Transmitter directed code division multiple access system using path diversity to equitably maximize throughput

• US 6,449,490 B1
• Filed: 06/30/1999
• Issued: 09/10/2002
• Est. Priority Date: 05/24/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tse, David Ngar Ching, Black, Peter J., Holtzman, Jack M., Chaponniere, Etienne F.
• Primary Examiner(s): CRAVER, CHARLES R
• Assistant Examiner(s): Woldetatios, Yemane
• Application Number:
  US09/345,700
• Time in Patent Office: 1,168 Days
• Field of Search: 370/238, 370/252, 370/329, 370/335, 370/342, 370/441, 370/468, 370/330, 370/341, 370/344, 455/450, 455/452, 455/434, 455/445, 455/464, 455/507
• US Class Current: 455/507
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A transmitter directed, distributed receiver using path diversity provided by the distribution of the receiver. Advantage is taken of the uncorrelated variations over time in the condition of channels between a common transmitter and several users. The greater the variation in the channel condition of a particular channel over time, the greater the increase in total system throughput provided. An access metric represents the instantaneous channel condition of the communication system between each user and the transmitter with respect to the average channel condition of each channel. Alternatively, the access metric represent the instantaneous channel condition with respect to the average data throughput over that channel. The common transmitting station uses the access metric to directly compare the desirability of granting each channel access with the desirability of granting each other channel access. The user that has the greatest access metric is provided access to the channel.

Claims

1. A method for determining to which users, from among a plurality of users, access to a communication system is to be provided, such access being provided at any one time to a group of users that includes less than all of the plurality of users, such access being provided to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the users and providing communication between the associated user and a common transmitting station, the method comprising the steps of:

a) determining for each channel, a value representing the amount of data transmitted on the channel over a predetermined amount of time;

b) receiving a value representing the highest data rate at which each channel can currently receive data;

c) for each channel, determining a ratio of the received value representing the highest data rate, with respect to the value representing the amount of data transmitted; and

d) transmitting over the channel associated with the highest ratio.

10. The method of claim 1, wherein the indication of an instantaneous channel condition is an indication of the rate at which the user can receive transmissions from the common transmitting station.

2. A method for determining to which users, from among a plurality of users, access to a communication system is to be provided, such access being provided at any one time to a group of users that includes less than all of the plurality of users, such access being provided to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the users and providing communication between the associated user and a common transmitting station, the method comprising the steps of:

a) receiving an indication of a channel condition of a channel associated with each user;

b) calculating the average channel condition of the channels for which channel conditions are received;

c) for each user, determining a ratio of the most recently received indication of the channel condition with respect to the average channel condition; and

d) transmitting over the channel associated with the highest ratio.

3. A method for determining to which users, from among a plurality of users, access to a communication system is to be provided, such access being provided at any one time to a group of users that includes less than all of the plurality of users, such access being provided to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the users and providing communication between the associated user and a common transmitting station, the method comprising the steps of:

a) receiving an indication of an instantaneous channel condition of at least one of the several channels;

b) computing a filter output value for each channel for which the indication of the instantaneous channel conditions are received, the filter output value being a function of the received instantaneous channel conditions;

c) calculating an access metric associated with each channel for which indications are received; and

d) granting access to the communication system to the group of users associated with the best access metric.

4. The method of claim 3, wherein, for each channel for which indications are received, the access metric is a function of the filter output value and the instantaneous channel condition of the channel.

5. The method of claim 3, wherein the step of computing the filter output value includes adding, for a particular channel, each received indication of the instantaneous channel condition and dividing by the total number of indications.

6. The method of claim 5, wherein the step of calculating the filter output value further includes combining each newly received indication to a current filter output value using a low pass filter function.

7. The method of claim 6, wherein the step of calculating the filter output value further includes selecting a time-constant for the low pass filter.

