Method of creating and utilizing diversity in a multiple carrier communication system

• US 9,277,470 B2
• Filed: 02/11/2013
• Issued: 03/01/2016
• Est. Priority Date: 08/08/2002
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Uppala, Sathyadev Venkata
• Primary Examiner(s): Mohebbi, Kouroush
• Application Number:
  US13/764,230
• Publication Number:
  US 20130150055A1
• Time in Patent Office: 1,114 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point
• CPC Class Codes: H04W 36/20 for optimising the interference level
• CPC Class Codes: H04W 52/0235 where the received signal is a power saving command
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/281 taking into account user or data type priority
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/286 during data packet transmission, e.g. high speed packet access [HSPA]
• CPC Class Codes: H04W 52/287 when the channel is in stand-by
• CPC Class Codes: H04W 52/288 taking into account the usage mode, e.g. hands-free, data transmission, telephone
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 68/02 Arrangements for increasing efficiency of notification or paging channel
• CPC Class Codes: H04W 68/025 Indirect paging
• CPC Class Codes: H04W 72/00 Local resource management
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In many cellular systems, reusing spectrum bandwidth, creates problems in boundary regions between the cells and sectors where the signal strength received from adjacent base stations or adjacent sector transmissions of a single base station may be nearly equivalent. The invention creates a new type of diversity, referred to as multiple carrier diversity by utilizing multiple carriers, assigning different power levels to each carrier frequency at each base station, and/or offsetting sector antennas. The cell and/or sector coverage areas can be set so as to minimize or eliminate overlap between cell and/or sector boundary regions of different carrier frequencies. Mobile nodes traveling throughout the system can exploit multiple carrier diversity by detecting carriers and selecting to use a non-boundary carrier based on other system criteria in order to improve performance. Boundary carriers may, but need not be, identified and excluded from consideration for use by a wireless terminal.

Claims

1. A method of a wireless terminal, comprising:

communicating with a base station using a first carrier provided within a first coverage area of the base station;

determining that the wireless terminal is in a boundary region for the first carrier that is non-overlapping with a boundary region for another carrier provided by the base station, the first carrier being subject to inter-cell interference or inter-sector interference greater than a threshold within the boundary region, and that the first carrier is a boundary carrier, the boundary carrier being a carrier provided at the boundary region that corresponds to a first overlapping area between at least two sectors within a cell of the base station or a second overlapping area between the cell of the base station and a neighboring cell of a neighbor base station, and the first overlapping area being associated with the inter-sector interference and the second overlapping area being associated with the inter-cell interference;

determining at least one candidate carrier provided by the base station that is a non-boundary carrier, the at least one candidate carrier excluding the first carrier and including a second carrier provided within a second coverage area of the base station; and

initiating a handoff from the first carrier to the second carrier.

2. The method of claim 1, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the communicating and the initiating occur within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

3. The method of claim 1, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the communicating and the initiating occur within the first coverage area and outside the second coverage area, and the handoff is an inter-cell handoff to the second carrier provided by the neighboring base station.

4. The method of claim 1, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the communicating and the initiating occur within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

5. The method of claim 1, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the communicating and the initiating occur within the second coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

6. The method of claim 1, wherein determining that the wireless terminal is in a boundary region for the first carrier comprises determining that a signal strength difference of the first carrier, measured by the wireless terminal, between the at least two sectors within the cell of the base station or between the cell of the base station and the neighboring cell of the neighbor base station is less than the predetermined value.

7. The method of claim 6, further comprising measuring a pilot tone strength difference between the at least two sectors within the cell of the base station or between the cell of the base station and the neighboring cell of the neighbor base station, wherein the signal strength difference is the measured pilot tone strength difference.

8. The method of claim 6, wherein the predetermined value is a signal strength difference of 20% or less.

9. The method of claim 6, wherein the predetermined value is a signal strength difference of 1 dB, 2 dB, 4 dB, 5 dB, or 6 dB.

10. The method of claim 1, wherein determining that the wireless terminal is in a boundary region for the first carrier comprises detecting, by the wireless terminal, a decrease in signal-to-noise ratio (SNR) of the first carrier to less than an upper threshold but still greater than a lower threshold.

