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.

Packet transmission method and communication system

Abstract: The object is to prevent occurrence of packet loss in Cellular IP and a drop of TCP throughput due to duplication of packets. On the occasion of relaying a packet from correspondent, a relay router multicasts a router advertisement to access routers forming respective cells into which a target mobile terminal might move. The mobile terminal receives the router advertisements from the neighbor access routers, calculates a difference between reception times of the packets from the respective access routers, and specifies a relay router to perform multicasting. Then the mobile terminal transmits delay information of a delay to be added to each path in multicasting by the relay router, to the relay router thus specified. The relay router adds the delay to each path in multicasting on the basis of the delay information.

Real-World Reasoning with OWL

Abstract: This work is motivated by experiences in the course of developing an ontology-based application within a real-world setting. We found out that current benchmarks are not well suited to provide helpful hints for users who seek for an appropriate reasoning system able to deal with expressive terminological descriptions, large volumes of assertional data, and frequent updates in a sound and complete way. This paper tries to provide some insights into currently available reasoning approaches and aims at identifying requirements to make future benchmarks more useful for application developers.

Method and apparatus for transmission power control of a mobile station during soft handoff in a CDMA system

Abstract: A transmission power control method in CDMA, which is capable of increasing the capacity in terms of the number of subscribes by reducing transmission power by achieving highly accurate transmission power control during a soft handoff. A mobile station (PS1) determines its transmission power during the soft handoff by comparing a transmission power control bit from the old base station (BS1) with that from a new base station (BS2), and by selecting the transmission power control bit that indicates lower transmission power of the mobile station (PS1). In addition, the mobile station (PS1) determines the transmission power control bit for the base stations (BS1,BS2) by comparing the received SIR from the old base station (BS1) with that from the new base station (BS2), and by selecting the greater received SIR. This make it possible to reduce the transmission power, and increase the capacity in terms of the number of subscribers.

Ofdma-based co-channel femtocell

Abstract: A femtocell increases efficiency and coverage of a macrocellular network operating in a co-channel manner within the macrocell spectrum by selecting subcarriers for its mobile station using both the subcarrier allocation map received from the macrocell and a spectrum sensing operation. Interference is avoided by selecting only subcarriers not allocated by the macrocell and subcarriers allocated to users not nearby to the femtocell. Interference is eliminated from the received signals using co-channel interference avoidance techniques. Selection of subcarriers for femtocell use may take into consideration inter-carrier interference detected.

Password authenticated key exchange using hidden smooth subgroups

Abstract: Existing techniques for designing efficient password authenticated key exchange (PAKE) protocols all can be viewed as variations of a small number of fundamental paradigms, and all are based on either the Diffie-Hellman or RSA assumptions. In this paper we propose a new technique for the design of PAKE protocols that does not fall into any of those paradigms, and which is based on a different assumption. In our technique, the server uses the password to construct a multiplicative group with a (hidden) smooth order subgroup, where the group order depends on the password. The client uses its knowledge of the password to generate a root extraction problem instance in the server's group and a discrete logarithm problem instance in the (smooth order) subgroup. If the server constructed its group correctly based on the password, the server can use its knowledge of the group order to solve the root extraction problem, and can solve the discrete logarithm problem by leveraging the smoothness of the hidden subgroup.The resulting scheme is provably secure (in the random oracle model) under the "decision subgroup assumption." The scheme can be efficiently instantiated using composite modulus groups, in which case the client and server each perform the equivalent of a small number of modular exponentiations, and the security reduces to a simple variant of the "Φ-hiding" assumption. We provide preliminary implementation results of this instantiation.