Method and device for rank adaptation

• US 8,755,810 B2
• Filed: 03/05/2010
• Issued: 06/17/2014
• Est. Priority Date: 08/19/2009
• Status: Active Grant

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Tan, Yuanchun, Peng, Focai, Liu, Liping, Li, Xianxi, Li, Liang, Liu, Juanjuan
• Primary Examiner(s): WYCHE, MYRON
• Application Number:
  US13/258,557
• Publication Number:
  US 20120196612A1
• Time in Patent Office: 1,565 Days
• Field of Search: 455/452.1, 455/507, 375/224, 375/260, 370/329
• US Class Current: 455/452.1
• CPC Class Codes: H04B 7/0486 taking channel rank into account
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/563 of the wireless resources

Abstract

The present invention discloses a method and apparatus for rank self-adaptation. The method comprises: a base station receiving ranks reported by a user equipment via a rank receiving window, determining a rank at the current moment based on a distribution state of each rank in the rank receiving window at the current moment, and determining the number of independent channels used for sending downstream data to the user equipment based on the rank at the current moment. The present invention can reasonably forecast change of ranks of MIMO channels so as to better use MIMO channel resources to perform data transmission and improve the throughput rate of the MIMO channels.

Claims

1. A method for rank self-adaptation based on pre-defined distribution states of ranks, the method comprising:

a base station receiving ranks reported by a user equipment via a rank receiving window, determining a rank at the current moment based on one of the pre-defined distribution states of ranks to which a distribution state of each rank in the rank receiving window at the current moment belongs, and determining the number of independent channels used for sending downstream data to the user equipment based on the rank at the current moment;

wherein in the step of determining the rank at the current moment;

when the number of ranks in the rank receiving window is greater than a threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 2, the base station takes a rank newly reported by the user equipment in the rank receiving window as the rank at the current moment;

wherein state 2 means that;

when the smallest value N_maxS among the number of receiving antennas and the number of transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x and continuous y, where values of x and y differ by 1, and the number of y is greater than or equal to the number of x;

or

when N_maxS is equal to 8, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x, continuous y and continuous z, where difference values of x, y, z in turn are 1, values of x, y, z in turn increase or decrease, and the total number of y and z is greater than or equal to the number of x, and the number of z is greater than or equal to the number of y.

2. The method according to claim 1, wherein in the step of determining the rank at the current moment:

when the number of the ranks in the rank receiving window is greater than the threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 3, state 3 means that the ranks in the rank receiving window in turn are continuous x and one y, the absolute difference value between y and x is m, m is greater than or equal to 1 and is less than or equal to N_maxS−

1, N_maxS is the smallest value among the number of the receiving antennas and the number of the transmitting antennas; and

the base station is further configured to;

when the difference value between y and x is less than 0, take the newly reported rank in the rank receiving window as the rank at the current moment;

when the difference value between y and x is greater than 0 and the user equipment is located at an edge of a cell to which the user equipment belongs, take 1 as the rank at the current moment; and

when the difference value between y and x is greater than 0 and the user equipment is not located at the edge of the cell to which the user equipment belongs, take x+1 as the rank at the current moment.

3. The method according to claim 2, wherein in the step of determining the rank at the current moment:

when the number of the ranks in the rank receiving window is greater than the threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 4, state 4 means that the ranks in the rank receiving window in turn are continuous x and y, x is not equal to y, the number of y is less than the number of x, and the number of y is greater than or equal to n, and n is greater than or equal to 2; and

the base station is further configured to;

when the value of y is less than x, take the newly reported rank in the rank receiving window as the rank at the current moment;

when the value of y is greater than or equal to x and the user equipment is located at the edge of the cell to which the user equipment belongs, take 1 as the rank at the current moment; and

when the value of y is greater than or equal to x and the user equipment is not located at the edge of the cell to which the user equipment belongs, take the newly reported rank in the rank receiving window as the rank at the current moment.

4. The method according to claim 2, wherein

the user equipment being located at the edge of the cell to which the user equipment belongs means that reference signal received power of the cell reported by the user equipment is less than or equal to a reference signal received power threshold of the cell configured by a system;

and

the user equipment being not located at the edge of the cell to which the user equipment belongs means that the reference signal received power of the cell reported by the user equipment is greater than the reference signal received power threshold of the cell configured by the system.

