Abstract: A system and method for detecting signals. A system includes a first antenna configured to receive at least a first input signal and generate at least a first received signal, and a second antenna configured to receive at least a second input signal and generate at least a second received signal. Additionally, the system includes a receiver system configured to generate at least a first output signal, a second output signal, a third output signal, and a fourth output signal. Moreover, the system includes a correlation system configured to receive at least the third output signal and the fourth output signal and generate at least a correlation signal, and a processing system configured to estimate a cross correlated power level.

Abstract: A method of path gain estimation for a downlink WCDMA system. The present invention further provides a system for realizing the path gain estimation method. A transmitting device of the system comprises a first and a second antenna to transmit signals with the space time transmit diversity (STTD) scheme. The first and second antennas transmit common pilot channel (CPICH) symbols that are orthogonal to each other, and the CPICH symbols are received by a single antenna of a receiving device. The receiving device then determines the path gain by a STTD filter coefficient determination process, which includes a block selection process for selecting a combination of the CPICH symbol and a tap gain determination process for determining equations for estimating the path gain of the system.

Abstract: A radio frequency (RF) receiver comprising: 1) a local oscillator (LO) circuit capable of receiving a local oscillator (LO) reference signal having frequency, LO, and a double sideband (DSB) clock signal having a frequency, DSB, and generating therefrom an in-phase product signal of the LO reference signal and the DSB clock signal in which a polarity of the LO reference signal is reversed at the DSB frequency of the DSB clock signal; and 2) a first radio frequency (RF) mixer having a first input port capable of receiving the in-phase product signal from the LO circuit and a second input port capable of receiving a modulated radio frequency (RF) signal, wherein the first RF mixer generates a first downconverted output signal.

Abstract: Methods and apparatus for allocating tones for communications purposes in adjoining cells of an OFDM system are described. Tones used in each cell are allocated to tone hopping sequences according to a tone to tone hopping sequence allocation function. Different cells use different tone to tone hopping sequence allocation functions to minimize the number of collisions between hopping sequences of neighboring cells. Tone hopping sequence to communications channel allocation functions are used to allocate tone hopping sequences to communications channels. Communications channels are used by wireless terminals, e.g., mobile nodes, to transmit data. Over time, a wireless terminal uses the tones included in the tone hopping sequences corresponding to communications channels it is authorized to use. Accordingly, tones are assigned to communications devices by a multi-function, e.g., two level, mapping operation.

Abstract: A first transceiver (200) sends (102) a predetermined number of blocks of data to a second transceiver, and records (104) on which of a plurality of sub-carriers each of the blocks of data is sent. The first transceiver receives (106) from the second transceiver a list of the blocks of data that were received with errors, and calculates (108) from the list a plurality of error rates corresponding to the plurality of sub-carriers. The first transceiver then determines (110) the SQE for each of the plurality of sub-carriers from the plurality of error rates, and adjusts (112) the data rate in accordance with the SQE determined for each of the plurality of sub-carriers. These processes can be implemented as a method that is facilitated by a software program.

Abstract: A technique for generating a demodulation ordering used in receive signal processing operations in a BLAST MIMO receiver that is based on a relative comparison of near-to-far resistance measures among vectors forming the estimated channel transfer function matrix is disclosed. This near-to-far resistance comparison provides a resulting demodulation ordering believed equivalent to that provided by conventional V-BLAST techniques without requiring computation of the pseudoinverse of the estimated channel matrix. Also disclosed is a successive interference cancellation technique which employs Multi-Staged Nested Weiner Filtering (MSNWF) to recover soft estimates of the transmitted component-symbols from the vector observed at the BLAST MIMO receiver.

Abstract: The invention provides improved suppression of co-channel interference (CCI) in a wireless cellular communications system where at least two base stations use the same transmit frequency. The method according to the invention uses the difference in synchronization times between the home signal and the CCI signal to suppress the CCI signal. The method uses a modified known method of estimating time of arrival (TOA) to estimate sync positions for the CCI signal. This enables the use of interference cancelling methods in communications systems using un-synchronized base stations. Receiver performance is improved, which in turn improves data throughput and received speech quality, since interfering signals from base stations using the same frequency can be suppressed.

