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67  <div class="navpath"><b>itpp</b>::<a class="el" href="classitpp_1_1PAM__c.html">PAM_c</a>
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70<div class="contents">
71<h1>itpp::PAM_c Class Reference<br>
72<small>
73[<a class="el" href="group__modulators.html">Digital Modulation</a>]</small>
74</h1><!-- doxytag: class="itpp::PAM_c" --><!-- doxytag: inherits="Modulator&lt; std::complex&lt; double &gt; &gt;" -->M-ary <a class="el" href="classitpp_1_1PAM.html" title="M-ary PAM modulator with real symbols.">PAM</a> modulator with complex symbols. 
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_1PAM__c-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="9bf8f8af7de4d55dc96b430179e22615"></a><!-- doxytag: member="itpp::PAM_c::PAM_c" ref="9bf8f8af7de4d55dc96b430179e22615" args="()" -->
85&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#9bf8f8af7de4d55dc96b430179e22615">PAM_c</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="ddf72f5ca262c86fb593c52a83ddd5a3"></a><!-- doxytag: member="itpp::PAM_c::PAM_c" ref="ddf72f5ca262c86fb593c52a83ddd5a3" args="(int M)" -->
89&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#ddf72f5ca262c86fb593c52a83ddd5a3">PAM_c</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">Constructor. <br></td></tr>
92<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="e1d8dee85093389be82470086df67797"></a><!-- doxytag: member="itpp::PAM_c::~PAM_c" ref="e1d8dee85093389be82470086df67797" args="()" -->
93virtual&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#e1d8dee85093389be82470086df67797">~PAM_c</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="5fdc1ce14d29d8d291dd23406904b606"></a><!-- doxytag: member="itpp::PAM_c::set_M" ref="5fdc1ce14d29d8d291dd23406904b606" args="(int M)" -->
97void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#5fdc1ce14d29d8d291dd23406904b606">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">Set the size of the signal constellation. <br></td></tr>
100<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="4254b3f8ca63e0a99fe83b1eeac22d2b"></a><!-- doxytag: member="itpp::PAM_c::demodulate_bits" ref="4254b3f8ca63e0a99fe83b1eeac22d2b" args="(const cvec &amp;signal, bvec &amp;output) const " -->
101void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#4254b3f8ca63e0a99fe83b1eeac22d2b">demodulate_bits</a> (const cvec &amp;signal, bvec &amp;output) const </td></tr>
102
103<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of <a class="el" href="classitpp_1_1PAM.html" title="M-ary PAM modulator with real symbols.">PAM</a> symbols in complex domain to bits. <br></td></tr>
104<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="95dc1aef180ef59c6140427827f6f076"></a><!-- doxytag: member="itpp::PAM_c::demodulate_bits" ref="95dc1aef180ef59c6140427827f6f076" args="(const cvec &amp;signal) const " -->
105bvec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#95dc1aef180ef59c6140427827f6f076">demodulate_bits</a> (const cvec &amp;signal) const </td></tr>
106
107<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of <a class="el" href="classitpp_1_1PAM.html" title="M-ary PAM modulator with real symbols.">PAM</a> symbols in complex domain to bits. <br></td></tr>
108<tr><td class="memItemLeft" nowrap align="right" valign="top">virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#56e1f1d20bfecdd0e5ef37456a5179ae">demodulate_soft_bits</a> (const cvec &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>
109
110<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for AWGN channels.  <a href="#56e1f1d20bfecdd0e5ef37456a5179ae"></a><br></td></tr>
111<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="c50d75d6d712a6809cab3170dac4cf0f"></a><!-- doxytag: member="itpp::PAM_c::demodulate_soft_bits" ref="c50d75d6d712a6809cab3170dac4cf0f" args="(const cvec &amp;rx_symbols, double N0, Soft_Method method=LOGMAP) const " -->
112virtual vec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#c50d75d6d712a6809cab3170dac4cf0f">demodulate_soft_bits</a> (const cvec &amp;rx_symbols, double N0, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const </td></tr>
113
114<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for AWGN channels. <br></td></tr>
