Signal model and detection performance for MIMO-OTH radar with multipath ionospheric propagation and non-point targets

Abstract

Taking into account the existence of multipath ionospheric propagation (MIP), this paper develops the received signal model for a non-point target for multiple-input multipleoutput skywave over-the-horizon (MIMO-OTH) radar for the first time. The model describes the ionospheric state, the number of propagation paths between a radar antenna and the target center, as well as the statistics of the reflection coefficients. It is shown that varying system parameters, such as antenna positions and signal frequencies, can result in causing the model to change from a case with highly correlated reflection coefficients to a case with virtually uncorrelated reflection coefficients. The proposed model is used to solve a target detection problem. It is shown that it is possible to exploit the MIP to improve the detection performance of the MIMO-OTH radar.Index Terms-Detection, multipath, non-point target.1. INTRODUCTION Skywave over-the-horizon (OTH) radar employs ionospheric reflection of signals to detect targets beyond visual range. The performance of the OTH radar system relies heavily on the state of the ionosphere. The commonly used models for describing the ionospheric state usually divide the ionosphere into several layers. These models include the international reference ionosphere (IRI) model [1], the Chapman ionosphere model [2], and the multi-quasi-parabolic (MQP) ionospheric model [3], etc. In OTH radar, transmit signals can travel through different ionospheric layers to reach the target depending on their frequencies, and the signal which bounces off the target can also travel through different ionospheric layers before reaching the receivers, leading to multiple propagation paths, a phenomenon called multipath ionospheric propagation (MIP). In traditional OTH radar systems, approaches have been proposed to attempt to eliminate MIP, for example, by selectively choosing the operational frequency, employing a transmit/receive array with higher angular reso-

Time‐slotted interactive multiple‐input multiple‐output radar for phase synchronisation at target with low overhead

“…Similarly, is the distance between the target and the n th antenna of Array 2 in the k th timeslot, denoted as Here we assume that the amplitude response of each path, is modelled as a complex Gaussian random variable with zero mean and variance [21], where the level of variance is dependent on the velocity of the moving target, the characteristic of target scattering as well as the communication circumstance. For a stationary target scenario, the variance can be simplified as unit for each of the signal path, just like in [22].…”