Closed loop resource allocation

• US 6,563,810 B1
• Filed: 09/30/1999
• Issued: 05/13/2003
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Corazza, Giovanni E.
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): LEE, CHI HO A
• Application Number:
  US09/409,981
• Time in Patent Office: 1,321 Days
• Field of Search: 370/335, 370/318, 370/252, 370/465, 370/468, 370/230, 370/235, 370/331, 370/342, 370/329, 370/412, 370/431, 370/441, 370/450, 370/522, 370/433, 370/437, 370/454, 370/456, 370/459, 455/69, 455/450, 455/438, 455/452, 455/453, 455/445, 455/442, 455/451
• US Class Current: 370/335
• CPC Class Codes: H04B 2201/70705 Rate detection
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 72/04 Wireless resource allocation

Abstract

Method and apparatus for performing transmission data rate allocation in a high speed wireless communications network. A macro control loop with the network of base stations on one side and all the subscriber stations on the other side. Subscriber station selects a rate based on the amount of data queued for transmission (100). Adjusts this rate based on the available power headroom of the subscriber station (102). This adjusted transmission rate is then adjusted again to account for protection of base stations in the candidate set of the subscriber station (104). This rate is then adjusted in accordance with busy tone signals indicative of the loading conditions of active set base stations of the subscriber station (108). The base stations react to these action by refreshing measurements of their instantaneous traffic load and providing feedback in the form of soft busy tones. The algorithm is named Closed Loop Resource Allocation.

Claims

1. A method for determining reverse link transmission rate at a subscriber station comprising the steps of:

receiving a busy tone signal indicative of the reverse link loading from a first base station in an active set of said subscriber station;

receiving a busy tone signal indicative of the reverse link loading from a second base station in the active set of said subscriber station;

selecting one of said busy tone signals; and

determining said reverse link transmission rate in accordance with said selected one of said busy tone signals.

2. The method of claim 1 wherein said busy tones signals are indicated by an integer value where the loading indicated increases with the value of said integer value and wherein said step of selecting one of said busy tone signals comprises selecting the busy tone signal with the greatest value.

3. The method of claim 2 wherein said busy tone is transmitted as a two bit number and wherein

(0,0) indicates a scarcely loaded base station;

(0,1) indicates a stable base station;

(1,0) indicates a heavily loaded base station; and

(1,1) indicates a base station overload condition.

4. A method for determining reverse link transmission rate at a subscriber station comprising the steps of:

selecting an initial rate in accordance with the amount of data queued to be transmitted by said subscriber station;

adjusting said initial rate in accordance with at least one received busy tone value;

determining an energy difference metric in accordance with signal strengths from candidate base stations and active set base stations;

adjusting said initial rate in accordance with said energy difference metric to provide a second adjusted rate; and

wherein said step of adjusting said initial rate is performed on said second adjusted rate.

5. The method of claim 4 wherein said step of selecting an initial rate in accordance with the amount of data queued to be transmitted by said subscriber station, comprises the steps of:

determining whether the amount of data queued to be transmitted can be carried in a packet transmitted at the predetermined maximum data rate;

setting said initial rate to the predetermined maximum rate when the amount of data queued to be transmitted exceeds the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate;

setting said initial rate to a second rate which is less than said predetermined maximum rate when the amount of data queued to be transmitted is less than the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate; and

setting said initial rate to the less of the current value of the initial rate or twice the rate at which a previous frame was transmitted.

6. A method for determining reverse link transmission rate at a subscriber station comprising the steps of:

selecting an initial rate in accordance with the amount of data queued to be transmitted by said subscriber station;

adjusting said initial rate in accordance with at least one received busy tone value;

determining the amount of power headroom in the subscriber station;

adjusting said initial rate in accordance with said power headroom to provide a second adjusted rate;

wherein said step of adjusting said initial rate is performed on said second adjusted rate;

determining an energy difference metric in accordance with signal strengths from candidate base stations and active set base stations;

adjusting said second adjusted rate in accordance with said energy difference metric to provide a third adjusted rate; and

wherein said step of adjusting said initial rate is performed on said third adjusted rate.

7. A method for selecting a data rate for reverse link transmissions, comprising the steps of:

selecting an initial rate in accordance with the amount of data in a transmission buffer;

modifying said initial rate in accordance with a power headroom value to provide a first adjusted rate;

modifying said first adjusted rate in accordance with a candidate set protection value to provide a second adjusted rate; and

modifying said second adjusted rate in accordance with a received busy tone value to provide said selected reverse link transmission rate.