115<tr><td class="memItemLeft" nowrap align="right" valign="top">virtual void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#6cd8dbe2ce99f63785cc51772e4e586d">demodulate_soft_bits</a> (const cvec &amp;rx_symbols, const cvec &amp;channel, double N0, vec &amp;soft_bits, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const </td></tr>
116
117<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for known fading channels.  <a href="#6cd8dbe2ce99f63785cc51772e4e586d"></a><br></td></tr>
118<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="ba7ea8361cec966f9a018980f77a2a74"></a><!-- doxytag: member="itpp::PAM_c::demodulate_soft_bits" ref="ba7ea8361cec966f9a018980f77a2a74" args="(const cvec &amp;rx_symbols, const cvec &amp;channel, double N0, Soft_Method method=LOGMAP) const " -->
119virtual vec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#ba7ea8361cec966f9a018980f77a2a74">demodulate_soft_bits</a> (const cvec &amp;rx_symbols, const cvec &amp;channel, double N0, <a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a> method=LOGMAP) const </td></tr>
120
121<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for known fading channels. <br></td></tr>
122<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="b9722a6826869c6d6e15a9835d76239b"></a><!-- doxytag: member="itpp::PAM_c::set" ref="b9722a6826869c6d6e15a9835d76239b" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;symbols, const ivec &amp;bits2symbols)" -->
123virtual 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>
124
125<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Set the constellation to use in the modulator. <br></td></tr>
126<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="6e7cfa06570e2a1de515be5222a53a83"></a><!-- doxytag: member="itpp::PAM_c::bits_per_symbol" ref="6e7cfa06570e2a1de515be5222a53a83" args="() const" -->
127virtual int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#6e7cfa06570e2a1de515be5222a53a83">bits_per_symbol</a> () const</td></tr>
128
129<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Returns number of bits per symbol. <br></td></tr>
130<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="28b1c28bf8f4596e4d5149f1f3c8cd76"></a><!-- doxytag: member="itpp::PAM_c::get_symbols" ref="28b1c28bf8f4596e4d5149f1f3c8cd76" args="() const" -->
131virtual <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex<br class="typebreak">
132&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>
133
134<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Get the symbol values used in the modulator. <br></td></tr>
135<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>
136
137<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>
138<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="4f7bde9d3bfa9e39c06017534e3f6647"></a><!-- doxytag: member="itpp::PAM_c::modulate" ref="4f7bde9d3bfa9e39c06017534e3f6647" args="(const ivec &amp;symbolnumbers, Vec&lt; std::complex&lt; double &gt; &gt; &amp;output) const" -->
139virtual 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>
140
141<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of symbols. <br></td></tr>
142<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="e0cb2673987e110920b519c139cdebe1"></a><!-- doxytag: member="itpp::PAM_c::modulate" ref="e0cb2673987e110920b519c139cdebe1" args="(const ivec &amp;symbolnumbers) const" -->
143virtual <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex<br class="typebreak">
144&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>
145
146<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of symbols. <br></td></tr>
147<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="845b5fbf4dad59edd3772627250623a1"></a><!-- doxytag: member="itpp::PAM_c::demodulate" ref="845b5fbf4dad59edd3772627250623a1" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal, ivec &amp;output) const" -->
148virtual 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>
149
150<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Demodulation of symbols. <br></td></tr>
151<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="7f2c15efa18d1cb46b8c97723c11ec9d"></a><!-- doxytag: member="itpp::PAM_c::demodulate" ref="7f2c15efa18d1cb46b8c97723c11ec9d" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal) const" -->
