Abstract: A first node initiating communications with a second node already in a secure network sends a discovery burst having a preamble portion and a payload portion. The preamble portion is sent at a varying frequency between high and low thresholds that are reflective of Doppler uncertainty between the nodes. The second node continuously listens at a frequency, termed an acquisition frequency. A data sequence in the preamble portion, known to the second node, is received and used to determine the receive instant in the preamble portion, and thereby compare against the known frequency ramp to determine the frequency at which the payload portion will be received. Preferably, the first node varies the preamble portion between thresholds more than once within the time span of a single preamble portion, and the preamble and payload portions are spread with different spreading codes. The preamble portion may also be disguised with noise generated by the first node.

Abstract: A system and method for determining a fine frequency offset of a composite code spread spectrum signal is disclosed. The method includes despreading at least one component of the composite spread spectrum signal to form a partially despread composite spread spectrum signal. A set of on-time samples are selected from the signal. The set of on-time samples are rotated by a predetermined frequency amount. The set of rotated samples are placed into a plurality of frequency bins, with each frequency bin representative of a different frequency estimate. An energy for the signal in each frequency bin is determined to find the bin having the greatest energy.

Abstract: A correlator despreads a P/N long code constructed from two or more constituent codes A, B, C having N, M and L elements respectively. In a third stage, L filter taps decorrelate elements of the third constituent code from the input received signal, leaving elements of code AB. The outputs of the third stage delay line are summed and input into a second stage delay line having M filter taps to decorrelate the elements of the second constituent code from the input to the second stage, leaving elements of code A. The outputs of the second stage delay line are summed and input to a first stage delay line having N filter taps. The output of the first stage delay line is summed and input into a shift register. An energy peak in the shift register indicates the phase of the P/N elements in the register is proper.

Abstract: A multimode communication device with a shared signal path programmable filter and a method for utilizing a shared signal path programmable filter in a multimode communication device. Various aspects of the present invention comprise a first module adapted to receive a first communication signal (e.g., corresponding to a first communication protocol) and a second module adapted to receive a second communication signal (e.g., corresponding to a second communication protocol). A shared filter, communicatively coupled to the first and second modules, may be adapted to filter the first and/or second communication signals in accordance with a plurality of selectable sets of filter response characteristics (e.g., associated with the first and second communication protocols). A filter control module may be adapted to select a set of filter response characteristics from a plurality of such sets and program the shared filter to filter a communication signal in accordance with the selected set.

Abstract: The frame of data is partitioned into a plurality of portions of data symbols. A plurality of channel elements is assigned to demodulate data symbols of correspondingly the plurality of portions of data symbols. The number of the plurality of portions of data symbols is higher in a case at high data rate than a case at low data rate.

Abstract: A Kerdock decoder of the present invention generates correlation reliability from a relation between correlation values to output together with a Kerdock-decoded map data. A map deciding unit receives a field sync signal, a field identifying signal, the Kerdock-decoded map data and the correlation reliability to identify whether a current field is an odd or even field and whether there is a map change in case of the even field. And, the map deciding unit decides a current map data by performing map acquisition and tracking according to the corresponding result.

Abstract: An apparatus for detecting symbol synchronization in a received signal including a first preamble and a second preamble which is consecutive to the first preamble, the apparatus including a first correlator calculating a first correlation value between the received signal and a first pattern of a first period among iterative patterns of the first preamble, a second correlator calculating a second correlation value between the received signal and a second pattern of a second period among iterative patterns of the second preamble, a third correlator calculating a third correlation value between the first correlation value and the second correlation value, and a detector detecting symbol synchronization from the third correlation value.

Abstract: A packet detector for a multi-band orthogonal frequency division multiplexing system includes a plurality of packet detection units each corresponding to a time frequency code for detecting packets according to a spreading sequence of the time frequency code, a comparison unit for comparing correlation values provided by division units of the plurality of packet detection units, and a packet decision module for determining a time frequency code and size of a fast Fourier transform sampling window according to output signals of the comparison unit, allowing a frequency band to be selected and synchronization to be executed.

Abstract: The invention discloses a method of applying a long cell-code in a joint detection system. At transmitters, multiples of the spreading code (spreading factor) is taken as the length of the long cell-code to scramble the signal, and at receivers, the method still takes the multiuser detection to process the received signal.

