Cellular communication system with virtual antennas

• US 6,760,593 B1
• Filed: 03/13/2000
• Issued: 07/06/2004
• Est. Priority Date: 01/30/1997
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Driessen, Peter Frank
• Primary Examiner(s): GELIN, JEAN ALLAND
• Application Number:
  US09/524,243
• Time in Patent Office: 1,576 Days
• Field of Search: 455/500, 455/561, 455/562.1, 455/443, 455/444, 455/446, 455/447, 455/454, 455/422, 455/524, 455/61, 455/59, 455/522.1, 370/310, 370/328, 370/334, 370/345, 370/329, 370/330
• US Class Current: 455/500
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

In a cellular communication network, capacity in a cell is increased by placing antennas transmitting different signals on the same carrier frequency at separated signal transmission and virtual site locations in the cell, rather than at the center of the cell. A receiver includes multiple antennas using spatial diversity, such as beamforming and cancellation, to extract the desired signal.

Claims

1. A cellular communication system, comprising:

a plurality of signal transmission sites located at k−

v different positions in a cell with k≧

2;

at least v virtual sites wherein v≧

1;

a plurality of antennas located at the k−

v signal transmission sites, each antenna for transmitting one of m signals at the same carrier frequency in the cell with m≧

1, each of the signals being transmitted from at least one of the k−

v different positions, each of the signals representing a data signal devoid of a spreading signal; and

a receiving unit located in the cell at a location other than at the plurality of signal transmission sites and having;

at least two antennas for receiving the m signals transmitted at the same carrier frequency; and

a converter for converting the received signals into an output signal.

2. The system of claim 1, wherein at least one of the k−

v signal transmission sites are located around the perimeter of the cell.

3. The system of claim 1, wherein at least one of the k−

v different positions have at least two of the antennas located thereat.

4. The system of claim 3, wherein there are n antennas located at each of the k−

v different positions of the signal transmission sites with n=k.

5. The system of claim 4, wherein m=k and each of the n antennas at each of the k−

v different positions of signal transmission sites are operative to transmit a respective one of the m signals.

6. The system of claim 1, wherein at least one of the antennas receives the signal to be transmitted via a communication channel originating at one of the signal transmission sites for another of the antennas, and further comprising signal sources for providing each of the signals to one of the antennas transmitting the signals.

7. The system of claim 1, wherein at least one of the cells has microcells, each of the microcells having a plurality of microcell antennas and virtual antennas located at different positions of the microcell, each of the microcell antennas for transmitting one of at least two signals at the same carrier frequency, each of the at least two signals being transmitted from at least one of the different positions in the microcell.

8. The system of claim 1, wherein there are n antennas located at each of the k−

v different positions with n≧

2.

9. The system of claim 1, further comprising

a mobile unit having at least two antennas for receiving the m signals transmitted at the same carrier frequency and a converter for converting the received signals into an output signal.

10. The system of claim 9, wherein there are n antennas located at each of the k−

v different positions with n≧

2.

11. The system of claim 1, wherein the data signal represents a voice communication or a digital data communication.

20. The system of claim 1, further comprising a plurality of receiving antennas located at the signal transmission sites for receiving mobile signals transmitted from respective mobile antennas of a mobile unit at the same mobile carrier frequency, the plurality of receiving antennas operating simultaneously with the plurality of transmitting antennas located at the signal transmission sites.

21. The system of claim 20, wherein there are nr receiving antennas and nt transmitting antennas located at each of the k−

v different positions with nr≧

2 and nt≧

2.

12. A method for communicating m respectively different signals having the same carrier frequency in a cell of a cellular communication system, comprising the steps of:

providing the m respectively different signals having the same carrier frequency to a plurality of antennas located at k−

v different positions in the cell, wherein v is a number of virtual sites, each of the signals representing a respective data signal devoid of a spreading signal;

transmitting the signals respectively provided to the antennas; and

receiving the transmitted signals at a receiving unit located in the cell at a location other than at the k different positions and having;

at least two antennas for receiving the transmitted signals, and

a converter for converting the transmitted signals into an output signal.

