International Mobile Machines Corporation

Interdigital Technology Corporation

Hughes Aircraft Company

Other

Hughes Electronics Corporation

International Mobile Machine Corporation

David N Critchlow

Karle J Johnson

Moshe Yehushua

Graham M Avis

Eric Paneth

Bruce A Smetana

Sandra J Earlam

Gregory L Westling

Wade Lyle Heimbigner

George Alan Wiley

Michael I Parr

Long Huynh

Graham N Avis

A FIR chip is used in a wireless subscriber unit. The subscriber unit includes a processor for transcoding an input signal to provide digital input symbols. A received output signal is demodulated. Digital output symbols are synthesized from the demodulated output signal processor and filtered digital input symbols are provided. An internal address decoder decodes to allow the processor to access internal functions of the FIR chip. A control and status register allows the processor to read the status of and control the internal functions of the FIR chip. A FIR filter filters the digital input symbols. A transmit timer controls timing which allows the processor to control the FIR filter. A receive timer generates timing signals for timing transcoding operations and synthesizing operations connected to the processor.

FIR chip for use in a wireless subscriber unit

A subscriber unit has a processor. The processor provides an output phase signal corresponding to a selected output digital frequency. A tuning register buffers the phase signal. A lookup table has two sets of predefined stored values pertaining to the amplitude of a signal for a single quadrant. The predefined stored values comprise coarse angle approximations and fine angle approximations. A sine and cosine generator receives the phase signal and generates sine and cosine waveforms utilizing amplitude values obtained from the lookup table. The phase signal includes phase data and specifies the quadrant and the algebraic sign of the phase data. The sine and cosine generator accessing the lookup table differently depending upon the quadrant and sine of the phase data, such that the lookup table provides an amplitude value from the sets of predefined stored values based on the phase data. A modulator combines the sine and cosine waveforms to produce the selected output digital frequency and modulates digital frequency.

Subscriber unit producing a modulated digital frequency

The present invention is a method and system for processing communication signals in a wireless telecommunication system having at least two subscriber units. The subscriber units communicate with each other through a selected band of radio frequencies over a plurality of radio frequency channels. The system generates a fixed based radio frequency signal and a digital intermediate frequency signal. The fixed based radio frequency signal and the digital intermediate frequency signal are then combined to produce a carrier signal which is communicated between the at least two subscribers.

Digital synthesizer

A subscriber unit for wireless communication with a base station in a wireless subscriber communication system includes a FIR chip, a DIF (digital intermediate frequency) chip, a single prccessor chip and a radio. The processor chip transcodes a digital voice input signal to provide digital input symbols; demodulates an output signal received from the base station to provide digital output symbols; and synthesizes a digital voice output signal from the digital output symbols. The FIR chip FIR filters the digital input symbols and generates timing signals for timing the transcoding and synthesizing operations in the processor chip. The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. The radio further processes the modulated input signal for transmission to the base station.

A subscriber unit for wireless communication with a base station in a wireless subscriber communication system includes a FIR chip, a DIF (digital intermediate frequency) chip, a single processor chip and a radio. The processor chip transcodes a digital voice input signal to provide digital input symbols; demodulates an output signal received from the base station to provide digital output symbols; and synthesizes a digital voice output signal from the digital output symbols. The FIR chip FIR filters the digital input symbols and generates timing signals for timing the transcoding and synthesizing operations in the processor chip. The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. The radio further processes the modulated input signal for transmission to the base station.

Subscriber unit for wireless digital subscriber communication system

A subscriber unit for a wireless digital telephone system is disclosed. An equalizer for receiving I and Q samples is disclosed which is in the form. The I and Q samples are complex sample pairs provided at a frequency. The equalizer receives a training signal in the form of complex I and Q sample pairs. A training signal is affected by undesirable characteristics that might be present in the I and Q samples. A comparator compares the actual input training signal with the desired output to obtain a set of weighting coefficients for the equalizer to produce the desired output. A frequency correction circuit provides a corrected frequency signal for the frequency of the sample pairs from the weighting coefficients.