Abstract: The invention relates to a code-tracking method and a rake receiver for CDMA communication systems of low complexity yielding stable tracking. Received signal are distributed to a plurality of receiver fingers of a rake receiver. Each receiver finger i is assigned to a signal path of the transmitted signal which is subject to phase shift and power dissipation due to reflection, diffraction and scattering. According to the invention in each receiver finger i an estimation of the timing delay {circumflex over (?)}(i) is provided and interference from other signal components j are subtracted from signal components of the current signal path i (i?j) yielding a reliable estimated timing delay {circumflex over (?)}.

Abstract: The invention relates to a method of estimating a downlink channel in a radio system, and to a radio system. The method includes transmitting a common pilot signal and a user-specific pilot signal, of which channel estimates are formed. A channel estimate for the user-specific channel that has transmitted the user-specific pilot signal is formed of said channel estimates by selecting an appropriate scaling factor. The quality of the user-specific channel estimation and thus also the performance of the radio system are improved by the invention.

Abstract: A method of splitting a signal (10) into two parts (10?, 10?) is disclosed together with signal processing circuitry (22) for the same. The method comprises the steps of derotating the signal (10) whereby the frequency band of the derotated signal overlaps zero frequency; and splitting the derotated signal into two parts, a first signal part (10?) consisting substantially of positive frequency signal components and a second signal part (10?) consisting substantially of negative frequency signal components. Also disclosed is methods, incorporating such a method of splitting a signal, for identifying the presence of in-band interference (11) in a signal and for despreading a spread spectrum signal.

Abstract: A complementary code keying (CCK) demodulator used in a RAKE receiver receiving CCK symbols in a multipath environment computes multipath interferences (MPIs) required for canceling intra-codeword chip interference (ICI). The algorithmic structure jointly computes the ICI of a plurality of possible codewords. The algorithmic structure is similar to the optimal architecture required for CCK correlation computations. The similarity between these two structures allows for the use of the same hardware at different times to compute MPIs and to compute the CCK correlation of a plurality of possible codewords.

Abstract: Successive interference canceling for CMDA. ICI may result from a signal's multipath effects, or by filtering/suppression of some of the component energy of the signaling waveforms. Energy component attenuation destroys orthogonality of CDMA symbols thereby causing ICI. An ICF suppresses frequency domain portions (attenuates ingress), but also introduces ICI. Following the ICF, the signal is de-spread, sliced, re-spread and convolved with the ICF echoes (except first tap echoes). Convolving re-spread hard decisions with delayed ICF taps is equivalent to partially re-modulating the first-pass hard decisions to efficiently “add-back-in” the signal energy which was blanked/subtracted by the ICF. Alternatively, parameter estimation de-rotates and re-rotates soft symbols and hard decisions, respectively, compensating for undesirable symbol rotation. The convolved signal is subtracted from a delayed version of the ICF output signal.

Abstract: Crosstalk can be cancelled in a composite communication signal (ym) which includes a primary signal component associated with communication data and which also includes a crosstalk signal component produced by applying a crosstalk coupling function to crosstalk data. An estimate (R, RCb(0), RCb(?f)AVG) of a statistical characteristic of the crosstalk signal component is obtained from the composite communication signal. A cancellation signal (26, 46) is generated based on the statistical characteristic estimate, and an estimate (29) of the communication data is produced based on the composite communication signal and the cancellation signal.

Abstract: A decorrelating rake receiver (401) using a signal processor (213) and corresponding method (1000) to determine filter coefficients (1005). The decorrelating rake receiver includes a plurality of filters (219) arranged to be coupled to an input signal (403) and the filter coefficients (409), the plurality of filters operable to provide a plurality of output signals and a coefficient generator (407), coupled to the input signal, to explicitly and definitely determine the filter coefficients for the plurality of filters such that the plurality of filters perform a decorrelating rake process. The decorrelating rake receiver further includes a combiner (221) to combine the plurality of output signals and provide a received signal (405). The decorrelating rake receiver (401) is suitable for use in a wireless communication device (101) or base transceiver (103).

