We consider an opportunistic cognitive radio (CR) system in which secondary transmitter (SU _tx ) is equipped with a reconfigurable antenna (RA). Utilizing the beam steering capability of the RA, we regard a design framework for integrated sector-based spectrum sensing and data communication. In this framework, SU _tx senses the spectrum and detects the beam corresponding to active primary user’s (PU) location. SU _tx also sends training symbols (prior to data symbols), to enable channel estimation at secondary receiver (SU _rx ) and selection of the strongest beam between SU _tx – SU _rx for data transmission. We establish a lower bound on the achievable rates of SU _tx – SU _rx link, in the presence of spectrum sensing and channel estimation errors, and errors due to incorrect detection of the beam corresponding to PU’s location and incorrect selection of the strongest beam for data transmission. We formulate a novel constrained optimization problem, aiming at maximizing the derived achievable rate lower bound subject to average transmit and interference power constraints. We optimize the durations of spatial spectrum sensing and channel training as well as data symbol transmission power. Our numerical results demonstrate that between optimizing spectrum sensing and channel training durations, the latter is more important for providing higher achievable rates.

中文翻译：

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使用具有不完美感测和信道估计的可重构天线的机会主义认知无线电系统的可实现速率

我们考虑一个机会主义认知无线电 (CR) 系统，其中辅助发射机 (SU _tx ) 配备了可重构天线 (RA)。利用 RA 的波束控制能力，我们考虑了基于扇区的集成频谱感知和数据通信的设计框架。在此框架中，SU _tx感测频谱并检测对应于活动主用户 (PU) 位置的波束。SU _tx还发送训练符号（在数据符号之前），以启用辅助接收器 (SU _rx ) 的信道估计 和选择 SU _tx – SU _rx之间的最强波束 以进行数据传输。我们建立了 SU _tx可实现速率的下限 – SU _rx链路，存在频谱感知和信道估计错误，以及由于不正确检测对应于 PU 位置的波束和不正确选择用于数据传输的最强波束而导致的错误。我们制定了一个新的约束优化问题，旨在最大化受平均传输和干扰功率约束的导出的可实现速率下限。我们优化了空间频谱感知和信道训练的持续时间以及数据符号传输功率。我们的数值结果表明，在优化频谱感知和信道训练持续时间之间，后者对于提供更高的可实现速率更为重要。