152virtual 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>
153
154<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Demodulation of symbols. <br></td></tr>
155<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="53826bf7e0ec83b99592235b0c2f6235"></a><!-- doxytag: member="itpp::PAM_c::modulate_bits" ref="53826bf7e0ec83b99592235b0c2f6235" args="(const bvec &amp;bits, Vec&lt; std::complex&lt; double &gt; &gt; &amp;output) const" -->
156virtual 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>
157
158<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of bits. <br></td></tr>
159<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="622fa1ce4243330b7efa0605a9492513"></a><!-- doxytag: member="itpp::PAM_c::modulate_bits" ref="622fa1ce4243330b7efa0605a9492513" args="(const bvec &amp;bits) const" -->
160virtual <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex<br class="typebreak">
161&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>
162
163<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Modulation of bits. <br></td></tr>
164<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="4d03bbe8bd467898f149d5f134f6f120"></a><!-- doxytag: member="itpp::PAM_c::demodulate_bits" ref="4d03bbe8bd467898f149d5f134f6f120" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal, bvec &amp;bits) const" -->
165virtual 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>
166
167<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of bits. <br></td></tr>
168<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="9e3432dad687ac0ee102c208e34920f8"></a><!-- doxytag: member="itpp::PAM_c::demodulate_bits" ref="9e3432dad687ac0ee102c208e34920f8" args="(const Vec&lt; std::complex&lt; double &gt; &gt; &amp;signal) const" -->
169virtual 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>
170
171<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Hard demodulation of bits. <br></td></tr>
172<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>
173
174<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for AWGN channels.  <a href="#9beffaf8f69378f9c20a85f3023bd9af"></a><br></td></tr>
175<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="a9cba88e460e11775fb72d21b543c375"></a><!-- doxytag: member="itpp::PAM_c::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" -->
176virtual 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>
177
178<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for AWGN channels. <br></td></tr>
179<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>
180
181<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for fading channels.  <a href="#bd014d868b4f883712f92a7130401714"></a><br></td></tr>
182<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="e40b7afd0d38d2d86b561b9dff6f55fd"></a><!-- doxytag: member="itpp::PAM_c::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" -->
183virtual 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>
184
185<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Soft demodulator for fading channels. <br></td></tr>
186<tr><td colspan="2"><br><h2>Protected Member Functions</h2></td></tr>
187<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="bb3e654a3fb6d127ee8d266677689233"></a><!-- doxytag: member="itpp::PAM_c::calculate_softbit_matrices" ref="bb3e654a3fb6d127ee8d266677689233" args="()" -->
188void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#bb3e654a3fb6d127ee8d266677689233">calculate_softbit_matrices</a> ()</td></tr>
189
190<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">This function calculates the soft bit mapping matrices S0 and S1. <br></td></tr>
191<tr><td colspan="2"><br><h2>Protected Attributes</h2></td></tr>
192<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="d654c2e53ee82b2279ab894b8801b980"></a><!-- doxytag: member="itpp::PAM_c::scaling_factor" ref="d654c2e53ee82b2279ab894b8801b980" args="" -->
193double&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1PAM__c.html#d654c2e53ee82b2279ab894b8801b980">scaling_factor</a></td></tr>
194
195<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Scaling factor used to normalize the average energy to 1. <br></td></tr>
196<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="552cd7add3e998eca485d0ea39808e0d"></a><!-- doxytag: member="itpp::PAM_c::setup_done" ref="552cd7add3e998eca485d0ea39808e0d" args="" -->
