Traffic management in a wireless data network
View Patent ↗In a radio access network (e.g., a cellular network), a radio node is configured to monitor one or more characteristics of a stream of data packets destined for an access terminal (e.g., a cellular telephone, laptop computer, etc.) to determine whether there is congestion in a network supplying the stream of data packets. If the radio node detects congestion, the radio node transmits a congestion alert to another device to cause the rate at which data enters the network to be slowed. The rate may be slowed either directly (e.g., by an upstream device which slows the rate at which the upstream device supplies the data to the network) or indirectly (e.g., by a downstream device which requests a slower delivery of data from the radio node).
1. A method for reducing congestion in a radio access network, the method comprising:
monitoring, at a radio node, congestion in a stream of data packets that is received at the radio node from a radio network controller over a network and that is to be sent over an air link to one or more access terminals, wherein monitoring the congestion comprises:
monitoring numbers of the stream of data packets for a gap in sequential
numbering associated with the stream of data packets; and
monitoring a one way delay in the stream of data packets; and
reducing a rate at which the stream of data packets is sent by the radio network controller over the network to the radio node in response to the monitoring, wherein reducing the rate at which the stream of data packets is sent over the network to the radio node comprises:
reducing a rate at which the radio network controller transmits data packets into the network, wherein reducing the rate at which the radio network controller transmits the data packets into the network comprises:
using a leaky bucket mechanism to reduce the rate at which the data packets enter the network, wherein using the leaky bucket mechanism comprises:
incrementing a counter at a rate of R bytes per second;
decrementing the counter by an amount proportional to a size of a data packet that is transmitted to the network; and
preventing data packets from being transmitted to the network if the counter reaches zero.
2. The method of claim 1 wherein monitoring the congestion further comprises:
sending a congestion alert message to the radio network controller if at least one of the gap in the sequential numbering is detected by monitoring the numbers, or the current average of the one way delay exceeds a predetermined value; and
wherein reducing the rate in response to the monitoring further comprises:
reducing the rate in response to the congestion alert message.
3. The method of claim 1 wherein monitoring the congestion comprises determining how long it takes at least some data packets of the stream of data packets to travel over the network.
4. The method of claim 3 wherein determining how long it takes the at least some data packets comprises:
comparing a current time with an indicator included in a data packet of the at least some data packets; the indicator indicating an approximate time when the data packet entered the network.
5. The method of claim 1 further comprising:
marking data packets in the stream of data packets if congestion is detected.
6. The method of claim 5 wherein monitoring the congestion comprises:
determining how many received data packets of the stream of data packets over time are marked data packets.
7. The method of claim 1 wherein reducing the rate at which the stream of data packets is sent over the network to the radio node comprises:
marking a data packet with information that signals an access terminal to reduce a rate at which the access terminal requests delivery of data over the air link.
8. The method of claim 1 wherein reducing the rate at which the stream of data packets is sent over the network to the radio node comprises:
replacing content of a data packet with random data, wherein receipt of the data packet with random data signals an access terminal to reduce a rate at which the access terminal requests delivery of data over the air link.
9. The method of claim 1 wherein reducing the rate at which the stream of data packets is sent over the network to the radio node comprises:
dropping packets destined for an access terminal prior to the packets entering the network and prior to the packets being associated with the sequential numbers.
10. A radio access network comprising:
a backhaul network;
a radio network controller configured to receive a stream of data packets destined for an access terminal and to transmit the stream of data packets to a radio node via the backhaul network; and
a radio node configured to receive the stream of data packets and transmit the stream of data packets to the access terminal via an air link, wherein the radio node is configured to monitor congestion in the stream of data packets, wherein monitoring the congestion comprises monitoring numbers of the stream of data packets for a gap in sequential numbering associated with the stream of data packets and monitoring a one way delay in the stream of data packets;
wherein the radio access network is configured to:
cause a reduction in a rate at which the stream of data packets enters the backhaul network in response to monitoring the congestion;
cause the reduction in the rate at which the stream of data packets enters the backhaul network by reducing the rate at which the radio network controller transmits data packets into the backhaul network;
wherein the radio network controller comprises a leaky bucket mechanism which is configured to control the rate at which the stream of data packets enters the backhaul network,
wherein the leaky bucket mechanism is configured to increment a counter at a rate of R bytes per second, to decrement the counter by an amount proportional to a size of a data packet that is transmitted to the network, and to prevent data packets from being transmitted to the network if the counter reaches zero.
