Abstract: A digitally sampled spread spectrum signal is received, despread, and accumulated at a center frequency lower than the sampling rate and higher than zero.

Abstract: The present invention provides a system and method for radio communications wherein the transmitted signals include an intermediate frequency in addition to a carrier frequency to aid in demodulation of data modulated on the signals and regulate the local oscillator frequency at the receiver. The invention greatly reduces the number of components required to implement a radio, and in particular, a direct sequence spread spectrum radio, reduces the frequency stability requirement at the transmitting and receiving ends of the communication, automatically tracks changes in the transmission signal after transmission, and permits the use of a single frequency reference to provide all required frequencies to operate both the receiver and the transmitter in each radio.

Abstract: An orthogonal transform processor which can be implemented in simple hardware. A data reception unit accepts a pair of source data values at intervals of T. For each given pair of source data values, an adder/subtractor performs addition and subtraction at intervals of T/n, where n is an integer representing the order of the orthogonal transform algorithm being implemented. The resultant data values are stored in some predetermined storage locations defined in a storage unit. A feedback unit reads out such stored data values from the storage unit and feeds them back to the adder/subtractor. When the intended operation stages are finished, a data output unit reads out the data from the storage unit and sends them out as the final result values.

Abstract: A deskew buffer 410 arrangement in a CDMA receiver allows for accurate combining of symbols from a plurality of demodulator fingers, 402 and 404, without any symbol losses when the data rate is changed. A single deskew buffer 410 is coupled to a plurality of demodulator fingers, each of which demodulate an assigned multipath. The symbols are written into the deskew buffer 410 according to a PN count value modified by a predetermined bit pattern. The demodulator finger is able to demodulate a plurality of data rates corresponding to a plurality of Walsh lengths. Each data rate is assigned a corresponding deskew index. The PN count value represents an address within the deskew buffer 410. The lower bits of the PN count, where the number of bits corresponds to the deskew index, are truncated and replaced with the predetermined bit pattern. In one embodiment the predetermined bit pattern is all ones.

Abstract: A method and apparatus related to a communication system in which a plurality of remote units encode data bursts using a predetermined codeword set and transmit the encoded data bursts to a hub station over a multiple-access channel. When the hub station receives a data burst from one of the remote units, the hub station demodulates the received data burst and correlates the received data burst with each codeword within the predetermined codeword set to determine which codeword has the maximum correlation. The hub station uses the correlation to derive a timing synchronization signal and/or a carrier frequency adjustment signal to be sent back to the remote unit. The signals provide information to the remote unit to synchronize its timing or adjust its carrier frequency for transmitting subsequent data bursts. The hub station may also use the correlation to estimate a signal-to-noise ratio.

Abstract: A cell searching apparatus and method in a mobile communication system. In the cell searching method, a base station group specific code is determined from a synchronization channel signal in synchronization with slot time. Then, the predetermined base station group specific symbol cyclically reads a base station group specific code table. A code with a minimum distance estimation value with respect to a base station group specific code read from the base station group specific code table is chosen as a final base station group specific code.

Abstract: Dynamic Time Metered Delivery (DTMD) is a unique physical layer communication Method. DTMD uses enhanced time-based techniques to enable and control the flow of more data/Hertz through a variety of transmission media including existing and new copper phone lines, coaxial cable, fiber optic, powerline and wireless RF, Optical and Acoustic, to and from a comprehensive, multi-function customer data gateway. The system measures the transmission parameters as viewed from the “end of the line” and then sends these numerics back to the source which alters the shape of the basic signal structure such that when received at the far end, it will have maximum recognition attributes against interferers and noise. The present system and method add the adaptivity to the line conditions and set a maximum allowable data rate within the subscribed levels of performance.

