Abstract: The invention discloses a method for determining the occupancy of a transmission channel with the help of a differentially demodulated signal, which was generated transmitter-side with the use of PN sequences from a PN sequence set, which has a first group of first PN sequences and a second group of second PN sequences, wherein the first and second PN sequences within their respective group differ from one another in a cyclic shift of their chip values and wherein the second group has for each first PN sequence a corresponding second PN sequence, which differs from the first PN sequence in an inversion of every second chip value.

Abstract: A wireless local area network receiver is provided that has an interference reduction unit for reducing interchip interference in a received signal that is modulated using a complementary code keying technique such as CCK-11. The interference reduction unit comprises a decision feedback equalizer that has a feedforward filter for reducing precursor interference and a feedback filter for reducing postcursor interference in the received signal. The receiver may perform channel estimation to optimize the filter coefficients during the preambles of the incoming sequence.

Abstract: A data communications technique is provided that may be used in WLAN (Wireless Local Area Network) receivers. Data signals modulated in accordance with one of at least two different modulation schemes are received. The front end of the device has an analog and a digital part, and the digital front end includes a first and a second signal processing branch for processing received data signals modulated in accordance with different modulation schemes. The first and second processing branches have low-IF (Intermediate Frequency) topologies. There is further provided a corresponding integrated circuit chip and a method of processing received data signals.

Abstract: A method and a circuit (44) for estimating channel coefficients in a multi carrier transmit diversity system operating in accordance with a block-coding scheme is described. The method comprises determining from a receive signal (Y) for each channel estimated channel coefficients (ĥ) comprising interference components from adjacent channels artificially introduced during the estimation, deriving estimates for interference components and determining interference-compensated estimates (ĤF+IC) for the channel coefficients on the basis of the estimates for the interference components.

Abstract: The invention relates to a method of multiplexing data words in a multicarrier transmit diversity system. The method comprises the step of generating a plurality of data blocks, each data block comprising data words and each data word containing data symbols derived from a data signal, the step of determining for one or more data blocks in dependence on at least one transmission constraint if the data words of said one or more data blocks are to be multiplexed in the time domain or in the frequency domain and the step of multiplexing the data words of the data blocks in accordance with the determination result.

Abstract: An improved data communication receiver technique is provided which avoids demodulation errors due to abrupt phase changes. A receiver is provided for processing an incoming digitized signal. The receiver comprises a pre-processing portion, a phase error correction unit and a signal evaluation unit. The pre-processing portion is adapted to process the digitized signal for providing a non-coherent pre-processed signal. The phase error correction unit is adapted to correct a phase error of the non-coherent pre-processed signal and output a coherent signal. The signal evaluation unit is adapted to extract information from the non-coherent pre-processed signal and to output a data signal representing the extracted information. The phase error correction unit and said signal evaluation unit are configured to operate simultaneously for a predetermined time.

Abstract: A WLAN (Wireless Local Area Network) receiver with a synchronization unit is provided, wherein the synchronization unit comprises a frequency error correction unit configured to perform a frequency error correction process, a phase error correction unit configured to perform a phase error correction process, a filter circuit capable of applying one of at least two different filter transfer functions, wherein a first one of said at least two different filter transfer functions is a frequency error correction filter transfer function for use in said frequency error correction process and a second one of said at least two different filter transfer functions is a phase error correction filter transfer function for use in said phase error correction process, and a controller unit connected to said filter circuit to select one of said at least two different filter transfer functions.

Abstract: A complementary code decoder technique is provided where the encoded input data is first parallelized. From the parallelized data, correlation values are generated by a correlator circuit that is capable of changing its correlation characteristics depending on at least one control signal. Different control signals are sequentially provided to the correlator circuit thereby driving the correlator circuit to sequentially generate multiple correlation values from the parallelized data, based on different correlation characteristics. From the multiple correlation values, the correlation value that represents the optimum correlation is identified. This technique significantly reduces the gate count of the decoder structure, thus saving chip area and manufacturing costs.

Abstract: An improved decision feedback equalization technique is provided that may be used in data communications receivers such as those in WLAN (Wireless Local Area Network) systems. The decision feedback equalizer comprises a feedforward filter that is connected to receive an input data signal and output a filter representation thereof. The feedforward filter has a filter characteristic that depends on filter coefficient data. The decision feedback equalizer further comprises a filter coefficient computation unit for generating the filter coefficient data and outputting the generated data to the feedforward filter. At least one data processing circuit is provided that receives a mode switch signal for switching its operational mode. The data processing circuit is arranged for performing a feedforward filter function in one operational mode and a filter coefficient computation function in another operational mode.

Abstract: A phase error corrector circuit and method are disclosed. In one embodiment, a phase error corrector circuit delays a PSK modulated signal and multiplies the delayed PSK modulated signal by the PSK modulated signal in order to generate a forward phase correction signal. The input signal is then mixed with the forward phase correction signal. In another embodiment, a phase error corrector circuit calculates a forward phase offset of a complex PSK modulated signal. The complex PSK modulated signal is phase shifted in a mixer by a phase difference offset in order to generate a phase corrected signal. A backward phase correction means calculates a backward phase offset based on the phase corrected signal. A subtractor subtracts the forward phase offset from the backward phase offset for outputting a difference phase offset to the mixer.

Abstract: A technique for performing a frequency error correction process is provided that may be used in receivers of wireless local area network systems. The technique comprises a three-phase process generating a frequency approximation value based on a frequency error estimate, starting a channel estimation process that uses the generated frequency approximation value, refining the generated frequency approximation value, and compensating a frequency error using the refined frequency approximation value. Further, a corresponding integrated circuit chip and an operation method are provided. Using the technique for performing a frequency error correction process may provide high reliability, high precision and improved operation speed.

Abstract: A phase error correction technique in receivers such as WLAN receivers is provided. Such receivers comprise a phase error correction unit connected to receive an input signal having a phase error and adapted to generate an output signal having a corrected phase error. Further, the receiver comprises a despreader which is adapted to despread a data signal. The despreader is connected to the phase error correction unit to provide the despread data signal to the phase error correction unit. The phase error correction unit is arranged for correcting the phase error dependent on the despread data signal. The despreader may be a Barker matched filter or a CCK matched filter, and there may be provided a multiplexer for selecting one of the filters.

Abstract: An antenna diversity method and a corresponding communication device are disclosed that may be used in wireless LAN receivers. An AGC (Automatic Gain Control) unit controls a gain when processing signals received from antennae. A periodical switching process is performed between at least two antennae. During this periodical switching process, signals from each of the antennae are received alternately. The gain obtained by processing each received signal by means of the AGC unit is monitored and the obtained gain is compared with a predetermined threshold value. When for one of the at least two antennae the gain is below the predetermined threshold value, the periodical switching process is stopped and the antenna used at the time when stopping the periodical switching process is selected. This technique may provide an improved antenna diversity of low complexity, high performance and a short settling time.

Abstract: A wireless local area network receiver is provided that has an interference reduction unit for reducing interchip interference in a received signal that is modulated using a complementary code keying technique such as CCK-11. The interference reduction unit comprises a decision feedback equalizer that has a feedforward filter for reducing precursor interference and a feedback filter for reducing postcursor interference in the received signal. The receiver may perform channel estimation to optimize the filter coefficients during the preambles of the incoming sequence.