Sadayuki Abeta

Bio: Sadayuki Abeta is an academic researcher from NTT DoCoMo. The author has contributed to research in topics: Mobile station & Base station. The author has an hindex of 18, co-authored 57 publications receiving 1030 citations.

Toward LTE commercial launch and future plan for LTE enhancements (LTE-Advanced)

Abstract: As a promising radio access technology for next generation mobile communication systems, LTE (Long-Term Evolution) is being standardized by the 3rd Generation Partnership Project (3GPP) international standardization organization. LTE Release 8 has many advantages to the other systems, e.g., the peak throughput is 300Mbps in Downlink (DL) and 75Mbps in Uplink (UL), 2–3 time higher spectrum efficiency than Rel. 6 HSPA (High Speed Packet Access), very low latency around 5msec in RAN (Radio Access Network) and 100msec for connection setup time. With Release 8, the first version for LTE specification, being completed in March 2009, the LTE standard is now being developed towards commercialization in various countries in the world. This paper addresses the plan for LTE commercial launch in NTT DOCOMO and future plan for LTE Rel. 9 and LTE-Advanced (LTE Rel. 10 and beyond).

Receiver, transmitter, communication system, and method of communication

Abstract: A receiver, comprising a plurality of antennas configured to receive signals that are obtained by multiplying a plurality of data symbols transmitted over a plurality of data channels using spreading codes for each of the data channels, the data symbol being transmitted over a plurality of sub-carriers having different frequencies; a spreading code multiplier configured to multiply reception signals received by the plurality of antennas using spreading codes for the data channels corresponding to the reception signals; a weight controller configured to adjust antenna weights by which a reception signal received by each antenna is to be multiplied, and sub-carrier weights by which a reception signal received over each sub-carrier is to be multiplied; a weight multiplier configured to multiply the reception signals by the antenna weights and the sub-carrier weights adjusted by the weight controller; and a combining unit configured to combine the reception signals multiplied by the antenna weights and the sub-carrier weights at the weight multiplier among the antennas and over spreading code duration of the spreading codes.

Multi-carrier CDMA radio transmitting method and apparatus, and channel estimation method and apparatus for multi-carrier CDMA radio transmitting system

Abstract: A multi-carrier CDMA radio transmitting method replicates each information symbol and disposes thus-obtained information symbols along a frequency axis, multiplies the thus-obtained information symbols with a spreading code along the frequency axis, spreads the information symbols into components of a plurality of sub-carriers having different frequencies. The transmission rate of the information is changed by controlling the amount of information transmitted simultaneously by controlling the number of the information symbols to be used for spreading for the plurality of sub-carrier components for each user to which the information is to be transmitted.

Mobile communication method, wireless base station, and mobile station

Abstract: An objective is to improve communication quality by reducing an insertion loss or the like of a diplexer inserted to reduce a leakage from an uplink band to a downlink band in different bands. A mobile communication method according to the present invention includes the steps of: transmitting simultaneous transmission capability information from a mobile station UE to a radio base station eNB, the simultaneous transmission capability information indicating whether or not the mobile station UE can transmit uplink data signals via multiple carriers in the same sub-frame while performing uplink CA; performing scheduling for the mobile station UE by the radio base station eNB on the basis of the simultaneous transmission capability information; and performing communication by the mobile station UE on the basis of the scheduling information.

Radio transmission system and method, and transmitter apparatus and receiver apparatus used in the radio transmission system

Abstract: A radio transmission system is configured to, on the occasion of radio transmission of information between a transmitter and a receiver, perform the radio transmission of information using an orthogonal frequency and code division multiplexing transmission scheme of parallelly transmitting identical information by a plurality of sub-carriers. The radio transmission system has a spreading factor variable control transmitting device for parallelly converting information channel-coded at the transmitter, according to symbols transmitted simultaneously, and for spreading a sequence of parallelized symbols in at least one of a frequency direction and a time direction by a spreading code sequence of a designated spreading factor.

