Abstract: An apparatus and a method of transmitting hierarchically modulated signals are provided. The present invention includes: a basic layer symbol generator generating a first layer signal; an enhancement layer symbol generator generating a second layer signal synchronized with the first layer signal and having different signal power; and a hierarchical modulator hierarchically modulating the first layer signal and the second layer signal, wherein the enhancement layer symbol generator performs constellation rotation rotating bundles configured as constellation points formed by the second layer signal based on constellation points of the first layer signal by a predetermined angle. According to the exemplary embodiment of the present invention, it is possible to improve the receiving performance of the second layer signals by applying the constellation rotation technology to the second layer signals in regards of the signal transmission system using the hierarchical modulation technology.

Abstract: In the present invention, deciding M final soft decision bit values includes a first step of securing an I channel value and a Q channel value of the received transmission signal, a second step of securing initial soft decision bit values for a first bit and a second bit by using the secured I channel value and the secured Q channel value, a third step of cyclically securing initial soft decision bit values for a third bit to an Mth bit by using the initial soft decision bit values for the first bit and the second bit, and a fourth step of securing final soft decision bit values by multiplying the secured initial soft decision bit values by a gain, wherein the gain is calculated based on a reliability adjustment value of the initial soft decision bit values.

Abstract: Provided is a channel estimation apparatus and method using a linear/nonlinear average in a wireless communication system. The present research provides a channel estimation apparatus and method for estimating a channel between a transmitter and a receiver from a pilot-inserted OFDM signal and linearly or nonlinearly averaging the estimating channel, thereby preventing the equalizer performance from being degraded by noise component of the estimated channel and noise amplification caused by deep fading. The channel estimation apparatus includes: a channel estimation unit configured to estimate a channel coefficient of a channel between a transmitter and a receiver from a pilot-inserted carrier signal according to pilot arrangement; and a linear/nonlinear averaging unit configured to linearly or nonlinearly averaging the estimated channel coefficient, thereby preventing an equalizer performance from being degraded by noise component existing in the channel and noise amplification caused by deep fading.

Abstract: A repeater converts a frequency of a received signal based on a local oscillating frequency and transmits a transmitting signal of a frequency that is different from the frequency of the received signal. Here, the local oscillating frequency includes a local oscillating error that may be different in a plurality of repeaters. Accordingly, the repeater cancels the local oscillating frequency error itself in a frequency conversion so that transmitting frequencies between the plurality of repeaters may be identical.

Abstract: A repeater having different input and output frequencies converts a signal received with the input frequency to a first intermediate frequency signal based on a local oscillating frequency for intermediate frequency conversion, and converts the first intermediate frequency signal to a second intermediate frequency signal by performing digital processing on the first intermediate frequency signal. Then, the repeater generates a first frequency tone signal that corresponds to a difference between the input and output frequencies, and generates a second frequency tone signal from the local oscillating frequency for intermediate frequency conversion and the first frequency tone signal. The repeater up-converts the second intermediate frequency signal to the output frequency based on the second frequency tone signal, and transmits the signal.

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: The MAC frame in a wireless communication system includes a terminal ID allocated to each of multiple terminals. At least one connection ID is allocated to each terminal having the terminal ID, and sub-carrier allocation information is allocated to each connection having the connection ID. The sub-carrier allocation information includes a sub-carrier allocation status for each sub-carrier, and the number of allocated information bits for each sub-carrier. The sub-carrier allocation status and the number of allocated information bits for each sub-carrier can be allocated, by sub-carriers, to the sub-carrier allocation information using a same number of bits; or the information on the sub-carrier allocation status is first allocated to the sub-carrier allocation information and the number of allocated information bits for each sub-carrier is allocated.

Abstract: The MAC frame in a wireless communication system includes a terminal ID allocated to each of multiple terminals. At least one connection ID is allocated to each terminal having the terminal ID, and sub-carrier allocation information is allocated to each connection having the connection ID. The sub-carrier allocation information includes a sub-carrier allocation status for each sub-carrier, and the number of allocated information bits for each sub-carrier. The sub-carrier allocation status and the number of allocated information bits for each sub-carrier can be allocated, by sub-carriers, to the sub-carrier allocation information using a same number of bits; or the information on the sub-carrier allocation status is first allocated to the sub-carrier allocation information and the number of allocated information bits for each sub-carrier is allocated.

Abstract: Disclosed are a method and an apparatus for transmitting and receiving broadcast data in a digital broadcasting system. The method for transmitting and receiving broadcast data in a digital broadcasting system includes receiving the main data encoded with symbols having a plurality of levels; deciding whether levels of main data symbols encoded with symbols having the plurality of levels belong to a first group; and mapping the main data symbols to extended levels by using modulation values of the additional data if it is decided that the levels of the main data symbols belong to the first group.

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: In a method of registering with an access point in a terminal of a wireless communication system, a frame includes a downlink sub-frame including a broadcast interval and a first management connection interval, and an uplink sub-frame including an access interval and a second management connection interval, the broadcast interval being used for transmitting a map message, the method includes: sending a first ranging request message to the access point using the access interval; receiving allocation information of a ranging slot from the access point using the map message; performing ranging through the ranging slot; sending a registration request message to the access point using the second management connection interval; and receiving information on whether to permit the registering from the access point using the first management connection interval.

