Abstract: The disclosed embodiments may relate to a method and apparatus for performing a correlation with respect to a received signal. A first correlator may correlate for a real part of a first characteristic of the received signal to produce a first real correlated signal. A second correlator may correlate for an imaginary part of the first characteristic of the received signal to produce a first imaginary correlated signal. A third correlator may correlate for a real part of a second characteristic of the received signal to produce a second real correlated signal. A fourth correlator may correlate for an imaginary part of the second characteristic of the received signal to produce a second imaginary correlated signal.

Abstract: An observation lock detector receives I and Q correlations and measurement residuals and transforms the I and Q quadrature correlation outputs based upon computed code phase and carrier phase into transformed I and Q quadrature signals communicated to conventional output lock detectors to provide validity and confidence indicator signals for indicating that the residual estimates are valid for dynamic propagation of the residuals in a navigation receiver for improved performance especially in low signal-to-noise environments such as for use in an ultratight GPS navigation system.

Abstract: A method for detecting a positioning signal includes (a) correlating a segment of a received positioning signal with a reference signal of a selected code phase and frequency to obtain a correlation value, (b) if the correlation value is less than a predetermined minimum, assigning the correlation value to the predetermined minimum, and (c) accumulating the correlation value in a sum of correlation values obtained using other segments of the received positioning signal. In addition, the correlation value may be reduced by a predetermined value, which is preferably an expected mean value for a noise component in the segment of the received positioning signal.

Abstract: An apparatus comprising: a first code controller for controlling the storage of a first spreading code portion; a first data input controller for controlling the storage of a first set of input samples; a second data input controller for controlling the storage of a second set of input samples; a combiner arranged to combine a spreading code sample with an input sample and output the resultant combination; a summer for summing said resultant combinations; and a combination controller arranged to control which of the stored first set of input samples or the stored second set of input samples provides said input sample for combination in the combiner.

Abstract: A method and apparatus for selecting a signal processing resolution. A received signal is processed using a first resolution. When a multipath condition is detected, the signal is processed using a second resolution.

Abstract: A method of correlating a digital communications signal is described. In an example, a window is defined equal to a portion of an epoch of the digital communication signal. The digital communication signal is then correlated across the window. A determination is made as to whether a correlation peak results from the correlating. Timing parameters are then established for receiving additional digital communication signals in response to presence of the correlation peak.

Abstract: A system and method for detecting a presence and frequency offset of a spread spectrum radio frequency signal is disclosed. The method comprises receiving the spread spectrum radio signal. The signal can be sampled to form a plurality of signal samples. Each signal sample can be multiplied by a complex conjugate of a proximate signal sample to form a plurality of signal sample pairs. The signal sample pairs can be summed over a predetermined dwell time period to form a data vector having a magnitude and angle offset to enable detection of the signal and to enable a frequency offset between the spread spectrum radio frequency signal and a receiver frequency reference to be determined.

Abstract: Implementation of an improved matched filter system for despreading a PN code from a spread spectrum signal utilizes a matched filter system that may be broadly conceptualized as a system that optimizes the number of multipliers and adders utilized by the system in despreading a PN code from a spread spectrum signal. This lowers the power consumption of the improved matched filter system and increases the speed at which the system despreads the PN code from the spread spectrum signal.

Abstract: Provided is a correlation apparatus based on symmetry of a correlation coefficient that can reduce complexity of hardware by reducing the number of adders and multipliers. Accordingly, when values of a real number part and an imaginary number part are exchanged with respect to a middle point of a correlation coefficient sequence and divided into two parts of left and right by the middle point of the correlation coefficient sequence, the values of the real number part and the imaginary number part are even-symmetrical with respect to the middle point of the divided two parts. Therefore, the number of the adders required for forming the correlation apparatus is reduced by at least 20% and the number of the multipliers is reduced by at least 70% in comparison with the 62 adders and the 64 multipliers required for a conventional correlation apparatus.

Abstract: A wireless communication system. The system comprises transmitter circuitry (BST1), the transmitter circuitry comprising encoder circuitry (50) for transmitting a plurality of frames (FR). Each of the plurality of frames comprises a primary synchronization code (PCS) and a secondary synchronization code (SSC). The encoder circuitry comprises of circuitry (501) for providing the primary synchronization code in response to a first sequence (32). The encoder circuitry further comprises circuitry (502) for providing the secondary synchronization code in response to a second sequence (54) and a third sequence (56). The second sequence is selected from a plurality of sequences. Each of the plurality of sequences is orthogonal with respect to all other sequences in the plurality of sequences. The third sequence comprises a subset of bits from the first sequence.

