Wideband base station architecture for digital cellular communications system

• US 5,768,268 A
• Filed: 07/19/1995
• Issued: 06/16/1998
• Est. Priority Date: 07/19/1995
• Status: Expired due to Fees

• Current Assignee: WJ Communications, Inc. (Qorvo, Inc.)
• Original Assignee: Watkins Johnson Co. (Qorvo, Inc.)
• Inventors: Harris, Timothy J., Anderson, Henry W., Kline, Paul A.
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Yao, Kwang Bin
• Application Number:
  US08/504,175
• Time in Patent Office: 1,063 Days
• Field of Search: 370/310, 370/328, 370/331, 370/336, 370/337, 370/345, 370/329, 370/330, 370/343, 379/59, 379/60, 455/33.1, 455/33.2, 455/76, 455/422, 455/39, 455/42, 455/507, 455/517, 375/295, 375/298, 375/302
• US Class Current: 370/330
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/0007 wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage
• CPC Class Codes: H04B 7/2646 for broadband transmission
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

An open-architecture digital cellular base station readily adapted to support communication over a variety of air interface standards is disclosed herein. The base station includes a wideband digital transceiver system having transmit and receive sections. Within the transmit section, an input line interface operates to couple a plurality of input information signals onto a time-division multiplexed (TDM) transmit bus. A plurality of digital transmitter modules are coupled to the TDM transmit bus, each of the digital transmitter modules generating a set of digital baseband signals in response to a corresponding set of the plurality of input information signals. The set of digital information signals are applied to a wideband summation network disposed to sequentially add the set of digital information signals into a wideband data stream. A wideband transmitter then generates a wideband transmission waveform using the wideband data stream. The receive section includes a wideband receiver for: (i) receiving an incident composite signal, and (ii) generating a digital representation of the incident composite signal in the form of a wideband digital data stream applied to a wideband data bus. A plurality of digital receiver modules are coupled to the wideband data bus. Each digital receiver module functions to recover a set of digital output signals from the wideband digital data stream, as well as to multiplex the set of digital signals onto a TDM receive bus. An output line interface serves to distribute the digital output signals among a plurality of output signal lines.

Claims

1. A wideband transmitter system for simultaneously transmitting a plurality of information signals provided by a corresponding plurality of input signal lines, comprising:

an input line interface configured to multiplex said plurality of information signals onto an input data bus;

a plurality of digital transmit modules coupled to said input data bus, each digital transmit module configured to process one or more of said information signals to produce one or more corresponding baseband signals, and each digital transmit module including;

(a) a modulator coupled to said iput data bus and configured to modulate a digital carrier siginal using one or more of said information signals in order to produce a modulated signal; and

(b) a digital frequency synthesizer coupled to said modulator and configured to translate said modulated signal to a predefined baseband frequency in order to produce said one or more baseband signals;

a wideband summation network coupled to said plurality of digital transmit modules and configured to add said one or more baseband signals from each of said digital transmit modules to produce a composite baseband signal onto a wideband data bus; and

a wideband transmitter coupled to said wideband data bus and configured to generate a transmission waveform in response to said composite baseband signal to simultaneously transmit said information signals.

2. The wideband transmitter system of claim 1 wherein each of said digital frequency synthesizers includes a digital oscillator selectively tuned to a different frequency.

3. The wideband transmitter system of claim 1 wherein said wideband summation network includes a plurality of digital adders, each of which is coupled to one of said digital frequency synthesizers and receives said one or more baseband signals produced thereby.

4. A wideband transmitter system for simultaneously transmitting a plurality of information signals provided by a corresponding plurality of input signal lines, comprising:

an input line interface configured to multiplex said plurality of information signals onto an input data bus;

a plurality of digital transmit modules coupled to said input data bus, each digital transmit module including a set of channel modules configured to produce a set of digital baseband signals of different frequencies corresponding to a set of said plurality of information signals, and each channel module including;

(a) a modulator coupled to said input data bus and configured to modulate a digital carrier signal using one or more of said information signals in order to produce a modulated signal; and

(b) a digital frequency synthesizer coupled to said modulator and configured to translate said modulated signal to a predefined basband frequency in order to produce one or more of said set of digital baseband signals;

a wideband summation network coupled to said digital transmit modules and configured to route a wideband data stream through said plurality of digital transmit modules and to add said set of digital baseband signals to said wideband data stream and onto a wideband data bus; and

a wideband transmitter coupled to said wideband data bus and configured to generate a wideband transmission waveform from said wideband data stream to simultaneously transmit said information signals.

