Quality guarantee for real-time applications over shared networks
View Patent ↗A shared wireless channel may serve real-time traffic and non-real-time traffic. Depending on channel conditions, the real-time traffic may experience variable levels of quality. The present invention contemplates systems and methods for guaranteeing bounded access time for real-time applications in a shared wireless network in the presence of non-real-time traffic. The systems and methods provide mechanisms to adapt to changing characteristics of wireless channels and to maximize throughput of non-real-time traffic while preserving the quality of real-time applications. The systems and methods may be extended generally to provide adaptive control over the delivery of multiple classes of traffic to protect the quality of critical applications over a shared transmission medium, including IEEE 802.11 networks, IEEE 802.16 networks, and DOCSIS networks.
1. A method comprising:
measuring, by an access point, the performance of a shared wireless channel by making direct measurements of: (a) a number of packets of both critical traffic and non-critical traffic transmitted during a time period, (b) transmission metrics associated with the transmission of those packets during the time period, and (c) a number of packets of critical traffic that experienced a transmission delay exceeding a predetermined amount of time during the time period, these direct measurements being made in order to estimate a residual bandwidth for a subsequent time period, wherein said residual bandwidth is in terms of a number of critical transmissions possible for the subsequent time period; and
adjusting, by the access point, control parameters for transmission of critical traffic and non-critical traffic for the subsequent time period based on each of the direct measurements (a)-(c) so as to maintain a quality of service for critical traffic generated by critical applications and to optimize utilization of any residual bandwidth.
2. A method according to claim 1 , wherein the shared wireless channel uses a protocol compliant with one of IEEE 802.11a (1999) standard, IEEE 802.11b (1999) standard, IEEE 802.11c (2001) standard, IEEE 802.11d (2001) standard, IEEE 802. 11e (2005) standard, IEEE 802.11g (2003) standard, IEEE 802.11h (2004) standard, IEEE 802. 11i (2004) standard, and IEEE 802.11j (2004) standard.
3. A method according to claim 1 , further comprising determining the residual bandwidth for the subsequent time period based on direct measurements of a number of packets of the critical traffic, including probe packets not generated by critical applications, transmitted during the time period.
4. A method according to claim 1 , wherein the non-critical traffic includes packets generated by critical applications but transmitted with a lower associated quality of service than for the critical traffic.
5. A method according to claim 1 , wherein the transmission metrics include one or more of delay metrics, loss metrics, and queue occupancy.
6. A method according to claim 1 , wherein adjusting control parameters for transmission of critical traffic and non-critical traffic involves allocating a portion of available bandwidth each to critical applications and to non-critical applications in order to balance traffic based on a measure of fairness or a predetermined allocation.
7. A method according to claim 1 , wherein adjusting control parameters for transmission of critical traffic includes allowing a new critical application to transmit critical packets if its bandwidth requirement is less than or equal to the residual bandwidth for the subsequent time period.
8. A method according to claim 1 , wherein adjusting control parameters for non-critical traffic includes adjusting the number of non-critical packets allowed to be sent during the subsequent time period.
9. A method according to claim 3 wherein adjusting control parameters for transmission of critical traffic includes adjusting the number of probe packets to be sent during the subsequent time period.
10. A method comprising:
measuring, by an access point, the performance of a shared transmission medium by making direct measurements of: (a) a number of packets of both critical and non-critical traffic transmitted during a time period, (b) transmission metrics associated with the transmission of those packets during the time period, and (c) a number of packets of critical traffic that experienced a transmission delay exceeding a predetermined amount of time during the time period, these direct measurements being made in order to estimate residual bandwidth for a subsequent time period, wherein said residual bandwidth is in terms of a number of critical transmissions possible for the subsequent time period; and
adjusting, by the access point, control parameters for transmission of critical traffic and non-critical traffic for the subsequent time period based on each of the direct measurements (a)-(c) so as to maintain a quality of service for critical traffic generated by critical applications and to optimize utilization of any residual bandwidth;
wherein the number of packets of critical traffic transmitted during the time period includes probe packets not generated by critical applications.
