Abstract: A method and apparatus for processing time windowing to transmit a signal in a Broadband Wireless Access (BWA) communication system based on Orthogonal Frequency Division Multiple Access (OFDMA). A signal of a first interval included in a previous symbol prior to a current symbol is stored as a signal of a previous symbol interval. The current symbol includes a guard interval and an effective symbol interval subsequent to the guard interval. The current symbol is windowed by overlapping the stored signal of the first interval with a signal of a second interval included in the current symbol subsequent to the previous symbol. A windowed signal is transmitted.

Abstract: A Peak-to-Average Power Ratio (PAPR) reduction apparatus and method in an OFDM communication system are provided. In the PAPR reduction method, magnitude and phase components are extracted from transmission sample data. Peaks having magnitude components exceeding a threshold are detected by comparing the extracted magnitude components with the threshold. The highest of the peaks is detected and compared with the threshold. If the highest peak is greater than the threshold, the highest peak is updated.

Abstract: Disclosed is a method for controlling downlink power transmitted from a base station to subscriber stations in a mobile communication system employing an Orthogonal Frequency Division Multiple Access (OFDMA) scheme, in which data is carried from the base station to the subscriber stations by subchannels to each of which a plurality of subcarriers are assigned. The method includes the steps of receiving from the subscriber stations channel condition information of each of the subchannels together with information related to a subcarrier having a channel condition below a threshold from among at least one subcarrier included in each of the subchannels; calculating transmission power for each of the subchannels based on the received information; and transmitting each of the subchannels with the calculated transmission power, excluding the subcarrier having a channel condition below the threshold.

Abstract: A synchronization extraction apparatus for a communication system and a method thereof are disclosed. A frame synchronization is obtained in a manner that the sum of an input signal and a delay signal is obtained without obtaining a simple correlation value between the input signal and the delay signal, and then a correlation value between a summed signal and the delay signal is obtained. The synchronization extraction apparatus and method can reduce the implementation complexity and power consumption in obtaining the frame synchronization, and thus increase the battery cycle of a terminal provided with the synchronization extraction apparatus or method.

Abstract: Disclosed is a device and method that relates to radio engineering and especially to data transmission in a wireless local area network. The method improves the throughput of the wireless local area network, by selecting a transmission rate, data transmission mechanism and a fragment size which maximize the network throughput considering the receiving conditions on the receiver (bit error rate in the transmitted data units of the transmitter ) and taking into account the current network loading are selected for transmission of data units.

Abstract: An apparatus and method transmits data in a communication system. A buffer descriptor (BD) generator generates a BD making reference to constituent elements constituting a MAC protocol data unit (PDU), if there is a medium access control (MAC) service data unit (SDU) to be transmitted. A direct memory access (DMA) controller generates the MAC PDU from the MAC SDU according to the BD.

Abstract: A method and apparatus are provided for adaptively allocating pilots in a pilot-aided channel estimation system. A multipath delay is measured between a base station (BS) and a mobile station (MS). A distribution density of pilots of a signal to be transmitted between the BS and the MS is controlled. When the multipath delay is large, the pilot distribution density is relatively raised. However, when the multipath delay is small, the pilot distribution density is relatively lowered. The pilot distribution density is adaptively controlled according to the multipath delay, such that resources are effectively utilized and throughput is improved.

Abstract: Disclosed is an apparatus and method for estimating a start point of a frame in a wireless communication system. The method includes the steps of receiving a frame and estimating the start of the frame by searching for an interval or point of time during or at which a correlation between preambles is at its maximum. At this time, to in order to estimate the start of the frame, a cyclic prefix is used. Thus, a correlation between a cyclic prefix and the last interval of a symbol, which is the same as the cyclic prefix, is calculated and an interval or point of time having the maximum correlation is estimated as the start point of the cyclic prefix. Therefore, the start point of the frame can be accurately estimated based on the start point of the cyclic prefix.

Abstract: A method and apparatus for estimating interference and noise power in an orthogonal frequency division multiplexing/orthogonal frequency division multiple access/discrete multi-tone (OFDM/OFDMA/DMT) system is disclosed. A correlator correlates a plurality of sub-carriers with a preset reference sequence on an element-by-element basis and outputs a result of the correlation. A signal noise producer calculates a difference between a correlation value associated with each of the plurality of sub-carriers output from the correlator and a correlation value produced from at least one adjacent sub-carrier and outputs a result of the calculation. An interference and noise power producer produce interference and noise power from the difference between the correlation values calculated by the signal noise producer.

