Abstract: Improved methods and apparatuses are provided to address a potential “hidden beam problem” in wireless communication systems employing smart antennas. The improved methods and apparatuses utilize complementary beamforming (CBF) techniques, such as, for example, Subspace Complementary Beamforming (SCBF), Complementary Superposition Beamforming (CSBF) and/or Single Beam Complementary Beamforming (SBCBF) techniques.

Abstract: Improved methods and apparatuses are provided to address a potential “hidden beam problem” in wireless communication systems employing smart antennas. The improved methods and apparatuses utilize complementary beamforming (CBF) techniques, such as, for example, Subspace Complementary Beamforming (SCBF), Complementary Superposition Beamforming (CSBF) and/or Single Beam Complementary Beamforming (SBCBF) techniques.

Abstract: A method of performing receive antenna selection is presented. The method executes a determination operation for a set of receive antennas, determines a maximum result of the determination operation for two of the antennas, eliminates one of the two antennas from the set of antennas, and repeats the determination and elimination process until only a predetermined number of antennas remain in the set. The signals from these remaining antennas are then processed. The present invention reduces receiver complexity and cost.

Abstract: Improved methods and apparatuses are provided to address a potential “hidden beam problem” in wireless communication systems employing smart antennas. The improved methods and apparatuses utilize complementary beamforming (CBF) techniques, such as, for example, Subspace Complementary Beamforming (SCBF), Complementary Superposition Beamforming (CSBF) and/or Single Beam Complementary Beamforming (SBCBF) techniques.

Abstract: In an implementation of directed wireless communication, a multi-beam directed signal system coordinates directed wireless communication with client devices. A transmit beam-forming network routes data communication transmissions to the client devices via directed communication beams that are emanated from an antenna assembly, and a receive beam-forming network receives data communication receptions from the client devices via the directed communication beams.

Abstract: A full digital symbol timing recovery apparatus which can recover a symbol timing from a received signal. In the apparatus, a fixed oscillator generates a frequency signal having a constant frequency. An analog-to-digital converter samples the received signal at the constant frequency supplied from the fixed oscillator and converts the analog signal into a digital signal. A matching matches and filters the digitized signal according to a load filter coefficient and adjusts a timing phase. A timing error detector detects a symbol timing error from the output of the matching filter. A subtracter subtracts a predetermined value from the output of the timing error detector and outputs the subtracted result. A numerically controlled oscillator generates a frequency signal which varies periodically according to the output of the subtracter.

Abstract: A carrier recovery apparatus includes a loop filter that converges quickly and corrects a large frequency error. The carrier recovery apparatus includes a multiplier, a matched filter, a phase error detector, a loop filter and a numerically controlled oscillator (NCO). A bandwidth varying circuit varies the bandwidth of the loop filter according to whether the signal output from the matched filter is phase-locked. A frequency error detector detects a frequency error from the output of the matched filter. An adder adds each level of an input sweep signal and the output of the loop filter, and supplies the added results to the NCO. A switch selectively supplies the output of the loop filter to the adder. A controller generates a sweep signal having a plurality of levels and controls turning the switch on and off.

Abstract: An automatic frequency control apparatus includes a sampling portion for sampling the signal transmitted according to a phase-shift keying method, a phase difference detector for detecting the phase difference between the currently sampled signal and the immediately preceding sampled signal, and a phase bin comparator for determining which of a number of reference phases the phase of the transmitted signal is closest to, using a quantization characteristic of phase during transmission. The frequency offset generated by the distance between the frequency of a carrier wave and the local oscillation frequency of a receiver, or by the Doppler shift, in a MPSK communication method is determined as the phase difference between the detected phase difference information and the determined reference phase information. The apparatus can be used for the automatic frequency control of a modem using any type of MPSK modulation.

Abstract: An automatic frequency control apparatus used in an MPSK communication system detects a frequency offset between a carrier and a local oscillation signal for adjustment of a local oscillation frequency. A phase difference detector generates a first phase difference detection signal having, as a phase value, a difference between the phases of various samples of the sampled signal. A phase altering unit generates a second phase difference detection signal having a phase value different from that of the first phase difference detection signal. A frequency offset signal generator estimates transmission phase information by using the phase value of the second phase difference detection signal and reference phase signals used for MPSK modulation, thereby generating a frequency offset signal which is determined by the transmission phase signal and the second phase difference detection signal.

Abstract: A method for adaptively turning on or off a decision directed algorithm (DDA) is performed according to the convergence state of the data to be equalized in a blind equalization system for use in a digital communication receiver. Each quadrant of a two-dimensional plane having an I-axis and Q-axis is divided into two decision areas. Then, a sign pair of actual error estimation data is calculated with respect to each area. If the decision error of the received symbol data is calculated, it is determined whether the sign of the decision error coincides with that of the actual error estimation data. The DDA is performed with respect to the symbol data of which the sign coincides with each other to update the equalization coefficient. The method further reduces the number of decision areas for dividing the plane formed by the I-axis and Q-axis in which the symbol data is arranged, to permit faster convergence speed and to further suppress the ratio of the symbol error.

Abstract: An adaptive equalizing system equalizes an unequalized signal and performs carrier recovery for use in a digital communication receiver. An equalizing coefficient is initialized by a constant modulus algorithm (CMA) and the initialized equalizing coefficient is more finely updated by a stop-and-go algorithm (SGA). When the convergency by the CMA reaches a predetermined threshold value, carrier recovery is performed, while when an average value of the phase error during performing the carrier recovery is less than another predetermined threshold value, the equalizing algorithm is converted into the SGA. Thus, the adaptive equalizing apparatus can equalize the received signal more simply and reliably.

Abstract: A method for controlling algorithm conversion between the Godard algorithm and the decision-directed algorithm (DDA) is used in a blind equalization system for a digital communication receiver. The step size is varied while repeatedly performing the Godard algorithm. If a distance average value is smaller than a predetermined threshold value, the algorithm is converted into the DDA to calculate the equalization coefficient. If the distance average value is larger than another predetermined threshold value, the algorithm is converted into the Godard algorithm. Thus, the conversion between the Godard algorithm and the DDA and the step size alteration are adaptively performed according to a degree of convergency of the received signal, to obtain more quick and better equalization.