Determining fractional frequency reuse power levels for downlink transmissions

• US 9,854,535 B2
• Filed: 07/28/2015
• Issued: 12/26/2017
• Est. Priority Date: 07/28/2015
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Madan, Ritesh K.
• Primary Examiner(s): TON, DANG T
• Application Number:
  US14/811,580
• Publication Number:
  US 20170034795A1
• Time in Patent Office: 882 Days
• Field of Search: 370329
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/245 taking into account received signal strength

Abstract

An example method is provided in one example embodiment and includes receiving at least one relative interference statistic from each of a plurality of cells, the at least one relative interference statistic associated with a relative interference of downlink transmission from the cell to a plurality of user equipment devices associated with the cell. The method further includes determining a power level for each of one or more resources within a fractional frequency reuse portion of a frequency spectrum based upon the at least one relative interference statistic received from each of the plurality of cells, and determining a power level for a reuse one portion of the frequency spectrum based upon the determined power level for each of the one or more resources within the fractional frequency reuse portion of the frequency spectrum.

Claims

1. A method, comprising:

receiving at least one relative interference statistic from each of a plurality of cells, the at least one relative interference statistic associated with a relative interference of downlink transmission from the cell to a plurality of user equipment devices associated with the cell;

determining a power level for each of one or more resources within a fractional frequency reuse portion of a frequency spectrum based upon the at least one relative interference statistic received from each of the plurality of cells; and

determining a power level for a reuse one portion of the frequency spectrum based upon the determined power level for each of the one or more resources within the fractional frequency reuse portion of the frequency spectrum.

2. The method of claim 1, wherein receiving the at least one relative interference statistic includes:

receiving a total number of user equipment devices connected to each of the plurality of cells;

receiving a total number of user equipment devices for each cell satisfying a first condition in which a neighboring cell Reference Signal Received Power (RSRP) value is at least equal a serving cell RSRP value plus a predetermined minimum relative interference value; and

receiving relative RSRP values for each cell satisfying the first condition.

3. The method of claim 2, wherein determining a power level for each of the one or more resources within the fractional frequency reuse portion includes:

ordering the user equipment devices in each of the plurality of cells decreasing order of their relative RSRP values;

computing signal-to-interference-plus-noise ratio (SINR) values for each of the user equipment devices based on the received relative RSRP values;

discarding the user equipment devices having an SINR value below a predetermined percentile value; and

determining a power level value of at least one resource within the fractional frequency reuse portion of a frequency spectrum based upon a predetermined selection criterion utilizing non-discarded user equipments within the predetermined percentile.

4. The method of claim 3, further comprising:

determining a power level value of a resource within a reuse one portion of the frequency spectrum based upon the determined power level of the at least one resource within the fractional frequency reuse portion.

5. The method of claim 2, further comprising:

ordering a set of user equipment device and interfering cell pairs in decreasing order of relative RSRP from an interfering cell with respect to a serving cell;

determining the pairs from the set with a serving cell RSRP less than a interfering cell RSRP plus a predetermined threshold value;

discarding user equipment devices from the set with a highest of a predetermined percentile of RSRP for neighboring cells; and

determining a power level value of at least one resource within the fractional frequency reuse portion of the frequency spectrum based upon a predetermined selection criterion utilizing non-discarded user equipments within the predetermined percentile.

6. The method of claim 1, wherein receiving the at least one relative interference statistic includes:

receiving relative Reference Signal Received Power (RSRP) values from each of the plurality of cells, wherein the relative RSRP values are ordered in descending order of a number of user equipment devices associated with the cell having a maximum value of relative interference such that the strongest interfering cell RSRP is equal to at least a serving cell RSRP plus a predetermined relative interference value;

ordering the cells in descending order of the number of neighbors of the cells within a predetermined percentile; and

determining relative power levels for each of one or more resources within a fractional frequency reuse portion of a frequency spectrum chosen such that when a particular cell transmits at a first power level and neighboring cells transmit at a second power level, a resulting interference is lowered to a predetermined threshold level below a serving cell power for cells within the predetermined percentile.

7. The method of claim 6, further comprising determining a power level value of the at least one resource within the fractional frequency reuse portion of the frequency spectrum based upon the relative power levels.

8. The method of claim 7, further comprising determining a power level value of a resource within a reuse one portion of the frequency spectrum based upon the determined power level of the at least one resource within the fractional frequency reuse portion.

9. One or more non-transitory tangible media that includes code for execution and when executed by a processor operable to perform operations comprising:

receiving at least one relative interference statistic from each of a plurality of cells, the at least one relative interference statistic associated with a relative interference of downlink transmission from the cell to a plurality of user equipment devices associated with the cell;

determining a power level for each of one or more resources within a fractional frequency reuse portion of a frequency spectrum based upon the at least one relative interference statistic received from each of the plurality of cells; and

determining a power level for a reuse one portion of the frequency spectrum based upon the determined power level for each of the one or more resources within the fractional frequency reuse portion of the frequency spectrum.