11. The method of claim 10, wherein the upper threshold is 3 dB and the lower threshold is 0 dB.

12. A wireless terminal, comprising:

means for communicating with a base station using a first carrier provided within a first coverage area of the base station;

means for determining that the wireless terminal is in a boundary region for the first carrier that is non-overlapping with a boundary region for another carrier provided by the base station, the first carrier being subject to inter-cell interference or inter-sector interference greater than a threshold within the boundary region, and that the first carrier is a boundary carrier, the boundary carrier being a carrier provided at the boundary region that corresponds to a first overlapping area between at least two sectors within a cell of the base station or a second overlapping area between the cell of the base station and a neighboring cell of a neighbor base station, and the first overlapping area being associated with the inter-sector interference and the second overlapping area being associated with the inter-cell interference;

means for determining at least one candidate carrier provided by the base station that is a non-boundary carrier, the at least one candidate carrier excluding the first carrier and including a second carrier provided within a second coverage area of the base station; and

means for initiating a handoff from the first carrier to the second carrier.

13. The wireless terminal of claim 12, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the means for communicating communicates with the base station and the means for initiating initiates the handoff within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

14. The wireless terminal of claim 12, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the means for communicating communicates with the base station and the means for initiating initiates the handoff within the first coverage area and outside the second coverage area, and the handoff is an inter-cell handoff to the second carrier provided by the neighboring base station.

15. The wireless terminal of claim 12, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the means for communicating communicates with the base station and the means for initiating initiates the handoff within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

16. The wireless terminal of claim 12, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the means for communicating communicates with the base station and the means for initiating initiates the handoff within the second coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

17. A wireless terminal, comprising:

a processor configured to;

communicate with a base station using a first carrier provided within a first coverage area of the base station;

determine that the wireless terminal is in a boundary region for the first carrier that is non-overlapping with a boundary region for another carrier provided by the base station, the first carrier being subject to inter-cell interference or inter-sector interference greater than a threshold within the boundary region, and that the first carrier is a boundary carrier, the boundary carrier being a carrier provided at the boundary region that corresponds to a first overlapping area between at least two sectors within a cell of the base station or a second overlapping area between the cell of the base station and a neighboring cell of a neighbor base station, and the first overlapping area being associated with the inter-sector interference and the second overlapping area being associated with the inter-cell interference;

determine at least one candidate carrier provided by the base station that is a non-boundary carrier, the at least one candidate carrier excluding the first carrier and including a second carrier provided within a second coverage area of the base station; and

initiate a handoff from the first carrier to the second carrier; and

a memory operably connected to said processor.

18. The wireless terminal of claim 17, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the processor is configured to communicate with the base station and to initiate the handoff within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

19. The wireless terminal of claim 17, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the processor is configured to communicate with the base station and to initiate the handoff within the first coverage area and outside the second coverage area, and the handoff is an inter-cell handoff to the second carrier provided by the neighboring base station.

20. The wireless terminal of claim 17, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the processor is configured to communicate with the base station and to initiate the handoff within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

21. The wireless terminal of claim 17, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the processor is configured to communicate with the base station and to initiate the handoff within the second coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

22. A

a non-transitory computer-readable medium comprising code for:

communicating with a base station using a first carrier provided within a first coverage area of the base station;

determining that the wireless terminal is in a boundary region for the first carrier that is non-overlapping with a boundary region for another carrier provided by the base station, the first carrier being subject to inter-cell interference or inter-sector interference greater than a threshold within the boundary region, and that the first carrier is a boundary carrier, the boundary carrier being a carrier provided at the boundary region that corresponds to a first overlapping area between at least two sectors within a cell of the base station or a second overlapping area between the cell of the base station and a neighboring cell of a neighbor base station;

determining at least one candidate carrier provided by the base station that is a non-boundary carrier, the at least one candidate carrier excluding the first carrier and including a second carrier provided within a second coverage area; and

initiating a handoff from the first carrier to the second carrier.

23. The computer-readable medium of claim 22, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the code for communicating communicates with the base station and the code for initiating initiates the handoff within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

24. The computer-readable medium of claim 22, wherein the first carrier is subject to inter-cell interference greater than a threshold, the inter-cell interference within the boundary region is due to the first carrier being utilized by the neighboring cell of the neighboring base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the code for communicating communicates with the base station and the code for initiating initiates the handoff within the first coverage area and outside the second coverage area, and the handoff is an inter-cell handoff to the second carrier provided by the neighboring base station.

25. The computer-readable medium of claim 22, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power greater than the first power, the first coverage area is within the second coverage area, the code for communicating communicates with the base station and the code for initiating initiates the handoff within the first coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.

26. The computer-readable medium of claim 22, wherein the first carrier is subject to inter-sector interference greater than the threshold, the inter-sector interference within the boundary region is due to the first carrier being utilized by neighboring sectors of the base station, the first carrier is provided by the base station at a first power and the second carrier is provided by the base station at a second power less than the first power, the second coverage area is within the first coverage area, the code for communicating communicates with the base station and the code for initiating initiates the handoff within the second coverage area, and the handoff is an intra-cell handoff to the second carrier provided by the base station.