http://wiki.jackslab.org/index.php?action=history&feed=atom&title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF 2026-05-06T10:07:37Z 本wiki的该页面的版本历史 MediaWiki 1.19.2 http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9828&oldid=prev 2018-09-12T09:12:43Z

<p>‎<span dir="auto"><span class="autocomment">Orthogonal Frequency</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 09:12的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第78行：</td> <td colspan="2" class="diff-lineno">第78行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 因为这种关系, 每个symbol传输时间内, 所有其他频率都跑完完整的n个周期, 总的干扰贡献为0. 信道之间无干扰, 不需要在子信道之间插入防止干扰的频率带.</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>* 因为这种关系, 每个symbol传输时间内, 所有其他频率都跑完完整的n个周期, 总的干扰贡献为0. 信道之间无干扰, 不需要在子信道之间插入防止干扰的频率带.</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>[[文件:Ofd-cacelation.jpg]]</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>[[文件:Ofd-cacelation.jpg<ins class="diffchange diffchange-inline">|800px</ins>]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td colspan="2" class="diff-lineno">第90行：</td> <td colspan="2" class="diff-lineno">第90行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://www.electronics-notes.com/articles/radio/multicarrier-modulation/ofdm-orthogonal-frequency-division-multiplexing-what-is-tutorial-basics.php&#160; OFDM basics]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://www.electronics-notes.com/articles/radio/multicarrier-modulation/ofdm-orthogonal-frequency-division-multiplexing-what-is-tutorial-basics.php&#160; OFDM basics]</div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====OFDM====</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====OFDM====</div></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9827&oldid=prev 2018-09-12T09:11:50Z

<p>‎<span dir="auto"><span class="autocomment">OFDM</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 09:11的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第64行：</td> <td colspan="2" class="diff-lineno">第64行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*OFDM/OFDMA</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*OFDM/OFDMA</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://en.wikipedia.org/wiki/Single-carrier_FDMA&#160; SC-FDMA]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://en.wikipedia.org/wiki/Single-carrier_FDMA&#160; SC-FDMA]</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">====Orthogonal Frequency====</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">什么是正交的频率.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">其实没有独立的正交频率, 正交频率出现在和一个固定周期的信号调制不同载波(不同频率), 如果载波的频率间隔满足一定条件, 就叫做一个正交子频率划分. 这个条件就是, 频率间隔等于调制信号周期的倒数. 调制信号一般是一个symbol, 比如QAM的symbol. 最后条件就变为, 频率间隔等于信号传输周期的倒数.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">这种频率间隔可以这样理解</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">* 因为这种关系, 每个symbol传输时间内, 所有其他频率都跑完完整的n个周期, 总的干扰贡献为0. 信道之间无干扰, 不需要在子信道之间插入防止干扰的频率带.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">[[文件:Ofd-cacelation.jpg]]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">* 因为这种关系, 每个信道的边带的0点都重和, 并且在其他信道的中心. 这是另一种理解正交划分无干扰的方式.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">[[文件:Ofdm_orthogonalspacedsubcarriers.png‎ ]]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">总之, 之所以无干扰, 数学上大概是这样的场景, 这样的调制, 就是一系列的乘法, 最后按照频率合并同类项的时候, 其他信道的信号的调制边带加起来都是0.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">*[https://www.electronics-notes.com/articles/radio/multicarrier-modulation/ofdm-orthogonal-frequency-division-multiplexing-what-is-tutorial-basics.php&#160; OFDM basics]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9822&oldid=prev 2018-09-12T06:47:04Z

<p>‎<span dir="auto"><span class="autocomment">SC-FDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 06:47的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第112行：</td> <td colspan="2" class="diff-lineno">第112行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-downlink-uplink.jpg‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-downlink-uplink.jpg‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>SC-FDMA叫单载波频分复用. 基本上是在OFDMA发射机前吧调制数据(QAM etc)变成时域波, 在进行FFT后分配到子信道上. 而不是直接拿QAM数据进行IFFT. <del class="diffchange diffchange-inline">最终的结果就是, 用户发送的信号是QAM的时域波调制了这个用户的上行载波.</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>SC-FDMA叫单载波频分复用. 基本上是在OFDMA发射机前吧调制数据(QAM etc)变成时域波, 在进行FFT后分配到子信道上. 而不是直接拿QAM数据进行IFFT.</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:Difference-between-SC-FDMA-and-OFDMA.jpg]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:Difference-between-SC-FDMA-and-OFDMA.jpg]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>&#160;</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">这样做的结果就是这个用户的上行子载波信道的强度不再是均匀的, 好像被constellation幅度调制了, 这样可以降低发射功耗,延长手机寿命,速度慢点儿.</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;">[[文件:SC-FDMA.jpg‎]]</del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td colspan="2" class="diff-lineno">第127行：</td> <td colspan="2" class="diff-lineno">第124行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[http://www.rfwireless-world.com/Articles/difference-between-SC-FDMA-and-OFDMA.html&#160; difference OFDM with SC-OFDM ]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[http://www.rfwireless-world.com/Articles/difference-between-SC-FDMA-and-OFDMA.html&#160; difference OFDM with SC-OFDM ]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[http://www.rfwireless-world.com/Articles/Difference_between_SC_and_OFDM.html&#160; SC vs OFDM]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[http://www.rfwireless-world.com/Articles/Difference_between_SC_and_OFDM.html&#160; SC vs OFDM]</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">*[http://ijettjournal.org/volume-12/number-2/IJETT-V12P214.pdf SC-FDMA &amp; OFDMA in LTE physical layer]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">*[http://arch.naist.jp/~hong/Lecture/Advanced_Cutting_Edge/Lecture_3.pdf MIMO OFDMA]</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 多工访问技术==</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>== 多工访问技术==</div></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9821&oldid=prev 2018-09-12T06:38:05Z