Abstract: A demodulator of a W-CDMA base station comprises: a chip calculator for de-spreading signals received through sectors including antennas; a symbol calculator for using symbols of a control channel and a data channel from the de-spread signals, estimating a channel, and combining signals input through a multi-path; a frame calculator for combining the combined signals to perform transport format combination indicator decoding, feedback information decoding, frame sync estimation, SNR estimation, post-combining, and second de-interleaving; a storage unit for storing outputs of the chip calculator, symbol calculator, and frame calculator; a storage unit controller for controlling inputs/outputs between the chip calculator, symbol calculator, frame calculator, and storage unit; and a host interface for controlling inputs/outputs between the chip calculator, symbol calculator, frame calculator, and host.

Abstract: A method and apparatus for acquiring time and frequency synchronization in a DSSS receiver are disclosed. An iterative approach is used in acquiring a DSSS signal when the phase coherency of the signal is less than the symbol length.

Abstract: The present invention provides a synchronous demodulation apparatus of a base transceiver station in an Interim Standard-2000 (IS-2000) system, including a first synchronous demodulation unit, a received signal delay unit, an interference signal regeneration unit and a second synchronous demodulation unit. In comparison with an asynchronous demodulation apparatus used in an Interim Standard-95 (IS-95), it is possible for the inventive apparatus to improve a reception function approximately 3dB and ultimately increase the number of subscribers.

Abstract: The invention relates to a channel estimation algorithm is proposed for a RAKE receiver for CDMA communication systems operating in the downlink of a mobile communication scenario yielding an improved phasor estimation. Received signals are distributed to a plurality of receiver fingers of a RAKE receiver. Each receiver finger i is assigned to a signal path of the transmitted signal which is subject to phase shift and power dissipation due to reflection, diffraction and scattering. According to the invention the approach partly cancels multipath/multiuser interference and offers the advantage of being able to cope with physically closely spaced multipaths.

Abstract: A hybrid beamforming apparatus and method are proposed for a communication system. The hybrid beamforming apparatus includes a plurality of antennas, a plurality of FFT, a plurality of hybrid weight-coefficient generators and a plurality of adders. In each of the hybrid weight-coefficient generators, the weight coefficient for each subcarrier is calculated by a time-domain correlation matrix and a cross-correlation vector, which is calculated by a frequency domain signal and a training signal. The hybrid beamforming apparatus and method according to the present invention can enhance immunity for multipath effect with lower system complexity.

Abstract: Multiple Steiner codes are transmitted as bursts from multiple base stations (182, 184, 186) having one or more transmit elements (174, 176, 178, 180), with successive bursts providing an extended training sequence for use in channel estimation at an addressed unit (172), such as a mobile handset. Accurate channel estimation is possible through the use of Wiener frequency domain MMSE deconvolution (518) combined with frequency domain spatial decoupling matrices, with quasi-orthogonal pseudo-noise sequences (502, 504, 520, 522) allocated to base stations and their antenna elements. The use of Steiner codes to supplement Wiener frequency domain MMSE deconvolution and frequency domain spatial decoupling results in the possibility of allocating only a single training sequence to each base station provided that the training sequence is of sufficient length to encompass all multiple time-translated channel impulse responses (H).

Abstract: A Signal-to-interference ratio (SIR) measuring apparatus in a multiple antenna high data rate packet transmission system measures signal energy to interference energy ratio by using pilot signals that are orthogonal to each other between antennas signals and used by a receiver for separating the signals transmitted from all of the transmitting antennas from each other. The SIR measuring apparatus comprises a signal energy measuring unit, an interference energy measuring unit and a SIR measuring unit. The signal energy measuring unit measures signal energy by synthesizing after coherently integrating and non-coherently integrating values that are obtained by correlating a received signal with pilot patterns equal to the pilot patterns of transmitted antenna signals, respectively.

