Abstract: Systems and methods for refining the determination of the time of arrival (TOA) of given data. A portion of packet data is designated to be used as a pseudo TOA sequence. The packet information is modulated using, e.g., BPSK, and thereafter spread with a chipping stream known at both source and destination radios. The resulting stream includes a TOA reference pattern. On the receive side (destination radio), receive samples are despread and demodulated. The despread data is then XOR'ed with the chipping stream to re-create the TOA reference pattern. The re-created TOA reference pattern and original receive samples (previously stored) are passed through a correlator to obtain a correlation profile, which is then used for curve fitting/interpolation to accurately determine the TOA of the given received sample. Embodiments may be used in conjunction with a radio ranging system.

Abstract: In a mobile communication system, multiple transceivers perform radio communications in the same frequency band.

Abstract: A set of piconets and corresponding methods and computer programs may reduce contention time between piconets. In one embodiment, a seven-length code architecture may be used with group(s) of bands so that contention time cannot exceed 1/7 of the time. Up to seven different bands can be used within each group. When less than seven bands are used (e.g., three or six), at least one of the bands may be assigned to more than one dwell time during a time span. Alternatively, each dwell time within the time span may be assigned to a different band. The state may be changed as needed or desired. Substitution of extra bands may also be used. Using either scheme (repeated bands or changing states), a prime-number architecture can be used with a non-prime number of different bands. Simultaneous communications using at least two bands within a piconet may be used.

Abstract: Performing approximate diagonalization of a correlation metric by user permutation to improve Multiuser Detector (MUD) processing. The system reorders the entries in the S-Matrix in order to move the bit decisions closer together in the decision tree. In one embodiment the reordering is a sequential pairwise correlation.

Abstract: An apparatus and method for adjusting transmission phasing in a point-to-point communication link is disclosed. The relative phases of the transmissions from each antenna are adjusted before transmission to give optimum gain when received by two or more antenna elements and a signal combining element. The signal includes a data component, consisting of a subset of the subcarriers modulated with the input data, which is common to transmissions from all antenna elements; and a phase reference component consisting of a subset of the subcarriers that are modulated with a predetermined phase. The signal combining element is operable to receive the components and extract phase information.

Abstract: A method of performing cell search includes receiving a primary synchronization signal (PSS) comprising a primary synchronization code (PSC) and receiving a secondary synchronization signal (SSS) comprising a first secondary synchronization code (SSC) and a second SSC, wherein the SSS includes a first SSS and a second SSS, the first SSC and the second SSC are arranged in that order in the first SSS, and the second SSC and the first SSC are arranged in that order in the second SSS. Detection performance on synchronization signals can be improved, and cell search can be performed more reliably.

Abstract: Methods and apparatuses for establishing time at a first basestation, and synchronizing the first basestation with other basestations in a cellular network. The method may be performed using a mobile (cellular communication) station that includes a satellite position system receiver. One method comprises determining a location of the mobile station, determining a time indicator that represents a time-of-day at the mobile station, wherein the time indicator is determined relative to a signal available at the first basestation, transmitting at least one of the position information and location, and transmitting the time indicator from the mobile station. The time indicator and at least one of the position information and the location are used to establish a time at the first basestation such that the first basestation is synchronized to other basestations in the cellular communication system. Other methods and apparatuses are also described for synchronizing basestations in a cellular network.

Abstract: A synchronization timing detecting apparatus includes a correlation calculator configured to generate a first correlation value by calculating a cross-correlation between an input signal being sampled and a reference signal or an auto-correlation of the sampled input signal, an interpolation processor configured to generate a second correlation value interpolating a plurality of the first correlation values having a different combination of sampling points of the input signal, and a detector to detect a synchronization timing based on the first and the second correlation values.

Abstract: A time domain symbol timing synchronization circuit is disclosed, which comprises: an autocorrelation function calculator for calculating cyclic prefix autocorrelation functions and an offset time estimator for searching peak positions of cyclic prefix autocorrelation functions to indicate symbol boundary of received communication symbols. The offset time estimator compares a current peak position and a previous peak position. If (a) the difference of the positions is larger than a threshold and (b) the current peak is smaller than a reference average peak, the current peak is determined as false; the offset time estimator weeds out and replaces the current peak position by the previous peak position; and the current peak is not introduced in the reference average peak calculation.

