METHOD AND APPARATUS TO INDICATE MAXIMUM SCHEDULING DELAY FOR JITTER BUFFER IMPLEMENTATIONS

• US 20080165766A1
• Filed: 12/10/2007
• Published: 07/10/2008
• Est. Priority Date: 01/09/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Synnergren, Per
• Granted Patent: US 8,111,720 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints

Abstract

In VoIP systems, there is a tradeoff between reducing number of lost packets and end-to-end delay when dealing with jitters. Increasing the jitter buffer space on a mobile wireless terminal reduces the likelihood of lost packets but increases the end-to-end delay. Decreasing the jitter buffer space shortens the end-to-end delay, but there is a greater likelihood of retransmissions and dropped packets. Optimum solution can be arrived at if the jitter buffer space on the mobile wireless terminal can be matched to the scheduling delay. This is difficult to achieve in conventional system because the scheduling delay introduced by the network is unknown to the mobile wireless terminal. Thus, constant adjustment is required. One way to overcome this problem is to apprise the mobile wireless terminal of the maximum scheduling delay.

Claims

1. A mobile wireless terminal capable of performing VoIP (Voice over Internet Protocol) over mobile broadband, comprising:

a jitter buffer configured to buffer the VoIP packets from a base station over a radio interface; and

a terminal controller operatively coupled to the jitter buffer and configured to allocate an amount of buffer space in the jitter buffer sufficient for a maximum scheduling delay in the jitter buffer in accordance with a maximum scheduling delay indication associated with the mobile wireless terminal, the maximum scheduling delay indication being received from the base station over the radio interface.

2. The mobile wireless terminal of claim 1, further comprising:

a radio unit configured to receive VoIP packets from a base station, wherein the radio unit functions as the radio interface; and

a decode unit operatively coupled to the jitter buffer and configured to decode the VoIP packets buffered in the jitter buffer,

wherein the terminal controller is operatively coupled to the radio unit and to the decode unit and is configured to control operations of the radio unit and the decode unit, and

wherein the decode unit is configured to start decoding the VoIP packets from the jitter buffer once the allocated buffer space is full for a first time after communication with the base station is established.

3. The mobile wireless terminal of claim 2,

wherein the maximum scheduling delay indication is received explicitly as one of an amount of time or an amount of data, and

wherein the terminal controller is configured to allocate the buffer space in the jitter buffer corresponding to the amount of time or the amount of data.

4. The mobile wireless terminal of claim 2, wherein the radio unit is configured to receive the maximum scheduling delay indication prior to receiving the VoIP packets.

5. The mobile wireless terminal of claim 2,

wherein the radio unit is configured to receive a predetermined packet from the base station, the predetermined packet including VoIP data,

wherein an amount of the VoIP data in the predetermined packet corresponds to the maximum scheduling delay, and

wherein the terminal controller is configured to allocate the buffer space in the jitter buffer corresponding to the amount of the VoIP data in the predetermined packet.

6. The mobile wireless terminal of claim 5,

wherein the radio unit is configured to:

receive one or more VoIP packets encapsulated in an initial burst packet from the base station, wherein the initial burst packet is received prior to receiving any other VoIP packets;

unencapsulate the initial burst packet into the one or more VoIP packets; and

provide the unencapsulated one or more VoIP packets to the jitter buffer, wherein the initial burst packet is the predetermined packet.

26. The mobile wireless terminal of claim 1, further comprising:

a radio unit configured to receive VoIP packets from a base station, wherein the radio unit functions as the radio interface; and

a decode unit operatively coupled to the jitter buffer and configured to decode the VoIP packets buffered in the jitter buffer,

wherein the terminal controller operatively is coupled to the radio unit and the decode unit and configured to control operations of the radio unit and the decode unit, and

wherein the decode unit is configured to start decoding the VoIP packets from the jitter buffer after a wait time passes since communication with the base station is established.

27. The mobile wireless terminal of claim 26, wherein the wait time corresponds to the maximum scheduling delay.

7. A method of reducing jitter for VoIP (Voice over Internet Protocol) over mobile broadband, comprising:

receiving, over a radio interface, a maximum scheduling delay indication from the base station, the maximum scheduling delay indication corresponding to a maximum scheduling delay associated with the mobile wireless terminal; and

allocating an amount of buffer space in a jitter buffer of the mobile wireless terminal sufficient for the maximum scheduling delay.

8. The method of claim 7, further comprising:

receiving VoIP packets from the base station and storing the VoIP packets in the jitter buffer;

determining whether the allocated buffer space is full; and

starting the VoIP decoding process when it is determined, for a first time after establishing communication with the base station, that the allocated buffer space is full.

9. The method of claim 8,

wherein the maximum scheduling delay indication is provided explicitly as one of an amount of time or an amount of data, and

wherein the act of allocating the amount of buffer space in the jitter buffer of the mobile wireless terminal comprises allocating the buffer space in the jitter buffer corresponding to the amount of time or the amount of data.

10. The method of claim 8, wherein the act of receiving the indication of the maximum scheduling delay indication occurs prior to the act of receiving the VoIP (Voice over Internet Protocol) packets.

11. The method of claim 8,

wherein the act of receiving the VoIP (Voice over Internet Protocol) packets from the base station comprises receiving a predetermined packet from the base station, the predetermined packet including VoIP data,

wherein an amount of the VoIP data in the predetermined packet corresponds to the maximum scheduling delay, and

wherein the allocated buffer space in the jitter buffer corresponds to the amount of the VoIP data in the predetermined packet.

