Abstract: A coordinated transmission method of the invention has the steps of selecting a directional pattern corresponding to an area in which a radio terminal locates, from among a plurality of directional patterns determined respectively corresponding to a plurality of resources in frequency domains where the plurality of directional patterns is configured so that a plurality of radio base stations surrounding the area transmits, to the area, directional beams of same frequency domain resources to face one another, while not transmitting the directional beams of the same frequency domain resources using the same frequency domain resources to areas adjacent to the area, and of distributing a signal to transmit to the radio terminal according to the selected directional pattern, determining a frequency domain and directions of directional beams regarding the distributed signal, and delivering the signal to each of the plurality of radio base stations that simultaneously transmits the signal to the radio terminal.

Abstract: A signal reception time period detector is disclosed. The signal reception time period detector includes a signal separation portion configured to decompose into signal components a received signal composed of plural signals which are overlapped at least partially in a period during which the received signal is transmitted, and a reception time period detection portion configured to detect a time period during which the signal components are received based on the signal components.

Abstract: In the communication system, a transmission signal based on the first radio access scheme is generated, and in the communication system a transmission signal based on the second radio access scheme different from the first radio access scheme is generated. A usage status of the frequency spectrum of the transmission signal based on the first radio access scheme, as well as the known parameters of the transmission signal based on the second radio access scheme, are determined by the pulse-shaping controller. Then, the pulse-shaping controller performs control so as to pulse-shape the transmission signal based on the first radio access scheme by means of the transmit filter on the basis of the result of the above determination, or performs control so as to pulse-shape the transmission signal based on the second radio access scheme by means of the transmit filter on the basis of the result of the above determination.

Abstract: A disclosed radio communication method includes precoding modulated information signal sequences to calculate transmit weight information, setting initial transmit power based on prior information including the calculated transmit weight information, generating an objective function of a user channel capacity for a constrained optimization problem based on the transmit weight information and the initial transmit power, generating a new objective function by adding a barrier function to the objective function, using an initial temporary barrier parameter to initiate iteration of an optimization operation for the new objective function, setting an initial barrier parameter based on comparison between the current and previous outputs, calculating transmit power to optimize the new objective function in accordance with an interior point method based on the initial transmit power and the initial barrier parameter and allocating the calculated transmit power to the respective transmit antennas.

Abstract: A communication device used in a first communication system under a frequency sharing environment where the first communication system and a second communication system establish communications within the same frequency band is disclosed. The communication device comprises a detector for detecting an interfering signal from the second communication system; and a determiner for determining transfer characteristics of a shaping filter according to a result of the detection, the shaping filter being used for a desired signal of the first communication system.

Abstract: There is provided a communication system capable of achieving a high usage efficiency of frequencies without the need for cooperation of multiplexed users. A communication system communicates over frequency channels set by dividing a frequency bandwidth assigned to the system allows interference between channels by overlapping the adjacent frequency channels with each other in the frequency domain, or a transmitting and receiving device, which transmits and receives a signal by allowing the interference between symbols at a waveform level for each channel to decrease the occupied bandwidth, is provided with ICI removal and ISI compensation filter 111 serving as either an ICI removal filter for removing the interference between channels or an ISI compensation filter for compensating the interference between symbols.

Abstract: A disclosed radio communication apparatus includes a preceding unit configured to precode multiple streams, a splitting unit configured to split the precoded streams into two or more stream sets each including one or more streams, a sub power optimization unit configured to execute an iterative transmit power optimization algorithm on each of the split stream sets to determine respective transmit power levels for the individual stream sets, a power optimization unit configured to execute the iterative transmit power optimization algorithm by using the determined transmit power levels as initial values for the iterative transmit power optimization algorithm to determine respective transmit power levels for the individual streams, and a transmission unit configured to transmit radio signals from individual transmit antennas at the determined transmit power levels.

