Method and system of spread spectrum modulation

• US 7,197,288 B1
• Filed: 06/24/2002
• Issued: 03/27/2007
• Est. Priority Date: 06/24/2002
• Status: Active Grant

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Oh, Dae-Sik, Ngan, John Cheong-Wai, Fortuna, Frederick
• Primary Examiner(s): Beamer; Temica
• Assistant Examiner(s): CONTEE, JOY KIMBERLY
• Application Number:
  US10/178,426
• Time in Patent Office: 1,737 Days
• Field of Search: 455/522, 455/69, 455/456.1, 455/447, 455/515, 455/562, 455/561, 455/186.1, 455/42, 370/335, 370/342, 370/341, 370/334, 370/243, 370/345
• US Class Current: 455/186.1
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

A method and system of communicating between a base station and a mobile station is disclosed. The base station may be the core of a cell site, which is defined by radio frequency radiation patterns. The cell site may be divided into a number of sectors, each defined respectively by radiation patterns. The mobile station, while within any of the sectors of the cell site, may communicate with the base station on a reverse link by encoding signals using a spreading sequence offset by a common time delay. On the forward link, each sector is assigned a respective time delay that is within the common time delay. While within a respective sector of the cell site, the mobile station may receive signals from the base station on the forward link that have been encoded with the spreading sequence offset by the sector'"'"'s respective time delay.

Claims

1. In a cellular base station of the type that radiates in a number of directions so as to provide a number of sectors each having a respective air interface through which a mobile station in a given sector communicates with the base station, a method comprising:

in all of the number of sectors, the base station receiving mobile station signals that have been encoded with a common spreading sequence;

assigning to each sector of the number of sectors a respective time delay, such that any adjacent sectors of the number of sectors have different respective time delays than each other, the respective time delay being within a time window such that the mobile station would recognize a received signal encoded with the common spreading sequence offset by any of the respective time delays to be equivalently encoded signals; and

in each sector of the number of sectors, the base station (i) encoding a respective signal with the common spreading sequence offset by the sector'"'"'s respective time delay, so as to provide an encoded signal for the sector and (ii) sending the encoded signal into the sector'"'"'s respective air interface for receipt by a mobile station operating in the sector.

2. The method of claim 1, wherein receiving mobile station signals that have been encoded with the common spreading sequence comprises receiving mobile station signals that have been encoded with a code division multiple access (CDMA) pseudo-noise (PN) sequence.

3. The method of claim 1, wherein receiving mobile station signals that have been encoded with the common spreading sequence comprises receiving mobile station signals that have been encoded with a pseudo-noise (PN) sequence offset by a common time delay.

4. The method of claim 3, wherein the common time delay is approximately 52 micro-seconds.

5. The method of claim 3, wherein assigning to each sector of the number of sectors the respective time delay comprises assigning to each sector a respective time slot of the common time delay of the PN sequence.

6. The method of claim 5, wherein encoding the respective signal with the common spreading sequence offset by the sector'"'"'s respective time delay comprises encoding the respective signal with the common spreading sequence offset by the sector'"'"'s respective time slot.

7. The method of claim 1, wherein encoding the respective signal with the common spreading sequence offset by the sector'"'"'s respective time delay comprises modulating the respective signal with the common spreading sequence offset by the sector'"'"'s respective time delay using spread spectrum modulation.

8. The method of claim 7, wherein modulating the respective signal comprises using a modulation technique selected from the group consisting of a direct sequence spreading technique and a frequency hopping spreading technique.

9. The method of claim 1, wherein encoding the respective signal with the common spreading sequence offset by the sector'"'"'s respective time delay comprises increasing a bandwidth of the respective signal.

10. The method of claim 1, wherein the common spreading sequence defines a sequence of chips, and wherein assigning to each sector of the number of sectors the respective time delay comprises assigning to each sector a respective subsequence of chips.

11. The method of claim 10, wherein assigning to each sector the respective subsequence of chips comprises assigning to each sector the respective subsequence of chips such that each respective subsequence of chips only differs by at most approximately 64 chips.

12. A cellular base station of the type that radiates in a number of directions so as to provide a number of sectors each having a respective air interface through which a mobile station in a given sector communicates with the base station,

wherein communications between the mobile station and the base station are encoded with a pseudo-noise (PN) sequence,

wherein reverse link communications between the mobile station while in any of the number of sectors and the cellular base station are encoded with the PN sequence offset by a common time delay, and

wherein forward link communications between the mobile station while in a respective sector of the number of sectors and the cellular base station are encoded with the PN sequence offset by a respective time delay that is within the common time delay such that forward link communications within any adjacent sectors of the number of sectors are encoded with the PN sequence offset by a different time delay than each other.

13. The cellular base station of claim 12, wherein the cellular base station produces an omni-sectored cell site.

14. The cellular base station of claim 12, wherein the common time delay corresponds to a code division multiple access (CDMA) PN-offset time window.

15. The cellular base station of claim 12, further comprising a receiver, a transmitter, and a processing unit.

16. The cellular base station of claim 15, wherein the processing unit is operable to execute machine language instructions comprising selecting the common time delay and selecting the respective time delays within the common time delay.

17. A system comprising:

means for providing radiation patterns that define a number of sectors of a cellular base station, each sector having a respective air interface;

means for differentiating signals transmitted from a mobile station to the cellular base station through any of the respective air interfaces by encoding the signals with a common spreading sequence offset by a common time delay; and

means for differentiating signals transmitted from the cellular base station to the mobile station through any of the respective air interfaces by encoding the signals with a respective portion of the common spreading sequence, wherein each respective air interface is assigned a different respective portion of the common spreading sequence.

18. The system of claim 17, wherein the means for providing radiation patterns comprise antenna-arrangements.

19. The system of claim 17, wherein the means for differentiating signals transmitted from the mobile station to the cellular base station comprise a processing unit operable to execute machine language instructions comprising encoding the signals transmitted from the mobile station to the cellular base station with the common spreading sequence offset by the common time delay.

20. The system of claim 17, wherein the means for differentiating signals transmitted from the cellular base station to the mobile station comprise a processing unit operable to execute machine language instructions comprising encoding the signals transmitted from the cellular base station to the mobile station with the common spreading sequence offset by a respective time slot of the common time delay.