Abstract: An apparatus for multi-path search using a dual code generator includes: first and second code generators for generating first and second search codes, changing phases, and generating a search-done interrupt; a multi-path search engine for receiving the search codes from the code generators and performing a search process for detection of the multiple paths; a search controller for controlling the code generators to generate the search codes, and sending the search-done interrupt from the code generators; and a drive controller for generating a slewing command to the search paths and a search command, sending the commands to the search controller, reading search results from the search controller upon generation of the search-done interrupt, and generating second slewing and search commands for a new search process.

Abstract: Disclosed is an adaptive transmit and receive method and device in a multiple-antenna wireless communication system. A transmit mode comprises different main transmit modes each of which includes one or both of a sub-transmit mode based on STBC and a sub-transmit mode based on SM. A receiver calculates an STBC performance parameter and a SM performance parameter, and a transmitter uses the parameters to determine a main transmit mode with maximum data rates and select a sub-transmit mode for minimizing power consumption. The transmitter channel-encodes, modulates and antenna-maps input data according to the selected transmit mode, and outputs results to the receiver. The receiver antenna/symbol-demodulates and channel-decodes the received data.

Abstract: Disclosed is a frequency hopping method in an OFDM system, comprising: (a) detecting a mutual interference degree between different cells, and determining whether to use different frequency hopping patterns between the cells for interference averaging according to the mutual interference degree interference degree; (b) determining a number P of the different frequency hopping patterns needed between all the cells in the system; (c) generating the frequency hopping patterns of more than the number P and allocating the generated frequency hopping patterns to each cell, the frequency hopping patterns having the same frequency collision times between two channels in the different frequency hopping patterns; and (d) frequency-hopping the channels in each cell according to the allocated frequency hopping pattern.

Abstract: An RM code soft decision decoding method using decision by majority comprises: (a) performing multiplication on a bit group of a codeword, and calculating an information bit's estimate group; (b) summating elements of the group and obtaining a final estimate of the degree's information bit to perform decision by majority; (c) using the final estimate to generate a codeword corresponding to each degree's information bit final estimate, and removing the generated codeword from the codeword of (a); (d) repeating the step (c) for the final estimates of the remaining degrees' information bits other than zero-order information bit; and (e) summating elements of codewords of results performed on the final estimates of the first-order information bit in (d) to estimate the zero-order information bit's final estimate.

Abstract: Disclosed are an adaptive pilot symbol assignment method that flexibly controls the number of transmit antennas according to each user's moving speed, channel status, or user request, and assigns proper pilot symbols in the downlink of an OFDMA (Orthogonal Frequency Division Multiplexing Access) based cellular system; and a sub-carrier allocation method for high-speed mobile that allocates some sub-carriers to assign proper pilot symbols for ultrahigh-speed mobile users, and the rest of the sub-carriers to the other users to assign proper pilot symbols to the users, on the assumption that the ultrahigh-speed mobile users have a traffic volume almost insignificant to the whole traffic volume.

Abstract: In an OFDMA-based cellular system, a frame of a downlink signal includes a common slot and traffic slots. The common slot includes a synchronization preamble and a cell search preamble. The synchronization preamble has a structure for synchronizing time and frequency, and the cell search preamble has a cell search structure. The traffic slot includes pilot symbols provided on the time and frequency axes. A cyclic prefix is used to estimate initial symbol synchronization, and the initial symbol synchronization and the synchronization preamble are used to synchronize the frame. The synchronization frame and the cell search preamble are used to estimate time and frequency synchronization. The cell search preamble is used to search cells. When the initial synchronization is performed, the cyclic prefix is used to track the frequency, the synchronization preamble is used to track symbol synchronization, and the cell search preamble is used to track fine frequency synchronization.

