Abstract: The present invention discloses methods, apparatuses, and systems for eliminating auto- and cross-correlation in weak signal CDMA systems, such as GPS systems. The invention uses parallel data paths that allow standard correlation of signals in parallel with verification of the lock signal to determine whether the system has locked onto the proper signal within the scanned signal window. The invention can be made with multiple CPUs, a single CPU with dual input modes, on multiple IC chips, or as a single IC chip solution for small, low cost reception, downconversion, correlation, and verification systems.

Abstract: A mobile communication system receives a reception signal of a reception signal, and performs a control operation such that a weight for generating a reception beam is calculated using a first technique if a difference between an error sum value at a current time and an error sum value at a previous time is greater than an absolute value of a first threshold or the error sum value at the current time is greater than or equal to a second threshold, and performs a control operation such that the weight is calculated using a second technique if the different between the error sum value at the current time and the error sum value at the previous time is less than or equal to the absolute value of the first threshold and the error sum value at the current time is less than the second threshold.

Abstract: A method and apparatus of joint processing a plurality of digital signal streams is disclosed. The method includes transforming a plurality of the digital signal streams from an original domain to a lower complexity processing domain. The transformed plurality of digital signal streams are joint processed, wherein the joint processing includes multiplying samples of the plurality of transformed digital signal streams by a processing matrix. The joint processed signal streams are inverse transformed back to the original domain. Diagonal elements of the processing matrix are adaptively selected to cancel transmission echo signals of the plurality digital signal streams introduced during transmission of the plurality digital signal streams depending upon signal coupling of the plurality of digital signal streams.

Abstract: A GPS system is configured to manage interference from disturbing signals. The system includes an antenna, an RF front end unit, a filtering unit, amplifying circuits, a carrier recovery unit, a correlation unit, and a calculating unit that performs range calculations. A multiplying unit, which is positioned between the carrier recovery unit and the correlation unit, is adapted to multiply the signal from the carrier recovery unit to the correlation unit with either zeros, “0”, or ones, “1”, and a control logic unit is configured to control the multiplying unit into using zeros, “0”, if interference is detected and into using ones, “1”, if no interference is detected.

Abstract: A system, method, apparatus, means, and computer program code for improving accuracy of radio timing measurements. According to some embodiments, a wireless terminal or other wireless device can make adjustments to a measurement made from a radio transmission source by adjusting timing measurements using a weighted average and/or synchronizing its timing to the timing of this or some other radio transmission source. The adjusted measurements can be obtained for times other than when the original measurements are made. Measurements for multiple radio transmission sources can then be adjusted to a common time wherein adjustment errors due to unknown timing drift in the radio sources and wireless terminal and Doppler errors due to unknown relative velocities can be reduced or eliminated.

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 communications system of the present invention includes a transmitter that is operative for combining an orthogonal Walsh modulation with a minimum shift keying or Gaussian minimum shift keying waveform to form a hybrid communications signal that carries communications data over a constant amplitude waveform that is spread in time and frequency. This communications signal can be transmitted to a RAKE receiver that has a plurality of correlators with output weights formed for processing this hybrid communications signal.

Abstract: An autocorrelation filter for use with a spread spectrum receiver. The autocorrelation filter can be used as a prefilter stage to reduce phase distortion present in a spread spectrum signal. The autocorrelation filter can be used to process the output from a lattice filter. The lattice filter is configured to remove magnitude distortion from the spread spectrum signal. The autocorrelation filter performs a series of correlations on the output of the lattice filter. The results of these correlations are integrated over a period of time to generate a running impulse response for characterizing and removing the phase distortion in the spread spectrum signal.

Abstract: A method and device for processing a received signal by detecting within the received signal a plurality of possible symbols transmitted by or for a plurality K of users, each of the plurality of possible symbols belonging to a modulation constellation and being the subject of a spectral spreading by a spreading sequence. The step of detecting includes substeps of: a) filtering the received signal by supplying a complex vector characteristic of the received signal and decomposing the complex vector into real and imaginary vectors; b) separately searching for a closest neighbor of the real vector and a closest neighbor of the imaginary vector within a respective real and imaginary lattice of points corresponding to the modulation constellation; and c) estimating the transmitted symbols from components of the closest neighbor of the real vector and the closest neighbor of the imaginary vector to produce a vector of estimated symbols.

