Focusing on the issue that the HBase storage without spatio-temporal index degrades the traffic data query performance, some HBase spatio-temporal indexes based on row keys were proposed for massive traffic data. Firstly, the dimensionality reduction method based on Geohash was used to convert two-dimensional spatial position data into a one-dimensional code. Then the code was combined with the temporal dimension. Secondly, four index models were put forward based on combination order, and the structures of the models and their adaption conditions for traffic data query were discussed. Finally, the algorithm of index creation as well as traffic data query algorithm was proposed. Experimental results show that the proposed HBase spatio-temporal index structure can effectively enhance the traffic data query performance. In addition, the query performance of four different spatio-temporal index structures in different data size, different query radius and different query time range were compared, which verified the different adaption scenes of different index structures in traffic data query.
In Video-On-Demand (VOD) applications, it is desired that the encrypted multimedia data are still partially perceptible after encryption in order to stimulate the purchase of the high-quality versions of the multimedia products. This perceptual encryption requires specific algorithms for encrypting the video data. Duo to lack of H.264 video perceptual encryption algorithms for mobile communication application, a video encryption algorithm based on ZU Chongzhi's (ZUC) algorithm and Compressive Sensing (CS) was proposed. First of all, ZUC algorithm was utilized to construct a random measurement matrix. Then the quantified Discrete Cosine Transformation (DCT) coefficients were measured by measurement matrix, and the measured values were regarded as new quantified DCT coefficients to encode, which realized the encryption by using the difference between original and new coefficients. Finally, the characteristics of a good perception encryption algorithm were defined. The experimental results show that the proposed algorithm has little effect on video compression bit rate with low time complexity, and it is also sensitive to key change with good perceptual security.