Abstract: A transmission method for implementing variable rate transmission. Part of the baseband processing of a transmitter based on a CDMA transmission scheme is described. A transmitted information sequence in the form of a digital signal is phase modulated by a phase modulator 105. An orthogonal code generator 101 selects, in response to rate information of the transmitted signal, the orthogonal code to be generated. The bit rate of the orthogonal code the orthogonal code generator 101 generates is double the maximum transmission rate. The modulated transmitted signal is multiplied by the orthogonal code corresponding to the rate information with a multiplier 103. The transmitted signal, which is multiplied by the orthogonal code corresponding to the rate information, is further multiplied by a spreading code sequence with a multiplier 104 to be spread into a CDMA signal, and is transmitted under power transmission control based on the rate information.

Abstract: A terrestrial C/A code GPS receiver system digitally samples, filters and stores a segment of 11 half chips of the received composite as a binary number and multiplexes this number for parallel correlation with each of a series of multibit code replicas for the satellites to be tracked. Each of the time delay specific correlation products are accumulated in a cell of a memory matrix so that at least twenty two delays for each satellite may be evaluated each code period providing fast reacquisition, even within a city intersection, as well as correction of multipath tracking and multipath interference. All cells of the memory matrix may be used for an acquisition of a single satellite in about 4 ms. Two satellite tracking, in addition to altitude hold, uses cross track hold alternating with clock hold to update the cross track estimate. Single satellite tracking uses cross track and clock hold together. Navigation data is updated with detected changes in motion including turns.

Abstract: A correlation circuit arrangement for de-spreading spread spectrum signals. In various embodiments, the correlation circuit arrangement includes an adder-subtractor and a shift register arrangement. The adder-subtractor adds an input sample value to or subtracts the sample value from an accumulated correlation value, responsive to an input PN code. The adder-subtractor is time-multiplexed between one or more PN code generators and correlation values are accumulated in the shift register arrangement. In another embodiment, transmission path delay can be analyzed by using the shift register arrangement to store correlation values that result from delaying the PN code across multiple chip periods.

Abstract: An improvement to a spread-spectrum receiver having a matched filter. A symbol sampler samples at the symbol time TS, a symbol sample from the matched filter. A noise sampler samples at a plurality of chip times kTC, but not at the symbol time TS, a plurality of noise samples from the matched filter. An estimator or low-pass filter estimates the plurality of noise samples from the symbol sampler, to generate a noise estimate. A combiner subtracts the noise estimate from the symbol sample, thereby generating a comparison signal. A magnitude device determines a magnitude of the comparison signal. A comparator compares the magnitude of the comparison signal to the threshold voltage, thereby generating the erasure signal. An erasure decoder erasure decodes the input data using the erasure signals from the erasure detector.

Abstract: An improvement to a spread-spectrum code-division-multiple-access system, using a channel sounding signal from a base station (BS) to provide initial transmitter power levels for remote stations (RS). The base station transmits BS-spread-spectrum signals at a first frequency and receives RS-spread-spectrum signals, which are transmitted by the remote stations at the second frequency. The base station transmits a BS-channel-sounding signal at the same carrier frequency being used by the remote stations. The bandwidth of the BS-channel-sounding signal is much less than the bandwidth of the BS-channel-spread-spectrum signal. Each remote station tracks the BS-channel-sounding signal, for adjusting the initial RS-power level.

Abstract: A method and apparatus for searching for neighboring base stations by waking from a power-saving sleep mode to receive an incoming signal. The incoming signal is received and at least a portion of the incoming signal is stored. The stored information signal is then processed with each of several different codes to determine a power level corresponding to each of the different codes.

Abstract: A correlation energy detector detects a magnitude of a correlation between a first signal series (Ii, Qi) described by I-Q orthogonal components and a predetermined second signal series (HJ). The correlation energy detector includes a correlation computing section for computing correlation values (Iij, Qij) between the first signal series (Ii, Qi) and the predetermined second signal series (HJ), and a root computing section for computing {{square root over ( )}(Iij2+Qij2)} as a root value of a sum of squares of the correlation values (Iij, Qij) obtained from the correlation computing section.

