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.

System Level Performance of Downlink MU-MIMO Transmission for 3GPP LTE-Advanced

Abstract: We investigate enhanced downlink multiuser multiple input multiple output (MU-MIMO) transmission schemes for 3GPP LTE-Advanced based on system level simulations. As compared to Rel. 8 LTE single user MIMO (SU-MIMO), MU-MIMO has the potential to better exploit the spatial dimension of MIMO channels in some scenarios. Although Rel. 8 LTE defines a simple MU-MIMO mode, more advanced MU-MIMO techniques are currently discussed towards Rel. 10 LTE-Advanced to further improve the spectral efficiency. In this paper, we focus on zero-forcing (ZF) MU-MIMO precoding with an explicit channel quantization mechanism called channel vector quantization (CVQ). Moreover, we consider two different criteria of CVQ at the receiver: either minimizing Euclidean distance or maximizing the signal to interference plus noise power ratio (SINR). A number of system level simulations reveal significant potential gains of ZF MU-MIMO as compared to those of Rel. 8 LTE SU/MU-MIMO in terms of both cell throughput and cell-edge user throughput when the spatial correlations at the base station (eNB) are relatively high. The potential gain of ZF MU-MIMO is shown to be further improved when the CVQ is based on the SINR maximization criterion instead of Euclidean distance minimization.

Character input device

Abstract: A character input device not completely occupying a screen, good in visibility, and enabling input of characters while reducing to a minimum the movement of the fingers and line of sight, which, in the case of input of for example the hiragana 50-character phonetic syllabary of the Japanese language, displays an initial block of the major group lead characters a ( ), ka ( ), sa ( ), ta ( ), na ( ) on a first row of a character input region on a display screen and the block of the remaining major group lead characters ha ( ), ma ( ), ya ( ), ra ( ), wa ( ) on the second row, allows movement of a focus position or character position by “left” and “right” keys (a ( )→ka ( )→sa ( )→ . . . ), switches the character focused to the block of ha ( ), ma ( ), ya ( ), ra ( ), wa ( ) after the focus position reaches na ( ), allows switching between displayed characters by for example using the “down” key to move to the next character (for example, a ( )→i ( )→u ( )→ . . . ) and using the “up” key to move to the furthest character in the group (for example, a ( )→o (

Mobile communication method, mobile station, and wireless base station

Abstract: The mobile communication method has a step wherein a mobile station (UE) generates first verification information using a first key, a first parameter, and an algorithm for ‘Integrity Protection,’ a step wherein the mobile station (UE) generates second verification information by excising a specific bit in the first verification information, and a step wherein, when a wireless link obstruction is detected in an RRC connection, the mobile station (UE) performs cell selection processing and transmits an RRC‑PDU for an RRC reconnection request, wherein the second verification information is set, over a shared control channel to the wireless base state that manages the selected cell.

Dynamic service adaptation

Abstract: Change can be observed in our environment and in the technology we build. While changes in the environment happen continuously and implicitly, our technology has to be kept in sync with the changing world around it. Although for some of the changes we can prepare, for most of them we cannot. This is especially true for next generation mobile communication systems that are expected to support the creation of a ubiquitous society where virtually everything is connected and made available within an organic information network. Resources frequently join or leave the network, new types of media or new combinations of existing ones are used to interact and cooperate, and services are tailored to preferences and needs of individual customers to better meet their needs. We outline our research in the area of dynamic service adaptation to provide concepts and technologies allowing for such environments.

Mobile device, content distribution system, and content distribution method

Abstract: The present invention provides a mobile device that is able to receive content of a server even before a predetermined time interval elapses. The mobile device comprises a first transmission portion, which transmits a content transmission request to a first server, a second transmission portion, which transmits a content transmission request to a second server, a transmission control portion, which outputs transmission instruction information ordering the transmission of a content transmission request to the first transmission portion and second transmission portion, and a notice reception portion, which receives an urgent notice that is transmitted from the first server. The transmission control portion outputs transmission instruction information to the first transmission portion at a predetermined first time interval or when the notice reception portion receives the urgent notice, and outputs transmission instruction information to the second transmission portion at a second predetermined time interval.