Abstract: A method and apparatus for a spread spectrum matched filter with Doppler correction suitable for using in a radio frequency receiver. The system includes a signal sampler operable to receive signal data and a Doppler shift system operable to provide a Doppler shift correction value. The system also includes a time domain signal processor in signal communication with the signal sampler, the Doppler shift system and the code signal input, the time domain signal processor operable to shift the signal data by the Doppler shift correction value and to determine a correlation between the shifted signal data and the code signal input. The system reduces a waveform representing Doppler correction values into a Boolean combination that may selectively represent the waveform and be implemented by the processing of a matched filter.

Abstract: A composite code is made for example by exclusive-OR'ing each real element of a first constituent code A with each element of a second constituent code B to obtain a basic composite code. To suppress autocorrelation, differing numbers of doping code elements are inserted between code segments made from combining each element of code A with an element of code B. A matched filter first stage removes from its input the A code and any doping code added to it, summing the elements of code A. A matched filter second stage removes from its input the B code and any doping code added at the second level. The summed elements of code B are the input to the first stage. Optionally, the summed elements of the doping code at any level may be delayed and summed with the elements of the A code in the first stage.

Abstract: A digital broadcasting receiver, a driving method, and a self-diagnosis method thereof, are provided. The digital broadcasting receiver includes: a digital demodulator for demodulating a digital broadcasting signal; a lock detector for detecting lock signals from the digital demodulator; and a lock processor for controlling the digital demodulator according to the detected lock signal.

Abstract: A system and method for fast synchronization of an incoming signal with a UWB receiver. The present invention synchronizes a UWB receiver with an incoming signal. The present invention correlates a local pulse generated at the receiver with the incoming signal, finds the value in the correlation function that would correspond to a high signal to noise ratio, thereby matching the receiver to the incoming signal phase, and operates the receiver at that phase. Exemplary options of fast synchronization include a maximum peak detector.

Abstract: Provided are a pulse signal generator for UWB radio transception and a radio transceiver having the same. The pulse signal generator includes: an envelope generator generating a plurality of envelope signals; a local oscillator array composed of a plurality of high frequency oscillators, each outputting two oscillation signals having a phase difference from each other; a multiplier array receiving the envelope signals and the oscillation signals and outputting signals obtained by respectively multiplying the envelope signals by the oscillation signals; and an I channel adder and a Q channel adder outputting an I channel pulse signal and a Q channel pulse signal by adding output signals having the same phase components among the signals output from the multiplier array, respectively.

Abstract: In a baseband processing unit in a node-B, a path search circuit includes a path capture unit, path track transfer unit, and channel estimation unit, all of which are primarily provided for the path capture, channel estimation, and RAKE combination. In the baseband processing unit, a synchronization determination circuit includes a decoding unit provided for decoding RAKE-combined data and calculating an average SIR per wireless frame and a correction calculation unit primarily provided for reliably and stably detecting wireless frame synchronization. The processing time required to detect synchronization establishment during wireless frame synchronization determination is shortened.

Abstract: An apparatus for compensating nonlinearly distorted multicarrier signals, a multicarrier signal receiver using the same, and a method therefor are provided, where the apparatus for compensating multicarrier signals and the multicarrier signal receiver using the apparatus extract parameter information on the HPA mode from the received signal so that nonlinear distortion of the received multicarrier signal is compensated for even though an accurate transfer function of a high power amplifier (HPA) is not known and side information or a special training signal is not transmitted when a signal is transmitted, such that nonlinearly distorted multicarrier signals such as OFDM signals transmitted by an HPA having a variety of transfer functions can be adaptively compensated and therefore a demodulated signal with an improved symbol error rate (SER) can be obtained.

Abstract: A method for synchronizing interconnects in a link system according to various embodiments can include receiving input data at a transmit side, the transmit side including at least one pseudo-random bit sequence scrambler; scrambling the input data at the transmit side via the pseudo-random bit scrambler with dual tap sequences resulting in scrambled data; transmitting the scrambled data with the dual tap sequences along all lanes of a plurality of lanes to a receive side via a bus interconnecting the plurality of lanes, the receive side including at least one pseudo-random bit sequence descrambler; synchronizing the at least one pseudo-random bit sequence scrambler to the at least one pseudo-random bit sequence descrambler; using an edge detection or transition detection device for synchronization of the descrambler to the scrambler; and de-scrambling the transmitted scrambled data at the receive side resulting in the input data.