8. The method of claim 7 wherein said step of selecting an initial rate, comprises the steps of:

determining whether the amount of data queued to be transmitted can be carried in a packet transmitted at the predetermined maximum data rate;

setting said initial rate to the predetermined maximum rate when the amount of data queued to be transmitted exceeds the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate;

setting said initial rate to a second rate which is less than said predetermined maximum rate when the amount of data queued to be transmitted is less than the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate; and

setting said initial rate to the less of the current value of the initial rate or twice the rate at which a previous frame was transmitted.

9. The method of claim 7 wherein said step of selecting an initial rate, comprises the steps of:

determining whether said amount of data in said buffer exceeds a predetermined amount; and

setting a flag when said amount of data in said buffer exceeds a predetermined amount.

10. The method of claim 7 wherein said step of selecting an initial rate, comprises the steps of:

determining whether said amount of data in said buffer exceeds a predetermined amount; and

setting a flag when said amount of data in said buffer exceeds a predetermined amount.

11. The method of claim 7 wherein said step of modifying said initial rate in accordance with a power headroom value to provide a first adjusted rate, comprises:

determining the maximum power capable of being transmitted by said subscriber station; and

selecting the maximum rate capable of being transmitted at or below said maximum power capable of being transmitted by said subscriber station.

12. The method of claim 11 wherein said step of selecting the maximum rate comprises the steps of:

determining whether said subscriber station is in soft handoff; and

wherein said step of selecting the maximum rate is performed in accordance with said determination as to determining whether said subscriber station is in soft handoff.

13. The method of claim 11 wherein said step of selecting the maximum rate comprises the steps of:

determining distance between said subscriber station and an active set base station; and

wherein said step of selecting the maximum rate is performed in accordance with determining distance between said subscriber station and an active set base station.

14. The method of claim 11 wherein said step of selecting the maximum rate comprises the steps of:

determining the speed of said subscriber station; and

wherein said step of selecting the maximum rate is performed in accordance with the speed of said subscriber station.

15. The method of claim 11 wherein said step of modifying said first adjusted rate in accordance with a candidate set protection value to provide a second adjusted rate, comprising the steps of:

measuring the signal energy of at least one candidate set base station;

measuring the signal energy of at least one active set base station;

computing said candidate set protection value in accordance with said signal energy of at least one active set base station and said signal energy of at least one candidate set base station.

16. The method of claim 15 wherein said step of computing said candidate set protection value in accordance with said signal energy of at least one active set base station and said signal energy of at least one candidate set base station, comprising the steps of:

summing the energies of said signal energy of at least one active set base station to provide a summed active set energy;

summing the energies of said signal energy of at least one candidate set base station to provide a summed candidate set energy;

and wherein said step of computing said candidate set protection value is performed in accordance with the difference between said summed active set energy and said summed active set energy.

17. The method of claim 15 wherein said step of computing said candidate set protection value in accordance with said signal energy of at least one active set base station and said signal energy of at least one candidate set base station, comprising the steps of:

selecting a minimum energy active set base station of said signal energy of at least one active set base station;

selecting a maximum energy candidate set base station of said signal energy of at least one candidate set base station;

and wherein said step of computing said candidate set protection value is performed in accordance with the difference between the signal energy of said minimum energy active set base station and the signal energy of said maximum energy candidate set base station.

18. The method of claim 15 wherein said step of computing said candidate set protection value in accordance with said signal energy of at least one active set base station and said signal energy of at least one candidate set base station, comprising the steps of:

selecting a minimum energy active set base station of said signal energy of at least one active set base station;

summing the energies of said signal energy of at least one candidate set base station to provide a summed candidate set energy; and

wherein said step of computing said candidate set protection value is performed in accordance with the difference between the signal energy of said minimum energy active set base station and said summed active set energy.

19. The method of claim 15 wherein said step of computing said candidate set protection value in accordance with said signal energy of at least one active set base station and said signal energy of at least one candidate set base station, comprising the steps of:

selecting a maximum energy active set base station of said signal energy of at least one active set base station;

selecting a maximum energy candidate set base station of said signal energy of at least one candidate set base station;

and wherein said step of computing said candidate set protection value is performed in accordance with the difference between the signal energy of said maximum energy active set base station and the signal energy of said maximum energy candidate set base station.

