CDR Based Trajectories: Tentative for Filtering Ping-pong Handover

Call Detail Records (CDRs) coupled with the coverage area locations provide the operator with an incredible amount of information on its customers' whereabouts and movement. Due to the non-static and overlapping nature of the antenna coverage area there commonly exist situations where cellphones geographically close to each other can be connected to different antennas due to handover rule - the operator hands over a certain cellphone to another antenna to spread the load between antennas. Hence, this aspect introduces a ping-pong handover phenomena in the trajectories extracted from the CDR data which can be misleading in understanding the mobility pattern. To reconstruct accurate trajectories it is a must to reduce the number of those handovers appearing in the dataset. This letter presents a novel approach for filtering ping-pong handovers from CDR based trajectories. Primarily, the approach is based on anchors model utilizing different features and parameters extracted from the coverage areas and reconstructed trajectories mined from the CDR data. Using this methodology we can significantly reduce the ping-pong handover noise in the trajectories, which gives a more accurate reconstruction of the customers' movement pattern.

Evaluation of the Robustness of Visual SLAM Methods in Different Environments

Determining the position and orientation of a sensor vis-a-vis its surrounding, while simultaneously mapping the environment around that sensor or simultaneous localization and mapping is quickly becoming an important advancement in embedded vision with a large number of different possible applications. This paper presents a comprehensive comparison of the latest open-source SLAM algorithms with the main focus being their performance in different environmental surroundings. The chosen algorithms are evaluated on common publicly available datasets and the results reasoned with respect to the datasets' environment. This is the first stage of our main target of testing the methods in off-road scenarios.