Abstract: The present invention relates to a method for timing acquisition and carrier frequency offset estimation of an OFDM communication system and an apparatus using the same. For this purpose the present invention provides a method for calculating at least one auto-correlation and calculating an observation value by performing a sliding sum on the at least one auto-correlation, and calculating a peak point of an absolute value of the observation as frame timing. In addition, the present invention provides a method for generating a third OFDM symbol that is generated by delaying a second OFDM symbol, calculating an observation value through the second and third OFDM symbols, and calculating a phase difference from a result of multiplication of the observation value and a conjugate complex value of the observation value such that a carrier frequency offset can be estimated.

Abstract: Provided is a pulse shaping method. A time interval is predefined so as to shape a pulse used for a transmit pulse and a receive filter response, a parameter is generated by using a weight coefficient and a plurality of cosine functions that are multiplied and added to be output during the predetermined time interval, and 0 is output during another interval, thereby shaping the pulse. The weight coefficient is updated by using the normalized MSE so as to shape the pulse to be optimized for the predetermined time interval.

Abstract: A mobile station and a base station communicate with each other using a frame including one or more downlink subframes and one or more uplink subframes. The base station begins the transmission of a data burst in a subframe corresponding to a downlink subframe index. The mobile station transmits feedback for the data burst to the base station in a subframe corresponding to an uplink subframe index. If the frame uses a time division duplex scheme, the uplink subframe index is determined by at least using the downlink subframe index and the parameter value.

Abstract: The present invention relates to a method of forming a random beam, and a beam forming apparatus. A quantization preprocessor and a random unitary matrix having a predetermined pattern are used to form a beam on a mobile terminal. A base station forms a beam using a codeword index of a quantization codebook received from a mobile terminal and channel quality information corresponding to the codeword index, and the mobile terminal generates the codeword index and the channel quality information using pilot signals generated by the base station. The number of pilot signals is equal to the number of transmitting antennas. Therefore, a codebook that has been known to both the mobile terminal and the base station is used, and the mobile terminal can select the codeword index for quantization, which makes it possible to selectively give diversity and thus improve the system efficiency.

Abstract: A method of transmitting data from a terminal in a cellular system is provided. The data transmission method includes: calculating the transmission capacity of a predetermined number of vectors among pairs of orthogonal vectors; selecting the vector having the largest transmission capacity as a reference vector among the predetermined number of vectors; and transmitting data to a base station using the reference vector.

Abstract: Disclosed are a method and apparatus of adaptive transmission signal detection based on a signal-to-noise ratio and a Chi-squared distribution for decoding a reception signal in the form of multi-streams into a transmission signal, the method comprising: receiving a reception signal vector; estimating a channel matrix of a channel that the reception signal vector experienced; performing QR decomposition based on the estimated channel matrix; calculating dimensions of divisional spaces adaptively on the basis of a signal-to-noise ratio (SNR) or a signal-to-interference noise ratio (SINR); detecting a maximum likelihood point having a maximum likelihood value among lattice points within each divisional space optained on the basis of results from performing the QR decomposition and calculating dimension of the divisional spaces; and recovering a transmission signal vector based on the detected maximum likelihood points.

Abstract: In a mobile wireless network system including a plurality of nodes, available resources of a transmitting node and available resources of a receiving node are searched for. Commonly overlapped allocatable resources among available resources of a transmitting node and available resources of a receiving node are searched for, areas corresponding to the calculated allocation resource number according to an allocation condition that is set in the allocatable resource area are selected, and the areas are allocated to the transmitting node or the receiving node.

Abstract: A method for routing and setting up a connection to provide Quality of Service (QoS) required in a wireless network is provided, which allows to use a path capable of providing QoS higher than a certain level between a source node and a destination node. A routing apparatus includes: a connection management unit that receives a connection setup request directed to a destination node, determines a predicted path leading to the destination node and the next node, and transmits a connection setup request to the next node; a resource allocation unit that allocates resources so as to satisfy required QoS; a routing unit that measures available QoS information of a link and enables the exchange of information of the link including the QoS information with the nodes of the network; and a routing information management unit that stores received routing information.

Abstract: In a mobile wireless network system including a plurality of nodes communicating with each other, a node attempting to transmit data finds useable resources through performing carrier sensing on packet data unit (PDU) slots and transmits data through the found resources. A node attempting to receive data finds useable resource through performing carrier sensing on acknowledge (ACK) slots and receives data through the found resources.

Abstract: When an event associated with a mobile station occurs, a relay station requests a base station to allocate a dedicated control channel required for transmitting control information on the mobile station to the base station. Next, when the control information on the mobile station is generated, the relay station transmits the control information to the base station through the dedicated control channel. Accordingly, since the base station allocates the dedicated control channel to the relay station in advance before the control information is generated in the relay station, the relay station can transmit the control information to the base station with a minimum of time delay.

Abstract: In an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network, a communication node receives information regarding a next transmission time of a 1-hop node and a 2-top node through the 1-hop node, calculates next transmission intervals of the 1-hop node and the 2-hop node, determines a next transmission time of the communication node by using the next transmission intervals of the 1-hop node and the 2-hop node, and then transmits, to an 1-hop node of the communication node, the information of the next transmission time together with the information of the transmission time of the 1-hop node, received from the 1-hop node.

