Abstract: A base station, a mobile station, a radio communications system, and a radio transmission method are disclosed. The base station includes a control information determining unit configured to determine control information that includes a spreading factor, the number of chip repetitions, and a phase unique to the mobile station, based on at least one of information about the type of cell environments in which the mobile station is present, information about the number of mobile stations that are present in the cell, information about information rate required by the mobile station, information about a type of traffic, information about a radio parameter of the mobile station, information about a propagation path condition, and information about interference from an adjacent cell, and configured to transmit the spreading factor, the number of chip repetitions, and the unique phase of the mobile station that is determined to the mobile station.

Abstract: A disclosed transmission apparatus comprises a switching portion that switches radio access methods; a frequency domain signal generation portion that allocates a radio resource to a spread chip sequence on which one of a fast Fourier transformation and a series/parallel conversion is performed in accordance with the switched radio accessed method, so as to generate a signal in a frequency domain; and a transmission signal generation portion that performs a fast inverse Fourier transformation on the signal in the frequency domain so as to generate a transmission signal.

Abstract: An apparatus for generating sets of radio parameters includes a first deriving unit deriving a set of radio parameters for specifying a symbol including an effective symbol part with the same period as the effective symbol part specified by another set of radio parameters and a guard interval part with a different period from the guard interval part specified by the other set of radio parameters. The apparatus further includes a second deriving unit deriving a set of radio parameters so that an occupancy proportion of the guard interval part in a single symbol specified by another set of radio parameters is equal to an occupancy proportion of the guard interval part in a single symbol specified by the other set of radio parameters.

Abstract: The object of the present invention is to provide a transmitter for multi-carrier transmission for allocating pilot channels to radio frames, in consideration of interference with other pilot channels. The present invention relates to the transmitter for multi-carrier transmission configured to transmit a plurality of sub-carriers having at least one pilot symbol duration. The transmitter according to the present invention comprises a pilot symbol allocater configured to allocate a plurality of pilot symbol patterns which are orthogonal to each other, to the at least one pilot symbol durations in at least two sub-carriers.

Abstract: An apparatus for generating sets of radio parameters includes a first deriving unit deriving a set of radio parameters for specifying a symbol including an effective symbol part with the same period as the effective symbol part specified by another set of radio parameters and a guard interval part with a different period from the guard interval part specified by the other set of radio parameters. The apparatus further includes a second deriving unit deriving a set of radio parameters so that an occupancy proportion of the guard interval part in a single symbol specified by another set of radio parameters is equal to an occupancy proportion of the guard interval part in a single symbol specified by the other set of radio parameters.

Abstract: A base station configured to communicate with a mobile station includes a controlling-information transmitting unit and a receiving unit. The controlling-information transmitting unit is configured to transmit to the mobile station as a set of controlling information, an information set indicating an environment of a cell which is resided by the mobile station, or an information set indicating power of interference from surrounding cells, or an information set indicating a condition of propagation channel. The receiving unit is configured to receive a signal transmitted from the mobile station, based on said set of controlling information, via a variably-controlling process of a spreading factor and a number of chip repetitions.

Abstract: A radio transmitter-receiver wherein a pilot symbol is used in the transmitter that has undergone M-chip spreading on the frequency axis and N-chip spreading on the time axis by a spreading code of M×N chip length (where M and N are any integers equal to or greater than 2), and in the receiver, a spreading code that is not used in spreading said pilot signal is used as a despreading code to despread a received signal and then estimate noise and interference power. The spreading code that is used to spread the pilot symbol and the despreading code that is used in despreading are assigned so as to be orthogonal even if only in N chips on the time axis.

Abstract: A disclosed radio communications apparatus adaptively controls a modulation method and coding rate (MCS) of a data channel in accordance with received channel quality information (CQI). This apparatus includes a first data table indicating a first corresponding relationship of the MCS with respect to the CQI; a second data table indicating a second corresponding relationship of transmission power of a control channel with respect to the CQI; a first selection portion that accesses the first data table so as to select the MCS of the data channel in accordance with the received CQI; a second selection portion that accesses the second data table so as to select the transmission power of the control channel in accordance with the received CQI; and a transmission portion that transmits the data channel in accordance with the selected MCS and the control channel at the selected transmission power.

Abstract: With the object of efficiently transmitting a variety of different information signals by utilizing the multi-carrier characteristics of Multi-carrier/DS-CDMA, the present invention is characterized in that, when, in an uplink transmission from a plurality of mobile stations to a base station, the mobile stations transmit a preamble to the base station before transmitting an information symbol sequence, the mobile stations individually select a carrier from among a plurality of carriers, and, up until receiving a preamble receipt confirmation signal from the base station with a prescribed maximum number of preamble transmissions serving as an upper limit number; the mobile stations repeatedly transmit a preamble by means of the selected carrier and vary the transmission power used for the transmissions of each carrier.