197bool&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#552cd7add3e998eca485d0ea39808e0d">setup_done</a></td></tr>
198
199<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Setup indicator. <br></td></tr>
200<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3656edc52486e0551b734b32ab67d3b6"></a><!-- doxytag: member="itpp::PAM_c::k" ref="3656edc52486e0551b734b32ab67d3b6" args="" -->
201int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#3656edc52486e0551b734b32ab67d3b6">k</a></td></tr>
202
203<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Number of bits per modulation symbol. <br></td></tr>
204<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="a434960c7ff9e5356d832aa53b46930b"></a><!-- doxytag: member="itpp::PAM_c::M" ref="a434960c7ff9e5356d832aa53b46930b" args="" -->
205int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#a434960c7ff9e5356d832aa53b46930b">M</a></td></tr>
206
207<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Number of modulation symbols. <br></td></tr>
208<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="1b1a9a706c0736c51966703bea58cf48"></a><!-- doxytag: member="itpp::PAM_c::bitmap" ref="1b1a9a706c0736c51966703bea58cf48" args="" -->
209<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>
210
211<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Bit to symbol mapping table (size: M x k). <br></td></tr>
212<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3ca26614189cb7a66da369bf0c4b9070"></a><!-- doxytag: member="itpp::PAM_c::bits2symbols" ref="3ca26614189cb7a66da369bf0c4b9070" args="" -->
213ivec&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#3ca26614189cb7a66da369bf0c4b9070">bits2symbols</a></td></tr>
214
215<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Bit to symbol mapping in decimal form (size: M). <br></td></tr>
216<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="3069840e9e7a44180615fb772cf9ae42"></a><!-- doxytag: member="itpp::PAM_c::symbols" ref="3069840e9e7a44180615fb772cf9ae42" args="" -->
217<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>
218
219<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Corresponding modulation symbols (size: M). <br></td></tr>
220<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="c19c8fe07e95e4eb80e832a633b7c422"></a><!-- doxytag: member="itpp::PAM_c::S0" ref="c19c8fe07e95e4eb80e832a633b7c422" args="" -->
221imat&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#c19c8fe07e95e4eb80e832a633b7c422">S0</a></td></tr>
222
223<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>
224<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="9d4c223ffd96fdc5b26ba5c44956998b"></a><!-- doxytag: member="itpp::PAM_c::S1" ref="9d4c223ffd96fdc5b26ba5c44956998b" args="" -->
225imat&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="classitpp_1_1Modulator.html#9d4c223ffd96fdc5b26ba5c44956998b">S1</a></td></tr>
226
227<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>
228<tr><td colspan="2"><br><h2>Related Functions</h2></td></tr>
229<tr><td colspan="2">(Note that these are not member functions.) <br><br></td></tr>
230<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="d47d1377dffb2aed9f21f8f976e80a0a"></a><!-- doxytag: member="itpp::PAM_c::Modulator_1D" ref="d47d1377dffb2aed9f21f8f976e80a0a" args="" -->
231typedef <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>
232
233<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Definition of 1D Modulator (with real symbols). <br></td></tr>
234<tr><td class="memItemLeft" nowrap align="right" valign="top"><a class="anchor" name="97dc4e87ae4fa63c4e7dbbeac0ab00b0"></a><!-- doxytag: member="itpp::PAM_c::Modulator_2D" ref="97dc4e87ae4fa63c4e7dbbeac0ab00b0" args="" -->
235typedef <a class="el" href="classitpp_1_1Modulator.html">Modulator</a><br class="typebreak">
236&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>
237
238<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Definition of 2D Modulator (with complex symbols). <br></td></tr>
239</table>
240<hr><a name="_details"></a><h2>Detailed Description</h2>
241M-ary <a class="el" href="classitpp_1_1PAM.html" title="M-ary PAM modulator with real symbols.">PAM</a> modulator with complex symbols.
