This paper investigates the use of ground-penetrating radar (GPR) technology for detecting shallow buried objects, utilizing an air-coupled stepped frequency continuous wave (SFCW) radar system that operates within a 2 GHz bandwidth starting at 500 MHz. Different GPR data acquisition methods for air-coupled systems are compared, specifically down-looking, side-looking, and circular acquisition strategies, employing the back projection algorithm to provide focusing of the acquired GPR data. Experimental results showed that the GPR can penetrate up to 0.6 m below the surface in a down-looking mode. The developed radar and the back projection focusing algorithm were used to acquire data in the side-looking and circular mode, providing focused images with a resolution of 0.1 m and detecting subsurface objects up to 0.3 m below the surface. The proposed approach transforms B-scans of the GPR-based data into 2D images. The provided approach has significant potential for advancing shallow object detection capabilities by transforming hyperbola-based features into point-like features.

This paper investigates the ergodic rates of three cooperative strategies for the fast Rayleigh fading relay channel, namely, decode-and forward (DF), compress-and-forward (CF) and amplify-and-forward (AF). The transmitter-relay, relay-receiver and transmitter-receiver links experience independent fast Rayleigh fading. Our analysis considers both full duplex and half-duplex modes of operation of the relay channel, assuming that perfect transmit channel distribution information (CDI) is available at the transmitter and the relay. The ergodic rates are compared under different channel conditions to the corresponding upper capacity bounds of the relay channel and to the rate of direct transmission in order to investigate when it is beneficial to use a certain cooperative strategy. Cooperative transmission makes the ergodic rates approach or even become identical to the upper capacity bounds if some conditions are satisfied. The results show that DF and CF outperform AF as they are more complex strategies, while AF itself achieves higher rates than direct transmission in most channel scenarios, thus trading performance for implementation simplicity. ACM Computing Classification System (1998): E.4, C.2.1.