| Patent application number | Description | Published |
|---|
| 20080253333 | Call Admission Control Method for Use in Packet Based Communication System - Provided is a call admission control method for use in a packet based communication system, which can secure a handoff and a quality of service (QoS) by discriminating a new call and a handoff call and borrowing a shared bandwidth, a reserved bandwidth, and a bandwidth of other service according to kinds of services and their characteristics. The call admission control method includes the steps of: a) dividing frequency band into a reservation band and a shared band for communication service handoff call and multicast service handoff call, and determining whether a call admission request of users is a new call or a handoff call; b) when the call admission request is the new call, determining whether to accept the call admission request by allocating the shared band and a band borrowed from other service; and c) when the call admission request is the handoff call, determining whether to accept the call admission request by allocating the shared band, the reserved band, and the borrowed band according to services and bandwidth resources. | 10-16-2008 |
| 20080279142 | Method for Adaptive Transmit Power Allocation in Multiuser Ofdm System - Provided is a method for adaptive transmit power allocation in a multiuser OFDM system. The method includes: a) obtaining a channel gain for a predetermined bit period for each user at a predetermined time, and allocating all of available sub carriers to a user farthest separated among a plurality of users having a good channel gain; b) comparing a channel gain of the user allocated with the subcarrier at the step a) with an initial threshold value; c) allocating a transmit power uniformly to each of the sub carries allocated at the step a) using an Equal-power allocation algorithm if the channel gain is larger than the initial threshold value at the step b); and d) allocating a transmit power to each of the sub carriers allocated at the step a) using a water-filling power allocation algorithm if the channel gain is smaller than the initial threshold value at the step b). | 11-13-2008 |
| 20080298511 | Soft-Output Demodulation Apparatus and Method - Provided is a soft-output demodulation apparatus and method having a relatively low complexity and capable of acquiring a channel reliability value to be inputted to an iterative decoder, in a digital communication system. The apparatus includes: a storage unit for pre-determining and storing opposite-bit nearest constellation points corresponding to constellation points by dividing a constellation point region according to a modulation scheme; a quantizer for quantizing a channel reception signal; a region decider for deciding the nearest constellation point corresponding to the quantized channel reception signal; a reverse constellation point detector for detecting an opposite-bit nearest constellation point corresponding to the decided nearest constellation point from the values pre-stored in the storage unit; and a soft-output demodulation value calculator for calculating a soft-output demodulation value based on the nearest constellation point, the nearest constellation point of the opposite bit, and the channel reception signal. | 12-04-2008 |
| 20080317143 | Apparatus and Method for Correcting Iterative Residual Frequency and Phase in Turbo Coded Ofdm System - Provided is an iterative residual frequency and phase compensation apparatus for an OFDM system and a method thereof. The apparatus includes: a first classifying unit for classifying symbol sequences by each subcarrier wave; a soft-decision calculating unit for calculating a soft-decision value of a data symbol using a soft-decision reliability obtained from iterative decoding performed by the iterative decoder; a classifying unit for classifying the soft-decision values by a carrier wave; a frequency estimating unit for estimating a residual frequency error of each carrier wave using the soft-decision value; a phase estimating unit for estimating an average residual phase error using the soft-decision value; a frequency and phase compensating unit for compensating frequencies and phases for input symbols of each carrier wave using the estimated frequency error and the estimated phase error; and a buffer for temporally storing the compensated symbols to provide it to the first classifying unit. | 12-25-2008 |
| 20090241005 | METHOD FOR PACKET SCHEDULING IN SELECTIVE HYBRID ARQ - There is provided a method for packet scheduling in a selective hybrid automatic repeat request (HARQ) including the steps of: increasing a priority of a receiver buffer after a packet is transmitted to the receiver; receiving a feedback packet for the transmitted packet and determining whether the feedback packet is an ACK packet or a NACK packet; lowering the priority of the receiver buffer if the feedback packet is an ACK packet; determining whether the feedback packet is a NACK packet for initial transmission or the feedback packet is a NACK packet for retransmission if the feedback packet is the NACK packet, increasing the priority of the receiver buffer if the feedback packet is the NACK packet for the initial transmission, and lowering the priority of the receiver buffer if the feedback packet is the NACK packet for retransmission; and scheduling packets after calculating a priority of each receiver buffer by performing the priority increasing step to the determining step for all of receivers. | 09-24-2009 |
