Centralized channel selection in a distributed RF antenna system

• US 5,930,682 A
• Filed: 05/28/1997
• Issued: 07/27/1999
• Est. Priority Date: 04/19/1996
• Status: Expired due to Term

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: LGC Wireless Incorporated (TE Connectivity Limited)
• Inventors: Yeung, Simon P., Schwartz, Adam L., Cutrer, David M., Georges, John B.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Bhattacharya, Sam
• Application Number:
  US08/864,298
• Time in Patent Office: 790 Days
• Field of Search: 455/14, 455/20, 455/22, 455/63, 455/66, 455/208, 455/209, 455/316, 455/317, 455/318, 455/319, 455/11.1, 455/12.1
• US Class Current: 455/14
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F
• CPC Class Codes: H03D 7/163 the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H03L 7/07 using several loops, e.g. for redundant clock signal generation
• CPC Class Codes: H03L 7/23 with pulse counters or frequency dividers
• 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 1/26 for superheterodyne receivers multiple frequency-changing H03D7/16
• CPC Class Codes: H04B 3/00 Line transmission systems combined with near-field transmission systems H04B5/00
• CPC Class Codes: H04B 7/2609 Arrangements for range control, e.g. by using remote antennas
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

Individual channels are centrally and tunably selected for emission in a distributed wireless communications system. A high-frequency signal received at a central antenna is down-converted such that a selected channel corresponds to a predetermined frequency range. Non-selected channels are filtered out. The selected channel is transmitted to remote locations over commonly available transmission lines, up-converted, and re-emitted. The transmitted channel is chosen by tuning the frequency of the local oscillator used for down-conversion. A high-stability global tuning signal is used to tune and stabilize the local oscillators used for up-conversion. The global tuning signal is generated by frequency-dividing the down-conversion local oscillator signal by a fixed number, while the up-conversion local oscillator signals are generated by frequency-multiplying the global tuning signal by the same fixed number. Phase-locked loops are used for frequency multiplication and stabilization. Applications include cellular communications, cordless telephony, local RF communications, interactive multimedia video, and high bit-rate local communications.

Claims

1. A distributed wireless communications system with centralized tunable channel selection, comprising:

a) a central receiving means for receiving a central high-frequency signal comprising a plurality of channels {C j!}, j=1 . . . J;

b) a central tunable channel selection means for tunably selecting a channel C k! for emission, comprising

a central mixing means in communication with said central receiving means, for generating an intermediate signal from said central high-frequency signal and a central reference signal, said intermediate signal comprising a channel C'"'"' k! corresponding to said channel C k!,

a central reference means in communication with said central mixing means, for controlling a frequency of said central reference signal such that said channel C'"'"' k! is suitable for transmission through a filtering means, and

a global tuning means in communication with said central reference means, for generating a global tuning signal;

c) a plurality of remote mixing means in communication with said central mixing means over said filtering means, for generating a corresponding plurality of remote high-frequency signals, wherein a remote mixing means generates a remote high-frequency signal from said intermediate signal and a remote reference signal, said remote high-frequency signal comprising said channel C k!; and

d) a plurality of remote emission means, wherein a remote emission means is in communication with said remote mixing means and emits said remote high-frequency signal;

wherein said global tuning signal controls a frequency of said remote reference signal, and thereby controls a frequency of said remote high-frequency signal.

2. The system of claim 1 wherein said remote mixing means is in communication with said central mixing means over a transmission means suitable for transmitting said intermediate signal, and unsuitable for transmitting said central high-frequency signal.

3. The system of claim 1 wherein said global tuning signal has a stable frequency relationship with said central reference signal.

4. The system of claim 1 further comprising a remote reference means in communication with said global tuning means, for controlling said frequency of said remote reference signal using said global tuning signal.

5. The system of claim 4 wherein said remote reference means is adapted to generate said remote reference signal by performing a fixed operation on said global tuning signal.

6. The system of claim 4 wherein said remote frequency control means is adapted to frequency-stabilize said remote reference signal using said global tuning signal.

7. The system of claim 4 wherein said remote frequency control means comprises a phase-locked loop for phase-locking said remote reference signal to said global tuning signal.

8. The system of claim 4 wherein said remote reference means comprises a frequency multiplication means for generating said remote reference signal by frequency-multiplying said global tuning signal.

9. The system of claim 8 wherein said frequency multiplication means is adapted to multiply said global tuning signal by a fixed number.

10. The system of claim 8 wherein said frequency multiplication means comprises a phase-locked loop.

11. The system of claim 8 wherein said global tuning means comprises a frequency division means for generating said global tuning signal by frequency-dividing said central reference signal.

