Abstract: A method for transmitting data in an Orthogonal Frequency Division Multiple Access (OFDMA) system. The data transmission method includes determining a number of diversity tiles, each of which includes physically separated frequency resources; dividing an entire system band into diversity subbands including the diversity tiles and localized subbands including localized tiles, each of which includes physically adjacent frequency resources, when the determined number of diversity tiles is greater than a threshold; uniformly distributing the diversity tiles over the entire system band, and disposing the localized tiles in the remaining bands except for the diversity tiles, when the determined number of diversity files is not greater than the threshold; and transmitting data to multiple terminals over the configured diversity tiles and localized tiles using diversity transmission and localized transmission schemes.

Abstract: A method and apparatus for hopping of a Code Division Multiple Access (CDMA) control segment that carries control information in an Orthogonal Frequency Division Multiple Access (OFDMA) packet data mobile communication system are provided, in which a number of CDMA control segment hopping zones, each CDMA control segment hopping zone representing a frequency area for CDMA control segment hopping, is determined according to a total number of available tiles in the system and a number of tiles per CDMA control segment, each tile including a predetermined number of subcarriers, or according to a total number of available subcarriers in the system and a number of subcarriers per CDMA control segment. Start points of the hopping zones are determined using the number of the hopping zones, and the control information is transmitted or received in the CDMA control segment through hopping of the CDMA control segment over the hopping zones using the start points.

Abstract: A transmission/reception apparatus for transmitting packet data in an Orthogonal Frequency Division Multiplexing (OFDM) system. The apparatus includes a transmission module for generating a frame of an OFDM symbol including pilot tones using the packet data, and transmitting the frame to a wireless network; and a controller for changing at least one of a Pilot-to-Data Ratio (PDR) of the pilot tones and a density of the pilot tones based on a length of the frame. The reception apparatus includes a reception module for receiving a frame of an OFDM symbol including pilot tones from a wireless network, extracting the pilot tone from the received frame, performing channel estimation thereon, and demodulating the packet data; and a controller for receiving at least one of a PDR of the pilot tone and a density of the pilot tone, both of which are in proportion to a length of the frame, and controlling the reception module so that the channel estimation is performed, based on the received information.

Abstract: A method for supporting frequency hopping of a transmission apparatus by a reception apparatus in a wireless communication system supporting Hybrid Automatic Repeat reQuest (HARQ). The method includes determining whether a particular transmission apparatus has a need to perform hopping of allocating a different logical channel every Transmission Time Interval (TTI); and when there is no need to perform hopping every TTI, sending to the transmission apparatus a command to perform hopping every multiple TTIs, and simultaneously signaling information on a number of the multiple TTIs.