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.

A method and apparatus for reliable multicasting in wireless relay networks

Abstract: A method and apparatus is disclosed herein for performing multi casting. In one embodiment, the method comprises receiving routing, association, relaying, and/or topology information associated with a plurality of nodes in a multi-hop wireless network, the plurality of nodes communicably coupled in a tree or mesh arrangement via a plurality of broadcast channels; and determining a subset of the plurality of nodes over each broadcast channel on the multi-hop wireless network that is responsible for sending acknowledgment information, in response to receipt or lack of receipt of transmissions, back to senders of transmissions.

Efficient dissemination of personalized information using content-based multicast

Abstract: There has been a surge of interest in the delivery of personalized information to users (eg, personalized stocks or travel information), particularly as mobile users with limited terminal device capabilities increasingly desire updated and targeted information in real time When the number of information recipients is large and there is sufficient commonality in their interests, as is often the case, IP multicast is an efficient way of delivering the information However, IP multicast services do not consider the structure and semantics of the information in the multicast process We propose the use of Content-Based Multicast (CBM) where extra content filtering is performed at the interior nodes of the IP multicast tree; this will reduce network bandwidth usage and delivery delay, as well as the computation required at the sources and sinks We evaluate the situations in which CBM is advantageous The benefits of CBM depend critically upon how well filters are placed at interior nodes of the IP multicast tree and the costs depend upon those introduced by filters themselves Further, we consider the benefits of allowing the filters to be mobile so as to respond to user mobility or changes in user interests and the corresponding costs of filter mobility The criterion that we consider is the total network bandwidth utilization For this criterion, we develop an optimal filter placement algorithm, as well as a heuristic that executes faster than the optimal algorithm We evaluate the algorithms by means of simulation experiments Our results indicate that filters can be effective in substantially reducing bandwidth We also find filter mobility is worthwhile if there is marked large-scale user mobility We conclude with suggestions for further work

User terminal, radio base station, radio communication system and radio communication method

Abstract: The present invention is designed to enable 1-CC transmission when carrier aggregation is carried out by aggregating a first component carrier, which is used in a macro cell, and a second component carrier, which is used in a small cell. A user terminal according to the present invention receives duration configuration information, which indicates a first duration to communicate with a macro base station by using the first component carrier, and a second duration to communicate with a small base station by using the second component carrier, configures the first duration and the second duration based on the duration configuration information, transmits uplink signals for the macro base station by using the first component carrier in the first duration, and transmits uplink signals for the small base station by using the second component carrier in the second duration.

Mobile communication system, radio base station and mobile station

Abstract: In a mobile communication system according to the present invention, a data transmitting-side apparatus is configured to retransmit a transmission data block according to a transmission acknowledgement signal transmitted from a data receiving-side apparatus. The data receiving-side apparatus includes: a maximum number-of-retransmissions manager unit configured to manage the maximum number of retransmissions of the transmission data block; and a transmission acknowledgement signal transmitter unit configured not to transmit the transmission acknowledgement signal, when the number of retransmissions of the transmission data block reaches the maximum number of retransmissions.

Synchronous detector and synchronizing method for digital communication receiver

Abstract: A synchronous detecting method in which the transfer function of a propagation path is estimated by regarding the information symbols adjacent to pilot signals as known symbols and using the information symbols as pseudo-pilot signals. The method includes a step of estimating the transfer function by using the pilot signals, a step of performing interpolation synchronous detection of part of the information symbols by using the estimated transfer function, a step of storing the result of the interpolation synchronous detection as pseudo-pilot signals, a step of reestimating the transfer function related to information symbols corresponding to the pseudo-pilot signals from the pseudo-pilot signals and the received signals corresponding to the pseudo-pilot signal, regarding the pseudo-pilots as known correct signals, and a step of performing interpolation synchronous detection of each information symbol by using the reestimated transfer function. Thus, the detection characteristic can be improved by estimating the transfer function with high accuracy even when the number of symbols per pilot signal is small.