<p>‎<span dir="auto"><span class="autocomment">OFDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 06:38的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第98行：</td> <td colspan="2" class="diff-lineno">第98行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>相应的,<del class="diffchange diffchange-inline">发射机需要将不同用户的变成了多个OFDM单元</del>, <del class="diffchange diffchange-inline">并且有mapper负责分配子信道</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>相应的,<ins class="diffchange diffchange-inline">发射机需要将不同用户的constellation影射到不同的OFDM正交信道.下图没有明确指出多用户数据映射关系</ins>, <ins class="diffchange diffchange-inline">我全当那些并派的多箭头代表多个用户的数据.</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:OFDMA-transmitter.jpg]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:OFDMA-transmitter.jpg]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">可见,最后IFFT之后同一时刻在不同子载波包含多个用户的数据.</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[http://ijettjournal.org/volume-12/number-2/IJETT-V12P214.pdf&#160; SC-FDMA &amp; OFDMA in LTE physical layer]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[http://ijettjournal.org/volume-12/number-2/IJETT-V12P214.pdf&#160; SC-FDMA &amp; OFDMA in LTE physical layer]</div></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9820&oldid=prev 2018-09-12T06:33:23Z

<p>‎<span dir="auto"><span class="autocomment">OFDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 06:33的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第98行：</td> <td colspan="2" class="diff-lineno">第98行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>相应的,<del class="diffchange diffchange-inline">发射机结构也变成了多个OFDM单元</del>, 并且有mapper负责分配子信道</div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>相应的,<ins class="diffchange diffchange-inline">发射机需要将不同用户的变成了多个OFDM单元</ins>, 并且有mapper负责分配子信道</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:OFDMA-transmitter.jpg]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:OFDMA-transmitter.jpg]]</div></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9819&oldid=prev 2018-09-12T06:32:14Z

<p>‎<span dir="auto"><span class="autocomment">OFDM</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 06:32的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第69行：</td> <td colspan="2" class="diff-lineno">第69行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====OFDM====</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====OFDM====</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">一个OFDM发射机的逻辑框图如下(Wikipedia)</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">[[文件:OFDM transmitter ideal.png]]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">发送数据做了调制后(比如QAM), 被分配到到正交的子载波, 通过IFFT(频域到时域)转换出I/Q两个信号(同一个IFFT信号相差90度), 经过DAC, 与载波混频(也是相差90度的LO)得到发送信号. 这基本上就是SSB信号发射机一样的结构.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">实际上混频部分也可以数字化处理, 所以最终的实现可以数字直接IFFT输出OFDM基带信号,经过上变频发射. 下图是802.11的OFDM实现逻辑:</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:Ofdm_systemblockdiagram.png‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:Ofdm_systemblockdiagram.png‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:Ofdm_symbol_generation_.png‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:Ofdm_symbol_generation_.png‎]]</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://www.csie.ntu.edu.tw/~hsinmu/courses/_media/wn_11fall/ofdm_new.pdf&#160; OFDM台湾大学教程]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://www.csie.ntu.edu.tw/~hsinmu/courses/_media/wn_11fall/ofdm_new.pdf&#160; OFDM台湾大学教程]</div></td></tr> <tr><td colspan="2" class="diff-lineno">第80行：</td> <td colspan="2" class="diff-lineno">第90行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://en.wikipedia.org/wiki/Constellation_diagram OFDM Constellation]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://en.wikipedia.org/wiki/Constellation_diagram OFDM Constellation]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexing&#160; OFDM wikipedia]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>*[https://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexing&#160; OFDM wikipedia]</div></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;"></del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====OFDMA====</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====OFDMA====</div></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9817&oldid=prev 2018-09-12T06:02:05Z