Abstract: A demodulation method in a mobile station having a plurality of channels, for receiving a signal from a base station. In one aspect, the base station has a plurality of channels, a BPSK spreader for orthogonally spreading symbol data of each channel with an assigned orthogonal code, and a QPSK spreader for PN-spreading the orthogonally spread signal with a PN code. In the demodulation method, a first QPSK despreader in the mobile station receives PN-spread signal and PN-despreads the PN-spread signal with the PN code, and a second QPSK despreader orthogonally despreads the PN-despread signal with a complex orthogonal code having the real and imaginary parts of the assigned orthogonal code. In another aspect, the base station has a plurality of channels, a QPSK spreader for spreading symbol data of each channel by the real and imaginary parts of its assigned orthogonal code, and a QPSK spreader for PN-spreading the orthogonally spread signal with a PN code.

Abstract: An optimum combiner that reduces the amount of interference imposed upon a first base station by transmissions of other base stations within the same communication system. Two antennas are used to receive transmissions within a receiving station. A rake receiver is coupled to each antenna. By optimally combining the signals that are received by each independent finger of the rake receiver, interference that is correlated between a finger associated with the first antenna and a finger associated with the second antenna can be minimized with respect to the desired signal. Optimum combining requires determination of optimum combining coefficients. A max-ratio combining algorithm may be substituted for the optimal combining algorithm depending upon interference characteristics.

Abstract: An analog input signal that is sampled at a predetermined rate is multiplied by a corresponding binary code sequence, i.e. “+1” or “−1” by the multiplier. The output of this multiplier is applied in conjunction with a signal supplied by the negative feed back circuit to the analog integrator. The quantization circuit quantizes the output signal of the analog integrator into N levels and outputs a digital word. This digital word is delayed by a unit time interval by a digital delay circuit and then processed by the above mentioned negative feed back circuit. As a result of this signal magnitude reducing process, the required integrating capacitance can be minimized without risks of saturation effects. Additionally, the output is already in digital form as required by the subsequent system blocks.

Abstract: In systems which transmit both GSM modulated and EDGE modulated signals, time of arrival estimations can be improved without requiring the detection of the type of modulation used on the received signal. In accordance with the present invention, a received signal is initially demodulated by a receiver in accordance with a first demodulation scheme. The demodulated signal is split into two copies. Taking into account the initial demodulation, one of the copies is demodulated in accordance with another demodulation scheme, thereby resulting in a first signal demodulated in accordance with the first demodulation scheme and a second signal demodulated in accordance with a second demodulation scheme. A training sequence is used to correlate the two signals which are then summed in a incoherent integration process. The result of the incoherent integration is used to estimate the time of arrival of the received signal.

Abstract: A mobile communication device has a delay locked loop circuit for carrying out a tracking synchronization of a reception signal. The reception signal may be a spread spectrum signal. The delay locked loop circuit comprises a generating section for generating an early signal and first and second late signals which are different in phase from one another. A multiplying section is for multiplying the reception signal by each of the early signal and the first and the second late signals to produce first through third multiplied signals. A producing section produces an tracking error signal in accordance with the first through the third multiplied signals. A supplying section supplies a clock signal to the generating section on the basis of the tracking error signal to make the generating section generate the early signal and the first and the second late signals.

Abstract: A radio communication apparatus subjects each signal which is received via a multi-path and demodulated, to a Hadamard transform at each of fingers, by use of an M-ary quadrature coding scheme, obtains correlation values of codes, combines correlation values output from fingers which obtain valid correlation values, and demodulates a received signal based on a maximum correlation value of combined correlation values. The radio communication apparatus includes an operation unit which obtains a difference between a maximum value and a second largest value of the correlation values of a corresponding one of the fingers, and a lock controller which enables and locks the correlation values output from the corresponding one of the fingers when the difference obtained by the operation unit is greater than or equal to a predetermined value.

