Abstract:
Some OFDM symbols transmitted temporally continuously by a base station include data signals that are not orthogonal to each other and are directed to user devices. A reference signal is arranged in the OFDM symbols temporally intermittently. The base station determines, according to reception qualities at user devices, downlink data signal transmission powers for transmitting downlink data signals. The base station reduces a downlink data signal transmission power in an OFDM symbol in which the reference signal is arranged to be lower than a downlink data signal transmission power in an OFDM symbol in which the reference signal is not arranged. The base station determines a downlink reference signal transmission power to be higher than the downlink data signal transmission power of a data signal in the OFDM symbol in which the reference signal is not arranged.
Abstract:
A base station connected to a user apparatus in a radio communication system is provided. The base station includes a receiving unit configured to receive from an interference base station first control information which is used by the user apparatus for reducing an uplink interference signal from one or more cells formed by the interference base station or from another user apparatus, a generation unit configured to generate second control information based on one or more pieces of the first control information received from the interference base station, and a transmitting unit configured to transmit the second control information to the user apparatus by a downlink control signal.
Abstract:
A user device receives, from a base station, a radio signal in which non-orthogonal signals are mixed. The user device recognizes, based on information transmitted from the base station, a parameter associated with the location of the user device. When the user device is at the edge of the cell area of the base station, a demodulator of the user device demodulates, as a signal directed to the user device, the radio signal in which an interference signal component has been suppressed by an interference rejection combining processor of the user device and a non-orthogonal signal canceller of the user device does not operate. When the user device is within the cell area and is not at the edge of the cell area, until the demodulator demodulates the signal directed to the user device, the interference rejection combining processor suppresses an interference signal component in a non-orthogonal signal outputted from the non-orthogonal signal canceller and the demodulator demodulates the non-orthogonal signal in which the interference signal component has been suppressed by the interference rejection combining processor.
Abstract:
In a radio communication system in which a high-power base station and a low-power base station collaborate for inter-cell interference control, the downlink transmission power at the high-power base station is suitably controlled. The high-power base station executes wireless transmission to the user terminals using resources that are the same as resources used by the low-power radio base station. A transmission power controller of the radio base station uses a first downlink transmission power at first resources and uses a lower second downlink transmission power at second resources. The transmission power controller adjusts the second downlink transmission power in accordance with the number of user terminals capable of executing interference rejection combining, the downlink traffic amount for user terminals capable of executing interference rejection combining, or the number of downlink resource blocks allocated to user terminals capable of executing interference rejection combining.
Abstract:
A user device includes a receiver configured to receive information indicating a ratio between a downlink data signal transmission power for an OFDM (orthogonal frequency division multiplexing) symbol in which a CRS (cell-specific reference signal) is not arranged and a downlink data signal transmission power for an OFDM symbol in which a CRS is arranged; and a controller configured to calculate a downlink data signal transmission power based on the information.
Abstract:
A base station, according to received qualities at user devices, allocates a downlink transmission power to each user device. The base station transmits a mixed data signal in which data signals mutually not orthogonal and each addressed to a corresponding user device are mixed. Control signals are transmitted to user devices to enable each user device to decode a data signal addressed to the user device using a control signal corresponding to the user device. Each control signal is scrambled by the identifier of the corresponding user device. A control signal for a first user device to which a first data signal is addressed includes information indicating the identifier of a second user device to which a second data signal mixed with the first data signal is addressed. The first user device is thus enabled to descramble a control signal for the second user device.
Abstract:
A user apparatus for use in a radio communication system, including: an successive interference cancelling reception unit configured to obtain a desired signal by successively canceling an interference signal that becomes interference to the desired signal from a received signal that the user apparatus receives; and an ordering determination unit configured to determine an order of interference signals to be successively canceled by the successive interference cancelling reception unit, wherein the ordering determination unit determines the order based on reception quality for each interference signal.
Abstract:
A user apparatus for use in a radio communication system, including: an successive interference cancelling reception unit configured to obtain a desired signal by successively canceling an interference signal that becomes interference to the desired signal from a received signal that the user apparatus receives; and an ordering determination unit configured to determine an order of interference signals to be successively canceled by the successive interference cancelling reception unit, wherein the ordering determination unit determines the order based on reception quality for each interference signal.
Abstract:
A base station connected to a user apparatus in a radio communication system is provided. The base station includes a receiving unit configured to receive from an interference base station first control information which is used by the user apparatus for reducing an uplink interference signal from one or more cells formed by the interference base station or from another user apparatus, a generation unit configured to generate second control information based on one or more pieces of the first control information received from the interference base station, and a transmitting unit configured to transmit the second control information to the user apparatus by a downlink control signal.
Abstract:
A mobile communication terminal calculates an interference rejection combining reception weight matrix so as to reduce interference with a desired beam by another beam, in which the desired beam is a beam of radio waves transmitted from a desired base station. The mobile communication terminal estimates an interference and noise power expected when the IRC is implemented based on the interference rejection combining reception weight matrix and calculates a signal-to-interference-plus-noise ratio expected when the IRC is implemented based on the interference and noise power. The mobile communication terminal measures or calculates received signal qualities relative to radio waves received from a plurality of base stations, to compensate for the signal-to-interference-plus-noise ratio or the interference and noise power.