Abstract: A method of and apparatus for adapting an antenna array for closed loop transmit diversity, the method comprising: receiving an adapting signal corresponding to an antenna array weighting pattern for a time period; demodulating the adapting signal to provide a symbol for the time period; determining a preferred symbol from the symbol for the time period and a previous symbol for a previous time period; and transmitting with an antenna array weighting pattern corresponding to the preferred symbol.

Abstract: A method of building systematically a multi-dimensional (n, D, L) circular trellis coded modulation (CTCM) encoder with properties of optimal energy efficiency, strong tail biting and maximum minimum distance (dmin) of trellis paths is disclosed.

Abstract: A communication system for communication with mobile stations through a plurality of base stations at macrodiverse locations and with frequency hopping (FH). Two or more adjacent base stations communicate with mobile stations in a region between the adjacent base stations using coordinated orthogonal frequency hopping sequences. The communication system operates with virtual cells formed of physical sectors from adjacent base stations. Where base stations each operate with three sectors, virtual cells use three adjacent sectors of three adjacent base stations, respectively, and the coordinated orthogonal frequency hopping sequences are used for the adjacent sectors of each of the virtual cells. For GSM, the coordinated orthogonal frequency hopping sequences in each virtual cell are defined by a single hopping sequence number (HSN) and a set of mobile allocation index offsets (MAIOs). Fast macrodiversity switching is employed in combination with FH.

Abstract: The invention relates to a method for equalizing symbols received from a transmission channel and for decoding data therefrom, the method being by performing either a first processing comprising a turboequalizing sequence on the received symbols or a second processing comprising an equalizing step followed by a turbodecoding sequence, the selection of the first or the second processing being made upon an estimation of the delay spread of the transmission channel.

Abstract: A block decision feedback equalizer is designed by deriving, from first principles, a block exact decision feedback equalizer and then systematically applying simplifying assumptions to obtain several block approximate decision feedback equalizers, each suitable for multipath channel equalization and having error convergence insensitive to filter length. The resulting block decision feedback equalizer is software definable may be dynamically adapted by choosing whether to update error correction coefficients.

Abstract: An improved analog front end and methods for increasing the power efficiency of duplex signals on a transmission line are disclosed. The improved analog front end bifurcates a hybrid into a fixed portion and an adaptive portion. The adaptive portion combines a biquad and a summer to produce a filter transfer function suited to compensate for transmission line irregularities. A method for configuring a local transceiver to minimize power requirements at a remote transmitter is disclosed. Broadly the method entails, applying a transmit signal to a front end in the absence of a remote signal; optimizing the transmit signal power; recording the reflected transmit signal; applying an adaptive filter in response to transmission line irregularities; and controllably adjusting the adaptive filter to minimize the amplitude of the reflected version of the transmit signal in the receive path. A method for recovering a remotely generated signal is also disclosed.

Abstract: A power estimator for a Code Division Multiple Access (CDMA) receiver. A noise estimate of a received channel may be made by demodulating a received signal using an empty code or Walsh channel. The noise estimate may also be made by demodulating the Pilot signal in systems where potentially all Walsh codes are assigned to active channels. Where the channels are quadrature phase modulated, the noise estimator may take advantage of the Pilot channel configuration by demodulating only the quadrature element of the Pilot channel. The noise estimator demodulates the Pilot using signal processing stages that statistically correspond to the signal processing performed on traffic channels. The statistics of the processing performed in the noise estimate closely track the statistics of the signal processing performed on the traffic channels.

Abstract: A method of compensating for carrier frequency and phase errors of a received multi-carrier modulated signal. The received multi-carrier signal including modulated carriers for transmitting known data and unmodulated carriers for error correction, comprising, time domain down converting the received multi-carrier signal to base-band to provide a down-converted signal, the down-converted signal including a plurality of modulated carriers for transmitting known data and unmodulated carriers for error correction. Sampling an unmodulated carrier of the down-converted signal to provide received data samples. Providing a reference signal derived from the unmodulated carrier of the down-converted signal. And, estimating phase errors from a phase difference between the ummodulated carrier and the reference signal derived from the unmodulated carrier of the down-converted signal to provide a plurality of received sample phase error estimates for each modulated carrier.

Abstract: Disclosed is a Universal Asynchronous Receiver/Transmitter, more particularly, an apparatus and a method for detecting an optimum baudrate. The method preferably includes calculating a number of samplings for each pulse width based on at least one pulse generated from received data; calculating an estimated baudrate and another number of samplings corresponding to the baudrate based on the number of samplings for each pulse width, respectively; and detecting an optimum baudrate based on the calculated sampling number. Advantageously, the speed of baudrate detection is improved, and data loss is reduced or eliminated.

Abstract: For use in a receiver capable of decoding trellis encoded signals, there is disclosed an apparatus and method for reducing error propagation in a two stage decision feedback equalizer. The apparatus of the invention comprises a first stage equalizer comprising a first forward equalizer filter, a first decision feedback equalization filter, and a trellis decoder. The apparatus of the invention also comprises a second stage equalizer comprising a second forward equalizer filter and a second feedback equalization filter. The two stage decision feedback equalizer is capable of obtaining symbol values from the trellis decoder and using the symbol values as estimates in channel equalization. In one embodiment of the invention, a two stage decision feedback equalizer is provided in which forward filter coefficients remain constant for the duration of D symbols.