Abstract: The present invention relates to a precoder and a precoding method in a multi-user multi-antenna communication System. When a transmission part (100) having a plurality of antennas transmits a plurality of signals to a receiving part (200) having an antenna, the precoder and the precoding method using the same prevents System performance degradation caused by interference signals and efficiently reduces transmission power while changing the constellation rotary angle. When the power is controlled by using the precoder, the System performance is enhanced while not damaging the structural gain of the existing multi-user multi-antenna precoder.

Abstract: Disclosed is a binary signal modulator for minimizing deterioration of receiving performance caused by phase error. The binary signal modulator receives binary signals, and converts the binary signals into complex symbols according to a predetermined mapping relation. Here, the mapping relation is generated when a plurality of mapping symbols are arranged on a plurality of trajectories so that the distance between the mapping symbols is greater than or equal to a predetermined distance and the phase between the mapping symbols is greater than or equal to a predetermined angle from among the trajectories starting from a plurality of points on the complex plane, and a distance between the trajectories is greater than or equal to the minimum distance from among the distances between the points.

Abstract: A space domain filter detecting method in a multi-antennas wireless communication system, which processes time and space domain interference differently. The space domain filter detecting method comprises the following steps: firstly, the received signals are matched-combined in time domain and space domain; secondly, using the combined signals as an observation value, the space domain filtering is performed; thirdly, an estimated value is subtracted from the filtered signals, and the result is taken as a detection output, which is sent to a determiner in a non-error control coding system to get a hard determination output or is sent to a determiner in an error control coding system to get a soft determination output that is finally sent to a coder. The method promotes the transmission rate and the anti-interference ability and advances the spectrum efficiency.

Abstract: Respective codewords of quantization codebooks corresponding to a number of data streams are selected based on channel information estimated by a received training symbol. A stream mode is selected among stream modes to determine a modulation method applied to each data stream. The data stream is detected by using the codeword corresponding to the quantization codebook of the data stream corresponding to the selected stream mode as a precode matrix, and the detected data stream is modulated. In this case, a receiving apparatus performs a feedback operation so that indexes of the selected stream mode and the codeword used as the precode matrix may be transmitted to the transmitting apparatus. The transmitting apparatus selects the number of transmitted data streams and the modulation method based on the transmitted index of feedback streams by the feedback operation.

Abstract: The present invention relates to a multi-input multi-output (MIMO) system for enhancing transmission performance. The MIMO system uses space-time encoding and transmit antenna selection methods, and includes a transmitter (100) and a receiver (200). The transmitter (100) includes N transmit antennas (130-1, 130-4) that are more than M transmit antennas (130-1, 130-3) used for transmitting a signal to space channel, selects the M transmit antennas (130-1, 130-3) among the N transmit antennas (130-3 130-4), and transmits symbol by space-time encoding the symbol. The receiver (200) includes M receive antenna (120-1, 210-2) for receiving a signal from the space channel, detects an information symbol by using the signal received through the receive antenna (210-1, 210-2), generates transmit antenna selection information for selecting M transmit antennas (130-1, 130-3) among transmit antennas (i30-1, . . . 7130-4) with reference to a channel estimate, and returns the information to the transmitter.

Abstract: A method and apparatus for distributed scheduling within an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network may be provided. A requester and a granter in the wireless mesh network may perform three way-handshaking using distributed scheduling messages. A plurality of distributed scheduling messages may use different sub-channels. The request may reserve sub-channels to be used by respective scheduling messages.

Abstract: A sphere decoder sets a Euclidean distance between a lattice vector obtained by using an MMSE or ZF estimate and a received signal as an initial radius, further reduces the initial radius, and searches lattices points included inside a hypersphere with the further reduced initial radius. In addition, one lattice vector having a minimum Euclidean distance is output. One dimension is selected to reduce an initial radius, and estimates in other dimensions are kept fixed, excluding the selected dimension. Then candidate lattice points are searched in the selected dimension, excluding a current estimate, such that a minimum Euclidean distance and a lattice point estimate corresponding to the minimum Euclidean distance are obtained. The initial radius is updated by the minimum Euclidean distance, and a final lattice vector is constructed by combining a lattice point estimate corresponding to the initial radius and the lattice point estimates in other dimensions.

Abstract: A receiver according to an exemplary embodiment of the present invention receives a transmitted signal, converts the signal to a predetermined symbol, and estimates channel information including a channel gain of a channel of the transmitted signal. In addition, the receiver generates an intermediate processing value for decoding the signal based on the estimated channel information and the symbol, and normalizes the intermediate processing value to the channel gain to generate a reference value. The generated reference value is used for a soft-decision value for decoding the signal. In addition, when the signal is decoded by using a hard-decision value, a constellation point value that is closest to the reference values is generated and set as the hard-decision value.

Abstract: A detection method of space domain maximum posteriori probability (MAP) in a wireless communication system is a kind of detection technique of space domain MAP in a multi-aerial wireless communication system, which makes the detection of iteration soft interference elimination for the interference signals in the other moments, and makes the MAP detection or the simplified MAP detection for the all signals in current time and space domain. It includes the steps of: taking a fading block as a unit; the received signals are matched and combined in time domain and space domain, and calculating an equivalent channel matrix; making the sequence detection, calculating estimation and variance of the signals before the ending of detecting internal iteration; when the internal iteration detection finishes, the result is outputted, or is outputted after hard decision.