Digital radio frequency transceiver system and method

• US 9,548,878 B2
• Filed: 10/21/2014
• Issued: 01/17/2017
• Est. Priority Date: 03/12/2008
• Status: Active Grant

• Current Assignee: Hypres, Inc.
• Original Assignee: Hypres, Inc.
• Inventors: Gupta, Deepnarayan, Mukhanov, Oleg
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US14/519,197
• Publication Number:
  US 20150125155A1
• Time in Patent Office: 819 Days
• Field of Search: 398202-214
• US Class Current: 1/1
• CPC Class Codes: H04B 10/2575 Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
• CPC Class Codes: H04B 10/25752 Optical arrangements for wireless networks
• CPC Class Codes: H04B 10/40 Transceivers
• CPC Class Codes: H04B 10/5561 Digital phase modulation
• CPC Class Codes: H04B 10/697 Arrangements for reducing noise and distortion
• CPC Class Codes: H04L 27/2096 Arrangements for directly or externally modulating an optical carrier optical modulation H04B10/503

Abstract

A transceiver architecture for wireless base stations wherein a broadband radio frequency signal is carried between at least one tower-mounted unit and a ground-based unit via optical fibers, or other non-distortive media, in either digital or analog format. Each tower-mounted unit (for both reception and transmission) has an antenna, analog amplifier and an electro-optical converter. The ground unit has ultrafast data converters and digital frequency translators, as well as signal linearizers, to compensate for nonlinear distortion in the amplifiers and optical links in both directions. In one embodiment of the invention, at least one of the digital data converters, frequency translators, and linearizers includes superconducting elements mounted on a cryocooler.

Claims

1. A communication system, comprising:

an analog device configured to produce an electrical analog domain signal within a corresponding frequency band representing a superposition of;

a received signal containing information, and at least one intermodulation distortion product of components of the received signal within the frequency band, the at least one intermodulation distortion product being interfering with demodulation of the information contained in the received signal, and non-filterable from the received signal by frequency-domain filtering without loss of the information contained in the received signal;

a digitizer configured to quantize the electrical analog domain signal;

at least one memory configured to store information corresponding to parameters of a model of intermodulation distortion properties of the analog device; and

a digital signal processor configured to receive the quantized electrical analog domain signal, read the stored information from the memory, process the quantized electrical analog domain signal to attenuate a digital representation of the at least one intermodulation distortion product with respect to a digital representation of the received signal, selectively dependent on the model of intermodulation distortion properties of the analog device, the representation of the at least one intermodulation distortion product being attenuated substantially without loss of the information contained in the received signal.

2. The communication system according to claim 1, wherein the frequency band comprises a frequency of 698 MHz or greater, and the digitizer is configured to quantize at a rate of at least 1.4 gigasamples per second.

3. The communication system according to claim 1, wherein the frequency band has a range greater than about 20 MHz, and the digital signal processor is configured to attenuate the digital representation of the at least one intermodulation distortion product over the range of the frequency band.

4. The communication system according to claim 3, wherein the frequency band has a range of equal to or greater than about 60 MHz, and the digital signal processor is further configured to reduce an amplitude of the digital representation of the at least one intermodulation distortion product over the range of the frequency band by at least 3 dB, and to improve an effective spur-free dynamic range of the digitized electrical analog domain representation.

5. The communication system according to claim 1, wherein the digital processor comprises a plurality of lookup tables, and is configured to deconvolve a non-linear distortion of the analog device.

6. The communication system according to claim 1, wherein the digitizer comprises a Josephson junction configured to produce digital pulses corresponding to the electrical analog domain signal at a rate of at least 10 GHz.

7. The communication system according to claim 1, further comprising a digital channelizer configured to segregate a broadband radio frequency signal represented in the received radio frequency signal into a plurality of different independent communication channels.

8. A method of receiving a signal containing information, comprising:

providing an analog device configured to produce an electrical analog domain signal within a corresponding frequency band representing a superposition of a received signal and at least one intermodulation distortion product of the components of the received signal within the frequency band;

producing the electrical analog domain signal representing the superposition of the received signal and the at least one intermodulation distortion product of the components of the received signal within the frequency band, the at least one intermodulation distortion product being interfering with recovery of the information contained in the received signal, and non-filterable from the received signal by frequency-domain filtering without loss of the information contained in the received signal;

quantizing the electrical analog domain signal with a digitizer to produce a digitized signal;

storing information corresponding to parameters of a model of intermodulation distortion properties of the analog device in a memory; and

attenuating a digital representation of the at least one intermodulation distortion product in the digitized signal, with respect to the digital representation of the received signal in the digitized signal with a digital signal processor, selectively dependent on the model of intermodulation distortion properties of the analog device stored in the memory, substantially without loss of the information contained in the received signal.

