Multi-band, multi-mode spread-spectrum communication system

• US 5,694,414 A
• Filed: 06/07/1995
• Issued: 12/02/1997
• Est. Priority Date: 05/13/1991
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Omnipoint Corp. (Deutsche Telekom AG)
• Inventors: Dixon, Robert C., Smith, Douglas G., Vanderpool, Jeffrey S.
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US08/482,292
• Time in Patent Office: 909 Days
• Field of Search: 375/295, 375/307, 375/275, 375/202, 375/344, 375/200, 455/188.1, 455/305, 455/306, 455/200.1
• US Class Current: 375/130
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/0057 using diplexing or multiplexing filters for selecting the desired band
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/7071 with dynamic control of receiver resources
• CPC Class Codes: H04B 7/2618 using hybrid code-time division multiple access [CDMA-TDMA]
• CPC Class Codes: H04B 7/2634 for channel frequency control
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A technique for spread-spectrum communication which uses more than one mode and more than one frequency band. Selectable modes include narrowband mode and spread-spectrum mode, or cellular mode and microcellular mode. Selectable frequency bands include both licensed and unlicensed frequency bands, particularly frequency bands including the 902-928 MHz, 1850-1990 MHz, and 2.4-2.4835 GHz frequency bands. Spread-spectrum communication channels are 10 MHz or less in width. The frequency band onto which spread-spectrum signals are encoded may be changed upon a change in environment or other control trigger, such as establishment or de-establishment of communication with a private access network. A multi-band transmitter comprises a single frequency synthesizer and a frequency source (e.g., a local oscillator), coupled to a selectable band pass filter. A multi-band receiver capable of monitoring one or more frequency bands comprises bank of bandpass filters and a demodulator comprising a single frequency synthesizer and a frequency source.

Claims

1. An apparatus for multi-band spread spectrum communication, comprising:

a dual-band frequency source comprising;

a frequency synthesizer outputting synthesized signals having a a first synthesized frequency range,

a fixed frequency source outputting a signal comprising a second frequency, and

a multiplier having as a first input the output of said frequency synthesizer and having as a second input the output of said fixed frequency source, said multiplier having a first output frequency range and a second frequency range; and

a binary encoder coupled to said dual-band frequency source.

2. The apparatus of claim 1 wherein

said first output frequency range is defined by summation of said first synthesized frequency range and said second frequency;

and

said second output frequency range is defined by taking the difference between said first synthesized frequency range and said second frequency.

3. The apparatus of claim 2 wherein the second frequency is about 2200 megahertz.

4. The apparatus of claim 2 wherein the first synthesized frequency range is between about 300 and 440 megahertz.

5. The apparatus of claim 1 wherein said binary encoder comprises a spread-spectrum encoder.

6. The apparatus of claim 1 wherein said first output frequency range spans from 2400 megahertz to 2483.5 megahertz.

7. The apparatus of claim 1 wherein said second output frequency range spans from 1850 megahertz to 1990 megahertz.

8. The apparatus of claim 1 wherein said frequency synthesizer comprises:

a reference frequency signal source;

a programmable divide-by-N counter;

a multiplier having inputs coupled to said programmable divide-by-N counter and said reference frequency signal source; and

a voltage-controlled oscillator having an input coupled to said multiplier, said voltage-controlled oscillator having an output coupled to said programmable divide-by-N counter.

9. The apparatus of claim 1 wherein a signal having a frequency in both of said first and second output frequency ranges are transmitted at once.

10. The apparatus of claim 1 further comprising a multi-band spread spectrum receiver.

11. The apparatus of claim 10 wherein said multi-band spread spectrum receiver monitors a frequency in both of said first and second output frequency ranges at once.

12. An apparatus for multi-band spread-spectrum communication comprising:

a spread spectrum signal generator, comprising;

a spread spectrum encoder having as an input information to be encoded and having as an output a spread spectrum signal, said spread spectrum signal being modulated by a first signal having a first frequency, and said spread spectrum signal generator outputting a modulated spread spectrum signal comprising the first frequency;

a frequency synthesizer outputting a synthesized signal comprising a second frequency;

a multiplier having a first input coupled to said frequency synthesizer and a second input coupled to said spread spectrum signal generator, said multiplier generating a bimodal signal by multiplying said modulated spread spectrum signal and said synthesized signal;

a filter coupled to said bimodal signal, said filter having at least a first output frequency range and a second output frequency range;

said first output frequency range is defined by summation of said first frequency and said second frequency; and

said second output frequency range is defined by taking the difference between said first frequency and said second frequency.

13. The apparatus of claim 12 wherein the information is encoded by the spread spectrum signal generator by modulating the information with a PN code.

14. The apparatus of claim 12 wherein the information is encoded by the spread spectrum signal generator using an M-ary spread spectrum technique.

15. The apparatus of claim 12 wherein said filter comprises:

a first band pass filter comprising a center filtering frequency defined by summation of said first frequency and said second frequency; and

a second band pass filter comprising a center filtering frequency defined by taking the difference between said first frequency and said second frequency.

16. The apparatus of claim 15 wherein said filter further comprises a wideband amplifier coupled to a band select signal.

