Methods and systems for adaptive channel estimation/prediction filter design

• US 9,432,221 B2
• Filed: 06/29/2015
• Issued: 08/30/2016
• Est. Priority Date: 07/23/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Cili, Gencer
• Primary Examiner(s): Oveissi, David
• Application Number:
  US14/754,423
• Publication Number:
  US 20150304132A1
• Time in Patent Office: 428 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0222 Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

A method to adapt a set of multi-point channel estimation filters for use in wireless communications including measuring a plurality of reception values is provided. Each reception value included in the plurality of reception values associated with one of the network nodes. The method includes sorting the plurality of reception values according to magnitude and determining a select reception value. The method includes selecting a particular network node from the set of network nodes based on the reception value. The reception value is within a threshold from the select reception value. The method includes adjusting the length of a multi-point channel estimation filter associated with the particular network node. The adjusting the length is based on a lookup table and on the reception value associated with the particular network node, according to some embodiments. User equipment in a wireless network adapted for the above method is also provided.

Claims

1. A method to adapt filter lengths for a set of channel estimation filters for use in a wireless communication device, the method comprising:

by the wireless communication device;

tracking a plurality of network nodes in a joint transmission set;

providing a two-dimensional circular buffer for storing reception values for signals received from the plurality of network nodes in the joint transmission set over a time window;

determining a moving average of a plurality of stored reception values for a particular network node included in the joint transmission set;

determining one or more transmission time intervals (TTIs) for each network node actively participating in at least a previous joint transmission set; and

adapting a filter length for the particular network node in the joint transmission set based at least in part on the moving average of the plurality of stored reception values for the particular network node.

2. The method of claim 1, further comprising selecting, by the wireless communication device, a plurality of network nodes to include in a future joint transmission set.

3. The method of claim 2, further comprising:

by the wireless communication device;

determining a coherence time for a transmission channel between the particular network node in the joint transmission set and the wireless communication device; and

selecting a particular time window associated with the particular network node,

wherein a length of the particular time window is less than the coherence time for the transmission channel, and

wherein the wireless communication device determines the moving average of the plurality of stored reception values for the particular node in the transmission set using the particular time window associated with the particular network node.

4. The method of claim 3, wherein the wireless communication device determines the coherence time based at least in part on a velocity of the wireless communication device.

5. The method of claim 1, wherein adapting the filter length for the particular network node in the joint transmission set based at least in part on the moving average comprises determining a historical recurrence of the particular network node in the previous joint transmission set.

6. The method of claim 1, wherein the filter length comprises a length of a multi-point channel estimation filter associated with the particular network node in the joint transmission set.

7. The method of claim 1, further comprising:

by the wireless communication device;

selecting a size of the two-dimensional circular buffer based at least in part on a calculated coherence time value for the wireless communication device determined based at least in part on a velocity of the wireless communication device.

8. The method of claim 7, further comprising:

by the wireless communication device;

determining a correlation function using the stored reception values,

wherein the wireless communication device calculates the coherence time based at least in part on the correlation function.

9. The method of claim 8, wherein determining the correlation function using the stored reception values comprises determining one or more channel impulse responses for one or more transmission channels between the wireless communication device and the plurality of network nodes in the joint transmission set.

10. A wireless communication device configurable for operation in a wireless network, the wireless communication device comprising:

wireless circuitry comprising at least a transmitter and a receiver;

memory configured to store instructions; and

one or more processors in communication with the wireless circuitry and the memory configured to, upon execution of the instructions, cause the wireless communication device to;

track a plurality of network nodes in a joint transmission set;

provide a two-dimensional circular buffer for storing reception values for signals received from the plurality of network nodes in the joint transmission set over a time window;

determine a moving average of a plurality of stored reception values for a particular network node included in the joint transmission set;

determine one or more transmission time intervals (TTIs) for each network node actively participating in at least a previous joint transmission set; and

adapt a filter length for the particular network node in the joint transmission set based at least in part on the moving average of the plurality of stored reception values for the particular network node.

11. The wireless communication device of claim 10, wherein execution of the instructions further causes the wireless communication device to select a plurality of network nodes to include in a future joint transmission set.

12. The wireless communication device of claim 11, wherein execution of the instructions further causes the wireless communication device to:

determine a coherence time for a transmission channel between the particular network node in the joint transmission set and the wireless communication device; and

select a particular time window associated with the particular network node,

wherein a length of the time window is less than the coherence time for the transmission channel, and

wherein the wireless communication device determines the moving average of the plurality of stored reception values for the particular node in the transmission set using the particular time window associated with the particular network node.

13. The wireless communication device of claim 12, wherein the wireless communication device determines the coherence time based at least in part on a velocity of the wireless communication device.

14. The wireless communication device of claim 10, wherein the wireless communication device adapts the filter length for the particular network node in the joint transmission set based at least in part on the moving average by at least determining a historical recurrence of the particular network node in the previous joint transmission set.

15. The wireless communication device of claim 10, wherein the filter length comprises a length of a multi-point channel estimation filter associated with the particular network node in the joint transmission set.

16. The wireless communication device of claim 10, wherein execution of the instructions further causes the wireless communication device to:

select a size of the two-dimensional circular buffer based at least in part on a calculated coherence time value for the wireless communication device determined based at least in part on a velocity of the wireless communication device.

17. The wireless communication device of claim 16, wherein execution of the instructions further causes the wireless communication device to:

determine a correlation function using the stored reception values,

wherein the wireless communication device calculates the coherence time based at least in part on the correlation function.

18. The wireless communication device of claim 17, wherein the wireless communication device determines the correlation function using the stored reception values by at least determining one or more channel impulse responses for one or more transmission channels between the wireless communication device and the plurality of network nodes in the joint transmission set.

19. A non-transitory computer-readable medium storing executable instructions that, when executed by one or more processors of a wireless communication device, cause the wireless communication device to:

track a plurality of network nodes in a joint transmission set;

provide a two-dimensional circular buffer for storing reception values for signals received from the plurality of network nodes in the joint transmission set over a time window;

determine a moving average of a plurality of stored reception values for a particular network node included in the joint transmission set;

determine one or more transmission time intervals (TTIs) for each network node actively participating in at least a previous joint transmission set; and

adapt a filter length for the particular network node in the joint transmission set based at least in part on the moving average of the plurality of stored reception values for the particular network node.

20. The non-transitory computer-readable medium of claim 19, wherein execution of the instructions further causes the wireless communication device to:

select a plurality of network nodes to include in a future joint transmission set.