Spatial Domain Adaptive Transmission Based on Precoding in Cognitive MIMO System
Daming Wang, Shilei Zhu, Shuai Tang, Weijia Cui · Proceedings of the 2nd International Conference on Computer Science and Electronics Engineering (ICCSEE 2013) · 2013
In cognitive radio system, secondary users are difficult to obtain the CSI (channel state information) of the interference channel from the primary users which have absolute right of the spectrum sharing with secondary users due to the unlicensed utilization of spectrum resource.In order to guarantee the transparency of secondary transmission to primary transmission, a so-called "Detect-avoid" transmission mechanism is adopted in traditional cognitive radio system to avoid interference to primary user.However, it performs only in time-domain with inevitable underutilization of spectrum opportunities.In this paper, MIMO technique is introduced for secondary users to detect the real-time state information of the interference channel with its own cognitive capability and to a just the precoding matrix adaptively using the detection results, so that orthometric transmission with primary users in spatial domain is realized.Simulation result shows that the performance of the proposed algorithm without the knowledge of interference channel's CSI can approach to precoding algorithm based on perfect CSI.