10. The media of claim 9, wherein receiving the at least one relative interference statistic includes:

receiving a total number of user equipment devices connected to each of the plurality of cells;

receiving a total number of user equipment devices for each cell satisfying a first condition in which a neighboring cell Reference Signal Received Power (RSRP) value is at least equal a serving cell RSRP value plus a predetermined minimum relative interference value; and

receiving relative RSRP values for each cell satisfying the first condition.

11. The media of claim 10, wherein determining a power level for each of the one or more resources within the fractional frequency reuse portion includes:

ordering the user equipment devices in each of the plurality of cells decreasing order of their relative RSRP values;

computing signal-to-interference-plus-noise ratio (SINR) values for each of the user equipment devices based on the received relative RSRP values;

discarding the user equipment devices having an SINR value below a predetermined percentile value; and

determining a power level value of at least one resource within the fractional frequency reuse portion of a frequency spectrum based upon a predetermined selection criterion utilizing non-discarded user equipments within the predetermined percentile.

12. The method of claim 11, wherein the operations further comprise:

determining a power level value of a resource within a reuse one portion of the frequency spectrum based upon the determined power level of the at least one resource within the fractional frequency reuse portion.

13. The method of claim 10, further comprising:

ordering a set of user equipment device and interfering cell pairs in decreasing order of relative RSRP from an interfering cell with respect to a serving cell;

determining the pairs from the set with a serving cell RSRP less than a interfering cell RSRP plus a predetermined threshold value;

discarding user equipment devices from the set with a highest of a predetermined percentile of RSRP for neighboring cells; and

determining a power level value of at least one resource within the fractional frequency reuse portion of the frequency spectrum based upon a predetermined selection criterion utilizing non-discarded user equipments within the predetermined percentile.

14. The method of claim 9, wherein receiving the at least one relative interference statistic includes:

receiving relative Reference Signal Received Power (RSRP) values from each of the plurality of cells, wherein the relative RSRP values are ordered in descending order of a number of user equipment devices associated with the cell having a maximum value of relative interference such that the strongest interfering cell RSRP is equal to at least a serving cell RSRP plus a predetermined relative interference value;

ordering the cells in descending order of the number of neighbors of the cells within a predetermined percentile; and

determining relative power levels for each of one or more resources within a fractional frequency reuse portion of a frequency spectrum chosen such that when a particular cell transmits at a first power level and neighboring cells transmit at a second power level, a resulting interference is lowered to a predetermined threshold level below a serving cell power for cells within the predetermined percentile.

15. The media of claim 14, wherein the operations further comprise determining a power level value of the at least one resource within the fractional frequency reuse portion of the frequency spectrum based upon the relative power levels.

16. The media of claim 15, wherein the operations further comprise determining a power level value of a resource within a reuse one portion of the frequency spectrum based upon the determined power level of the at least one resource within the fractional frequency reuse portion.

17. An apparatus, comprising:

a memory element configured to store data,

a processor operable to execute instructions associated with the data, and

at least one module being configured to;

receive at least one relative interference statistic from each of a plurality of cells, the at least one relative interference statistic associated with a relative interference of downlink transmission from the cell to a plurality of user equipment devices associated with the cell;

determine a power level for each of one or more resources within a fractional frequency reuse portion of a frequency spectrum based upon the at least one relative interference statistic received from each of the plurality of cells; and

determine a power level for a reuse one portion of the frequency spectrum based upon the determined power level for each of the one or more resources within the fractional frequency reuse portion of the frequency spectrum.

18. The apparatus of claim 17, wherein receiving the at least one relative interference statistic includes:

receiving a total number of user equipment devices connected to each of the plurality of cells;

receiving a total number of user equipment devices for each cell satisfying a first condition in which a neighboring cell Reference Signal Received Power (RSRP) value is at least equal a serving cell RSRP value plus a predetermined minimum relative interference value; and

receiving relative RSRP values for each cell satisfying the first condition.

19. The apparatus of claim 17, wherein determining a power level for each of the one or more resources within the fractional frequency reuse portion includes:

ordering the user equipment devices in each of the plurality of cells decreasing order of their relative RSRP values;

computing signal-to-interference-plus-noise ratio (SINR) values for each of the user equipment devices based on the received relative RSRP values;

discarding the user equipment devices having an SINR value below a predetermined percentile value; and

determining a power level value of at least one resource within the fractional frequency reuse portion of a frequency spectrum based upon a predetermined selection criterion utilizing non-discarded user equipments within the predetermined percentile.

20. The apparatus of claim 19, wherein the at least one module is further configured to:

determine a power level value of a resource within a reuse one portion of the frequency spectrum based upon the determined power level of the at least one resource within the fractional frequency reuse portion.