Abstract: A method for estimating and compensating for a fading communications channel includes the steps of generating matched filter data from a received data burst, interpolating between reference symbols to generate a fading channel estimate from the matched filter data, applying a phase correction to the matched filter data from the fading channel estimate to recover free data from the matched filter data, and performing decision feedback on the free data to improve the fading channel estimate.

Abstract: Analog correlation techniques are used in a digital receiver portion of a spread spectrum transceiver to determine when to turn ON given digital receiver components. According to a particular embodiment, an analog correlator receives the down-converted in-phase and quadrature-phase outputs from the radio section and determines when a received signal is coming up at or near a given noise level. A control circuit is coupled to the correlator to selectively activate flash A/D converters in the digital receiver portion of the baseband processor. The analog correlator replaces the RSSI for “sniffing” whether a received signal is present.

Abstract: A system and method for enabling a transmitter employing signal spreading techniques to increase the data rate of the transmitted modulated signal without reducing the multi-path delay spread. Specifically, the system and method use concatenated spreading sequences to provide data modulated spread signals having increased data rates with extended multi-path delay spread. The system and method therefore removes the one-to-one relationship between the repetitive spreading code length and maximum multi-path delay spread of a data modulated spread signal, to thus increase the data rate for a given multi-path delay spread while preserving the autocorrelation and cross-correlation properties of the individual spreading sequences.

Abstract: A direct sequence spread spectrum receiver for use in a communication system that utilizes code shift keying (CSK) modulation. Code shift keying modulation transmits data in the form of circularly rotated spreading waveforms such as PN sequences. The data is conveyed in the amount of rotation applied to the spreading waveform before it is transmitted. While tracking, the receiver decodes the received symbols yielding the original transmitted data. The input frequency range of the receiver is divided into one or more frequency bands. For each frequency band, the received signal is filtered, digitized and split into I and Q data streams wherein the Q data stream is delayed by ¼ƒc. Both I and Q data streams are sampled and correlated with an adaptive template. The received data is clocked into a shift register and circularly rotated and a correlation sum is generated. The correlation output of both I and Q channels are summed over all the frequency bands and a maximum correlations is determined.

Abstract: A PN sequence output apparatus outputs a PN sequence which is generated by using a Chebyshev polynomial T(a, cos &thgr;)=cos(a &thgr;) for an integer a (2≦a) and which has a length N (1≦N). An accepting section accepts an S (1≦S) number of initial values X1, X2, . . . , Xs each of which is a real number larger than −1 and less than 1, and an S number of degrees p1, p2, . . . , ps each of which is an integral number equal to or larger than 2. A calculation section calculates a Pseudorandom Noise sequence, having a length N, z[1], z[2], . . . , z[N], using the initial values, the degrees, and recurrence formulas xj[1]=Xj, xj[m+1]=T (pj, xj[m]), and z[n]=Πj=1s T(pj, xj[n]), for integers j (1≦j≦S), m (1≦m≦N−1) and n (1≦n≦N). An output section outputs a PN sequence.

Abstract: A device for carrying out search procedures includes a memory for storing a digital received data sequence, and a memory storing a predetermined correlation data sequence. A correlation device has a first section, in which sequence elements of the received data sequence are correlated with sequence elements of the correlation data sequence. A variable number K of sequence element correlation results are summed in the second section, in order to form an accumulated correlation result.

Abstract: The present invention reduces the scale of circuitry and shortens the code phase detection time needed to achieve initial synchronization. In a correlator for calculating correlation between a received spreading code contained in a received spread-spectrum signal and a reference spreading code, a combined code generator is included. The combined code generator outputs a combined spreading code by weighting and combining a plurality of phase-shifted reference spreading codes A1-AM. Further, an arithmetic circuit calculates correlation between the received spreading code and the plurality of phase-shifted reference spreading codes simultaneously. A phase detection circuit detects the phase difference between the received spreading code and a reference spreading code, namely the phase of the received spreading code from the results of the arithmetic operation.

