Methods and apparatus for implementing and using a rate indicator

• US 20060205396A1
• Filed: 09/19/2005
• Published: 09/14/2006
• Est. Priority Date: 03/08/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Jin, Hui, Richardson, Tom
• Granted Patent: US 7,974,253 B2
• Time in Patent Office: Days
• US Class Current: 455/422.100
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0033 arrangements specific to the transmitter

Abstract

A base station selects and assigns uplink segments to specific wireless terminals. The base station estimates potential system interference levels, selects, assigns, and transmits a maximum uplink rate indicator value to a wireless terminal indicating the maximum uplink data rate that the wireless terminal is permitted to use. The wireless terminal receives the maximum data rate indicator and selects an uplink data rate to use which is less than or equal to the maximum data rate indicator level. The selection includes consideration of data amounts, data importance, communications channel quality, changes affecting the channel and/or power information. The wireless terminal encodes information indicative of the selected used rate with the user data/information to be transmitted by placing additional energy on a subset of the uplink signals. The base station receives the uplink signals including user data/information and data rate. The base station extracts the data rate used and utilizes the data rate to demodulate and decode the uplink user data/information.

Claims

1. A method of operating a base station in a wireless communications system including at least one wireless terminal which interacts with said base station via a wireless communications channel, the method comprising:

selecting a maximum uplink data transmission rate to be used by said wireless terminal when transmitting at least some information to said base station, said maximum uplink data transmission rate being one of a plurality of possible transmission data rates;

transmitting a maximum uplink data rate indicator to said wireless terminal, said maximum uplink data rate indicator indicating the selected maximum uplink data transmission rate which is the maximum uplink data transmission rate said wireless terminal is permitted to use when transmitting said at least some information; and

receiving from the wireless terminal data communicated over the wireless communications channel data transmitted at an uplink data transmission rate selected by the wireless terminal that is no greater than the selected maximum uplink data transmission rate indicated to said wireless terminal by the transmitted maximum uplink data rate indicator.

2. The method of claim 1, further comprising:

assigning at least some uplink traffic segments to said wireless terminal to be used in communicating data to said base station, said uplink traffic channel segments being wireless communications channel segments dedicated to communicating uplink signals to said base station; and

transmitting uplink traffic segment assignment information to said wireless terminal over said wireless communications channel.

3. The method of claim 2, further comprising:

repeating said steps of selecting, transmitting a maximum uplink data rate indicator, assigning at least some uplink traffic segments and transmitting uplink traffic segment assignment information over a period of time.

4. The method of claim 3, wherein said step of selecting a maximum uplink data transmission rate is performed once each time said step of assigning at least some uplink traffic segments is performed in said period of time.

5. The method of claim 1, said step of selecting the maximum uplink data transmission rate including:

making the selection based on the quality of said wireless communications channel.

6. The method of claim 5, further comprising:

estimating the interference that will be caused to other wireless terminals if said wireless terminal transmits uplink signals using at least one data transmission rate being considered for selection as the maximum uplink data transmission rate; and

wherein said step of selecting the maximum uplink data transmission rate is further based on an amount of interference to other wireless terminals which will be caused by uplink transmissions from said wireless terminal when said selected maximum uplink data rate is used.

7. The method of claim 6, wherein the base station is operated to:

assign at least one uplink communications segment to be used for transmitting the uplink signals;

communicating said segment assignment information to said wireless terminal; and

wherein a number of segments assigned to the wireless terminal at a point in time is based on an estimate of the amount of data to be transmitted by said wireless terminal.

8. The method of claim 1, wherein the selected maximum uplink data transmission rate is one of a plurality of possible maximum uplink data transmission rates which can be indicated, the number which can be indicated being fewer than the number of uplink data rates which can be selected and used by said wireless terminal for the transmission of uplink signals.

9. The method of claim 1, wherein the maximum uplink data rate indicator includes, at most, a maximum number of bits that is less than the number of bits required to uniquely specify the full set of uplink data transmission rates which can be used by said wireless terminal.

10. The method of claim 1, further comprising:

receiving power information from said wireless terminal; and

wherein said step of selecting the maximum uplink data transmission rate is performed as a function of the power available to said wireless terminal as indicated by said received power information.

11. The method of claim 2, further comprising:

receiving uplink data rate information from the wireless terminal indicating an uplink data transmission rate used by said wireless terminal to communicate data to said base station.

12. The method of claim 11, wherein receiving utilized uplink data rate information is received with data transmitted at the data rate indicated by said utilized uplink data rate information.

13. The method of claim 12, wherein said utilized uplink data rate information is indicated by the location of additional energy beyond the energy used to communicate said data on a predetermined subset of one or more signals used to communicate the data, the subset corresponding to the uplink data rate used to communicate said data, said one or more signals being tones of an orthogonal frequency division multiplexed signal.

14. The method of claim 13, wherein said additional energy is a function of the data rate selected.

15. The method of claim 13, wherein said additional energy is a function of the lowest data rate.

16. The method of claim 15, wherein said additional energy is at least 2 dB above the energy used to transmit the data.

17. A base station in a wireless communications system including at least one wireless terminal which interacts with said base station via a wireless communications channel, the base station comprising:

means for selecting a maximum uplink data transmission rate to be used by said wireless terminal when transmitting at least some information to said base station, said maximum uplink data transmission rate being one of a plurality of possible transmission data rates;

means for transmitting a maximum uplink data rate indicator to said wireless terminal, said maximum uplink data rate indicator indicating the selected maximum uplink data transmission rate which is the maximum uplink data transmission rate said wireless terminal is permitted to use when transmitting said at least some information; and

means for receiving from the wireless terminal data communicated over the wireless communications channel, said communicated data transmitted at an uplink data transmission rate selected by the wireless terminal that is no greater than the selected maximum uplink data transmission rate indicated to said wireless terminal by the transmitted maximum uplink data rate indicator.

