System and method for rate shifting for wireless VoIP

• US 7,944,889 B2
• Filed: 02/10/2006
• Issued: 05/17/2011
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Shetty, Sandeep, Qian, Lu
• Primary Examiner(s): Pérez-Gutiérrez; Rafael
• Assistant Examiner(s): Batista; Marcos
• Application Number:
  US11/351,369
• Publication Number:
  US 20070189225A1
• Time in Patent Office: 1,922 Days
• Field of Search: 370/332, 370/329
• US Class Current: 370/332
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0018 based on latency requirement
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 65/80 Responding to QoS
• 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 8/04 Registration at HLR or HSS [Home Subscriber Server]

Abstract

A method of rate shifting specially suited for the voice traffic, which differentiates poor channel conditions from a heavily loaded channel of a WLAN and adapts to the network traffic condition and channel condition promptly with low rate of false shifting. Determining when to rate shift is based on a combination of the received signal strength indication and the retry rate.

Claims

1. A method of rate shifting a data rate for a wireless transceiver, comprising:

operating the network at an original rate;

acquiring data representative of a current retry rate as a measure of network load of the network operating at the original rate;

acquiring data representative of a current received signal strength indication as a measure of a network channel condition of the network operating at the original rate;

determining whether performance of the network channel has degraded based on the data representative of the current retry rate;

responsive to determining that the performance of the network channel has degraded based on the data representative of the current retry rate, selectively determining whether signal quality of the network channel has degraded based on the data representative of the current received signal strength indication;

shifting, during a predetermined transition period, the operating of the network from the original rate to a second rate responsive to;

i) determining the performance of the network channel has degraded and ii) determining the signal quality of the network channel has degraded; and

maintaining, during the predetermined transition period, the operating of the network at the second rate.

2. A method for rate shifting according to claim 1, wherein the shifting includes shifting to a second rate lower than the original rate responsive to determining one of group consisting of a combination of current received signal strength indication is lower than a first predetermined level and the current retry rate is greater than a second predetermined level, and the current retry rate is greater than a third predetermined level.

3. A method for rate shifting according to claim 1, wherein the shifting includes shifting to a second rate higher than the original rate responsive to determining one of group consisting of a combination of current received signal strength indication is higher than a first predetermined level and the current retry rate is lower than a second predetermined level, and the received signal strength indication is greater than a third predetermined level.

4. A method according to claim 1, further comprising:

acquiring data representative of an error rate at the second rate;

comparing the data representative of an error rate at the second rate to an error rate at the first rate; and

remaining operating the network at the second rate responsive to data representative of the error rate at the second rate is less than the error rate at the first level after the predetermined transition period.

5. A method according to claim 1, further comprising:

acquiring data representative of an error rate at the second rate;

comparing the data representative of an error rate at the second rate to an error rate at the first rate; and

shifting operating the network to the original rate responsive to the data representative of an error rate at the second rate is greater than the error rate at the first level after the predetermined transition period.

6. A method according to claim 1, further comprising:

calculating a current average retry rate based on data representative of a past retry rate and the current retry rate;

wherein the average retry rate is used for determining whether to rate shift to a second rate.

7. A method according to claim 1, further comprising:

calculating a current average received signal strength indication based on data representative of a past received signal strength indication and the current received signal strength indication;

wherein the current average received signal strength is used for determining whether to rate shift to a second rate.

8. A method according to claim 7, further comprising:

calculating a current average retry rate based on data representative of a past retry rate and the current retry rate;

wherein the current average retry rate is used for determining whether to rate shift to the second rate.

9. A method according to claim 8, further comprising

wherein the calculating a current average retry rate uses the sum of 15/16 times the past retry rate and 1/16 times the current retry rate;

and

wherein the calculating an average received signal strength indication uses the sum of 15/16 times the past received signal strength indication and 1/16 times the current received signal strength indication.

10. A method according to claim 1, further comprising:

calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high received signal strength indication threshold;

calculating a current average received signal strength threshold;

dynamically adjusting one of group consisting of calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high received signal strength indication threshold based on the average received signal strength threshold.

11. A method according to claim 1, further comprising

calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and a high received signal strength indication threshold;

calculating a current average retry rate;

dynamically adjusting one of group consisting of calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high a received signal strength indication threshold based on the current average retry rate.

