">demodulate_soft_bits</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, double N0, vec &amp;soft_bits, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const</td></tr>
159
160<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for AWGN channels.  <a href="#9beffaf8f69378f9c20a85f3023bd9af"></a><br></td></tr>
161<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="a9cba88e460e11775fb72d21b543c375"></a><!-- doxytag: member="itpp::QAM::demodulate_soft_bits" ref="a9cba88e460e11775fb72d21b543c375" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, double N0, Soft_Method method=LOGMAP) const" -->
162virtual vec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#a9cba88e460e11775fb72d21b543c375">demodulate_soft_bits</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, double N0, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const</td></tr>
163
164<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for AWGN channels. <br></td></tr>
165<tr><td class="memItemLeft" nowrap align="right" valign="top">virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#bd014d868b4f883712f92a7130401714">demodulate_soft_bits</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;channel, double N0, vec &amp;soft_bits, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const</td></tr>
166
167<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for fading channels.  <a href="#bd014d868b4f883712f92a7130401714"></a><br></td></tr>
168<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="e40b7afd0d38d2d86b561b9dff6f55fd"></a><!-- doxytag: member="itpp::QAM::demodulate_soft_bits" ref="e40b7afd0d38d2d86b561b9dff6f55fd" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, const Vec&lt; std::complex&lt; double &gt; &gt; &amp;channel, double N0, Soft_Method method=LOGMAP) const" -->
169virtual vec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#e40b7afd0d38d2d86b561b9dff6f55fd">demodulate_soft_bits</a> (const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt; &amp;channel, double N0, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const</td></tr>
170
171<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for fading channels. <br></td></tr>
172<tr><td colspan="2"><br><h2>Protected Member Functions</h2></td></tr>
173<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="bb3e654a3fb6d127ee8d266677689233"></a><!-- doxytag: member="itpp::QAM::calculate_softbit_matrices" ref="bb3e654a3fb6d127ee8d266677689233" args="()" -->
174void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#bb3e654a3fb6d127ee8d266677689233">calculate_softbit_matrices</a> ()</td></tr>
175
176<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">This function calculates the soft bit mapping matrices S0 and S1. <br></td></tr>
177<tr><td colspan="2"><br><h2>Protected Attributes</h2></td></tr>
178<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="d2c1d5047f75d9a43e0a7c165a69d165"></a><!-- doxytag: member="itpp::QAM::L" ref="d2c1d5047f75d9a43e0a7c165a69d165" args="" -->
179int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#d2c1d5047f75d9a43e0a7c165a69d165">L</a></td></tr>
180
181<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">The square-root of M. <br></td></tr>
182<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="234cc9d2e3b6a0eb76af03371e3472a9"></a><!-- doxytag: member="itpp::QAM::scaling_factor" ref="234cc9d2e3b6a0eb76af03371e3472a9" args="" -->
183double&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1QAM.html#234cc9d2e3b6a0eb76af03371e3472a9">scaling_factor</a></td></tr>
184
185<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Scaling factor of square <a class="el" href="classitpp_1_1QAM.html" title="M-ary QAM modulator with square lattice.">QAM</a> constellation (sqrt((M-1)*2/3)). <br></td></tr>
186<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="552cd7add3e998eca485d0ea39808e0d"></a><!-- doxytag: member="itpp::QAM::setup_done" ref="552cd7add3e998eca485d0ea39808e0d" args="" -->
187bool&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#552cd7add3e998eca485d0ea39808e0d">setup_done</a></td></tr>
188
189<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Setup indicator. <br></td></tr>
190<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3656edc52486e0551b734b32ab67d3b6"></a><!-- doxytag: member="itpp::QAM::k" ref="3656edc52486e0551b734b32ab67d3b6" args="" -->
