Abstract: A spread-spectrum receiver for time sharing a correlator for simultaneously receiving a plurality of parallel spread-spectrum signals. A combined multiplicity of symbols includes a multiplicity of symbols, simultaneously occurring during a symbol-time duration, from a plurality of spread-spectrum signals. A demultiplexer demultiplexes a sequence of the combined multiplicity of symbols into a plurality of symbol registers. Each of the symbol registers stores the chip-sequence signals corresponding to the combined multiplicity of symbols which were sent to the particular symbol register. A multiplexer selects a symbol register, other than the symbol register selected by the demultiplexer. The multiplicity of chip-sequence signals stored in the selected symbol register by the multiplexer are compared by a comparator with a multiplicity of replicas of the chip-sequence signals used to generate the spread-spectrum signals.

Abstract: A system and method using a Costas loop to effect accelerated convergence with minimal system complexity. The system comprises an in-phase-limiter and a quadrature-phase limiter, operatively coupled to an EXCLUSIVE-OR gate, for exclusively-ORing an in-phase-sign signal and a quadrature-phase-sign signal to output a first error signal, responsive to the signals having same signs, or a second error signal, responsive to the signals having different signs. An AGC circuit, operatively coupled to an output of the EXCLUSIVE-OR gate, increases and decreases a voltage level of an AGC signal responsive to two consecutive first or second error signals and consecutive dissimilar error signals, respectively. A voltage-controlled oscillator, operatively coupled to an output of the AGC circuit and responsive to the increased or decreased voltage level, changes the frequency of a voltage-controlled-oscillator output signal.

Abstract: A system for maintaining orthogonality among a plurality of spread-spectrum signals arriving at a base station from a plurality of remote units. Each spread-spectrum signal of the plurality of spread-spectrum signals from each remote unit of the plurality of remote units is transmitted as a packet having a header followed by data. A base station sends a plurality of adjustment signals over a communications channel to the plurality of remote units, respectively. At each remote unit, a circuit selects, from the plurality of adjustment signals, a received-adjustment signal designated for each remote unit. A chip-sequence generator, located at each remote unit, generates a chip-sequence signal assigned to a respective remote unit and, responsive to the adjustment signal, adjusts timing of a chip-sequence signal generated by the chip-sequence generator.

Abstract: A system and method for W-CDMA transmissions from the base to a remote unit and spread-TDMA transmissions from the remote unit to the base. By using spread-TDMA on the reverse link, limitations inherent with the use of CDMA due to non-zero cross correlation are avoided. The resulting system provides high quality performance in both directions.

Abstract: A multichannel-spread-spectrum system for communicating a plurality of data-sequence signals from a plurality of data channels using parallel chip-sequence signals in which fewer than all of the channels include header information. A header device concatenates a header to a first data-sequence signal on a first channel. Data-sequence signals in parallel channels are sent without a header, and are timed from the header in the first channel.

Abstract: A system and method for encoding and transmitting data with a spread-spectrum packet-switched system. Data to be transmitted by a packet transmitter are encoded for privacy and to restrict intelligent receipt of the data to the intended recipient. The encoded data is demultiplexed into sub-data-sequence signals which are spread-spectrum processed and then combined as a multichannel spread-spectrum signal. The multichannel spread-spectrum signal is concatenated with a header to output a packet-spread-spectrum signal which is transmitted over radio waves to a packet receiver. The packet receiver obtains timing for the multichannel spread-spectrum signal from the header. The multichannel spread-spectrum signal is then despread and multiplexed as received-encoded data. The received-encoded data is decoded by the intended recipient and is stored in a receiver memory for output.

Abstract: A multi-clock matched filter for receiving signals with multipath. The signals may be modulated with a spread-spectrum spreading sequence, or other analog or digital signal. A number of signal registers store digital samples of the received signal. The gating of digital samples into each of the signal registers is controlled by a separate clock timing. The timing sequence may be derived from a common clock. A multiplexer sequentially selects each of the signal registers, and passes the respective content of each signal register to a matched filter. A number of delay-locked-loop circuits track each of the multipath signals, and generate the timing sequence for gating signal registers.

