Abstract: A transmission device to be applied to a communication system configured to carry out multi-user MIMO downlink communication, includes a precoder configured to apply transmission precoding processing, a nonlinear processor configured to carry out successive interference cancellation, a beam forming controller configured to form a plurality of beams and to control a beam radiation direction, and a user ordering processor configured to estimate a positional relationship among the plurality of user terminals from radiation direction information on each of the beams, order users in ascending order of a distance from a specific user, and determine a pairing of a transmission target user and an interference permissible user. The precoder determines two users of the transmission target user and the interference permissible user for each user based on the pairing result, and carries out null steering for users other than the two users, to thereby carry out the transmission precoding processing.

Abstract: A management server includes a processor and a storage that stores correlation information in which a category into which content is classified, location information, and an access frequency are correlated with one another. The processor acquires access information on an access from a wireless terminal to a content server via an access point and a network, a content requested by the wireless terminal, and location information corresponding to the accessed access point, updates the correlation information by rewriting the access frequency corresponding to a category to which the requested content belongs and the acquired location information, according to the access information, specifies a category and location information such that an access frequency related to the category and location information in the updated correlation information satisfies a criterion, and stores a content belonging to the category in a cache area of an access point corresponding to the location information.

Abstract: A storage device includes a storage unit, an interface that is physically connectable to a network, and a controller. The controller is configured to establish a first logical communication path via the interface in a first communication software layer, through which data is read from and stored in the storage unit, and a second logical communication path via the interface in a second communication software layer higher than the first communication software layer, through which meta information for controlling access to the storage unit is communicated.

Abstract: A LLR calculation unit includes a range detection unit that detects a range in which a received signal resulting from a modulo operation is present among a plurality of ranges defined on the basis of a boundary value in the modulo operation; a coefficient determination unit that determines a coefficient to be used for calculation of a log-likelihood ratio for a most significant bit in quadrature amplitude modulation of the received signal resulting from the modulo operation on the basis of a result of detection by the range detection unit; and an LLR computation unit that calculates the log-likelihood ratio for the most significant bit by using the received signal resulting from the modulo operation and the coefficient.

Abstract: A distributed antenna system includes a plurality of first antenna groups and a plurality of second antenna groups. The first antenna groups include a plurality of first antennas which forms beams in a first direction along a mobile station track and transmits identical signals at identical frequencies. The second antenna groups include a plurality of second antennas which forms beams in a second direction and transmits identical signals at identical frequencies. The first antennas and the second antennas are installed to face each other across the mobile station track. Each of the first antenna groups uses a frequency different from a frequency used in another first antenna group adjacent thereto, each of the second antenna groups uses a frequency different from a frequency used in another second antenna group adjacent thereto, and two frequencies are used by the first antenna groups and the second antenna groups in total.

Abstract: A distributed antenna system includes a plurality of antenna groups which includes first antennas and second antennas. The first antennas form beams in a first direction along a mobile station track and transmit identical signals at identical frequencies. The second antennas form beams in a second direction opposite to the first direction and transmit identical signals at identical frequencies. The antenna groups are installed on one side of the mobile station track.

Abstract: Provided is a wireless communication device, which is configured to: execute, for each of a plurality of counterpart wireless communication devices to be targets, first processing for determining a maximum number of assignable transmission streams based on transmission line quality information with respect to each of the plurality of counterpart wireless communication devices; execute, for each of the plurality of counterpart wireless communication devices, second processing for calculating a diversity order value of a single stream or each of a plurality of streams through use of the maximum number of transmission streams obtained by the first processing, and compare the calculated diversity order value of the single stream or each of the plurality of streams and a diversity order lower limit value set in advance to each other, to thereby determine a number of transmission streams; and determine the number of transmission streams obtained by the second processing as a finally-determined number of transmissio

Abstract: A base station serving as a transmission apparatus includes a plurality of transmission antennas capable of forming beams directed to a plurality of terminals, which are reception apparatus, and a precoder configured to perform outer precoding on transmission signals transmitted from the plurality of transmission antennas. The plurality of terminals include at least one first reception apparatus, which are transmission destinations of the transmission signals, and second reception apparatus, which are reception apparatus other than the first reception apparatus. The precoder performs outer precoding on the transmission signals transmitted from the plurality of transmission antennas so that received power in the second reception apparatus among the plurality of reception apparatus is equal to or less than a threshold.

Abstract: A distributed antenna system includes a plurality of first antenna groups and a plurality of second antenna groups. The first antenna groups include a plurality of first antennas which forms beams in a first direction along a mobile station track and transmits identical signals at identical frequencies. The second antenna groups include a plurality of second antennas which forms beams in a second direction and transmits identical signals at identical frequencies. The first antennas and the second antennas are installed to face each other across the mobile station track. Each of the first antenna groups uses a frequency different from a frequency used in another first antenna group adjacent thereto, each of the second antenna groups uses a frequency different from a frequency used in another second antenna group adjacent thereto, and two frequencies are used by the first antenna groups and the second antenna groups in total.

