Adaptive Switching Techniques for Hybrid Automatic Repeat Request Systems

• US 20080240208A1
• Filed: 03/25/2008
• Published: 10/02/2008
• Est. Priority Date: 03/26/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Jin, Hang, Hedayat, Ahmadreza, Wang, Genyuan, Lou, Hanqing
• Granted Patent: US 8,121,211 B2
• Time in Patent Office: Days
• US Class Current: 375/211
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1825 Adaptation of specific ARQ protocol parameters according to transmission conditions
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

Apparatus, system, and method for an adaptive transmission selection technique. A retransmission scheme is selected for a multiple-input-multiple-output (MIMO) wireless communications system. Techniques are provided herein for selecting from a plurality of wireless communication techniques when a first device needs to retransmit a signal (one or more packets of data) to a second device. The first device determines when the signal which was originally wirelessly transmitted using beamforming techniques via multiple antennas of the first device to the second device needs to be retransmitted to the second device. If a retransmission is needed, the first device determines channel conditions with respect to the second device. The first device selects a retransmission scheme from a plurality of transmission schemes based on the channel conditions for retransmitting the signal via the multiple antennas of the first device to the second device. A first retransmission technique is selected when the channel conditions are static. A second retransmission technique is selected when the channel conditions are relatively slowly changing, and a third retransmission technique is selected when the channel conditions are relatively quickly changing.

Claims

1. A method comprising:

determining when a signal which was originally wirelessly transmitted using beamforming techniques via multiple antennas of a first device to a second device needs to be retransmitted to the second device;

determining channel conditions between the first device and the second device; and

selecting a retransmission scheme from a plurality of transmission schemes based on the channel conditions when retransmitting the signal via the multiple antennas of the first device to the second device.

2. The method of claim 1, wherein determining when the signal needs to be retransmitted comprises receiving at the first device a request from the second device for retransmitting the signal.

3. The method of claim 1, wherein determining when the signal needs to be retransmitted comprises not receiving at the first device a reception acknowledgment from the second device indicating that the second device received the signal.

4. The method of claim 1, wherein determining channel conditions comprises determining whether the channel conditions between the first device and the second device are either static, relatively slowly changing or relatively quickly changing.

5. The method of claim 4, wherein when it is determined that the channel conditions are static, selecting comprises selecting the beamforming technique for retransmitting the signal from the first device to the second device.

6. The method of claim 5, and further comprising retransmitting the signal from the first device to the second device using beamforming weights that were used when the signal was originally transmitted.

7. The method of claim 4, wherein when it is determined that the channel conditions are relatively quickly changing, selecting comprises selecting a cyclic delay diversity transmission scheme for an orthogonal frequency division multiple access (OFDMA) signal in which subcarriers are grouped into clusters, and a set of clusters is assigned to a particular device, and wherein the cyclic delay diversity transmission scheme applies cluster specific rotation coefficients to the clusters assigned to the second device that result in corresponding delays for subcarriers transmitted by corresponding ones of the multiple antennas of the first device to the second device.

8. The method of claim 7, and further comprising determining the cluster specific rotation coefficients based on the channel conditions.

9. The method of claim 4, wherein when it is determined that the channel conditions are relatively slowly changing, selecting comprises selecting a cluster-based transmit antenna selection group transmission scheme for an orthogonal frequency division multiple access (OFDMA) signal in which subcarriers are grouped into clusters, and a set of clusters is assigned to a particular device, and wherein the cluster-based transmit antenna selection group transmission scheme applies weights to the set of clusters associated with the second device that result in each cluster being transmitted by zero or more of the multiple antennas of the first device to the second device.

10. The method of claim 9, and further comprising determining the weights applied to the clusters in the cluster-based transmit antenna selection group transmission scheme based on the channel conditions, and wherein the weights are zero or one, or a value between zero and 1.

11. The method of claim 9, wherein the cluster-based transmit antenna selection group transmission scheme results each of the multiple antennas of the first device transmitted only part of a symbol, and further comprising allocating more power to certain clusters.

