Method and apparatus for uplink transmission timing in a mobile communications system

• US 20030202490A1
• Filed: 04/24/2002
• Published: 10/30/2003
• Est. Priority Date: 04/24/2002
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Gunnarsson, Fredrik, Wiberg, Niclas, Englund, Eva, Bark, Gunnar
• Granted Patent: US 8,009,607 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0006 by adapting the transmission format
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 1/0022 in which mode-switching is influenced by the user
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

The present invention provides centralized load control at the radio network in order to control uplink interference in a cell while at the same time permitting adaptation to fast channel variations. The radio network sends to a mobile terminal a percentage of time that the mobile terminal may transmit over a radio channel in the uplink direction to the radio network. The mobile determines a current or future condition of the radio channel and restricts uplink transmissions based on the received percentage and the radio channel condition. Transmissions are restricted to times when the current or future condition is favorable up to the percentage amount. Channel condition favorability may be determined by the mobile station, in one example embodiment, by comparing the radio channel condition to an average condition of the channel, such as a local or moving average channel condition. Also in an example embodiment, the mobile may determine a current or future channel condition using transmit power control commands received from the radio network.

Claims

1. A method for controlling transmissions from a mobile terminal over radio channel to a radio network, comprising:

receiving from the radio network a percentage or fraction of time that the mobile terminal may transmit over the radio channel;

determining a current or future condition of the radio channel; and

restricting transmissions from the mobile terminal over the radio channel based on the percentage or fraction of time that the mobile terminal may transmit over the radio channel and the current or future condition of the radio channel.

2. The method in claim 1, wherein the transmissions are restricted to times when the current or future condition is favorable for transmission.

3. The method in claim 2, further comprising:

determining that a time is favorable for transmission by comparing the current or future condition of the radio channel to an average condition of the radio channel.

4. The method in claim 3, wherein the average condition is a local average condition.

5. The method in claim 2, further comprising:

determining a bit rate for the mobile terminal to transmit over the radio channel in view of the favorable channel condition.

6. The method in claim 5, further comprising:

limiting the bit rate for the mobile terminal to an average maximum bit rate.

7. The method in claim 2, further comprising:

determining a power level for the mobile terminal to transmit over the radio channel in view of the favorable channel condition.

8. The method in claim 1, further comprising:

determining an amount of time to transmit using the percentage of time the mobile terminal may transmit.

9. The method in claim 1, wherein transmissions from the mobile radio are restricted to times when the fast fading of the radio channel is constructive.

10. The method in claim 1, wherein the determining a current or future condition of the radio channel includes receiving channel condition messages from the radio network at a high frequency.

11. The method in claim 10, wherein the channel condition message is a transmit power control commands (TPCCs) to either increase or decrease transmit power.

12. The method in claim 11, further comprising:

determining a cumulative TPCC (CPTCC) value and an average channel condition value from received TPCCs;

comparing the CTPCC value to the average channel condition value; and

determining when to transmit based on the comparison.

13. The method in claim 12, further comprising considering an activity factor in determining when to transmit.

14. The method in claim 13, further comprising:

estimating an activity of the mobile radio based on a current activity level, and

setting an activity factor threshold based on an activity factor received from the radio network and the estimated activity.

15. The method in claim 13, further comprising:

receiving an activity factor from different radio base stations in the radio network, and

selecting a lowest one of the activity factors.

16. The method in claim 12, further comprising:

determining a local maximum CTPCC value and a local minimum CTPCC value;

determining a threshold using the local maximum CTPCC value and the local minimum CTPCC value and the percentage or fraction of time that the mobile terminal may transmit over the radio channel;

comparing the CTPCC value to the threshold; and

determining when to transmit based on the comparison.

17. The method in claim 16, wherein for a higher percentage, the threshold is higher, and for a lower percentage, the threshold is lower.

18. The method in claim 1, wherein the current condition is fast fading, and wherein transmissions from the mobile radio are restricted to times when the fast fading of the radio channel is constructive.

