Hybrid open/closed loop filtering for link quality estimation

• US 7,403,780 B2
• Filed: 02/19/2004
• Issued: 07/22/2008
• Est. Priority Date: 02/19/2004
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Stevens, James A., Young, C. David, VanLaningham, Steven L., Barton, Jeffrey A., Parekh, Hersh B.
• Primary Examiner(s): TRINH, TAN H
• Application Number:
  US10/782,716
• Publication Number:
  US 20050186963A1
• Time in Patent Office: 1,615 Days
• Field of Search: 455/522, 455/69, 455/403, 455/435.2, 455/238.1, 455/423, 455/452.2, 455/453, 455/452.1, 455/450, 370/342, 370/222
• US Class Current: 455/452.1
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0019 in which mode-switching is based on a statistical approach
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/0222 Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04W 52/262 taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001

Abstract

A method of adapting a communication link in a network of radio communication nodes is disclosed, The method includes sending by a first node a first radio communication, The method also includes receiving by a second node the first radio communication, Further, the method includes estimating by the second node the dynamics of the communications channel, Further still, the method includes categorizing the dynamics of the communications channel into one of at least two groups, based on the estimate, Yet further still the method includes selecting, based on the chosen group, the use of either closed loop link adaption or open loop adaption of communication link parameters.

Claims

1. A method of adapting a communication link in a network of radio communication nodes based on open loop and closed loop communication between a first node and a monitoring node, comprising:

receiving by the monitoring node a first radio communication and a second radio communication from the first node, wherein the first radio communication is open loop and the second radio communication is closed loop;

estimating by the monitoring node the dynamics of a communications channel based on a link metric of at least the first radio communication and the second radio communication;

categorizing the dynamics of the communications channel into one of at least a first state, a second state and a third state, based on the estimate; and

selecting, based on a chosen state, the weighted use of closed loop link adaptation and open loop link adaptation of communication link parameters.

2. The method of claim 1, wherein the at least first, second and third states include at least one of a static state, and a dynamic state.

3. The method of claim 1, wherein the weighted use of communication link parameters is table driven.

4. The method of claim 1, wherein one or more link metrics are normalized based on one or more communication link parameters.

5. The method of claim 4, wherein the at least one or more of the communication parameters is communicated to the monitoring node from the first node in the first radio communication.

6. The method of claim 1, wherein the link metric includes at least one of a received signal strength indicator (RSSI), a signal to noise ratio (SNR), and a symbol error rate (SER).

7. The method of claim 1, wherein the first radio communication includes a message header with a transmission power indicator.

8. The method of claim 1, wherein the communication link parameters comprise at least one of transmit power, modulation type, and forward error correction (FEC).

9. The system of claim 1, further comprising sending by the first node the first radio communication to at least a second node.

10. A method of changing communication link adaptation techniques in a network of radio communication nodes, comprising:

detecting interference by utilizing a monitoring node that receives communication signals in an open loop mode;

estimating, using an open loop estimator, a channel dynamic;

categorizing the channel dynamic into one of at least a first state, a second state and a third state, based on the estimate; and

determining, based on a chosen state, the degree to which transmission parameters should be adjusted by open loop metrics and closed loop metrics.

11. The method of claim 10, further comprising:

adjusting the transmission parameters predominantly based on open loop metrics when the first state the chosen state.

12. The method of claim 10, further comprising:

adjusting the transmission parameters predominantly based on closed loop metrics when the second state the chosen state.

13. The method of claim 10, further comprising:

adjusting the transmission parameters based on both open loop metrics and closed loop metrics when the third state the chosen state.

14. The method of claim 10, wherein the degree to which transmission parameters should be adjusted by open loop metrics and closed loop metrics is table driven.

15. The method of claim 10, wherein the open loop estimator uses at least one of a received signal strength indicator (RSSI), a signal to noise ratio (SNR), and a symbol error rate (SER).

16. The method of claim 10, further comprising:

receiving a radio communication having a message header with a transmission power indicator.

17. The method of claim 10, wherein the transmission parameters comprise at least one of transmit power, modulation type, and forward error correction (FEC).

18. A monitoring node in a radio node communication system, wherein the monitoring node is configured to receive a first radio communication from a first node, the monitoring node comprising:

an estimator module for estimating the dynamics of a communications channel based on a link metric of at least the first radio communication;

a categorization module coupled to the estimator module and configured to categorize the dynamics of the communications channel into one of at least a first state, a second state and a third state, based on the estimate; and

an adaptation module coupled to the categorization module and configured to select based on a chosen state, the weighted use of closed loop link adaptation and open loop link adaptation of communication link parameters.

19. The system of claim 18, wherein the transmission parameters comprise at least one of transmit power, modulation type, and forward error correction (FEC).

20. The system of claim 18, wherein the weighted use of communication link parameters is table driven.

21. The system of claim 18, wherein the estimate utilizes transmission power indicator information from the first radio node.