Low-power code division multiple access receiver
AssigneesSTMicroelectronics Asia Pacific Pte Ltd, National University of Singapore
InventorsKarthik Sathiavageeswaran, Christopher A. Aldridge, Mohamed Imtiyaz Iqbal
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Abstract
A low-power receiver architecture of use in direct sequence spread spectrum communications system receivers, such as in a code division multiple access system, is provided. The receiver employs analog correlation, wherein its analog-digital, converters are able to operate at the system symbol rate, and the requirement for finite impulse response filters is obviated. The low-power receiver architecture is also applicable as a front-end structure for multiple-mode receivers.
Claims25
A direct sequence spread spectrum receiver, comprising:
- amplifying and filtering circuitry to obtain a direct sequence spread spectrum received signal;
- a spreading code signal generator circuit to generate an analog spreading code signal;
- analog correlation detection circuitry to detect correlation between said received signal and said spreading code signal to produce an analog correlation signal;
- and
- analog-to-digital conversion circuitry to generate a digital data signal from said analog correlation signal,
- wherein the spreading code signal generator circuit includes a digital-to-analog converter (DAC) to convert a digital spreading code sequence into a corresponding analog signal, and includes a signal mixer arranged to mix an output from said DAC with a frequency signal to generate said analog spreading code signal.
A code division multiple access RAKE receiver, comprising:
- a plurality of receivers, each receiver including:
- amplifying and filtering circuitry to obtain a direct sequence spread spectrum received signal;
- a spreading code signal generator circuit to generate an analog spreading code signal;
- analog correlation detection circuitry to detect correlation between said received signal and said spreading code signal to produce an analog correlation signal;
- analog-to-digital conversion circuitry to generate a digital data signal from said analog correlation signal,
- wherein the spreading code signal generator circuit includes a digital-to-analog converter (DAC) to convert a digital spreading code sequence into a corresponding analog signal, and includes a signal mixer arranged to mix an output from said DAC with a frequency signal to generate said analog spreading code signal;
- and
- wherein outputs from the plurality of receivers are combined to generate a single digital data signal output.
A method for receiving and decoding a direct sequence spread spectrum signal in which a digital data signal having a baseband frequency is combined with a digital spreading code sequence and modulated for transmission at a carrier frequency, the method comprising:
- amplifying and filtering a received direct sequence spread spectrum signal;
- generating an analog spreading code signal corresponding to a transmission spreading code sequence;
- performing analog correlation detection between the received signal and the spreading code signal to obtain a correlation signal;
- and
- applying analog-to-digital conversion to the correlation signal to obtain a replica of the digital data signal, wherein the analog spreading code signal is modulated at said carrier frequency and the analog correlation detection is performed at the carrier frequency.
A method for receiving and decoding a direct sequence spread spectrum signal in which a digital data signal having a baseband frequency is combined with a digital spreading code sequence and modulated for transmission at a carrier frequency, the method comprising:
- amplifying and filtering a received direct sequence spread spectrum signal;
- generating an analog spreading code signal corresponding to a transmission spreading code sequence;
- performing analog correlation detection between the received signal and the spreading code signal to obtain a correlation signal;
- and
- applying analog-to-digital conversion to the correlation signal to obtain a replica of the digital data signal, wherein the analog spreading code signal is modulated at an intermediate frequency, the method including downmixing the received direct sequence spread spectrum signal to said intermediate frequency and performing the analog correlation detection at said intermediate frequency.
A method for receiving and decoding a direct sequence spread spectrum signal in which a digital data signal having a baseband frequency is combined with a digital spreading code sequence and modulated for transmission at a carrier frequency, the method comprising:
- amplifying and filtering a received direct sequence spread spectrum signal;
- generating an analog spreading code signal corresponding to a transmission spreading code sequence;
- performing analog correlation detection between the received signal and the spreading code signal to obtain a correlation signal;
- and
- applying analog-to-digital conversion to the correlation signal to obtain a replica of the digital data signal, wherein the analog spreading code signal includes orthogonal in-phase and quadrature components for correlation detection with corresponding components of the received signal in an analog domain, with resulting correlation signals combined before application of the analog-to-digital conversion.
A code division multiple access (CDMA) communication system, comprising:
- a receiver having:
- amplification and filter circuitry to obtain a direct sequence spread spectrum received signal;
- a spreading code signal generator circuit to generate an analog spreading code signal;
- analog correlation detection circuitry coupled to the amplification and filter circuitry and to the spreading code signal generator circuit to detect correlation between said received signal and said spreading code signal to produce an analog correlation signal;
- and
- analog-to-digital conversion circuitry coupled to the analog correlation detection circuitry to generate a digital data signal from said analog correlation signal;
- wherein the spreading code signal generator circuit includes a digital-to-analog converter (DAC) to convert a digital spreading code sequence into a corresponding analog signal, and includes a signal mixer arranged to mix an output from said DAC with a frequency signal to generate said analog spreading code signal.
Dependencies are inferred from the claim text.