12. The system of claim 1 wherein said central channel selection means comprises a high-stability oscillator for generating a central high-stability signal, wherein said global tuning signal has a stable frequency relationship with said central high-stability signal.

13. The system of claim 12 wherein said high-stability oscillator comprises a temperature-stabilized crystal oscillator.

14. The system of claim 1 wherein said central reference means is adapted to generate said central reference signal by frequency-multiplying a high-stability signal by a ratio N/M, wherein

M and N are integers chosen such that an integer change in N corresponds to a change in a frequency of said central reference signal equal to an integer multiple of an interchannel spacing of said set {C j!}.

15. The system of claim 14 further comprising a remote reference means in communication with said global tuning means, wherein said remote reference means is adapted to generate said remote reference signal by frequency-multiplying said global tuning signal by said ratio N/M.

16. The system of claim 1 wherein said remote signal consists essentially of said channel C k!.

17. The system of claim 1 wherein said remote emission means comprises a repeater antenna for wireless communications.

18. The system of claim 17 wherein said central receiving means comprises a receiver antenna for wireless communications.

19. The system of claim 1 further comprising a digitization means in communication with said filtering means, for digitizing said intermediate signal.

20. The system of claim 1 wherein said channel C k! comprises a plurality of code-division-multiple-access carriers.

21. The system of claim 1 wherein said central high-frequency signal is within a frequency band selected from a group of bands for cellular communications, cordless telephony, personal communication services, local radio-frequency communications, satellite television, interactive multi-media video, and high bit-rate local area networks.

22. The system of claim 1 wherein said system is adapted for bi-directional communication.

23. The system of claim 1 wherein said central reference signal and said remote reference signal are frequency-matched within an interchannel spacing of said plurality of channels {C j!}.

24. The system of claim 1 wherein a frequency of said intermediate signal is substantially equal to a frequency difference between said central high-frequency signal and said central reference signal.

25. The system of claim 1 wherein said transmission means comprises a medium selected from a group of 10 base T cable, telephone wire, fiber-optic cable, unshielded cable, and power cable.

26. A distributed wireless communications system with centralized tunable channel selection, comprising:

a) a central receiver antenna for receiving a central high-frequency signal comprising a plurality of channels {C j!}, j=1 . . . J;

b) a central high-stability oscillator for generating a central high-stability signal;

c) a central phase-locked loop in communication with said central high-stability oscillator, for generating a central reference signal by frequency-multiplying said high-stability signal by a tunable number;

d) a central mixing means in communication with said central receiver antenna and said central phase-locked loop, for generating an intermediate signal by mixing said central high-frequency signal and said central reference signal;

e) a selection filter in communication with said central mixing means, for selecting a channel C'"'"' k! of said intermediate signal for transmission, said channel C'"'"' k! corresponding to a channel C k! of said central high-frequency signal, an identity of said channel C'"'"' k! being determined by said tunable number;

f) a frequency divider in communication with said central phase-locked loop, for generating a global tuning signal by frequency-dividing said central reference signal;

g) a plurality of remote phase-locked loops, wherein a remote phase-locked loop is in communication with said frequency divider, for generating a remote reference signal by frequency-multiplying said global tuning signal;

h) a plurality of remote mixing means, wherein a remote mixing means is in communication with said selection filter and said remote phase-locked loop, for generating a remote high-frequency signal by mixing said intermediate signal and said remote reference signal, said remote high-frequency signal comprising said channel C k!; and

i) a plurality of remote repeater antennas, wherein a remote repeater antenna is in communication with said remote mixing means, for emitting said remote high-frequency signal.

27. A distributed wireless communications system with centralized tunable channel selection, comprising:

a) a central receiving means for receiving a central high-frequency signal comprising a plurality of channels {C j!}, j=1 . . . J;

b) a tunable central channel selection means in communication with said central receiving means, wherein said central channel selection means comprises

a central mixing means for generating an intermediate signal from said central high-frequency signal and a tunable central reference signal, said intermediate signal defining a channel C k! selected for emission, and

a means for generating a global tuning signal;

c) a plurality of remote reference means in communication with said central channel selection means, a remote reference means generating a remote reference signal by performing a fixed operation on said global tuning signal, said global tuning signal determining a frequency of said remote reference signal;

d) a plurality of remote mixing means in communication with said central mixing means, a remote mixing means being in communication with said remote reference means, said remote mixing means generating a remote high-frequency signal from said intermediate signal and said remote reference signal, said remote high-frequency signal comprising said channel C k!; and

e) a plurality of remote emission means, a remote emission means being in communication with said remote mixing means, for emitting said remote high-frequency signal.