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.

Improved Blind Interference Alignment in a Cellular Environment Using Power Allocation and Cell-Based Clusters

Abstract: Fundamentally, benefits of Multiple Input Multiple Output (MIMO) in wireless systems rest on increasing the number of Degrees of Freedom (DoFs) that can be exploited for transmission. DoFs can be used to increase spectral efficiency and/or provide increased diversity. However, exploiting DoFs in MIMO often requires knowledge of Channel State Information (CSI) at the transmitter and/or receiver. Obtaining CSI creates overheads due to the required use of wireless resources for CSI-estimation pilots and/or CSI feedback. This can create a fundamental "dimensionality bottleneck" that limits the growth in spectral efficiency for some conventional MIMO systems. Recently a new class of techniques known as "Blind Interference Alignment" (BIA) has demonstrated the possibility to grow DoFs without many of the CSI overheads of conventional systems. BIA therefore has the potential to relieve the "dimensionality bottleneck". However, BIA can have limited applicability to many users in a cellular environment given that it requires a high Signal to Noise Ratio (SNR) to operate efficiently. By examining BIA, we present a method to reduce the SNR requirements and improve the application of BIA through power allocation and cluster-based transmission. We show that BIA can be applied successfully in cellular without the need for joint processing between base-stations, and can improve performance over conventional MIMO for even cell-edge users in some scenarios.

Quadrature hybrid circuit

Abstract: In a quadrature hybrid circuit which has first and second two-port circuits 11 and 12 inserted between I/O ports P 1 and P 2 and between I/O ports P 4 and P 3 , respectively, and third and fourth two-port circuits inserted between I/O ports P 1 and P 4 and between I/O ports P 2 and P 3 , respectively, and which is configured so that under the condition that the I/O ports P 1 to P 4 are matched, a high-frequency signal fed via the I/O port P 1 is divided between the I/O ports P 2 and P 3 and the divided two signals are output 90° out of phase with each other but no signal is provided to the I/O ports P 4 , there are provided SPST switches 7 and 8 responsive to external control to control electromagnetic connections or coupling across a plane of symmetry 5 of the quadrature hybrid circuit passing through intermediate points of symmetry 23 and 24 of the third and fourth two-port circuits 21 and 22.

Enhanced local access in mobile communications using small node devices

Abstract: A hybrid user equipment and small-node device data offloading architecture is provided. In this hybrid architecture, the small-node device includes a backhaul link to a telecommunication network and/or the Internet. The user equipment can send and receive data through the small-node device using the backhaul link.

Base station and mobile station

Abstract: One aspect of the present invention relates to a base station wherein either resource blocks resulting from division of a system bandwidth into blocks of consecutive frequency subcarriers or distributed type resource blocks consisting of frequency subcarriers discretely distributed within the system bandwidth and resulting from segmentation of the resource blocks into multiple resource blocks are assigned to mobile stations, the base station including: a scheduling unit configured to assign either the resource blocks or the distributed type resource blocks to the mobile stations at a predefined assignment cycle based on respective downlink reception channel states transmitted from the mobile stations.

Media process server apparatus and media process method therefor

Abstract: A media process server apparatus has a speech synthesis data storage device for storing, after categorizing into emotions, data for speech synthesis in association with a user identifier, a text analyzer for determining, from a text message received from a message server apparatus, emotion of text, and a speech data synthesizer for generating speech data with emotional expression by synthesizing speech corresponding to the text, using data for speech synthesis that corresponds to the determined emotion and that is in association with a user identifier of a user who is a transmitter of the text message.