Transmission rate changes in communications networks

• US 20040087327A1
• Filed: 11/19/2002
• Published: 05/06/2004
• Est. Priority Date: 05/19/2000
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Guo, Yingjie Jay
• Granted Patent: US 7,317,931 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/223 predicting future states of the transmission
• CPC Class Codes: H04W 52/226 using past references to control power, e.g. look-up-table
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range

Abstract

A communications network includes first and second stations (10, 20), the first station (10) comprising a transmitter (18) and the second station (20) comprising a receiver (22). The network comprises a transition control portion (14) which is operable, prior to a change in a transmission rate of a preselected signal from the first station (10) to the second station (20), to cause transitional signals to be transmitted from the first station (10) to the second station (20) over the course of a transitional period expiring before the change is effected. The power levels of the transitional signals are varied over the course of the period in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by the change in transmission rate of that signal.

In another embodiment (FIG. 9) probing signals are transmitted prior to making such a rate change to probe a likely relationship between the transmission rate and transmission power after the change is effected.

Claims

1. A communications network including first and second stations, the said first station comprising a transmitter and the said second station comprising a receiver, the network comprising:

transition control means operable, prior to a change in a transmission rate of a preselected signal from said first station to said second station, to cause transitional signals to be transmitted from said first station to said second station over the course of a transitional period expiring before said change is effected, the power levels of said transitional signals being varied over the course of said period in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by said change in transmission rate of that signal.

2. A communications network as claimed in claim 1, wherein the said power levels of the said transitional signals are determined-based on a predetermined power profile.

3. A communications network as claimed in claim 1 or 2, further comprising condition measuring means for measuring one or more predetermined characteristics of the prevailing network conditions, wherein the said transition control means are operable to set the said power levels in dependence upon the said measured characteristics.

4. A communications network as claimed in any one of claims 1 to 3, wherein the said power levels of the said transitional signals are chosen so as to limit a rate of change of the said power levels to below a preselected maximum value.

5. A communications network as claimed in any one of claims 1 to 4, wherein the said change in transmission rate of the said preselected signal is an increase in transmission rate.

6. A communications network as claimed in claim 5, wherein the said power levels of the transitional signals are increased gradually over the course of the said transitional period.

7. A communications network as claimed in claim 5, wherein the said power levels of the said transitional signals are increased one after the next in a first phase of the transitional period to reach a maximum value and are then decreased one after the next in a second phase of the transitional period following the first phase.

8. A communications network as claimed in any one of claims 1 to 7, wherein at least one of the said transitional-signal power levels is set in dependence upon an estimate of the power level at which the said preselected signal is required to be transmitted when the said change is effected.

9. A communications network as claimed in claim 8, wherein the power level of a last one of the said transitional signals transmitted in the said transitional period is substantially equal to the said estimate of required power level.

33. A communications network as claimed in any preceding claim, wherein the said transitional signals, or the said probing signals as the case may be, are transmitted using the same channel as is used to transmit the said preselected signal.

34. A communications network as claimed in any one of claims 1 to 32, having respective first and second different channels available for transmission of signals from the said first station to the said second station, wherein the said probing signals, or the said transitional signals as the case may be, are transmitted using the said first channel and the said preselected signal is transmitted using the said second channel.

35. A communications network as claimed in any preceding claim, being a mobile communication network, one of the first and second stations being a base station of the mobile communications network and the other of the first and second station being a mobile station of the mobile communications network.

36. A communications network as claimed in any one of claims 1 to 34, being a mobile communications network, wherein each of the first and second stations is a user equipment of the mobile communications network.

37. A mobile communications network as claimed in claim 35, wherein the said first station is a base station of the network, the said second station is one user equipment of the network, the said first channel is a dedicated channel allocated individually to the said one user equipment, and the said second channel is a shared channel available for use on a shared basis by the said one user equipment and by at least one further user equipment of the network.

38. A mobile communications network as claimed in claim 37, wherein the said network is a UTRA network, the said first channel is a dedicated physical channel and the said second channel is a physical downlink shared channel.

39. A communications network as claimed in any preceding claim, wherein the said preselected signal carries data in the form of packets.

