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.

Method for time frequency spreading in a femtocell network for interference reduction

Abstract: A femtocell network uses idle resource blocks of a data frame to reduce interference by spreading the resource blocks of the users over the available spectrum Spreading may be achieved by repeating the transmission using a number of the resource block groups As a result, (a) more robustness is obtained against interference; (b) transmission power levels may be decreased because of the spreading, resulting in reducing interference between nearby femtocells and between a macrocell and a femtocell Other methods of spreading such a frequency or time slot hopping may also be used

QuasiModo: Efficient Certificate Validation and Revocation

Abstract: We present two new schemes for efficient certificate revocation. Our first scheme is a direct improvement on a well-known tree-based variant of the NOVOMODO system of Micali [11]. Our second scheme is a direct improvement on a tree-based variant of a multi-certificate revocation system by Aiello, Lodha, and Ostrovsky [1]. At the core of our schemes is a novel construct termed a QuasiModo tree, which is like a Merkle tree but contains a length-2 chain at the leaves and also directly utilizes interior nodes. This concept is of independent interest, and we believe such trees will have numerous other applications. The idea, while simple, immediately provides a strict improvement in the relevant time and communication complexities over previously published schemes.

Base station apparatus, user equipment, and method used in mobile communication system

Abstract: A base station apparatus for a mobile communication system is disclosed that includes a unit to receive an uplink reference signal transmitted from user equipment, a unit to provide transmission power control data indicating whether a transmission power value of the uplink reference signal to be transmitted later is to be changed, a unit to derive a first offset power value so that the uplink control signal is transmitted at a power value determined by adding the first offset power value to the transmission power value of the uplink reference signal, a unit to derive a second offset power value so that the uplink control signal is transmitted at a power value determined by adding the second offset power value to the transmission power value of the uplink reference signal, and a unit to report the data and values to the user equipment.

Call acceptance control method for cdma mobile radio communication system and mobile station device

Abstract: A call acceptance control method for a CDMA mobile radio communication system and a mobile station device which enable prevention of deterioration in radio communication quality of a communicating mobile station even under a dense traffic, sufficient suppression of the possibility of deteriorating the communication quality of a mobile station communicating with a peripheral base station, and improvement in efficiency without increasing a control signal traffic. A radio base station device measures the quantity of up-link interference and informs a mobile station of this quantity. The mobile station obtains the quantity of up-link interference informed of by the base station, and calculates a required receiving level at the base station anticipated in the case where the mobile station is accepted by the connected base station, on the basis of the obtained quantity of up-link interference. If it is judged that predetermined communication quality cannot be realized on the basis of the calculated required receiving level and the quantity of up-link interference, the call of the mobile station is determined to be unacceptable.

Mobile terminal apparatus and diagnosis method for mobile terminal apparatus

Abstract: To provide a mobile terminal apparatus with the lower communication cost in sending a log at the occurrence of a malfunction, abnormality or fault in the mobile terminal apparatus to a network. A diagnostic process for the malfunction is performed in accordance with a diagnostic policy acquired from the outside. An error code corresponding to the diagnostic result is generated. The generated error code is outputted. With an automatic fault diagnostic function of automatically analyzing the fault in the mobile terminal apparatus without directly sending the log collected in the mobile terminal apparatus to an analytic server, the communication cost can be reduced.