242<p>
243This class implements an M-ary <a class="el" href="classitpp_1_1PAM.html" title="M-ary PAM modulator with real symbols.">PAM</a> modulator with the following signal values: <img class="formulaInl" alt="$\{-(M-1), \ldots, -3, -1, 1, 3, \ldots, (M-1)\}$" src="form_267.png">. Symbol numbering is from right to left in the increasing order. The Gray encoding of bits to symbols is used.<p>
244The constellation symbols are normalized so that the average energy is equal to 1. That is, normalized with <img class="formulaInl" alt="$ \sqrt{(M^2-1)/3}$" src="form_268.png">.<p>
245<dl class="note" compact><dt><b>Note:</b></dt><dd>Although the constellation points can be represented in the real domain only, this class uses complex based interface to be compatible with other <a class="el" href="classitpp_1_1PSK.html" title="M-ary PSK modulator.">PSK</a> and <a class="el" href="classitpp_1_1QAM.html" title="M-ary QAM modulator with square lattice.">QAM</a> based modulators.</dd></dl>
246<dl class="see" compact><dt><b>See also:</b></dt><dd><a class="el" href="classitpp_1_1PAM.html" title="M-ary PAM modulator with real symbols.">PAM</a> </dd></dl>
247<hr><h2>Member Function Documentation</h2>
248<a class="anchor" name="bd014d868b4f883712f92a7130401714"></a><!-- doxytag: member="itpp::PAM_c::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" -->
249<div class="memitem">
250<div class="memproto">
251      <table class="memname">
252        <tr>
253          <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>
254          <td>(</td>
255          <td class="paramtype">const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt;  &gt; &amp;&nbsp;</td>
256          <td class="paramname"> <em>rx_symbols</em>, </td>
257        </tr>
258        <tr>
259          <td class="paramkey"></td>
260          <td></td>
261          <td class="paramtype">const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt;  &gt; &amp;&nbsp;</td>
262          <td class="paramname"> <em>channel</em>, </td>
263        </tr>
264        <tr>
265          <td class="paramkey"></td>
266          <td></td>
267          <td class="paramtype">double&nbsp;</td>
268          <td class="paramname"> <em>N0</em>, </td>
269        </tr>
270        <tr>
271          <td class="paramkey"></td>
272          <td></td>
273          <td class="paramtype">vec &amp;&nbsp;</td>
274          <td class="paramname"> <em>soft_bits</em>, </td>
275        </tr>
276        <tr>
277          <td class="paramkey"></td>
278          <td></td>
279          <td class="paramtype"><a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a>&nbsp;</td>
280          <td class="paramname"> <em>method</em> = <code>LOGMAP</code></td><td>&nbsp;</td>
281        </tr>
282        <tr>
283          <td></td>
284          <td>)</td>
285          <td></td><td></td><td> const<code> [virtual, inherited]</code></td>
286        </tr>
287      </table>
288</div>
289<div class="memdoc">
290
291<p>
292Soft demodulator for fading channels.
293<p>
294This 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">
295<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">
296<p>
297 or approximate, but faster calculation is performed.<p>
298The 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">
299<img class="formulaDsp" alt="\[\frac{d_1^2 - d_0^2}{N_0}\]" src="form_272.png">
300<p>
301<p>
302When 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>
303<dl compact><dt><b>Parameters:</b></dt><dd>
304  <table border="0" cellspacing="2" cellpadding="0">
305    <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>
306    <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>
307    <tr><td valign="top"></td><td valign="top"><em>N0</em>&nbsp;</td><td>The spectral density of the AWGN noise </td></tr>
308    <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>
309    <tr><td valign="top"></td><td valign="top"><em>method</em>&nbsp;</td><td>The method used for demodulation (LOGMAP or APPROX)</td></tr>
310  </table>
311</dl>
312<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>
313
314</div>
315</div><p>
316<a class="anchor" name="9beffaf8f69378f9c20a85f3023bd9af"></a><!-- doxytag: member="itpp::PAM_c::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" -->
317<div class="memitem">
318<div class="memproto">
319      <table class="memname">
320        <tr>
321          <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>
322          <td>(</td>
323          <td class="paramtype">const <a class="el" href="classitpp_1_1Vec.html">Vec</a>&lt; std::complex&lt; double &gt;  &gt; &amp;&nbsp;</td>
324          <td class="paramname"> <em>rx_symbols</em>, </td>
325        </tr>
326        <tr>
327          <td class="paramkey"></td>
328          <td></td>
329          <td class="paramtype">double&nbsp;</td>
330          <td class="paramname"> <em>N0</em>, </td>
331        </tr>
332        <tr>
333          <td class="paramkey"></td>
334          <td></td>
335          <td class="paramtype">vec &amp;&nbsp;</td>
336          <td class="paramname"> <em>soft_bits</em>, </td>
337        </tr>
338        <tr>
339          <td class="paramkey"></td>
340          <td></td>
341          <td class="paramtype"><a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a>&nbsp;</td>
342          <td class="paramname"> <em>method</em> = <code>LOGMAP</code></td><td>&nbsp;</td>
343        </tr>
344        <tr>
345          <td></td>
346          <td>)</td>
347          <td></td><td></td><td> const<code> [virtual, inherited]</code></td>
348        </tr>
349      </table>
350</div>
351<div class="memdoc">
352
353<p>
354Soft demodulator for AWGN channels.