Abstract: A system and method for synchronizing a Costas Loop for demodulating a received spread-spectrum signal having data and a first arbitrary phase angle, .phi.(t), using a phase detector, a phase unwrapping subsystem, an oscillator, a derotator and a decision device. A second arbitrary phase angle, .theta.(t), is generated from an in-phase component and a quadrature-phase component of the received spread-spectrum signal. The second arbitrary phase angle, .theta.(t), is proportional to the first arbitrary phase angle, .phi.(t). A value of .theta. proportional to .theta.(t) is then estimated. The estimated .theta. value is processed to obtain an estimate for the .phi.value, and a cosine and a sine of the estimated .phi. value are generated by the oscillator. The derotator derotates the in-phase-component and the quadrature-phase component of the received spread-spectrum signal with the cosine and the sine of the estimated .theta. value to generate a demodulated signal.

Abstract: An improvement to a receiver for receiving multiple rays, due to multipath, of a received spread-spectrum signal having a chip-sequence signal with a chip rate embedded therein. The received spread-spectrum signal is sampled by an analog-to-digital converter at approximately twice the chip rate and then the samples are shifted in a shift register. The shift register shifts the chips of the underlying chip-sequence signal at approximately twice the chip rate. A matched filter includes an adder tree which, in cooperation with the shift register, forms an impulse response matched to the chip-sequence signal. The adder tree detects initially the chip-sequence signal embedded in the first ray, and outputs a first correlation signal. The adder tree then detects the chip-sequence signal embedded in the second ray, and outputs a second correlation signal. The adder tree continues to detect the chip-sequence signal of subsequent rays, and outputs subsequent correlation signals.

Abstract: A intelligent power management apparatus for use with a matched-filter. A multiplexer multiplexes shifted-in-phase chips and shifted-quadrature-phase chips from an in-phase-shift register and a quadrature-phase-shift register, respectively, to generate multiplexed chips. The multiplexed chips include alternating sets of shifted-in-phase chips and shifted-quadrature-phase chips. A controller generates a POWERDOWN signal when the multiplexed chips from a received-spread-spectrum signal are unlikely to have a particular-chip sequence. The controller generates an ACTIVATION signal when the multiplexed chips are likely to have the particular-chip sequence present. An adder tree generates a CORRELATION signal when the multiplexed chips have the particular-chip sequence and match or correlate with the settings of the adder tree.

Abstract: A fuzzy-logic spread-spectrum adaptive power control system comprising a base station and a plurality of remote units. The base station receives a spread-spectrum signal, and samples the despread spread-spectrum signal at a peak correlation time of the data channel, and at a non-peak correlation time of the data channel. This in turn generates a signal level and a noise level, respectively. A signal-to-noise ratio calculator generates a signal-to-noise ratio from the signal level and the noise level. A fuzzy-logic controller compares the signal-to-noise ratio to a set of predetermined thresholds, and using a state machine, generates a control signal which is thereby transmitted to the remote unit, indicating the amount by which to increase or decrease transmitted power. Each remote unit demodulates the control signal, and a transmitter controller adjusts a power level of the remote-unit spread-spectrum transmitter.

Abstract: A system and method using a Costas loop to effect accelerated convergence with minimal system complexity. The system comprises an in-phase-limiter and a quadrature-phase limiter, operatively coupled to an EXCLUSIVE-OR gate, for exclusively-ORing an in-phase-sign signal and a quadrature-phase-sign signal to output a first error signal, responsive to the signals having same signs, or a second error signal, responsive to the signals having different signs. An AGC circuit, operatively coupled to an output of the EXCLUSIVE-OR gate, increases and decreases a voltage level of an AGC signal responsive to two consecutive first or second error signals and consecutive dissimilar error signals, respectively. A voltage-controlled oscillator, operatively coupled to an output of the AGC circuit and responsive to the increased or decreased voltage level, changes the frequency of a voltage-controlled-oscillator output signal.

Abstract: A multipath-combining subsystem for receiving a spread-spectrum signal arriving from a plurality of paths. A header-matched filter detects each match, within each path, of a header-chip-sequence signal with a first impulse response and outputs a header-detection signal having a header amplitude and a respective chip location. A data-matched filter detects at the respective chip location of each header-detection signal, a respective data-chip-sequence signal and outputs a data-detection signal having a data amplitude. A combiner multiplies the header amplitude of each header-detection signal and the data amplitude of the respective data symbol to generate a plurality of weighted elements for each data symbol. The combiner then adds the plurality of weighted elements for each data symbol as a sum signal of the respective data symbol.

Abstract: A superior and scaleable architecture for implementing a large bit matched filter. The implementation of the bit matched filter requires less silicon and consumes less power as compared to the existing design. An effective way to turn the bit matched filter on and off for power saving is also disclosed.