9. A communication system, comprising:

an input configured to receive a communicated radio frequency signal in a frequency band comprising communicated information;

a nonlinear analog device within an analog signal processing chain of the communication system, configured to generate an analog signal comprising at least one intermodulation distortion product within the frequency band superposed in the frequency domain on a representation of the communicated radio frequency signal in the frequency band comprising the communicated information, the at least one intermodulation distortion product within the frequency band being an interfering signal with respect to demodulation of the communicated information and being non-filterable in a frequency domain from the representation of the communicated radio frequency signal in the frequency band comprising communicated information without loss of the communicated information;

an analog to digital converter configured to quantize the analog signal to produce a quantized signal;

at least one automated digital signal processor configured to;

receive the quantized signal;

maintain a model of the at least one intermodulation distortion product within the frequency band;

process the received quantized signal, in dependence on the model, to selectively increase a ratio of an amplitude of the representation of the communicated radio frequency signal in the frequency band comprising communicated information to an amplitude of the at least one intermodulation distortion product, without loss of the communicated information; and

a demodulator, configured to extract the communicated information from the processed quantized signal.

10. The communication system according to claim 9, wherein the frequency band comprises a frequency of 698 MHz or greater, and the analog to digital converter is configured to quantize at a rate of at least 1.4 gigasamples per second.

11. The communication system according to claim 9, wherein the frequency band has a bandwidth equal to or greater than about 20 MHz.

12. The communication system according to claim 9, wherein the frequency band has a bandwidth equal to or greater than about 60 MHz.

13. The communication system according to claim 12, wherein the at least one automated digital signal processor is further configured to increase the signal to noise ratio by at least 3 dB.

14. The communication system according to claim 12, wherein the at least one automated digital signal processor is further configured to increase the spur free dynamic range of the quantized signal.

15. The communication system according to claim 9, wherein the at least one automated digital processor comprises a plurality of lookup tables, and is configured to deconvolve a non-linear distortion of the nonlinear analog device.

16. The communication system according to claim 9, wherein the analog to digital converter comprises at least one Josephson junction arranged to produce digital pulses corresponding to the output of the analog signal processing chain at a rate of at least 10 GHz.

17. The communication system according to claim 9, wherein the demodulator comprises a digital channelizer configured to segregate the processed quantized signal into a plurality of different independent communication channels.

18. A communication method, comprising:

receiving a communicated radio frequency signal in a frequency band comprising communicated information;

distorting the communicated radio frequency signal with a nonlinear analog device within an analog signal processing chain of the communication system, generating at least one intermodulation distortion product within the frequency band superposed on a representation of the communicated radio frequency signal, the at least one intermodulation distortion product being associated with errors in demodulated communicated information, and having frequency components which are not frequency domain filterable from the representation of the communicated radio frequency signal;

quantizing an output of the analog signal processing chain comprising the communicated radio frequency signal and the at least one intermodulation distortion product with an analog to digital converter;

digitally modelling the at least one intermodulation distortion product within the frequency band as a function of the communicated radio frequency signal;

digitally processing the quantized output of the analog signal processing chain, in dependence on the model of the at least one intermodulation distortion product within the frequency band, to selectively deconvolve the distorting to reduce interference of the at least one intermodulation distortion product with a demodulation of the communicated information substantially without loss of the communicated information; and

demodulating the communicated information from the processed quantized output of the analog signal processing chain with a reduced bit error rate with respect to demodulating the communicated information from the quantized output of the analog signal processing chain.

19. The method according to claim 18, wherein the frequency band has a bandwidth equal to or greater than about 20 MHz, wherein said processing decreases a distortion of the quantized output of the analog signal processing chain by at least 3 dB.

20. The method according to claim 18, wherein the communicated radio frequency signal in a frequency band comprises an orthogonal frequency domain multiplexed signal.