Subscriber unit for wireless digital telephone system

A device and method for receiving a radio signal transmitted over a channel, selecting and deselecting an equalizer, and balancing processing in response to such selection. A radio frequency signal is received from a transmission channel into a receive path, and delay spread in the radio frequency signal is estimated using an analysis circuit. The analysis circuit also determines a threshold delay spread. In the event the estimated delay spread exceeds the threshold delay spread, an equalizer is selected, otherwise the equalizer is deselected. Similarly, in the event the estimated delay spread does not exceed the threshold delay spread, a high complexity processor is selected, otherwise a low complexity processor is selected. If the low complexity processor is selected, an output signal is generated using the low complexity processor, and if the high complexity processor is selected, the output signal is generated using the high complexity processor.

Balanced processing based on receiver selection

A digital frequency synthesizer for use in a subscriber unit of a wireless digital communication system includes a processor, for providing an output phase signal corresponding to a selected output digital frequency a storage device having predefined stored values pertaining to the amplitude of a signal for a single quadrant, and a signal generator which receives the phase signal and generates sine and cosine waveforms utilizing amplitude values obtained from the lookup tables. The signal generator accesses the storage device differently depending upon the quadrant and sign of the phase data such that the storage device provides an amplitude value from said set of values based upon the phase data.

Direct digital frequency synthesizer for use in a subscriber unit of a

A receiver designed for use in a mobile environment, which includes an adaptive equalizer driven by phase estimation and rotation circuitry, and which is operable in multipath fading channels. The present invention uses an AFC loop and a phase rotation circuit in front of the adaptive equalizer to improve equalizer performance in the fading channel. The present invention uses .pi./4 phase rotation circuitry before a phase quantization decision is made. This .pi./4 phase rotation circuitry allows for decisions to be made on a QPSK constellation, rather than on an input 8PSK constellation, thus improving detection performance.

Modem for fading digital channels affected by multipath

A mobile station cellular telephone transmitting system having a digital data source, waveform map, FIR filter with eight taps, a zero force circuit, start/end burst detection circuit, quadrature modulator, upconverter, and power amplifier. The ramping of the power output at the beginning and end of each frame slot or burst is controlled by forcing the first and last symbol of the burst's FIR filter output to zero.

System and method for transmission of bursts of digital information

A system and method for frequency acquisition by a mobile receiver 14 in a cellular communication system. Data for part of a frame 10 is sampled. Synchronization pattern 36 is rotated by a pattern rotator 37 to simulate fixed frequency offsets. The known sync pattern 36 is correlated with the sampled data by correlator 30 for a number of phase advances corresponding to the simulated fixed frequency offsets. The peak outputs 54 and 58 of the correlator 30 for the number of fixed frequency offsets is interpolated by parabolic interpolator 46 to adjust the receivers voltage controlled crystal oscillator 49 to reduce the offset.

System and method for minimizing frequency offsets between digital

In a wireless digital telephone system, a circuit for determining in a subscriber unit whether a particular RF channel is of the type designated by the base station to be either a control channel or a voice channel and for determining whether the channel is in the transmit or receive mode; the circuit utilizing the duration of an AM hole to determine the type of the channel and utilizing a unique word for determining the mode.

A digital wireless subscriber telephone unit for wireless communication with a base station. An IF is used within the subscriber unit and base station which is combined with a carrier signal generated by a synthesizer for RF transmission between stations. In intervals between actuation of the system, a training mode is used wherein a known training signal is compared with a known values to produce correction coefficients to compensate for undesirable variations in timing and/or frequency, these constants being stored for use in correcting actual received signals. During demodulation, the modulated digital signals are fed to the modem processor in the form of time multiplexed I and Q samples and are demultiplexed. The demultiplexed I and Q samples are fed to an equalizer and frequency correction circuit for minimization of errors for production of a frequency correction signal based upon the correction coefficients which is used to correct any errors in the timing and frequency of the system.

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San Diego, CA, United States of America

David N Critchlow