Abstract: Disclosed is a method for decoding received signals on communication channels between at least one transmit antenna and plural receive antennas in a space-time coded direct sequence (DS)-CDMA communication system. The decoding method includes steps of: adjusting the step-size which is an update unit for the tap weight vector for despreading received signals; updating the tap weight vector using the step-size; and despreading the received signals using the tap weight vector. According to the decoding method, the optimal performance can be achieved because the tap weight vector and the step-size are adaptively updated according to changes of communication environment. Such superior performance is more remarkable as the number of receive antennas and transmit antennas increases.

Abstract: The present invention is a method and system for receiving data transmitted using block space time transmit diversity (BSTTD) in a code division multiple access (CDMA) communication system. The system comprises a transmitter, for transmitting a first data field using a first antenna and a second data field using a second antenna, and a receiver. The receiver includes an antenna for receiving the first and second transmitted data fields, and a BSTTD joint detector which determines symbols of the first and second transmitted data fields using a minimum mean square error block linear equalizer model and an approximated Cholesky decomposition of the model.

Abstract: System and method for detecting multiple direct sequence spread spectrum signals using a multi-mode searcher. A preferred embodiment comprises the specification of a hypothesis for a particular communications network. The hypothesis can then be used to generate a pseudo-random number (PN) sequence that is provided to a searcher. The searcher can then make adjustments to the PN sequence to bring the PN sequence to conformity with requirements of the particular communications network. The adjustment to the PN sequence permits the use of a multi-mode searcher to perform searches for signals of various communications networks with minimal hardware dedicated to each communications network.

Abstract: A method and apparatus are provided for adapting a pilot filter based on the velocity of a wireless communication device (WCD) in relation to a wireless network infrastructure. The pilot filter is adapted by determining pilot coefficients for the pilot filter based on the WCD velocity. The pilot filter may be located in the WCD, or in the network infrastructure, or in both.

Abstract: A method of transmitting communications codes is used in spread spectrum communications systems. The method includes transmitting a first pseudo-noise code, and transmitting a second pseudo-noise code, wherein the second pseudo-noise code is a time-reversed version of the first pseudo-noise code. A device includes a first shift register to store a first code and a second register to store a second code in a time-reversed version. A comparison circuit then compares the two codes and a result is output.

Abstract: Signal processing architectures for direct acquisition of spread spectrum signals using long codes. Techniques are described for achieving a high of parallelism, employing code matched filter banks and other hardware sharing. In one embodiment, upper and lower sidebands are treated as two independent signals with identical spreading codes. Cross-correlators, in preferred embodiments, are comprised of a one or more banks of CMFs for computing parallel short-time correlations (STCs) of received signal samples and replica code sequence samples, and a means for calculating the cross-correlation values utilizing discrete-time Fourier analysis of the computed STCs. One or more intermediate quantizers may optionally be disposed between the bank of code matched filters and the cross-correlation calculation means for reducing word-sizes of the STCs prior to Fourier analysis. The techniques described may be used with BOC modulated signals or with any signal having at least two distinct sidebands.

Abstract: A method and system for simulcasting are provided. The method includes modulating a simulcast signal using 8-level modulation, increasing a spacing between signal pulses of the simulcast signal and spreading in time the signal pulses of the simulcast signal. The method further includes communicating a stretched modulated simulcast signal formed by increasing the time interval spacing and spreading in time the signal pulses.

Abstract: There are provided input route selecting means 711-713 and 723-725 for selecting, in accordance with the oversampling phase, input routes along which reception data and codes are to be input to individual shift register means, a plurality of data shift register means 707-710 that are caused by the input route selecting means to operate in groups corresponding to respective oversampling phases, code shift register means 719-722 corresponding to the respective data shift register means 707-710, and despreading integration calculating means 702 and 704. Correlation calculations are performed while reception data are stored in the tap groups efficiently, whereby the search window width is increased when the oversampling setting number is low. Further, the power consumption is reduced by lowering the shift frequency of the shift register means.