Abstract: A method is provided for receiving a data frame in an ultrawide bandwidth network. In this method, a device receives an ultrawide bandwidth signal containing a data frame. The device then performs an acquisition operation during a first preamble in the data frame, and identifies a marker after the first preamble that indicates that the first preamble has ended. After this, the device performs a signal processing operation during a second preamble in the data frame. After the training, the device then receives a header in the data frame, and then receives a payload in the data frame. By having a marker between the two preambles, this method provides a receiving device with critical information regarding the timing of the preamble section of a frame.

Abstract: A pseudo noise code (PN code) tracking circuit includes a first correlator, a storage device, a second correlator and a detector. The first correlator is utilized for performing correlation on a first PN code in a first signal frame with a local PN code to generate a first set of correlation values, and for performing correlation on a second PN code in a second signal frame with the local PN code to generate a second set of correlation values. The storage device is coupled to the first correlator for storing the first and second sets of correlation values. The second correlator is coupled to the storage device for performing correlation on the first set of correlation values with the second set of correlation values to generate a shift value. The detector is coupled to the second correlator for generating a frame number according to the shift value.

Abstract: An apparatus (200) and method (300) for receiving a communications signal. A spread spectrum signal demodulator (210) is adapted to demodulate a packet header (110) of a data packet (102) that is communicated by a wireless communications signal. The packet header (110) is modulated with a spread spectrum technique and the spread spectrum signal demodulator (210) produces a packet header detection signal (220) representing a successful detection of a predefined packet header value. A non-spread spectrum signal demodulator (212) is communicatively coupled to the spread spectrum signal demodulator (210) and demodulates, in response to the packet header detection signal (220), a non-spread spectrum modulated data payload within the data packet. A data output select (234) produces demodulated data produced by either one or both the spread spectrum signal demodulator (210) and the non-spread spectrum signal demodulator (212).

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 random access apparatus for supporting a variety of access service classes includes a radio frequency (RF) transmitting/receiving unit for receiving a preamble introduction broadcasting signal from a base station and transmitting a random access preamble to the base station, an introduction broadcasting signal processing unit for extracting a random access usage relating to M-sequences and hadamard sequences from the received preamble introduction broadcasting signal, a selecting unit for selecting a plurality of M-sequences and a hadamard sequence corresponding to a random access purpose based on the extracted random access usage, and a preamble producing unit for generating the random access preamble using the selected plurality of M-sequences and the selected hadamard sequence.

Abstract: Disclosed is an apparatus and method for estimating a start point of a frame in a wireless communication system. The method includes the steps of receiving a frame and estimating the start of the frame by searching for an interval or point of time during or at which a correlation between preambles is at its maximum. At this time, to in order to estimate the start of the frame, a cyclic prefix is used. Thus, a correlation between a cyclic prefix and the last interval of a symbol, which is the same as the cyclic prefix, is calculated and an interval or point of time having the maximum correlation is estimated as the start point of the cyclic prefix. Therefore, the start point of the frame can be accurately estimated based on the start point of the cyclic prefix.

Abstract: A device and method for predicting noise in a signal that is received by a digital receiver is provided. The device includes an autocorrelation function determination device and a noise predictor device. Also included in the device is an adaptive filter that produces a prediction error value for the received signal and the adaptive filter adjusts the filter coefficients as a function of a prediction error of the adaptive filter. Using the filter coefficient of the adaptive filter, the method may determine the autocorrelation function of the received signal. The noise estimated values for the noise contained in the received signal may be computed on a basis of the autocorrelation function of the received signal. The embodiment also may facilitate noise prediction when heavy correlated noise is present.

Abstract: A spread spectrum signal having an associated code is tracked at a receiver. A plurality of components of the spread spectrum signal are despread using the associated code. Each of the plurality of components has a different code phase than all others of the plurality of code phases. Each of the plurality of components is weighted based on a phase difference between that component and a center code phase associated with the plurality of components. A tracking error is determined based on the weighted components.