Abstract: An optical transmitter that transmits an optical signal includes a dither superimposing circuit configured to generate a dither signal, the dither signal being used to control an operation of the optical transmitter to output the optical signal, and a control circuit configured to control intermittent superimposition of the dither signal onto a target to be controlled.

Abstract: An optical transmitter has an optical modulator with a Mach-Zehnder interferometer, a pilot signal generator configured to generate a pilot signal to be superimposed on a drive signal for driving the optical modulator or on a substrate bias voltage applied to the optical modulator, and a controller configured to detect a ratio between a pilot component and a direct current component contained in a light output from the optical modulator and control at least one of an amplitude of the drive signal and a level of the substrate bias voltage such that the ratio becomes a constant value.

Abstract: A transmitting apparatus according to the present invention includes transmission antennas capable of forming a plurality of beams respectively directed to a plurality of terminals and a precoder unit that performs precoding on signals transmitted from the transmission antennas such that received power in the terminals excluding a desired terminal serving as a transmission destination of a transmission signal and two or more IUI terminals, which are the terminals other than the desired terminal, is equal to or smaller than a threshold.

Abstract: A transmitting apparatus includes transmission antennas capable of forming a plurality of beams respectively directed to a plurality of terminals and a precoder unit that performs precoding on signals transmitted from the transmission antennas such that received power in the terminals excluding a desired terminal serving as a transmission destination of a transmission signal and IUI terminals, which are the terminals other than the desired terminal, is equal to or smaller than a threshold.

Abstract: A communication system using hierarchical modulation and capable of flexibly adjusting line quality includes a transmission apparatus that hierarchically modulates and transmits signal sequences, a reception apparatus that hierarchically demodulates a received signal, and a hierarchization-parameter setting unit that sets hierarchization parameters. The transmission apparatus includes a hierarchical modulation unit that superimposes signals from layers while maintaining gray codes. The reception apparatus includes a hierarchical demodulation unit that demodulates and separates hierarchically modulated signals and detects signals from layers. The hierarchization-parameter setting unit sets a hierarchization ratio which is a signal power ratio used for superimposing a higher layer and a lower layer, a mapping pattern capable of selecting two patterns, and a mapping pattern mixing ratio indicating a ratio with which two mapping patterns are mixed.

Abstract: A transmission apparatus that transmits a block signal including a plurality of data symbols, includes: a data-symbol generation unit that generates a data symbol; a symbol arrangement unit that arranges the data symbol and a same-quadrant symbol such that one same-quadrant symbol that becomes a signal point in a same quadrant in a complex plane is inserted per block at a predetermined position in each block signal to generate a block symbol; a CP insertion unit that inserts a Cyclic Prefix into the block symbol; and an interpolation unit that performs interpolation processing on the block symbol on which CP insertion has been performed.

Abstract: A transmitting apparatus includes transmission antennas capable of forming a plurality of beams respectively directed to a plurality of terminals and a precoder unit that performs precoding on signals transmitted from the transmission antennas such that received power in the terminals excluding a desired terminal serving as a transmission destination of a transmission signal and IUI terminals, which are the terminals other than the desired terminal, is equal to or smaller than a threshold.

Abstract: A transmission apparatus that transmits a block signal including a plurality of data symbols, includes: a data-symbol generation unit that generates a data symbol; a symbol arrangement unit that arranges the data symbol and a same-quadrant symbol such that one same-quadrant symbol that becomes a signal point in a same quadrant in a complex plane is inserted per block at a predetermined position in each block signal to generate a block symbol; a CP insertion unit that inserts a Cyclic Prefix into the block symbol; and an interpolation unit that performs interpolation processing on the block symbol on which CP insertion has been performed.

Abstract: A transmitting apparatus according to the present invention includes transmission antennas capable of forming a plurality of beams respectively directed to a plurality of terminals and a precoder unit that performs precoding on signals transmitted from the transmission antennas such that received power in the terminals excluding a desired terminal serving as a transmission destination of a transmission signal and two or more IUI terminals, which are the terminals other than the desired terminal, is equal to or smaller than a threshold.

Abstract: According to one embodiment, a relay device that relays communication between an information request device which requests information and an information providing device which provides requested information. The relay device includes an interface to receive a signal transmitted by the information request device. The relay device includes a first circuitry to perform, using the signal, at least one of connection management of a network, authentication of the information request device, and authentication of a user of the information request device. The relay device includes a second circuitry to control allocation of storage areas included in a storage device, or an available range within which information saved in the storage area is able to be provided, when the first circuitry detects establishment of a connection to the network, disconnection of the connection, an authentication result, or a lapse of a valid connection time period.

Abstract: A transmission apparatus that transmits a block signal including a plurality of data symbols, includes a data-symbol generation unit that generates data symbols; a fixed-symbol arrangement unit that arranges a data symbol and a fixed symbol such that the fixed symbol is inserted at a predetermined position in the block signal to generate a block symbol; an interpolation unit that performs interpolation processing on the block symbol; and a CP insertion unit that inserts a Cyclic Prefix into a signal on which the interpolation processing has been performed to generate the block signal.