Abstract: A method and a system is disclosed for controlling a sleep mode in broadband wireless access communication system. The subscriber terminals are managed by grouping the subscriber terminals in a broadband wireless access communication system, so an efficiency for controlling the sleep mode of the broadband wireless access communication system may increase. A further advantage is provided that each point of time for transmitting a paging message of each group is established differently from each other within a unit time slot for controlling the sleep mode, such that subscriber terminals are managed according to groups. Another advantage is provided that the base station can previously find subscriber terminals awaking at each point of time for transmission the paging message of each other from among subscriber terminals having the sleep mode, so an efficiency for controlling the sleep mode of the broadband wireless access communication system may increase.

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 receiving station (bit error rate in the transmitted data units of the transmitting station) and taking into account the current network loading are selected for transmission of data units.

Abstract: Disclosed is an apparatus and a method for effectively allocating frequency resources in a mobile communication system. The method includes: determining a first offset of a preset frequency band from among all frequency bands, determining a second offset corresponding to a symbol unit in the preset frequency band, and allocating frequency resources to data, the frequency resources corresponding to a sum of the first offset and the second offset.

Abstract: In a communication system using an Orthogonal Frequency Division Multiple Access (OFDMA) scheme, at least one value mapped to the number of threshold subchannels is compared with the number of subchannels allocated to a signal transmission apparatus in an associated Orthogonal Frequency Division Multiplexing (OFDM) symbol when transmission data including m bits is input. In response to a comparison result, (m?k) bits are generated from the transmission data using at least one of clipping and rounding. The (m?k) bits are converted to an analog signal and the analog signal is transmitted. The number of threshold subchannels is preset to determine whether to use clipping, rounding or both.

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 reducing an error vector magnitude in an orthogonal frequency division multiplexing (OFDM) receiver. The method includes the steps of inputting a receiving symbol including a guard interval and an effective symbol interval following the guard interval, in which a front portion of the guard interval and a rear portion of the effective symbol interval have windowing intervals corresponding to windowing of a transmitter, and replacing a signal of the rear windowing interval with a signal of an interval between the front windowing interval and the effective symbol interval, thereby outputting a signal of the effective symbol interval, which substitutes for a signal of the rear windowing interval, to a fast Fourier transform (FFT) section.

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 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: In an orthogonal frequency division multiplexing (OFDM) system, channel estimates of pilot subcarriers in a current input symbol are input, and time domain channel estimation for data subcarriers positioned between adjacent pilot subcarriers is performed by linear interpolating channel estimates of the adjacent pilot subcarriers associated with each of the pilot subcarriers in the current input symbol during a time interval of the current input symbol.

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: 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 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: 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: A method for controlling an operation mode of a terminal in a broadband wireless access communication system. In the method, the operation modes of the terminal is subdivided, such that it is possible to effectively reduce power consumption of the terminal. In particular, the method allows the terminal to operate in the inactive mode in which the terminal having no traffic with a base station more than a predetermined time returns a CID of the terminal to the base station and keeps only a downlink with the base station, so that it is possible to prevent power of the terminal from being consumed during the sleep mode. Additionally, because a CID is not assigned to the terminal in the inactive mode, resources of the base station are efficiently used.

Abstract: An apparatus and method for estimating a frequency offset using a preamble signal having a periodically repeated structure. According to the apparatus and method, the sum of or the difference between an input signal and a delay signal is calculated without obtaining a simple correlation value between the input signal and the delay signal, and then a correlation value between a calculated signal and the delay signal is obtained. Accordingly, the implementation complexity of the circuit and the power consumption are reduced, and thus, the battery cycle of a terminal provided with the frequency offset estimating circuit can be increased.

Abstract: Disclosed is a system and method for transmitting and receiving hybrid automatic repeat request (HARQ) buffer capability information in a broadband wireless access communication system. According to the system and method, a mobile station detects its own HARQ buffer capacity, and transmits a message including information about the detected HARQ buffer capability to a base station. The base station receives the message and determines the amount of a transmission signal to be allocated to the mobile station based on the HARQ buffer capability, so that it is possible to operate a HARQ scheme in accordance with the HARQ buffer capability of the mobile station.

Abstract: Disclosed is a communication system for a software upgrade, including a user terminal (UT) for transmitting an IP address assignment request message containing software information of the UT an upgrade-providing server including upgrade data regarding every software of the UT; and a server for determining whether or not software upgrade of the UT is necessary with reference to the software information when the request message is received, and transmitting an address and upgrade information of the upgrade-providing server to the UT when the software upgrade is necessary.

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 an apparatus and a method for transmitting/receiving synchronization mode information in a wireless communication system. A transmission apparatus in the wireless communication system includes a mode information creating unit for creating operation mode information based on a determined utilized bandwidth, and a preamble generating unit for outputting a frequency domain preamble signal including the created operation mode information. A reception apparatus includes a signal receiving unit for receiving a frequency domain preamble signal, a bandwidth determining unit for determining a utilized bandwidth, and a mode information detecting unit for detecting operation mode information from the frequency domain preamble signal according to the determined utilized bandwidth.

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.