19. A method for controlling transmissions from a mobile terminal over radio channel to a radio network, comprising:

determining an activity factor that defines an amount of time relative to a total time that the mobile terminal may transmit over the radio channel;

receiving transmit power control commands (TPCCs) from the radio network to either increase or decrease transmit power; and

restricting transmissions from the mobile terminal over the radio channel based on the activity factor and the received TPCCs.

20. The method in claim 19, wherein the received TPCCs indicate a condition of the radio channel.

21. The method in claim 20, wherein the condition is a current or future condition of the radio channel.

22. The method in claim 19, further comprising:

using the received TPCCs to determine whether the radio channel is in a constructive or destructive fade,

wherein the restricting includes transmitting only during a constructive fade.

23. The method in claim 19, further comprising:

determining a cumulative TPCC (CTPCC) value and an average channel condition value from the received TPCCs;

comparing the CTPCC value to the average channel condition value; and

determining when to transmit based on the comparison.

24. The method in claim 23, wherein the average channel condition is determined using a low pass filter.

25. The method in claim 24, wherein the averaged TPCC value is determined using the following:

P<sub>filt—

new</sub>=λ

*P<sub>filt—

old</sub>+(1−

λ

)*CTPCC_new,

wherein P<sub>filt—

new</sub>is a new average channel condition value, λ

is a constant between 0 and 1, P<sub>filt—

old</sub> is a previous average channel condition value, and CPTCC is the cumulative sum of the TPCCs over a predetermined time period.

26. The method in claim 25, further comprising:

transmitting when CTPCC_new<

P<sub>filt—

new</sub>+ƒ

(af),

wherein ƒ

(af) is parameter that takes into account an activity factor (af).

27. The method in claim 26, wherein ƒ

(af) is determined using one of the following;

ƒ

₁(af)=ƒ

_max*2*(af−

0.5)ƒ

₂(af)=ƒ

_max*8*(af−

0.5)³*sign(af−

0.5).

28. The method in claim 23, further comprising:

determining a local maximum CTPCC value CPTCC_max and a local minimum CTPCC value CPTCC_min;

determining a threshold using the local maximum CTPCC value and the local minimum CTPCC value and the activity factor (af);

comparing a CTPCC value to the threshold; and

determining when to transmit based on the comparison.

29. The method in claim 28, wherein the

threshold=CTPCC_min+af*(CTPCC_max−

CTPCC_min)

wherein the mobile station transmits only when the current CTPCC value is less than the threshold, and

wherein for a higher activity factor, the threshold is higher, and for a lower percentage, the threshold is lower.

30. The method in claim 26, wherein the activity factor is determined based on statistical variations in a difference between CTPCC and P_filt—

_new.

31. A method for controlling uplink transmissions from active mobile terminals over radio channel to a radio network, comprising:

determining an activity factor for each of the mobile terminals defining an amount of time up to a total time that the mobile terminal may transmit over the radio channel based on a desired uplink load for a cell area;

sending a corresponding activity factor to each of the mobile terminals;

determining transmit power control commands for each of the mobile terminals based on channel condition information; and

sending the transmit power control commands to each of the mobile terminals,

wherein the radio network controls uplink load in the cell area using the activity factors and the transmit power control commands.

32. The method in claim 31, wherein each of the mobile terminals determines when to transmit to the radio network based on its activity factor and received transmit power control commands.

33. The method in claim 31, wherein the activity factor is sent to each mobile terminal less frequently than the transmit power control commands.

34. The method in claim 31, further comprising:

determining an average maximum bit rate for each of the mobile terminals, and

sending the average maximum bit rates to each of the mobile terminals,

wherein the radio network controls the uplink load in the cell using the average maximum bit rates.

35. A mobile terminal configured to transmit over radio channel to a radio network, comprising:

radio transceiving circuitry for transmitting to and receiving from the radio network, and

electronic circuitry coupled the radio transceiving circuitry and configured to;

determine a percentage or fraction of time that the mobile terminal may transmit over the radio channel;

determine a current or future condition of the radio channel; and

restrict transmissions from the mobile terminal over the radio channel based on the percentage or fraction of time that the mobile terminal may transmit over the radio channel and the current or future condition of the radio channel.