Abstract: Methods and systems for demodulating a multiuser signal using channel decoders for a multiple-access communication system are disclosed. According to one method, a signal containing information for a plurality of users in a multiple-access communication system employing spreading sequences is received. The received signal is despread using a signature sequence for each user to produce individual user signals having multiple-access interference (MAI). Channel estimates associated with each of the individual user received signals are determined. Each of the individual user signals are decoded using a channel decoder with a log-likelihood ratio (LLR) that accounts for the time-varying variance of the MAI in the individual user signals based on a model of the MAI including the channel estimates of the received signals of other users.

Abstract: The invention relates to a receiver in a spread spectrum system, comprising reception means for receiving a spread spectrum signal. The receiver comprises interference cancellation means configured to cancel multiuser interference and external interference from the received spread spectrum signal in one or more interference cancellation stages. The invention further relates to an interference cancellation method in a spread spectrum system.

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: An apparatus and method for canceling narrow-band interference in a wideband mobile communication system. The apparatus includes a down converter for down converting a received signal into a baseband signal, an analog-to-digital converter for converting the baseband signal into a digital signal, a decimation filter for decimating the digital signal according to a decimation ratio, an interference canceller for detecting narrow-band interference signals contained in an output of the decimation filter, and canceling the narrow-band interference signals, and a demodulator for demodulating an output of the interference canceller.

Abstract: A system and method is provided for determining a channel estimate utilizing partial channel estimates to provide an aggregated channel estimate. A partial channel estimate is determined upon receipt of a data burst, such that a different subset of the channel estimate is updated every data burst. As a result, Fast Fourier Transform computations can be reduced by determining a portion of the channel estimate each data burst as opposed to determining a full channel estimate every data burst.

Abstract: A narrowband interference cancellation system, method and digital signal processor is disclosed that removes narrowband interference in wide band communication systems. The system includes a narrowband processing component, wideband processing component, soft metric generator and at least one filter. The system is configured to receive a signal, identify one or more narrowband interferers in the received signal and filter out identified narrowband interferers. The narrowband processing component includes a filter bank configured to separate the received signal into a predetermined number of channel bands and identify a band with interference. The wide band processing component provides an average level for an unfiltered version of the received signal. The soft decision metric generator produces metrics based on predetermined thresholds.

Abstract: The present invention relates to a new parallel interference cancellation (PIC) configuration where the PIC is implemented after the rake reception and multipath combining. In the invention disclosed, the regenerated interference contributions (functions of signature sequence cross-correlations) for multiuser detection (MUD) in a multipath radio channel are explicitly filtered through the estimated multipath channels, and stored. These stored quantities already contain the effect of the channel, and only need updating according to the rate of change of channel dynamics, and not the symbol period. During each symbol period, interference is computed from each interfering user to each desired user using current estimates of symbol decisions and the aforementioned interference contributions. The precomputation of the interference contributions, which are valid for a sequence of symbols, allows for extremely low complexity baseband processing in the receiver.

Abstract: A method for double weighting parallel interference cancellation in CDMA mobile communication system, integrates ideas of both partial weighting method and weighting method based on Bayes rule. When making a decision on each symbol of the user, calculating reliability coefficient of a decision result on the symbol of the user according to the weighting algorithm based on Bayes rule; weighting regenerated signal of the symbol of the user with the reliability coefficient. During process of MAI estimating and removing, obtaining the MAI on the expected user from weighted regenerated signal of other users in chip level; and then setting a weight value, weighting the MAI with the weight value. Finally, removing weighted MAI from received signal, which means partially removing MAI produced by other users on the expected user.

