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.

Informed network coding for minimum decoding delay

Abstract: Network coding is a highly efficient data dissemination mechanism for wireless networks. Since network coded information can only be recovered after delivering a sufficient number of coded packets, the resulting decoding delay can become problematic for delay-sensitive applications such as real-time media streaming. Motivated by this observation, we consider several algorithms that minimize the decoding delay and analyze their performance by means of simulation. The algorithms differ both in the required information about the state of the neighborspsila buffers and in the way this knowledge is used to decide which packets to combine through coding operations. Our results show that a greedy algorithm, whose encodings maximize the number of nodes at which a coded packet is immediately decodable significantly outperforms existing network coding protocols.

Method and system for application load balancing

Abstract: In one aspect of the invention, a method for load balancing a mobile application among a plurality of devices forming part of at least one communication network is provided. The method includes storing the application on a server device of the network. The method also includes requesting the application from a client computing device of the network. The method further includes provisioning execution of the application on one of the server and client devices to optimize the user perceived performance of the application based on a set of application attributes. The application attributes includes performance attributes relating to wait times for user interface events of the application.

Mobile communication systems, mobile communication methods, base stations, mobile stations, and signal transmission methods in the mobile communication systems

Abstract: A mobile station is configured to measure receiving qualities of respective signals from a first antenna and a second antenna of a base station (S3, S5), store the results of the measurement, and request the base station to retransmit a signal from an antenna with a higher receiving quality, based on the stored measurement results, when an error is detected in received data thereafter (S10, S11, S12). The base station retransmits the data, using the antenna with the higher receiving quality (i.e., a base station antenna to yield the higher receiving quality at the mobile station) (S15). In another aspect, the mobile station measures a receiving quality of a signal and notifies the base station of the receiving quality. The base station selects a radio channel adapted to a receiving quality on the basis of the measurement result and transmits a signal, using the radio channel.

Channel estimation for OFDM with cyclic delay diversity

Abstract: For OFDM based systems using cyclic delay diversity (CDD), a multiple input channel is transformed to a single input channel, with increased frequency selectivity While CDD provides additional frequency diversity which can be utilized by the outer channel decoder, a conventional SISO channel estimator may have difficulties to track the increased dynamics of the received signal In this paper, an enhanced scheme for pilot-symbol aided channel estimation (PACE) is presented, which utilizes the properties of CDD

Radio communication method, user terminal, radio base station and radio communication system

Abstract: The present invention is designed so that it is possible to feed back channel state information (CSI) that is suitable for downlink communication in which 3D beams are used. The radio communication method of the present invention is a radio communication method to allow a radio base station to carry out downlink communication with a user terminal by using a 3D beam that is formed with a horizontal beam having directivity in a horizontal plane and a vertical beam having directivity in a vertical plane, and has the steps in which the radio base station transmits a plurality of measurement reference signals that are pre-coded using different precoding weights between a plurality of vertical beams, and the user terminal transmits channel state information that is generated based on the plurality of measurement reference signals, to the radio base station.