BASE STATION AND METHOD FOR IMPLEMENTING AN ADAPTIVE CLOSED-LOOP MIMO AND OPEN-LOOP MIMO TECHNIQUE IN A WIRELESS COMMUNICATION SYSTEM

• US 20130022142A1
• Filed: 07/20/2011
• Published: 01/24/2013
• Est. Priority Date: 07/20/2011
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nammi, Sairamesh
• Application Number:
  US13/186,605
• Publication Number:
  US 20130022142A1
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme

Abstract

A base station and a method are described herein that implement an adaptive closed-loop MIMO and open-loop MIMO technique which accounts for all channel conditions and improves the performance of communications with a user equipment. In one example, the base station and method analyze a current user equipment report and a previous user equipment report received from a user equipment to determine if at least one channel condition parameter has a rate of change greater than a corresponding at least one threshold and if yes then use an open-loop MIMO technique and if no then use a closed-loop MIMO technique when interacting with the user equipment.

Claims

1. A base station which has multiple antennas and also implements an adaptive closed-loop multiple input multiple output (MIMO) and open-loop MIMO technique, the base station comprising:

a receiver that receives user equipment reports over a period of time from a user equipment;

a processor; and

a memory that stores processor-executable instructions therein where the processor interfaces with the memory and executes the processor-executable instructions to enable the following;

analyze a current user equipment report and a previous user equipment report received from the user equipment to determine if at least one channel condition parameter has a rate of change greater than a corresponding at least one threshold and if yes then use the open-loop MIMO technique when interacting with the user equipment and if no then use the closed-loop MIMO technique when interacting with the user equipment; and

a transmitter that sends a message to the user equipment indicating whether currently utilizing the open-loop MIMO technique or the closed-loop MIMO technique to interact with the user equipment.

2. The base station of claim 1, wherein the at least one channel condition parameter is an average speed of the user equipment.

3. The base station of claim 1, wherein the at least one channel condition parameter is a frequency location change rate associated with the user equipment.

4. The base station of claim 1, wherein the at least one channel condition parameter is a Channel Quality Information (CQI) change rate associated with the user equipment.

5. The base station of claim 1, wherein the at least one channel condition parameter is a Pre-Encoding Matrix Indicator (PMI) change rate associated with the user equipment.

6. The base station of claim 1, wherein the user equipment reports include one or more of following:

a rank information (RI), a L-bit map, a plurality of Channel Quality Information (CQIs), a wideband Pre-Encoding Matrix Indicator (PMI), and a wideband CQI;

a rank information (RI), a L-bit map, a plurality of PMIs, a wideband PMI, and a wideband CQI; and

a rank information (RI), a L-bit map, a plurality of CQIs, and a wideband CQI.

7. The base station of claim 1, wherein the processor executes the process-executable instructions to perform the analyze operation as follows:

start a cycle and wait for a transmit time interval (TTI) to pass;

determine if a monitoring period passed, where the monitoring period has a duration corresponding to a predetermined number of TTIs;

if result of the first determine step is yes, then;

compare the current user equipment report and the previous user equipment report to obtain the at least one channel condition parameter;

determine if the at least one channel condition parameter has a rate of change greater than the corresponding at least one threshold;

if the result of the second determine step is yes, then set a mobile velocity flag to a first value, wait for next TTI to pass, and return to the first determine step;

if the result of the second determine step is no, then set a mobile velocity flag to a second value, wait for next TTI to pass, and return to the first determine step;

if the first determine step is no, then determine if the mobile velocity flag is set to either the first value or the second value;

if the mobile velocity flag is set to the first value, then use the open-loop MIMO technique, wait for the next TTI to pass, and return to the first determine step;

if the mobile velocity flag is set to the second value, then use the closed-loop MIMO technique, wait for the next TTI to pass, and return to the first determine step.

8. A method in a base station which has multiple antennas for implementing an adaptive closed-loop multiple input multiple output (MIMO) and open-loop MIMO technique, the method comprising the steps of:

receiving user equipment reports over a period of time from a user equipment;

analyzing a current user equipment report and a previous user equipment report received from the user equipment to determine if at least one channel condition parameter has a rate of change greater than a corresponding at least one threshold and if yes then use the open-loop MIMO technique when interacting with the user equipment and if no then use the closed-loop MIMO technique when interacting with the user equipment; and

sending a message to the user equipment indicating whether currently utilizing the open-loop MIMO technique or the closed-loop MIMO technique to interact with the user equipment.

9. The method of claim 8, wherein the at least one channel condition parameter is an average speed of the user equipment.

10. The method of claim 8, wherein the at least one channel condition parameter is a frequency location change rate associated with the user equipment.

