Method and apparatus for a rate control in a high data rate communication system

• US 7,417,957 B2
• Filed: 03/24/2004
• Issued: 08/26/2008
• Est. Priority Date: 04/24/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Attar, Rashid A., Sindhushayana, Nagabhushana T., Esteves, Eduardo A. S.
• Primary Examiner(s): Moe; Aung S.
• Assistant Examiner(s): Rose; Kerri M
• Application Number:
  US10/808,939
• Publication Number:
  US 20040179499A1
• Time in Patent Office: 1,616 Days
• Field of Search: 370/230, 370/235, 370/252, 370/335, 370/338, 370/342, 455/226.3, 375/227
• US Class Current: 370/252
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0016 involving special memory structures, e.g. look-up tables
• CPC Class Codes: H04L 1/002 Algorithms with memory of the previous states, e.g. Markovian models
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A method and an apparatus for rate control in a high data rate (HDR) communication system are disclosed. An exemplary HDR communication system defines a set of data rates, at which an access point (AP) may send data packets to an access terminal (AT). The data rate is selected to maintain targeted packet error rate (PER). The AT'"'"'s open loop algorithm measures received signal to interference and noise ratio (SINR) at regular intervals, and uses the information to predict an average SINR over the next packet duration. The AT'"'"'s closed loop algorithm measures a packet error rate (PER) of the received signal, and uses the PER to calculate a closed loop correction factor. The loop correction factor is added to the SINR value predicted by the open loop, resulting in an adjusted SINR.

Claims

1. An apparatus for rate selection in wireless communications, comprising:

means for determining an open loop prediction of signal to noise and interference ratio;

means for determining a closed loop correction, comprising;

means for determining a quality of a received packet; and

means for decreasing the closed loop correction if the quality is bad; and

means for selecting a data rate in accordance with the open loop prediction and the closed loop correction,

wherein the means for decreasing the closed loop correction comprises means for computing an updated value of an outer loop correction in accordance with an equation;

L_new=max(L_oldδ

, L_min),

wherein L_new is the updated value of the outer loop correction, L_odd is a previous value of the outer loop correction, δ

is a step size, and L_min is the minimum value that the outer loop correction can attain.

2. The apparatus of claim 1, wherein the means for determining a closed loop correction further comprises:

means for determining a quality of a received packet; and

means for increasing the closed loop correction if the quality is good.

3. The apparatus of claim 2, wherein the means for increasing the closed loop correction comprises:

means for determining a mode of operation; and

means for increasing the closed loop correction in accordance with the mode of operation.

4. An apparatus for rate selection in wireless communications, comprising:

means for determining an open loop prediction of signal to noise and interference ratio;

means for determining a closed loop correction, comprising;

means for determining a quality of a received packet; and

means for increasing the closed loop correction if the quality is good, comprising;

means for determining a mode of operation, comprising;

means for determining a time fraction for which the packet is received; and

means for selecting the mode of operation in accordance with the time fraction; and

means for increasing the closed loop correction in accordance with the mode of operation; and

means for selecting a data rate in accordance with the open loop prediction and the closed loop correction.

5. The apparatus of claim 4, wherein the means for determining a time fraction comprises means for computing an updated value of the time fraction when the packet is detected in accordance with an equation:

AF_New=(1−

f)·

AF_Old+f

wherein AF_new is the updated value of the time fraction, AF_Old is a previous value of the time fraction, and f∈

(0,1) is a parameter controlling a rate of change of the time fraction.

6. The apparatus of claim 4, wherein the means for determining a time fraction comprises means for computing an updated value of the time fraction when the packet fails to be detected in accordance with an equation:

AF_New=(1−

f)·

AF_Old,

wherein AF_new is the updated value of the time fraction, AF_Old is a previous value of the time fraction, and f∈

(0,1) is a parameter controlling a rate of change of the time fraction.

7. The apparatus of claim 4, wherein the means for selecting the mode of operation comprises means for selecting a fast attack mode if all of the following conditions are satisfied:

L<

L_AMThreshold,

AF<

AF_Idle, and

the two most recently received packets are good,

wherein L_AMThreshold is a threshold controlling a transition to the fast attack mode with respect to L and AF_Idle is a threshold controlling a transition to the fast attack mode with respect to AF.

8. The apparatus of claim 7, wherein the means for increasing the closed loop correction in accordance with the mode of operation comprises means for computing an updated value of an outer loop correction in accordance with an equation:

L_new=min(L_old+δ

′

, L_max),

wherein L_new is the updated value of the outer loop correction, L_Old is a previous value of the outer loop correction, δ

′

is a step size, and L_max is the maximum value that the outer loop correction can attain.

9. The apparatus of claim 4, wherein the means for selecting the mode of operation comprises means for selecting a normal mode if any of the following conditions are satisfied:

L≧

L_NMThreshold,

AF≧

AF_Busy, or

the most recently received packet is bad,

wherein L_NMThreshold is a threshold controlling a transition to the normal mode with respect to L and AF_Busy is a threshold controlling a transition to the normal mode with respect to AF.

10. The apparatus of claim 9, wherein the means for increasing the closed loop correction in accordance with the mode of operation comprises means for computing an updated value of an outer loop correction in accordance with an equation:

L_new=min(L_old+TARGET_PER·

δ

, L_max),

wherein L_new is the updated value of the outer loop correction, L_old is a previous value of the outer loop correction, TARGET_PER is a packet error rate to be attained, δ

is a step size, and L_max is the maximum value that the outer loop correction can attain.

11. An apparatus for rate selection in wireless communications, comprising:

means for determining an open loop prediction of signal to noise and interference ratio;

means for determining a closed loop correction; and

means for selecting a data rate in accordance with the open loop prediction and the closed loop correction, comprising;

means for summing the open loop prediction of signal to noise and interference ratio and the closed loop correction; and

means for selecting the data rate as the highest data rate, a signal to noise ratio of which is below the summed signal to noise ratio.