Abstract: When once determined to be free of any demodulation error by an interference removing unit provided user by user, a replica signal calculated by the interference removing unit is subtracted from an input signal vector, and a calculated user signal is output as it is as a final user signal. When it is determined by the interference removing unit that there is a demodulation error, the user signal is again calculated by the interference removing unit of an interference canceller of a next stage. As subtraction of the replica signal corresponding to the user signal having a demodulation error from the input signal vector is inhibited, precision of the interference wave removal can be improved.

Abstract: A receiver for detecting and recovering data from received data bearing radio signal samples comprises first and second detecting processors.

Abstract: The present invention provides a technique for cancellation of jammer signals in a radio frequency receiver. A radio frequency signal contains both a desirable signal and an undesirable jammer signal. The combined signal is processed with a filter (104) to extract only the undesirable jammer signal. The jammer signal is then added (104) back to the combined signal to effectively cancel the jammer signal. The system may be implemented using a feedforward approach or a feedback approach. The resultant clean signal is processed in a conventional manner.

Abstract: The invention provides improved CDMA, WCDMA (UTMS) or other spread spectrum communication systems of the type that processes one or more spread-spectrum waveforms, each representative of a waveform received from a respective user (or other transmitting device). The improvement is characterized by a first logic element that generates a residual composite spread-spectrum waveform as a function of an arithmetic difference between a composite spread-spectrum waveform for all users (or other transmitters) and an estimated spread-spectrum waveform for each user. It is further characterized by one or more second logic elements that generate, for at least a selected user (or other transmitter), a refined spread-spectrum waveform as a function of a sum of the residual composite spread-spectrum waveform and the estimated spread-spectrum waveform for that user.

Abstract: An adaptive interference suppression receiver for a DS/CDMA system includes: input signal generators outputting a part of received signals of receiver antennas that has a coding block's transfer code; adaptive filter blocks filtering a complex signal output from the input signal generators with a tap weight updated based on a constraint MMSE criterion and estimating phase and amplitude components of a specific user channel using the filtering output signal to generate a channel-estimated signal; a signal restorer combining the channel-estimated signal and the filtering output signal and restoring an original signal; a signal selector for selecting known training data signal or the restored signal; and error generators comparing the channel-estimated signal and the filtering output signal and calculating an error between the two signals.

Abstract: A path detection apparatus for use in a CDMA reception device includes: storage means for storing a delay profile; and path detection means for detecting a path by reading the delay profile from the storage means, and performing a rake-combining process based on the read delay profile. With the configuration, the path detection means includes: reference path detection means for detecting a reference path for detection of a probable path based on the delay profile read by the storage means; and detection means for detecting as a probable path in the rake-combining process a path existing in a path detecting time in which reception characteristic of the CDMA reception device can be improved from the detecting time of the reference path detected by the reference path detection means.

Abstract: A peak cancellation apparatus is included in a base station transmission unit to cancel the peak component of the peak signal. Thus, the base station transmission unit can be implemented with a lower capacity power amplifier. In addition, an existing power amplifier can be replaced with a low-priced power amplifier, so that an expense can be reduced. Moreover, since only the digital signal having the limited PAR is used, the degradation of the signal quality caused in conversion of the digital signal to the analog signal can be prevented. The peak cancellation apparatus includes a peak cancellation unit positioned between a multiplier and a pulse shaping filter or between the pulse shaping filter and a D/A converter and removing a peak component of the peak signal.

Abstract: A novel and improved method for performing paging is described. In one embodiment of the invention a searcher is used to detect spread spectrum signals. Samples received RF signals are stored in a sample buffer. During standby mode, the samples are gathered during paging slots assigned to the mobile. A set of searches are performed on the samples, and if pilot signals are detected additional demodulation is performed to detect paging messages. The resulting set of demodulation data may be combined to increase detection. After a page message has been detected, additional demodulation resources may be activated to processes more complete page messages, or other information channels. In one embodiment of the invention, the searcher includes a demodulator to perform quick page detection without the use of finger elements to reduce idle mode power consumption.