191int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#3656edc52486e0551b734b32ab67d3b6">k</a></td></tr>
192
193<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Number of bits per modulation symbol. <br></td></tr>
194<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="a434960c7ff9e5356d832aa53b46930b"></a><!-- doxytag: member="itpp::QAM::M" ref="a434960c7ff9e5356d832aa53b46930b" args="" -->
195int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#a434960c7ff9e5356d832aa53b46930b">M</a></td></tr>
196
197<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Number of modulation symbols. <br></td></tr>
198<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="1b1a9a706c0736c51966703bea58cf48"></a><!-- doxytag: member="itpp::QAM::bitmap" ref="1b1a9a706c0736c51966703bea58cf48" args="" -->
199<a class="el" href="mat_8h.html#f90acd1af41bf2d1d8a4bb23662fff69">bmat</a>&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#1b1a9a706c0736c51966703bea58cf48">bitmap</a></td></tr>
200
201<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Bit to symbol mapping table (size: M x k). <br></td></tr>
202<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3ca26614189cb7a66da369bf0c4b9070"></a><!-- doxytag: member="itpp::QAM::bits2symbols" ref="3ca26614189cb7a66da369bf0c4b9070" args="" -->
203ivec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#3ca26614189cb7a66da369bf0c4b9070">bits2symbols</a></td></tr>
204
205<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Bit to symbol mapping in decimal form (size: M). <br></td></tr>
206<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3069840e9e7a44180615fb772cf9ae42"></a><!-- doxytag: member="itpp::QAM::symbols" ref="3069840e9e7a44180615fb772cf9ae42" args="" -->
207<a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt; &gt;&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#3069840e9e7a44180615fb772cf9ae42">symbols</a></td></tr>
208
209<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Corresponding modulation symbols (size: M). <br></td></tr>
210<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="c19c8fe07e95e4eb80e832a633b7c422"></a><!-- doxytag: member="itpp::QAM::S0" ref="c19c8fe07e95e4eb80e832a633b7c422" args="" -->
211imat&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#c19c8fe07e95e4eb80e832a633b7c422">S0</a></td></tr>
212
213<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Matrix where row k contains the constellation points with '0' in bit position k. <br></td></tr>
214<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="9d4c223ffd96fdc5b26ba5c44956998b"></a><!-- doxytag: member="itpp::QAM::S1" ref="9d4c223ffd96fdc5b26ba5c44956998b" args="" -->
215imat&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#9d4c223ffd96fdc5b26ba5c44956998b">S1</a></td></tr>
216
217<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Matrix where row k contains the constellation points with '1' in bit position k. <br></td></tr>
218<tr><td colspan="2"><br><h2>Related Functions</h2></td></tr>
219<tr><td colspan="2">(Note that these are not member functions.) <br><br></td></tr>
220<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="d47d1377dffb2aed9f21f8f976e80a0a"></a><!-- doxytag: member="itpp::QAM::Modulator_1D" ref="d47d1377dffb2aed9f21f8f976e80a0a" args="" -->
221typedef <a class="el" href="classitpp_1_1Modulator.html">Modulator</a>&lt; double &gt;&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#d47d1377dffb2aed9f21f8f976e80a0a">Modulator_1D</a></td></tr>
222
223<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Definition of 1D Modulator (with real symbols). <br></td></tr>
224<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="97dc4e87ae4fa63c4e7dbbeac0ab00b0"></a><!-- doxytag: member="itpp::QAM::Modulator_2D" ref="97dc4e87ae4fa63c4e7dbbeac0ab00b0" args="" -->
225typedef <a class="el" href="classitpp_1_1Modulator.html">Modulator</a><br class="typebreak">
226&lt; std::complex&lt; double &gt; &gt;&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#97dc4e87ae4fa63c4e7dbbeac0ab00b0">Modulator_2D</a></td></tr>
227
228<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Definition of 2D Modulator (with complex symbols). <br></td></tr>
229</table>
230<hr><a name="_details"></a><h2>Detailed Description</h2>
231M-ary <a class="el" href="classitpp_1_1QAM.html" title="M-ary QAM modulator with square lattice.">QAM</a> modulator with square lattice.