Abstract: The MAC frame in a wireless communication system includes a terminal ID allocated to each of multiple terminals. At least one connection ID is allocated to each terminal having the terminal ID, and sub-carrier allocation information is allocated to each connection having the connection ID. The sub-carrier allocation information includes a sub-carrier allocation status for each sub-carrier, and the number of allocated information bits for each sub-carrier. The sub-carrier allocation status and the number of allocated information bits for each sub-carrier can be allocated, by sub-carriers, to the sub-carrier allocation information using a same number of bits; or the information on the sub-carrier allocation status is first allocated to the sub-carrier allocation information and the number of allocated information bits for each sub-carrier is allocated.

Abstract: A space-time code used for a transmitter to transmit a plurality of data symbols to a receiver in a MIMO system, the space-time code including a code word matrix for transmitting an amount of data symbols corresponding to a product of the number of transmit antennas and a spatial multiplexing rate during one block period, wherein a row index indicates combined signals transmitted through different transmit antennas and a column index indicates time slots that correspond to the number of transmit antennas, and wherein the number of data symbols allocated to each transmit antenna in a code block corresponds to the spatial multiplexing rate, and the data symbols are combined by different combining coefficients for each transmit antenna at every time slot, and simultaneously transmitted through different transmit antennas, and each transmit antenna transmits a different set of data symbols at every time slot.

Abstract: A repeater having different input and output frequencies converts a signal received with the input frequency to a first intermediate frequency signal based on a local oscillating frequency for intermediate frequency conversion, and converts the first intermediate frequency signal to a second intermediate frequency signal by performing digital processing on the first intermediate frequency signal. Then, the repeater generates a first frequency tone signal that corresponds to a difference between the input and output frequencies, and generates a second frequency tone signal from the local oscillating frequency for intermediate frequency conversion and the first frequency tone signal. The repeater up-converts the second intermediate frequency signal to the output frequency based on the second frequency tone signal, and transmits the signal.

Abstract: A repeater converts a frequency of a received signal based on a local oscillating frequency and transmits a transmitting signal of a frequency that is different from the frequency of the received signal. Here, the local oscillating frequency includes a local oscillating error that may be different in a plurality of repeaters. Accordingly, the repeater cancels the local oscillating frequency error itself in a frequency conversion so that transmitting frequencies between the plurality of repeaters may be identical.

Abstract: Disclosed is a method for allocating data and pilots, a transmitting method and device, a receiving method and device in an OFDMA system. A terminal partitions subcarrier groups and symbols from an uplink channel based on a basic pilot pattern generated by a specific reference, receives at least one subchannel based on the partitioned subcarrier groups and symbols, hops the subcarrier groups caused by the subchannel according to hopping patterns, allocates data, and differently positions the pilots per subcarrier group based on the basic pilot pattern. Accordingly, the probability of pilot collision between adjacent cells is reduced, and accuracy of channel estimation is increased through boosting the pilot subcarrier power.

Abstract: In a digital broadcasting signal transmission system, a transmission frame includes a frame body and a frame header, and the frame body is divided into a plurality of sub-bands in the frequency domain and is divided into a plurality of symbols in the time domain. The frame header is provided in the former part of the transmission frame and is transmitted with a signal in the time domain. The frame body includes a plurality of services, and the services respectively receive at least one sub-band and at least one symbol. The frame header includes information on the plurality of services, and information on the plurality of services includes information on the sub-band and the symbol to which the services are allocated, information on channel encoding levels of the services, and information on digital modulation levels of the services.

Abstract: Disclosed is a signal transmission method in a mobile communication system. Unequal error protection (UEP) ratios are determined so that the bits may have different received qualities according to the weights of the bits. The bits are repeated by a bit sequence repeater (210) according to the determined UEP ratios to generate a repeated bit sequence having a predetermined number of bits. The generated repeated bit, sequence is interleaved by an interleaver (220) and the interleaved bit sequence is symbol-mapped by a symbol-mapper (230) to generate a transmission symbol sequence, and the generated transmission symbol sequence is transmitted by the transmitter to a receiver. Furthermore, also a corresponding signal reception method, a corresponding signal transmitter and a corresponding signal receiver are disclosed.

Abstract: The present invention relates to a transmission method, a transmission apparatus, a reception method, and a reception apparatus of a digital broadcasting signal that can add frame header information to a front portion of a transmission frame in a transmission system for digital broadcasting to thereby determine a different transmission mode, modulation level, hierarchical modulation, error correction code, and the like for each temporally different transmission frame, and a transmission frame structure thereof. The transmission frame structure includes a frame header containing multiplexing information of the transmission frame, and a frame body containing data information associated with a service provided by the transmission frame.

Abstract: An apparatus for estimating a RSSI of a signal transmitted/received in a wireless network, the apparatus including an ADC quantizing one of I-branch and Q-branch signals, extracted from the signal, into a digital signal; an absolute value calculating unit calculating an absolute value of the digital signal quantized by the ADC and outputting a result; an accumulate unit accumulating an output of the absolute calculating unit for a given time period and outputting a result; a square unit squaring an output of the accumulate unit and outputting a result; and a multiply unit multiplying an output of the square unit by a given value and outputting a result, the given value being determined based on the number of input bits, an input clip level, and input resistance of the ADC when the probability density functions at input and output signals of the ADC are approximately Gaussian with zero mean.