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 hybrid receiver, and an associated method, for receiving a radio signal carrying transmitted data that is subject to distortion in the transmission channel. The receiver includes a plurality of stages that perform parallel interference cancellation (PIC) to establish successively more accurate estimates of the transmitted data, including a receiver first stage being either a RAKE receiver or a linear minimum mean-square error (LMMSE) receiver, a second stage including an LMMSE, and preferably a third stage also including an LMMSE. Each stage processes the estimates of the transmitted signal provided by the stage preceding it to mitigate or eliminate as much transmission-channel interference as possible and prove a refined estimate for processing by subsequent stages. Improved channel estimation may be achieved by processing the pilot signal in similar fashion as well.

Abstract: A signal generation/noise extraction unit that includes an analog-to-digital converter, a switch, a filter, a subtracter, an oscillator, a multiplier, and a switch generates a down-sampled signal at a frequency at which aliasing occurs, from an input signal, and extracts an aliasing noise component included in the down-sampled signal. A dispreading unit includes a (1/n)× over-sampling matched filter, a 1× over-sampling matched filter conducts dispreading processings to the down-sampled signal and the aliasing noise component. A noise canceling unit includes filters, a multiplier, an adder, and a switch combines two dispreading results, and cancels the aliasing noise component.

Abstract: A CDMA demodulation circuit to be adapted to fluctuation of arrival path timing and to obtain good reception characteristics, can be provided. A despreading timing correction control portion controls number of despreading timing correction candidates depending upon result of comparison in a correction value difference calculating portion. An effective path timing judgment portion makes judgment of an effective path timing on the basis of correlation peak information detected by the correlation value difference calculating portion. Respective despreading portions perform despreading at a plurality of timings including a path timing set from the effective path timing judgment portion and despreading timing correction candidates of M points before and after the set path timing.

Abstract: Methods of recovering data in a received signal sent in a communications media are disclosed. Composite channel impulse responses are first estimated. Channel-tap locations are then assigned to suppress the interference noises by sequential search schemes or heuristic search schemes based on estimated composite channel impulse responses. A sequential search scheme optimizes a predetermined design criterion in a sequential manner. Also described are recursive evaluations of the design criterion and the inverses of the noise covariance matrices based on the composite channel impulse response during a sequential search. A heuristic search scheme selects channel-tap locations based on a set of pre-selected channel-tap locations. The set of pre-selected channel-tap locations is determined according to the estimated composite channel impulse response. A method of estimating energy levels of known interference sources is also described.

Abstract: Aspects of a method and system for a variable spreading factor Walsh Hadamard Transform engine are presented. Aspects of the system may include a variable spreading factor Fast Walsh Hadamard Transform engine that enables spread spectrum encoding of data from each of a plurality of data sources. A plurality of spreading factors may be utilized wherein at least 2 of the plurality of spreading factors differ. The variable spreading factor Fast Walsh Hadamard Transform engine may enable combination of a plurality of spread spectrum encoded data to form a data vector.

Abstract: Iterative detection for a MIMO (multiple-input, multiple-output) wireless communications system uses multiple stages for interference cancellation refinements. Detection is determined by maximizing signal to noise plus interference ratios. Equalization matrix updating uses a matrix-inversion-free recursion. For P transmitter antennas and Q receiver antennas, the soft symbol vector estimates are z=Fr?Gshard with F a P×Q IMMSE detector, r the received Q vector, and G a P×P interference canceller with shard hard decisions of prior symbols and iterations.

Abstract: This disclosure is generally directed to communication systems, devices used in communication systems and associated methods which may implement parallel hypothesis search techniques. The disclosed parallel hypothesis search techniques may permit a hypothesis to be dismissed early (i.e., before hypotheses in other searchers have completed their evaluation). Early hypothesis dismissal permits a new hypothesis to be loaded into the searcher while other searchers advantageously continue to evaluate their hypotheses.

Abstract: There is provided a method and apparatus for selecting an appropriate base station and an optimal data rate to provide a voice service and a data service based on a voice service load in a CDMA system. A base station transmits two pilot signals orthogonally spread with different orthogonal codes in association with its voice service load, and a mobile station estimates the voice service load based on a pilot power ratio.