Abstract: This invention relates to a method and apparatus for increasing the performance of searcher by using the array antenna when the signal to interference plus noise ratio is low. The two-dimensional searcher performs the spatial-filtering to reduce the noise and interference components and then correlates the spatial-filtered signal with a pseudo noise (PN) code to thereby detect the incoming signals and acquire the corresponding code timings. Furthermore, the two-dimensional searcher can be used to increase the performance of a finger beamformer in two ways. One is to use searcher beamforming weight as initial finger beamforming weight to increase the convergence speed in the adaptive beamforming algorithms. The other is to reduce an amount of computation in the angle of arrival estimation algorithms by calculating the azimuth power spectrum only for the specific angle range.

Abstract: Method for providing frequency-hopping OFDMA using symbols of comb patter, the method including the steps of: a) assigning frequency domain signal X(k) of comb pattern (comb symbol, k is frequency index) to modulated data sequence, the comb symbol comprising predetermined number of sub carriers (sub carrier group) which are placed with predetermined interval in the whole available frequency band; b) getting the comb symbol hopped for the comb symbol to have independent frequency offset; and c) inverse fast fourier transforming the comb symbol to time domain signal x(n) (n is time index) and transmitting the signal.

Abstract: Disclosed is a receiver digital filter for a digital IF signal processor suitable for the specification of each communication standard in a communication system that supports at least one communication standard. The filter for each standard is constructed as one block, and includes a block for externally implementing the constructed block. The coefficient of the digital filter constructed in one block is implemented with an external input or an internal filter coefficient calculator by a basic filter building block. In this manner, the common resources required in the digital filter used in each communication standard are shared, and only the additionally required resources are selectively implemented. Since the shared resources are calculated by dynamic programming, a considerably smaller number of additional resources are required.

Abstract: Disclosed is an adaptive transmit and receive method and device in a multiple-antenna wireless communication system. A transmit mode comprises different main transmit modes each of which includes one or both of a sub-transmit mode based on STBC and a sub-transmit mode based on SM. A receiver calculates an STBC performance parameter and a SM performance parameter, and a transmitter uses the parameters to determine a main transmit mode with maximum data rates and select a sub-transmit mode for minimizing power consumption. The transmitter channel-encodes, modulates and antenna-maps input data according to the selected transmit mode, and outputs results to the receiver. The receiver antenna/symbol-demodulates and channel-decodes the received data.

Abstract: Disclosed is an implementation method for simplifying a complicated message-passing function in a decoder for decoding block codes encoded with low-density parity-check (LDPC) codes and only using a summator and a shifter to simplify the hardware structure of the decoder, in which method the input interval of the message-passing function for binary representation of a message input is divided and the respective divided intervals are linearized to allow the calculation of the output of the message-passing function without using a memory. Based on the fact that the message-passing function is similar in structure to an exponential function, the linearized intervals are set to make the maximum value expressible in each digit of the binary representation as the boundary of the intervals.

Abstract: Disclosed is a hybrid multi-user interference cancellation method for canceling interference between a plurality of user signals, which comprises: receiving a plurality of external user signals, calculating powers of the user signals, and numbering the calculated signal powers in their intensity orders; sorting the user numbers in descending order; forming at least one user cluster so that the signal powers following the sorted user numbers may differ less from a central value or a mean value in the same cluster; and performing parallel interference cancellation on the respective user signals within the same cluster, and performing successive interference cancellation between the formed clusters.

Abstract: Disclosed is a transmitting and receiving method for reducing a time-varying channel distortion in an orthogonal frequency division multiplex (OFDM) system. In the present invention, the transmitter defines M sub-channels in one data group, mathematically analyzes a change of channel for each path causing a time-varying channel distortion in a high-speed mobile environment by approximation, calculates a weight value based on the mathematical analysis and assigns the calculated weight value to transmit data of each sub-channel. Subsequently, the receiver combines the signals of these M sub-channels and demodulates the combined signals. Accordingly, the present invention greatly reduces a distortion caused by the time-varying channel to improve a bit error rate and a channel estimation performance.