Abstract: A signal transmission and reception device is disclosed that can be made compact and has wide-band band-pass characteristics. The signal transmission and reception device includes a first filtering unit that is composed of a distributed constant circuit and is capable of eliminating a first frequency component or a second frequency component. The second frequency is higher than the first frequency, and a second filtering unit that attenuates components of frequencies lower than the first frequency or components of frequencies higher than the second frequency.

Abstract: A multicarrier receiver sequentially correlates two training symbols to determine a length of a cyclic prefix associated with each of the training symbols.

Abstract: An A-D conversion unit performs analog-to-digital conversions on baseband signals. A correlation processing unit carries out a correlation processing. A power computing unit computes the power of correlation values. An inter-signal condition determining unit compares a relationship between the peak of a main signal and the peak of sub-signals to a first condition, and excludes, from combining diversity, baseband signals corresponding to the sub-signals if the relationship does not satisfy the first condition. An intra-signal condition determining unit 30 compares the main signals and sub-signals to a second condition, respectively, and excludes signals from combining diversity if the signals do not satisfy the second condition. A timing adjusting unit adjusts the timing of sub-signals so that the timing thereof comes close to the timing of the main signal. A shift unit shifts the timing of sampled signals corresponding to the sub-signals.

Abstract: In a wireless communication system which includes a synchronization signal generator which generates a synchronization sequence, an RF transmitter which transmits the synchronization signal, and one or more receiver that receives the signal, where the synchronization sequence employs M PN codes of the same length that are repeated in a pseudo-random fashion for N code periods. Each receiver incorporates M filters matched to the M PN codes whose outputs are post detection combined in a manner consistent with the pseudo-random code transmission sequence to provide signal detection and synchronization. In another aspect, the synchronization sequence employs M time-shifted versions of a PN code that are repeated in a pseudo-random fashion for N code periods and each receiver incorporates a filter matched to the unshifted PN code and whose output samples are post detection combined in a manner consistent with the pseudo-random code transmission sequence to provide signal detection and synchronization.

Abstract: A semiconductor integrated circuit for processing a plurality of received broadcast signals, such as GPS signals, is operable in two modes: acquisition and tracking. In an acquisition mode, sample reducer combines samples of a received signal for correlation with a locally generated version of a GPS code. In a tracking mode, the sampled signal is provided direct to the correlators without sample reduction. The same correlators are thereby used to increase acquisition speed.

Abstract: A semiconductor integrated circuit for processing a plurality of received broadcast signals, such as GPS signals, is operable in two modes: acquisition and tracking. In an acquisition mode, a memory arrangement comprising two circulating shift registers circulates samples of a received signal for correlation with a locally generated version of a GPS code. In a tracking mode, the sampled signal is provided direct to the correlators. The same correlators are thereby used to increase acquisition speed.

Abstract: A RAKE receiver circuit generates combining weights based on channel estimates and combining statistics that comprise channel coefficient statistics, noise statistics, and channel estimation error statistics. Together, these statistics incorporate the relationships in noise and channel estimation across two or more RAKE fingers, and thus improve combining weight generation. Exemplary determination of statistics comprises channel coefficient cross-correlations, noise cross-correlations, and channel estimation error cross-correlations. Determination of the statistics can be varied based on, for example, the assumption of default or nominal signal models.

Abstract: Briefly, in accordance with one embodiment of the invention, a channel estimator may be adapted to provide a channel estimate based at least in part on an estimated delay spread. The channel estimator may be adapted to provide a more accurate channel estimation in the event of a lower estimated delay spread. In one embodiment, the channel estimator provides a frequency domain channel estimate, and in another embodiment the channel estimator provides a time domain channel estimate.

Abstract: The ultra wide band communication system of the present invention includes a transmitter (station) and a receiver (station). The transmitter and the receiver employ spreading code comprised of code groups, which respectively comprise varied, auto-correlated codes. Consecutive information bits are spread and de-spread with differing code and the code groups are correlated with each other (e.g., orthogonal) so as to reduce channel impulse response estimation noise. At the receiver, subsequent channel estimates can be added or averaged with an initial channel estimate so as to reduce the channel impulse response estimation noise and thereby provide a relatively more accurate channel response.