Abstract: In a cellular network, a GPS receiver includes circuitry that modulates a global positioning system (GPS) timing pulse signal with a carrier signal and transmits the modulated signal to one or more remote base stations. When the modulated timing pulse signal is received at a remote base station it is demodulated and a timing pulse signal corresponding to the GPS timing pulse signal is recovered. The remote base station may be configured to transmit a reply signal back to the GPS receiver, which can then be used to estimate a propagation delay between the GPS receiver and the remote base station.

Abstract: Described is a system and method related to the synchronization of a communication stream between two devices. A broadcast signal is a segmented information signal that includes a distributed synchronization pattern and a distributed frame index. Each segment of the segmented information signal further includes a header portion and a payload portion. The header portion of the segmented information signal includes a portion of the distributed synchronization pattern and a portion of the distributed frame index. The method includes generating the distributed synchronization pattern and the distributed frame index, distributing the synchronization pattern and frame index throughout the signal, and transmitting the signal.

Abstract: The present invention provides systems and methods for pseudo-random signal generation in a multi-carrier communications system. In embodiments, a transmitter includes a pseudo-random bit sequence (PRBS) generator and Medley signal generator. The PRBS generator can operate in at least one of the following modes: a parameter selection mode, a scrambler mode, and/or a combination mode. The Medley signal generator receives an output bit sequence from the PRBS generator. The Medley signal generator then generates a Medley signal which includes a set of Medley tones encoded based on the output bit sequence from the PRBS generator. The Medley signal is then sent over channels of a multi-carrier communication system such as an ADSL system.

Abstract: A phase conjugation vectoring (PCV) of signals propagating in telephone cables of twisted pairs provides crosstalk free transmission therethrough. The cable is considered a non-uniform physical media, and criteria for phase conjugation of electromagnetic fields are established. Method and system provide PCV for both asymmetric and symmetric transmission.

Abstract: Described is a system and method for providing a synchronization pattern in a communication system. The method includes generating a synchronization pattern with good randomness properties; packing a signal for transmission with m headers, each header consisting of the synchronization pattern 1/m symbol-time shifted from the previous header; and transmitting the signal. A further method provides for the sampling the transmitted signal with m headers of symbol-time shifted synchronization patterns; and determining symbol timing offset by computing and reordering correlation peaks from the synchronization patterns. A system includes a transmitting system, a receiving system, and a data channel. The transmitted signal includes m headers with 1/m symbol-time shifted synchronization patterns. The receiving system undersamples the transmitted signal with m synchronization patterns to simulate an oversampled synchronization pattern.

Abstract: A set of piconets and corresponding methods and computer programs may reduce contention time between piconets. In one embodiment, a seven-length code architecture may be used with group(s) of bands so that contention time cannot exceed 1/7 of the time. Up to seven different bands can be used within each group. When less than seven bands are used (e.g., three or six), at least one of the bands may be assigned to more than one dwell time during a time span. Alternatively, each dwell time within the time span may be assigned to a different band. The state may be changed as needed or desired. Substitution of extra bands may also be used. Using either scheme (repeated bands or changing states), a prime-number architecture can be used with a non-prime number of different bands. Simultaneous communications using at least two bands within a piconet may be used.

Abstract: A correlation system for Time Division Multiple Access (TDMA) positioning systems is disclosed, whereby a position receiver acquires, tracks, and demodulates a plurality of Code Division Multiple Access (CDMA) modulated positioning signals are pulsed in a Time Division Multiple Access (TDMA) scheme. A specialized correlation processor within the position receiver is configured to internally generate pseudo-random number (PRN) code signal replicas of Code Division Multiple Access (CDMA) positioning signals in synchronicity with their respectively received Time Division Multiple Access (TDMA) positioning signals. This correlation system provides the position receiver with range measurements free from the deleterious effects of Code Division Multiple Access (CDMA) cross-correlation artifacts and degraded signal-to-noise ratios, therefore allowing the computation of high accuracy position solutions.

