Abstract: Provided is an apparatus and method for estimating an uplink frequency offset in a wireless communication system. In a receiving apparatus of a wireless communication system using a random access channel composed of two equivalent sequences, the apparatus includes a channel receiver which extracts samples corresponding to the two sequences from an input random access channel signal; a correlator which computes first and second correlation values by correlating preceding and trailing samples among the samples output from the channel receiver with a predetermined sequence; and a frequency offset estimator which estimates a frequency offset by using a ratio of the second correlation value to the first correlation value output from the correlator.

Abstract: A method and apparatus for joint unicast using multi-user superposition coding in a wireless relay system are provided. A BS superposition-encodes first and second data messages directed to first and second MSs, respectively, scheduled at a current scheduling instant. The first and second data messages carry first and second information bit streams for the first and second MSs, respectively. The first MS has a relatively good direct link to the BS, and the second MS has a relatively bad direct link to the BS. The superposition-coded data is transmitted to the first MS and an RS connected between the BS and the first and second MSs. The RS receives the superposition-coded data from the BS, extracts the second information bit stream by decoding the superposition-coded data, and transmits a third data message carrying the second information bit stream to the first and second MSs.

Abstract: A system and method for transmitting and receiving a signal in a communication system using a relay scheme. A base station receives a first signal in a first time interval from a first mobile station which is at least one mobile station located in a third region which is a region where a first region which is a region of the base station itself overlaps with a second region which is a region of a relay station. The relay station receives a second signal in the first time interval from a second mobile station which is at least one mobile station located in a fourth region which is a region not overlapping with the first region in the second region, and receives the first signal from the first mobile station. The relay station transmits a third signal including the first signal and the second signal to the base station in a second time interval. The base station receives the third signal in the second time interval, and cancels the first signal from the third signal to detect the second signal.

Abstract: A transmitter for a mobile communication system based on an OFDM scheme and a method for controlling the same. The transmitter can implement a characteristic of a multiple access scheme based on an OFDM scheme, a characteristic of a CDMA scheme, and a characteristic of a frequency hopping scheme which has very strong resistance to the frequency selective fading.

Abstract: An apparatus for generating a preamble sequence in an orthogonal frequency division multiplexing (OFDM) communication system using A subcarriers in a frequency domain. A preamble sequence generator generates a length?M+N+k preamble sequence, where M+N+k is less than A, by combining a length?N Golay complementary sequence with a length?M Golay complementary sequence. An inverse fast Fourier transform (IFFT) processor assigns elements constituting the preamble sequence to the M+N+k subcarriers among the A subcarriers on a one-to-one mapping basis, assigns null data to remaining subcarriers excluding the M+N+k subcarriers from the A subcarriers, and then IFFT-transforms the assigned result into time-domain data.

Abstract: Disclosed is an apparatus and method for transmitting and receiving control information for a packet data channel in a mobile communication system supporting a high-speed packet data service and a circuit voice service. A base station generates control information indicating an encoder packet size, a code rate and the number of Walsh codes used for transmission of packet data to a mobile station, and transmits the generated control information over a packet data control channel. The mobile station receives the control information over the packet data control channel while receiving the packet data over the packet data channel, and decodes the received packet data according to a modulation order determined based on the received control information.

Abstract: A mobile communication system receives a reception signal of a reception signal, and performs a control operation such that a weight for generating a reception beam is calculated using a first technique if a difference between an error sum value at a current time and an error sum value at a previous time is greater than an absolute value of a first threshold or the error sum value at the current time is greater than or equal to a second threshold, and performs a control operation such that the weight is calculated using a second technique if the different between the error sum value at the current time and the error sum value at the previous time is less than or equal to the absolute value of the first threshold and the error sum value at the current time is less than the second threshold.

Abstract: A base station transmission apparatus for transmitting MAC (Medium Access Control) ID (Identification) information indicating a terminal to receive transmission packet data and length information of the transmission packet data in a mobile communication system for high-speed packet transmission, having an encoder for encoding a bit stream indicating the MAC ID information and generating coded symbols; a Walsh cover section for Walsh-covering the coded symbols from the encoder with a Walsh code based on the length information; and a Walsh spreader for spreading the Walsh-covered symbols from the Walsh cover section with a predetermined Walsh code.

Abstract: An apparatus and method for cooperative maximal ratio transmission in a BWA communication system are provided, in which a BS transmits a signal directed to a user terminal to an RS in a first time slot, the RS transmits the signal received from the BS to the user terminal in a second time slot, and the user terminal receives the signal from the RS.

Abstract: A method of orthogonalizing signals transmitted from a BS in an OFDMA system, at a transmitting end, includes a) performing encoding, interleaving and modulation on original information bits; b) allocating sub-carriers with equivalent intervals to a sub-channel, and dividing channels into two parts of a cell edge user channel and a center area channel; c) mapping modulated information symbols to the corresponding sub-carriers; d) performing orthogonalizing processing on the two parts of channels; e) for a user at an edge of the cell, according to result of step b), dividing an OFDM symbol into subsections of equal length; f) multiplying the subsections obtained from step e) by a corresponding orthogonalizing sequence of the cell; g) adding the OFDM symbols of the two parts together to form a whole OFDM symbol; h) adding a cyclic prefix for the system; and i) performing D/A conversion, RF processing and feedback over a transmitting antenna on a base-band signal.