Abstract: Provided is a method of compensating for energy loss and eliminating inter-symbol interference (ISI) and inter-chip interference (ISI) in wireless signals, and a rake receiver for wireless LANs adopting the same. The rake receiver compensates for energy loss of a CCK signal transmitted in a multi-path wireless channel environment and eliminates ISI and ICI from the received CCK signal because a DFE structure per chip used for calculating ICI components, is connected in parallel with a DFE structure per symbol, thus eliminating ISI and ICI components.

Abstract: A method for detecting the presence of a transmission signal in a wireless spectrum channel. The frequency of a signal is converted from a first frequency to a second frequency. The signal with the second frequency is filtered to remove signals that are not within the band of the second frequency. An averaged periodogram of the signal is calculated. A value of the averaged periodogram is compared to a threshold. The presence of the transmission signal is detected, if the value of the averaged periodogram exceeds the threshold.

Abstract: An ultra-wideband transmitter and receiver, and a ultra-wideband wireless communication method, which perform ultra-wideband wireless communication by a low-speed digital circuit having a low power consumption and controlling the effect of a multi-pass. In ultra-wideband transmitter, delay time controller generates and inputs a periodic pulse to a first matched filter, outputs the periodic pulse to a second matched filter when data to be transmitted are at a first level of a binary logic level, and outputs the periodic pulse to a third matched filter when the data to be transmitted are at a second level of the binary logic level. The first matched filter receives the periodic pulse from the delay time controller and outputs a reference signal for data determination the second matched filter receives the periodic pulse from the delay time controller and outputs a first data signal earlier than the reference signal by a predetermined time.

Abstract: A digital broadcast receiving apparatus for receiving a broadcast signal generated by combining sub signals modulated using a random sequence generated based on an initial value set in accordance with a frequency of a broadcast channel by a signal transmission control use signal and a main signal generated based on information source data and reproducing the information source data contained in the received broadcast signal.

Abstract: A system and method is disclosed for evaluating a data group of oversampled bits to detect edge transitions and for improving use of information available from a sampled data while maintaining acceptable noise rejection. An edge detection system for receiving a serial data stream includes a sampler for collecting a sample pattern from the serial data stream, the sample pattern including a succession of a plurality of data samples from the data stream with the plurality of data samples including multiple samples during a bit time associated with the data stream; a memory, coupled to the sampler, for storing one or more successive sample patterns; and a correlator, coupled to the memory, for producing a sample condition signal using a set of predefined patterns by comparing the stored sampled patterns to the predefined patterns.

Abstract: The invention provides methods and apparatus for multiple user detection (MUD) processing that have application, for example, in improving the capacity CDMA and other wireless base stations. One aspect of the invention provides a multiprocessor, multiuser detection system for detecting user transmitted symbols in CDMA short-code spectrum waveforms. A first processing element generates a matrix (hereinafter, “gamma matrix”) that represents a correlation between a short-code associated with one user and those associated with one or more other users. A set of second processing elements generates, e.g., from the gamma matrix, a matrix (hereinafter, “R-matrix”) that represents cross-correlations among user waveforms based on their amplitudes and time lags. A third processing element produces estimates of the user transmitted symbols as a function of the R-matrix.

Abstract: System and method for performing symbol boundary aligned searches of signals. A preferred embodiment comprises a search control unit (such as search control unit 725) that can determine a start and stop condition for a correlation based on a hypothesis, a searcher (such as searcher 705) which includes a multiplexer that can select a subset of samples of a received sequence based on the hypothesis and start and stop conditions. The search control unit can then wait for the occurrence of the start condition and assign the hypothesis to a correlator, which will correlate the subset of samples with a locally generated pseudo-random number sequence based upon the hypothesis.

Abstract: A dynamic matched filter bank consists of a plurality of matched filters with either the reference signal for each matched filter changes with the time or the input signal to a matched filter is the received signal modified by a different way for a different matched filter. A receiver employed a set of dynamic matched filter banks in a multi-channel spread spectrum communication system consists of a signal register, a block PN generator, a plurality of spreading sequence generators, a plurality of register arrays, a plurality of multiplier arrays, a plurality of matched filters, a plurality of signal combiners, and a controller. The block PN generator generates a section of PN sequence at the end of every symbol period with feedback logic to shift a block of chips each time. A register array captures each section of PN sequence from the block PN generator and delays it for a symbol period. The rest register arrays are in cascade and delay the section of sequence at each of their inputs by one symbol period.