Abstract: An uplink signal transmitted by a terminal is received by a satellite wireless communications system. The uplink signal includes a known information element, e.g., a reverse access channel (R-ACH) preamble, spread according to a spreading code specific to a component of a satellite wireless communications system, e.g., a pseudonoise (PN) sequence associated with a satellite beam. A correlation of the received uplink signal with the spreading code over a range of time shifts is determined. The known information element is detected from the determined correlation. The satellite wireless communications system is synchronized with the terminal responsive to detection of the known information element. For example, a delay may be assigned to a receiver of the satellite wireless communications system responsive to detection of the known information element.

Abstract: A multi-mode transmitter (301) is adapted to modulate a data packet (200) communicated by a wireless communications signal. The data packet includes a packet header comprising a preamble (201) and a start of frame delimiter (202), and a data payload comprising a payload data length portion (203) and a payload portion (204). The packet header is modulated with a spread spectrum technique. When transmitting a data payload in one mode, the data payload is also modulated with the spread spectrum technique. When transmitting a data payload in another mode, the data payload is modulated with a non-spread spectrum technique.

Abstract: A timing correction system for fast PN acquisition is provided. The system includes a signal sampler for testing any incoming signal and a real-time clocker coupled to the signal sampler. A parallel correlator is coupled to the real-time clocker for searching for a PN sequence and a burst detector is coupled to the parallel correlator. A chip timing corrector is coupled to the burst detector and a processor is coupled to the chip timing corrector for determining signal timing.

Abstract: A method and system for frame synchronization in a digital data transmission. A synchronization word is selected that is suitable for good correlation in a receiver detector. Either traffic bits or control bits are interleaved within the synchronization word in a predetermined pattern that is fixed for consecutive frames. The position of the sync word is varied from frame-to-frame. Also, the interleaved bits that are either traffic or control bits varies substantially between consecutive frames.

Abstract: Collisions between messages simultaneously transmitted by multiple spread-spectrum transmitters are reduced by distributing the transmissions over the available resources of the receiver. Each mobile station in a CDMA system uses one or more randomization methods to distribute its transmissions. In the first randomization, the mobile station time-delays its transmissions by a number of chips of the PN code with which it spreads the transmitted signal. In a second randomization, the mobile station randomly selects the PN code. In a third randomization, the mobile station inserts a random delay between successive message transmissions or probes if it does not receive an acknowledgement after a predetermined timeout period. A predetermined number of such transmissions is called a probe sequence. In a fourth randomization, the mobile station inserts a relatively long random delay between successive probe sequences if it does not receive an acknowledgement of any probe in the sequence.

Abstract: A method for generating a preamble sequence in an orthogonal frequency division multiplexing (OFDM) communication system having A subcarriers in a frequency domain. The method comprises generating a length -M×N preamble sequence, where M×N is less than A, by using a length-N Golay complementary sequence and a length-M Golay complementary sequence; and assigning elements constituting the preamble sequence to M×N subcarriers among the A subcarriers on a one-to-one mapping basis, assigning null data to the remaining subcarriers excluding the M×N subcarriers from the A subcarriers, and then IFFT-transforming the assigned result into time-domain data.

Abstract: An apparatus and method are disclosed for acquiring by a mobile terminal a pseudo-random noise (PN) sequence of a pilot signal received from a base station by means of a searcher, designating a phase of the acquired PN sequence as a reference phase to track the phase of the acquired PN sequence, and measuring an energy difference between an early path and a late path for the reference phase in a mobile communication system. In the apparatus and method, a first energy measurer measures a first energy value from a PN sequence with the reference phase, and a second energy measurer alternately measures energy values of the early path and the late path for the reference phase and outputs a second energy value.

Abstract: A transmitter employing a cryptographic algorithm and key generates and transmits a staggered pulse signal that includes a plurality of high-power pulses that are part of a pseudonoise (PN) code. The high-power pulses are separated by a group of low-power chips and the time interval between the high-power pulses is varied according to the cryptographic algorithm and key. A receiver, employing a corresponding cryptographic algorithm and key receives the signal and correlates it with a locally generated code that is modified according to the cryptographic algorithm and key to detect the phase of the received PN code. The receiver also can include a matched filter configured according to the cryptographic algorithm and key to detect the sequence of high-power pulses in the received signal.