12. An apparatus configured for use in an associated network, the apparatus comprising:

circuitry for processing wireless signals; and

rate shifting logic coupled to the circuitry for processing wireless signals and operative to control the circuitry for processing wireless signals;

wherein the circuitry for processing signals is operating at an original rate;

wherein the rate shifting logic is operable to acquiring data representative of a current retry rate as a measure of network load from the circuitry for processing wireless signals;

wherein the rate shifting logic is operable to acquiring data representative of a current received signal strength indication as a measure of a network channel condition from the circuitry for processing wireless signals;

wherein the rate shifting logic is operable to determine whether performance of the network channel has degraded based on the data representative of the current retry rate;

wherein the rate shifting logic is operable, responsive to determining that the performance of the network channel has degraded based on the data representative of the current retry rate, to determine whether signal quality of the network channel has degraded based on the data representative of the current received signal strength indication;

wherein the rate shifting logic is operable, during a predetermined transition period, to shift the operating of the network from the original rate to a second rate responsive to;

i) determining the performance of the network channel has degraded and ii) determining the signal quality of the network channel has degraded; and

wherein the rate shifting logic is operable to cause the circuitry for processing wireless signals to operate at the second rate for the predetermined transition period.

13. An apparatus according to claim 12, wherein the rate shifting logic is operable to shift to a second rate lower than the original rate responsive to the rate shifting logic determining one of group consisting of a combination of current received signal strength indication is lower than a first predetermined level and the current retry rate is greater than a second predetermined level, and current retry rate is greater than a third predetermined level.

14. An apparatus according to claim 12, wherein the rate shifting logic is operable to shift to a second rate higher than the original rate responsive to the rate shifting logic determining one of group consisting of a combination of current received signal strength indication is higher than a first predetermined level and the current retry rate is lower than a second predetermined level, and the received signal strength indication is greater than a third predetermined level.

15. An apparatus according to claim 12, further comprising:

wherein the rate shifting logic is responsive to acquiring data representative of an error rate at the second rate to determine whether the error rate is acceptable; and

wherein the rate shifting logic is responsive to determining the error rate is acceptable to continue operating at the second rate.

16. An apparatus according to claim 12, further comprising:

wherein the rate shifting logic is operable to calculating a current average retry rate based on data representative of a past retry rate and the current retry rate acquired from the circuitry for processing wireless signals;

wherein the rate shifting logic is operable to calculating a current average received signal strength indication based on data representative of a past received signal strength indication and the current received signal strength indication; and

wherein the rate shifting logic uses the current average received signal strength and the current average retry rate for determining whether to rate shift to a second rate.

17. An apparatus according to claim 12, further comprising:

wherein the rate shifting logic is operable to calculate a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high received signal strength indication threshold;

wherein the rate shifting logic is operable to calculating a current average received signal strength threshold based on data acquired from the circuitry for processing wireless signals; and

wherein the rate shifting logic dynamically adjusts one of group consisting of calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high received signal strength indication threshold based on the average received signal strength threshold.

18. An apparatus according to claim 12, further comprising

wherein the rate shifting logic is operable to calculate a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and a high received signal strength indication threshold;

wherein the rate shifting logic is operable to calculate a current average retry rate based on data acquired from the circuitry for processing wireless signals; and

wherein the rate shifting logic dynamically adjusts one of group consisting of calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high a received signal strength indication threshold based on the current average retry rate.

19. An apparatus adapted for use with an associated network, the apparatus comprising:

means for processing wireless signals of the associated network operating at an original rate; and

means for acquiring data representative of a current retry rate as a measure of network load;

means for acquiring data representative of a current received signal strength indication as a measure of a network channel condition;

means for determining whether performance of the network channel has degraded based on the data representative of the current retry rate;

means responsive to determining that the performance of the network channel has degraded based on the data representative of the current retry rate, for selectively determining whether signal quality of the network channel has degraded based on the data representative of the current received signal strength indication; and

means for shifting, during a predetermined transition period, the operating of the associated network from the original rate to a second rate responsive to;

i) determining performance of the channel has degraded and ii) determining the signal quality of the network channel has degraded; and

means for maintaining the second rate for the predetermined transition period.

20. An apparatus according to claim 19, further comprising:

means for acquiring data representative of an error rate at the second rate;

means for comparing the data representative of an error rate at the second rate to an error rate at the first rate;

means for determining whether to remain at the second rate responsive to whether the data representative of the error rate at the second rate is less than the error rate at the first rate.

21. An apparatus according to claim 19, further comprising:

means for calculating a current average retry rate based on data representative of a past retry rate and the current retry rate;

means for calculating a current average received signal strength indication based on data representative of a past received signal strength indication and the current received signal strength indication;

wherein the means for controlling determines whether to shift to a second rate based on the current average retry rate and the current average received signal strength indication.

22. An apparatus according to claim 19, further comprising:

means for calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high received signal strength indication threshold;

means for calculating a current average received signal strength threshold;

means for calculating a current average retry rate;

means for dynamically adjusting one of group consisting of calculating a minimum retry threshold, a maximum retry threshold, a low received signal strength indication threshold and high received signal strength indication threshold based on the average received signal strength threshold responsive to one of a group consisting of the means for calculating the current average retry rate and the means for calculating the current average received signal strength indication.