Outer-loop scheduling design for communication systems with channel quality feedback mechanisms

• US 7,170,876 B2
• Filed: 04/30/2002
• Issued: 01/30/2007
• Est. Priority Date: 04/30/2002
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wei, Yongbin, Puig-Oses, David, Sarkar, Sandip, Holtzman, Jack M., Bao, Gang
• Primary Examiner(s): Kizou; Hassan
• Assistant Examiner(s): Ahmed; Salman
• Application Number:
  US10/136,906
• Publication Number:
  US 20030204615A1
• Time in Patent Office: 1,736 Days
• Field of Search: 370342-343, 370229-236, 370/328, 370/329, 370/335
• US Class Current: 370/335
• 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 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0034 where the transmitter decides based on inferences, e.g. use of implicit signalling
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• 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 1/20 using signal quality detector
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 47/522 Dynamic queue service slot or variable bandwidth allocation
• CPC Class Codes: H04L 47/626 channel conditions
• CPC Class Codes: H04W 28/0231 based on communication conditions dynamic wireless traffic scheduling definition based on channel quality criteria H04W72/54
• CPC Class Codes: H04W 28/0268 using specific QoS parameters for wireless networks, e.g. QoS class identifier [QCI] or guaranteed bit rate [GBR] negotiating SLA or negotiating QoS H04W28/24
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/54 : based on quality criteria
• CPC Class Codes: H04W 72/542 : using measured or perceived quality
• CPC Class Codes: H04W 8/04 : Registration at HLR or HSS [Home Subscriber Server]

Abstract

Methods and apparatus are presented for dynamically adjusting parameters of an outer-loop algorithm, which is used to determine the feasibility of a transmission format. The parameters of the outer-loop algorithm are adjusted according to channel conditions. In one embodiment, an erasure-based approach is used to determine whether to incrementally increase or incrementally decrease a margin parameter in the outer-loop algorithm. Once one margin parameter is altered, other margin parameters can be adjusted accordingly.

Claims

1. In a wireless communication system, an apparatus for transmitting a packet in a transmission format, comprising:

a receiving subsystem for receiving channel quality information from a remote station;

a scheduling element for inserting a data payload into a packet for transmission, wherein the scheduling element is configured to use a outer-loop algorithm to determine the feasibility of a transmission format for the packet and to alter the parameters of the outer-loop algorithm in accordance with the channel quality information, and wherein the scheduling element is further configured to determine the parameters from a channel variation rate derived from a fading curve reconstructed from the channel quality information; and

a transmission subsystem for transmitting the packet to the remote station.

2. The apparatus of claim 1, wherein the channel quality information is Carder-to-Interference (C/I) values.

3. The apparatus of claim 2, wherein the scheduling element is further configured to reconstruct the fading curve using the C/I values.

4. The apparatus of claim 1, wherein the channel quality information is the channel variation rate sent from the remote station.

5. In a wireless communication system, an apparatus for transmitting a packet in a transmission format, comprising:

a receiving subsystem for receiving channel quality information from a remote station, wherein the channel quality information is Carrier-to-Interference (C/I) values;

a scheduling element for inserting a data payload into a packet for transmission, wherein the scheduling element is configured to use a outer-loop algorithm to determine the feasibility of a transmission format for the packet and to alter the parameters of the outer-loop algorithm in accordance with the channel quality information, wherein the scheduling element is further configured to reconstruct a fading curve using the C/I values, and wherein the scheduling element is further configured to determine a channel variation rate (CVR) using the fading curve; and

a transmission subsystem for transmitting the packet to the remote station.

6. The apparatus of claim 5, wherein the parameters of the outer-loop algorithm are altered in accordance with the CVR.

7. In a wireless communication system, a method for adapting a margin parameter of an outer-loop algorithm used to schedule packet transmissions, comprising:

receiving channel quality information from a remote station;

determining a channel variation rate from the channel quality information;

determining whether to increase or decrease the margin parameter by a margin increment,

wherein the margin increment is based on the channel variation rate and the channel variation rate derived from a fading curve reconstructed from the channel quality information;

comparing the margin parameter to a second margin parameter; and

altering the second margin parameter according to a set of selection rules.

