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学术讲座通知题目：Hybrid Overlay/Underlay Waveform Design for Soft-Decision Cognitive Radio(基于软决策认知无线电的混合Overlay和Underlay波形设计) 主讲人：Zhiqiang Wu, Ph.D. (Associate Professor, Department of Electrical Engineering, Wright State University) 时间：2010年3月25日（星期四）下午2：30 地点：校办公楼501报告厅摘要：Spectrum Congestion is a concern to both military and commercial applications. Recent studies have suggested that spectrum congestion is mainly due to the inefficient use of spectrum rather than its unavailability. Currently there are two kinds of cognitive radio: overlay cognitive radio and underlay cognitive radio. In overlay cognitive radio, secondary users harness unused spectrum bands (spectrum holes) for their transmission; in underlay cognitive radio, an ultra-wideband transmission with very low power spectrum density is employed by the secondary user to minimize harmful interference to the primary users. We have proposed and implemented a hybrid overlay/underlay cognitive radio to take advantage of both groups. In the proposed soft-decision cognitive radio, secondary users transmit over both unused spectrum bands and under-used spectrum bands to maximize its throughput, while maintaining only tolerable interference to the primary users in the same spectrum. Using Spectrally Modulated Spectrally Encoded (SMSE) framework, we design the hybrid overlay/underlay waveforms for the cognitive radio and show its performance gain over current cognitive radio systems. Furthermore, employing USRP software defined radio boards, we implement a real time video transmission over the proposed cognitive radio node. (频谱拥塞是一个长期以来一直困扰无线通信工程师的重要问题。各国的频谱管理体制基本上都沿用美国联邦通讯委员会制定的固定频谱分配体制。近来的很多研究和测量表明，频谱拥塞重要是由频谱分配和使用的低效率导致的。认知无线电和动态频谱接入网络因此应运而生，成为近期无线通信和网络研究的热点。通常的认知无线电技术主要采用两种频谱接入方式：Overlay和Underlay。在基于Overlay的系统中，认知无线电用户检测未使用的频段（又称频率洞）并使用这些频段传输信息。在基于Underlay的系统中，认知无线电用户采用一个功率谱很低的超宽带信号来传输信息以避免对主用户的干扰。我们提出了一个新型的认知无线电方案，该方案同时在未使用频段和未充分使用的频段上传输。这个名为软决策认知无线电的新方案能够在避免对主用户的干扰的同时，最大化认知无线电用户的传输性能。我们将讨论基于SMSE框架下针对该方案的波形设计和性能估计。最后，我们还采用软件无线电实现了这一新型方案，并能够演示一个实时的软决策认知无线电支持下的视频传输。) 此报告为前沿讲座，可以盖章，欢迎全校师生踊跃参加。校学术委员会 2010年3月19日 -------------------------------------------------------------------------------- 返回