Abstract: Provided is a channel mode converting method of a wireless portable Internet system. When a diversity channel mode is converted into an Adaptive Modulation and Coding (AMC) channel mode, a radio resource for transmitting Channel Quality Information (CQI) is allocated without responding to a resource allocation request and a request between a terminal and an access point. Therefore, a delay time can be reduced on the channel mode conversion. In addition, a CQI channel for transmitting the existing channel quality information is released and a CQI channel for a new channel is allocated on the channel mode conversion. As a result, a time for changing the diversity channel CQI transmission to the AMC channel CQI transmission at the physical layer can be easily synchronized for transmitting the REP_RSP at the MAC.

Abstract: The present invention relates to a transmitter of an OFDMA system capable of controlling a gain for variation of subchannel allocation, and a method thereof. The transmitter includes a subchannel number determining unit, a modulator, a digital/analogue converter, and a gain controller controlling the gain. The subchannel number determining unit determines the number of subchannels in use according to communication environments, and the modulator modulates transmission data with reference to the number of subchannels determined by the subchannel number determining unit and outputs the modulated transmission data. The digital/analogue converter converts the transmission data into analogue data and transmits the converted analogue data through a transmit antenna. The gain controller controls gains of the transmission data according to gain values corresponding to the number of subchannels.

Abstract: The present invention provides an LDPC encoder, a channel encoder of a portable internet system including the LDPC encoder, and an encoding method thereof. The LDPC encoder according to the present invention generates a Costas array, shifts it, generates an analogous circulation parity check matrix having a repeated pattern from the shifted Costas array, and performs encoding by using the parity check matrix. With this LDPC encoder, complexity of encoding system may be reduced.

Abstract: A terminal of a portable Internet system comprising a medium access control (MAC) layer and a physical layer, the MAC layer comprising: a classifier classifying packets into classes; a delayer calling queue operating functions when a predetermined period of time is passed after the packets are classified by the classifier; a wait queue storing packets by the queue operating functions; and a packet processor processing the packet in the wait queue and transmitting the processed packet to the physical layer.

Abstract: A diversity transmission method and a transmitter of a base station using the same is provided in a mobile communication system. For this purpose, the diversity transmission method for controlling power of transmit antennas when the transmitter transmits a signal to a mobile terminal using a plurality of antennas includes (a) receiving feedback information concerning the antenna having the best channel status from the mobile terminal, (b) increasing power allocation of a selected antenna according to the feedback information by a predetermined amount and decreasing power allocation of a non-selected antenna by a predetermined amount, and (c) transmitting the signal to the mobile terminal using the power allocation controlled in (b).

Abstract: In a calibration apparatus in a communication system, a modulation unit calculates a reference signal by modulating a downlink signal, and a digital Intermediate Frequency (IF) unit converts the reference signal to an intermediate frequency signal. An up-converter converts the intermediate frequency signal to a Radio Frequency (RF) signal, and a down-converter generates a received signal for each of the paths from the RF signal to be transmitted through each path. A calibrator calculates a correction value for each path and a delay value by using the reference signal and the received signal for each path.

Abstract: An ICI cancellation iterative receiver and an ICI cancellation method in the wireless communication system is provided. In order to eliminate the Inter-carrier-interference (ICI) due to phase noise, an adaptive ICI cancellation scheme based on the wireless communication system is presented. In order to correct the contaminated preamble symbols due to phase noise, a first LMS adaptive filter in the receiver cancels the ICI. In the following data symbols of a frame, joint of the turbo decoder and channel estimation is provided. The complexity of the joint algorithm is analyzed and the algorithm can be implemented in the wireless communication system. The simulation results show that the performance can be improved dramatically.

Abstract: A terminal demodulation apparatus previously stores a received frame signal in a memory before inputting the same into a fast Fourier transform (FFT) unit, performs a demodulation to necessary information read from the corresponding memory, and has a separate data subcarrier memory and pilot subcarrier memory, and uses the signal demodulation method mixed with a subcarrier allocation method so as to easily demodulate various subcarrier allocation methods.

Abstract: A terminal includes a higher level bandwidth manager and a lower level bandwidth manager. The higher level bandwidth manager generates a guaranteed access request message including size information of a bandwidth corresponding to user data, transmits the guaranteed access request message, and transmits a user data transmission message including the user data. The lower level bandwidth manager uses the guaranteed access request message transmitted from the higher level bandwidth manager, generates a bandwidth request message using a guaranteed access, transmits the bandwidth request message to a base station, obtains the user data from the user data transmission message when receiving a bandwidth allocation signal from the base station, and transmits the user data to the base station.

Abstract: The present invention relates to a maximum ratio combining method of spatial-filtered received signals and an apparatus using the same. For this purpose the present invention provides a method for receiving signals by using a plurality of antennas that form a linear array antenna, multiplying a plurality of weight vectors by the received signals, summing the multiplication results for each weight vector, and combining the summing results by using maximum ratio combining. According to the present invention, signals are dividedly received by applying spatial filtering for a receiving direction of each signal and performance can be improved by combining the received signals by using maximum ratio combining. In addition, performance of an MRC-rake and a beam forming gain can be simultaneously acquired according to the present invention.

Abstract: Disclosed is a method and device for controlling a power saving mode for applying the sleep mode for saving power consumption to the mobility of subscriber stations in a mobile communication network and a wireless Internet system. Subscriber stations entering the sleep mode are constantly grouped, listening intervals of the subscriber stations for each group are not superimposed, the existence state of traffic in the subscriber stations is independently notified for each group, and the overhead of signaling messages is minimized when the traffic is notified to the subscriber station in the sleep mode.