5. The wideband transmitter system of claim 4 wherein said wideband transmitter includes:

a digital to analog converter for converting said wideband data stream to an analog data waveform, and

a wideband up-converter for modulating a radio frequency carrier signal using said analog data waveform.

6. A wideband receiver system for receiving an incident composite signal containing a plurality of information signals, comprising:

a wideband receiver configured to simultaneously receive said information signals as said incident composite signal and to generate a representation of said incident composite signal in the form of a data stream;

a baseband data bus coupled to said wideband receiver to which is applied said baseband data stream;

a plurality of digital receive modules coupled to said baseband data bus, each receive module configured to process said baseband data stream to produce one or more of said information signals, and each digital receive module including;

(a) a digital tuner coupled to said baseband data bus and configured to provide a digital representation of one or more of said information signals from said baseband data stream; and

(b) a demodulator coupled to said digital tuner and configured to demodulate said digital representation to provide one or more demodulated bit streams;

an output voice/data bus coupled to said plurality of digital receive modules onto which are applied said one or more demodulated bit streams to form a composite output bit stream; and

an output line interface coupled to said output voice/data bus and configured to distribute said plurality of demodulated bit streams within said composite output bit stream to a corresponding plurality of output signal lines.

7. The wideband receiver system of claim 6 wherein each of said digital receive modules further includes a decimator configured to decimate said digital representation of one or more of said information signals.

8. The wideband receiver system of claim 6 wherein each of said digital tuners includes a digital oscillator tuned to a different frequency.

9. The wideband receiver system of claim 6 wherein said wideband receiver includes:

a wideband down-converter for down-converting a frequency of said incident composite signal to a baseband signal; and

an analog to digital converter coupled to said wideband down-converter and configured to convert said baseband signal to said baseband data stream.

10. A wideband receiver system for receiving an incident composite signal containing a plurality of information signals, comprising:

a wideband receiver configured to simultaneously receive said information signals as said incident composite signal and to generate a digital representation of said incident composite signal in the form of a wideband digital data stream;

a wideband data bus coupled to said wideband receiver to which is applied said wideband digital data stream;

a plurality of digital receive modules coupled to said wideband data bus, each digital receive module including;

(a) a digital tuner coupled to said wideband data bus and configured each digital tuner disposed to provide a digital representation of one or more of said information signals from said wideband digital data stream; and

(b) a demodulator configured to generate a set of demodulated digital signals wherein each said set of demodulated digital signals is derived from a corresponding set of said plurality of information signals; and

an interface module for providing each said set of demodulated digital signals to a corresponding set of output signal lines.

11. The wideband receiver system of claim 10 wherein a first of said plurality of digital receive modules includes:

a first plurality of digital tuners coupled to said wideband data bus and

a first plurality of demodulators coupled to said first plurality of digital tuners.

12. A wideband digital transceiver system for transmitting a plurality of outbound information signals and receiving a plurality of inbound information signals, comprising:

an input line interface configured to multiplex said plurality of outbound information signals onto a TDM transmit bus;

a plurality of digital transmit modules coupled to said TDM transmit bus, each digital transmit module configured to process one or more of said outbound information signals to produce one or more corresponding outbound baseband signals, and each digital transmit module including;

(a) a modulator coupled to said TDM data bus and configured to modulate a digital carrier signal using one or more of said outbound information signal in order to produce an outbound modulated signal; and

(b) a digital frequency synthesizer coupled to said modulator and configured to translate said outbound modulated signal to a predefined baseband frequency in order to produce said one or more outbound baseband signals;

a wideband summation network coupled to said plurality of digital transmit modules and configured to add said one or more outbound baseband signals from each of said digital transmit modules into a composite baseband data stream;

a wideband transmitter coupled to said wideband summation network and configured to generate a wideband transmission waveform from said composite baseband data stream to simultaneously transmit said outbound information signals;

a wideband receiver configured to simultaneously receive said inbound information signals as an incident composite signal and to generate a digital representation of said incident composite signal in the form of a wideband digital data stream;

a wideband data bus coupeled to said wideband receiver to which is applied said wideband digital data stream;

a plurality of digital receive modules coupled to said wideband data bus, each receive module configured to process said wideband data stream to produce one or more of said inbound information signals and to multiplex said one or more inbound information signals onto a TDM receive bus, and each digital receive module including;

