3D map reconstruction using a monocular camera for smart cities

Large-scale high-resolution three-dimensional (3D) maps play a vital role in the development of smart cities. In this work, a novel deep learning-based multi-view-stereo method is proposed for reconstructing the 3D maps in large-scale urban environments by exploiting a monocular camera. Compared with other existing works, the proposed method can perform 3D depth estimation more efficiently in terms of computational complexity and graphics processing unit memory usage. As a result, the proposed method can practically perform depth estimation for each pixel before generating 3D maps for even large-scale scenes. Extensive experiments on the well-known DTU dataset and real-life data collected on our campus confirm the good performance of the proposed method.

     

QRD-based precoded MIMO-OFDM systems with reduced feedback

QR decomposition (QRD)-based precoded MIMOOFDM systems with reduced feedback are proposed to convert the MIMO-OFDM channel into layered subchannels. QRD-M is further combined with either singular value (SVD) or geometric mean decomposition (GMD) of the time-domain channel impulse response matrix. As a result, the receiver in the proposed systems only needs to feed back information describing one precoding matrix for all carriers. Simulation results confirm the bit-error-rate (BER) and throughput performance superiority of the proposed systems compared to conventional SVD per-carrier precoding schemes.     

The continuous-time peak-to-average power ratio of OFDM signals using complex modulation schemes

Computing the continuous-time peak-to-averagepower ratio (PAPR) of OFDM signals is computationally challenging. The pioneering work by Tellambura applies only to OFDM signals using real-valued modulation schemes. In this paper, a practical technique for evaluating the continuous-time PAPR of OFDM signals using complex modulation is presented. Using the proposed scheme, it is confirmed that the four-time oversampled discrete-time PAPR is a good approximation of the continuous-time PAPR even for complex OFDM signals. Furthermore, the proposed scheme is employed to verify some existing analytical bounds on continuous PAPR in the literature.