Abstract: A disclosed downlink channel configuration method in a radio communication system includes a step of including a broadcast channel, a paging channel, and a downlink shared channel as transport channels; a step of including as a physical channel a physical downlink shared channel to which the downlink shared channel of the transport channel is mapped; and a step of sharing the downlink shared channel by plural users without using a dedicated channel separately allocated to each of the users. In a preferred embodiment, as the physical channels, there are further included a physical broadcast channel as an independent radio resource to which the broadcast channel of the transport channel is mapped and a physical paging channel as an independent radio resource to which the paging channel of the transport channel is mapped.

Abstract: In a radio communication system defining a plurality of bandwidths, mobile terminals of kinds respectively corresponding to the plurality of bandwidths are accommodated in the system, and a minimum transmission bandwidth of the plurality of bandwidths is set as a transmission bandwidth of a downlink common channel. Or, every mobile terminal accommodated in the radio communication system is provided with a capability for processing a bandwidth equal to or greater than a predetermined value, and equal to or more than two transmission bandwidths that are equal to or less than a predetermined value are set as a transmission bandwidth of a downlink common channel. In the latter case, the mobile terminal identifies a bandwidth of a received downlink common channel.

Abstract: The present invention is directed to a channel structuring method that includes a step of providing time frames segmented at a predetermined interval in communication channels of n subcarriers, a step of selecting a predetermined number of subcarriers from n subcarriers and a step of inserting a common control channel signal and a common pilot signal periodically into each of the time frames of the selected subcarriers.

Abstract: A base station includes: means that derives a transmission power of a mobile station based on receive quality of an uplink pilot channel; means that reports the derived transmission power to the mobile station; and means that receives a control channel transmitted by the mobile station according to the reported information. Accordingly, irrespective of transmission power history over a past continuous time, the mobile station receives an instruction on the transmission power from the base station each time when transmitting a packet so as to be able to adjust the transmission power.

Abstract: A wireless communications system includes a base station and multiple mobile stations performing wireless communication with the base station in a DS-CDMA scheme. Each of the mobile stations has a transmission unit configured to transmit a timing difference detection packet to the base station, prior to transmitting packet data. The base station has a transmission timing control unit configured to detect a difference in signal receive timing from the mobile stations based on the timing difference detection packet, produce transmission timing control information for each of the mobile stations based on the detection result, and supply the transmission timing control information to each of the mobile stations to cause the mobile stations to adjust the transmission timing of the packet data.

Abstract: The present invention is directed to a channel structuring method that includes a step of providing time frames segmented at a predetermined interval in communication channels of n subcarriers, a step of selecting a predetermined number of subcarriers from n subcarriers and a step of inserting a common control channel signal and a common pilot signal periodically into each of the time frames of the selected subcarriers.

Abstract: In a radio communication system, a downlink frequency band includes a plurality of frequency blocks including one or more carrier frequencies, and one or more frequency blocks are used for data transmission to a single user. A radio communication apparatus for use in the communication system has an evaluation unit evaluating the quality of a received signal for each frequency block and storing plurality of stored quality evaluations of the received signal, a comparison unit comparing the plural quality evaluations of the received signal, and a transmission unit transmitting a predetermined number of the quality evaluations of the received signal over an uplink control channel.

Abstract: The object of the present invention is to prevent continued reception of unreliable information symbols at the receiver apparatus 200 in the OFDM radio communication system, so that it is possible to improve transmission quality. The radio communication system according to the present invention comprises a transmitter apparatus 100 configured to estimate conditions of propagation paths used in the radio communication, arrange information symbols along the direction of the frequency axis in accordance with a predetermined pattern based on the estimated conditions of propagation paths, and transmit a radio communication signal including the arranged information symbols and a receiver apparatus 200 configured to receive the radio communication signal, and rearrange the information symbol included in the radio communication signal along the direction of the frequency axis in accordance with a reverse pattern to the predetermined pattern.

Abstract: An apparatus for determining uplink transmission parameters includes a reception unit receiving a channel quality indicator from a mobile station; a storage unit storing relationships among a channel quality indicator, a modulation scheme and a channel coding rate for an uplink, and one or both of transmission power and transmission bandwidth for a mobile station; a determination unit determining a set of transmission parameters based on the relationship; and a transmission unit transmitting the set of transmission parameters to the mobile station.

Abstract: A disclosed radio communications apparatus performs at least an automatic repeat request control and performs radio communications using a frame that occupies predetermined plural frequency bands. This apparatus includes a reception portion that receives feedback information about each of a plurality of frequency bands from a communications party, a determination portion that determines which frequency band among the plural frequency bands is to be used to retransmit a retransmission packet indicated by the feedback information, and a transmission portion that transmits the retransmission packet using. one or more determined frequency bands.

Abstract: A base station includes a control unit configured to avoid contention between a radio resource allocated to a transmission packet or a retransmission packet by a channel-condition-based scheduling unit and a radio resource allocated to a transmission packet or a retransmission packet by a persistent scheduling unit.