355<p>
356This 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">
357<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">
358<p>
359 or approximate, but faster calculation is performed.<p>
360The 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">
361<img class="formulaDsp" alt="\[\frac{d_1^2 - d_0^2}{N_0}\]" src="form_272.png">
362<p>
363<p>
364This function can be used on channels where the channel gain <img class="formulaInl" alt="$c_k = 1$" src="form_273.png">.<p>
365When 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>
366<dl compact><dt><b>Parameters:</b></dt><dd>
367  <table border="0" cellspacing="2" cellpadding="0">
368    <tr><td valign="top"></td><td valign="top"><em>rx_symbols</em>&nbsp;</td><td>The received noisy constellation symbols </td></tr>
369    <tr><td valign="top"></td><td valign="top"><em>N0</em>&nbsp;</td><td>The spectral density of the AWGN noise </td></tr>
370    <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>
371    <tr><td valign="top"></td><td valign="top"><em>method</em>&nbsp;</td><td>The method used for demodulation (LOGMAP or APPROX)</td></tr>
372  </table>
373</dl>
374<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>
375
376</div>
377</div><p>
378<a class="anchor" name="6cd8dbe2ce99f63785cc51772e4e586d"></a><!-- doxytag: member="itpp::PAM_c::demodulate_soft_bits" ref="6cd8dbe2ce99f63785cc51772e4e586d" args="(const cvec &amp;rx_symbols, const cvec &amp;channel, double N0, vec &amp;soft_bits, Soft_Method method=LOGMAP) const " -->
379<div class="memitem">
380<div class="memproto">
381      <table class="memname">
382        <tr>
383          <td class="memname">void itpp::PAM_c::demodulate_soft_bits           </td>
384          <td>(</td>
385          <td class="paramtype">const cvec &amp;&nbsp;</td>
386          <td class="paramname"> <em>rx_symbols</em>, </td>
387        </tr>
388        <tr>
389          <td class="paramkey"></td>
390          <td></td>
391          <td class="paramtype">const cvec &amp;&nbsp;</td>
392          <td class="paramname"> <em>channel</em>, </td>
393        </tr>
394        <tr>
395          <td class="paramkey"></td>
396          <td></td>
397          <td class="paramtype">double&nbsp;</td>
398          <td class="paramname"> <em>N0</em>, </td>
399        </tr>
400        <tr>
401          <td class="paramkey"></td>
402          <td></td>
403          <td class="paramtype">vec &amp;&nbsp;</td>
404          <td class="paramname"> <em>soft_bits</em>, </td>
405        </tr>
406        <tr>
407          <td class="paramkey"></td>
408          <td></td>
409          <td class="paramtype"><a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a>&nbsp;</td>
410          <td class="paramname"> <em>method</em> = <code>LOGMAP</code></td><td>&nbsp;</td>
411        </tr>
412        <tr>
413          <td></td>
414          <td>)</td>
415          <td></td><td></td><td> const<code> [virtual]</code></td>
416        </tr>
417      </table>
418</div>
419<div class="memdoc">
420
421<p>
422Soft demodulator for known fading channels.