Abstract: A method for facilitating broadband multi-carrier wireless transmission, whereby a plurality of transmit antennas are divided into two or more transmit antenna groups of transmit antennas so that the correlation between antennas in each group is minimized, and each group of antennas transmits on a predetermined frequency with a different time periodicity, and each transmit antenna in each group transmits training sequences which are reciprocally time-orthogonal. Each of a plurality of receive antennas receives signals from each transmit antenna group. The signals from each group are separated via a band-pass filter, and a maximum estimation range of a frequency offset estimation algorithm is determined by the group having the shortest time period, and the accuracy of the frequency offset estimation algorithm is determined by the group having the longest time period. The received signal is corrected with the frequency offset.

Abstract: The invention relates to methods of processing signals subjected to interference. It consists, when this signal is formed of a first wideband channel and of a second narrowband channel modulating one and the same carrier in which these signals are cut off for the duration of the interference, in using a single phase loop and a single code loop to process these two channels simultaneously. It makes it easier to process signals in satellite based navigation systems of the GPS type when they are scrambled by the DME-type distance measuring system signals, as well as more generally making it possible to increase the robustness of the processing by joint processing of the bands broadcast to the users.

Abstract: The N peaks are selected from a delay profile in order starting from the highest peak involved in the delay profile, the path level and path timing are determined for each of the selected peaks, and the identical paths individually responsible for different delay profiles are detected by comparing the path timings calculated for the preceding time and the path timings calculated for the present time. Based of the path levels calculated for the preceding time and the path levels calculated for the present time, averaged path levels are computed on a path-by-path basis for the present time, a predetermined threshold is applied to the computed average path levels, and the paths to be allocated to the fingers are selected. Of the path timings that have been obtained for respective selected paths, the latest path timings are allocated to the fingers as synchronization timings.

Abstract: In a compressed mode, a spread spectrum communication device interleaves bit units across multiple frames using an interleaver, reduces the spreading factor using a framing/spreading unit, outputs the compressed mode frames at a predetermined compressed mode frame timing, and increases the average transmission power in the compressed mode at a radio frequency transmitter. Furthermore, a handover between different frequencies is carried out by establishing synchronization to another frequency carrier, based on a first search code and a second search code which have been detected, and moreover, a handover between different communication systems is carried out by establishing synchronization to a GSM, based on an FCCH and a SCH which have been detected.

Abstract: A method for transmission of data signals between a master station and multiple slave stations, as well as a master station and a slave station are provided, permitting distortion of predistorted data signals. Data signals are transmitted between the master station and multiple slave stations via wireless channels, data signals for different slave stations being spread using different codes in the master station, a predistortion of the data signals to be transmitted being performed, and in predistortion the transmission properties of all wireless channels and the different codes are considered. The data signals to be transmitted are predistorted by filtering in the master station.

Abstract: An apparatus, such as a subscriber unit or a base station within a spread spectrum communication system, provides advanced control over the time-tracking of demodulation elements when unresolvable multipath situations arise. The apparatus provides merge protection that prevents clustered demodulation elements from contracting beyond a minimum time span. In addition, the apparatus provides a master/slave feature for synchronizing the time-tracking of the demodulation elements when clustered around a multipath signal.

Abstract: A narrowband interference excision method and apparatus. According to one embodiment, a method for narrowband interference excision is disclosed. The method comprising transforming time domain data into a frequency domain vector having a plurality of frequency bins. The method further comprises estimating a plurality of power values corresponding to frequency bins of the frequency domain vector to obtain a current power vector. Then, calculating an average power vector from the current power vector and at least one selected previous power vector. Further, excising selected frequency bins of the frequency domain vector to produce an excised frequency domain vector. Moreover, determining whether to include the average power vector in future average power vector determinations. In another embodiment, a narrowband interference excision apparatus is disclosed.