(a) a digital tuner couuned to said wideband data bus and configured to provide a digital representation of one or more of said information signals from said wideband digital data stream; and

(b) a demodulatr coupled to said digital tuner and configured to demodulate said digital representation to prvide one or more demodulated bit stream;

an output line interface coupled to said digital receive modules and configured to distribute said demodulated bit streams to a plurality of output signal lines.

13. The wideband digital transceiver system of claim 12 wherein each digital transmit module further includes a digital frequency synthesizer coupled to said modulator, each digital frequency synthesizer translating a frequency of said modulated signal to a predefined baseband frequency.

14. A method for combining a plurality of information signals provided by a corresponding plurality of input signal lines to transmit a wideband transmission waveform, said method comprising the steps of:

multiplexing said plurality of information signals onto an input data bus;

in a plurality of digital transmit modules coupled to said input data bus, simultaneously performing the steps of;

(a) modulating a digital carrier signal using one or more of said information signals in order to produce a modulated signal; and

(b) simultaneously translating said modulated signal to a predefined baseband frequency thereby producing one or more baseband signals;

combining said baseband signals to create a composite baseband data stream; and

generating said transmission waveform by using said composite baseband data stream to modulate an analog carrier signal.

15. A method of processing an incident composite signal containing a plurality of information signals, said method comprising the steps of:

simultaneously receiving said information signals as said incident composite signal and generating a digital representation of said incident composite signal in the form of a wideband digital data stream applied to a wideband data bus;

in a plurality of digital receive modules coupled to said wideband data bus, simultaneously peforming the steps of;

(a) recovering a digital representation of one or more of said information signals from said wideband digital data stream; and

(b) demodulating said digital representations of said information signals to provide one or more demodulated bit streams;

multiplexing said demodulated bit streams onto an output data bus in order to generate a composite output bit stream; and

distributing said demodulated bit streams within said composite output bit stream to a corresponding plurality of output signal lines.

16. A wideband transmitter for simultaneously communicating with a first mobile station and a second mobile station, comprising:

an outbound narrowband data bus adapted to receive a first outbound informnation signal and a second outbound information signal from a external structure;

a first digital transmit module coupled to said outbound narrowband data bus and configured to receive said first outbound information signal from said outbound narrowband data bus and to convert said first outbound information signal to a first outbound baseband signal, said first digital transmit module including;

(a) a first modulator coupled to said outbound narrowband data bus and configured to modulate a digital carrier signal using said first outbound information signal in order to produce a first outbound modulated signal; and

(b) a first digital frequency synthesiser coupled to said first modulator and configured to translate said first outbound modulated signal to predefined first baseband frequency in order to produce said first outbound baseband signal;

a second digital transmit module coupled to said outbound narrowband data bus and configured to receive said second outbound information signal from said outbound narrowband data bus and to convert said second outbound information signal to a second outbound baseband signal said second digital transmit module including;

(a) a second modulator coupled to said outbound narrowband data bus and configured to modulate a digital carrier signal using said second outbound information signal in order to produce a second outbound modulated signa1; and

(b) a second digital frequency synthesizer coupled to said second modulator and configured to translate said second outbound modulated signal to a predefined second baseband frequency in order to produce said second outbound baseband signal;

a combiner coupled to said first digital transmit module and said second digital transmit module and an outbound baseband data bus and configured to combine said first outbound baseband signal and said second outbound baseband signal as a composite outbound baseband signal and to provide said composite outbound baseband signal to said outbound baseband data bus; and

a wideband trmnsmitter coupled to said outbound baseband data bus and configured to modulate said comnposite outbound baseband signal and to transmit an outbound wideband signal to simultaneouly communicate with said first mobile station and said second mobile station.

