标题: | 适用于多频带正交分频多工系统之通道及多微网衍生干扰对抗技术 Channel and Multi-Piconet Induced Interference Mitigation for Multi-band OFDM System |
作者: | 洪宗桦 Chung-Hua Hung 李大嵩 Ta-Sung Lee 电信工程研究所 |
关键字: | 多频带正交分频多工系统;超宽频系统;多微网;干扰;MB-OFDM;UWB;intercarrier;interference;SOP |
公开日期: | 2004 |
摘要: | 由于超宽频通讯系统具有取代家庭与办公室内高传输速率之有线系统的能力而成为极具潜能的新技术。超宽频技术可提供每秒数亿位元的传输速率而其涵盖的范围可达数公尺。IEEE802.15.3a多频段正交分频多工(Multiband OFDM, MB OFDM)系统是众多超宽频技术中较新的技术之一,该系统每次传输只利用500 MHz的频宽并且将该频宽分割成数个更小的副载波,然而MB OFDM之系统效能会受到长延迟扩散通道及多微网间干扰的影响而大幅下降。在本论文中,吾人提出一种具有对抗因长延迟扩散通道产生的载波间干扰(intercarrier interference)及避免其它微网(piconet)干扰之接收机,虽然最小均方差等化器可以改善此ICI问题,然而其复杂度过高不利于被MB OFDM所采用,因此吾人提出“载波间干扰消除辅助决策法”有效改善此一问题。另一方面,为了降低多微网间之干扰, MB OFDM采用四组时频交错码,吾人针对此问题提出“避免干扰传输法”,此方法略过被干扰的频槽(frequency slot),而只在不受干扰的频槽传输信号,藉以达到避免干扰之目的。吾人藉由电脑模拟验证上述架构在超宽频环境中可有效改善位元错误率。 Ultra wideband (UWB) communication is a potential new technique for replacing high-speed data cables in homes and offices. UWB technology will be capable of transmitting hundreds of megabits per second over distances of several meters. Multi-band (MB) orthogonal frequency division multiplexing (OFDM) system is one of the most innovative UWB techniques. MB OFDM system utilizes only 500 MHz instantaneous bandwidth and dividing that frequency band into smaller simultaneously transmitted subcarriers. In this thesis, a MB OFDM receiver is proposed, which mitigates the intercarrier interference (ICI) induced by a long delay spread channel and avoids the interference from other piconet, respectively. Performance of a MB OFDM system is typically significantly degraded due to long delay spread channels. Although the minimum mean-square error (MMSE) equalizer can solve this problem, the matrix inverse computation is too complex for the MB OFDM system. To alleviate this problem, the decision-aided ICI canceller is designed to improve the influence of ICI. On the other hand, the four unique time-frequency interleaving codes are adopted to reduce the effect of cochannel interference (CCI) from simultaneously operating piconets (SOP). Furthermore, we proposed an interference avoidance transmission scheme which turns off the collided frequency slots and conveys signal in the interference-free frequency slots. Finally, we evaluate the performance of the proposed system and confirm that it works well in a UWB environment. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT009213509 http://hdl.handle.net/11536/69501 |
显示于类别: | Thesis |
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