10. A communications network including first and second stations, the said first station comprising a transmitter and the said second station comprising a receiver, the network comprising:

probing means operable, prior to a change in a transmission rate of a preselected signal from said first to said second station, to cause probing signals to be transmitted from said first station to said second station at one or more probing power levels and further operable to measure results of transmission of said probing signals at the said one or more power levels and to employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

11. A communications network as claimed in claim 10, wherein said information is a transmission rate considered to be achievable at a preselected power level of said predetermined signal when said change is effected.

12. A communications network as claimed in claim 10, wherein said information is a power level at which said predetermined signal is to be transmitted, when said change is effected, to achieve a preselected transmission rate.

13. A communications network as claimed in claim 10, wherein said information includes both a suggested transmission rate and a suggested transmission power suitable for use when said change is effected.

14. A communications network as claimed in claim 10, wherein said information is a decision result indicating whether or not a preselected transmission rate is achievable at a transmission power level within a preselected range of allowable power levels of said first station.

15. A communications network as claimed in claim 10, wherein said information is a decision result indicating whether or not a preselected transmission rate is achievable at a preselected transmission power level.

16. A communications network as claimed in any one of claims 10 to 15, wherein the power levels of said probing signals are varied in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by said change in transmission rate of said preselected signal.

17. A communications network as claimed in any one of claims 10 to 16, wherein said results are measured in said first station.

18. A communications network as claimed in any one of claims 10 to 16, wherein said results are measured in said second station and said second station comprises transmission means operable to transmit such measurement results to said first station.

19. A communications network as claimed in any one of claims 10 to 18, wherein said one or more probing power levels at which said probing signals are transmitted are set in dependence upon said measurement results.

20. A communications network as claimed in any one of claims 10 to 19, wherein said measurement results indicate a level of interference being experienced in the network.

21. A communications network as claimed in any one of claims 10 to 20, wherein the said measurement results include one or more measures of signal-to-interference ratio of the said probing signals.

22. A communications network as claimed in any one of claims 10 to 21, wherein the said change in transmission rate is an increase in the transmission rate of the said preselected signal.

23. A communications network as claimed in any one of claims 10 to 22, wherein the probing means are operable to set at least one of the said probing power levels in dependence upon an estimate of the power level at which the preselected signal is required to be transmitted, when the said change is effected, to achieve a target transmission rate.

24. A communications network as claimed in claim 23, wherein the said probing signals are transmitted at at least two different probing power levels spanning a range of power levels that includes the said estimate of the required power level.

25. A communications network as claimed in any one of claims 10 to 24, wherein the said probing means are operable to perform such measurement of the results of transmission of the probing signals after transmission of a last one of the said probing signals.

26. A communications network as claimed in any one of claims 10 to 25, wherein the said probing means are operable to perform such measurement of the results of transmission of the probing signals during the course of transmission of those signals.

27. A communications network as claimed in claim 26, wherein the said probing means are operable to measure the results of the transmission of the probing signals at each different one of the said probing power levels.

28. A communications network as claimed in any one of claims 10 to 27, further comprising exception handling means operable, in the event that a target transmission rate of the said preselected signal when the said change is effected, or a target transmission power of the said preselected signal when that change is effected, is considered unachievable based on the said measurement results, to inhibit the said change from being made.

29. A communications network as claimed in any one of claims 10 to 28, further comprising exception handling means operable, in the event that a target transmission rate of the said preselected signal when the change is effected, or a target transmission power of the said preselected signal when that change is effected, is considered unachievable based on the said measurement results, to cause the said target transmission rate to be reduced and/or to cause the said target transmission power to be increased so as to improve the prospect of successful transmission of the said preselected signal when the said change is effected.

30. A communications network as claimed in any one of claims 10 to 29, wherein the said probing means are operable to set the said one or more probing power levels in dependence upon power control commands transmitted from the said second station to the said first station for use by power control means of the said first station to control a transmission power of signals sent from the said first station to the said second station.

31. A communications network as claimed in claim 30 wherein, in a probing period in which the said probing signals are transmitted from the said first station to the said second station, the said probing means sets a target signal quality measure, representing a target signal quality of the said probing signals as received at the said second station, in dependence upon a target data rate of the said preselected signal when the said change is effected, and the said second station produces its said power control commands in such a way as to tend to cause the said probing signals to be transmitted from the said first station at power levels which meet the said target signal quality measure on reception at the said second station.