232<p>
233The size of the <a class="el" href="classitpp_1_1QAM.html" title="M-ary QAM modulator with square lattice.">QAM</a> constellation is <img class="formulaInl" alt="$M = 2^k$" src="form_256.png">, where <img class="formulaInl" alt="$k = 1, 2, \ldots $" src="form_257.png">. Symbol values in each dimension are: <img class="formulaInl" alt="$\{-(\sqrt{M}-1), \ldots, -3, -1, 1, 3, \ldots, (\sqrt{M}-1)\}$" src="form_258.png">. The bitmap is Gray encoded. Symbols are normalized so that the average energy is 1. That is, normalized with <img class="formulaInl" alt="$\sqrt{2(M-1)/3}$" src="form_259.png">.<p>
234Beside hard demapping, this class can also perform soft demodulation, calculating the log-MAP estimate of the individual bits. To use it properly the received symbols should be equal to: <p class="formulaDsp">
235<img class="formulaDsp" alt="\[r_k = c_k s_k + n_k,\]" src="form_252.png">
236<p>
237 where <img class="formulaInl" alt="$c_k$" src="form_253.png"> is the real or complex channel gain, <img class="formulaInl" alt="$s_k$" src="form_254.png"> is the transmitted constellation symbol, and <img class="formulaInl" alt="$n_k$" src="form_255.png"> is the AWGN of the channel (with variance <img class="formulaInl" alt="$N_0$" src="form_233.png">).<p>
238It is also assumed that the channel estimates are perfect when calculating the soft bits. <hr><h2>Member Function Documentation</h2>
239<a class="anchor" name="bd014d868b4f883712f92a7130401714"></a><!-- doxytag: member="itpp::QAM::demodulate_soft_bits" ref="bd014d868b4f883712f92a7130401714" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, const Vec&lt; std::complex&lt; double &gt; &gt; &amp;channel, double N0, vec &amp;soft_bits, Soft_Method method=LOGMAP) const" -->
240<div class="memitem">
241<div class="memproto">
242      <table class="memname">
243        <tr>
244          <td class="memname">virtual void <a class="el" href="classitpp_1_1Modulator.html">itpp::Modulator</a>&lt; std::complex&lt; double &gt;  &gt;::demodulate_soft_bits           </td>
245          <td>(</td>
246          <td class="paramtype">const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt;  &gt; &amp;&nbsp;</td>
247          <td class="paramname"> <em>rx_symbols</em>, </td>
248        </tr>
249        <tr>
250          <td class="paramkey"></td>
251          <td></td>
252          <td class="paramtype">const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt;  &gt; &amp;&nbsp;</td>
253          <td class="paramname"> <em>channel</em>, </td>
254        </tr>
255        <tr>
256          <td class="paramkey"></td>
257          <td></td>
258          <td class="paramtype">double&nbsp;</td>
259          <td class="paramname"> <em>N0</em>, </td>
260        </tr>
261        <tr>
262          <td class="paramkey"></td>
263          <td></td>
264          <td class="paramtype">vec &amp;&nbsp;</td>
265          <td class="paramname"> <em>soft_bits</em>, </td>
266        </tr>
267        <tr>
268          <td class="paramkey"></td>
269          <td></td>
270          <td class="paramtype"><a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a>&nbsp;</td>
271          <td class="paramname"> <em>method</em> = <code>LOGMAP</code></td><td>&nbsp;</td>
272        </tr>
273        <tr>
274          <td></td>
275          <td>)</td>
276          <td></td><td></td><td> const<code> [virtual, inherited]</code></td>
277        </tr>
278      </table>
279</div>
280<div class="memdoc">
281
282<p>
283Soft demodulator for fading channels.
284<p>
285This function calculates the log-likelihood ratio (LLR) of the received signal from fading channels. Depending on the soft demodulation method chosen, either full log-MAP calculation is performed (default method), according to the following equation: <p class="formulaDsp">
286<img class="formulaDsp" alt="\[\log \left( \frac{P(b_i=0|r)}{P(b_i=1|r)} \right) = \log \left( \frac{\sum_{s_i \in S_0} \exp \left( -\frac{|r_k - c_k s_i|^2}{N_0} \right)} {\sum_{s_i \in S_1} \exp \left( -\frac{|r_k - c_k s_i|^2}{N_0} \right)} \right) \]" src="form_275.png">
287<p>
288 or approximate, but faster calculation is performed.<p>
289The approximate method finds for each bit the closest constellation points that have zero and one in the corresponding position. Let <img class="formulaInl" alt="$d_0 = |r_k - c_k s_0|$" src="form_276.png"> denote the distance to the closest zero point and <img class="formulaInl" alt="$d_1 = |r_k - c_k s_1|$" src="form_277.png"> denote the distance to the closest one point for the corresponding bit respectively. The approximate algorithm then computes <p class="formulaDsp">