11. A method according to claim 10 , wherein the shared transmission medium is either wireless or wired and uses a protocol compliant with one of IEEE 802.11a (1999) standard, IEEE 802.11b (1999) standard, IEEE 802.11c (2001) standard, IEEE 802.11d (2001) standard, IEEE 802,11e (2005) standard, IEEE 802.11g (2003) standard, IEEE 802.11h (2004) standard, IEEE 802.11i (2004) standard, IEEE 802.11j (2004) standard, IEEE 802.16 networks, and DOCSIS networks.
12. A method according to claim 10 , wherein the non-critical traffic includes packets generated by critical applications but transmitted with a lower associated quality of service than for the critical traffic.
13. A method according to claim 10 , wherein the transmission metrics include one or more of delay metrics, loss metrics, and queue occupancy.
14. A method according to claim 10 , wherein adjusting control parameters for transmission of critical traffic and non-critical traffic involves allocating a portion of available bandwidth each to critical applications and to non-critical applications in order to balance traffic based on a measure of fairness or a predetermined allocation.
15. A method according to claim 10 , wherein adjusting control parameters for transmission of critical traffic includes allowing a new critical application to transmit critical packets if its bandwidth requirement is less than or equal to the residual bandwidth for the subsequent time period.
16. A method according to claim 10 , wherein adjusting control parameters for non-critical traffic includes adjusting the number of non-critical packets allowed to be sent during the subsequent time period.
17. A method according to claim 10 , wherein adjusting control parameters for transmission of critical traffic includes adjusting the number of probe packets to be sent during the subsequent time period.
18. A system comprising:
a control module operative to control transmission of critical traffic and non-critical traffic over a shared wireless channel;
a media access control module operative to transmit packets of critical traffic and non-critical traffic over the shared wireless channel; and
an update module operative to:
make direct measurements of the number of packets of both critical traffic and non-critical traffic transmitted during a time period;
make direct measurements of transmission metrics associated with transmission of the packets during the time period;
make direct measurements of a number of packets of critical traffic that experienced a transmission delay exceeding a predetermined amount of time during the time period;
estimate residual bandwidth available over the shared transmission medium for a subsequent time period based on each of the direct measurements, wherein said residual bandwidth is in terms of a number of critical transmissions possible for the subsequent time period; and
adjust control parameters to be used by the control module to control transmission of critical traffic and non-critical traffic during the subsequent time period so as to maintain a quality of service for critical traffic generated by critical applications and to optimize utilization of any residual bandwidth.
19. A system according to claim 18 , wherein the shared wireless channel uses a protocol compliant with one of IEEE 802.11a (1999) standard, IEEE 802.11b (1999) standard, IEEE 802.11c (2001) standard, IEEE, 802.11d (2001) standard, IEEE 802. 11e (2005) standard, IEEE 802.11g (2003) standard, IEEE 802.11h (2004) standard, IEEE 802.11i (2004) standard, and IEEE 802.11j (2004) standard.
20. A system according to claim 18 , wherein the critical traffic includes probe packets not generated by critical applications.
21. A system according to claim 18 , wherein the non-critical traffic includes packets generated by critical applications but transmitted with a lower associated quality of service than for critical traffic.
22. A system according to claim 18 , wherein the transmission metrics include one or more of delay metrics, loss metrics, and queue occupancy.
23. A system according to claim 18 , wherein the update module is operative to adjust control parameters for transmission of critical traffic and non-critical traffic by allocating a portion of available bandwidth each to critical applications and to non-critical applications in order to balance traffic based on a measure of fairness or a predetermined allocation.
24. A system according to claim 18 , wherein the update module is operative to adjust control parameters for transmission of critical traffic by allowing a new critical application to transmit critical packets if its bandwidth requirement is less than or equal to the residual bandwidth for the subsequent time period.
25. A system according to claim 18 , wherein the update module is operative to adjust control parameters for non-critical traffic by adjusting a number of non-critical packets allowed to be sent during the subsequent time period.
26. A system according to claim 20 , wherein the update module is operative to adjust control parameters for transmission of critical traffic by adjusting the number of probe packets to be sent during the subsequent time period.
27. A system according to claim 20 , further comprising a probe generator operative to generate probe packets.