Abstract: A disclosed radio communication apparatus includes a preceding unit, a optimum transmit power calculation unit and a transmission unit. The optimum transmit power calculation unit receives the transmit weight related information from the preceding unit and calculates a transmit power level to optimize an objective function in accordance with an interior point method. The objective function results from addition of a barrier function adjusted with a barrier parameter to an original objective function associated with a constrained optimization problem. The original objective function includes a function of respective channel capacities for individual users derived from the transmit weight related information. The optimum transmit power calculation unit adaptively updates a logarithm of the barrier parameter and uses a gradient obtained through a high-order derivative with the logarithm of the barrier parameter to calculate the transmit power level to optimize the resulting objective function.

Abstract: A disclosed radio communication apparatus transmits a radio signal to multiple users via multiple transmit antenna groups at appropriate transmit power levels, each of the transmit antenna groups including one or more transmit antennas, the transmit antenna groups having respective transmit power constraints. The apparatus includes a precoding unit configured to perform precoding on signals modulated for individual users and generate transmit weights, an optimum transmit power calculation unit configured to receive the transmit weights from the precoding unit and use components of the transmit weights and respective transmit power limit values for the transmit antenna groups to calculate an initial value for a transmit power optimization problem for calculation of the appropriate transmit power levels for the users, and a transmission unit configured to transmit radio signals at the calculated transmit power levels.

Abstract: A signal frequency band detection device is disclosed that is able to separately handle plural co-existing signals, and able to separately detect frequency bands used for transmission of these co-existing signals. The signal frequency band detection device includes a signal decomposition unit that decomposes a received signal into plural signal components with frequency bands of the signal components at least partially overlapping each other; and a frequency band detection unit that, based on respective electrical powers of the signal components, detects the respective frequency bands of the signal components.

Abstract: A wireless transmitter comprises ID signal storage module for storing an ID signal that identifies a group to which a data signal to be transmitted belongs and provides, for each group, second or higher-order statistic properties unique to each group; modulator for modulating the data signal; wireless signal ID assignment module for associating the modulated signal thus modulated with the stored ID signal and for generating a signal to be transmitted, by assigning second or higher-order statistic properties that correspond with the ID signal to the modulated signal that is associated with the ID signal; and wireless signal transmission module for wirelessly transmitting the signal thus generated.

Abstract: A signal reception time period detector is disclosed. The signal reception time period detector includes a signal separation portion configured to decompose into signal components a received signal composed of plural signals which are overlapped at least partially in a period during which the received signal is transmitted, and a reception time period detection portion configured to detect a time period during which the signal components are received based on the signal components.

Abstract: In the communication system, a transmission signal based on the first radio access scheme is generated, and in the communication system a transmission signal based on the second radio access scheme different from the first radio access scheme is generated. A usage status of the frequency spectrum of the transmission signal based on the first radio access scheme, as well as the known parameters of the transmission signal based on the second radio access scheme, are determined by the pulse-shaping controller. Then, the pulse-shaping controller performs control so as to pulse-shape the transmission signal based on the first radio access scheme by means of the transmit filter on the basis of the result of the above determination, or performs control so as to pulse-shape the transmission signal based on the second radio access scheme by means of the transmit filter on the basis of the result of the above determination.

Abstract: A communication apparatus used in a spectrum sharing environment in which multiple communication systems coexist using the same spectrum band is provided. The apparatus includes a transmission pulse shaper that performs bandwidth limitation on a pulse which is used to send data symbols; a monitoring unit that monitors in-band interference conditions from coexisting systems other than a target system to which the communication apparatus belongs, and availability of unused spectrum on adjacent channels of the target system; a controller that controls a pulse transmission period and a pulse width of the transmission pulse shaper based on the monitoring result; and a transmission unit that transmits the band-limited signal.

Abstract: A communication device used in a first communication system under a frequency sharing environment where the first communication system and a second communication system establish communications within the same frequency band is disclosed. The communication device comprises a detector for detecting an interfering signal from the second communication system; and a determiner for determining transfer characteristics of a shaping filter according to a result of the detection, the shaping filter being used for a desired signal of the first communication system.