Method and system for simulation multimedia packet loss and jitter
View Patent ↗A Packet Loss and Jitter Simulator processes RTP packets coming through the MTA. Based on user input commands, the simulator drops or delays insertion of packets into the DSP portion of the MTA. Various modes that may be programmed include, but are not limited to, manual packet loss, fixed packet loss, random packet loss, manual jitter, fixed jitter, shift jitter, burst jitter, random jitter, and rolling jitter. All of these modes can be modified to simulate many real world conditions. The simulator typically operates on downstream packets, but can be used to provide similar functionality in the upstream direction.
1. A method for simulating impaired packet conditions in a packet flow having a flow rate, the method comprising:
receiving a first packet of the packet flow into a queue;
receiving a second packet of the packet flow into the queue, the first packet directly preceding the second packet, wherein timing of reception of the first packet and the second packet is related to the flow rate;
calculating a delay amount (DEL INST ) to retain the second packet in the queue based on an impairment condition command and based on a current delay variable (DEL CUR ), wherein the current delay variable (DEL CUR ) is determined based at least upon values of DEL CUR and DEL INST for the first packet; and
releasing the second packet from the queue after the calculated delay amount (DEL INST ) has elapsed in reference to the releasing of the first packet from the queue;
wherein the current delay variable is set equal to the delay amount if the current delay variable is less than a time related to the flow rate of the packet flow.
2. The method of claim 1 further comprising determining a modification to a second device that receives the packet flow over a network from a first device, the modification reducing effects on the second device responsive to network conditions causing an impairment of packet flow that is similar to conditions simulated according to the current delay variable.
3. A method for simulating impaired packet conditions in a packet flow having a flow rate, the method comprising:
receiving a first packet of the packet flow into a queue;
receiving a second packet of the packet flow into the queue, the first packet directly preceding the second packet, wherein timing of reception of the first packet and the second packet is related to the flow rate;
calculating a delay amount (DEL INST ) to retain the second packet in the queue based on an impairment condition command and based on a current delay variable (DEL CUR ), wherein the current delay variable (DEL CUR ) is determined based at least upon values of DEL CUR and DEL INST for the first packet;
releasing the second packet from the queue after the calculated delay amount (DEL INST ) has elapsed in reference to the releasing of the first packet from the queue;
wherein the current delay variable is set based on a normalized delay for a previously delayed packet in the packet flow; and
wherein the normalized delay is based at least on a difference between a calculated value of the current delay variable for the first packet and a time related to the flow rate.
4. The method of claim 3 wherein the current delay variable is set to a calculated value of the current delay variable that was applied to the first packet in the packet flow plus the delay amount to be added to the second packet minus a time related to the flow rate.
5. A method for simulating impaired packet conditions in a packet flow from a first device to a second device over a network, the method comprising:
receiving a first packet from the first device;
receiving a second packet from the first device, the second packet directly following the first packet in the packet flow, wherein timing of reception of the first packet and the second packet is related to a flow rate of the packet flow;
calculating a delay amount (DEL INST ) to apply to the second packet based on an impairment condition command and based on a current delay variable (DEL CUR ), wherein the current delay variable is determined based on a value of the delay amount (DEL INST ) corresponding to the first packet of the packet flow; and
processing the second packet according to the impairment condition command;
wherein the current delay variable is set to the delay amount if the current delay variable is less than a time related to the flow rate of the packet flow.
6. The method of claim 5 wherein the impairment condition command is to drop the second packet from the packet flow.
7. The method of claim 5 wherein the impairment condition command is to delay delivery of the second packet.
8. The method of claim 7 wherein the current delay variable is set based on a normalized delay for a previously delayed packet in the packet flow.
9. The method of claim 8 wherein the normalized delay is based at least on a difference between a calculated value of the current delay variable for the first packet and a time related to the flow rate.
10. The method of claim 8 wherein the current delay variable is set to a calculated value of the current delay variable that was applied to the first packet in the packet flow plus the delay amount to be added to the second packet minus a time related to the flow rate.
11. The method of claim 5 further comprising determining a modification to the second device that reduces effects thereto responsive to network conditions causing an impairment of packet flow that is similar to conditions simulated according to the current delay variable.