Slow Adaptation of Modulation and Coding for Packet Transmission

• US 20080267168A1
• Filed: 04/27/2007
• Published: 10/30/2008
• Est. Priority Date: 04/27/2007
• Status: Abandoned Application

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Womack, James Earl, Wu, Wei, Cai, Zhijun
• Application Number:
  US11/741,571
• Publication Number:
  US 20080267168A1
• Time in Patent Office: Days
• US Class Current: 370/352
• 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 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0034 where the transmitter decides based on inferences, e.g. use of implicit signalling
• CPC Class Codes: H04L 1/1692 Physical properties of the supervisory signal, e.g. acknowledgement by energy bursts
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

Systems and methods for performing MCS adaptation are provided. In some cases, the network performs MCS adaptation based on received ACKs.

Claims

1. A method comprising:

transmitting packets to a receiver using an MCS (modulation and coding scheme);

receiving ACKs (acknowledgement) in respect of packets transmitted to the receiver;

determining an updated MCS (modulation and encoding scheme) used to transmit subsequent packets to the receiver as a function of the number of received ACKs.

2. The method of claim 1 further comprising:

signaling the updated MCS to the receiver.

3. The method of claim 1 wherein adapting an MCS (modulation and encoding scheme) used to transmit the sequence of packets as a function of the number of received acknowledgements comprises:

counting a number of ACKs received over a time period.

4. The method of claim 3 wherein updating an MCS (modulation and encoding scheme) used to transmit the sequence of packets as a function of the number of received acknowledgements further comprises:

moving to a more aggressive MCS if the number of ACKs received over the time period exceeds a first threshold;

moving to a less aggressive MCS if the number of ACKs received over the time period is less than a second threshold.

5. The method of claim 1 comprising:

performing said transmitting, receiving and determining for each of a plurality of receivers;

wherein the MCS is adjusted independently for each receiver.

6. The method of claim 1 comprising:

performing said transmitting, receiving and determining for each of a plurality of receivers;

initially assigning each receiver to one of a plurality of groups of receivers, each group having a respective MCS;

wherein moving to a more aggressive MCS for a given receiver and moving to a less aggressive MCS for a given receiver comprise changing the group assigned to the receiver.

7. The method of claim 3 wherein the time period is at least 400 ms.

8. The method of claim 3 wherein the time period comprises a sliding window.

9. The method of claim 1 wherein transmitting packets comprises transmitting a sequence of VoIP packets.

10. The method of claim 1 wherein adapting an MCS (modulation and encoding scheme) used to transmit subsequent packets to the receiver as a function of the number of received ACKs further comprises:

assigning an initial MCS to the receiver based on initial feedback.

11. The method of claim 1 wherein receiving ACKs (acknowledgements) in respect of packets transmitted to the receiver is performed using an ACK-only signalling scheme.

12. The method of claim 2 wherein signaling to the receiver about the updated MCS comprises:

signaling using at least one of layer 2 or above signalling, optional field of a Media Access Control header, and physical layer signalling.

13. The method of claim 1 further comprising signalling new packet notification using at least one of group ID, bitmap, and resource index.

14. A computer readable medium having computer readable instructions stored thereon for implementing the method of claim 1.

15. An arrangement of one or more wireless network components comprising:

at least one antenna;

a transmitter that transmits packets to a wireless device using an MCS (modulation and coding scheme);

a receiver that receives ACKs (acknowledgements) in respect of packets sent to the wireless device;

an MCS adaptor that updates the MCS used to transmit to the wireless device based on a number of ACKs received by the wireless device.

16. The arrangement of claim 15 wherein the receiver receives ACKs in respect of packets transmitted to the wireless device as part of an ACK-only feedback scheme, the arrangement further comprising:

an ACK-only feedback processor that performs retransmissions as a function of the number of received ACKs.

17. A method comprising:

a receiver receiving packets sent to the receiver over a wireless channel in respect of which there is no ACK/NACK feedback channel;

the receiver making a channel quality measurement in respect of the wireless channel;

the receiver determining link adaptation information based on the channel quality measurement;

the receiver feeding back the link adaptation information in a slow rate manner using layer 2 or above signalling.

18. The method of claim 17 wherein the wireless channel is a broadcast channel.

19. The method of claim 17 wherein the receiver feeding back the link adaptation information in a slow rate manner comprises transmitting at least every 400 ms.

20. The method of claim 17 wherein the receiver feeding back link adaptation information comprises:

feeding back a first signal to indicate that a more aggressive MCS should be used;

feeding back a second signal to indicate that a less aggressive MCS should be used; and

feeding back a third signal to indicate that no change in the MCS should be made.

21. An arrangement of one or more wireless network components comprising:

at least one antenna;

a transmitter that transmits packets to a wireless device using an MCS (modulation and coding scheme);

a receiver that receives link adaptation information from the wireless device;

an MCS adaptor that updates the MCS used to transmit subsequent packets to the wireless device based on the adaptation information received from the wireless device.

22. The arrangement of claim 21 wherein:

the transmitter transmits the packets to the wireless device and other wireless devices as part of a broadcast transmission;

the receiver receives link adaptation information from the wireless device and the other wireless devices;

the MCS adaptor updates the MCS used to transmit subsequent packets to the wireless device and the other wireless devices based on the adaptation information received from the wireless devices.

23. The arrangement of claim 22 wherein the receiver receives link adaptation information using layer 2 or above signaling.