Abstract: A process for synchronization of an input signal (S) involves demodulating (5a) the input signal (S) according to a particular demodulation method (AM) using a particular signal parameter for creation of a demodulated input signal (SAM); correlating (6a) the demodulated input signal (SAM) with a comparison signal (f (AM,Signal)) which depends on the demodulation method (AM) to determine a time offset (?) between the demodulated input signal (SAM) and the comparison signal (f (AM,Signal)); and time displacing, or shifting, the input signal through the time offset (?) calculated from the correlation.

Abstract: The present invention relates to the reduction of artifacts introduced by sending data at a higher rate than the bandwidth of the communication channel, such as the voltage and current offsets introduced in the data at the receiver as a function of the preceding data.

Abstract: The invention provides an adaptive turbo decision feedback equalizer for executing an adaptive turbo decision feedback equalization method in response to a reception a packet including samples transmitted to the adaptive turbo decision feedback equalizer via a channel. The adaptive turbo decision feedback equalizer generates a first set of soft estimates of bits based upon a computation of a first feed-forward filter and a first feedback filter as a function of an estimation of the channel. The adaptive turbo decision feedback equalizer subsequently generates additional sets of soft estimates of the bits and a set of hard estimates of the bits based upon a computation of additional feed-forward filters and additional feedback filters as a function of a plurality of additional soft symbol estimates.

Abstract: A method including searching for a pilot signal of a second communications system while retaining the connection with a first communications system.

Abstract: A method for estimating the impulse response of an information transmission channel includes evaluating a useful number of coefficients of an impulse response of the information transmission channel as a function of actual characteristics of the information transmission channel. This evaluation is carried out, for example, by using a time domain spreading parameter of the channel.

Abstract: Each of first and second stations, in communicating with the other station, provides a preamble including forward link parameters and reverse link parameters. The forward link parameters in each preamble for each individual station are provided for each station in accordance with the reverse link parameters previously transmitted to the station in packets from the other station. The reverse link parameters in each preamble in each individual station provide an indication to the other station of the forward link parameters to be provided by the other station in the next transmission of a packet to the individual station from the other station. Data is provided in packets at each station to be transmitted to the other station. Each packet transmitted by each station to the other station includes a preamble and includes data after the preamble.

Abstract: A long code scrambler has been provided to scramble the data bits prior to QAM mapping. Different data rates are accommodated by using different long code m-tuples sampled at the modulation symbol rate, where m equals 2, 4 or 6 for 4, 16 or 64 QAM, respectively. In order to support 1XEV-DV users employing multiple Walsh code channels, a long code 6-tuple sample is permutated, to further randomize the QAM symbols. As appropriate for the modulation order, 2, 4 or 6 bits of the permutated 6-tuple are applied to the data sequence. That is, in addition to randomizing the modulation symbols for a given code channel, each code channel will likely have unique QAM symbols at any given symbol time.

Abstract: A method and an apparatus relating to a fine frequency synchronization compensating for a carrier frequency deviation from an oscillator frequency in a multi-carrier demodulation system of the type capable of carrying out a differential phase decoding of multi-carrier modulated signals, the signals comprising a plurality of symbols, each symbol being defined by phase differences between simultaneous carriers having different frequencies. A phase difference between phases of the same carrier in different symbols is determined. Thereafter, a frequency offset is determined by eliminating phase shift uncertainties related to the transmitted information from the phase difference making use of a M-PSK decision device. Finally, a feedback correction of the carrier frequency deviation is performed based on the determined frequency offset. Alternatively, an averaged frequency offset can be determined by averaging determined frequency offsets of a plurality of carriers.

Abstract: A modulation/demodulation device capable of operating with several types of modulation using different carrier frequencies may include a modulator which modulates at least one signal by a signal of a predetermined duration and representative of a binary information supplied by a microprocessor. The device may also include a demodulator which demodulates the modulated signals arriving from a remote site. This may be done by determining the type of modulation of the received signals and their carrier frequency (or frequencies), supplying signals from an analysis of the signals received according to the determined type of modulation, and detecting the signals of determined duration representative of binary information to make them accessible to the microprocessor.

Abstract: The present invention is related to a Rake receiver (R1) for receiving a radio signal and to a searcher (S8a, S8b) for estimating the delay profile of one or more radio links. The searcher includes means for estimating delay profiles in separate windows. The searcher is arranged for being switched into a single window mode or alternatively into a multiple window mode. In single window mode the delay profiles of separate radio links are estimated in the windows, while in multiple window mode two or more windows are allocated adjacent in time for estimating the delay profile of the same radio link. Thereby, the use of the resources of the searcher can be adapted to the radio environments in which the searcher will be used. The Rake receiver comprises fingers that are grouped into two sets. Within a set of fingers the propagation paths are time aligned. The output from the two set of fingers are time aligned and then combined.

Abstract: This invention, generally speaking, modifies pulse amplitude modulated signals to reduce the ratio of average power to minimum power. The signal is modified in such a manner that the signal quality remains acceptable. The signal quality is described in terms of the Power Spectral Density (PSD) and the Error Vector Magnitude (EVM).