290<img class="formulaDsp" alt="\[\frac{d_1^2 - d_0^2}{N_0}\]" src="form_272.png">
291<p>
292<p>
293When this function is to be used together with MAP-based turbo decoding algorithms then the channel reliability factor <img class="formulaInl" alt="$L_c$" src="form_274.png"> of the turbo decoder shall be set to 1. The output from this function can also be used by a Viterbi decoder using an AWGN based metric calculation function.<p>
294<dl compact><dt><b>Parameters:</b></dt><dd>
295  <table border="0" cellspacing="2" cellpadding="0">
296    <tr><td valign="top"></td><td valign="top"><em>rx_symbols</em>&nbsp;</td><td>The received noisy constellation symbols <img class="formulaInl" alt="$r_k$" src="form_278.png"> </td></tr>
297    <tr><td valign="top"></td><td valign="top"><em>channel</em>&nbsp;</td><td>The channel values <img class="formulaInl" alt="$c_k$" src="form_253.png"> </td></tr>
298    <tr><td valign="top"></td><td valign="top"><em>N0</em>&nbsp;</td><td>The spectral density of the AWGN noise </td></tr>
299    <tr><td valign="top"></td><td valign="top"><em>soft_bits</em>&nbsp;</td><td>The soft bits calculated using the expression above </td></tr>
300    <tr><td valign="top"></td><td valign="top"><em>method</em>&nbsp;</td><td>The method used for demodulation (LOGMAP or APPROX)</td></tr>
301  </table>
302</dl>
303<dl class="note" compact><dt><b>Note:</b></dt><dd>For soft demodulation it is suggested to use the N-dimensional modulator (Modulator_ND) instead, which is based on the QLLR (quantized) arithmetic and therefore is faster. Please note, however, that mixed use of <code>Modulator_1D/<code>Modulator_2D</code> and</code> <code>Modulator_ND</code> is not advised. </dd></dl>
304
305</div>
306</div><p>
307<a class="anchor" name="9beffaf8f69378f9c20a85f3023bd9af"></a><!-- doxytag: member="itpp::QAM::demodulate_soft_bits" ref="9beffaf8f69378f9c20a85f3023bd9af" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;rx_symbols, double N0, vec &amp;soft_bits, Soft_Method method=LOGMAP) const" -->
308<div class="memitem">
309<div class="memproto">
310      <table class="memname">
311        <tr>
312          <td class="memname">virtual void <a class="el" href="classitpp_1_1Modulator.html">itpp::Modulator</a>&lt; std::complex&lt; double &gt;  &gt;::demodulate_soft_bits           </td>
313          <td>(</td>
314          <td class="paramtype">const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt;  &gt; &amp;&nbsp;</td>
315          <td class="paramname"> <em>rx_symbols</em>, </td>
316        </tr>
317        <tr>
318          <td class="paramkey"></td>
319          <td></td>
320          <td class="paramtype">double&nbsp;</td>
321          <td class="paramname"> <em>N0</em>, </td>
322        </tr>
323        <tr>
324          <td class="paramkey"></td>
325          <td></td>
326          <td class="paramtype">vec &amp;&nbsp;</td>
327          <td class="paramname"> <em>soft_bits</em>, </td>
328        </tr>
329        <tr>
330          <td class="paramkey"></td>
331          <td></td>
332          <td class="paramtype"><a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a>&nbsp;</td>
333          <td class="paramname"> <em>method</em> = <code>LOGMAP</code></td><td>&nbsp;</td>
334        </tr>
335        <tr>
336          <td></td>
337          <td>)</td>
338          <td></td><td></td><td> const<code> [virtual, inherited]</code></td>
339        </tr>
340      </table>
341</div>
342<div class="memdoc">
343
344<p>
345Soft demodulator for AWGN channels.
346<p>
347This function calculates the log-likelihood ratio (LLR) of the received signal from AWGN channels. Depending on the soft demodulation method chosen, either full log-MAP calculation is performed (default method), according to the following equation: <p class="formulaDsp">
348<img class="formulaDsp" alt="\[\log \left( \frac{P(b_i=0|r)}{P(b_i=1|r)} \right) = \log \left( \frac{\sum_{s_i \in S_0} \exp \left( -\frac{|r_k - s_i|^2}{N_0} \right)} {\sum_{s_i \in S_1} \exp \left( -\frac{|r_k - s_i|^2}{N_0} \right)} \right) \]" src="form_269.png">
349<p>
350 or approximate, but faster calculation is performed.<p>
351The approximate method finds for each bit the closest constellation points that have zero and one in the corresponding position. Let <img class="formulaInl" alt="$d_0 = |r_k - s_0|$" src="form_270.png"> denote the distance to the closest zero point and <img class="formulaInl" alt="$d_1 = |r_k - s_1|$" src="form_271.png"> denote the distance to the closest one point for the corresponding bit respectively. The approximate algorithm then computes <p class="formulaDsp">
