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.

Nonlinear approximation based image recovery using adaptive sparse reconstructions and iterated denoising-part II: adaptive algorithms

Abstract: We combine the main ideas introduced in Part I with adaptive techniques to arrive at a powerful algorithm that estimates missing data in nonstationary signals. The proposed approach operates automatically based on a chosen linear transform that is expected to provide sparse decompositions over missing regions such that a portion of the transform coefficients over missing regions are zero or close to zero. Unlike prevalent algorithms, our method does not necessitate any complex preconditioning, segmentation, or edge detection steps, and it can be written as a progression of denoising operations. We show that constructing estimates based on nonlinear approximants is fundamentally a nonconvex problem and we propose a progressive algorithm that is designed to deal with this issue directly. The algorithm is applied to images through an extensive set of simulation examples, primarily on missing regions containing textures, edges, and other image features that are not readily handled by established estimation and recovery methods. We discuss the properties required of good transforms, and in conjunction, show the types of regions over which well-known transforms provide good predictors. We further discuss extensions of the algorithm where the utilized transforms are also chosen adaptively, where unpredictable signal components in the progressions are identified and not predicted, and where the prediction scenario is more general.

Low latency mobile initiated tunneling handoff

Abstract: The present invention provides a tunnel-based IP handoff process that can minimize the handoff latency associated with the standard Mobile IP registration. In the present invention, when neighboring nodes are detected, these detected nodes are identified as candidate nodes. Detection of just the existence of neighboring nodes should be possible even in situations where these neighboring nodes use different access technologies. For instance, pilot beacon signals may be taken as indication of the existence of candidate nodes although it may be impossible to compare them quantitatively if the beacon signals emanate from different access technologies. As soon as candidate nodes are identified, tunnels are established between the source node and the candidate nodes. The tunnels are used to forward data to the mobile node after a communication link between the mobile node and the source node goes down. As soon as the mobile node enters one of the neighboring networks and identifies a target node, the tunnels are torn down except the tunnel for the target node.

Energy Consumption Issues on Mobile Network Systems

Abstract: This paper describes energy consumption demographic data in operating real mobile networks. We examine published data from NTT DoCoMo, which is the largest mobile telecommunication operator in Japan and operating nationwide 3G networks, and identify the most power consuming part is of radio access networks including base tranciever stations. We also investigate power consumption of terminals, and find that the consumption ratio of terminal v.s. networks is about 1:150. Our daily energy consumption per a customer is 0.83 Wh/day for a terminal and 120 Wh/day for the mobile network. The terminal side energy consumption is negligible in view of total CO2 emission though, limitation of its battery performance raises another issue called "energy starvation of mobile devices." The demographic data leads our discussion to (1) radio-on-fiber access network architecture as green networks and (2) thin client models as the key to sustain the evolution toward the future.

Secure virtual architecture: a safe execution environment for commodity operating systems

Abstract: This paper describes an efficient and robust approach to provide a safe execution environment for an entire operating system, such as Linux, and all its applications. The approach, which we call Secure Virtual Architecture (SVA), defines a virtual, low-level, typed instruction set suitable for executing all code on a system, including kernel and application code. SVA code is translated for execution by a virtual machine transparently, offline or online. SVA aims to enforce fine-grained (object level) memory safety, control-flow integrity, type safety for a subset of objects, and sound analysis. A virtual machine implementing SVA achieves these goals by using a novel approach that exploits properties of existing memory pools in the kernel and by preserving the kernel's explicit control over memory, including custom allocators and explicit deallocation. Furthermore, the safety properties can be encoded compactly as extensions to the SVA type system, allowing the (complex) safety checking compiler to be outside the trusted computing base. SVA also defines a set of OS interface operations that abstract all privileged hardware instructions, allowing the virtual machine to monitor all privileged operations and control the physical resources on a given hardware platform. We have ported the Linux kernel to SVA, treating it as a new architecture, and made only minimal code changes (less than 300 lines of code) to the machine-independent parts of the kernel and device drivers. SVA is able to prevent 4 out of 5 memory safety exploits previously reported for the Linux 2.4.22 kernel for which exploit code is available, and would prevent the fifth one simply by compiling an additional kernel library.

User terminal and wireless communication method

Abstract: This user terminal is characterized by having: a transmission unit that uses an uplink control channel resource in a prescribed bandwidth part (BWP) and sends uplink control information; and a control unit that determines the correspondence between said uplink control channel resource and a prescribed index, on the basis of prescribed information, and specifies the uplink control channel resource. As a result of the present invention, reduction in communication throughput can be suppressed even when performing control on the basis of BWP.