Abstract: A method and apparatus to estimate the channel fade (both the amplitude gain/loss and the phase rotation) to assist the receiver to detect and recover the transmitted signal employs a continuous pilot signal such as the pilot code channel or pilot symbols. The channel estimator uses the same scrambling pattern of pilot channel and coherently integrates the continuous pilot signal to yield a channel estimate. The present invention employs adaptive integration duration to yield a channel estimate. The integration duration of the pilot signal for channel estimation is adaptive and proportional to the Doppler period. The Doppler period is proportional to the inverse of Doppler frequency and is an indicator of how fast the channel changes.

Abstract: A Doppler frequency is detected with a high degree of accuracy, deterioration of a transmission diversity effect is prevented, and a good reception property is secured. A reception demodulating unit of a portable communication apparatus according to the present invention has a path search and path selection unit for searching and selecting an optimum path, finger processing units for obtaining a phase variation component as a channel estimated value for each path and coherent-detecting by using its channel estimated value and a phase difference measuring unit for measuring a phase difference, a path timing difference measuring unit for measuring a periodical path timing difference, a frequency error detecting unit for detecting a frequency error of a signal by using a path timing difference and a phase difference, and a Doppler frequency detecting unit for detecting a Doppler frequency on the basis of a frequency error.

Abstract: A communication system is provided herein for transmitting frames across a channel. The frames may be transmitted in single-input, single-output (SISO) and/or multi-input, multi-output (MIMO) communication systems. One such frame includes at least one training symbol, each having a cyclic prefix and a training block. The time length NI of the training block is equal to an integer fraction I of the time length of a data block, i.e., NI=N/I. Furthermore, the time length G of the cyclic prefix is an integer fraction of the time length NI. For example, G may be equal to NI/4 or 25% of NI. The training symbols provide coarse and fine time synchronization, coarse and fine frequency synchronization, channel estimation, and noise variance estimation.

Abstract: The invention relates to a method for multiple access interference suppression and to a receiver applying the method. A preliminarily detected signal is spreading coded and channel distorted in a MAI estimator (350) for generating an estimate signal (274) corresponding to a received and reception-filtered signal. Pulses (360) corresponding to a signal component of each path of each user are generated from the signal in a pulse generator block (300), and the pulses are combined according to path delays into a pulse sequence (362) in a combiner (310). In a filter (312), the pulse sequence (362) is subjected to waveform filtering, which is the convolution of reception filtering and pulse shaping filtering. Finally, in a summer (220), the estimate signal (274) is subtracted from the received and reception-filtered signal (270) to cancel multiple access interference.

Abstract: An interference canceller is herein disclosed wherein a baseband signal is input to a detector's fingers, and the fingers detect multi-path signals and estimate the baseband signal's channel. An MRC uses the finger's despread signal and the channel estimate to output a soft bit decision value, while a signal regenerator uses a hard bit decision value and the finger's channel estimate to regenerate the baseband signal. An SIR measurer uses a soft bit decision value and a despreader's channel estimate to measure an SIR. A signal selector compares each detector's SIR measurement value with a target SIR, and when the SIR measurement value is greater than the target SIR, it selects the detector's regeneration signal to group received signals. A subtractor subtracts the regeneration signal from the baseband signal.

Abstract: A device communicates with a host and includes a transmitter, a receiver and a clock generator that generates a signal having a local clock frequency. A clock recovery circuit communicates with the receiver and recovers a host clock frequency from data received from the host by the receiver. A frequency offset circuit communicates with the clock recovery circuit and the clock generator and generates a frequency offset based on the clock frequency and the recovered host clock frequency. A frequency compensator compensates a frequency of the transmitter using the frequency offset. The host and the device may communicate using a serial ATA standard. Frequency compensation can be performed during spread spectrum operation.

Abstract: The present invention provides a method and system for operating a wireless communication system in which received signals from a plurality of antennas are weighted and combined with a beam forming operation to form an output signal. The beam forming operation determines weights adjusted to increase a desired signal power in the output signal while reducing the power in the output signal of out-of-band components. In an embodiment of the present invention, beam forming operations are performed with maximal ratio combining (MRC). Alternatively, a constant modulus algorithm (CMA) can be used for beam forming operations. In an alternate embodiment, improved interference suppression is performed with a novel algorithm referred to as an interference nulling algorithm (INA). The INA receives an error signal which is 180° out of phase with a combination of the channels for individual antennas, referred to as the SUM channel.

