Data transmission in a wireless communication system

• US 20020075827A1
• Filed: 12/19/2000
• Published: 06/20/2002
• Est. Priority Date: 12/19/2000
• Status: Active Grant

• Current Assignee: LGS Innovations LLC (CACI International Incorporated)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Vitebsky, Stanley, Balogh, Dan Anthony, Burgess, John K., Cheng, Terry Si-Fong, Huang, Ching Yao
• Granted Patent: US 6,842,441 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0027 Scheduling of signalling, e.g. occurrence thereof
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data

Abstract

A method and apparatus for transmitting a burst of data over a supplemental channel on just one leg of a handoff by changing at least one of the parameters of the data to be transmitted over the supplemental channel as a function of the future and/or current characteristics of the communication link of the leg(s) of the handoff. This controlled parameters of the data can include the maximum allowed burst duration, and the type and/or amount of error coding of the data. The data is then transmitted over just one leg of handoff using the parameter. By changing the parameters of the data, the data may still be acceptably received at the mobile terminal over just one leg of the soft handoff even when the strength of the pilot signal used for the supplemental channel changes significantly. The invention thus, advantageously, delays or possibly obviates the need to establish a supplemental channel over additional legs of the soft handoff. This reduces the number of resources needed for the call, and therefore increases the capacity of the wireless communication system. In an illustrative embodiment of the invention the stability of the communication link is used as a way of ascertaining the future conditions of the communications link. A number of factors such as whether the call is in soft handoff, and/or the measurements of the pilot signal(s), and/or the measurements of the signal(s) on the supplemental channel can be used in assessing the stability of the communication link.

Claims

1. A method for use in a system where data is transmitted during a handoff, the handoff having at least two legs each being between a terminal and one of at least two sets of communication equipment, the method comprising the steps of:

responsive to a deterioration in at least one of the characteristics of a communication link that is part of at least one of the legs, changing at least one parameter of the data; and

transmitting a burst of data over just one of the legs using the at least one parameter.

2. The method of claim 1, wherein the at least one parameter is selected to allow the data to be received at an acceptable level of signal quality.

3. The method of claim 1, wherein the characteristics of the communication link comprise the current characteristics of the communication link.

4. The method of claim 1, wherein the characteristics of the communication link comprise the stability of the communication link.

5. The method of claim 1, wherein the at least one parameter comprises the maximum allowed burst duration.

6. The method of claim 5, wherein the transmitting step comprises:

establishing a secondary channel over just one leg responsive to the maximum allowed burst duration being at least as large as a threshold burst duration; and

transmitting the data burst over the secondary channel.

7. The method of claim 6, further comprising the step of responsive to the maximum allowed burst duration being smaller than the threshold burst duration transmitting the data burst over the primary channel.

8. The method of claim 1, wherein:

each set of communication equipment includes a transmitter; and

the communication link is a forward link.

9. The method of claim 1, wherein the characteristics of the communication link are obtained from a pilot strength measurement message.

10. The method of claim 1, wherein the characteristics of the communication link are based on characteristics of at least one pilot signal, each of the sets of the communication equipment transmitting one of the at least one pilot signals.

11. The method of claim 10, wherein the characteristics of the at least one pilot signal comprise whether an anchor set of the sets of communication equipment remains as the anchor set.

12. The method of claim 10, wherein the characteristics of at least one pilot signal comprise a strength of a pilot signal of an anchor set of the sets of communication equipment for a first predetermined number of measurements.

13. The method of claim 1, wherein the characteristics of the communication link are based on at least one of the following characteristics:

whether an anchor set of the sets of communication equipment remains as the anchor set;

a strength of a pilot signal of an anchor set of the sets of communication equipment for a first predetermined number of measurements;

the strength of the pilot signal of the anchor set of the sets communication equipment relative to a strength of a pilot signal of a non-anchor set of the sets of communication equipment;

the rate of change of the strength of the pilot signal of the anchor set of the sets of communication equipment; and

the rate of change of the strength of the pilot signal of the anchor set of the sets of communication equipment for a second predetermined number of measurements.

14. The method of claim 1, wherein the characteristics of the communication link are based on characteristics of a signal on a secondary channel.

16. The method of claim 15, wherein the second plurality of burst parameters is selected to allow the data to be received at an acceptable level of signal quality.

17. The method of claim 15, wherein the characteristics of the communication link comprise the current characteristics of the communication link.

18. The method of claim 15, wherein the characteristics of the communication link comprise the stability of the communication link.

19. The method of claim 15, wherein the at least one of the parameters comprises the maximum allowed burst duration.

20. The method of claim 19, wherein the step of transmitting a second burst of data comprises:

establishing a secondary channel over just one leg responsive to the maximum allowed burst duration being at least as large as a threshold burst duration; and

transmitting the data burst over the secondary channel.

