认知无线电系统对TD-LTE主用户系统上下行配置类型的识别

当与时分双工主用户系统共存时，认知无线电系统首先需要识别主用户系统在时间尺度上的传输方向，以便在不同链路上分别设计与执行后续的认知过程，从而优化认知系统的性能。在目前的研究中，均假设认知系统已先验已知主用户系统上下行链路在时间上的交替规律。在普适的认知场景下，该假设并不实际。该文依据双工通信系统上下行发射功率的差异，提出对TD-LTE主用户系统在时间尺度上传输方向的识别算法；基于此初步识别结果，进一步提出对TD-LTE系统上下行配置类型的识别算法。该方法无需主次系统之间的信息交互，实现简单。仿真表明，通过数个次级用户观察10个左右的TD-LTE帧，即可对其上下行配置类型达到95%以上的识别精度。

Downlink/uplink Configuration Identification of TD-LTE Primary Systems in Cognitive Radios

When the cognitive radios are coexisting with time division duplex systems, it should firstly find out the link directions of the primary systems for the separate design and implementation of the followed spectrum sensing and access. However, in the present studies, this information is assumed as prior information of the cognitive radios, which in fact is not practical in common scenarios. In this paper, a method based on the power levels on both links of TD-LTE is proposed to identify the link directions of subframes and the downlink/uplink configuration in the TD-LTE. This method needs not the cooperation between the primary and secondary systems. Simulations show that the method can meet a high accuracy when a few of frames and SUs are participated in the identification.