基于空时块编码和正交脉冲的MIMO系统性能研究

为了有效利用脉冲无线电(IR)的短距离、高数据速率以及多输入多输出(MIMO)通信系统的更大容量,提出了一种基于空时块编码(STBC)和正交脉冲的MIMO超宽带(UWB)通信系统。具体实现是通过对标准单输入单输出(SISO)脉冲无线电系统的直接序列超宽带作为多址(MA)技术的IR-MA信号模型以及信道模型、收发器结构和检测方法的分析,提出了一种把空时块编码和正交脉冲相结合的新方法,并采用FS-rake相干接收(CR)和非相干接收(NCR)技术及IEEE UWB信道模型对其获得的空间分集和编码性能进行了研究,从而得到可以相对较好地描述高信噪比时的性能变化趋势的理论上限值。仿真结果表明,这种STBC-IR方案相比于传统的单链路-脉冲无线电(SL-IR)方案,可获得更好的空间分集和编码增益,可用于增加传输距离和减少rake接收机的复杂性,而且在UWB通信中,STBC-IR方案还能很好地消除定时抖动的影响。     

On the performance and strategy of innovation systems: A multicriteria group decision analysis approach

Mainstream approaches to analyzing innovation systems are based on statistical methods, use standard sets of indicators, and are typically deployed to measure and classify innovation performance. As they are not based on decision-theoretic approaches that involve the multiple agents that are usually embedded in innovation systems, conventional approaches are rather inadequate to generate the strategy and describe the dynamics of innovation systems. Taking a rather different approach that has been motivated by the need to generate the strategy of innovation systems, we set out a methodology that lies at the intersection of strategy, innovation and decision theory. The methodology construes the strategy of an innovation system as a process that emerges from the evaluations of agents and the aggregation logics used to arrive at a group decision. The methodology draws upon the TOPSIS multicriteria decision analysis method, uses the Mahalanobis metric of distance and applies the Borda count to aggregate the preferences of multiple agents who participate as strategists in the process of allocating resources based on a set of agreed-upon indicators. The resulting methodology can be used in concert with different innovation frameworks using sets of indicators that may show varying degrees of correlation in order to drive the strategy of innovation systems as a dynamic group decision-theoretic process.