Abstract: An RM code soft decision decoding method using decision by majority comprises: (a) performing multiplication on a bit group of a codeword, and calculating an information bit's estimate group; (b) summating elements of the group and obtaining a final estimate of the degree's information bit to perform decision by majority; (c) using the final estimate to generate a codeword corresponding to each degree's information bit final estimate, and removing the generated codeword from the codeword of (a); (d) repeating the step (c) for the final estimates of the remaining degrees' information bits other than zero-order information bit; and (e) summating elements of codewords of results performed on the final estimates of the first-order information bit in (d) to estimate the zero-order information bit's final estimate.

Abstract: A sectored antenna system to optimize the distance between adjacent sensors of an array antenna in a CDMA mobile communication system in which success rate of softer handoff and antenna gain is increased and power consumption of terminals may be evenly distributed. In the CDMA mobile communication system, a cell is divided into a number of sectors. A sector antenna system comprising a number of linear array antennas, in which distance between the antenna sensors is determined in consideration of overlapping angle of beams to supply softer handoff is provided. The system also includes carrier demodulators, matched filters, a weight vector estimator, weight vector multipliers, weight vector combiners, parallel demodulators, and a signal combiner.

Abstract: An apparatus for multi-path search using a dual code generator includes: first and second code generators for generating first and second search codes, changing phases, and generating a search-done interrupt; a multi-path search engine for receiving the search codes from the code generators and performing a search process for detection of the multiple paths; a search controller for controlling the code generators to generate the search codes, and sending the search-done interrupt from the code generators; and a drive controller for generating a slewing command to the search paths and a search command, sending the commands to the search controller, reading search results from the search controller upon generation of the search-done interrupt, and generating second slewing and search commands for a new search process.

Abstract: This invention relates to a method and apparatus for increasing the performance of searcher by using the array antenna when the signal to interference plus noise ratio is low. The two-dimensional searcher performs the spatial-filtering to reduce the noise and interference components and then correlates the spatial-filtered signal with a pseudo noise (PN) code to thereby detect the incoming signals and acquire the corresponding code timings. Furthermore, the two-dimensional searcher can be used to increase the performance of a finger beamformer in two ways. One is to use searcher beamforming weight as initial finger beamforming weight to increase the convergence speed in the adaptive beamforming algorithms. The other is to reduce an amount of computation in the angle of arrival estimation algorithms by calculating the azimuth power spectrum only for the specific angle range.

Abstract: The present invention relates to structures of the spread CDMA system of band diffusion with antenna array. The present invention, structures of 2-D demodulator are provided, for spread spectrum CDMA systems with antenna array which can increase coverage area of base station and system capacity, by extracting and combining all information needed in time and space domains, using only the information which shall be calculated in a CDMA system inherently.

Abstract: In the hardware-efficient demodulator for a CDMA adaptive antenna array mechanism of a mobile radio communication system, a correlators bank receives digital baseband signals received through an antenna array of a base station and computes correlation values with a local code sequence. A beamformer receives the digital baseband signals and the correlation values from the correlators bank and calculates beamforming weight vectors. A searchers bank receives the digital baseband signals and calculates an initial acquisition and reliable timing information for a multipath search by a common work with the beamformer, which uses a beamforming algorithm. A beamforming complex multiplier for a finger performs a complex multiplication for the beamforming weight vectors and the digital baseband signals, and sums up them.

Abstract: In the hardware-efficient demodulator for a CDMA adaptive antenna array mechanism of a mobile radio communication system, a correlators bank receives digital baseband signals received through an antenna array of a base station and computes correlation values with a local code sequence. A beamformer receives the digital baseband signals and the correlation values from the correlators bank and calculates beamforming weight vectors. A searchers bank receives the digital baseband signals and calculates an initial acquisition and reliable timing information for a multipath search by a common work with the beamformer, which uses a beamforming algorithm. A beamforming complex multiplier for a finger performs a complex multiplication for the beamforming weight vectors and the digital baseband signals, and sums up them.