352<img class="formulaDsp" alt="\[\frac{d_1^2 - d_0^2}{N_0}\]" src="form_272.png">
353<p>
354<p>
355This function can be used on channels where the channel gain <img class="formulaInl" alt="$c_k = 1$" src="form_273.png">.<p>
356When this function is to be used together with MAP-based turbo decoding algorithms then the channel reliability factor <img class="formulaInl" alt="$L_c$" src="form_274.png"> of the turbo decoder shall be set to 1. The output from this function can also be used by a Viterbi decoder using an AWGN based metric calculation function.<p>
357<dl compact><dt><b>Parameters:</b></dt><dd>
358  <table border="0" cellspacing="2" cellpadding="0">
359    <tr><td valign="top"></td><td valign="top"><em>rx_symbols</em>&nbsp;</td><td>The received noisy constellation symbols </td></tr>
360    <tr><td valign="top"></td><td valign="top"><em>N0</em>&nbsp;</td><td>The spectral density of the AWGN noise </td></tr>
361    <tr><td valign="top"></td><td valign="top"><em>soft_bits</em>&nbsp;</td><td>The soft bits calculated using the expression above </td></tr>
362    <tr><td valign="top"></td><td valign="top"><em>method</em>&nbsp;</td><td>The method used for demodulation (LOGMAP or APPROX)</td></tr>
363  </table>
364</dl>
365<dl class="note" compact><dt><b>Note:</b></dt><dd>For soft demodulation it is suggested to use the N-dimensional modulator (<code>Modulator_ND</code>) instead, which is based on the QLLR (quantized) arithmetic and therefore is faster. Please note, however, that mixed use of <code>Modulator_1D/<code>Modulator_2D</code> and</code> <code>Modulator_ND</code> is not advised. </dd></dl>
366
367</div>
368</div><p>
369<a class="anchor" name="a8186f0e837fd3d440a6acb7a0225d35"></a><!-- doxytag: member="itpp::QAM::get_bits2symbols" ref="a8186f0e837fd3d440a6acb7a0225d35" args="() const" -->
370<div class="memitem">
371<div class="memproto">
372      <table class="memname">
373        <tr>
374          <td class="memname">virtual ivec <a class="el" href="classitpp_1_1Modulator.html">itpp::Modulator</a>&lt; std::complex&lt; double &gt;  &gt;::get_bits2symbols           </td>
375          <td>(</td>
376          <td class="paramname">          </td>
377          <td>&nbsp;)&nbsp;</td>
378          <td> const<code> [inline, virtual, inherited]</code></td>
379        </tr>
380      </table>
381</div>
382<div class="memdoc">
383
384<p>
385Get the bitmap, which maps input bits into symbols.
386<p>
387The mapping is done as follows. An input bit sequence in decimal notation is used for indexing the <code>bits2symbols</code> table. The indexing result denotes the symbol to be used from the <code>symbols</code> table, e.g.:<p>
388<div class="fragment"><pre class="fragment"> PSK <a class="code" href="group__miscfunc.html#g441f466a2b056fe5f2b05fcd894c472f" title="Calculates the modulus, i.e. the signed reminder after division.">mod</a>(8); <span class="comment">// assume 8-PSK modulator</span>
389 cvec sym =  <a class="code" href="group__miscfunc.html#g441f466a2b056fe5f2b05fcd894c472f" title="Calculates the modulus, i.e. the signed reminder after division.">mod</a>.get_symbols();
390 ivec bits2sym = <a class="code" href="group__miscfunc.html#g441f466a2b056fe5f2b05fcd894c472f" title="Calculates the modulus, i.e. the signed reminder after division.">mod</a>.get_bits2symbols();
391 bvec in_bits = <span class="stringliteral">"100"</span> <span class="comment">// input bits</span>
392 <span class="keywordtype">int</span> d = <a class="code" href="group__convertfunc.html#g698adf78bc0f9d36fd5987bc87d543fa" title="Convert a bvec to decimal int with the first bit as MSB if msb_first == true.">bin2dec</a>(in_bits); <span class="comment">// decimal representation of in_bits = 4</span>
393 <span class="comment">// mapping of d into PSK symbol using bits2sym and sym tables</span>
394 std::complex&lt;double&gt; out_symbol = sym(bits2sym(d));
395</pre></div> 
396</div>
397</div><p>
398<hr>The documentation for this class was generated from the following files:<ul>
399<li><a class="el" href="modulator_8h-source.html">modulator.h</a><li><a class="el" href="modulator_8cpp.html">modulator.cpp</a></ul>
400</div>
401<hr size="1"><address style="text-align: right;"><small>Generated on Tue Jun 2 10:02:19 2009 for mixpp by&nbsp;
402<a href="http://www.doxygen.org/index.html">
403<img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.8 </small></address>
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