Abstract: Disclosed is a traffic encryption key (TEK) management method for automatically generating a TEK for a multicast or broadcast service by a base station to periodically update a TEK used by a subscriber station. The base station transmits the first Key Update Command message for updating a group key encryption key (GKEK) for encrypting the TEK and the second Key Update Command message for updating the TEK to the subscriber station to update the TEK. The base station establishes an M & B TEK Grace Time which is different from a TEK Grace Time established by the subscriber station, transmits the first message including a new GKEK to the subscriber station through a primary management connection before the M & B TEK Grace Time, and transmits the second message including a new TEK encrypted with the new GKEK thereto through a broadcast connection after the M & B TEK Grace Time.

Abstract: The present invention relates to a method for searching and releasing an abnormal subscriber station in a wireless portable Internet system, and an apparatus using the same. The apparatus searches for an abnormal group including abnormal subscriber stations based on a ranging code provided in a periodic ranging process, and searches for an abnormal subscriber station by transmitting a connection maintenance message to subscriber stations included in the abnormal group so as to check an operation status of the respective subscriber stations. In addition, the apparatus releases a connection of an abnormal subscriber station. Therefore, waste of radio resources allocated to the abnormal subscriber station can be prevented, thereby achieving efficient resource management. Further, a secondary search process is performed only for subscriber stations included in an abnormal group, thereby preventing a system load from occurring when searching for an abnormal subscriber station.

Abstract: A mobile station transmitting and receiving method and a corresponding mobile station transmitter and receiver of a smart antenna system for forming uplink eigenbeams of the OFDM/TDD (orthogonal frequency division multiplex/time division duplex), wherein OFDM symbols are received from a base station through a downlink via multiple antennas (250) and an FFT (fast Fourier transform) is performed on the received OFDM symbols by the FFT units (270). By means of a channel estimator (290) the channels are estimated and a beam weight generator (310) generates respective beam weights from the channels of the respective pilot tones of the respective subcarriers according to the channel estimation result. A beam weight multiplier (230) forms the uplink beam by multiplying the respective beam weights with the output of the signal repeater (220) and IFFT units (240) generate respective OFDM symbols which are transmitted via multiple antennas (250) through an uplink.

Abstract: In a base station of an IEEE 802.16 Wireless MAN-based portable Internet system, a forward packet scheduling method and apparatus is provided. The portable Internet system portable Internet service includes a user terminal AT for providing a portable Internet service, a base station AP for supporting an inter-user terminal wireless access and network connection, and a packet access router PAR for performing a mobility control and packet routing function of each user terminal AT. The forward packet scheduler includes a packet-based subsidiary scheduling part for considering a real-time service and a user-based scheduling part for ensuring fairness and increasing system efficiency (throughput). After finishing the 2-step scheduling, the generated frame data are transmitted though a physical layer to a wireless user terminal.

Abstract: The present invention relates to an accounting method and an accounting apparatus in a mobile communication system. The amount of radio resources and traffic used by a mobile terminal of each subscriber accessing a base station can be measured and analyzed without changing a structure of the mobile communication system. In addition, since a provider who does not own an IP network and thus uses a leased network of an existing provider can measure and analyze the amount of traffic used by a mobile terminal in the leased network regardless of an IP network of the existing provider, a more precise accounting reference can be provided to the corresponding provider.

Abstract: A terminal main body of a communication terminal is supplied power from a battery pack through a DC signal path. The terminal main body communicates with at least one additional function module providing an additional function through a communication path connected to the DC signal path so as to provide the additional function to a user. Herein, the communication path is an AC signal path. That is, a signal transmitted/received between the terminal main body and the additional function module is an AC signal, and thus, the communication path can be compatible with the DC signal path providing the power. In addition, a plurality of additional function modules can be serially connected in the form of a serial communication bus, and therefore, a user can select a plurality of additional functions.

Abstract: A method for transmitting a handover security context of a first access point, when an access terminal from a service cell of a first access point is connected to a packet access router, to a service cell of a second access point connected to the packet access router, is provided. The handover security context transmitting method includes confirming whether a handover confirmation message transmitted from the access terminal has a security context therein; when the handover confirmation message has a security context therein, confirming whether the security context has security-related information therein; when the security context has security-related information therein, confirming whether the security context has a traffic-related key or a pairwise master key; and transmitting an information instruction message including the security related information confirmed in the security context, the security-related information, the traffic-related key, and the pairwise master key through the PAR to the second AP.

Abstract: In an Automatic Repeat reQuest (ARQ) method for recovering ARQ data by a target base station when handover of a mobile terminal is performed from a serving base station to the target base station in a portable Internet system is provided. First ARQ data, which includes a first service data unit (SDU), a first ARQ block sequence number, and a first sub-ARQ block sequence number, that are buffered in the serving base station are received and second ARQ data, which includes a second SDU, are received from the serving base station. The received first SDU is divided into ARQ blocks and is transmitted to the mobile terminal; and the received second SDU is divided into the ARQ blocks and is transmitted to the mobile terminal.

Abstract: The present invention relates to a mobile station of an OFDMA system and a transmit power control method thereof. The mobile station includes a modulator, a variable gain amplifier, a gain controller, and a power controller. The modulator modulates transmit data according to the number of allocated subchannels, and the variable gain amplifier amplifies the transmit data. The gain controller controls a gain of the transmit data inputted to the variable gain amplifier according to a subchannel gain value corresponding to the number of subchannels. The power controller calculates a power control gain for controlling power of the transmit data except the subchannel gain value based on the signal received from the base station and outputs the power control gain to the variable gain amplifier.