11. The method of claim 8, wherein the at least one channel condition parameter is a Channel Quality Information (CQI) change rate associated with the user equipment.

12. The method of claim 8, wherein the at least one channel condition parameter is a Pre-Encoding Matrix Indicator (PMI) change rate associated with the user equipment.

13. The method of claim 8, wherein the user equipment reports include one or more of following:

a rank information (RI), a L-bit Map, a plurality of Channel Quality Information (CQIs), a wideband Pre-Encoding Matrix Indicator (PMI), and a wideband CQI;

a rank information (RI), a L-bit map, a plurality of PMIs, a wideband PMI, and a wideband CQI; and

a rank information (RI), a L-bit map, a plurality of CQIs, and a wideband CQI.

14. The method of claim 8, wherein the analyzing step further comprises:

starting a cycle and waiting for a transmit time interval (TTI) to pass;

determining if a monitoring period passed, where the monitoring period has a duration corresponding to predetermined number of TTIs;

if result of the first determining step is yes, then;

comparing the current user equipment report and the previous user equipment report to obtain the at least one channel condition parameter;

determining if the at least one channel condition parameter has a rate of change greater than the corresponding at least one threshold;

if the result of the second determining step is yes, then setting a mobile velocity flag to a first value, waiting for next TTI to pass, and returning to the first determining step;

if the result of the second determining step is no, then setting a mobile velocity flag to a second value, waiting for next TTI to pass, and returning to the first determining step;

if the first determining step is no, then determining if the mobile velocity flag is set to either the first value or the second value;

if the mobile velocity flag is set to the first value, then using the open-loop MIMO technique, waiting for the next TTI to pass, and returning to the first determining step;

if the mobile velocity flag is set to the second value, then using the closed-loop MIMO technique, waiting for the next TTI to piss, and returning to the first determining step.

15. A wireless communication system comprising:

a user equipment that sends user equipment reports over a period of time;

base station which has multiple antennas and also implements an adaptive closed-loop multiple input multiple output (MIMO) and open-loop MIMO technique, the base station comprising;

a receiver that receives the user equipment reports from the user equipment;

a processor; and

a memory that stores processor-executable instructions therein where the processor interfaces with the memory and executes the processor-executable instructions to enable the following;

analyze a current user equipment report and a previous user equipment report received from the user equipment to determine if at least one channel condition parameter has a rate of change greater than a corresponding at least one threshold and if yes then use the open-loop MIMO technique when interacting with the user equipment and if no then use the closed-loop MIMO technique when interacting with the user equipment; and

a transmitter that sends a message to the user equipment indicating whether currently utilizing the open-loop MIMO technique or the closed-loop MIMO technique to interact with the user equipment.

16. The wireless communication system of claim 15, wherein the at least one channel condition parameter includes one or more of following:

an average speed of the user equipment;

a frequency location change rate associated with the user equipment;

a Channel Quality Information (CQI) change rate associated with the user equipment; and

a Pre-Encoding Matrix Indicator (PMI) change rat associated with the user equipment.

17. The wireless communication system of claim 15, wherein the user equipment reports include one or more of following:

a rank information (RI), a L-bit map, a plurality of Channel Quality Information (CQIs), a wideband Pre-Encoding Matrix Indicator (PMI), and a wideband CQI;

a rank information (RI), a L-bit map, a plurality of PMIs, a wideband PMI, and a wideband CQI; and

a rank information (RI), a L-bit map, a plurality of CQIs, and a wideband CQI.

18. The wireless communication system of claim 15, wherein the processor executes the process-executable instructions to perform the analyze operation as follows:

start a cycle and wait for a transmit time interval (TTI) to pass;

determine if a monitoring period passed, where the monitoring period has a duration corresponding to a predetermined number of TTIs;

if result of the first determine step is yes, then;

compare the current user equipment report and the previous user equipment report to obtain the at least one channel condition parameter;

determine if the at least one channel condition parameter has a rate of change greater than the corresponding at least one threshold;

if the result of the second determine step is yes, then set a mobile velocity flag to a first value, wait for next TTI to pass, and return to the first determine step;

if the result of the second determine step is no, then set a mobile velocity flag to a second value, wait for next TTI to pass, and return to the first determine step;

if the first determine step is no, then determine if the mobile velocity flag is set to either the first value or the second value;

if the mobile velocity flag is set to the first value, then use the open-loop MIMO technique, wait for the next TTI to pass, and return to the first determine step;

if the mobile velocity flag is set to the second value, then use the closed-loop MIMO technique, wait for the next TTI to pass, and return to the first determine step.