423<p>
424This 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">
425<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">
426<p>
427 or approximate, but faster calculation is performed.<p>
428The 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">
429<img class="formulaDsp" alt="\[\frac{d_1^2 - d_0^2}{N_0}\]" src="form_272.png">
430<p>
431<p>
432When 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>
433<dl compact><dt><b>Parameters:</b></dt><dd>
434  <table border="0" cellspacing="2" cellpadding="0">
435    <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"> (complex) </td></tr>
436    <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>
437    <tr><td valign="top"></td><td valign="top"><em>N0</em>&nbsp;</td><td>The spectral density of the AWGN noise </td></tr>
438    <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>
439    <tr><td valign="top"></td><td valign="top"><em>method</em>&nbsp;</td><td>The method used for demodulation (LOGMAP or APPROX)</td></tr>
440  </table>
441</dl>
442<dl class="note" compact><dt><b>Note:</b></dt><dd>For soft demodulation it is suggested to use the N-dimensional modulator (<a class="el" href="classitpp_1_1Modulator__ND.html" title="Base class for an N-dimensional (ND) vector (MIMO) modulator.">Modulator_ND</a>) 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><a class="el" href="classitpp_1_1Modulator__ND.html" title="Base class for an N-dimensional (ND) vector (MIMO) modulator.">Modulator_ND</a></code> is not advised. </dd></dl>
443
444<p>References <a class="el" href="log__exp_8h-source.html#l00172">itpp::exp()</a>, <a class="el" href="itassert_8h-source.html#l00107">it_assert_debug</a>, <a class="el" href="modulator_8h-source.html#l00228">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::k</a>, <a class="el" href="modulator_8h-source.html#l00047">itpp::LOGMAP</a>, <a class="el" href="modulator_8h-source.html#l00230">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::M</a>, <a class="el" href="tcp_8h-source.html#l00117">itpp::max()</a>, <a class="el" href="fix__functions_8cpp-source.html#l00084">itpp::real()</a>, <a class="el" href="modulator_8h-source.html#l00239">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::S0</a>, <a class="el" href="modulator_8h-source.html#l00242">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::S1</a>, <a class="el" href="modulator_8h-source.html#l00226">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::setup_done</a>, <a class="el" href="elem__math_8h-source.html#l00056">itpp::sqr()</a>, <a class="el" href="modulator_8h-source.html#l00236">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::symbols</a>, and <a class="el" href="log__exp_8h-source.html#l00105">itpp::trunc_log()</a>.</p>
445
446</div>
447</div><p>
448<a class="anchor" name="56e1f1d20bfecdd0e5ef37456a5179ae"></a><!-- doxytag: member="itpp::PAM_c::demodulate_soft_bits" ref="56e1f1d20bfecdd0e5ef37456a5179ae" args="(const cvec &amp;rx_symbols, double N0, vec &amp;soft_bits, Soft_Method method=LOGMAP) const " -->
449<div class="memitem">
450<div class="memproto">
451      <table class="memname">
452        <tr>
453          <td class="memname">void itpp::PAM_c::demodulate_soft_bits           </td>
454          <td>(</td>
455          <td class="paramtype">const cvec &amp;&nbsp;</td>
456          <td class="paramname"> <em>rx_symbols</em>, </td>
457        </tr>
458        <tr>
459          <td class="paramkey"></td>
460          <td></td>
461          <td class="paramtype">double&nbsp;</td>
462          <td class="paramname"> <em>N0</em>, </td>
463        </tr>
464        <tr>
465          <td class="paramkey"></td>
466          <td></td>
467          <td class="paramtype">vec &amp;&nbsp;</td>
468          <td class="paramname"> <em>soft_bits</em>, </td>
469        </tr>
470        <tr>
471          <td class="paramkey"></td>
472          <td></td>
473          <td class="paramtype"><a class="el" href="group__modulators.html#g5128af4688e1a1caa84e1fabf051faa7">Soft_Method</a>&nbsp;</td>
474          <td class="paramname"> <em>method</em> = <code>LOGMAP</code></td><td>&nbsp;</td>
475        </tr>
476        <tr>
477          <td></td>
478          <td>)</td>
479          <td></td><td></td><td> const<code> [virtual]</code></td>
480        </tr>
481      </table>
482</div>
483<div class="memdoc">
484
485<p>
486Soft demodulator for AWGN channels.