Abstract: A disclosed power level measuring device includes a power calculator for calculating power values based on correlation values between a received signal and known signals, for each of sampling times within a predetermined period; a time divider for switching connection of input signals, responding to time slots allocated to each of plural cells; an accumulator connected to the time divider, for accumulating the power values; a detector for detecting at least one sampling time whose accumulated value is greater than a threshold; a memory connected to the time divider, for storing the power values; and an outputting unit for outputting a measured power level, based on the stored power value corresponding to the detected sampling time.

Abstract: Embodiments of an adaptive in-phase (I) and/or quadrature-phase (Q) imbalance correction for multicarrier wireless communication systems is generally described.

Abstract: A surface acoustic wave (SAW) expander based transmitter and correlator based receiver comprises SAW devices that perform expander or correlator functions based on the types of signals inputted to the SAW devices. The SAW devices incorporate chirp with adaptive interference and programmable coding capabilities. The SAW devices and method of operating the devices allow the implementation of very low power radios that overcome problems with temperature drift, lithography constraints and interference and jamming suffered by prior art implementations.

Abstract: A device for detecting a correlation maximum value from a sequence of correlation magnitude values includes a means for determining a reference value from correlation magnitude values within an interval of the sequence of correlation magnitude values, the correlation magnitude value to be assessed lying external to interval. A means for determining a threshold value provides the threshold value in dependence on the reference value. A means for comparing the correlation magnitude value to be assessed with the threshold value ascertained for the correlation magnitude value to be assessed is configured to provide, depending on the comparison result, a trigger signal which indicates whether a correlation magnitude value to be assessed is a correlation maximum value.

Abstract: Wireless communication receiver with hybrid equalizer and RAKE receiver. The receiver compares performance of the system for RAKE only and RAKE in combination with equalizer estimates. The receiver enables or disables the equalizer accordingly.

Abstract: A method and apparatus for detecting a spread spectrum signal is described. Signals can be detected using correlation techniques. When a signal is detected, declaring of signal presence is inhibited for offsets of signal parameters from the parameters of the detected signal, where the offset corresponds to a known sidelobe of the spreading code. This helps to reduce false detections caused by sidelobes of the spreading code.

Abstract: A system provides for remote monitoring using asynchronous code division multiple access (CDMA) communication techniques between a base station and one or more transponders. Each transponder is attached or otherwise associated with an object or an environment to be monitored. Upon receipt of an interrogation signal, a transponder generates and transmits a coded transponder signal containing the monitored data. The coded transponder signal is generated using a spreading code. Each transponder is associated with a unique, mutually exclusive set of spreading codes. Each spreading code is based on a unique transponder address and the monitored data to be sent. A detector asynchronously monitors received signals for any of the available spreading codes. Once the detector detects a particular spreading code, the base station can identify the source transponder and extract the monitored data.

Abstract: A low cost method and system for efficiently implementing channel estimation in a wireless communication system using any desired length of a fast Fourier transform (FFT) independent of burst type or signal structure. The hardware complexity required to perform the channel estimation to process a plurality of different burst types is reduced. Simple tail zero-padding is used when the length of FFT is extended to a desired length for more efficient computation.

Abstract: A technique for determining the time of arrival of a signal includes generating a spread spectrum signal with a number of code sectors, each including a periodic sequence of spread spectrum chips that corresponds to a predetermined correlation function. The periodic sequences of chips of the code sectors are shifted in time by differing amounts relative to a periodic time reference. Upon reception, the spread spectrum signal is periodically sampled, and the different code sectors produce different sampling points on the correlation function such that a number of time-shifted correlation functions results from time shifts of the code sectors. The time of arrival of the spread spectrum signal can be determined by curve fitting of the sampling points from the set of time-shifted correlation functions.

Abstract: A technique for receiving an error state in a single chip sequence in a wireless communications network is disclosed. The error state may comprise a Viterbi error state. The error state may be identified as a target code encoded in the single chip sequence, the target code comprising either a code or the complement of the code. The code may comprise a PN-Code. The error state may be identified using a previous mapping of error states from a set of error states to a group of codes, the group of codes comprising a plurality of codes and their complements. The error states in the set of error states in the previous mapping may be uniquely mapped to plurality of codes and their complements in the group of codes.