8. The method of claim 7, wherein the channel quality information is carrier-to-interference (C/I) values.

9. The method of claim 8, wherein the margin increment is additionally determined by a packet error rate.

10. In a wireless communication system, a method for adapting a margin parameter of an outer-loop algorithm used to schedule packet transmissions, comprising:

receiving channel quality information from a remote station;

determining a channel variation rate from the channel quality information, wherein the channel quality information is carrier-to-interference (C/I) values;

determining whether to increase or decrease the margin parameter by a margin increment, including;

receiving a type of acknowledgment message from the remote station;

if the type of acknowledgment message is an acknowledgment, then decreasing the margin parameter by the margin increment; and

if the type of acknowledgment message is a negative acknowledgment, then increasing the margin parameter by the margin increment;

comparing the margin parameter to a second margin parameter; and

altering the second margin parameter according to a set of selection rules.

11. The method of claim 10, wherein margin increment for decreasing the margin parameter is determined by the formula:

Step_decrease =Step_increase/[1/(packet error rate)−

1],

wherein Step_increase is based on a channel variation rate and “

packet error rate”

is a system parameter.

12. The method of claim 10, wherein the margin increment for decreasing the margin parameter is adaptively sized based on a recent history of increases and decrease to the margin parameter.

13. The method of claim 12, wherein the margin increment for decreasing the margin parameter is adaptively sized based on an exponentially decreasing curve.

14. An apparatus for formatting a packet into a transmission format, comprising:

a memory element; and

a processing element configured to execute a set of instructions on the memory element, the set of instructions for;

determining fading curve representative of a transmission channel on which the packet is to be sent to a remote station;

determining a margin offset to the fading curve based on a feedback message from the remote station, the feedback message including one of a channel variation rate determined by the remote station or Carrier-to-Interference (C/I) values; and

determining whether a transmission format incorporating the margin offset is feasible for formatting the packet.

15. The apparatus of claim 14, wherein the processor is further configured to determine a power requirement for the transmission format incorporating the margin offset.

16. The apparatus of claim 15, wherein the processor is further configured to determine the margin offset to the fading curve based on a velocity of the remote station.

17. The apparatus of claim 14, wherein the processor is further configured to determine the margin offset based on whether the margin offset is to be increased or decreased.

18. An apparatus for formatting a packet into a transmission format, comprising:

a memory element; and

a processing element configured to execute a set of instructions on the memory element, the set of instructions for;

determining a fading curve representative of a transmission channel on which the packet is to be sent to a remote station;

determining a margin offset to the fading curve based on a feedback message from the remote station;

determining whether a transmission format incorporating the margin offset is feasible for formatting the packet;

determining a power requirement for the transmission format incorporating the margin offset; and

determining the margin offset to the fading curve based on a velocity of the remote station, wherein the velocity is determined using Doppler estimation.

19. An apparatus for formatting a packet into a transmission format, comprising:

a memory element; and

a processing element configured to execute a set of instructions on the memory element, the set of instructions for;

determining a fading curve representative of a transmission channel on which the packet is to be sent to a remote station;

determining a margin offset to the fading curve based on a feedback message from the remote station;

determining the margin offset based on whether the margin offset is to be increased or decreased, and determining a decreasing margin offset according to;

Step_decrease =Step_increase/[1/(packet error rate)−

1],

wherein Step_increase is the increasing margin offset and “

packet error rate”

is a system parameter; and

determining whether a transmission format incorporating the margin offset is feasible for formatting the packet.

20. A method for formatting a packet into a transmission format, comprising:

determining a fading curve representative of a transmission channel on which the packet is to be sent to a remote station;

determining a margin offset to the fading curve based on a feedback message from the remote station, the feedback message including one of a channel variation rate determined by the remote station or Carrier-to-Interference (C/I) values; and

determining whether a transmission format incorporating the margin offset is feasible for formatting the packet; and

if feasible, then formatting the packet according the transmission format incorporating the margin offset.

21. The method of claim 20, further comprising determining a power requirement for the transmission format incorporating the margin offset.

22. The method of claim 20, further comprising determining the margin offset to the fading curve based on a velocity of the remote station.

23. The method of claim 22, further comprising determining the margin offset based on whether the margin offset is to be increased or decreased.

24. A method for formatting a packet into a transmission format, comprising:

determining a fading curve representative of a transmission channel on which the packet is to be sent to a remote station;

determining a margin offset to the fading curve based on a feedback message from the remote station and based on a velocity of the remote station;

determining the margin offset based on whether the margin offset is to be increased or decreased, and determining a decreasing margin offset according to;

Step_decrease =Step_increase/[1/(packet error rate)−

1],

wherein Step_increase is the increasing margin offset and “

packet error rate”

is a system parameter;

determining whether a transmission format incorporating the margin offset is feasible for formatting the packet; and

if feasible, then formatting the packet according the transmission format incorporating the margin offset.

25. The method of claim 24, wherein the feedback message is a carrier-to-interference (C/I) values.