Abstract: Some implementations relate to methods, systems, and computer readable media for partitioning large-scale virtual environments across multiple servers. Data representing a virtual environment is received, including multiple virtual regions with associated computational and memory loads. Communication metrics between adjacent virtual regions are determined. Each virtual region is assigned to a respective server based on balancing computational and memory loads and reducing communication metrics between virtual regions assigned to different servers. The assignment of virtual regions is refined iteratively, such that virtual regions with dense interaction are grouped together on a common server to reduce inter-server communication. State data for virtual regions located at boundaries between server assignments is replicated to neighboring servers.

Abstract: Some implementations relate to methods, systems, and computer readable media to manage object states in a distributed multiuser environment, such as a multiplayer game environment. A client device receives an authoritative update from a designated authority node specifying a state of at least one object for a given frame. The client performs a rollback check to determine whether the locally predicted state differs from the authoritative update. If a discrepancy exists, the client rolls back the local state to a time corresponding to the authoritative update and applies the update to obtain an updated object state. A subsequent object state is predicted based on the updated object state and used to update a game state maintained at the client. Visual discrepancies between a last shown position and the updated game state are reconciled before rendering the object for the next frame.

Abstract: According to one aspect of the present disclosure, a computer-implemented method of a virtual-experience coordinator is provided. The computer-implemented method includes determining, by a processor, a plurality of regions associated with a virtual experience. Each of the plurality of regions is associated with a different set of virtual-experience models and virtual-experience scripts. The computer-implemented method includes assigning, by the processor, each of the plurality of regions to a respective virtual-experience server of a plurality of virtual-experience servers. The computer-implemented method includes causing, by the processor, each of the plurality of virtual-experience servers to simulate its assigned region.

Abstract: A computer-implemented method includes obtaining, by a processor, an initial version of a set of tables associated with a region of a virtual experience. Each row contains information associated with a virtual object located in a corresponding portion of the region. The method includes simulating, by the processor, the initial frame of the region of the virtual experience based at least in part on the initial version of the set of tables. The method includes generating, by the processor, an updated version of the set of tables associated with the region based on one or more first changes to a first virtual object in the region of the virtual experience. The method includes simulating, by the processor, the subsequent frame of the region of the virtual experience based at least in part on the updated version of the set of tables.

Abstract: Some implementations relate to methods, systems, and computer-readable media to render a graphical simulation of a fluid in a physical region in a virtual experience. In some implementations, the method includes dividing the physical region into cells, providing an initial state for each cell, calculating a fluid state for each cell at each of a plurality of consecutive time steps by determining pre-existing information for at least one cell to use when updating the fluid state of that cell, and recalculating the fluid state for each cell based on a previous fluid state of the cell and any external force affecting the cell, via Navier-Stokes equations. The recalculating uses the pre-existing information for each cell. For example, the recalculating achieves a low computational cost by using the pre-existing information to avoid operations otherwise performed during the recalculating. Once the calculation is complete, the graphical simulation is rendered.

Abstract: A mechanism called time-deterministic replay (TOR) that can reproduce the execution of a program, including its precise timing. Without TOR, reproducing the timing of an execution is difficult because there are many sources of timing variability. TOR uses a combination of techniques to either mitigate or eliminate most of these sources of variability. Using a prototype implementation of TOR in a Java Virtual Machine, we show it is possible to reproduce the timing to within 1.85% of the original execution. A study of one of the applications of TOR is described: the detection of a covert timing channel. Timing channels can be used to exfiltrate information from a compromised machine by subtly varying timing of the machine's outputs, TOR can detect this variation. Unlike prior solutions, which generally look for a specific type of timing channel, our approach can detect a wide variety of channels with high accuracy.

Abstract: A mechanism called time-deterministic replay (TOR) that can reproduce the execution of a program, including its precise timing. Without TOR, reproducing the timing of an execution is difficult because there are many sources of timing variability. TOR uses a combination of techniques to either mitigate or eliminate most of these sources of variability. Using a prototype implementation of TOR in a Java Virtual Machine, we show it is possible to reproduce the timing to within 1.85% of the original execution. A study of one of the applications of TOR is described: the detection of a covert timing channel. Timing channels can be used to exfiltrate information from a compromised machine by subtly varying timing of the machine's outputs, TOR can detect this variation. Unlike prior solutions, which generally look for a specific type of timing channel, our approach can detect a wide variety of channels with high accuracy.

Abstract: A system for locating a wireless device involves the use of the measured signal strength of various base stations in the building or outdoor area under analysis. A topological map of the building or outdoor area under analysis is created. The map is divided into cells, and signal intensities are collected in each cell. For each cell, the signal from a particular base station is fit to a statistical distribution, such as a Gaussian distribution, and the parameters of the statistical distribution are estimated. After a device obtains a set of signal strength measurements, a probabilistic technique is employed to estimate the probability of the existence of the measurements in each of the cells of the building or area under analysis. The estimated location is the cell with the highest probability. A mobile user is tracked with the use of a Markov chain and the system can be calibrated to account for equipment and environmental variations.

Abstract: According to the present invention a method, device and a computer program product is provided for packet-level routing. The method, the device and the respective computer program product may be used in a computer system being connected to a communications network. The computer system includes a kernel providing a first interface for sending and retrieving data packets to the data link layer, a second interface for sending and retrieving data packets to the network layer, and filtering means for controlling the transportation of data packets to and from the network layer.