| 20100022238 | SIGNAL TRANSMISSION MECHANISM WITH DIVERSITY GAIN IN SATELLITE COMMUNICATION NETWORK - Provided is a satellite communication system for obtaining a diversity gain by transmitting a signal applied with STBC. When a signal transmission band of a link between a satellite and a terminal differs from that of a link between a satellite and a repeater, the satellite communication system includes: a satellite for transmitting a first signal encoded to STBC using a band of a link formed between the satellite to a terminal and transmitting a second signal encoded to STBC using a band of a link formed between the satellite to a repeater; and at least one of frequency transforming repeaters for receiving the second signal through the band of the link formed between the satellite to the repeater, transforming the received second signal to a signal with other frequency band, and transmitting the transformed second signal using a band of a link formed to a terminal. | 01-28-2010 |
| 20100027723 | TIME SYNCHRONIZATION METHOD AND FREQUENCY OFFSET ESTIMATION METHOD USING THE SAME IN OFDM NETWORK - Provided are a time synchronization method and a frequency offset estimation method using the same in an OFDM system. The time synchronization method using a preamble transmitted from a transmitter to a receiver in the OFDM communication network includes the steps of: a) calculating a moving sum of a first sequence and a second sequence obtained by a product of neighboring elements in a received signal when the received signal containing a preamble is received from the transmitter; b) estimating a location of the received signal corresponding to the moving sum having a maximum value; and c) acquiring a time synchronization with respect to the received signal, based on the estimated location, wherein the first sequence is obtained from a product of neighboring elements in the preamble and a correlation value obtained by correlating another sequence with the first sequence is smaller than a predetermined value. | 02-04-2010 |
| 20100050035 | METHOD FOR PREVENTING CONSECUTIVE PACKET ERRORS IN SELECTIVE HYBRID ARQ SYSTEM - Provided is a method for preventing consecutive packet errors in a transmitter by combining a hybrid automatic repeat request (HARQ) type II with a selective automatic repeat request (ARQ), including: transmitting a data packet from the transmitter to a receiver; when a negative acknowledgement (NACK) packet corresponding to the data packet is received from the receiver, checking stored information in the NACK packet wherein the stored information represent whether or not the data packet is stored in a buffer; when the data packet is stored in the buffer, transmitting a packet having parity bits to the receiver and storing the data packet in a retransmission queue; and when the data packet is not stored in the buffer, re-transmitting the data packet and maintaining the data packet stored in a transmission queue. | 02-25-2010 |
| 20100164801 | DEVICE FOR TRACKING POLARIZATION - Provided is a device for tracking polarizations. A receiving polarization tracking device includes a feeder for finding vertical and horizontal vector components by receiving vertical and horizontal polarizations, a polarization estimator for estimating distortion of polarizations using the vertical and horizontal vector components outputted from the feeder, a polarization controller for controlling amplitudes and phases of vertical and horizontal polarizations based on information about the estimated distortion from the polarization estimator and an output signal from the receiving polarization tracking device, and a combiner for combining the vertical and horizontal polarizations controlled from the polarization controller. | 07-01-2010 |
| 20100182924 | METHOD OF CHANGING TRANSMISSION MODE, METHOD OF REQUESTING PACKET RETRANSMISSION, AND METHOD OF RETRANSMITTING PACKET - The present invention is directed to a method of changing a transmission mode, a method of requesting a packet retransmission, and a method of retransmitting a packet with respect to a broadcasting or multicast service. According to the invention, a plurality of terminals provided with one broadcasting or multicast service shares one random access channel (RACH) so as to transmit channel information. Accordingly, a base station receives the channel information through one RACH from the terminal or detects a packet collision generated in the RACH to confirm a request for changing the transmission mode or a request for maintaining the transmission mode by the terminal. | 07-22-2010 |
| 20110041043 | DIVERSITY METHOD USING ERROR CORRECTING CODE - Provided is a diversity method using an error correcting code. The diversity method includes: creating a mother code by start performing error correction coding on an input bit string to be coded; puncturing the created mother code and acquiring an error correcting code including systematic information and partial parity information; and space-time encoding the acquired error correcting code corresponding to each frequency. | 02-17-2011 |