36. The mobile terminal in claim 35, wherein the electronic circuitry is configured to restrict transmissions to times when the current or future condition is favorable for transmission.

37. The mobile terminal in claim 36, wherein the electronic circuitry is configured to determine that a time is favorable for transmission by comparing the current or future condition of the radio channel to an average condition of the radio channel.

38. The mobile terminal in claim 36, wherein the average condition is a local average condition.

39. The mobile terminal in claim 36, wherein the electronic circuitry is configured to determine a bit rate for the mobile terminal to transmit over the radio channel in view of the favorable channel condition.

40. The mobile terminal in claim 39, wherein the electronic circuitry is configured to limit the bit rate to an average maximum bit rate.

41. The mobile terminal in claim 35, wherein the electronic circuitry is configured to determine a power level for the mobile terminal to transmit over the radio channel in view of the favorable channel condition.

42. The mobile terminal in claim 35, wherein the electronic circuitry is configured to determine an amount of time to transmit using the percentage of time the mobile terminal may transmit.

43. The mobile terminal in claim 35, wherein the electronic circuitry is configured to restrict transmissions from the mobile radio to times when the fast fading of the radio channel is constructive.

44. The mobile terminal in claim 35, wherein the electronic circuitry is configured to receive channel condition messages from the radio network at a high frequency.

45. The mobile terminal in claim 44, wherein the channel condition message is a transmit power control command (TPCC) to either increase or decrease transmit power.

46. The mobile terminal in claim 45, wherein the electronic circuitry is configured to compare a cumulative TPCC (CTPCC) value to an average channel condition value and to determine when to transmit based on the comparison.

47. The mobile terminal in claim 46,, wherein the electronic circuitry is configured to consider an activity factor in determining when to transmit.

48. The mobile terminal in claim 47, wherein the electronic circuitry is configured to:

estimate an activity of the mobile radio based on a current activity level, and

set an activity factor threshold based on an activity factor received from the radio network and the estimated activity.

49. The mobile terminal in claim 47, wherein the electronic circuitry is configured to:

receive an activity factor from different radio base stations in the radio network, and

select a lowest one of the activity factors.

50. The mobile terminal in claim 46, wherein the electronic circuitry is configured to:

determine a local maximum CTPCC value and a local minimum CTPCC value;

determine a threshold using the local maximum CTPCC value and the local minimum CTPCC value and the percentage or fraction of time that the mobile terminal may transmit over the radio channel;

compare the CTPCC value to the threshold; and

determine when to transmit based on the comparison.

51. The mobile terminal in claim 40, wherein for a higher percentage, the threshold is higher, and for a lower percentage, the threshold is lower.

52. The mobile terminal in claim 35, wherein the current condition is fast fading, and wherein the electronic circuitry is configured to restrict transmissions from the mobile radio to times when the fast fading of the radio channel is constructive.

53. A radio network including one or more nodes for controlling uplink transmissions from mobile terminals over radio channel to a radio network, comprising:

radio transceiving circuitry for transmitting to and receiving from mobile terminals, and

electronic circuitry configured to perform the following tasks;

determine an activity factor for each of the mobile terminals that defines an amount of time relative to a total time that the mobile terminal may transmit over the radio channel based on a desired uplink load for a cell area;

send a corresponding activity factor to each of the mobile terminals;

determine transmit power control commands for each of the mobile terminals based on channel condition information; and

send the transmit power control commands to each of the mobile terminals,

wherein the radio network controls uplink load in the cell area using the activity factors and the transmit power control commands.

54. The radio network in claim 53, wherein each of the mobile terminals determines when to transmit to the radio network based on its activity factor and received transmit power control commands.

55. The radio network in claim 53, wherein the electronic circuitry is configured to send the activity factor to each mobile terminal less frequently than the transmit power control commands.

56. The radio network in claim 53, wherein the electronic circuitry is configured to:

determine an average maximum bit rate for each of the mobile terminals, and

send the average maximum bit rates to each of the mobile terminals,

wherein the radio network controls the uplink load in the cell using the average maximum bit rates.