12. The method of claim 11, wherein the act of receiving the VoIP packets from the base station comprises:

receiving an initial burst packet from the base station prior to receiving any other VoIP packets, the initial burst packet including one or more VoIP packets,

unencapsulating the one or more VoIP packets from the initial burst packet; and

providing the unencapsulated one or more VoIP packets to the allocated buffer space, wherein the initial burst packet is the predetermined packet.

28. The method of claim 7, further comprising:

receiving VoIP packets from the base station and storing the VoIP packets in the jitter buffer;

determining whether a wait time has passed since establishing the communication with the base station; and

starting the VoIP decoding process after the wait time has passed.

29. The method of claim 28, wherein the wait time corresponds to the maximum scheduling delay.

13. A base station capable of performing VoIP (Voice over Internet Protocol) over mobile broadband, comprising:

a base band unit configured to communicate with a plurality of mobile wireless terminals via a radio interface; and

a base station controller operatively coupled to the base band unit and configured to control operations of the base band unit,

wherein, for a mobile wireless terminal among the plurality of mobile wireless terminals, the base band unit is configured to;

provide, via the radio interface, a maximum scheduling delay indication to the mobile wireless terminal, wherein the maximum scheduling delay indication corresponds to a maximum scheduling delay applicable to the mobile wireless terminal; and

provide, via the radio interface, the VoIP packets destined for the mobile wireless terminal.

14. The base station of claim 13, wherein the maximum scheduling delay indication is an explicit indication specifying one of an amount of time or an amount of data.

15. The base station of claim 14, wherein the base band unit is configured to provide the maximum scheduling delay indication prior to providing the VoIP packets.

16. The base station of claim 13,

wherein the base band unit is configured to:

package a predetermined packet, the predetermined packet including VoIP data, and

provide the predetermined packet to the mobile wireless terminal, and

wherein an amount of the VoIP data in the predetermined packet corresponds to the maximum scheduling delay.

17. The base station of claim 16,

wherein the base band unit is configured to:

encapsulate one or more VoIP packets into an initial burst packet, and

burst the initial burst packet to the mobile wireless terminal prior to providing any other VoIP packets to the mobile wireless terminal, and

wherein an amount of VoIP data in the initial burst packet is an implicit maximum scheduling delay indication.

18. The base station of claim 13, wherein the base band unit is configured to:

queue the VoIP packets destined to the mobile wireless terminal;

for each queued VoIP packet, determine whether the VoIP packet can be delivered to the mobile wireless terminal within the maximum scheduling delay based on a priority;

schedule a delivery of each VoIP packet that can be delivered within the maximum scheduling delay; and

discard each VoIP packet that cannot be delivered within the maximum scheduling delay.

30. The base station of claim 18, wherein the priority for each VoIP is based on a subscriber service level associated with the mobile wireless terminal and an origination time of the VoIP.

19. A method of reducing jitter for VoIP (Voice over Internet Protocol) over mobile broadband, comprising:

providing, via a radio interface, a maximum scheduling delay indication to a mobile wireless terminal, wherein the maximum scheduling delay indication is a maximum scheduling delay applicable to the mobile wireless terminal; and

providing, via the radio interface, VoIP packets destined for the mobile wireless terminal.

20. The method of claim 19, wherein the act of providing the maximum scheduling delay indication comprises explicitly providing the maximum scheduling delay indication as one of an amount of time or an amount of data.

21. The method of claim 20, wherein the act of providing the maximum scheduling delay indication to the mobile wireless terminal is performed prior to the act of providing the VoIP packets destined for the mobile wireless terminal.

22. The method of claim 19, wherein the act of providing the maximum scheduling delay indication comprises:

packaging VoIP data into a predetermined packet; and

providing the predetermined packet to the mobile wireless terminal,

wherein an amount of the VoIP data in the predetermined packet corresponds to the maximum scheduling delay indication.

23. The method of claim 22, wherein the act of providing the VoIP data into the predetermined packet and the act of providing the predetermined packet to the mobile wireless terminal comprise:

encapsulating one or more VoIP packets into an initial burst packet corresponding; and

bursting the initial burst packet to the mobile wireless terminal,

wherein the initial burst packet is the predetermined packet.

24. The method of claim 19, wherein the act of providing the VoIP packets destined for the mobile wireless terminal comprises:

queuing the VoIP packets destined to the mobile wireless terminal;

for each queued VoIP packet, determining whether the VoIP packet can be delivered to the mobile wireless terminal within the maximum scheduling delay based on a priority;

scheduling a delivery of each VoIP packet that can be delivered within the maximum scheduling delay; and

discarding each VoIP packet that cannot be delivered within the maximum scheduling delay.

25. A method of reducing jitter for VoIP (Voice over Internet Protocol) over mobile broadband, comprising:

preparing an initial burst packet, the initial burst packet having encapsulated therein one or more initial VoIP packets, wherein an amount of VoIP data in the initial burst packet corresponds to a maximum scheduling delay of the mobile wireless terminal;

bursting to the mobile wireless terminal from the base station the initial burst packet prior to providing any other VoIP packets after establishing communication between the base station and the mobile wireless terminal;

providing to the mobile wireless terminal from the base station remainder of the VoIP packets; and

decoding the one or more initial VoIP packets and the remainder of the VoIP packets from the mobile wireless terminal,

wherein the act of decoding starts as soon as the mobile wireless terminal receives the VoIP data without regard to whether or not a jitter buffer of the mobile wireless terminal is full or not.