11. The radio access network of claim 10 wherein the radio network controller is configured to sequentially number each packet in the stream of data packets prior to the stream of data packets entering the backhaul network.
12. The radio access network of claim 11 wherein the radio network controller is configured to number each packet sequentially in accordance with Radio-Link Protocol.
13. The radio access network of claim 10 wherein monitoring the one way delay comprises using a sliding window of packet delay values to estimate a current average of the one-way delay.
14. The radio access network of claim 10 wherein the radio network controller is configured to determine how long it takes at least some data packets of the stream of data packets to travel over the backhaul network.
15. The radio access network of claim 14 wherein the radio node is configured to determine how long it takes the at least some data packets to travel over the backhaul network by comparing a current time with an indicator included in a data packet of the at least some data packets; the indicator indicating an approximate time when the data packet entered the backhaul network.
16. The radio access network of claim 15 wherein the radio access network is configured to cause the reduction in the rate at which the stream of data packets enters the backhaul network by dropping packets destined for an access terminal prior to the packets being sequentially numbered.
17. The radio access network of claim 10 wherein the backhaul network comprises a plurality of network devices at least some of which are configured to mark data packets in the stream of data packets if the network device detects congestion.
18. The radio access network of claim 17 wherein the radio node is configured to determine how many received data packets of the stream of data packets over time are marked data packets.
19. The radio access network of claim 10 wherein the radio access network is configured to cause the reduction in the rate at which the stream of data packets enters the backhaul network by marking a data packet with information that signals an access terminal to reduce a rate at which the access terminal requests delivery of data over the air link.
20. The radio access network of claim 10 wherein the radio access network is configured to cause the reduction in the rate at which the stream of data packets enters the backhaul network by replacing content of a data packet with random data, wherein receipt of the data packet with random data signals an access terminal to reduce a rate at which the access terminal requests delivery of data over the air link.
21. A method for reducing congestion in a radio access network, the method comprising:
monitoring congestion in a stream of data packets that is received at a radio node from a network and that is to be sent over an air link to one or more access terminals; and
reducing a rate at which the stream of data packets is sent over the network to the radio node in response to the monitoring;
wherein reducing the rate at which the stream of data packets is sent over the network to the radio node comprises replacing content of a data packet of the stream of data packets with random data, wherein receipt of the data packet with random data at an access terminal signals the access terminal to reduce a rate at which the access terminal requests delivery of data over the air link.
22. The method of claim 21 wherein monitoring the congestion further comprises:
sending a congestion alert message to the radio network controller if at least one of the gap in the sequential numbering is detected by monitoring the numbers, or the current average of the one way delay exceeds a predetermined value; and
wherein reducing the rate in response to the monitoring further comprises:
reducing the rate in response to the congestion alert message.
23. The method of claim 21 wherein monitoring the congestion comprises:
using a sliding window of packet delay values to estimate a current average of the one way delay.
24. The method of claim 21 wherein monitoring the congestion comprises determining how long it takes at least some data packets of the stream of data packets to travel over the network.
25. The method of claim 24 wherein determining how long it takes the at least some data packets comprises:
comparing a current time with an indicator included in a data packet of the at least some data packets; the indicator indicating an approximate time when the data packet entered the network.
26. The method of claim 21 further comprising:
marking data packets in the stream of data packets if congestion is detected.
27. The method of claim 26 wherein monitoring the congestion comprises:
determining how many received data packets of the stream of data packets over time are marked data packets.