17. The apparatus of claim 12 wherein said filter comprises:

a first narrowband power amplifier which operates at a frequency defined by summation of said first frequency and said second frequency, said first narrowband power amplifier outputting a first amplified signal; and

a second narrowband power amplifier which operates at a frequency defined by taking the difference between said first frequency and said second frequency, said second narrowband power amplifier outputting a second amplified signal.

18. The apparatus of claim 17 wherein said filter further comprises a multiplexer having an input coupled to said first amplified signal and an input coupled to said second amplified signal, said multiplexer outputting one of said first or second amplified signals in response to a control signal.

19. The apparatus of claim 17 wherein said filter further comprises at least one switch coupled to said first and second amplified signals, whereby one of said first or second amplified signals is selected in response to a control signal.

20. The apparatus of claim 12 wherein said spread spectrum signal generator further comprises:

a fixed signal source which outputs the first signal, said first signal being a carrier signal; and

a modulator having as inputs said output of said spread spectrum encoder and said output of said fixed signal source.

21. The apparatus of claim 12 wherein said frequency synthesizer comprises:

a reference frequency signal source;

a programmable divide-by-N counter;

a multiplier having inputs coupled to said programmable divide-by-N counter and said reference frequency signal source; and

a voltage-controlled oscillator having an input coupled to said multiplier, said voltage-controlled oscillator having an output coupled to said programmable divide-by-N counter.

22. The apparatus of claim 12 wherein said first output frequency range spans from 2400 megahertz to 2483.5 megahertz.

23. The apparatus of claim 12 wherein said second output frequency range spans from 1850 megahertz to 1990 megahertz.

24. The apparatus of claim 12 wherein a signal having a frequency in both of said first and second output frequency ranges are transmitted at once.

25. The apparatus of claim 12 wherein

said first output frequency range comprises a plurality of first frequency sub-bands;

said second output frequency range comprises a plurality of second frequency sub-bands;

each one of said first frequency sub-bands is paired with a corresponding one of said second frequency sub-bands to define a plurality of frequency pairs; and

said second frequency is selected from a discrete group of frequencies corresponding to said plurality of frequency pairs.

26. The apparatus of claim 12 further comprising a multi-band spread spectrum receiver.

27. The apparatus of claim 26 wherein the same frequency synthesizer is used for both transmitting and receiving.

28. A method of multi-band spread spectrum communication, comprising the steps of:

generating with a frequency synthesizer a first synthesized frequency range, said first synthesized frequency range being programmably selectable;

generating a signal comprising a fixed second frequency;

multiplying said first synthesized frequency range and said second frequency to generate multiplied signals having frequency components in each of two output frequency ranges, including a first output frequency range defined by summation of said first synthesized frequency range and said second frequency, and a second output frequency range defined by taking the difference between said first synthesized frequency range and said second frequency; and

encoding said multiplied signal.

29. The method of claim 28 wherein said encoding step comprises spread-spectrum encoding.

30. The method of claim 28 wherein multiplied signals having frequencies in both of said first output frequency range and second output frequency range are transmitted at once.

31. The method of claim 28 further comprising the step of receiving spread-spectrum signals.

33. The method of claim 28 wherein the second frequency is about 2200 megahertz.

34. The method of claim 28 wherein the first synthesized frequency range is between 300 and 440 megahertz.

32. The method of 31 wherein said receiving step monitors a frequency in both of said first and second output frequency ranges at once.

35. A method for multi-band spread-spectrum communication, comprising the steps of:

generating a modulated spread spectrum signal by encoding information in a spread spectrum encoder to generate a spread spectrum signal and multiplying said spread spectrum signal with a signal having a first frequency, said modulated spread spectrum signal comprising the first frequency;

generating with a frequency synthesizer a synthesized signal comprising a second frequency;

multiplying said modulated spread spectrum signal and said synthesized signal to generate a bimodal signal; and

filtering said bimodal signal to output a filtered signal having a first output frequency range and a second output frequency range, said first output frequency range is defined by summation of said first frequency and said second frequency, said second output frequency range is defined by taking the difference between said first frequency and said second frequency.

36. The method of claim 35 further comprising the step of selecting one of said first or second output frequency ranges.

37. The method of claim 35 wherein said filtering step comprises the steps of:

band pass filtering with a center filtering frequency defined by summation of said first frequency and said second frequency; and

band pass filtering with a center filtering frequency defined by taking the difference between said first frequency and said second frequency.

38. The method of claim 35 wherein said filtering step comprises the steps of:

amplifying said bimodal signal at a frequency defined by summation of said first frequency and said second frequency and outputting a first amplified signal; and

amplifying said bimodal signal at a frequency defined taking the difference between said first frequency and said second frequency and outputting a second amplified signal.

39. The method of claim 38 wherein said step of filtering further comprises the steps of multiplexing said first and second amplified signals and outputting one of said first or second amplified signals in response to a control signal.

40. The method of claim 38 wherein said step of filtering further comprises the step of switching said first and second signals and outputting one of said first or second amplified signals in response to a control signal.

41. The method of claim 35 wherein signals having frequencies in both of said first output frequency range and second output frequency range are transmitted at once.