Abstract: A method and device for determining a frame rate of a data fame transmitted over a variable rate communication system. In one embodiment, the present invention receives demodulated soft symbols representing a data frame transmitted at a certain frame rate. The present invention then generates a plurality of decoded bit streams from the demodulated soft symbols, where each of the plurality of decoded bit streams is for testing one of a plurality of rate hypotheses for the frame rate of the data frame. The present invention next re-encodes each of the plurality of decoded bit streams to generate a plurality of re-encoded bit streams, each of which corresponds to a plurality of decoded bit streams.

Abstract: A receiver for use in a spread spectrum communication system includes the following components: an acquisition system configured to detect a transmitted spread spectrum signal by simultaneously correlating multiple search phases of a reference spreading signal against an output from a receiver channel; a demodulation system configured to recover data embedded in the spread spectrum signal by simultaneously correlating the spread spectrum signal with multiple possible data phases of the reference spreading signal over consecutive data periods; and a bank of correlating devices configured for use both in the acquisition system and in the demodulation system.

Abstract: Methods and systems for time synchronizing a receiver to a spread spectrum signal are described. Exemplary embodiments of the present invention provide for at least a two step process in which, at a first step, a number of candidate synchronization frequencies or timings are identified, followed by confirming one of the candidates as a correct synchronization state at a second or final step. According to the present invention, the confirmation step may be performed at the same time as the step of identifying further candidates by processing the same received signal samples in different ways.

Abstract: A civil moderate (CM) code and a civil long (CL) code are time division multiplex (TDM) as a combined code having alternating code chips that spectrum spread a transmitted signal received by a receiver tracking the spectrum spreading code using a two-level correlator operating with +1 and −1 values to alternately correlate the received CM and CL code chips using a gating signal to gate by time the correlation of the two codes. The time gated two-level TDM correlation can be used in communication receivers, such as GPS receivers, receiving the TDM spectrum spreading codes.

Abstract: A method allows determination of the presence of, the frequency of, and or the timing of a coded signal distributed in time, as for example a direct-sequence spread-spectrum signal or a signal having a coded header. According to the method, the received signal is correlated (16, 216, 316) with small sections of the spreading or header code, to produce partial correlations, as for example a 1024-chip spreading code is correlated in eight- or sixteen-chip portions. The result of each partial correlation is delayed (32, 232, 332/350) by an amount which results in temporal congruence or simultaneous occurrence of the partial correlations at a Doppler processor. The processor processes the simultaneous partial correlations, to produce signals which recur in the appropriate frequency bin at the recurrence rate of the spreading code. The frequency bin identifies the frequency of the received signals, and the time of the appearance of the signals at the bins is indicative of the time.

Abstract: A method and apparatus for receiving orthogonal signals in a spread-spectrum communications system. A demodulator provides groups of de-spread samples of a processed received signal. The groups of de-spread samples are passed through an orthogonal code transformer to provide sequential transformer blocks. The blocks are buffered in sequences of 2 or 3. Then each buffered sequence is subjected to a summing, squaring and selection operation a to obtain a desired orthogonal code from each of the transformer blocks of the two or three transformer blocks.

Abstract: An assembly of simultaneously transmitted electrically generated signals is disclosed, which contains a subset of binary spreading-code sequences that are members of a larger set of binary spreading-code sequences available to a particular node of a multi-node communication network. All sequences in the set of spreading-code sequences available to the particular node of the network can be generated by the same configuration of two linear-feedback binary shift registers, where feedback taps of the two linear-feedback binary shift registers correspond to primative polynomials of the same degree over GF(2), the field of two elements.