5. The method according to claim 1, wherein in the step of determining the rank at the current moment:

when the number of the ranks in the rank receiving window is greater than the threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 5, the base station takes the smallest rank in the rank receiving window as the rank at the current moment;

state 5 means that when the smallest value N_maxS among the number of the receiving antennas and the number of the transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are an alternate sequence of x and y, the value of y and the value of x differ by 1;

or

when N_maxS is equal to 8, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window comprise x and y and there are no continuous x and y, the value of y and the value of x differ by 1 or 2, or the ranks in the rank receiving window comprise x, y and z, and one of x, y and z is adjacent to the other two.

6. The method according to claim 1, wherein in the step of determining the rank at the current moment:

when the number of the ranks in the rank receiving window is greater than the threshold A, and the smallest value N_maxS among the number of the receiving antennas and the number of the transmitting antennas is greater than or equal to 2 and is less than or equal to 3, and when the distribution state of each rank in the rank receiving window at the current moment does not meet state 1, state 2, state 3 and state 4, takes 1 as the rank at the current moment;

state 1 means that the value of each rank in the rank receiving window is the same;

state 2 means that distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x and continuous y, where the value of x and the value of y differ by 1, the number of y is greater than or equal to the number of x;

state 3 means that the ranks in the rank receiving window in turn are continuous x and one y, the absolute difference value between y and x is in, m is greater than or equal to 1 and is less than or equal to N_maxS−

1; and

state 4 means that the ranks in the rank receiving window in turn are continuous x and y, x is not equal to y, the number y is less than the number of x, and the number of y is greater than or equal to n, and n is greater than or equal to 2.

7. The method according to claim 1, wherein in the step of determining the rank at the current moment:

when the number of the ranks in the rank receiving window is greater than the threshold A, and the smallest value N_maxS among the number of the receiving antennas and the number of the transmitting antennas is greater than or equal to 4, and when the distribution state of each rank in the rank receiving window at the current moment does not meet state 1, state 2, state 3, state 4 and state 5, the base station takes the smallest rank in the rank receiving window as the rank at the current moment;

state 1 means that the value of each rank in the rank receiving window is the same;

state 2 means that when N_maxS is greater than or equal to 4 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x and continuous y, the value of x and the value of y differ by 1, and the number of y is greater than or equal to the number of x;

or when N_maxS is equal to 8, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x, continuous y and continuous z, where difference values between x, y, z in turn are 1, values of x, y, z in turn increase or decrease, and the total number of y and z is greater than or equal to the number of x, the number of z is greater than or equal to the number of y;

state 3 means that the ranks in the rank receiving window in turn are continuous x and one y, the absolute difference value between y and x is m, m is greater than or equal to 1 and is less than or equal to N_maxS−

1;

state 4 means that the ranks in the rank receiving window in turn are continuous x and y, x is not equal to y, the number of y is less than the number of x, and the number of y is greater than or equal to n, and n is greater than or equal to 2; and

state 5 means that when N_maxS is greater than or equal to 4 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are an alternate sequence of x and y, the value of y and the value of x differ by 1;

or when N_maxS is equal to 8, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window comprise x and y and there is no continuous x and y, the value of y and the value of x differ by 1 or 2, or the ranks in the rank receiving window comprise x, y and z and one of the x, y and z is adjacent to the other two.

8. The method according to claim 1, wherein in the step of determining the rank at the current moment:

when the number of the ranks in the rank receiving window is less than the threshold A, the base station takes the smallest rank in the rank receiving window as the rank at the current moment.

9. The method according to claim 1, wherein the threshold A is an integer greater than or equal to 3.

14. The method according to claim 3, wherein

the user equipment being located at the edge of the cell to which the user equipment belongs means that reference signal received power of the cell reported by the user equipment is less than or equal to a reference signal received power threshold of the cell configured by a system;

and

the user equipment being not located at the edge of the cell to which the user equipment belongs means that the reference signal received power of the cell reported by the user equipment is greater than the reference signal received power threshold of the cell configured by the system.