487<p>
488This 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">
489<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">
490<p>
491 or approximate, but faster calculation is performed.<p>
492The 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">
493<img class="formulaDsp" alt="\[\frac{d_1^2 - d_0^2}{N_0}\]" src="form_272.png">
494<p>
495<p>
496This function can be used on channels where the channel gain <img class="formulaInl" alt="$c = 1$" src="form_288.png">.<p>
497When 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>
498<dl compact><dt><b>Parameters:</b></dt><dd>
499  <table border="0" cellspacing="2" cellpadding="0">
500    <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"> (complex, but symbols are real) </td></tr>
501    <tr><td valign="top"></td><td valign="top"><em>N0</em>&nbsp;</td><td>The spectral density of the AWGN noise </td></tr>
502    <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>
503    <tr><td valign="top"></td><td valign="top"><em>method</em>&nbsp;</td><td>The method used for demodulation (LOGMAP or APPROX)</td></tr>
504  </table>
505</dl>
506<dl class="note" compact><dt><b>Note:</b></dt><dd>For soft demodulation it is suggested to use the N-dimensional modulator (<a class="el" href="classitpp_1_1Modulator__ND.html" title="Base class for an N-dimensional (ND) vector (MIMO) modulator.">Modulator_ND</a>) 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><a class="el" href="classitpp_1_1Modulator__ND.html" title="Base class for an N-dimensional (ND) vector (MIMO) modulator.">Modulator_ND</a></code> is not advised. </dd></dl>
507
508<p>References <a class="el" href="log__exp_8h-source.html#l00172">itpp::exp()</a>, <a class="el" href="itassert_8h-source.html#l00107">it_assert_debug</a>, <a class="el" href="modulator_8h-source.html#l00228">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::k</a>, <a class="el" href="modulator_8h-source.html#l00047">itpp::LOGMAP</a>, <a class="el" href="modulator_8h-source.html#l00230">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::M</a>, <a class="el" href="tcp_8h-source.html#l00117">itpp::max()</a>, <a class="el" href="fix__functions_8cpp-source.html#l00084">itpp::real()</a>, <a class="el" href="modulator_8h-source.html#l00239">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::S0</a>, <a class="el" href="modulator_8h-source.html#l00242">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::S1</a>, <a class="el" href="modulator_8h-source.html#l00226">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::setup_done</a>, <a class="el" href="elem__math_8h-source.html#l00056">itpp::sqr()</a>, <a class="el" href="modulator_8h-source.html#l00236">itpp::Modulator&lt; std::complex&lt; double &gt; &gt;::symbols</a>, and <a class="el" href="log__exp_8h-source.html#l00105">itpp::trunc_log()</a>.</p>
509
510<p>Referenced by <a class="el" href="modulator_8cpp-source.html#l00474">demodulate_soft_bits()</a>.</p>
511
512</div>
513</div><p>
514<a class="anchor" name="a8186f0e837fd3d440a6acb7a0225d35"></a><!-- doxytag: member="itpp::PAM_c::get_bits2symbols" ref="a8186f0e837fd3d440a6acb7a0225d35" args="() const" -->
515<div class="memitem">
516<div class="memproto">
517      <table class="memname">
518        <tr>
519          <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>
520          <td>(</td>
521          <td class="paramname">          </td>
522          <td>&nbsp;)&nbsp;</td>
523          <td> const<code> [inline, virtual, inherited]</code></td>
524        </tr>
525      </table>
526</div>
527<div class="memdoc">
528
529<p>
530Get the bitmap, which maps input bits into symbols.
531<p>
532The 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>
533<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>
534 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();
535 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();
536 bvec in_bits = <span class="stringliteral">"100"</span> <span class="comment">// input bits</span>
537 <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>
538 <span class="comment">// mapping of d into PSK symbol using bits2sym and sym tables</span>
539 std::complex&lt;double&gt; out_symbol = sym(bits2sym(d));
540</pre></div> 
541</div>
542</div><p>
543<hr>The documentation for this class was generated from the following files:<ul>
544<li><a class="el" href="modulator_8h-source.html">modulator.h</a><li><a class="el" href="modulator_8cpp.html">modulator.cpp</a></ul>
545</div>
546<hr size="1"><address style="text-align: right;"><small>Generated on Tue Jun 2 10:02:19 2009 for mixpp by&nbsp;
547<a href="http://www.doxygen.org/index.html">
548<img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.8 </small></address>
549</body>
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