Method and system for determining an estimate of a transmission time of a packet

• US 6,205,125 B1
• Filed: 07/31/1998
• Issued: 03/20/2001
• Est. Priority Date: 07/31/1998
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Scribano, Gino Anthony, Proctor, Lee Michael
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Tran, Maikhanh
• Application Number:
  US09/126,827
• Time in Patent Office: 963 Days
• Field of Search: 370/328, 370/331, 370/333, 370/335, 370/342, 370/350, 370/519, 370/252, 370/238, 375/356, 375/267, 375/299, 375/347, 455/442, 455/67.6, 455/502, 455/436
• US Class Current: 370/328
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04B 7/2684 Synchronisation of a mobile station with more than one base station
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time
• CPC Class Codes: H04W 92/12 between access points and access point controllers

Abstract

A method and apparatus for determining the transmission time of packets of information in a communication system includes a temporal offset processor (330) which receives transmission delay information from a delay analyzer (315) and soft handoff state information from a control processor (320). This information is used to determine a temporal offset for packets of information. The temporal offset is used by a network arbiter (350) to determine when the associated packet should be transferred in time.

Claims

1. A method for determining a time of transmission of packets of information in a communication system, comprising the steps of:

receiving a first packet of information associated with a communication between a first mobile unit and a first base site transmitter and a second base site transmitter;

comparing a transmission delay associated with the first base site transmitter and a transmission delay associated with the second base site transmitter;

receiving additional packets of information at a network arbiter; and

determining an estimate of the time of transmission of the first packet and the additional packets based, at least in part, on the comparison,

wherein the additional packets of information are associated with independent communications between additional mobile units and at least the first base site transmitter, and

wherein the step of determining the estimate of the time of transmission comprises the steps of

determining a plurality of differences between a transmission delay associated with the first base site transmitter and the transmission delays associated with a plurality of further base site transmitters, and

determining the estimate of the time of transmission of the first packet and the additional packets based, at least in part, on the plurality of differences.

2. The method of claim 1, wherein the step of comparing further comprises the step of determining a difference in transmission delay associated with the first base site transmitter and the transmission delay associated with the second base site transmitter.

3. The method of claim 2, wherein the transmission delay associated with the first base site transmitter is the transmission delay between a first selector and the first base site transmitter.

4. The method of claim 3, wherein the transmission delay associated with the second base site transmitter is the transmission delay between the first selector and the second base site transmitter.

5. The method of claim 3, wherein the first selector resides in a base site controller.

6. The method of claim 1 further comprising the steps:

generating the first packet of information at a base station controller;

inserting into the first packet a data field containing a packet temporal offset, where the packet temporal offset is based, at least in part, on a difference in transmission delay associated with the first base site transmitter and the transmission delay associated with the second base site transmitter; and

transmitting the first packet of information from the base station controller to a network arbiter.

7. The method of claim 6, wherein the network arbiter determines the packet temporal offset for the first packet by extracting the inserted data field.

8. The method of claim 7, wherein the network arbiter determines a packet delay offset, the packet delay offset being based, at least in part, on the packet temporal offset.

9. The method of claim 8, wherein the time of transmission of the first packet of information is further based on the packet delay offset.

10. The method of claim 6 further comprising the step of determining a type of information contained in the first packet of information.

11. The method of claim 10 wherein the packet temporal offset is further based on the type of information contained in the first packet of information.

12. The method of claim 6, wherein the network arbiter determines a network delay offset which is based, at least in part, on a user configurable parameter.

13. The method of claim 6, further comprising the steps:

determining a plurality of differences between a transmission delay associated with the first base site transmitter and the transmission delays associated with a plurality of further base site transmitters; and

determining a network delay offset, where the network delay offset is based, at least in part, on the plurality of differences.

14. The method of claim 7, further comprising the steps:

determining a first location in a first data buffer, the first location being based, at least in part, on a packet delay offset; and

determining whether the first location in a first data buffer can accommodate the first packet of information.

15. The method of claim 14, wherein the first location accommodates the first packet of information and the first packet of information is placed in the first location of the first data buffer.

16. The method of claim 14, wherein the first location cannot accommodate the first information packet, the method further comprising the steps:

determining a second location in the first data buffer, the location being based, at least in part, on the first location; and

determining whether the second location in the first data buffer can accommodate the first packet of information.

17. The method of claim 16, wherein the second location cannot accommodate the first packet of information, the method further comprising the steps of:

determining a transmission time associated with the second location in the first data buffer;

determining a packet discard time, the packet discard time being based, at least in part, on the packet delay offset; and

determining whether the packet discard time is less than the transmission time.

18. The method of claim 17, further comprising the step of discarding the first packet of information when the packet discard time is less than the transmission time.

19. The method of claim 17, further comprising the step of placing the first packet of information in the second location of the first data buffer when the packet discard time is not less than the transmission time.

20. The method of claim 1, further comprising the steps:

receiving a second packet of information, associated with a communication between a second mobile unit and at least the first base site transmitter and the second base site transmitter;

determining a type of information contained in the first packet of information;

determining the type of information contained in the second packet of information; and

determining the time of transmission of the first packet, second packet and additional packets based, at least in part, on the type of information contained in the first packet of information.

21. The method of claim 20, wherein the step of determining the time of transmission is further based on the type of information contained in the second packet of information.

22. The method of claim 21, wherein the first packet of information is determined to contain encoded speech and the second packet of information is determined to contain user data, the method further comprising transmitting the first packet of information before transmitting the second packet of information.

23. A system for determining a time of transmission of packets of information in a communication system comprising:

means for receiving a plurality of packets of information;

means for comparing a transmission delay associated with a first base site transmitter and a transmission delay associated with a second base transmitter; and

means for determining an estimate of the time of transmission of the plurality of packets based, at least in part on the comparison.

24. The system of claim 23, further comprising;

means for determining the difference between the transmission delay associated with the first base site transmitter and the transmission delay associated with the second base site transmitter; and

means for determining the time of transmission of the plurality of packets further based on the difference.

25. A system for determining a time of transmission of packets of information in a communication system comprising:

means for receiving a plurality of packets of information;

means for determining a type of information contained in the plurality of packets of information;

means for comparing a transmission delay associated with a first base site transmitter and a transmission delay associated with a second base transmitter; and

means for determining an estimate of a time of transmission of the plurality of packets based on the comparison and the type of information.

26. The system of claim 25, wherein the network arbiter further comprises:

means for determining whether the first buffer location contains an untransmitted packet of information; and

means for determining a second buffer location if the first buffer location contains an untransmitted packet of information.

27. The system of claim 26, wherein the network arbiter further comprises means for inserting the packet of information into the first buffer location if the first buffer location does not contain an untransmitted packet of information.

28. The system of claim 26, wherein the network arbiter further comprises:

means for determining a transmission time associated with the second location;

means for determining a packet discard time, the packet discard time being based, at least in part, on the packet temporal offset;

means for comparing the packet discard time and the transmission time; and

means responsive to the comparison for discarding the packet of information.