Abstract: The present invention discloses a method for detecting orthogonal code CDMA signal implemented mainly through the following steps: estimating the total power of interference to the multi-path signals; performing matched filtering on the multi-path signals and performing maximum ratio combining on the multi-path signals by utilizing the total power of interference to the multi-path signals, to obtain the optimized matched filtering result; and performing joint detection on the optimized matched filtering result. There are two schemes for implementing: if the optimized matched filtering detection scheme is used, only the first two main steps are executed; if the joint detection scheme is used, all of the three steps are executed. In either of above two schemes, the interference code channels involved in the estimation of total power of interference to the multi-path signals are need to be selected, i.e.

Abstract: Systems (400, 500, 600) and methods (300) for generating a chaotic amplitude modulated signal absent of cyclostationary features by preserving a constant variance. The methods involve: generating a PAM signal including pulse amplitude modulation having a periodically changing amplitude; generating a first part of a constant power envelope signal (FPCPES) by dividing the PAM signal by a square root of a magnitude of the PAM signal; generating a second part of the constant power envelope signal (SPCPES) having a magnitude equal to a square root of one minus the magnitude of the PAM signal; and generating first and second spreading sequences (FSS and SSS). The methods also involve combining the FPCPES with the FSS to generate a first product signal (FPS) and combining the SPCPES with the SSS to generate a second product signal (SPS). A constant power envelope signal is generated using the FPS and SPS.

Abstract: A method for determining the occupancy of a transmission channel using a differentially demodulated signal generated at a transmitter-side with the use of PN sequences from a PN sequence set having a first group of first PN sequences and a second group of second PN sequences. The method provides a) at least two subsequences of an initial code sequence, which is assigned to one of the first PN sequences and can be derived from the sequence by logical operations, but is not identical to it, b) the calculation of at least two correlation results by correlating the differentially demodulated signal with each of the at least two subsequences, and c) the evaluation of the correlation results and generation of an output signal to indicate the occupancy of the transmission channel. Also a device for determining the occupancy of a transmission channel.

Abstract: Establishing slot boundaries includes receiving a feedback signal reflecting feedback information describing a signal modified according to a diversity parameter adjustment. The feedback signal includes slots and bits. A slot boundary is established for each of the slots by: partitioning the bits into periods; comparing the bits of each period; and establishing the slot boundaries in accordance with the comparison.

Abstract: The invention relates to a system and a method of digital communication between synchronized submarine devices, system including means of sending a signal in modulated bit form, at least one sender (100) and at least one receiver (200), characterized in that said at least one sender (100) sends a signal enabling both any data to be transmitted to said at least one receiver (200) and a propagation time between said at least one sender (100) and said at least one receiver (200) to be measured.

Abstract: A Node-B/base station has an access burst detector. The access burst detector comprises at least one antenna for receiving signals from users and a pool of reconfigurable correlators. Each correlator correlates an inputted access burst code at an inputted code phase with an inputted antenna output. An antenna controller selectively couples any output of the at least one antenna to an input of any of the correlators. A code controller provides to an input of each correlator an access burst code. The code controller controls the inputted code phase of each controller. A sorter/post processor sorts output energy levels of the correlators.

Abstract: A symbol detector for an OFDM receiver determines the correlation of corresponding samples of at least two received preamble symbol samples, one of the samples delayed a predetermined duration with respect to the other; determines a timing metric based on the correlation results; detects multiple peaks in the timing metric; indicates a symbol detection based on the multiple peaks detected in the timing metric; and gets a refined CFO estimation using averaging the phase information across these multiple peaks.

Abstract: An apparatus and a method for tracking a sampling clock of a multi-carrier communication system are disclosed, the apparatus including a data removal module, a phase estimation module, and a sampling clock offset computation module. The data removal module is for generating a plurality of first and second data removal symbols by removing predetermined transmitted data from a plurality of first and second received symbols, respectively. The phase estimation module for generating a first and a second phase shifts according to correlations of the plurality of first and second data removal symbols. The sampling clock offset computation module for generating a control signal utilized to compensate the sampling clock of a plurality of received symbols according to the first and a second phase shifts.

Abstract: Provided are an initial synchronization acquiring device and method in a parallel processed DS-CDMA UWB system and a DS-CDMA UWB system's receiver using the same. The initial synchronization acquiring device is constructed to include a correlator for correlating input signals and outputting correlation result values and an initial synchronizer for tuning initial symbol synchronization and frame synchronization by using the correlation result values received from the correlator and then storing combining mark values and a synchronization position value in a register, thereby making it possible to greatly decrease a system's complexity, compared to the existing method of separately designing respective modules for acquiring packet synchronization and symbol synchronization in the existing CDMA system.