Abstract: The invention relates to systems and methods for receiving signals modulated with a carrier frequency, wherein the signals include spreading chip sequences having at least one zero. The invention includes a method of receiving and despreading spread spectrum signals wherein the spread spectrum signals include spreading chip sequences having at least one zero and at least one non-zero chip. The method includes receiving and sampling a spread spectrum communication signal. The receiver generates a despreading code which is synchronized with the sampled spread spectrum communication signal. The sampled spread spectrum communication signal is then despread with the despreading code by omitting at least one operation involving at least one zero chip. The invention further includes a receiver configured to receive signals modulated with a carrier frequency over a channel, wherein the signals include spreading chip sequences having at least one zero.

Abstract: A communications acquisition method includes a correlation of a received, coded spread sequence having a length of m bits with a locally generated spread sequence m times, in each case delayed by one bit, in order to form m correlation responses. Each correlation response is added, with a delay, to a succeeding correlation response to form a correlation result, the delay being an integer multiple of m and of a further bit. Finally, a maximum search is carried out over all m correlation results. A configuration for carrying out the method includes a correlator having an output connected to a first input of an adder and also to a second input of the adder through a delay element.

Abstract: CDMA radio-communications procedure with access codes and pertinent receiver.

Abstract: A method and apparatus for computing a convolution between an input GPS signal and a C/A code reference by generating the convolution result in real time without storing unprocessed signal samples. The apparatus comprises a vector multiplier running at high speed to achieve the same result as a vector multiplier sized to process an entire epoch.

Abstract: Embodiments of the invention are used to improve performance of spread spectrum communications equipment. The improvement may take the form of improved sensitivity to weak signals, quicker acquisition time of weak signals, or the reduction of multipath interference. To acquire a spread spectrum signal PN codes are commonly compared with the spread spectrum signal. This comparison is often in reality a successive series of comparisons with the same code. Successive comparisons are often carried out in a process called hypothesis testing by which the correlated output of the spread spectrum signal and the PN code must pass a series of thresholds. This method is adopted to prevent identifying a PN code as being present based on a spurious correlation value. This method of successive comparisons also prevents a low correlated value from being rejected immediately thereby helping assure that signals with low signal strength can be identified also.

Abstract: Received quality detecting section 108 detects a received quality, bit determining section 111 determines whether a TPC bit is 0 or 1, amplitude reading section 112 reads a ratio of an amplitude of a signal other than the TPC bit and an amplitude of the TPC bit, accumulating section 113 determines an increase or decrease of transmit power and an amount of the increase and decrease of the transmit power using a symbol of the TPC bit for the increase or decrease, and an amplitude ratio for the amount of the increase and decrease to instruct to transmission amplifier 104, and multiplying section 114 multiplies the amplitude of the signal other than the TPC bit by a correction value corresponding to the received quality to determine the amplitude of the TPC bit.

Abstract: A Global Positioning System receiver includes an intermediate frequency (IF) processor configured to downconvert broadcast signal to generate a first channel signal which is further downconverted to recover a PRN signal by an angle rotator. The receiver further includes a signal generator configured to generate N gated PRN signals. The N gated PRN signals are generated based on a local replica PRN signal time-divided by M intervals within a chip period of the local replica PRN signal. N and M are positive integers. A number of correlators is also provided. Each of which the correlators are configured to multiply a respective one of N gated PRN signals with the PRN signal to generate a number of correlation values. The correlation values are utilized to monitor distortions in the broadcast signal and/or to track the carrier frequency signal. Further, a corresponding method is also provided.

Abstract: A receiver for detecting spread spectrum binary data particularly on a power line in the presence of channel distortion. In one embodiment a standard pattern ideally suited for minimal distortion in the channel is used in conjunction with an alternate pattern which is developed to better detect carrier and data in the presence of certain channel distortion. The receiver switches between the standard and alternate pattern to provide improved detection. In another embodiment an adaptive pattern is used which is developed from the receive signal. For instance, the signal over several bit times is averaged to provide a pattern which is correlated with a receive signal.

Abstract: A receiver including an apparatus for generating complex four-phase pseudo-random code sequences which may be directly mapped to a quadrature phase shift keying (QPSK) signal constellation. The apparatus includes a shift register coupled to an accumulator, which combines the output of the shift register with a predefined value and inputs the result back into the accumulator. Certain bits are extracted form the shift register and are used to generate the code sequences.