<p>‎<span dir="auto"><span class="autocomment">SC-FDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 06:02的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第102行：</td> <td colspan="2" class="diff-lineno">第102行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-downlink-uplink.jpg‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-downlink-uplink.jpg‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>SC-FDMA叫单载波频分复用. <del class="diffchange diffchange-inline">基本上是在OFDM发射机前吧调制信号</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>SC-FDMA叫单载波频分复用. <ins class="diffchange diffchange-inline">基本上是在OFDMA发射机前吧调制数据(QAM etc)变成时域波, 在进行FFT后分配到子信道上. 而不是直接拿QAM数据进行IFFT. 最终的结果就是, 用户发送的信号是QAM的时域波调制了这个用户的上行载波.</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins class="diffchange diffchange-inline">[[文件:Difference-between-SC-FDMA-and-OFDMA.jpg]]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>&#160;</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;">接收机只需要吧子信道通过FFT取出, 进行解调制即可.</del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:SC-FDMA.jpg‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:SC-FDMA.jpg‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div><del style="color: red; font-weight: bold; text-decoration: none;">[[文件:Difference-between-SC-FDMA-and-OFDMA.jpg]]</del></div></td><td colspan="2">&#160;</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9816&oldid=prev 2018-09-12T05:54:58Z

<p>‎<span dir="auto"><span class="autocomment">SC-FDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 05:54的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第102行：</td> <td colspan="2" class="diff-lineno">第102行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-downlink-uplink.jpg‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-downlink-uplink.jpg‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>−</td><td style="background: #ffa; color:black; font-size: smaller;"><div>SC-FDMA叫单载波频分复用. <del class="diffchange diffchange-inline">单载波可以这样来理解: 上行就是一个用户在发送数据,因为没有别人了,但是你又不能随便用LTE的频率, 你得用分配给你的那一组子信道(连续12个)来发送信息,一个,比如QAM的constellation,你可以OFDMA到你这一组子信道,不过接收端呢要同时接收多个用户发送的信息, 又分布在不同的子信道组, 如果每个组子信道是单独的OFDMA形式, 接收机就会变成需要多组不一样配置的OFDMA接收机,这应该是完全不能接受的. 所以SC-FDMA, 让上行每个单独的用户吧自己的上行信道当成一个单独的频带(载波)来使用. 这样LTE上行结构就变成了下图的样子:</del></div></td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div>SC-FDMA叫单载波频分复用. <ins class="diffchange diffchange-inline">基本上是在OFDM发射机前吧调制信号</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9815&oldid=prev 2018-09-12T05:48:16Z

<p>‎<span dir="auto"><span class="autocomment">SC-FDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 05:48的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第106行：</td> <td colspan="2" class="diff-lineno">第106行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">接收机只需要吧子信道通过FFT取出, 进行解调制即可.</ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> </table>

Hyl http://wiki.jackslab.org/index.php?title=%E6%9D%82%E7%83%A9%E7%A7%BB%E5%8A%A8%E9%80%9A%E8%AE%AF&diff=9814&oldid=prev 2018-09-12T05:46:23Z

<p>‎<span dir="auto"><span class="autocomment">SC-FDMA</span></span></p> <table class='diff diff-contentalign-left'> <col class='diff-marker' /> <col class='diff-content' /> <col class='diff-marker' /> <col class='diff-content' /> <tr valign='top'> <td colspan='2' style="background-color: white; color:black;">←上一版本</td> <td colspan='2' style="background-color: white; color:black;">2018年9月12日 (三) 05:46的版本</td> </tr><tr><td colspan="2" class="diff-lineno">第97行：</td> <td colspan="2" class="diff-lineno">第97行：</td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====SC-FDMA====</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>====SC-FDMA====</div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">LTE中上下行复用技术不同, 下行是OFDMA, 上行是一个OFDMA的变种, SC-FDMA. </ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">[[文件:LTE-downlink-uplink.jpg‎]]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">SC-FDMA叫单载波频分复用. 单载波可以这样来理解: 上行就是一个用户在发送数据,因为没有别人了,但是你又不能随便用LTE的频率, 你得用分配给你的那一组子信道(连续12个)来发送信息,一个,比如QAM的constellation,你可以OFDMA到你这一组子信道,不过接收端呢要同时接收多个用户发送的信息, 又分布在不同的子信道组, 如果每个组子信道是单独的OFDMA形式, 接收机就会变成需要多组不一样配置的OFDMA接收机,这应该是完全不能接受的. 所以SC-FDMA, 让上行每个单独的用户吧自己的上行信道当成一个单独的频带(载波)来使用. 这样LTE上行结构就变成了下图的样子:</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;">[[文件:LTE-uplink-SC-FDMA_model.gif‎]]</ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td colspan="2">&#160;</td><td class='diff-marker'>+</td><td style="background: #cfc; color:black; font-size: smaller;"><div><ins style="color: red; font-weight: bold; text-decoration: none;"></ins></div></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"></td></tr> <tr><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:SC-FDMA.jpg‎]]</div></td><td class='diff-marker'>&#160;</td><td style="background: #eee; color:black; font-size: smaller;"><div>[[文件:SC-FDMA.jpg‎]]</div></td></tr> </table>

Hyl