System and method for selecting the size of dynamic voice jitter buffer for use in a packet switched communications system

• US 20050047396A1
• Filed: 08/29/2003
• Published: 03/03/2005
• Est. Priority Date: 08/29/2003
• Status: Abandoned Application

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Frandsen, Svend, Helm, David P.
• Application Number:
  US10/651,520
• Publication Number:
  US 20050047396A1
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/115 using a dedicated packet
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9023 for implementing a jitter-buffer
• CPC Class Codes: H04L 49/9078 using an external memory or storage device

Abstract

A packet switched communications system (100) for use with a dynamic voice jitter buffer (203) and voice over Internet protocol (VoIP) packets includes a source (101) transmitting at least one VoIP packet, one or more routers (105, 107, 109) for routing the VoIP packets and a destination (111) for receiving the at least one VoIP packet. The VoIP packet operates to convey congestion information regarding the packet switched communications system (100) to at least one buffer located at the destination to dynamically control the capacity of the jitter buffer located at the destination to provide VoIP communication with no jitter and minimal delay.

Claims

1. A packet switched communications system having a dynamic voice jitter buffer for use with voice over Internet protocol (VoIP) packets comprising:

a source transmitting at least one VoIP packet;

at least one router for routing the VoIP packet to a specified destination;

a destination for receiving the at least one VoIP packet; and

wherein the VoIP packet operates to convey congestion information regarding the packet switched communications system to at least one buffer located at the destination.

2. A packet switched communications system as in claim 1, wherein the VoIP packet conveys congestion information comprising the steps of:

setting the time-to-live (TTL) field in the VoIP packet to a predetermined value;

decrementing the TTL value by one count as it traverses each respective router in the packet switched communications system;

calculating the number of routers the VoIP packet has passed through based on a final TTL value determined at the destination; and

adjusting the capacity of the at least one buffer at the destination based on the final TTL value in order to mitigate non-periodic receipt of incoming VoIP packets at the destination.

3. A packet switched communications system as in claim 2, further including the step of:

selecting a first, second or third capacity of the at least one buffer based upon the final TTL value.

4. A packet switched communications system as in claim 1, wherein the VoIP packet conveys congestion information comprising the steps of:

determining the speed upon which the VoIP packet has been received at the at least one router;

setting at least one field in the VoIP packet to indicate if the packet has traversed at least one previous router below a predetermined speed; and

adjusting the capacity of at least one buffer at the destination based upon recognition of the at least one field in order to mitigate non-periodic receipt of incoming VoIP packets at the destination.

5. A packet switched communications system as in claim 4, further including the step of:

setting the least one field within the VoIP packet with a congestion value based upon the speed of the originating link.

6. A packet switch communications systems claim 4, further including the step of:

setting the least one field within the VoIP packet with a congestion value based upon the speed of the destination link.

7. A packet switched communications system as in claim 1, further including the step of:

selecting a first, second or third capacity of the at least one congestion value.

8. A packet switched communications system as in claim 1, wherein the VoIP packet conveys congestion information comprising the steps of:

determining at the at least one router if a received packet has encountered at least one congested router;

setting at least one field in the VoIP packet indicating if the communications speed of a destination link is below a predetermined threshold; and

adjusting the capacity of at least one buffer at the destination based upon recognition of the at least one field in order to mitigate non-periodic receipt of incoming VoIP packets at the destination.

9. A packet switched communications system as in claim 8, further comprising the step of:

selecting a first, second or third capacity of the at least one buffer based upon a value set within the at least one field.

10. A method for adjusting the size of a jitter buffer for use in a voice over Internet protocol (VoIP) packet switched communications system comprising the steps of:

adjusting the time-to-live (TTL) field in a VoIP packet to a predetermined value at a source;

decrementing the TTL field by at least one count each time the VoIP packet traverse a router in the VoIP packet system;

reading the TTL field at a destination; and

adjusting the size of a jitter buffer based upon the TTL value in order to mitigate the effect of receipt of non-period VoIP packets at the destination.

11. A method for adjusting the size of a jitter buffer, as in claim 10:

wherein the jitter buffer is located at the destination.

12. A method for adjusting the size of a jitter buffer, as in claim 10 further includes the steps of:

comparing the predetermined value of the TTL field with the value read at the destination to produce a compared value; and

mapping the compared value to a predetermined jitter buffer capacity to provide a substantially continuous flow of VoIP packets from jitter buffer.

13. A method for adjusting the size of a jitter buffer as in claim 12, further comprising the step of:

setting the capacity of the jitter buffer to either a first, second or third predetermined capacity based upon the compared value.

14. A method for adjusting the size of a jitter buffer for use with a packet network transmitting voice over Internet protocol (VoIP) packets based upon transmission path delay comprising the steps of:

determining the amount of transmission delay through a transmission path that a VoIP packet has encountered upon receipt by at least one router in the packet network;

setting a field within the VoIP packet when the transmission rate for a link used for the VoiP is below a predetermined threshold;

recognizing the field at a destination of the VoIP packet; and

adjusting the size of a jitter buffer based upon recognition of the field in order to mitigate the effect of receipt of non-periodic VoiP packets at the destination.

15. A method for adjusting the size of a jitter buffer as in claim 14, wherein the jitter buffer is located at the destination.

16. A method for adjusting the size of a jitter buffer as in claim 14, further including the steps of:

setting the field using a numeric value based upon the amount of transmission path delay; and

mapping the numeric value into a minimal jitter buffer size required for that amount of delay.

17. A method for adjusting the size of a jitter buffer as in claim 14, further comprising the step of:

adjusting the size of the jitter buffer to either a first, second or third capacity based upon the numeric value set within the field.

18. A method for adjusting the size of a jitter buffer for use with a packet network transmitting voice over Internet protocol (VoIP) packets based upon transmission path delay comprising the steps of:

determining the amount of transmission delay through a transmission path that a VoIP packet has encountered upon receipt by at least one router in the packet network;

setting a field within the VoIP packet when the congestion of the link exceeds a predetermined threshold;

recognizing the field at a destination of the VoIP packet; and

adjusting the size of a jitter buffer based upon recognition of the field in order to mitigate the effect of receipt of non-periodic VoiP packets at the destination.

19. A method for adjusting the size of a jitter buffer as in claim 18, wherein the jitter buffer is located at the destination.

20. A method for adjusting the size of a jitter buffer as in claim 18, further including the steps of:

setting the field using a numeric value based upon the link congestion; and

mapping the numeric value into a minimal jitter buffer size required for that amount of delay.

21. A method for adjusting the size of a jitter buffer as in claim 18, further comprising the step of:

adjusting the size of the jitter buffer to either a first, second or third capacity based upon the numeric value set within the field.