8. The method of claim 3, wherein the group of users includes only one user.

9. The method of claim 3, wherein only one channel exists between the common transmitting station and any one user.

11. The method of claim 3, wherein the indication of an instantaneous channel condition is a data rate control message.

12. The method of claim 7, wherein the filter output value for the k^th channel is calculated using the following equation:

13. The method of claim 12, wherein if the most recent access metric calculated for the k^th channel is not less than the most recent access metric calculated all of the other channels than the filter output value is calculated using the following equation:

14. The method of claim 12, wherein the filter output value is initialized to a predetermined value.

15. The method of claim 14, wherein the predetermined value is equal to a minimum value for the channel condition divided by the number of users.

16. A method for determining to which users, from among a plurality of users, access to a communication system is to be provided, such access being provided at any one time to a group of users that includes less than all of the plurality of users, such access being provided to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the users and providing communication between the associated user and a common transmitting station, the method comprising the steps of:

a) determining an instantaneous channel condition of at least one of the several channels;

b) computing an average throughput value for at least some of the channels for which the instantaneous channel conditions are determined;

c) calculating an access metric associated with each channel for which the instantaneous channel conditions are determined; and

d) granting access to the communication system to the group of users associated with the best access metric.

17. The method of claim 16, wherein the instantaneous channel condition is determined based upon the carrier-to-interference ratio of the channel.

18. The method of claim 16, wherein the average throughput is determined based upon a data rate at which data was transmitted in previous frames.

19. The method of claim 16, wherein at least some of the users are available bit rate users, and wherein the instantaneous channel conditions are determined for only those available bit rate users in order to determine which of the available bit rate users are to be granted access.

20. A method for granting access to a code division multiple access communication system, including the steps of:

a) providing access to as many constant bit rate users and variable bit rate users as possible;

b) determining a channel condition for each channel between a common transmitting station and each of a plurality of available bit rate users attempting to gain access to the communication system;

c) determining a throughput value associated with each of the channels between the common transmission station and each of the plurality of available bit rate users;

d) determining an access metric associated with each of the channels between the common transmission station and each of the plurality of available bit rate users; and

e) if all constant bit rate users and all variable bit rate users have been granted access, then granting access to those available bit rate users associated with the best access metrics.

21. A transmitting station for transmitting to selected users from among a plurality of users, such selected users including less than all of the plurality of users, such transmission being performed to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the selected users, including:

a) a first processor for determining for each channel, a value representing the amount of data transmitted on the channel over a predetermined amount of time;

b) a receiver that receives a value representing the highest data rate at which each channel can currently receive data;

c) a second processor that determines for each channel, a ratio of the received value representing the highest data rate, with respect to the value representing the amount of data transmitted and selects at least one user associated with the channels having the highest ratios; and

d) a transmitter, coupled to the second processor, that transmits over the channels associated with the highest ratios to the selected users.

22. The transmitter of claim 21, wherein the transmitter transmits to only the best user over the channel associated with the highest ratio.

31. The transmitter of claim 21, wherein the indication of an instantaneous channel condition is an indication of the rate at which the user can receive transmissions from the common transmitting station.

32. The transmitter of claim 21, wherein the indication of an instantaneous channel condition is a data rate control message.

35. The transmitter of claim 32, wherein the filter is initialized to a predetermined value.

23. A transmitting station for transmitting to selected users from among a plurality of users, such selected users including less than all of the plurality of users, such transmission being performed to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the selected users, including:

a) a first processor that determines a channel condition of a channel associated with each user;

b) a second processor that calculates the average channel condition of the channels for which channel conditions are determined;

c) a third processor, coupled to the first and second processors, that, for each user, determines a ratio of the most recently received indication of the channel condition with respect to the average channel condition; and

d) a transmitter, coupled to the third processor, that transmits over the channel associated with the highest ratio in response to the third processor.

24. A transmitting station for transmitting to selected users from among a plurality of users, such selected users including less than all of the plurality of users, such transmission being performed to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the selected users, including:

a) a first processor that determines an indication of an instantaneous channel condition of at least one of several channels;

b) a filter, coupled to the first processor, that computes a filter output value for each channel for which the indication of the instantaneous channel conditions are received, the filter output value being a function of the received instantaneous channel conditions; and

c) a second processor, coupled to the first processor and the filter, that calculates an access metric associated with each channel for which indications are received and selects the group of users associated with the best access metric.

