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.

Input key and input apparatus

Abstract: An input apparatus, which has at least one input key 10 assigned a plurality of information items to be inputted, is provided with a push detector 36 for detecting a push on the input key 10; a direction detector 38 for detecting a strain occurring in the input key 10 when the push is detected, and for thereby detecting a direction of a force exerted on the input key 10; and a symbol determiner 40 for determining an input information item, based on the detected direction.

Mobility Management Schemes at Radio Network Layer for LTE Femtocells

Abstract: Femtocell, a small cellular base station in home and small business environment, is an attractive solution for operators to improve indoor coverage and network capacity in 3G networks. However, there are technical problems due to its mass deployment. The paper presents a femtocell architecture for LTE and investigates different handover scenarios. Two mobility management schemes at radio network layer (RNL) are proposed and their signaling cost, complexity, standard impact and application scenarios are also discussed.

UWB Direct Chaotic Communication Technology for Low-Rate WPAN Applications

Abstract: The goal of this paper is to describe the design of an ultrawideband (UWB) system that is optimized for low-complexity, low-power, low-cost, and low-rate wireless personal area network applications. To this aim, we propose a system based on novel direct chaotic communication (DCC) technology, in which a 2-GHz-wide chaotic signal is directly generated into the lower band of the UWB spectrum. Based on this system, two simple modulation schemes, namely, chaotic on-off keying and differential chaos-shift keying, are studied, and the performance of both noncoherent and differential-coherent transceiver architectures is evaluated. Various system design parameters and tradeoffs are discussed throughout the paper, including frequency band plans, data throughput, and system scalability. In particular, the frequency-division multiplexing technique is proposed as a low-cost alternative to achieving simultaneous operating piconets for short-distance applications. The average power consumption for various operating data rates and the technical feasibility of implementing the DCC system as a low-cost integrated circuit are also addressed. Finally, Monte Carlo simulations are performed based on the IEEE 802.15.4a standard channel models to evaluate the performance of the two modulation schemes. In general, both schemes experience little degradation under multipath environments due to the self-inherent wideband characteristic of the chaotic signal.

Key Recovery and Message Attacks on NTRU-Composite

Abstract: NTRU is a fast public key cryptosystem presented in 1996 by Hoffstein, Pipher and Silverman of Brown University. It operates in the ring of polynomials Z[X]/(XN - 1), where the domain parameter N largely determines the security of the system. Although N is typically chosen to be prime, Silverman proposes taking N to be a power of two to enable the use of Fast Fourier Transforms. We break this scheme for the specified parameters by reducing lattices of manageably small dimension to recover partial information about the private key. We then use this partial information to recover partial information about the message or to recover the private key in its entirety.

Multiband mobile communication system and transmitter used therein

Abstract: A transmitter used in the multiband environment includes a frequency allocation unit (106) configured to select and allocate a frequency band that satisfies a user QoS from among multiple separate frequency bands currently available for the user, a parameter determination unit (111) configured to determine a transmission parameter required for signal transmission based on the allocated frequency band, and a multi-user scheduling control unit (110) configured to determine a transmission schedule for multiple users taking into account the frequency bands allocated to the multiple users.