20. The method of claim 7 wherein said step of modifying said second adjusted rate in accordance with a received busy tone value to provide said selected reverse link transmission rate is performed in accordance with a stochastic process.

21. The method of claim 20 wherein stochastic process is determined in accordance with the average number rate of transmission over a predetermined prior interval.

22. The method of claim 20 wherein stochastic process is determined in accordance with a buffer capacity flag.

23. The method of claim 22 wherein stochastic process is determined in accordance with the buffer capacity flag.

24. The method of claim 23 wherein the probability of increasing the transmission rate (p) is given by:

$p=\min <br><br>\left\{1,\frac{1+F_{\mathrm{Buffer}}/2}{N_{\mathrm{rates}}}<br><br>{\log }_2<br><br>\frac{R_{\max }}{R_{\mathrm{average}}}\right\},$

where R average is the average data rate in a predetermined number of previous transmissions, F_Buffer is the buffer full flag that in the exemplary embodiment assumes a value of zero or one where one indicates the buffer full condition, R_max as described previously is the maximum transmission rate of the subscriber station, N_Rates is the number of rates available for the subscriber station.

25. A subscriber station for transmitting high rate digital data comprising:

receiver for receiving a busy tone signal indicative of the reverse link loading from a first base station in an active set of said subscriber station, and for receiving a busy tone signal indicative of the reverse link loading from a second base station in the active set of said subscriber station; and

control processor for selecting one of said busy tone signals and determining said reverse link transmission rate in accordance with said selected one of said busy tone signals.

26. The subscriber station of claim 25 wherein said busy tones signals are indicated by an integer value where the loading indicated increases with the value of said integer value and wherein said step of selecting one of said busy tone signals comprises selecting the busy tone signal with the greatest value.

27. The method of claim 26 wherein said busy tone is received as a two bit number and wherein

(0,0) indicates a scarcely loaded base station;

(0,1) indicates a stable base station;

(1,0) indicates a heavily loaded base station; and

(1,1) indicates a base station overload condition.

28. A subscriber station for transmitting high speed digital data comprising:

a buffer for storing data for transmission by said subscriber station;

receiver for receiving a busy tone signal indicative of the reverse link loading from a first base station in an active set of said subscriber station, and for receiving a busy tone signal indicative of the reverse link loading from a second base station in the active set of said station; and

control processor for selecting one of said busy tone signals and determining said reverse link transmission rate in accordance with said selected one of said busy tone signals and the amount of data in said buffer.

29. The subscriber station of claim 28 further comprising:

wherein said control processor is further for determining the amount of power headroom in the subscriber station and for determining said transmission rate in accordance with said power.

30. The subscriber station of claim 28 wherein said control processor is further for determining an energy difference metric in accordance with signal strengths from candidate base stations and active set base stations and for determining said transmission rate in accordance with said energy difference metric to provide a second adjusted rate.

31. The subscriber station of claim 29 wherein said control processor is further for determining an energy difference metric in accordance with signal strengths from candidate base stations and active set base stations and for determining said transmission rate in accordance with said energy difference metric to provide a second adjusted rate.

32. The subscriber station of claim 28 wherein said control processor determines whether the amount of data queued to be transmitted can be carried in a packet transmitted at the predetermined maximum data rate selecting said transmission rate to a predetermined maximum rate when the amount of data queued to be transmitted exceeds the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate and setting said initial rate to a second rate which is less than said predetermined maximum rate when the amount of data queued to be transmitted is less than the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate.

33. The subscriber station of claim 29 wherein said control processor selects the maximum rate capable of reliable transmission by said subscriber station in accordance with said power headroom and selects the lesser of the initial rate and said maximum rate capable of reliable transmission by said subscriber station as said second adjusted rate.

34. A subscriber station for transmitting data at a selected rate of a set of possible rates, comprising:

buffer for storing an amount of data to be transmitted by said subscriber station;

receiver subsystem for receiving a busy tone signal indicative of a busy tone value;

control processor for selecting an initial rate in accordance with the amount of data in a transmission buffer, modifying said initial rate in accordance with a power headroom value to provide a first adjusted rate, modifying said first adjusted rate in accordance with a candidate set protection value to provide a second adjusted rate, and modifying said second adjusted rate in accordance with a received busy tone value to provide said selected reverse link transmission rate; and

transmitter for transmitting data at said selected data rate.