18. The base station of claim 17, further comprising:

means for assigning at least some uplink traffic segments to said wireless terminal to be used in communicating data to said base station, said uplink traffic channel segments being wireless communications channel segments dedicated to communicating uplink signals to said base station; and

means for transmitting uplink traffic segment assignment information to said wireless terminal over said wireless communications channel.

19. The base station of claim 18, further comprising:

means for controlling the base station to repeat said steps of selecting, transmitting a maximum uplink data rate indicator, assigning at least some uplink traffic segments and transmitting uplink traffic segment assignment information over a period of time.

20. The base station of claim 19, wherein said means for controlling includes means for causing the base station to select a maximum uplink data transmission rate once each time the base station assigns at least some uplink traffic segments to be used in a dedicated manner by wireless terminal.

21. The base station of claim 17, wherein said means for selecting the maximum uplink data transmission rate including:

means for making the selection based on the quality of said wireless communications channel.

22. The base station of claim 21, further comprising:

means for estimating the interference that will be caused to other wireless terminals if said wireless terminal transmits uplink signals using at least one data transmission rate being considered for selection as the maximum uplink data transmission rate; and

wherein said means for selecting the maximum uplink data transmission rate bases the selection on an amount of interference to other wireless terminals which will be caused by uplink transmissions from said wireless terminal when said selected maximum uplink data rate is used.

23. A method of operating a wireless terminal in a wireless communications system including at least one base station which interacts with said wireless terminal via a wireless communications channel, the method comprising:

receiving a maximum uplink data rate indicator from said base station, said maximum uplink data rate indicator indicating a maximum uplink data transmission rate said wireless terminal is permitted to use;

selecting an uplink transmission data rate to use from a plurality of possible uplink transmission data rates which are less than or equal to said maximum uplink data transmission rate; and

transmitting data to said base station over the wireless communications link using said selected uplink data transmission rate.

24. The method of claim 23, further comprising:

receiving assignment information indicating at least one uplink segment assigned to said wireless terminal by said base station for use in communicating uplink signals, said maximum uplink data rate indicator indicating the maximum uplink data transmission rate which can be used in said at least one uplink segment assigned to said wireless terminal.

25. The method of claim 24, wherein the maximum uplink data rate indicator includes at most, a number of bits which is less than the number of bits required to uniquely identify the plurality of possible uplink data transmission rates which can be selected by the wireless terminal for transmitting uplink signals.

26. The method of claim 23, wherein selecting an uplink data transmission rate includes:

using information on the power available as a factor in selecting the uplink data transmission rate to use.

27. The method of claim 23, wherein said selecting of an uplink data transmission rate is further performed as a function of the amount of data to be transmitted to said base station.

28. The method of claim 27, wherein said selecting of an uplink data transmission rate is further performed as a function of information stored in said wireless terminal relating to changes in said wireless communications channel.

29. The method of claim 28, wherein said selecting of an uplink data transmission rate is further performed as a function of the importance of the data to be transmitted.

30. The method of claim 24, further comprising:

communicating uplink data rate information to said base station, said uplink data rate information indicating an uplink data transmission rate used by said wireless terminal.

31. The method of claim 30, wherein communicating said uplink data rate information includes:

transmitting said uplink data rate information with the data transmitted at the indicated data rate.

32. The method of claim 31, wherein said uplink data rate information is indicated by placing additional energy beyond the energy used to communicate said data on a predetermined subset of signals used to communicate the data, the subset corresponding to the uplink data rate used to communicate said data.

33. The method of claim 32, wherein said additional energy is a function of the data rate selected.

34. The method of claim 32, wherein said additional energy is a function of the lowest data rate.

35. The method of claim 34, wherein said additional energy is at least 2 dB above the energy used to transmit the data.

36. The method of claim 27, wherein said selecting of an uplink data transmission rate is further performed as a function of the quality of said wireless communications channel as detected by said wireless terminal.

37. A wireless terminal for use in a wireless communications system including at least one base station which interacts with said wireless terminal via a wireless communications channel, the wireless terminal comprising:

means for receiving a maximum uplink data rate indicator from said base station, said maximum uplink data rate indicator indicating a maximum uplink data transmission rate said wireless terminal is permitted to use;

means for selecting an uplink data transmission rate to use from a plurality of possible uplink data transmission rates which are less than or equal to said maximum uplink data transmission rate; and

means for transmitting data to said base station over the wireless communications link using said selected uplink data transmission rate.

38. The wireless terminal of claim 37, wherein said means for receiving includes:

means for detecting assignment information indicating at least one uplink segment assigned to said wireless terminal by said base station for use in communicating uplink signals, said maximum uplink data rate indicator indicating the maximum uplink data transmission rate which can be used in said at least one uplink segments assigned to said wireless terminal.

39. The wireless terminal of claim 38, wherein the maximum uplink data rate indicator includes at most, a number of bits which is less than the number of bits required to uniquely identify the plurality of possible uplink data transmission rates which can be selected by the wireless terminal for transmitting uplink signals.

40. The wireless terminal of claim 37, wherein said means for selecting an uplink data transmission rate includes:

means for using information on the power available as a factor in selecting the uplink data transmission rate to use.

41. The wireless terminal of claim 37, wherein means for selecting of an uplink data transmission rate selects the uplink data transmission rate as a function of the amount of data to be transmitted to said base station.

42. The wireless terminal of claim 37, wherein means for selecting of an uplink data transmission rate selects the uplink data transmission rate as a function of the importance of the data to be transmitted to said base station.