Detection-Localization Tradeoff in MIMO Radars

Two gains play key roles in recently developed MIMO wireless communication systems: “spatial diversity” gain and “spatial multiplexing” gain. The diversity gain refers to the capability to decrease the error rate of theMIMO channel, while the multiplexing gain implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance the system’s performance. As a MIMO system, it is expected that the mentioned diversity-multiplexing tradeoff exists in a MIMO radar, too. In this paper, this tradeoff is studied and verified in MIMO radars with widely separated antennas. In more details, it will be shown that increasing dependency between transmit-receive links results in higher diversity gain and lower multiplexing gain, and vice versa. Then, the optimal tradeoff is introduced, i.e., the conditions that the MIMO radar system should have, so that the diversity-multiplexing tradeoff is at its optimum point, are driven.