Abstract: A method of partial interference cancellation of a received signal that includes a first data component and a second data component is disclosed. The method includes the steps of determining a characteristic of the communication channel, estimating a factor based upon the characteristic, using the factor to cancel the second data component from the signal, and recovering the first data component from the signal.

Abstract: A method and apparatus for channel estimation in a spread spectrum receiver include processing that begins by despreading a received spread spectrum complex baseband sample utilizing a pseudorandom spreading sequence to produce a despread baseband symbol. The processing continues by filtering the despread baseband symbol to attenuate adverse channel effects based on a channel response estimate to produce a filtered despread baseband symbol. The processing then continues by decoding the filtered despread baseband symbol to produce recaptured data. The processing continues by modulating the recaptured data to produce a remodulated symbol. The processing then continues by producing a reconstructed spread spectrum complex baseband sample from the remodulated symbol based on the pseudorandom spreading sequence.

Abstract: A wireless receiver for receiving signals from an interference-limited transmitter in an interference-limited system comprising at least one transmit antenna, wherein the signals comprise a plurality of symbols. The receiver comprises a plurality of receive antennas and collection circuitry for collecting a plurality of signal samples with at least one symbol and interference effects. The receiver also comprises suppression circuitry, accumulation circuitry, circuitry for providing estimates of a group of bits, error detection circuitry and circuitry for requesting the transmitter to transmit a retransmission of a packet in response to detecting an error.

Abstract: Determination of the impulse position in a multipath channel in a noisy environment includes dynamically adjusting a threshold value when making comparisons against a signal property level.

Abstract: A multi-user detection method and device for a receiver in a multi-carrier code division multiple access telecommunication system, each communication to or from a user of the system being coded with a signature, the signal received by said receiver being decomposed into a first plurality of frequency components The frequency components are subjected to a first filtering matched to the respective signatures of a second plurality of users and to the common or respective responses of the transmission channels associated to said communications to or from said users. The output of the first filtering is subjected to a forward filtering followed by an estimation of the symbols transmitted to or by the users. The estimated symbols are subjected to a backward filtering, the output of said backward filtering being subtracted from the output of the forward filtering prior to the estimation.

Abstract: A structure of a spectrum spreading communication device which solves the problem with the conventional spectrum spreading communication using Barker codes, etc., and limits the rise of the side-lobe of a correctional signal independently of the order of information codes by use of a code sequence having a code length of at least 14. The spectrum spreading communication device uses a pseudo-noise code having code length of at least 14 and a self-correlation side-lobe of not greater than 3 as a pseudo-noise code of a direct spreading communication device which uses the pseudo-noise codes whose polarities are inverted so as to deal with also digital information. Thus, even when the pseudo-noise code length is 14 or more, the side-lobe of the correction coefficient can be restricted. Accordingly, the error rate of the spectrum spreading communication device is reduced and the processing gain is improved.

Abstract: A communication apparatus and method that includes generating a series of successive spread-spectrum signals formed through the concatenation of a direct sequence spread spectrum code with a Doppler Tolerant Polyphase Code (DTPC) is herein disclosed. By transmitting concatenated codes, it is possible to demodulate received sequences that are very long compared to the inverse of the Doppler frequency and/or the local oscillator drift. The method and apparatus may be applied to implement a wireless telecommunication system that efficiently transfers small quantities of data, such as status/telemetry, identification information and/or establishes device location at a low data rate over long distance in challenging radio environments and with low power consumption.

Abstract: Signal processing architectures for direct acquisition of spread spectrum signals using long codes. Techniques are described for achieving a high of parallelism, employing code matched filter banks and other hardware sharing. In one embodiment, upper and lower sidebands are treated as two independent signals with identical spreading codes. Cross-correlators, in preferred embodiments, are comprised of a one or more banks of CMFs for computing parallel short-time correlations (STCs) of received signal samples and replica code sequence samples, and a means for calculating the cross-correlation values utilizing discrete-time Fourier analysis of the computed STCs. One or more intermediate quantizers may optionally be disposed between the bank of code matched filters and the cross-correlation calculation means for reducing word-sizes of the STCs prior to Fourier analysis. The techniques described may be used with BOC modulated signals or with any signal having at least two distinct sidebands.