Abstract: A method for demodulating a received digitally modulated signal subjected to multipath propagation impairment includes estimating the multipath propagation impairment of the received digitally modulated signal using a channel estimator, and estimating at least one symbol of the received digitally modulated signal using a symbol estimator. The at least one estimated symbol is adjusted based upon the estimated multipath propagation impairment to generate an estimate of the at least one symbol as impaired by the multipath propagation. At least one error signal is generated by comparing the estimate of the at least one symbol as impaired by the multipath propagation to the received digitally modulated signal. The at least one error signal is used for estimating remaining symbols to be demodulated and for refining the estimated multipath propagation impairment.

Abstract: The present invention relates to a method and apparatus for correcting frequency offset of a local oscillator in a direct sequence spread spectrum receiver such as Universal Mobile Telecommunications System (UMTS). Received signals comprise a plurality of sequential slots of data. At least one of these includes synchronization data. A correlation is performed between this received data and a locally stored synchronization code. Subsequently, the received data is phase adjusted and a further correlation performed between the phase adjusted data and the locally stored synchronization code. The strongest correlation peak is then determined and a phase offset to be applied to the local oscillator is estimated from the phase adjustment required to produce the strongest peak. This is subsequently applied to the local oscillator.

Abstract: A dynamic assignment of the spreading codes of a user in a CDMA system is based on multipath channel conditions of that user. The spreading codes are assigned such that multipath signal energies are coherently integrated at the antenna of the receiver to ensure that the multipath components are summed constructively and therefore that a signal gain is obtained. The method is applicable to any CDMA system which uses spreading codes over a multipath channel. A specific algorithm for selecting the codes based on channel parameters and auto-correlation functions of the spreading codes is proposed.

Abstract: A timing circuit for generating clock signals, includes an acquisition digital phase locked loop with a wide capture range for closely following an input signal with its associated disturbances. An output digital phase locked loop having a slow response relative to the acquisition phase locked loop tracks an output of the acquisition phase locked loop to generate an output signal for the timing circuit.

Abstract: Techniques for time tracking diversity pilots are disclosed. In one aspect, an early and a late energy calculation is made on each incoming symbol using a first pilot sequence for despreading. The difference between the two energies is used to drive a tracking loop, which generates a time reference for producing a first pilot estimate and a second pilot estimate, the two estimates used for demodulating data. In another aspect, the early and late energies are made including a plurality of incoming symbols, the number of which corresponds to the number of symbols in a run of positive or negative values in an orthogonalizing sequence. The orthogonalizing sequence is used to generate a second pilot sequence from a first pilot sequence, the resulting second pilot sequence being orthogonal to the first. These aspects have the benefit of simplifying the hardware or processing steps required for transmit diversity time tracking, resulting in cost savings, power savings, simplicity of design, and the like.

Abstract: A receiver may receive ultra-wideband, spread-spectrum differential signals. In some embodiments, the receiver may use a variable bandwidth low pass filter. Lowering or raising the bandwidth of the low pass filter may improve performance in particular wideband signal situations.

Abstract: This invention describes an apparatus and method to improve the performance of a decision feedback equalizer (DFE) for time-varying multi-path channels. For minimum-phase channels, the equalization is performed in a time-forward manner. For maximum-phase channels, the equalization is performed in a time-reversed manner. More specifically, for maximum-phase channels, the filter coefficients are computed based on the channel estimates reversed in time, and the filtering and equalization operations are performed with the received block of symbols in a time-reversed order. In the context of this invention, the term “minimum-phase channel” implies that the energy of the leading part of the channel profile is greater than the energy of the trailing part. The term “maximum-phase channel” implies that the energy of the leading part of the channel profile is less than the energy of the trailing part.

Abstract: Standard analog modems (modulator-demodulator devices) are currently commonplace in the home and office environments, where they are used to enable electronic devices, such as personal computers, to transmit data over existing telephone lines (made of small gauge copper wire) to other electronic devices. Data is stored digitally in such devices, but is converted by an analog modem to be transmitted over the lines in analog form. A data stream is established between a sender (i.e., originating electronic device) and a receiver (i.e., receiving electronic device) by using the resources of an entire telecommunications system. In other words, data is transmitted from the sender's local loop, through the telephone switching system, and to the receiver's local loop. Because the lines used by analog modems to transmit data only use a frequency range of about 0–3400 Hz, a data transmittance limit of about 56,000 bits-per-second (bps) exists for communication through the lines.

Abstract: A method for equalizing and decoding an error-protected data signal transmitted via a radio channel is described. According to the method, an equalized data signal is calculated at the receiving end in a demodulator with a first channel estimator. The equalized data signal is decoded by a decoder to determine a decoded output signal. The equalized data signal is transmitted to a second channel estimator, which repeatedly detects second channel parameters of the radio channel. The parameters are transmitted to the decoder which uses them as calculation parameters during decoding.

Abstract: The present invention relates to a digital broadcasting receiving apparatus for generating a display signal from a received digital broadcasting signal. The apparatus comprises a detection section, a storage section, and a recording section. The detection section detects occurrence of an interrupt event overlapped with the digital broadcasting signal when displayed. The storage section starts storing digital broadcasting signals based on a detection result of this detection section. The recording section records information corresponding to a reproduction start position of the digital broadcasting signal stored by this storage section.