Abstract: A correlation function measuring method and apparatus can correct a correlation vector with high accuracy. The correlation function measuring apparatus includes first signal processing means 18a to 22a for processing a first monitored signal to give a first spectrum, second signal processing means 18b to 22b for processing a second monitored signal to give a second spectrum, correction value computing means 26 for inputting correction signals to the first and second signal processing means to give correction values corresponding to respective frequencies, based on the first spectrum and the second spectrum, and correlation function computing means 30 for obtaining a correlation function between the first spectrum and the second spectrum by using correction values given by the correction value computing means.

Abstract: A cellar system using code divisional multiple access (CDMA) system is disclosed, that comprises a plurality of finger circuits, and a search engine portion having a reception level measuring portion for detecting reception levels from reception signals and comparing the reception levels with a predetermined threshold value, a plurality of inversely spreading portions for multiplying the reception signals by spread codes, an inner memory for storing correlation signals received from the plurality of inversely spreading portions, and a reception path timing generating portion for detecting reception paths from output signals of the inner memory and, generating a path timing, wherein the search engine portion determines whether or not to output a correlation signal of the inner memory to the reception path timing generating portion.

Abstract: A receiver of a handset transceiver, in a wireless telephone system having a plurality of wireless handset and a base unit having a base transceiver. Each handset has a handset transceiver for establishing a time-division multiple access (TDMA) link over a shared channel with the base unit via the base transceiver, in which each handset communicates during an exclusive time slot of a TDMA scheme that allocates time slots to handsets during an exclusive time slot of a TDMA scheme that allocates time slots to active handsets for receiving a spread spectrum signal comprising successive chips representing successive symbols. Each receiver has one or more demodulation loops for demodulating the received spread spectrum signal, wherein each demodulation loop is characterized by one or more demodulation loop parameters. A parallel correlator of the receiver detects a peak bin and provides the peak bin and two adjacent bins.

Abstract: A method and apparatus for improving bit error performance within a hard decision radio interface processing environment is provided, whereby a sampling unit collects a number of samples per channel symbol of an input signal to generate a number of sampling streams, and a correlator computes a correlation value of each of the number of sampling streams with a predetermined bit sequence. The correlation values are fed into a threshold comparator which utilizes a variable threshold value to generate threshold comparator values or trigger output values. By examining a set of trigger output values, a phase decision unit determines the optimum sampling timing or sampling phase.

Abstract: In a matched filter, a spread data path unit holds inputted spread data, a multiplier unit multiplies an output of the spread data path unit by a spreading replica code, and an adder unit adds results of the multiplication and outputs an added result. The spread data path unit comprises a first selector being able to selectively output the spread data, a plurality of sub spread data path units each having a plurality of latch circuits temporarily holding the spread data from the first selector, and a second selector being able to selectively output outputs from the sub spread data path units, whereby a circuit scale of the spread data path unit is decreased.

Abstract: A method and apparatus for DS-CDMA communication having improved timing resolution. In the transmitter, a signal spread by a first sequence of pulses is generated with pulse shape given by p ⁡ ( t T c ) , where t is time and Tc is the chip period or pulse width. The pulses have an auto-correlation function q ⁡ ( t T c ) . In receiver, a second sequence of pulses with pulse shape given by p ⁡ ( t T c ) is generated.

Abstract: The number of users and data capacity of wireless systems are increased by employing apparatus and method for increasing the number of spreading codes available in the system by providing a mechanism to reuse the already allocated spreading code or use the codes that may correlate to those already being used within the same sector/cell. This, in return, provides capacity improvement proportional to the number of added base station (BS) antennas for each cell. An antenna null steering technique for code allocation maintains the cross correlation properties of the codes only for the desired user and to obtain a gain in capacity improvement.