Abstract: Systems and methods are provided for directionally filtering signals by projecting a received signal onto a subspace substantially orthogonal to selected interfering signals. The received signal typically comprises at least one signal of interest, at least one selected interfering signal, and noise. The received signal may further comprise other signals, including non-selected interfering signals. The projection of the received signal results in substantially no contribution from the selected interference signals on the signal of interest. For example, substantially no residual energy of the selected interference signals remains as an influence on the signal of interest. In one embodiment, a system generates a converted matrix having a substantially orthogonal set of vectors. Each vector may represent one or more selected interfering signals. The vectors may comprise code characteristics of the selected interfering signals. A directional filter uses the matrix to perform the projection.

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: A system for reassigning a plurality of tracking units of a wireless receiver, for receiving a plurality of multipath signals in a predetermined time period to reconstruct correspondingly an original signal. The system includes a searcher, a tracker and an assigning management unit. In particular, a predetermined estimating process includes the following steps to generate the assigning value of a combination of matching pairs: subtracting the searching time position and the predetermined tracking time position of every matching pairing the combination and taking absolute values to obtain a plurality of corresponding subtraction values; inputting the plurality of subtraction values to a predetermined estimating function to obtain a plurality of corresponding estimation values; and summing up the plurality of estimation values and obtaining the assigning value of the combination of matching pairs.

Abstract: A multiband ultra wideband (UWB) communication is presented to implement multichannel shaped-pulses in parallel for indoor and outdoor UWB operations. The multiband UWB communication has a flexibility to transmit and receive a scalability data rate on the multichannel with lower power consumption.

Abstract: Mobile station equipment, base station equipment, and an exchange equipped with all or some units for monitoring the speed of a mobile station, making a judgment whether or not the speed exceeds a given threshold value, and restricting both or at least one of channel control and call processing regarding a call occurring at the corresponding mobile station. These mobile station equipment, base station equipment, and exchange operate alone or associate with each other through radio transmission paths or other links. Further a mobile communication system may include these mobile station equipment, base station equipment, and exchange. In the above equipment exchange, accidents normally caused by some operation of an operator on the mobile station equipment in response to a call occurring in the mobile station equipment moving at a high speed are prevented efficiently and reliably.

Abstract: Received signals of the respective sub-carriers are multiplied by a weighting controlled for each sub-carrier, using a weighting control part 2-8 and multipliers 2-9, so that the mean square error between the signals following despreading and the signals that are actually transmitted is minimized. Afterward, MMSE combining is performed.

Abstract: A RAKE receiver device includes a plurality of fingers for demodulating multipath receive data, and a data synthesis circuit for synthesizing the receive data from each of the paths and demodulated by the plural fingers. Each time the receive data is demodulated by one of the plural fingers, the data synthesis circuit adds cumulatively the demodulated receive data for each identical receive data from each of the paths, and synthesizes the data.

Abstract: A transceiver is disclosed. The transceiver includes a plurality of digital signal streams, wherein at least one digital signal stream is coupled to another of the digital signal streams. A transform block transforms a plurality of the digital signal streams from an original domain into a lower complexity processing domain. A processor joint processes the transformed digital signal streams, each joint processed digital signal stream being influenced by other digital signal streams. An inverse transform block inverse transforms the joint processed signal streams back to the original domain. A method of joint processing a plurality of digital signal streams is also disclosed. A first act of the method includes transforming a plurality of the digital signal streams from an original domain into a lower complexity processing domain.

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: In an automobile on-board and/or portable telephone system capable of increasing the capacity of subscribers easily on the basis of changing of the information transmission bit rate, spread codes obtained by multiplying orthogonal spread codes (m in number) by a pseudo-random noise series are assigned to individual channels in the same cell in such a manner that the orthogonal spread codes are multiplied by some types of pseudo-random noise series having different phases, thereby making it possible to maintain the number of channels in the same cell at a value which is a multiple of the number of the orthogonal spread codes.