35. The subscriber station of claim 34 wherein said control processor determines whether the amount of data queued to be transmitted can be carried in a packet transmitted at the predetermined maximum data rate, sets said initial rate to the predetermined maximum rate when the amount of data queued to be transmitted exceeds the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate, sets said initial rate to a second rate which is less than said predetermined maximum rate when the amount of data queued to be transmitted is less than the amount of information that can be carried in a packet transmitted at the predetermined maximum data rate and sets said initial rate to the less of the current value of the initial rate or twice the rate at which a previous frame was transmitted.

36. The method of claim 34 wherein said control processor determines whether said amount of data in said buffer exceeds a predetermined amount and sets a flag when said amount of data in said buffer exceeds a predetermined amount.

37. The subscriber station of claim 35 wherein said control processor determines whether said amount of data in said buffer exceeds a predetermined amount sets a flag when said amount of data in said buffer exceeds a predetermined amount.

38. The subscriber station of claim 34 wherein said control processor determines the maximum power capable of being transmitted by said subscriber station and selects the maximum rate capable of being transmitted at or below said maximum power capable of being transmitted by said subscriber station.

39. The subscriber station of claim 38 wherein said control processor determines whether said subscriber station is in soft handoff and wherein said subscriber station selects the maximum rate is performed in accordance with said determination as to whether said subscriber station is in soft handoff.

40. The method of claim 38 wherein said control processor determines a distance between said subscriber station and an active set base station and selects the maximum rate is performed in accordance with determining distance between said subscriber station and an active set base station.

41. The subscriber station of claim 38 wherein said control processor determines the speed of said subscriber station and selects the maximum in accordance with the speed of said subscriber station.

42. The subscriber station of claim 38 wherein said control processor estimates the signal energy of at least one candidate set base station, estimates the signal energy of at least one active set base station, and computes said candidate set protection value in accordance with said signal energy of at least one active set base station and said signal energy of at least one candidate set base station.

43. The subscriber station of claim 42 wherein said control processor sums the energies of said signal energy of at least one active set base station to provide a summed active set energy, sums the energies of said signal energy of at least one candidate set base station to provide a summed candidate set energy, computes said candidate set protection value is performed in accordance with the difference between said summed active set energy and said summed active set energy.

44. The subscriber station of claim 42 wherein said control processor selects a minimum energy active set base station of said signal energy of at least one active set base station, selects a maximum energy candidate set base station of said signal energy of at least one candidate set base station, and computes said candidate set protection value is performed in accordance with the difference between the signal energy of said minimum energy active set base station and the signal energy of said maximum energy candidate set base station.

45. The subscriber station of claim 42 wherein said control processor selects a minimum energy active set base station of said signal energy of at least one active set base station, sums the energies of said signal energy of at least one candidate set base station to provide a summed candidate set energy, and computes said candidate set protection value is performed in accordance with the difference between the signal energy of said minimum energy active set base station and said summed active set energy.

46. The subscriber station of claim 42 wherein said control processor selects a maximum energy active set base station of said signal energy of at least one active set base station, selects a maximum energy candidate set base station of said signal energy of at least one candidate set base station and computes said candidate set protection value is performed in accordance with the difference between the signal energy of said maximum energy active set base station and the signal energy of said maximum energy candidate set base station.

47. The subscriber station of claim 34 wherein control processor selects said transmission rate in accordance with a stochastic process.

48. The subscriber station of claim 47 wherein stochastic process is determined in accordance with the average number rate of transmission over a predetermined prior interval.

49. The subscriber station of claim 47 wherein stochastic process is determined in accordance with the a buffer capacity flag.

50. The method of claim 49 wherein stochastic process is determined in accordance with a buffer capacity flag.

51. The method of claim 50 wherein the probability of increasing the transmission rate (p) is given by:

$p=\min <br><br>\left\{1,\frac{1+F_{\mathrm{Buffer}}/2}{N_{\mathrm{rates}}}<br><br>{\log }_2<br><br>\frac{R_{\max }}{R_{\mathrm{average}}}\right\},$

where R average is the average data rate in a predetermined number of previous transmissions, F_Buffer is the buffer full flag that in the exemplary embodiment assumes a value of zero or one where one indicates the buffer full condition, R_max as described previously is the maximum transmission rate of the subscriber station, N_Rates is the number of rates available for the subscriber station.