Abstract: In code division multiple access communications wherein a plurality of data streams carrying a plurality of transmit symbols are spread by a plurality of assigned spread code, the data streams are divided into a plurality of data blocks and a plurality of prefixes in symbol-level are added to the data blocks prior to the data streams being spread and combined for transmission. At the receive side, the prefixes are removed from the received data stream in the time domain and the prefix-removed data stream is converted into a transformed signal in the frequency domain. A feed-forward filter is used to implement a joint equalization and despreading operation by element-by-element multiplications in frequency domain. A feedback filter is used to remove the inter-symbol interference and update the feed-forward filter through a feedback loop.

Abstract: A relatively straight-forward implemented, and computationally efficient approach of selecting a predetermined number of unused codes is used to perform weighted linear combination selectively with each of the input spread signals in a multiple access communication system. If desired, the predetermined number of unused codes is always the same in each implementation. Alternatively, the predetermined number of unused codes are selected from within a reordered code matrix using knowledge that is shared between the two ends of a communication system, such as between the CMs and a CMTS. While the context of an S-CDMA communication system having CMs and a CMTS is used, the solution is generally applicable to any communication system that seeks to cancel narrowband interference. Several embodiments are also described that show the generic applicability of the solution across a wide variety of systems.

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 procesing element produces estimates of the user transmitted symbols as a function of the R-matrix.

Abstract: The present invention discloses a method for searching multipaths of a mobile communication system, which includes the steps of: performing a coherent detection on a reversed I and Q channel signals of a DPCCH transmitted form a mobile station, multiplying the detected signal by a pilot pattern to accumulate a pilot symbol section in a corresponding section, and performing a coherent accumulation on the other symbol section in a symbol basis; calculating energy value for each coherently accumulated I and Q channel signals; multiplying the calculated energy values by a weight that has been multiplied by the pilot symbol section and another weight that has been multiplied by the other symbol section, respectively; noncoherently accumulating the energy values multiplied by variable weights, and saving the energy values; comparing the saved energy values with a periodically designated threshold; and searching timing information as many as a number of fingers in order of highest energy value according to the compa

Abstract: A method of communications channel coding gain optimization using combined ISI cancellation and turbo decoding is provided. Log-likelihood ratio probabilities with extrinsic values are computed from previous iterations of turbo decoding and used to compute the soft-decision values of channel symbols. The soft-decision values are then used to perform intersymbol interference cancellation and generate refined channel log-likelihood ratio probabilities for the next iteration of turbo decoding.

Abstract: An adaptive antenna reception apparatus includes a multi-beam former (1) provided in common to users, to convert antenna-corresponding spread signals received by antennas of an array antenna into beam-corresponding spread signals. A receiving and demodulating section (2) is provided for one of the users, generates beam-corresponding correlation signals at a path timing from the beam-corresponding spread signals, and generates path signals by weighting the beam-corresponding correlation signals with adaptive weights which are updated adaptively, and produces a demodulation signal for the one user by combining the path signals.

Abstract: The invention relates to a method of estimating a propagation channel, between a source transmitting data and a receiver, using at least one learning sequence which comprises symbols referred to as “pilot symbols” and which is known to the receiver, so as to decode a data signal (digital signal), the signals being sent in successive frames, each frame being partitioned into a specified number of time slots. It comprises at least the following steps: a) choosing a search window, estimating the complex amplitude and the energy of each predominant path k situated in the search window over the duration of each of the time slots and demodulating the data bits (useful bits), b) updating the energy of each possible path of the search window every K slots, c) selecting every K*L slots, the energy paths k which are predominant. d) Application to the demodulation of a signal of CDMA type, or of UMTS type.

