Abstract: In a communications device having a physical layer device and a processing device connected to the physical layer device, the number of input/output (I/O) ports required for communication between the devices in the gigabit range is substantially reduced by utilizing millivolt differential I/O drivers and receivers. In addition, a calibration feedback loop synchronizes the data and clock signals on the processing device, thereby eliminating the need to recover the clock on the processing device.

Abstract: A base station having the strongest downlink signal is identified by utilizing a unique slope of a pilot tone hopping sequence being transmitted by a base station. Specifically, base station identification is realized by determining the slope of the strongest received pilot signal, i.e., the received pilot signal having the maximum energy. In an embodiment of the invention, the pilot tone hopping sequence is based on a Latin Squares sequence. With a Latin Squares based pilot tone hopping sequence, all a mobile user unit needs is to locate the frequency of the pilot tones at one time because the pilot tone locations at subsequent times can be determined from the slope of the Latin Squares pilot tone hopping sequence. The slope and initial frequency shift of the pilot tone hopping sequence with the strongest received power is determined by employing a unique maximum energy detector.

Abstract: Disclosed is a channel estimator adopting masking. In a channel estimator using a CIR (channel impulse response) estimating value, the present invention includes a CIR masking unit removing a noise included in the CIR estimating value. Accordingly, the present invention is capable of filtering noises resulting from finiteness of the PN sequence used in finding the cross correlator, thereby enabling to enhance accuracy for the CIR estimating value. And, the enhanced accuracy for the CIR estimating value enables to improve tracking performance to the time variable channel of the frequency domain equalizer using the channel estimator.

Abstract: A wireless device and system employs a two-dimensional (2-D) Trellis code that can be applied to Quadrature Phase Shift Keying (QPSK) and higher order Quadrature Amplitude Modulation (QAM) constellations. The Trellis codes employed have optimal Euclidean distance properties for QPSK constellations, and have very good Euclidean distance properties for higher-order QAM constellations. The Trellis codes are suited for transmission systems that adopt multi-mode QPSK and QAM constellations with different data rates since the same Trellis code can be applied to all modulation formats and the same decoder can be used at the receiver for all modulation formats. Modulation formats include QPSK, 8-QAM, 16-QAM, 32-QAM, and 64-QAM and may be extended to even higher order modulations formats.

Abstract: Base station identification and downlink synchronization are realized by employing pilots including known symbols transmitted at prescribed frequency tones in individual ones of prescribed time intervals. Specifically, the symbols used in the pilots are uniquely located in a time-frequency grid, where the locations are specified by periodic pilot tone hopping sequences. In a specific embodiment of the invention, a period of a pilot tone hopping sequence is constructed by starting with a Latin-square based hopping sequence, truncating it over time, and possibly offsetting and permuting it over frequency. Particular examples of pilot tone hopping sequences are parallel slope hopping sequences in which the periodicity of the sequences is chosen to be a prime number of symbol time intervals. In another embodiment of the invention, a notion of phantom pilots is employed to facilitate use of various system parameters while accommodating the above noted pilot tone hopping sequences.

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: A method, apparatus, article of manufacture, and a memory structure for transcieving data and a clock on a single data stream. The method comprises the steps of receiving an encoded data stream, the encoded data stream generated by encoding a data stream by a duty factor representing a value of the data in the data stream; and decoding the encoded data stream according to the duty factor of the encoded data stream. The apparatus comprises a receiver for receiving an encoded data stream, the encoded data stream generated by encoding a data stream by a duty factor representing a value of the data in the data stream; and a decoder, communicatively coupled to the receiver, the decoder for decoding the encoded data stream according to the duty factor of the encoded data stream.

Abstract: Disclosed is a smart antenna system and method. The present invention uses a gradient value closer to a true gradient in weight estimation using the correlation matrix having both of the Hermitian and Toeplitz properties, thereby shortening a convergence speed of the algorithm of estimating the weight.

Abstract: A method and apparatus for recognizing signals in a mobile communication system reduces a mean acquisition time based on a signal-to-noise ratio of a received signal and the moving speed of user equipment which transmitted the signal. This apparatus includes a multi-path searcher of a base station modem which analyzes a signal from the moving user equipment using a Doppler estimator, decides the moving speed of the user equipment, and transmits a control signal proportional to the moving speed to coherent and non-coherent accumulators. A signal-to-interference ratio estimator then decides a signal-to-noise ratio of the signal and compensates for a control signal transmitted to each accumulator. Through this approach, higher reliability is achieved than other multi-path searchers, which merely consider the moving speed of the user equipment. Also, a mean acquisition time taken to recognize and search signals and an initial synchronization time are reduced and wireless resources of a base station are saved.

Abstract: A transmitter may transmit using OFDM-MIMO or OFDM-SDMA depending on channel characteristics.

Abstract: An apparatus and method for communication using sound waves is disclosed. More particularly, orthogonal frequency division multiplexing scheme is used to transmit and receive digital data on sound waves. In one embodiment, the sound waves are used to exchange information. In another aspect, the sound waves are used to authenticate an individual or device.