Abstract: Demodulator architectures for processing a received signal in a wireless communications system. The demodulator includes a number of correlators coupled to a combiner. Each correlator typically receives and despreads input samples (which are generated from the received signal) with a respective despreading sequence to provide despread samples. Each correlator then decovers the despread samples to provide decovered “half-symbols” and further demodulates the decovered half-symbols with pilot estimates to generate correlated symbols. The decovering is performed with a Walsh symbol having a length (T) that is half the length (2T) of a Walsh symbol used to cover the data symbols in the transmitted signal. The combiner selectively combines correlated symbols from the assigned correlators to provide demodulated symbols. One or more correlators can be assigned to process one or more instances of each transmitted signal.

Abstract: A baseband processing module according to the present invention includes a multi-path scanner module. The multi-path scanner module is operable to receive timing and scrambling code information regarding an expected multi-path signal component of a WCDMA signal. Then, the multi-path scanner module is operable to identify a plurality of multi-path signal components of the WCDMA signal by descrambling, despreading and correlating a known symbol pattern of/with a baseband RX signal within a search window. The multi-path scanner module is operable to determine timing information for the plurality of multi-path signal components of the WCDMA signal found within the search window and to pass this information to a coupled rake receiver combiner module.

Abstract: A method for estimating the speed of a mobile device in a network is provided that includes selecting a correlation length from a plurality of possible correlation lengths. A correlation result is generated based on the selected correlation length. A speed estimate is generated for the mobile device based on the correlation result.

Abstract: A system for determining the burst start timing of a signal includes logic configured to receive the signal, generate correlation moduli and generate a first timing output based on the correlation moduli. The logic may also be configured to receive operating mode information and timing information and generate search controls. The logic may further be configured to identify a maximum of the correlation moduli using the search controls and determine a second timing output associated with the maximum correlation modulus. The second timing output represents a more accurate approximation of a burst start time than the first timing output.

Abstract: A method for estimating signal quality of a spread spectrum signal is provided. The method includes squaring a plurality of in-phase correlation results and a plurality of quadrature correlation results, summing each squared in-phase correlation result and the corresponding correlation result to obtain a plurality of sum-of-square values, detecting a peak value among the plurality of sum-of-square results, calculating an average of non-peak values among the plurality of sum-of-square results. The peak value is regarded as a signal power value, while the averaged non-peak values are regarded as an average noise power value. A signal-to-noise ratio is then calculated based on the signal power value and the average noise power value. A method for determining the parameters for the tracking loop is also provided. The method includes estimating the signal-to-noise ratio of the spread spectrum signal, and determining the tracking loop parameters based on the signal-to-noise ratio.

Abstract: A single, common correlation filter (CF) core is provided in a receiver for recovery of data from received code division multiple access (CDMA) signals. Signals are received over CDMA channels with different data rates, where the received signals include user information such as pilot and data symbols that have been spread according to different despreading rates including tier 1, tier 2 and tier 3 rates, where tier 1 is the smallest despreading rate. The received signal is correlated at the smallest despreading rate in the correlation filter (CF) by time multiplexing delayed versions of the pseudorandom noise (PN) code. The correlated information is then demultiplexed and pilot-aided QPSK demodulated. The demodulated information is summed at the proper integer multiple of the tier 1 rate to achieve tier 2 and tier 3 despreading rates. According to an embodiment, the three strongest multipaths components in terms of the received power are selected in a window or time period for optimal information recovery.

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 parallel correlator and method includes temporarily storing in a series of P sequence registers, each of length R1, serial bit-sequences of a code of length N=P*R1. In a first-level of processing, certain unique bit sequences are inverted to reduce the number of unique bit sequences by half. Identical bit-sequences are then combined and temporarily stored in a first-level sub-accumulation register. Alternatively, bit sequences differing by only one bit may be combined in a common first-level sub-accumulation register. Further levels of similar processing may be imposed, where each subsequent level taps and inverts only a portion of the bits in the above level of processing, thereby reducing the number of unique bit sequences. Finally, all negative energy is combined in one register position, inverted, and added to all positive energy in the other register positions.

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 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: Frequency translation and spread spectrum applications of same are described herein. Such applications include, but are not limited to, unified down-conversion and de-spreading, unified up-conversion and spreading, RAKE receivers utilizing unified down-conversion and de-spreading, and Early/Late receivers utilizing unified down-conversion and de-spreading, and combinations and applications of same. Additionally, applications are included for limiting spectral growth during unified up-conversion and spreading of a baseband signal.

Abstract: A method and apparatus is disclosed for reducing multi-user processing at the receiver in wireless communication systems. Detected codes are grouped according to channel impulse response and a parent code is identified for each group of detected codes. A matrix A is constructed and joint detection is performed using the identified parent codes. Data symbols of the detected codes are obtained from the data symbols of the identified parent codes.