Abstract: In order to perform synchronization detection with high speed, high precision and high reliability and to measure communication quality (propagation characteristics) at high precision and high efficiency, a mobile station includes synchronization detecting portion for detecting synchronization chip timing of channel to be measured, a synchronization chip timing information portion accumulating information of detected synchronization chip timing, a correlation detecting portion deriving a correlation value between spreading code of the channel to be measured and a received signal for performing communication with a base station and measurement of communication quality with taking the detected synchronization chip timing as a reception chip timing, a time series generating portion for generating a time series data of received signal vector after correlation detection, and a communication quality calculating portion for calculating communication quality from generated time series data.

Abstract: A novel and useful channel tracking mechanism operative to generate channel estimate updates on blocks of samples during reception of a message. The tracking mechanism is based on the weighted recursive least squares algorithm and implements the estimation process by recursively updating channel model parameters upon the arrival of new sample data. The mechanism is operative to update channel estimate information once per sample block. An interblock exponential weighting factor is also applied. The block length is chosen short enough to enable good tracking performance while being sufficiently long enough to minimize the overhead of generating preliminary decisions and of updating precalculated tables in the equalizer. The method of the invention can be performed in either hardware or software. A computer comprising a processor, memory, etc. is operative to execute software adapted to perform the channel tracking method of the present invention.

Abstract: An adaptive equalizer for amplitude-modulation (AM) signal received by over-the-air radio transmission comprises feed-forward finite-impulse-response (FIR) filtering and further comprises infinite-impulse-response (IIR) filtering for feeding back decisions. The echo content of baseband signal demodulated from the AM signal is measured for initially determining the reception channel impulse response (CIR) in the time-domain. Thereafter, the CIR is updated by decision feedback. Periodically, the CIR is normalized with respect to the strength of a cursor component thereof. The strengths of longer-delay post-echoes in the normalized CIR are used to determine the weighting coefficients of the IIR filtering, which suppresses the longer-delay post-echoes. The pre-echo and short-delay post-echo portion of the normalized CIR is convolved with the normalized CIR to generate a synthetic normalized CIR.

Abstract: A digital and a multiplication method are described, which lead to an efficient architecture for a hardware implementation of digital FIR and IIR filters into FPGAs. The multiplications of input sample data and delayed sample data with filter coefficients are performed by addressing look-up tables in which corresponding multiplication results are prestored. The size of the look-up tables is reduced by storing only those multiplication results which cannot be obtained by a shifting operation performed on the other pre-stored multiplication results, the input sample data, or the delayed sample data. Thereby, the size of the look-up tables can be compressed significantly such that an implementation of large digital filters into FPGAs is possible.

Abstract: A plurality of input signals are pre-distorted for combination into a first combined signal having a constant envelop. The input signals are combined into a second combined signal, and a similarity between each of the input signals and the second combined signal is measured. Ones of the input signals are selected and attenuated based on the similarity measurement. The attenuated input signals and non-attenuated signals are output for combination to form the first combined signal.

Abstract: In a data demodulating method, predetermined input data is demodulated based upon a response characteristic of the partial response class 4; the demodulated input data is discrete-filtered to thereby produce filtering data; and the filtering data is maximum likelihood-decoded to thereby produce asymmetrical response data. Further, a magnetic recording/reproducing apparatus is arranged by using this data demodulating method.

Abstract: A dual-mode ultra wideband (UWB) and wireless local area network (WLAN) communication transceiver is used to implement two disparate systems of UWB and WLAN communications within a single device. During the UWB mode, the communication transceiver sends and receives the UWB signal at very-high data rate with a relative short transmission range. During the WLAN mode, the communication transceiver sends and receives the WLAN signal at a relative low data rate, but with a longer transmission range. Thereby, trade-off benefits of the dual-mode UWB and WLAN communication transceiver can be mutually utilized to achieve seamless wireless broadband communications between two different standards.

Abstract: A multiple integration hypothesis C/A code acquisition system resolves bit boundaries using parallel correlators providing magnitude hypotheses during acquisition to reduce losses over the 20 ms integration period to improve the performance and sensitivity of C/A code receivers to achieve low C/No performance using inexpensive, imprecise oscillators and long noncoherent dwell periods, well suited for in-building, multipath, and foliage attenuated GPS signaling applicable to E911 communications with several dB of additional improvement in receiver sensitivity due to the ability to detect bit synchronization during acquisition.

Abstract: A device includes a receiver including an estimation block for estimating the impulse response of the transmission channel and a transformation block. The transformation block may include a preprocessing block for determining a phase minimum transformed impulse response corresponding to a transformed channel based upon the estimated impulse response of the transmission channel, and a filter for filtering the signal received. This makes it possible to retain equality between the autocorrelation of the signal received and the autocorrelation of the filtered signal. Further, the receiver may include an equalizer for applying an equalization processing operation to the filtered signal while taking account of the transformed impulse response.