Abstract: A channel sounding system employs orthogonal sequences to meet the Cramer-Rao bound in estimating the channel and achieves considerable simplification of the structure necessary to perform the channel sounding. These advantages are achieved by developing orthogonal sequences of substantially arbitrary length as a function of first and second existing orthogonal sequences and using such orthogonal sequences for channel sounding in lieu of M-sequences. The techniques of the invention are especially suited to systems that use multiple antennas at the transmitter and multiple antennas at the receiver, so called multiple-input multiple-output (MIMO) systems.

Abstract: There is provided a PN (Pseudorandom Noise) hypothesis moving apparatus and method in a high speed searcher. In the PN hypothesis moving apparatus, a PN sequence generator system has a PN sequence generator for generating a PN sequence and a PN state register for storing information about a PN state. A correlation counter counts the number of correlations, and a comparator receives the output of the correlation counter, a correlation length, and a search speed, compares them, and provides a PN state saving point and a PN state loading point to the PN sequence generator system according to the comparison to change a PN hypothesis.

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: A method is described for determining a time offset of a CDMA signal incurred during transfer. For each of a plurality of time offset estimates, the received chip sequence is multiplied with a conjugate complex scrambling code that is shifted by a number of chips according to one of the time offset estimates; the chip sequence is despreaded based on a spreading code of at least one selected data channel to produce a symbol sequence, and an estimated amplification factor is determined by summation of an amount of the symbol sequence. The maximum of the amplification factors for the time offset estimates when a selected data channel is active, or the minimum of the amplification factors for the time offset estimates when the selected data channel is not active is then determined.

Abstract: A method of controlling timing for an uplink synchronous transmission scheme is disclosed, including combining time alignment bit (TAB) information transmitted received during a predetermined period, determining a timing renewal value based on the combination, and controlling the transmission timing according to the timing renewal value. Thus, the TAB information transmitted by a base station may be used to synchronize the uplink transmissions of mobile communication devices.

Abstract: A generator of repetitive sets of spreading sequences comprising element (20), for counting and for forming an address and a table (30) containing L sets of S sequences, wherein the address contains q=1+log2S bits, in which one set among L (L=2q) sets is selected and wherein the log2S bits select one sequence among the S sequences in the set.

Abstract: A mobile wireless communications device and methods therefore, including receiving a signal (710), storing a portion of the received signal (730), identifying all possible pilot signals by determining slot boundary information for the stored signal portion (720), determining frame boundary information and/or scrambling code information (760) of the stored signal portion by correlating the stored signal portion with the scrambling codes based on the slot boundary information. In other embodiments, the search is performed in real-time without storing the signal.

Abstract: A method and system for synchronizing the PN phase of a pseudo-noise (PN) coded signal with a phase of a master PN decade-code is provided. The method includes the steps of associating the master PN decade-code initialization t0 with a first time zone reference date and time and determining an elapsed time t1. The next steps equate the elapsed time t1 to a corresponding phase of the master PN code and synchronize the phase of the PN coded signal with the corresponding phase of the master PN decade-code.

Abstract: An apparatus and method for acquiring multi-user signal synchronization in a CDMA system is disclosed. In a preferred embodiment, pilot signals are generated using different PN seeds and the generated pilot signals are aligned to thus be transmitted within a predetermined time from the synchronization point of time in a plurality of CDMA transmitters. A tap coefficient is varied at a prescribed interval in a frame period using a plurality of PN seeds used in the plurality of CDMA transmitters and synchronization of signals transmitted from the plurality of CDMA transmitters is acquired. The construction of the apparatus is thus simplified and multi-user signal synchronization is acquired within one frame time, which is the shortest time.

Abstract: A communicating apparatus performs an asynchronous communication with a base station. The communicating apparatus is provided with: a receiving device for receiving a down link signal, which is transmitted from the base station and in which a division signal is inserted for each of constant time intervals; a detecting device for detecting division signals out of the received down link signal, in phase to the constant time intervals; an adding device for adding the detected division signals over a predetermined time duration, which is longer than the constant time interval, with matching phases for each of the constant time intervals, so as to generate accumulated additional values; and a memory device for storing the accumulated additional values generated by the adding device, to thereby perform synchronization capturing with the base station on the basis of the accumulated additional values added over the predetermined time duration and stored in the memory device.