Abstract: The method of interference cancellation in a CDMA wireless communication system comprises receiving an incident digital signal containing a user signal transmitted on a CDMA user physical channel and an interfering signal, projecting said incident digital signal onto a projection space orthogonal to the space containing said interfering signal, filtering said projected signal with a filter matched to the CDMA user physical channel for detecting the data contained in said user signal.

Abstract: The present invention relates to an orthogonal spreading code in a code division multiple access (CDMA) mobile communication system, and more particularly, to a method for generating and allocating code or code pairs on the basis of an orthogonal code set, which is generated using orthogonal spreading codes, so as to reduce a peak-to-average power ratio and enlarge the length of an interference free window. In accordance with the invention, at least one orthogonal code set is generated based upon orthogonal spreading codes, one of the at least one orthogonal code set is determined as a representative orthogonal code set, and then the order is allocated according to rules determined based upon the representative orthogonal code set. The codes or code pairs are generated and allocated using the orthogonal spreading codes, so as to reduce a Peak-to-Average Power Ratio or extend the length of an interference free window (IFW).

Abstract: A method for parallel type interference cancellation in a CDMA receiver, wherein minimum processing delay time is required while ensuring performance of an interference cancellation device, and space for embedding hardware for implementing the method can be reduced. The method for parallel type interference cancellation in a CDMA receiver, comprising: (a) when an over sample position of a received signal reaches the end of a symbol of a user, completing temporary detecting and recovering the symbol of the user; (b) generating a residual signal by using the recovered signal of the user and received signal state; and (c) detecting symbol information by obtaining an interference cancelled signal by adding the residual signal to the recovered signal of the user.

Abstract: A control unit controls a 1x RAKE receiving unit to intermittently receive a paging signal transmitted from a first base station in a first cycle, in the first cycle. The control unit also controls a 1xEV-DO RAKE receiving unit to intermittently receive a paging signal transmitted from a second base station in a second cycle, in a cycle which is a multiple of natural number n of the second cycle.

Abstract: The present invention is a system and method for transmitting data symbols in a CDMA communication system including a transmitter having an antenna array and a receiver. The system generates a first and second data field of symbols, then encodes them to produce complex conjugates of the respective symbols. A first communication burst including the first and second data fields, which are separated by a midamble, over a first antenna, and a second communication burst produced using said complex conjugates of said first and second data fields, which are separated by a midamble, over a second antenna are then transmitted by the transmitter. The receiver then receives and decodes the first and second communication bursts to recover the first and second data fields.

Abstract: A Node-B/base station receiver comprises at least one antenna for receiving signals. Each finger of a pool of reconfigurable Rake fingers recovers a multipath component of a user and is assigned a code of the user, a code phase of the multipath component and an antenna of the at least one antenna. An antenna/Rake finger pool interface provides each finger of the Rake pool an output of the antenna assigned to that Rake finger. A combiner combines the recovered multipath components for a user to produce data of the user.

Abstract: A receiver, comprising a plurality of antennas configured to receive signals that are obtained by multiplying a plurality of data symbols transmitted over a plurality of data channels using spreading codes for each of the data channels, the data symbol being transmitted over a plurality of sub-carriers having different frequencies; a spreading code multiplier configured to multiply reception signals received by the plurality of antennas using spreading codes for the data channels corresponding to the reception signals; a weight controller configured to adjust antenna weights by which a reception signal received by each antenna is to be multiplied, and sub-carrier weights by which a reception signal received over each sub-carrier is to be multiplied; a weight multiplier configured to multiply the reception signals by the antenna weights and the sub-carrier weights adjusted by the weight controller; and a combining unit configured to combine the reception signals multiplied by the antenna weights and the sub-ca

Abstract: An exemplary signal processing system determines vector mismatch between a plurality of signal paths. Advantageously, the system can determine mismatch across a range of frequencies. A signal generator of the system can provide a periodic calibration signal having a plurality of frequency components. The system frequency can translate the calibration signal to provide a first set of observed samples. The first sample set can be compared to a second set of samples, which can be modeled by a function of parameters including an estimated vector mismatch and a plurality of basis functions. A value of vector mismatch can then be determined (at least to an estimate) that minimizes the difference between the first sample set and the second sample set. Methods and other systems with different advantageous configurations are also described.

