认知无线电网络中基于智能天线的空间频谱接入机会

摘要

认知无线电技术可以动态使用授权频段进行传输,因此如何有效利用这些频谱接入机会成为一个研究重点.研究了在认知无线电网络中使用智能天线,使认知用户在时域上获得频谱接入能力外,还具有增强的空间复用能力.当前频段出现活跃授权用户时,认知用户可以优化天线波束模式,避免干扰授权用户同时保持在该频段上的传输.对波束调节的策略进行了分析,并给出了使用这些策略时认知用户可以获得的空间共享概率.理论分析和仿真结果均表明,使用智能天线可以使认知用户获得更多的频谱接入机会,频段的利用率大幅提高.%The cognitive radio which could utilize spectrum holes to boost spectrum efficiency has garnered significant attention over the last few years.The cognitive radio network equipped with smart antennas further improved the spectrum efficiency in the spatial domain vertical to the schemes improving spectrum efficiency in the time domain.This paper argued that the cognitive users equipped with smart antennas could greatly improve spectrum efficiency by exploring spatial spectrum opportunities.With a smart antenna,a cognitive user could change the antenna pattern to avoid interference to primary users and maintain its communication without performing spectrum switching immediately.The paper investigated the statistical probability of the cognitive user utilizing the licensed channel with primary users concurrently.Both analytical and experimental results indicate that using smart antennas can greatly reduce the probability of spectrum switch and increase the spectrum efficiency in the spatial domain.