A Simple, High-Performance Space–Time Code for MIMO Backscatter Communications

In this article, we propose a $2 \times 2$ space–time code (STC) for backscatter communications. The interesting thing is that although the proposed code performs much worse than the classical Alamouti code in conventional channels, it achieves almost the same performance as the Alamouti code in backscatter channels. More importantly, it has a considerably lower tag circuit complexity, which is more preferred in hardware-limited backscatter devices. This article indicates that the sets of “good STCs” for conventional channels and backscatter channels are not heavily overlapped, and there may exist many simpler STCs, which were previously ignored and not reported in conventional channels, have high performance, particularly, in backscatter channels.