15. The method according to claim 2, wherein the threshold A is an integer greater than or equal to 3.

16. The method according to claim 3, wherein the threshold A is an integer greater than or equal to 3.

17. The method according to claim 5, wherein the threshold A is an integer greater than or equal to 3.

18. The method according to claim 6, wherein the threshold A is an integer greater than or equal to 3.

10. An apparatus for rank self-adaptation based on pre-defined distribution states of ranks, the apparatus comprising:

a connected rank receiving unit and a rank determining unit;

the rank receiving unit is configured to receive ranks reported by a user equipment via a rank receiving window to send to the rank determining unit; and

the rank determining unit is configured to determine a rank at the current moment based on one of the pre-defined distribution states of ranks to which a distribution state of each rank in the rank receiving window at the current moment belongs, and determine the number of independent channels used for sending downstream data to the user equipment based on the rank at the current moment;

wherein

the rank determining unit is further configured to, when determining that the number of ranks in the rank receiving window is greater than a threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 2, take a rank newly reported by the user equipment in the rank receiving window as the rank at the current moment;

wherein state 2 means that;

when the smallest value N_maxS among the number of receiving antennas and the number of transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x and continuous y, where values of x and y differ by 1, and the number of y is greater than or equal to the number of x;

or

when N_maxS is equal to 8, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are continuous x, continuous y and continuous z, where difference values of x, y, z in turn are 1, values of x, y, z in turn increase or decrease, and the total number of y and z is greater than or equal to the number of x, and the number of z is greater than or equal to the number of y.

11. The apparatus according to claim 10, further comprising a user equipment position measurement unit connected to the rank determining unit, wherein

the user equipment position measurement unit is configured to measure whether the user equipment is located at an edge of a cell to which the user equipment belongs;

the rank determining unit is further configured to;

when determining that the number of the ranks in the rank receiving window is greater than the threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 3, state 3 meaning that the ranks in the rank receiving window in turn are continuous x and one y, the absolute difference value between y and x is m, m is greater than or equal to 1 and is less than or equal to N_maxS−

1, and N_maxS is the smallest value among the number of the receiving antennas and the number of the transmitting antennas,

when determining that the difference value between y and x is less than 0, take the newly reported rank in the rank receiving window as the rank at the current moment; and

when determining that the difference value between y and x is greater than 0, obtain information whether the user equipment is located at the edge of the cell to which the user equipment belongs from the user equipment position measurement unit, and determine the rank at the current moment based on the position of the user equipment;

when the user equipment is located at the edge of the cell to which the user equipment belongs, take 1 as the rank at the current moment; and

when the user equipment is not located at the edge of the cell to which the user equipment belongs, take x+1 as the rank at the current moment.

12. The apparatus according to claim 11, further comprising the user equipment position measurement unit connected to the rank determining unit, wherein

the user equipment position measurement unit is configured to measure whether the user equipment is located at the edge of the cell to which the user equipment belongs;

the rank determining unit is further configured to;

when determining that the number of the ranks in the rank receiving window is greater than the threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 4, state 4 meaning that the ranks in the rank receiving window in turn are continuous x and y, x is not equal to y, the number of y is less than the number of x, and the number of y is greater than or equal to n, and n is greater than or equal to 2,

when determining that the value of y is less than x, take the newly reported rank in the rank receiving window as the rank at the current moment; and

when determining that the value of y is greater than or equal to x, obtain information whether the user equipment is located at the edge of the cell to which the user equipment belongs from the user equipment position measurement unit, and determine the rank at the current moment based on the position of the user equipment;

when the user equipment is located at the edge of the cell to which the user equipment belongs, take 1 as the rank at the current moment; and

when the user equipment is not located at the edge of the cell to which the user equipment belongs, take the newly reported rank in the rank receiving window as the rank at the current moment.

13. The apparatus according to claim 10, wherein

the rank determining unit is further configured to, when determining that the number of the ranks in the rank receiving window is greater than the threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 5, take the smallest rank in the rank receiving window as the rank at the current moment;

state 5 means that when the smallest value N_maxS among the number of the receiving antennas and the number of the transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window in turn are an alternate sequence of x and y, the value of y and the value of x differ by 1;

or when N_maxS is equal to 8, distribution of each rank in the rank receiving window meets the following conditions;

the ranks in the rank receiving window comprise x and y and there are no continuous x and y, the value of y and the value of x differ by 1 or 2, or the ranks in the rank receiving window comprise x, y, and z, and one of x, y, and z is adjacent to the other two.