A first radio signal is received that was transmitted from a first antenna at a transmitter and a second radio signal transmitted from a second antenna at the transmitter different from the first antenna. The first radio signal is converted to a first orthogonal frequency division multiplexing (OFDM) frame signal, and the second radio signal is converted to a second OFDM frame signal. The first OFDM frame signal includes a grid of multiple frequency subcarriers and time periods, each time period with the frequency carriers corresponding to a first OFDM symbol such that the first OFDM frame includes first OFDM symbols. A first OFDM symbol is carried on frequency subcarriers during a time period, and the first OFDM frame includes first reference OFDM symbols located at corresponding time-frequency resource elements in the grid. Each resource element is defined by a one of the frequency subcarriers and one of the time periods. The second OFDM frame signal is similar and includes second reference OFDM symbols sharing the same grid of frequency subcarriers and time periods as the first OFDM frame. But the second reference OFDM symbols are located at corresponding time-frequency resource elements in the grid different than the corresponding time-frequency resource elements to which the first reference OFDM signals are located their respective OFDM frame signals. The first and second reference OFDM symbols are used to demodulate the first and second OFDM frame signals.

A first radio signal is received that was transmitted from a first antenna at a transmitter and a second radio signal transmitted from a second antenna at the transmitter different from the first antenna. The first radio signal is converted to a first orthogonal frequency division multiplexing (OFDM) frame signal, and the second radio signal is converted to a second OFDM frame signal. The first OFDM frame signal includes a grid of multiple frequency subcarriers and time periods, each time period with the frequency carriers corresponding to a first OFDM symbol such that the first OFDM frame includes first OFDM symbols. A first OFDM symbol is carried on frequency subcarriers during a time period, and the first OFDM frame includes first reference OFDM symbols located at corresponding time-frequency resource elements in the grid. Each resource element is defined by a one of the frequency subcarriers and one of the time periods. The second OFDM frame signal is similar and includes second reference OFDM symbols sharing the same grid of frequency subcarriers and time periods as the first OFDM frame. But the second reference OFDM symbols are located at corresponding time-frequency resource elements in the grid different than the corresponding time-frequency resource elements to which the first reference OFDM signals are located their respective OFDM frame signals. The first and second reference OFDM symbols are used to demodulate the first and second OFDM frame signals.

Systems and methodologies are described that facilitate efficient cell acquisition in a wireless communication system. In one aspect, a reference signal for use in cell acquisition can be constructed in a bandwidth-agnostic manner such that it contains a common central portion in a predetermined frequency band that is independent of a bandwidth utilized by an associated wireless communication system. The central portion can be constructed as a two-dimensional block in time and frequency that spans a default cell search bandwidth, a predetermined bandwidth specified by synchronization codes or other signals, or another suitable bandwidth. A reference signal can then be constructed form the central portion by tiling or expanding the central portion such that it spans the entire system bandwidth.

In order to provide a transmission device and transmission method with which a response signal for random access preamble transmitted from a preamble transmission device is efficiently transmitted, setting unit in base station sets a first resource candidate group, which enables terminal capable of receiving a latch response transmitted by demodulation reference signal (DMRS) transmission to be selected, and a second resource candidate group, which enables terminal incapable of receiving a latch response transmitted by DMRS transmission but capable of receiving a latch response transmitted by cell-specific reference signal (CRS) transmission to be selected. Control unit selects DMRS transmission as the latch response transmission method when a resource in which latch preamble has been received is included in the first candidate group, but selects CRS transmission as the latch response transmission method when the resource is included in the second resource candidate group.

Methods and apparatuses are described for wireless communications. Cells may be grouped into a plurality of cell groups. A time adjustment may be determined and applied to uplink transmission timing of a cell group. A transmission timing difference between a first cell group and a second cell group may be determined. If the transmission timing difference exceeding a threshold, one or more devices may stop transmitting uplink signals via one or more secondary cells and/or may stop applying the timing adjustment for a cell group.

Methods and apparatuses are described for wireless communications. Cells may be grouped into a plurality of cell groups. A time adjustment may be determined and applied to uplink transmission timing of a cell group. A transmission timing difference between a first cell group and a second cell group may be determined. If the transmission timing difference exceeding a threshold, one or more devices may stop transmitting uplink signals via one or more secondary cells and/or may stop applying the timing adjustment for a cell group.

A Node-B sends a polling message to a wireless transmit/receive unit (WTRU). The WTRU sends an uplink synchronization burst in response to the polling message without contention. The Node-B estimates an uplink timing shift based on the synchronization burst and sends an uplink timing adjustment command to the WTRU. The WTRU then adjusts uplink timing based on the uplink timing adjustment command. Alternatively, the Node-B may send a scheduling message for uplink synchronization to the WTRU. The WTRU may send a synchronization burst based on the scheduling message. Alternatively, the WTRU may perform contention-based uplink synchronization after receiving a synchronization request from the Node-B. The WTRU may enter an idle state instead of performing a handover to a new cell when the WTRU moves to the new cell. A discontinuous reception (DRX) interval for the WTRU may be set based on activity of the WTRU.

Disclosed is a wireless communication base station apparatus whereby it is possible to prevent degradation of throughput of LTE terminals, even when LTE terminals and LTE+ terminals are present together. In this apparatus, a setting section (105) sets in each subframe a resource block in which is arranged a reference signal that is employed solely by LTE+ terminals, based on the pattern of arrangement of reference signals employed solely by LTE+ terminals. In the case of symbols that are mapped to antennas (110-1) to (110-4), an arrangement section (106) arranges the characteristic cell reference signals employed by both LTE terminals and LTE+ terminals in all of the resource blocks in a single frame. In contrast, in the case of the symbols that are mapped to the antennas (110-5) to (110-8), the arrangement section (106) arranges in some of the resource blocks, that are set in accordance with the setting results input from a setting section (105), the characteristic cell reference signals that are employed solely by the LTE+ terminals.

The present invention is designed so that communication can be carried out adequately even when the bandwidth to use is limited to partial reduced bandwidths in a system bandwidth. According to an example of the present invention, a user terminal, in which the bandwidth to use is limited to a partial reduced bandwidth in a system bandwidth, has an acquiring section that acquires EPDCCH (Enhanced PDCCH) configuration information based on information that is reported from a radio base station without using a PDCCH (Physical Downlink Control Channel), and a receiving section that detects a user terminal-specific search space (USS: UE-specific Search Space) of an EPDCCH based on the EPDCCH configuration information.

The present invention is designed so that cross-carrier scheduling is carried out adequately even when the number of component carriers that can be configured in a user terminal is expanded compared to that of existing systems. A user terminal can communicate by using six or more component carriers, and has a receiving section that receives downlink control information including a carrier indicator field (CIF); and a control section that controls a receiving process of a downlink shared channel and/or a transmission process of an uplink shared channel in a predetermined component carrier based on the CIF, and the receiving section receives downlink control information including the same CIF value from different component carriers; and the control section determines the predetermined component carrier, considering an offset that is configured to a CIF value of each component carrier that transmits downlink control information including the CIF.