Multi-frequency pilot beacon for CDMA systems

• US 6,556,551 B1
• Filed: 05/27/1999
• Issued: 04/29/2003
• Est. Priority Date: 05/27/1999
• Status: Expired due to Term

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: LGC Wireless Incorporated (TE Connectivity Limited)
• Inventors: Schwartz, Adam L.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Lee, John J
• Application Number:
  US09/321,312
• Time in Patent Office: 1,433 Days
• Field of Search: 370/320, 370/328, 370/331, 370/332, 370/333, 370/334, 370/335, 370/330, 370/342, 370/479, 455/436, 455/453, 455/450, 455/522, 455/442, 455/437
• US Class Current: 370/331
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/76 Pilot transmitters or receivers for control of transmission or for equalising
• CPC Class Codes: H04W 36/08 Reselecting an access point

Abstract

A multi-frequency pilot beacon adapted to a CDMA system using at least two different carrier frequencies, F1 and F2, for supplying PN sequences at these frequencies. The pilot beacon has a pseudorandom noise generator for supplying a pseudorandom noise sequence PN and a frequency conversion mechanism for converting the PN sequence to a first pilot beacon centered at the first CDMA carrier F1 and a second pilot beacon centered at the second CDMA carrier F2. The multi-frequency pilot beacon can be provided at a base station of a given cell to transmit the pilot beacons within that cell and the base station antenna can be used for transmitting the pilot beacons in this embodiment. Alternatively, multi-frequency pilot beacons can be provided wherever necessary within the CDMA system. The multi-frequency pilot beacon is useful in frequency hand-off operations and gathering information about cellular users in the CDMA system

Claims

1. A CDMA system with hand-off of a transceiver operating at a first CDMA carrier frequency F1 to either a second CDMA carrier frequency F2 or a third CDMA carrier frequency F3, said CDMA system comprising:

a) a multi-frequency pilot beacon comprising

i. a pseudorandom noise generator for supplying a plurality of pseudorandom noise sequences, each of said plurality of sequences PN_X having a unique offset associated with it;

ii. a frequency conversion means for converting a first number of said plurality of pseudorandom noise sequences to a first pilot beacon centered at said first CDMA carrier frequency F1, a second number of said plurality of pseudorandom noise sequences to a second pilot beacon centered at said second CDMA carrier frequency F2, and a third number of said plurality of pseudorandom noise sequences to a third pilot beacon centered at a third CDMA carrier frequency F3;

iii. a transmitting means for transmitting said first, second and third pilot beacons to said transceiver;

a) a CDMA system controller which issues a hand-off decision from said first CDMA carrier frequency F1 to either said second CDMA carrier frequency F2 or said third CDMA carrier frequency F3 based on said pseudorandom noise offsets detected and reported by said transceiver.

2. The CDMA system of claim 1, wherein said first number of said plurality of pseudorandom noise sequences is different from said second number and said third number of said plurality of pseudorandom noise sequences.

3. The CDMA system of claim 1, wherein said first number of said plurality of pseudorandom noise sequences comprises a sequence with a first offset, and said second number of said plurality of pseudorandom noise sequences comprises a sequence with a second offset, and said third number of said plurality of pseudorandom noise sequences comprises a sequence with a third offset wherein said first second and third offsets are different.

4. The CDMA system of claim 1, wherein said first, second and third pilot beacons are transmitted within one cell.

5. The CDMA system of claim 4, wherein said first, second and third pilot beacons are transmitted by a base station.

6. The CDMA system of claim 4, wherein said transmitting means comprises a beacon unit and said first, second and third pilot beacons are transmitted from said beacon unit.

7. The CDMA system of claim 1, wherein said pseudorandom noise sequence PN_X is a digital pseudorandom noise sequence and said multi-frequency pilot beacon further comprises a digital-to-analog converter for converting said digital pseudorandom noise sequence to an analog pseudorandom noise sequence.

