Joint Range and Velocity Estimation With Intrapulse and Intersubcarrier Doppler Effects for OFDM-Based RadCom Systems

In order for an orthogonal frequency division multiplexing (OFDM)-based radar and communication (RadCom) system to perform well, accurate range and velocity estimation needs to be realized. To achieve this goal, the intrapulse and intersubcarrier Doppler effects that are both typically ignored in conventional methods must be considered and properly utilized. In this article, we first conceive of a complete receiving model considering the intrapulse and intersubcarrier Doppler effects. Then, an alternating projection - maximum likelihood (AP-ML) method is developed based on this complete model. Considering the heavy computational burden of the AP-ML method, the use of the expectation maximization (EM) algorithm is introduced to reduce the computational complexity. Simultaneously, the computational cost of the EM algorithm can be further reduced by using the reduced-rank technique. Consequently, better estimation results can be obtained with this reduced-rank EM algorithm when there are no approximation errors. Moreover, an analytical expression of the Cramer-Rao bound (CRB) is provided for the complete receiving model. The mutual impacts between the radar and communication functions are analyzed in detail. Finally, excellent experimental results illustrate the superiority of our proposed methods.