Abstract: An apparatus and method for retransmitting data using an RS in a multi-hop network are provided. When retransmitting data in a BS, the BS transmits data and activates a timer therefor. The BS monitors receipt of a response message for the data until the timer expires. The BS receives the response message and, if it is a Non-Acknowledgement (NACK), determines whether an RS has successfully received the data with a BSN associated with the NACK. If the RS has not successfully received the data, the BS retransmits the data. If the RS has successfully received the data, the BS determines a retransmission entity. If the retransmission entity is the RS, the BS transmits a control message commanding retransmission to the RS, and if the retransmission entity is the BS, the BS retransmits the data.

Abstract: There are provided a transmitting/receiving apparatus and method for packet data service in a mobile telecommunication system. To determine the transmission format of packet data between a first format and a second format longer than the first format based on at least one channel state value received from a mobile station, received channel state values are sequentially stored. Then, the differences between all adjacent channel state values are calculated and summed. The sum is compared with a predetermined threshold. If the sum is greater than or equal to the predetermined threshold, the transmission format of the packet data is determined as the first format. If the sum is less than the predetermined threshold, the transmission format of the packet data is determined as the second format.

Abstract: Provided is an apparatus and method for efficiently transmitting packets to MSs in a BWA system using RSs. A BS uses an ESH to combines packets, which are to be transmitted through RSs to MSs, into a larger packet prior to transmission. Alternatively, the BS transmits packets, which are to be transmitted to MSs, to an RS without discrimination therebetween, and the RS determines whether the packets are to be transmitted to the MSs, prior to transmission.

Abstract: A method is provided for transmitting/receiving data in a communication system. The method includes measuring, by a Mobile Station (MS), states of channels which are allocated in a scheme prearranged with a Base Station (BS), and encoding measured channel state information in a scheme corresponding to an allocation scheme of the allocated channels; and configuring a message including the encoded channel state information, and transmitting the configured message to the BS.

Abstract: A method is provided for controlling power in a communication system. The power control method includes allocating a first data transmission region and a second data transmission region corresponding to a first communication scheme and second communication scheme; providing a communication service to a receiver through the first data transmission region, and receiving power control information from the receiver through the second data transmission region while providing the communication service; and adjusting a level of transmission power used for providing the communication service according to the received power control information, and providing the communication service to the receiver using the adjusted transmission power.

Abstract: An apparatus and method are disclosed for acquiring by a mobile terminal a pseudo-random noise (PN) sequence of a pilot signal received from a base station by means of a searcher, designating a phase of the acquired PN sequence as a reference phase to track the phase of the acquired PN sequence, and measuring an energy difference between an early path and a late path for the reference phase in a mobile communication system. In the apparatus and method, a first energy measurer measures a first energy value from a PN sequence with the reference phase, and a second energy measurer alternately measures energy values of the early path and the late path for the reference phase and outputs a second energy value.

Abstract: An apparatus and method for reducing MAP channel overhead in a broadband wireless communication system. In a Base Station (BS), a traffic classifier classifies transmission data into a first group and a second group according to user channel information and packet sizes of the transmission data. A MAP channel configure configures a MAP channel to include information about users of the first group and positions of data for the users, information indicating whether users of the second group have succeeded in random access in a second uplink data region of a previous frame, and information about resource reservation for a current frame for the second group. A channel mapper maps the first group to a first downlink data region and maps the second group to a second downlink data region according to the MAP channel.

Abstract: An apparatus and a method for estimating the channel state of each link in a wireless relay network having fixed RSs are provided. A source estimates a channel of a source-RS link and a channel of a source-destination link using pilot signals received from an Relay Station (RS) and a destination and the source monitors reception of a pilot signal including channel state information of an RS-destination link from the RS. Upon receipt of the pilot signal, the source estimates a channel of the RS-destination link using the pilot signal and the channel state information of the RS-destination link.

Abstract: Provided is a power control apparatus and method of a time division duplex (TDD) communication system. The power control apparatus includes an uplink power determiner for determining an uplink power value using a power control computation element of a current frame, which is acquired using a power control computation element of a prior frame and a power increase/decrease change estimated from a downlink, and a cell interference received from a base transceiver station (BTS); and an uplink power controller for controlling an uplink power by sending the uplink power value from the uplink power determiner to a transmitter.

Abstract: Provided are an apparatus and a method for providing a concurrent data service to an Mobile Station (MS) through a plurality of heterogeneous networks. In a method for providing a data service to an MS through different wireless networks, the MS measures channel qualities of at least one accessible wireless network and reports the measured channel qualities to an Internet Protocol (IP) packet controller. The IP packet controller selects wireless networks for data transmission on the basis of the reported channel qualities, distributes data destined for the MS, and transmits the distributed data to the selected wireless networks. The selected wireless networks receive the data from the IP packet controller and transmits the received data to the MS. The MS combines and interprets the data received from the selected wireless networks. Accordingly, it is possible to provide a seamless data service to the MS in service environments with a mixture of different wireless communication systems.