Abstract: From potential symbol combinations transmitted from a transmitter, Euclidean distances between the received signals and the symbol vectors are determined in light of the corresponding channel responses and stored in a Euclidean distance table, from which the smallest Euclidean distance is selected as a hard decision. The hard decision is used to find a bit vector corresponding to the estimated symbol vector associated with the hard decision. For each bit in the bit vector, a reduced Euclidean distance table is created to include only Euclidean distances associated with a competing bit associated with the hard decision. The minimum Euclidean distance from each reduced Euclidean distance table becomes a soft demapping decision for a corresponding bit. Log likelihood ratios for each bit are determined by the difference between the hard decision and respective soft demapping decisions. The differences are provided to a channel decoder to recover the originally transmitted bits.

Abstract: A delay compensation circuit for a delay locked loop which includes a main delay line having a fine delay line comprising fine delay elements and a coarse delay line comprising coarse delay elements, the main delay line being controlled by a controller, the delay compensation circuit comprising: an adjustable fine delay for modeling a coarse delay element, a counter for controlling the adjustable fine delay to a value which is substantially the same as that of a coarse delay element, a circuit for applying a representation of the system clock to the delay compensation circuit, and a circuit for applying the fine delay count from the counter to the controller for adjusting the fine delay line of the main delay line to a value which is substantially the same as that of a coarse delay element of the main delay line.

Abstract: In a secure method of deciding on a communication channel in a data decompression device, the compressor detects channels that vary from one frame to another, which are referred to as “active” channels. It transmits active and passive channels in a data block which also contains a state code locating the active data in the starting frame in order to be able to reconstitute it in the decompressor. A reference pattern is transmitted incorporating the passive channels and a majority vote statistical analysis is applied to the states of the passive channels to decide on the state (0 or 1) of each bit constituting the pattern repeated by each passive channel. One particular application of the method is to a satellite telecommunication system.

Abstract: A method and system for adaptive prefiltering of a signal for transmission is described. The method includes determining a reference starting value of coefficients for a receiver equalizer filter, receiving an indication of a change in channel characteristics based on a signal received at the receiver equalizer filter, computing coefficients for an adaptive filter based on the reference starting value and the change in channel characteristics, setting the coefficients of the adaptive filter equal to the computed coefficients, and filtering a signal for transmission through the adaptive filter.

Abstract: System and method for analyzing communication signals. A digital signal comprising multiple samples is received, representing a plurality of binary symbols. Zero crossings of the signal are determined, each comprising a respective first sample immediately preceding the zero crossing and a respective second sample immediately following the zero crossing. Per zero crossing, an error expression is determined interpolating between the first and second samples as a function of estimated period T and estimated offset ? of the signal. Based on the error expressions, values of T and ? are determined using a linear fit that minimizes a total error of values of the error expressions. T and ? are usable in analyzing the signal, e.g., each zero crossing corresponds to a respective symbol represented by a respective segment of the signal. The segments are overlaid based on T and ?, forming an eye diagram usable to analyze the signal.

Abstract: A nonlinear distortion compensating circuit in which a digital value expressing the amplitude of an input signal is divided into upper and lower bits. Only the upper bits are input to a first memory address. A value obtained by adding 1 to the upper bits is input to a second memory address, or, an interpolation circuit to which the upper bits are input, inputs the upper bits to a first memory storing data corresponding to an even numbered address and a second memory storing data corresponding to an odd numbered address, and performs interpolation by adding outputs from the memories by weighting these outputs in accordance with a value expressed by the lower bits. The input signal is multiplied by the obtained value. An interpolation circuit output is an orthogonal coordinate expression (combination of a real part and imaginary part) or polar coordinate expression (combination of an amplitude and phase).

Abstract: A programmable logic device (“PLD”) is augmented with programmable clock data recover (“CDR”) circuitry to allow the PLD to communicate via any of a large number of CDR signaling protocols. The CDR circuitry may be integrated with the PLD, or it may be wholly or partly on a separate integrated circuit. The circuitry may be capable of CDR input, CDR output, or both. The CDR capability may be provided in combination with other non-CDR signaling capability such as non-CDR low voltage differential signaling (“LVDS”). The circuitry may be part of a larger system.

Abstract: A digital signal processor performs despread decoding in wireless telephone systems. Orthogonal codes are used to combine data signals into one overall coded signal which is transmitted. The orthogonal codes are used to retrieve individual data signals from the transmitted overall coded signal. Despread instructions are included in the digital signal processor functionality.

Abstract: An orthogonal complex spreading method for a multichannel and an apparatus thereof are disclosed. The method includes the steps of complex-summing ?n1WM,n1Xn1 which is obtained by multiplying an orthogonal Hadamard sequence WM,n1 by a first data Xn1 of a n-th block and ?n2WM,n2Xn2 which is obtained by multiplying an orthogonal Hadamard sequence W1,n2 by a second data Xn2 of a n-th block; complex-multiplying ?n1WM,n1Xn1+j?n2WM,n2Xn2 which is summed in the complex type and WM,n3+jPWM,n4 of the complex type using a complex multiplier and outputting as an in-phase information and quadrature phase information; and summing only in-phase information outputted from a plurality of blocks and only quadrature phase information outputted therefrom and spreading the same using a spreading code.