Abstract: A first initialization pattern signal is a signal in which a maximum signal level and a minimum signal level appear alternately, and a second initialization pattern signal is a signal in which all signal levels appear in a predetermined arrangement. In a ring-shaped network including plural stages of data transmission apparatuses (100), a transmission unit (110) of each data transmission apparatus outputs the first initialization pattern signal successively to a next-stage data transmission apparatus at turn-on of power or immediately after reset, and a reception unit (120) establishes clock synchronization on the basis of the first initialization pattern signal received.

Abstract: A method and apparatus for mitigating multipath interference in a digital signal correlator forms values representative of magnitude or power of a correlation response between a digital signal and a pseudorandom reference code. The earliest peak in the correlation response is then selected as the correct peak to compute a time delay.

Abstract: Systems and methods are disclosed for time synchronization of operations in a control system. Synchronization networks and devices are provided for transferring synchronization information between controllers in a distributed or localized control system, which is employed in order to allow operation of such controllers to be synchronized with respect to time. Also disclosed are synchronization protocols and hardware apparatus employed in synchronizing control operations in a control system.

Abstract: Collisions between messages simultaneously transmitted by multiple spread-spectrum transmitters are reduced by distributing the transmissions over the available resources of the receiver. Each mobile station in a CDMA system uses one or more randomization methods to distribute its transmissions. In the first randomization, the mobile station time-delays its transmissions by a number of chips of the PN code with which it spreads the transmitted signal. In a second randomization, the mobile station randomly selects the PN code. In a third randomization, the mobile station inserts a random delay between successive message transmissions or probes if it does not receive an acknowledgement after a predetermined timeout period. A predetermined number of such transmissions is called a probe sequence. In a fourth randomization, the mobile station inserts a relatively long random delay between successive probe sequences if it does not receive an acknowledgement of any probe in the sequence.

Abstract: An improvement for a method and system for tracking a spreading code, used in a code division multiple access (CDMA) system. An input signal has spread-spectrum modulation. The spreading code embedded in the spread-spectrum modulation has a plurality of chips. The input signal is sampled, and half-chip offset samples are formed from the sampled input signal. An even set of the half-chip offset samples are grouped into an early set of samples, and an odd set of the half-chip offset samples are grouped into a late set of samples. Each early set of samples is multiplied by the spreading code c(n+1), c(n+2), . . . , c(n+L), to generate a first plurality of products. L is approximately equal to the number of chips of delay between the earliest and latest multipath signals. A first plurality of sums and magnitudes are computed from the first plurality of products. The first plurality of magnitudes are summed to generate an early signal-energy value.

Abstract: Described is a system and method related to the synchronization of a communication stream between two devices. A broadcast signal is a segmented information signal that includes a distributed synchronization pattern and a distributed frame index. Each segment of the segmented information signal further includes a header portion and a payload portion. The header portion of the segmented information signal includes a portion of the distributed synchronization pattern and a portion of the distributed frame index. The method includes generating the distributed synchronization pattern and the distributed frame index, distributing the synchronization pattern and frame index throughout the signal, and transmitting the signal.

Abstract: A method, apparatus and system detects a loss of synchronization between a transmitter and a receiver in a multiple-carrier communication system such as an OFDM system. A phase-frequency synchronization detector determines when the receiver has lost synchronization with the transmitter based on a phase-frequency relationship of plurality of pilot signals transmitted at different frequencies from the transmitter and received at the receiver. A loss of synchronization is detected when a slope of a line defined by the phase-frequency relationship exceeds a timing threshold more at a rate in excess of an occurrence threshold within a time period.

Abstract: A remote power meter monitoring system using spread spectrum transmitters, fast frequency shift keying, spread spectrum receivers and a computer. The spread spectrum transmitter uses a chip code generator, preamble register, address register data register and oscillator coupled to a microprocessor to transmit information in a direct sequence spread spectrum signal. The spread spectrum receiver acquires synchronization of the spread spectrum signal using a microprocessor to despread and detect the transmitted information, which relates to data from a power meter.