As a newly proposed video coding standard, Versatile Video Coding (VVC) has adopted some revolutionary techniques compared to High Efficiency Video Coding (HEVC). The multiple-mode affine motion compensation (MM-AMC) adopted by VVC saves approximately 15%-25% Bjøntegaard Delta Bitrate (BD-BR), with an inevitable increase of encoding time. This paper gives an overview of both the 4-parameter affine motion model and the 6-parameter affine motion model, analyzes their performances, and proposes improved algorithms according to the symmetry of iterative gradient descent for fast affine motion estimation. Finally, the proposed algorithms and symmetric MM-AMC flame of VTM-7.0 are compared. The results show that the proposed algorithms save 6.65% total encoding time on average, which saves approximately 30% encoding time of affine motion compensation.

In order to suppress effectively the effects of RSSI error to wireless sensor networks node localization's precision in pervasive computing environment, individual diversity difference coefficient, distance difference coefficient and distance difference localization equation is defined based on the analysis of the models of maximum likelihood estimation and RSSI. The closest beaconing node to object node as reference node corrects measure distance based on RSSI by difference method. A distance difference localization algorithm is put forward through combining difference correction method and maximum likelihood estimation method. This localization algorithm needn't additional hardware spending, easy to be realized and its localization error is less than 2.5 m, therefore it is fit for localization of WSN node whose operation ability and power supply are restricted.

A data organization and access mechanism model of the spatial information grid is developed for effectively solving the spatial information share in pervasive computing environment. An architecture of campus location-based services based on grid geographical information system (CLGG) is proposed for services sharing, which composed of location tier, data tier, service tier and application tier. In the end, a prototype system is designed realizing district navigation and real time location and hot district information release, etc. These functions of the prototype validate the feasibility and validity of the mechanism model and the architecture.