8. The CDMA system of claim 7, wherein said pseudorandom noise sequence PN_X is converted to an analog signal at an intermediate frequency.

9. The CDMA system of claim 1, wherein said CDMA controller comprises a means for issuing a hand-off order to said transceiver.

10. A method for handing-off a transceiver operating at a first CDMA carrier frequency F1 to either a second CDMA carrier frequency F2 or a third CDMA carrier frequency F3, said method comprising the following steps:

a) generating a plurality of pseudorandom noise sequences, each of said plurality of sequences PN_X having a unique offset associated with it;

b) converting a first number of said pseudorandom noise sequences to a first pilot beacon centered at said first CDMA carrier frequency F1, a second number of said pseudorandom noise sequences to a second pilot beacon centered at said second CDMA carrier frequency F2, and a third number of said pseudorandom noise sequences to a third pilot beacon centered at said third CDMA carrier frequency; and

c) transmitting said first, second and third pilot beacons to said transceiver; and

d) using said first, second and third pilot beacons for determining a hand-off decision between said first CDMA carrier frequency F1 and either said second CDMA carrier frequency F2 or said third CDMA carrier frequency F3 based on said pseudorandom noise offsets detected and reported by said transceiver.

11. The method of claim 10, wherein said first number of said plurality of pseudorandom noise sequences is different from said second number and said third number of said plurality of pseudorandom noise sequences.

12. The method of claim 10, wherein said first number of said plurality of pseudorandom noise sequences comprises a sequence with a first offset, and said second number of said plurality of pseudorandom noise sequences comprises a sequence with a second offset, and said third number of said plurality of pseudorandom noise sequences comprises a sequence with a third offset, wherein said first, second and third offsets are different.

13. The method of claim 10, further comprising the step of issuing a hand-off order to said transceiver.

14. The method of claim 13, wherein said hand-off order is determined from a first traffic volume at said first CDMA carrier frequency F1, a second traffic volume at said second CDMA carrier frequency F2, and a third traffic volume at said third CDMA carrier frequency F3.

15. The method of claim 13, wherein said hand-off order is determined from a location of said transceiver.

16. The method of claim 10, wherein said first CDMA carrier frequency F1, said second CDMA carrier frequency F2, and said third CDMA carrier frequency belong to a first base station.

17. The method of claim 10, wherein said first CDMA carrier frequency F1 belongs to a first base station and said second CDMA carrier frequency F2 belongs to a second base station.

18. The method of claim 10, wherein said first, second and third pilot beacons are transmitted independently.

19. The method of claim 10, wherein said first, second and third pilot beacons are transmitted jointly.

20. A CDMA system with hand-off of a transceiver operating at a first CDMA carrier frequency F1 to either a second CDMA carrier frequency F2 or a third CDMA carrier frequency F3, said CDMA system comprising:

a) a multi-frequency pilot beacon comprising;

i.) a pseudorandom noise generator for supplying a plurality of pseudorandom noise sequences, each of said plurality of sequences having a unique offset associated with it;

ii.) a transmitting means for transmitting said plurality of noise sequences to said transceiver;

a) a CDMA system controller which issues a hand-off decision from said first CDMA carrier frequency F1 to either said second CDMA carrier frequency F2 or said third CDMA carrier frequency F3 based on said pseudorandom noise offsets detected and reported by said transceiver.

21. A method for handing-off a transceiver operating at a first CDMA carrier frequency F1 to either a second CDMA carrier frequency F2 or a third CDMA carrier frequency F3, said method comprising the following steps:

a) generating a plurality of pseudorandom noise sequences, each of said plurality of sequences having a unique offset associated with it;

b) transmitting said plurality of pseudorandom noise sequences to said transceiver; and

c) using said plurality of pseudorandom noise sequences for issuing a hand-off decision between said first CDMA carrier frequency F1 and either said second CDMA carrier frequency F2 or said third CDMA carrier frequency F3 based on said pseudorandom noise offsets detected and reported by said transceiver.