13. The method of claim 12, wherein at least one of the antennas are located around the perimeter of the cell.

14. The method of claim 12, wherein at least one of the k−

v different positions have at least two of the antennas located thereat.

15. The method of claim 14, wherein there are n antennas located at each of the k−

v different positions of the signal transmission sites with n=k.

16. The method of claim 15, wherein m=k and each of the n antennas at each of the k−

v different positions of signal transmission sites are operative to transmit a respective one of the m signals.

17. The method of claim 12, further comprising signal sources for providing each of the signals to the antennas transmitting the signals in a serial sequence.

18. The method of claim 12, wherein at least one of the cells has microcells, each of the microcells having a plurality of microcell antennas and virtual antennas located at different positions of the microcell, each of the microcell antennas for transmitting one of at least two signals at the same carrier frequency, each of the at least two signals being transmitted from at least one of the different positions in the microcell.

19. The method of claim 12, wherein there are n antennas located at each of the k−

v different positions with n≧

2.

22. A method for cellular communication, comprising the steps of:

transmitting m respectively different signals having the same carrier frequency in a cell of a cellular communication system from a plurality of transmitting antennas located at k−

v different positions in the cell, wherein v is a number of virtual sites, each of the signals representing a data signal devoid of a spreading signal, at least one of the k−

v positions having at least two transmitting antennas,

receiving the m signals transmitted at the same carder frequency at a mobile unit having at least two antennas, and

converting the received signals into an output signal.

23. The method of claim 22, wherein there are n transmitting antennas located at each of the k−

v different positions with n≧

2.

24. A method for cellular communication, comprising the steps of

transmitting m respectively different signals having the same carrier frequency in a cell of a cellular communication system from at least two transmitting antennas located at a mobile unit in the cell, each of the signals representing a data signal devoid of a spreading signal,

receiving, at a plurality of receiving antennas located at the k−

v different positions in the cell, wherein v is a number of virtual sites, the transmitted signals, and

combining the transmitted signals to produce an output signal.

25. The system of claim 24, wherein there are nr receiving antennas and nt transmitting antennas located at each of the k−

v different positions with nr≧

2 and nt≧

2.

26. A cellular communication system, comprising:

sources of k different sub-signals representing portions of a single data stream and being devoid of a spreading signal;

at least v virtual sites;

a plurality of signal transmission sites located at k−

v different positions in a cell with k≧

2, and

at least one antenna located at each of the signal transmission sites, each antenna for transmitting one of the k different sub-signals.

27. A method for transmitting k respectively different sub-signals having the same carrier frequency in a cell of a cellular communication system, comprising the steps of:

providing the k different sub-signals representing portions of a single data stream and being devoid of a spreading signal to respective antennas located at a plurality of signal transmission sites at k−

v different positions in a cell with k≧

2, wherein v is a number of virtual sites, and

transmitting the different sub-signals from the antennas.

28. A method for cellular communication, comprising the steps of:

transmitting m respectively different signals having the same carrier frequency in a cell of a cellular communication system from a plurality of transmitting antennas located at k−

v different positions in the cell, wherein v is a number of virtual sites, each of the signals representing a data signal devoid of a spreading signal, at least one of the k−

v positions having at least two of the transmitting antennas,

receiving the m signals transmitted at the same carrier frequency at a receiving unit having at least two antennas, and

converting the received signals into an output signal.

29. A method for cellular communication, comprising the steps of

transmitting m respectively different signals having the same carrier frequency in a cell of a cellular communication system from a plurality of transmitting antennas located at a transmitting unit in the cell, each of the signals representing a data signal devoid of a spreading signal,

receiving, at a plurality of receiving antennas located at the k−

v different positions in the cell, the transmitted signals, wherein v is a number of virtual sites, and

combining the transmitted signals to produce an output signal.