17. A wideband receiver for simultaneously communicating with a first mobile station and a second mobile station, comprising:

a wideband receiver configured to receive and demodulate a composite inbound radio frequency signal to a composite inbound baseband signal onto an inbound baseband data bus;

a distributor coupled to said inbound baseband data bus and configured to distribute said composite inbound baseband signal to a plurality of digital receive modules;

a first digital receive module coupled to said distributor and configured to demodulate a portion of sad composite inbound baseband signal and to generate a first inbound narrowband signal said first digital receive module including;

(a) a digital tuner coupled to said inbound baseband data bus and configured to provide a digital representation of a first inbound information signal from said composite inbound baseband signal; and

(b) a demodulator coupled to said digital tuner and configured to demodulate said first inbound information signal to prvide said first inbound narrowband signal;

a second digital receive module coupled to said distributor and configured to demodulate a portion of said composite inbound baseband signal and to generate a second inbound narrowband signal said second digital receive module including;

(a) a digital tuner coupled to said inbound baseband data bus and configured to provide a digital representaton of a second inbound information signal from said composite inbound baseband signal; and

(b) a demodulator coupled to said digital tuner and configured to demodulate said second inbound information signal to provide said second inbound narrowband signal; and

an inbound narrowband data bus coupled to said first digital receive module and said second digital receive module and configured to communicate said first inbound narrowband signal and said second inbound narrowband signal to an external structure.

18. A wideband base station for simultaneously communicating with a first mobile station and a second mobile station, comprising:

a wideband transceiver configured to modulate a composite outbound baseband signal from an outbound baseband data bus and transmit a composite outbound radio frequency signal, and to receive and demodulate a composite inbound radio frequency signal to an inbound baseband signal onto an inbound baseband data bus;

an outbound narrowband data bus adapted to receive a first outbound information signal and a second outbound information signal from a external structure;

a first digital transmit module coupled to said outbound narrowband data bus and configured to receive said first outbound information signal from said outbound narrowband data bus and to convert said first outbound information signal to a first outbound baseband signal, said first digital transmit module including;

(a) a first modulator coupled to said outbound narrowband data bus and configured to modulate a digital carrier signal using said first outbound information signal in order to produce a first outbound modulated signal; and

(b) a first digital frequency synthesizer coupled to said first modulator and configured to translate said first outbound modulated signal to a predefined first baseband frequency in order to produce said first outbound baseband signal;

a second digital transmit module coupled to said outbound narrowband data bus and configured to receive said second outbound information signal from said outbound narrowband data bus and to convert said second outbound information signal to a second outbound baseband signal said second digital transmit module including;

(a) a second modulator coupled to said outbound narrowband data bus and configured to modulate a digital carrier signal using said second outbound information signal in order to produce a second outbound modulated signal; and

(b) a second digital frequency synthesizer coupled to said second modulator and configured to translate said second outbound modulated signal to a predefined second baseband frequency in order to produce said second outbound baseband signal;

a combiner coupled to said first digital transmit module and said second digital transmit module and said outbound baseband data bus and configured to combine said first outbound baseband signal and said second outbound baseband signal as said composite outbound baseband signal and to provide said composite outbound baseband signal to said outbound baseband data bus;

a distributor coupled to said inbound baseband data bus and configured to distribute said composite inbound baseband signal to a plurality of digital receive modules;

a first digital receive module coupled to said distributor and configured to demodulate a portion of said composite inbound baseband signal and to generate a first inbound narrowband signal, said first digital receive module including;

(a) a digital tuner coupled to said inbound baseband data bus and configured to provide a digital reprsentation of a first inbound information signal from said composite inbound baseband signal; and

(b) a demodulator coupled to said digital tuner and configured to demodulate said first inbound information signal to provide said first inbound narrowband signal;

a second digital receive module coupled to said distributor and configured to demodulate a portion of said composite inbound baseband signal and to generate a second inbound narrowband signal, said second digital receive module including;

(a) a digital tuner coupled to said inbound baseband data bus and configured to provide a digital representation of a second inbound information signal from said composite inbound baseband signal; and

(b) a demodulator coupled to said digital tuner and configured to demodulate said second inbound information signal to provide said second inbound narrowband signal; and

an inbound narrowband data bus coupled to said first digital receive module and said second digital receive module and configured to communicate said first inbound narrowband signal and said second inbound narrowband signal to an external structure.