21. The method of claim 20, further comprising the steps of responsive to the maximum allowed burst duration being smaller than the threshold burst duration transmitting the data burst over the primary channel.

22. The method of claim 15, wherein:

each set of communication equipment includes a transmitter; and

the communication link is a forward link.

23. The method of claim 15, wherein the characteristics of the communication link are obtained from a pilot strength measurement message.

24. The method of claim 15, wherein the characteristics of the communication link are based on characteristics of at least one pilot signal, each of the sets of the communication equipment transmitting one of the at least one pilot signals.

25. The method of claim 24, wherein the characteristics of the at least one pilot signal comprise whether an anchor set of the sets of communication equipment remains as the anchor set.

26. The method of claim 24, wherein the characteristics of at least one pilot signal comprise a strength of a pilot signal of an anchor set of the sets of communication equipment for a first predetermined number of measurements.

27. The method of claim 15, wherein the characteristics of the communication link are based on at least one of the following characteristics:

whether an anchor set of the sets of communication equipment remains as the anchor set;

a strength of a pilot signal of an anchor set of the sets of communication equipment for a first predetermined number of measurements;

the strength of the pilot signal of the anchor set of the sets communication equipment relative to a strength of a pilot signal of a non-anchor set of the sets of communication equipment;

the rate of change of the strength of the pilot signal of the anchor set of the sets of communication equipment; and

the rate of change of the strength of the pilot signal of the anchor set of the sets of communication equipment for a second predetermined number of measurements.

28. The method of claim 15, wherein the characteristics of the communication link are based on characteristics of a signal on a secondary channel.

30. The method of claim 29, wherein the maximum allowed burst duration is selected to allow the data to be received at an acceptable level of signal quality.

31. The method of claim 29, wherein the characteristics of the communication link comprise the current characteristics of the communication link.

32. The method of claim 29, wherein the characteristics of the communication link comprise the stability of the communication link.

33. The method of claim 32, wherein the transmitting step comprises:

establishing a secondary channel over just one leg responsive to the maximum allowed burst duration being at least as large as a threshold burst duration; and

transmitting the data burst over the secondary channel.

34. The method of claim 33, further comprising the step of responsive to the maximum allowed burst duration being smaller than the threshold burst duration transmitting the data burst over the primary channel.

35. The method of claim 29, wherein:

each set of communication equipment includes a transmitter; and

the communication link is a forward link.

36. The method of claim 29, wherein the characteristics of the communication link are obtained from a pilot strength measurement message.

37. The method of claim 29, wherein the characteristics of the communication link are based on characteristics of at least one pilot signal, each of the sets of the communication equipment transmitting one of the at least one pilot signals.

38. The method of claim 37, wherein the characteristics of the at least one pilot signal comprise whether an anchor set of the sets of communication equipment remains as the anchor set.

39. The method of claim 37, wherein the characteristics of at least one pilot signal comprise a strength of a pilot signal of an anchor set of the sets of communication equipment for a first predetermined number of measurements.

40. The method of claim 29, wherein the characteristics of the communication link are based on at least one of the following characteristics:

whether an anchor set of the sets of communication equipment remains as the anchor set;

a strength of a pilot signal of an anchor set of the sets of communication equipment for a first predetermined number of measurements;

the strength of the pilot signal of the anchor set of the sets communication equipment relative to a strength of a pilot signal of a non-anchor set of the sets of communication equipment;

the rate of change of the strength of the pilot signal of the anchor set of the sets of communication equipment; and

the rate of change of the strength of the pilot signal of the anchor set of the sets of communication equipment for a second predetermined number of measurements.

41. The method of claim 29, wherein the characteristics of the communication link are based on characteristics of a signal on a secondary channel.

15. A method for use in a system where a burst of data is transmitted during a handoff, the handoff having at least two legs each being between a terminal and one of at least two sets of communication equipment, the method comprising the steps of:

transmitting a first burst of data over just one of the legs using a first plurality of burst parameters;

responsive to a deterioration in at least one of the characteristics of a communication link that is part of at least one of the legs, selecting a second plurality of burst parameters where at least one of the parameters of the second plurality is different from the first plurality of burst parameters; and

transmitting a second burst of data over just one of the legs using the second set of burst parameters.

29. A method for use in a system where a burst of data is transmitted during a handoff, the handoff having at least two legs each being between a terminal and one of at least two sets of communication equipment, the method comprising the steps of:

determining a maximum allowed burst duration as a function of the characteristics of a communication link that is part of at least one of the legs;

transmitting the burst of data over just one of the legs, wherein the burst of data has a duration of at most the maximum allowed burst duration.