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.

Apparatus and method for generating an error signal

Abstract: The invention relates to an apparatus for generating an error signal from an input signal, the error signal to be used for generating a transmit signal, the apparatus comprising: distorter for distorting the input signal to obtain a distorted signal, calculator for calculating a preliminary error signal representing a difference between the input signal and the distorted signal or representing the input signal, manipulator for manipulating the preliminary error signal to obtain the error signal, wherein the manipulator for manipulating is configured for varying a preliminary error signal value to obtain an error signal value which is non-equal to zero.

Application mobility service

Abstract: A method and system for preserving application session states among multiple terminals An application session state is captured from a first terminal The application session state is stored on a central storage device or repository server The application session state is then retrieved from the central storage device with a second terminal At least one application on the second terminal is then placed in the application session state using the information that is retrieved from the central storage device

Signature schemes using bilinear mappings

Abstract: Methods and systems are provided for generating and verifying signatures of digital messages communicated between signers and verifiers. Using bilinear mappings, such as Weil or Tate pairings, these methods and systems enable generation and verification of efficient multisignatures, identity-based ring signatures, hierarchical proxy signatures, and hierarchical online/offline signatures.

Using XCAP to certify realistic systems code: machine context management

Abstract: Formal, modular, and mechanized verification of realistic systems code is desirable but challenging. Verification of machine context management (a basis of multi-tasking) is one representative example. With context operations occurring hundreds to thousands of times per second on every computer, their correctness deserves careful examination. Given the small and stable code bases, it is a common misunderstanding that the context management code is suitable for informal scrutiny and testing. Unfortunately, after being extensively studied and used for decades, it still proves to be a common source of bugs and confusion. Yet its verification remains difficult due to the machine-level detail, irregular patterns of control flows, and rich application scenarios. This paper reports our experience applying XCAP--a recent theoretical verification framework--to certify a realistic x86 implementation of machine context management. XCAP supports expressive and modular logical specifications, but has only previously been applied on simple idealized machine and code. By applying the XCAP theory to an x86 machine model, building libraries of common proof tactics and lemmas, composing specifications for the context data structures and routines, and proving that the code behave accordingly, we achieved the first formal, modular, and mechanized verification of realistic x86 context management code. Our proofs are fully mechanized in the Coq proof assistant. Our certified library code runs on stock hardware and can be linked with other certified systems and application code. Our technique applies to other variants or extensions of context management (e.g., more complex context, different platforms), provides a solid basis for further verification of thread implementation and concurrent programs, and illustrates how to achieve formal, modular, and mechanized verification of realistic systems code.

Transmitter and transmission control method

Abstract: A transmitter has a peak reducing part carrying out peak reduction processing; an OFDM signal generating part generating an OFDM signal from an input information signal; a cyclic shifting part generating a signal obtained from cyclically shifting the OFDM signal; and an adding part adding the OFDM signal and the cyclically shifted signal together.