25. The transmitter of claim 24, wherein, for each channel for which indications are received, the access metric is a function of the filter output value and the instantaneous channel condition of the channel.

26. The transmitter of claim 24, wherein the filter adds, for a particular channel, each received indication of the instantaneous channel condition and divides by the total number of indications.

27. The transmitter of claim 26, wherein the filter combines each newly received indication to a current filter output value using a low pass filter function.

28. The transmitter of claim 27, wherein the filter selects a time-constant for the low pass filter.

29. The transmitter of claim 24, wherein the group of users includes only one user.

30. The transmitter of claim 24, wherein only one channel exists between the transmitter and any one user.

33. The transmitter of claim 28, wherein the filter calculates an output value for a k^th channel using the following equation:

34. The transmitter of claim 33, wherein if the most recent access metric calculated for the k^th channel is not less than the most recent access metric calculated all of the other channels than the filter output value is calculated using the following equation:

36. The transmitter of claim 34, wherein the predetermined value is equal to a minimum value for the channel condition divided by the number of users.

37. A transmitting station for transmitting to selected users from among a plurality of users, such selected users including less than all of the plurality of users, such transmission being made to the plurality of users over a plurality of channels, each of the plurality of channels being associated with one of the selected users, including:

a) a first processor that determines an instantaneous channel condition of at least one of the several channels;

b) a second processor coupled to the first processor, that computes an average throughput value for at least some of the channels for which the instantaneous channel conditions are determined; and

c) a third processor, coupled to the first and second processor, that calculates an access metric associated with each channel for which the instantaneous channel conditions are determined and grants access to the communication system to the group of users associated with the best access metrics.

38. The transmitter of claim 37, wherein the instantaneous channel condition is determined based upon the carrier-to-interference ratio of the channel.

39. The transmitter of claim 37, wherein the average throughput is determined based upon a data rate at which data was transmitted in at least one previous frame.

40. The transmitter of claim 37, wherein at least some of the users are available bit rate users, and wherein the instantaneous channel conditions are determined for only those available bit rate users in order to determine which of the available bit rate users are to be granted access.

43. The transmitter of claim 39, wherein the processor selects all constant bit rate (CBR) users and all variable bit rate (CBR) users before selecting any available bit rate (ABR) users.

41. A transmitter for transmitting to a code division multiple access communication system, including:

a) a processor that;

i) determines a channel condition for each channel between the transmitter and each of a plurality of users attempting to gain access to the transmitter;

ii) determines a throughput value associated with each of the channels between the common transmission station and each of the plurality of users;

iii) determines an access metric associated with each of the channels between the common transmission station and each of the plurality of users; and

iv) grants access to those users associated with the best access metrics.

42. The transmitter of claim 41, further including:

a) a receiver, coupled to the processor, that receives an indication as to whether data transmitted to user has been successfully received by the user;

wherein the processor is coupled to the receiver and adjusts the throughput value associated with a user to which data was sent but not received in response to the receiver receiving the indication.

44. The transmitter of claim 41, wherein access metrics are only calculated for ABR users.

45. A method for transmitting from a transmitting station to a receiver in a code division multiple access communication system, including:

a) transmitting to as many constant bit rate users and variable bit rate users as can be supported;

b) determining a channel condition for each channel between the transmitter and each of a plurality of available bit rate users attempting to gain access to the transmitter;

c) determining a throughput value associated with each of the channels between the common transmission station and each of the plurality of available bit rate users;

d) determining an access metric associated with each of the channels between the common transmission station and each of the plurality of available bit rate users; and

e) if all constant bit rate users and all variable bit rate users have been granted access, then granting access to those available bit rate users associated with the best access metrics.

46. The method of claim 45, further including:

a) receiving an indication as to whether data transmitted to user has been successfully received by the user;

b) adjusting the throughput value associated with a user to which data was sent, but not received, in response to the receiver receiving the indication.