Abstract: A system and method suppresses the interference caused by non-orthogonal signals on multiple channels of the same receiver by applying an inverse of the correlation among the non-orthogonal signals to the decoded signals. In a multi-channel receiver, the receiver is aware of the codes that are allocated to each of the channels, and thus, can be configured to determine the correlation among the multiple codes that are allocated to a receiver. The inverse of this correlation is applied to the output of the correlators assigned to each code, thereby suppressing the effects of using non-orthogonal codes for transmissions to the same receiver. If different sized codes are allocated to the same receiver, the correlation of the shorter code and a corresponding segment of the longer code is computed. The inverse of the correlation for the segment is applied to the output of the correlators, corresponding in time to the processing of the shorter code and this segment of the longer code.

Abstract: A diversity receiving apparatus receives first and second reception signals and is constituted by including one or more phase shifters that generate one or more third signals having phases different from the second reception signal based on the second reception signal, a correlation calculator that obtains a correlation between the first reception signal and each of the second reception signal and the third reception signals, a correlation comparator that selects the reception signal having the highest correlation with the first reception signal from the second reception signal and the third reception signals, a selector that selects and outputs the second reception signal or the third reception signal selected by the correlation comparator; and a combining device that outputs a signal formed by combining the first reception signal and the reception signal output from the selector.

Abstract: The invention is related to a network element, comprising: means for receiving feedback information from the user device; means for creating a first orthogonality measure by using the feedback information; means for creating a second orthogonality measure by comparing transmission resources; means for transmitting information to at least one user device.

Abstract: A receiving system allows for the coherent detection of a spread-spectrum transmission at any point in time during the transmission, thereby avoiding the need to identify the start of the transmission during the transmission-detection process. An input buffer captures the transmissions on a communication channel using a moving time-window. A detector processes a time-slice from the input buffer and identifies all of the simultaneously transmitting transmitters during that time-slice. As each transmitter is identified, the demodulator traces back-in-time to identify where the message can first be detected in the input buffer. The transmission includes suitable characteristics to facilitate detection and demodulation of the message content, but need not contain a preamble to allow the detection process.

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: An initial ranging detection for an orthogonal frequency division multiple access (OFDMA) wireless communication system entails removing data sub-carriers from samples of an OFDMA signal in order to suppress inter-carrier interference (ICI) between the data sub-carriers and initial ranging sub-carriers, coherently summing the resulting samples to boost signal energy, and applying a sliding window FFT to the coherently summed samples for correlating each result of the sliding window FFT with each one of a set of predetermined codes. The suppression of ICI is done by removing the cyclic prefix, performing an FFT to transform to the frequency domain whereupon the initial ranging sub-carriers are zeroed. An IFFT is then performed to return to the time domain. The cyclic prefix is then added and the new samples are subtracted from the originally received samples. The resulting samples are free of ICI and can then be coherently summed to boost signal energy.

Abstract: A Direct-Sequence Code Division Multiple Access (DS-CDMA) receiver and method of allocating probing correlators and combining correlators (fingers). A front-end processor converts received radio signals to baseband samples. Based on average path strengths, a controller adaptively allocates probing correlators to signal paths to de-spread certain received signals. Based on path power estimates, the controller adaptively allocates combining correlators to signal paths. The allocations may be made to minimize the total received power at the receiver, or to achieve acceptable performance for all users.

Abstract: An apparatus and method for tracking a sampling clock are disclosed. The apparatus includes a compensating circuit compensating phases of a first and a second received symbols according to a compensating signal and thereby generating a first and a second compensated symbols; a data removal circuit removing a first predetermined transmitted data from the first compensated symbol, and a second predetermined transmitted data from the second compensated symbol and thereby generating a first and a second data removal symbols; and a computing circuit generating a sampling clock offset according to the first and the second data removal symbols, and adjusting the sampling clock signal according to the sampling clock offset.

Abstract: A wireless communication method and system for assigning multi-paths to Rake receiver fingers. A Rake finger assignment database is established in which multi-path signals are categorized into a verified group and an unverified group. Each multi-path is assigned to an individual bin in the database. Each bin includes a pilot phase data field, an antenna data field, a code data field, an averaged signal strength data field, an assigned flag data field, a verification flag data field, an update flag data field, an assigned Rake finger number data field and an assignment time counter data field. The multi-path signals in the verified group are further categorized into an assigned subgroup and an unassigned subgroup. During a measurement interval, each of a plurality of newly measured multi-path signals is compared to the multi-path signals in the database and is processed accordingly.