12. An apparatus, comprising:

a plurality of antennas;

a transmitter coupled to the plurality of antennas and configured to transmit data via the plurality of antennas using any one of a plurality of a multiple-input-multiple-output (MIMO) wireless transmission techniques, at least one of which is a beamforming technique; and

a controller coupled to the transmitter that is configured to determine when a signal which was originally wirelessly transmitted using the beamforming technique to a destination device needs to be retransmitted to the destination device, determine channel conditions with respect to the destination device, and select a scheme from the plurality of MIMO wireless transmission techniques based on the channel conditions for retransmitting the data to the destination device.

13. The apparatus of claim 12, wherein the controller determines when the data needs to be retransmitted by receiving a request from the destination device for retransmitting of the data.

14. The apparatus of claim 12, wherein the controller determines when the data needs to be retransmitted by not receiving a reception acknowledgment from the destination device indicating that the destination device received the data.

15. The apparatus of claim 12, wherein the controller determines whether channel conditions are either static, relatively slowly changing or relatively quickly changing.

16. The apparatus of claim 15, wherein when the controller determines that the channel conditions are static, the controller selects the beamforming technique for retransmitting the data to the destination device.

17. The apparatus of claim 15, wherein when the controller determines that the channel conditions are relatively quickly changing, the controller selects a cyclic delay diversity transmission technique for an orthogonal frequency division multiple access (OFDMA) signal in which subcarriers are grouped into clusters, and a set of clusters is assigned to a particular device, and wherein the cyclic delay diversity transmission scheme applies cluster specific rotation coefficients to the clusters assigned to the destination device that result in corresponding delays for subcarriers transmitted by corresponding ones of the plurality of antennas to the destination device.

18. The apparatus of claim 17, wherein the controller determines the cluster specific rotation coefficients based on the channel conditions.

19. The apparatus of claim 15, wherein when the controller determines that the channel conditions are relatively slowly changing, the controller selects a cluster-based transmit antenna selection group transmission technique for an orthogonal frequency division multiple access (OFDMA) signal in which subcarriers are grouped into clusters, and a set of clusters is assigned to a particular device, and wherein the cluster-based transmit antenna selection group transmission scheme applies weights to the set of clusters associated with the destination device that result in each cluster being transmitted by zero or more of the plurality of antennas to the destination device.

20. The apparatus of claim 19, wherein the controller determines the weights applied to the clusters in the cluster-based transmit antenna selection group transmission technique based on the channel conditions, and wherein the weights are zero or one, or a value between zero and one.

21. The apparatus of claim 19, wherein the controller allocates more power to certain of the clusters.

22. Logic encoded in one or more tangible media for execution and when executed operable to:

determine when a signal which was originally wirelessly transmitted using beamforming techniques via multiple antennas of a first device to a second device needs to be retransmitted to the second device;

determine channel conditions between the first device and the second device; and

select a retransmission scheme from a plurality of transmission schemes based on the channel conditions for retransmitting the signal via the multiple antennas of the first device to the second device.

23. The logic of claim 22, wherein the channel conditions are determined to be either static, relatively slowly changing or relatively quickly changing.

24. The logic of claim 23, wherein the logic that selects the transmission scheme selects the beamforming technique for retransmitting the signal from the first device to the second device when the channel conditions are static.

25. The logic of claim 23, wherein when the channel conditions are relatively fast changing, the logic that selects the transmission scheme selects a cyclic delay diversity transmission scheme for an orthogonal frequency division multiple access (OFDMA) signal in which subcarriers are grouped into clusters, and a set of clusters is assigned to a particular device, and wherein the cyclic delay diversity transmission scheme applies cluster specific rotation coefficients to the clusters assigned to the second device based on the channel conditions that result in corresponding delays for subcarriers transmitted by corresponding ones of the multiple antennas of the first device to the second device.

26. The logic of claim 23, wherein when the channel conditions are relatively slowly changing, the logic that selects the transmission scheme selects a cluster-based transmit antenna selection group transmission scheme for an orthogonal frequency division multiple access (OFDMA) signal in which subcarriers are grouped into clusters, and a set of clusters is assigned to a particular device, and wherein the cluster-based transmit antenna selection group transmission scheme applies weights to the set of clusters associated with the second device based on the channel conditions that result in each cluster being transmitted by zero or more of the multiple antennas of the first device to the second device.