Abstract: A spread-spectrum-correlator apparatus including a symbol-shift register, an in-phase-symbol correlator, a quadrature-phase-symbol correlator, a frame-shift register, an in-phase-frame correlator, a quadrature-phase-frame correlator, and a control processor. The symbol-shift register circulates replicas of a header-chip-sequence signal or data-chip-sequence signal, which are used for in-phase-symbol correlating and the quadrature-phase-symbol correlating. The in-phase-frame correlator and the quadrature-phase-frame correlator detect a despread-header-symbol-sequence signal and generate a maximum output signal which may be used as a data-start signal or for synchronizing the timing of the control processor as to when to trigger sampling of the analog-to-digital converter, to set which chip-sequence signal is circulated in the symbol-shift register, to control the output of the symbol correlator, to detect the data-symbol-sequence signal and other time-dependent processes.

Abstract: A spread-spectrum-matched-filter apparatus including a code generator, an in-phase-symbol-matched filter, a quadrature-phase-symbol-matched filter, an in-phase-frame-matched filter, a quadrature-phase-frame-matched filter, and a controller. The code generator generates replicas of a chip-sequence signal, which are used to set the symbol-impulse responses of the inphase-symbol-matched filter and the quadrature-phase-symbol matched filter. The in-phase-frame-matched filter and the quadrature-phase-frame-matched filter detect a despread-header-symbol-sequence signal and generate a maximum output signal which may be used as a data-start signal or for synchronizing the timing of the controller as to when to trigger sampling of the A/D converter, the output of the symbol-matched filters, detection of the data-symbol-sequence signal and other time-dependent processes.

Abstract: In a cellular spread-spectrum communications network, a system and method for handing off a remote unit from a first base station to a second base station without loss of data. The remote unit receives a first spread-spectrum signal having a first signal quality from the first base station and transmits data to the first base station at a first data rate and a first power level. Responsive to monitoring the first signal quality and comparing the first signal quality to a plurality of signal qualities of a respective plurality of received-spread-spectrum signals, the remote unit initiates handoff when any of a number of predetermined criteria are met. Upon initiating handoff to the second base station, the remote unit stores the data that would otherwise have been transmitted.

Abstract: A spread-spectrum-matched-filter apparatus including a code generator, a programmable-matched filter, a frame-matched filter, and a controller. The code generator generates replicas of a pilot-chip-sequence signal and a data-chip-sequence signal, which are used to set the programmable-impulse response of the programmable-matched filter. The programmable-impulse response is alternately changed between that of the pilot-chip-sequence signal and the data-chip-sequence signal so that the programmable-matched filter alternately detects the pilot-spread-spectrum channel and the data-spread-spectrum channel embedded in a received spread-spectrum signal. The frame-matched filter detects a despread-pilot-bit-sequence signal and generates a peak-pilot-correlation signal which can be used for timing of the controller as to when to trigger changing the programmable-impulse response of the programmable-matched filter.

Abstract: A intelligent power management apparatus for use with a matched-filter. A multiplexer multiplexes shifted-in-phase chips and shifted-quadrature-phase chips from an in-phase-shift register and a quadrature-phase-shift register, respectively, to generate multiplexed chips. The multiplexed chips include alternating sets of shifted-in-phase chips and shifted-quadrature-phase chips. A controller generates a POWERDOWN signal when the multiplexed chips from a received-spread-spectrum signal do not have a particular-chip sequence. The controller generates an ACTIVATION signal when the multiplexed chips have the particular-chip sequence present. An adder tree generates a CORRELATION signal when the multiplexed chips have the particular-chip sequence and match or correlate with the settings of the adder tree. A number of AND gates inhibit the multiplexed chips from passing to the adder tree when the POWERDOWN signal is present, and pass the multiplexed chips to the adder tree when the ACTIVATION signal is present.

Abstract: A system and method for synchronizing a Costas Loop for demodulating a received spread-spectrum signal using a squaring device, a filter, a phase detector, a phase unwrapping subsystem, an oscillator, a derotator and a decision device. Phase-shift-keying modulation is removed from a received spread-spectrum signal through squaring. An in-phase component and a quadrature-phase component of the received spread-spectrum signal are filtered to generate an arbitrary phase angle, .theta.(t). A value of .theta. proportional to .theta.(t) is then estimated. The estimated .theta. value is processed to obtain an estimate for the .phi. value, and a cosine and a sine of the estimated .phi. value are generated by the oscillator. The derotator derotates the in-phase-component and the quadrature-phase component of the received spread-spectrum signal with the cosine and the sine of the estimated .theta. value to generate a demodulated signal. The decision device evaluates the demodulated signal and outputs data.