Abstract: In a method for achieving higher S/N, one or more signals are received and processed to provide one or more streams of samples. In a first processing scheme, the sample stream(s) are equalized and combined within an equalizer to generate symbol estimates, which may be subsequently processed (e.g., despread and decovered) to provide a first stream of recovered symbols. The sample stream(s) may be equalized prior to being combined. In this case, each sample stream is filtered with a set of coefficients and may be scaled with a scaling factor. The scaled samples for all streams are then combined to generate the symbol estimates. Alternatively, the sample stream(s) may be combined prior to being equalized. In this case, each sample stream is scaled by a scaling factor. The scaled samples for all streams are then combined to generate summed samples that are further filtered with a set of coefficients to generate the symbol estimates.

Abstract: A system (100), receiver (160-190) and method of operation for spread OFDM wireless communication (single user OFDM-CDMA with cyclic-prefix) by: equalizing the received spread OFDM signal (y) and splitting it into first and second portions (?1, ?2); making a decision on the second portion and subtracting the second portion from the received signal to produce a first difference signal; processing the first difference signal to recover the first portion of the received signal in which symbol interfering terms of the second portion are substantially reduced; making a decision on the first portion and subtracting the first portion from the received signal to produce a second difference signal; and processing the second difference signal to recover the second portion of the received signal in which symbol interfering terms of the first portion are substantially reduced. The process may be iterated extensively at this stage.

Abstract: A received wireless signal contains a plurality of path components, each having a phase indeterminate data stream derived from an original data stream. The receiver splits the received signal into N signal copies for N raking channels, which correlate each of the N signal copies with N locally generated signals, respectively, to generate N correlated signals. Each of the N correlated signals carries an estimated phase indeterminate data stream. The raking channels then synchronize each of the correlated signals to a system clock in phase and frequency to generate N synchronized signals. The N raking channels then align the N synchronized signals to generate N aligned signals, each of which carries an aligned path data stream that is normalized in time with respect to the other aligned signals. Finally the receiver combines the aligned signals to produce an estimated original data stream.

Abstract: A communication device includes at least one of path search means for detecting respective timings of path components included a signal received via a multipath propagation path using pilot symbols of a known phase included in said received signal and channel estimation means for estimating channel variation using the pilot symbols. The path search means includes a first path search part for detecting respective timings of path components using pilot symbols and a second path search part for detecting respective timings of path components using information symbols derived from a signal demodulated according to the timings detected in the first path search part and pilot symbols. The channel estimation means includes a pilot symbol acquiring part for acquiring pilot symbols included in the received signal and a channel estimation part for implementing channel estimation using the acquired pilot symbols.

Abstract: In the hardware-efficient demodulator for a CDMA adaptive antenna array mechanism of a mobile radio communication system, a correlators bank receives digital baseband signals received through an antenna array of a base station and computes correlation values with a local code sequence. A beamformer receives the digital baseband signals and the correlation values from the correlators bank and calculates beamforming weight vectors. A searchers bank receives the digital baseband signals and calculates an initial acquisition and reliable timing information for a multipath search by a common work with the beamformer, which uses a beamforming algorithm. A beamforming complex multiplier for a finger performs a complex multiplication for the beamforming weight vectors and the digital baseband signals, and sums up them.

Abstract: A searcher for a mobile station of a cellular telephony network. Pilot signal from nearby base stations are correlated with a pseudonoise sequence inside a search window, using a bank of correlators. Each correlator is assigned a different delay, from among a sequence of delays in the window. At each delay, correlation is performed initially for a first dwell time. If the resulting correlation value exceeds a threshold, the correlation is continued for a second dwell time. Otherwise, the correlator is set to the next delay in the sequence. Only the outputs of second dwell correlations are used to identify the nearest base station. Some correlators may perform first dwell correlations at new delays in the window at the same time that other correlators are still performing second dwell correlations at old delays in the window.