NTT DoCoMo

About: NTT DoCoMo is a based out in . It is known for research contribution in the topics: Base station & Mobile station. The organization has 4032 authors who have published 8655 publications receiving 160533 citations.

Cost-Based Analysis of Hierarchical DHT Design

Abstract: Flat DHT architectures have been the main focus of the research on DHT design so far. However, there have been also a number of works proposing hierarchical DHT organizations and pointing their advantages. They mostly rely on the intuitive understanding that hierarchy is desirable in any complex system. In this paper we formalize this intuition within a general cost-based framework. We provide a cost model of a specific hierarchical DHT organization composed of superpeers and leafnodes, and show that the costs of running the network are not necessarily minimized for flat DHT organization, providing thus a formal motivation for hierarchical DHTs. We further hint on what distributed algorithms can be applied in practice to reach optimal operating point of the network.

A method and apparatus for constructing security policies for web content instrumentation against browser-based attacks

Abstract: A method and apparatus is disclosed herein for constructing security policies for content instrumentation against attacks. In one embodiment, the method comprises constructing one or more security policies for web content using at least one rewriting template, at least one edit automata policy, or at least one policy template; and rewriting a script program in a document to cause behavior resulting from execution of the script to conform to the one or more policies.

Energy Source Aware Target Cell Selection and Coverage Optimization for Power Saving in Cellular Networks

Abstract: The spread of mobile connectivity is generating major social and economic benefits around the world, while along with the rapid growth of new telecommunication technologies like mobile broadband communication and M2M (Machine-to-Machine) networks, larger number of various base stations will be employed into the network, which will greatly increase the power expense and CO2 emission. In order to degrade the system power expense, variety of researches on new energy and novel transmission technology are put in agenda. In this paper, instead of reducing the absolute power expense, the research focuses on guiding more power consumption into green source energy, which implying that the UEs (User Equipment), especially the cell edge UEs, will have preferential access to the BSs (Base Station) with natural energy supply. To realize the tendentious connection, two detailed approaches are proposed, the HO (Hand Over) parameter tuning for target cell selection and power control for coverage optimization. The system evaluation shows that, by proper setting of parameters in HO and power control, both of the two approaches can achieve good balance between energy saving effect and system throughput impact.

Motion vector prediction in video coding

Abstract: A method and apparatus is disclosed herein for motion vector prediction and coding. In one embodiment, the method comprises: deriving N motion vector predictors for a first block that has N motion vectors corresponding to N lists of reference frames and a current frame, including constructing one of the N motion vector predictors when a second block that neighbors the first block and is used for prediction has at least one invalid motion vector, where N is an integer greater than 1; generating N differential motion vectors based on the N motion vectors and N motion vector predictors; and encoding the N differential motion vectors.

Cellular vs. Network MIMO: A comparison including the channel state information overhead

Abstract: Cooperative base-station (BS) signaling using MU-MIMO (Network MIMO) has received a great deal of attention given its ability to reduce inter-cell interference (ICI) and improve the system spectral efficiency. Indeed for a given number of antennas per BS, cooperative systems can have significant benefits over conventional cellular architectures. However cooperative signaling requires and uses more channel state information (CSI). This increases CSI signaling overhead, and can have a non-negligible effect on the system throughput. In fact once systems are compared while taking into account CSI overhead, the question of what system architecture is best becomes interesting and non-trivial. We provide one such alternative look at cooperative architectures. We show, despite prevailing views, that cellular architectures, using coordinated colocated antennas, can be quite attractive compared to Network MIMO.