Touch-based authentication of a mobile device through user generated pattern creation

Abstract: A method, system, and apparatus of a touch-based authentication of a mobile device through user generated pattern creation are disclosed. In one embodiment, a method of a mobile device includes recognizing a tactile force on a touch screen without a visual aid as an unlocking gesture, storing the unlocking gesture to a memory of the mobile device, associating another tactile force on the touch screen with the unlocking gesture, and transforming the mobile device from an initial state to an unlocked state based on the association between the another tactile force and the unlocking gesture. The method may include transforming the mobile device to operate as a telephonic communication device in the unlocked state.

Resource allocation for device-to-device communications underlaying LTE-advanced networks

Abstract: The Long Term Evolution-Advanced (LTEAdvanced) networks are being developed to provide mobile broadband services for the fourth generation (4G) cellular wireless systems. Deviceto- device (D2D) communications is a promising technique to provide wireless peer-to-peer services and enhance spectrum utilization in the LTE-Advanced networks. In D2D communications, the user equipments (UEs) are allowed to directly communicate between each other by reusing the cellular resources rather than using uplink and downlink resources in the cellular mode when communicating via the base station. However, enabling D2D communications in a cellular network poses two major challenges. First, the interference caused to the cellular users by D2D devices could critically affect the performances of the cellular devices. Second, the minimum quality-of-service (QoS) requirements of D2D communications need to be guaranteed. In this article, we introduce a novel resource allocation scheme (i.e. joint resource block scheduling and power control) for D2D communications in LTE-Advanced networks to maximize the spectrum utilization while addressing the above challenges. First, an overview of LTE-Advanced networks, and architecture and signaling support for provisioning of D2D communications in these networks are described. Furthermore, research issues and the current state-of-the-art of D2D communications are discussed. Then, a resource allocation scheme based on a column generation method is proposed for D2D communications. The objective is to maximize the spectrum utilization by finding the minimum transmission length in terms of time slots for D2D links while protecting the cellular users from harmful interference and guaranteeing the QoS of D2D links. The performance of this scheme is evaluated through simulations.

Radio base station, user terminal, and radio communication method

Abstract: The present invention is designed to improve spectral efficiency in a radio communication system which can use non-orthogonal multiple access (NOMA). Steps are provided in which a radio base station configures one of a plurality of transmission mode including a first transmission mode, which groups a plurality of transmission methods including a transmission method to employ non-orthogonal multiple access (NOMA) and multiple-user multiple-input and multiple-output (MU-MIMO), and a second transmission mode, which groups a plurality of transmission methods including a transmission method to employ this NOMA and open-loop transmit diversity, and transmits a downlink signal for this user terminal based on the configured transmission mode.

Multiplexing of real time services and non-real time services for ofdm systems

Abstract: Transmitter and receiver units for use in an OFDM communications system and configurable to support multiple types of services. The transmitter unit includes one or more encoders, a symbol mapping element, and a modulator. Each encoder receives and codes a respective channel data stream to generate a corresponding coded data stream. The symbol mapping element receives and maps data from the coded data streams to generate modulation symbol vectors, with each modulation symbol vector including a set of data values used to modulate a set of tones to generate an OFDM symbol. The modulator modulates the modulation symbol vectors to provide a modulated signal suitable for transmission. The data from each coded data stream is mapped to a respective set of one or more “circuits”. Each circuit can be defined to include a number of tones from a number of OFDM symbols, a number of tones from a single OFDM symbol, all tones from one or more OFDM symbols, or some other combination of tones. The circuits can have equal size or different sizes. Different circuits can be used for full rate data (e.g., active speech) and low rate data (e.g., silence periods).

Terminal device, base station device, communication method, and integrated circuit

Abstract: According to the present invention, there are provided a base station device, a terminal device, a communication method, and an integrated circuit capable of performing communication more efficiently when the terminal device transmits an uplink signal based on scheduling by the base station device. The terminal device includes a setting unit that sets a first uplink-downlink configuration, a second uplink-downlink configuration, and a third uplink-downlink configuration, a reception unit that monitors a physical downlink control channel accompanied with a downlink control information format which is used to schedule a physical downlink shared channel in a downlink subframe based on the third uplink-downlink configuration and includes information making a request for transmitting a sounding reference signal, and a transmission unit that transmits or drops the sounding reference signal and transmit an HARQ-ACK for transmission with the physical downlink shared channel.