The next-generation multimedia wireless communication systems that are being actively researched in recent years are required to process various pieces of information, such as video and radio data, as well as the initial voice-centered services at the higher data transmission rate.
Orthogonal Frequency Division Multiplexing (OFDM) capable of having a high data transmission rate has recently been in the spotlight. OFDM is a multi-carrier modulation scheme of dividing a frequency band into a number of orthogonal subcarriers and sending data. Orthogonal Frequency Division Multiple Access (OFDMA) is a scheme for combining Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Spatial Division Multiple Access (SDMA), or Code Division Multiple Access (CDMA) with OFDM and providing the multiplexing of multiple users.
A wireless communication system includes a Base Station (BS) and one or more Mobile Stations (MSs). The mobile station can be fixed or mobile and can be referred to as another terminology, such as a User Equipment (UE), a User Terminal (UT), a Subscriber Station (SS), or a wireless device. In general, the base station refers to a fixed station that communicates with the mobile stations, and it can be referred to as another terminology, such as a Node-B, a Base Transceiver System (BTS), or an access point. Hereinafter, uplink (UL) transmission refers to transmission from a mobile station or a relay station to a base station or transmission from a mobile station to a relay station. Downlink (DL) transmission refers to transmission from a base station to a mobile station or a relay station or transmission from a relay station to a mobile station.
A wireless communication system has a cell structure for an efficient system configuration. A cell refers to that a wide area is divided into small areas in order to efficiently use the frequency. In general, a base station placed at the center of the cell provides relay for mobile stations, and the cell refers to a service area provided by one base station.
If, in a multi-cell environment, neighbor cells having the OFDM/OFDMA system use the same subcarrier, it can become the cause of interference for users. This is called inter-cell interference. In particular, such inter-cell interference becomes a big problem to a mobile station or a relay station placed near the boundary of a cell. In downlink, a mobile station placed near the boundary of a cell is subject to strong interference from neighbor cells. In uplink, a mobile station or a relay station placed near the boundary of a cell provides strong interference to neighbor cells and also has a low transmission rate because of the loss of a path in a serving cell.
To reduce such inter-cell interference, different subcarriers can be used between neighbor cells. This method, however, is problematic in that radio resources that can be used by one base station are reduced.
A multi-cell cooperation method has been proposed to reduce inter-cell interference in a multi-cell environment. If the multi-cell cooperation method is used, the communication performance of mobile stations or relay stations placed near the boundary of a cell can be improved. Several discussions are in progress in relation to a method of transmitting and processing data using the multi-cell cooperation method.