Abstract: Provided is a system and method for performing a ranging process in a communication system. If a Subscriber Station (SS) detects the insufficiency of UpLink (UL) resources for transmission of a Ranging Request (RNG_REQ) message during the ranging process, it transmits a UL resource allocation request message requesting additional allocation of the UL resources to a Base Station (BS) for additional transmission of the RNG_REQ message to cause the BS to additionally allocate the UL resources for the additional transmission of the RNG_REQ message.

Abstract: An apparatus and a method for allocating an uplink resource in a wireless communication system that uses a Half duplex-Frequency Division Duplex (H-FDD) scheme. The apparatus includes a controller and a message generator. The controller determines a resource allocation scheme enabling an F-FDD mobile station to allocate uplink bursts to a first group and a second group using one MAP message. The message generator generates a MAP message indicating the resource allocation scheme determined by the controller.

Abstract: In an apparatus for estimating a Carrier-to-Interference-and-Noise Ratio (CINR) in a communication system, received signals are blocked based on sub-carriers with similar channel characteristics. Interference and noise levels and true received signal levels are computed on a block-by-block basis from the blocked received signals. CINRs are estimated on a block-by-block basis using ratios between the computed interference and noise levels and the computed true received signal levels. The apparatus can estimate a CINR for all channels even when the channel characteristics of the sub-carriers of the received signals are not similar to each other.

Abstract: Provided is an apparatus and method for receiving a signal in communication system. The apparatus and method includes generating a particular log-likelihood ratio (LLR) value by demapping an input signal according to a particular demapping scheme among a plurality of demapping schemes; performing a control operation of buffering the particular LLR value in a particular LLR sub-buffer for buffering an LLR value generated according to the particular demapping scheme among the plurality of LLR sub-buffers for buffering an LLR value generated according to each of the plurality of demapping schemes; and performing a control operation of reading an LLR value buffered in an LLR buffer including the plurality of LLR sub-buffers.

Abstract: An apparatus and method are provided for estimating a Carrier-to-Interference-and-Noise Ratio (CINR) in a communication system based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In the communication system, all base stations boost a power level for a preamble or pilot by B dB. Accordingly, a received signal power level and a received interference level are boosted by B dB, but a noise level is not boosted. Transmission power for a preamble or pilot interval is boosted as compared with that for the data interval. After an interference and noise level is estimated from a preamble or pilot, the interference and noise level estimate of the preamble or pilot is corrected by taking into account a boosting level of the preamble or pilot.

Abstract: An apparatus and a method for estimating a carrier to interference and noise ratio (CINR) in a communication system. The CINR value is precisely estimated by removing the error floor value, which is caused by the inaccurate sliding average window SAW channel estimation value, from the CINR estimation value. Since the CINR value is precisely estimated, performance of the adaptive power control or the adaptive modulation and coding device is improved.

Abstract: Disclosed are an apparatus and a method for generating a preamble signal for cell identification in an OFDM mobile communication system. The method includes the steps of generating a Walsh code symbol for a cell identification by combining Walsh codewords having a predetermined length and generating the preamble signal through multiplying the Walsh code symbol by a pseudo noise (PN) code having a length identical to a length of the Walsh code symbol.

Abstract: Disclosed is a system and a method for provisioning service flows in broadband wireless access communication. In a broadband wireless access communication system, if a base station receives a registration request message from a mobile station, and if the base station inserts information about service flows to be provisioned by a base station into a registration response message and transmits the registration response message to the mobile station after the registration request message is received, the mobile station determines if the mobile station transits into a normal operation mode corresponding to the information and exactly recognizes a time point at which the mobile station goes into the normal operation mode.

Abstract: Disclosed is an apparatus and a method for performing a cell search in a wireless communication system. A subscriber station calculates the power of subcarriers according to their positions in a preamble signal of a frequency domain and identifies a segment of a cell to which the subscriber station belongs. Then, the subscriber station correlates PN sequences, which correspond to the segment of the cell that has been identified, with the preamble signal of the frequency domain. Therefore, the number of calculations for determining correlation values in a cell search is remarkably reduced.

Abstract: Disclosed is a system and a method for provisioning service flows in broadband wireless access communication. In a broadband wireless access communication system, if a base station receives a registration request message from a mobile station, and if the base station inserts information about service flows to be provisioned by a base station into a registration response message and transmits the registration response message to the mobile station after the registration request message is received, the mobile station determines if the mobile station transits into a normal operation mode corresponding to the information and exactly recognizes a time point at which the mobile station goes into the normal operation mode.

Abstract: A method and apparatus for providing a service from a voice-service dedicated terminal to a data-service dedicated terminal by using user identification information of a mobile terminal user in a wireless communication system are provided. The method includes generating a message including an identification of a receiving-side terminal and a service type of the message, and transmitting the generated message to a service server.