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.

Foldable mobile terminal device

Abstract: The present provides a mobile terminal device includes first and second housings foldably coupled to each other by a hinge portion, and the first housing can turn in the direction orthogonal to the unfolding/folding direction. The mobile terminal device also includes a first camera provided for a surface opposed to said second housing in a state that the device is folded, and a second camera provided for a surface of the first or second housing on the opposite side to the surface having the first camera, when the two housings are unfolded at an angle of about 90° and the first housing turns at an angle of about 90° to the second housing, and a sensor for detecting a positional relation between the two housings according to a change of the angle between the two housings. According to the detected position, operations of the first and second camera are stopped/started.

Rate Balancing in Multiuser MIMO OFDM Systems

Abstract: Recently, the capacity region of the Gaussian broadcast channel has been characterized. For a given transmit power constraint, those points on the boundary of the capacity region can be regarded as the set of optimal operational points. The present work addresses the problem of selecting the point within this set that satisfies given constraints on the ratios between rates achieved by the different users in the network. This problem is usually known as rate balancing. To this end, the optimum iterative approach for general MIMO channels is revisited and adapted to an OFDM transmission scheme. Specifically, an algorithm is proposed that exploits the structure of the OFDM channel and whose convergence speed is essentially insensitive to the number of subcarriers. This is in contrast to a straightforward extension of the general MIMO algorithm to an OFDM scheme. Still, relatively high complexity and the need of a time-sharing policy to reach certain rates are at least two obstacles for a practical implementation of the optimum solution. Based on a novel decomposition technique for broadcast channels a suboptimum non-iterative algorithm is introduced that does not require time-sharing and very closely approaches the optimum solution.

Wireless communication system, wireless communication device, wireless reception device, wireless communication method, and channel estimation method

Abstract: A wireless communication system is disclosed that transmits a feedback signal containing a channel estimate value between a first wireless communication device and a second wireless communication device. The first wireless communication device that transmits the feedback signals includes: a channel estimation unit that receives signals containing pilot signals, and determines the channel estimate value of a wireless link; a multiplier that multiplies a pilot signal by the channel estimate value; and a multiplexer that multiplexes an output signal from the multiplier with another pilot signal, to generate the feedback signal. The second wireless communication device that receives the feedback signal includes: a separator that separates the signals that are multiplexed in the feedback signal; and channel estimation units that determine the channel estimate value of the wireless link, based on the separated signals.

Relay apparatus for relaying a data packet to be transmitted from a first partner transceiver to a second partner transceiver

Abstract: A relay apparatus for relaying a data packet to be transmitted from a first partner transceiver to a second partner transceiver having a receive unit for receiving the data packet and for receiving an acknowledgement packet to be transmitted from the second partner transceiver to the first partner transceiver when the second partner transceiver has successfully received the data packet. The relay apparatus further having a help detector for providing a help indicator if a help necessitated situation is detected and a transmit unit for transmitting the data packet in response to the help indicator. The help necessitated situation is detected based on whether a first communication link between the relay apparatus and the second partner transceiver is better than a second communication link between the first and second partner transceivers, the second communication link being evaluated by an information being available from the data packet.

Enablers for Energy Efficient Wireless Networks

Abstract: Mobile communications are increasingly contributing to global energy consumption. The EARTH (Energy Aware Radio and neTworking tecHnologies) project tackles the important issue of reducing CO2 emissions by enhancing the energy efficiency of cellular mobile networks. EARTH is a holistic approach to develop a new generation of energy efficient products, components, deployment strategies and energy-aware network management solutions. In this paper the holistic EARTH approach to energy efficient mobile communication systems is introduced. Performance metrics are studied so to assess the theoretical bounds of energy efficiency and the practical achievable limits. Moreover, various deployment strategies focusing on their potential to reduce energy consumption are studied, whilst providing uncompromised coverage and user experience. This includes heterogeneous networks with a sophisticated mix of different cell sizes, which may be further enhanced by energy efficient relaying and base station cooperation technologies. Finally, scenarios leveraging the capability of advanced terminals to operate on multiple radio access technologies (RAT) are discussed with respect to their energy savings potential.