32. A communications network as claimed in any one of claims 10 to 31, wherein at least one of the said probing signals carries rate information for use by the said second station in determining the said transmission rate of the said preselected signal when the said change is effected, and the said second station employs the carried rate information in measuring the said results of transmission of the said probing signals.

40. A base station, for use in a mobile communications network, comprising:

transition control means operable, prior to a change in a transmission rate of a preselected signal from the base station to a user equipment of the network, to cause transitional signals to be transmitted from the base station to said user equipment over the course of a transitional period expiring before said change is effected, the power levels of said transitional signals being varied over the course of said period in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by said change in transmission rate of that signal.

41. A user equipment, for use in a mobile communications network, comprising:

transition control means operable, prior to a change in a transmission rate of a preselected signal from the user equipment to a receiving station of the network, to cause transitional signals to be transmitted from the user equipment to said receiving station over the course of a transitional period expiring before said change is effected, the power levels of said transitional signals being varied over the course of said period in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by said change in transmission rate of that signal.

42. A communications method for use in a communications network including first and second stations, the said first station comprising a transmitter and the second station comprising a receiver, wherein:

prior to a change in a transmission rate of a preselected signal from said first station to said second station, transitional signals are caused to be transmitted from said first station to said second station over the course of a transitional period expiring before said change is effected, the power levels of said transitional signals being varied over the course of said period in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by said change in transmission rate of that signal.

43. A base station, for use in a mobile communications network, comprising:

probing means operable, prior to a change in a transmission rate of a preselected signal transmitted from the base station to a user equipment of the network, to cause probing signals to be transmitted from the base station to said user equipment at one or more probing power levels.

44. A base station as claimed in claim 43, wherein the said user equipment measures results of transmission of said probing signals at the said one or more power levels and transmits the measurement results to the base station, the base station further comprising:

result employing means arranged for receiving said measurement results from the user equipment and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

45. A base station as claimed in claim 43, further comprising:

result measurement means for measuring results of transmission of said probing signals at the said one or more power levels; and

result employing means arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

46. A user equipment, for use in a mobile communications network having a transmitting station that is operable, prior to a change in a transmission rate of a preselected signal transmitted from that station to the user equipment, to cause probing signals to be transmitted from said other station to the user equipment at one or more probing power levels, the user equipment comprising:

result measurement means for-measuring results of transmission of said probing signals at the said one or more power levels; and

result employing means arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

47. A user equipment, for use in a mobile communications network, comprising:

probing means operable, prior to a change in a transmission rate of a preselected signal transmitted from the user equipment to a receiving station of the network, to cause probing signals to be transmitted from the user equipment to said receiving station at one or more probing power levels.

48. A user equipment as claimed in claim 47, wherein the said receiving station measures results of transmission of said probing signals at the said one or more power levels and transmits the measurement results to the user equipment, the user equipment further comprising:

result employing means arranged for receiving said measurement results from the said receiving station and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

49. A user equipment as claimed in claim 47, further comprising:

result measurement means for measuring results of transmission of said probing signals at the said one or more power levels; and

result employing means arranged for receiving said measurement results and operable to-employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

50. A base station, for use in a mobile communications network having a user equipment that is operable, prior to a change in a transmission rate of a preselected signal transmitted from said user equipment to the base station, to cause probing signals to be transmitted from said user equipment to the base station at one or more probing power levels, the base station comprising:

result measurement means for measuring results of transmission of said probing signals at the said one or more power levels; and

result employing means arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.

51. A communications method for use in a communications network including first and second stations, the first station comprising a transmitter and the second station comprising a receiver, wherein:

prior to a change in a transmission rate of a preselected signal from said first to said second station, probing signals are caused to be transmitted from said first station to said second station at one or more probing power levels;

results of transmission of said probing signals at the said one or more power levels are measured; and

the measurement results are employed to provide information relating to a likely relationship between a transmission rate of the said predetermined signal and a transmission power thereof when the change is effected.