Method and apparatus for forward link rate scheduling

• US 6,335,922 B1
• Filed: 02/11/1997
• Issued: 01/01/2002
• Est. Priority Date: 02/11/1997
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tiedemann, Edward G. Jr., Jou, Yu-Cheun, Odenwalder, Joseph P., Lin, Yu-Chuan
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): HYUN, SOON D
• Application Number:
  US08/798,951
• Time in Patent Office: 1,785 Days
• Field of Search: 375/200, 370/335, 370/337, 370/342, 370/347, 370/348, 370/321, 370/330, 370/465, 370/468, 370/346, 370/311, 370/343, 370/322, 370/441, 370/442, 370/443, 370/444, 340/825.08
• US Class Current: 370/335
• CPC Class Codes: H04B 7/2659 for data rate control
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• 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 52/281 taking into account user or data type priority
• 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 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 72/1273 of downlink data flows
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/563 of the wireless resources

Abstract

In a communication system capable of variable rate transmission, scheduling of high speed data transmission improves utilization of the forward link and decreases the transmission delay in data communication. Each remote station is assigned one primary code channel for the duration of the communication with a cell. Secondary code channels of various types and transmission capabilities can be assigned by a channel scheduler for scheduled transmission of data traffic at high rates. Secondary code channels are assigned in accordance with a set of system goals, a list of parameters, and collected information on the status of the communication network. Secondary code channels can be grouped into sets of secondary code channels. Data is partitioned in data frames and transmitted over the primary and secondary code channels which have been assigned to the scheduled user.

Claims

1. A method for scheduling data transmissions on a forward link in a communication network comprising at least one cell and at least one scheduled user, and for assigning a transmission rate to said data transmissions, said forward link having an unscheduled capacity for unscheduled transmissions and a residual capacity for scheduled transmissions, the method comprising the steps of:

determining said residual forward link capacity available for each of said at least one cell;

assigning an assigned transmission rate to each of said at least one scheduled user;

sending said assigned transmission rate to said at least one scheduled user;

wherein said assigned transmission rate is based on said residual forward link capacity available for each of said at least one cell;

wherein said assigning step further comprises the step of determining an active member set for each of said at least one scheduled user, said active member set containing at least one cell in communication with said scheduled user;

wherein said assigned transmission rate is further based on said forward link capacity available for one or more of said at least one cell in said active member set.

2. The method of claim 1 wherein said determining step, said assigning step, and said sending step are repeated every K frames, wherein K is an integer greater than or equal to one.

3. The method of claim 2 further comprising the step of:

reassigning said assigned transmission rate of zero or more of said at least one scheduled user to a temporary transmission rate, wherein said temporary transmission rate is dependent on said forward link capacity available for each of said at least one cell.

4. The method of claim 3 wherein said reassigning step further comprises the steps of:

creating a temporary cell list of affected cells from said at least one cell in the communication network, said affected cells having inadequate transmit power to transmit data to said at least one scheduled user.

5. The method of claim 4 wherein said reassigning step further comprises the steps of:

creating a temporary priority list of affected scheduled users, said affected scheduled users comprising of said at least one scheduled user in the communication network.

6. The method of claim 5 wherein said reassigning step further comprises the steps of:

selecting an affected scheduled user from said temporary priority list of affected scheduled users, said selected affected scheduled user having a highest priority among said at least one scheduled user in said temporary priority list;

calculating a maximum temporary supportable transmission rate for said selected affected scheduled user by one or more of said at least one cell in said active member set of said selected affected scheduled user;

selecting a minimum transmission rate from said maximum temporary supportable transmission rates, said minimum transmission rate being defined as a maximum temporary transmission rate; and

wherein said temporary transmission rate is at or below said maximum temporary transmission rate and said assigned transmission rate.

7. The method of claim 1 wherein said assigning step further comprises the step of:

receiving a queue size for each of said least one scheduled user, said queue size determinative of an amount of data to be transmitted to each of said at least one scheduled user; and

wherein said assigned transmission rate is further based on said queue size for each of said at least one scheduled user.

8. The method of claim 7 wherein said assigning step further comprises the step of:

creating a priority list of scheduled users, said priority list containing each of said at least one scheduled user, wherein each of said least one scheduled user is assigned a priority; and

wherein said assigned transmission rate is further based on said priority of each of said at least one scheduled user.

9. A method for scheduling data transmissions on a forward link in a communication network comprising at least one cell and at least one scheduled user, said method comprising the steps of:

(a) determining a forward link capacity available for each of said at least one cell;

(b) assigning an assigned transmission rate to each of said at least one scheduled user; and

(c) sending said assigned transmission rate to said at least one scheduled user;

wherein;

(d) said assigned transmission rate is based on;

(1) said forward link capacity available for each of said at least one cell;

(2) said forward link capacity available for one or more of said at least one cell in an active member set;

(3) a queue size for each of said at least one scheduled user; and

(4) a priority of each of said at least one scheduled user;

(e) said assigning step further comprises the steps of;

(1) determining said active member set for each of said at least one scheduled user, said active member set containing at least one cell in communication with said scheduled user;

(2) receiving said queue size for each of said least one scheduled user, said queue size determinative of an amount of data to be transmitted to each of said at least one scheduled user;

(3) creating a priority list of scheduled users, said priority list containing each of said at least one scheduled user, wherein each of said least one scheduled user is assigned said priority;

(4) selecting a selected scheduled user from said priority list of scheduled users, said selected scheduled user having a highest priority among said at least one scheduled user in said priority list;

(5) calculating a maximum supportable transmission rate for said selected scheduled user by one or more of said at least one cell in said active member set of said selected scheduled user; and

(6) selecting a minimum transmission rate from said maximum supportable transmission rates, said minimum transmission rate being defined as a maximum transmission rate; and

(f) wherein said assigned transmission rate is at or below said maximum transmission rate.

10. The method of claim 9 wherein said assigning step further comprises the step of:

recommending a preferred transmission rate, said preferred transmission rate being based on said queue size of said selected scheduled user; and

wherein said assigned transmission rate is at or below said preferred transmission rate.

11. The method of claim 10 wherein said assigning step further comprises the steps of:

updating said forward link capacity available for one or more of said at least one cell in said active member set of said selected scheduled user to reflect a capacity allocated to said selected scheduled user; and

removing said selected scheduled user from said priority list.

12. A method for scheduling data transmissions on a forward link in a communication network comprising at least one cell and at least one scheduled user, said method comprising the steps of:

(a) determining a forward link capacity available for each of said at least one cell;

(b) assigning an assigned transmission rate to each of said at least one scheduled user;

(c) sending said assigned transmission rate to said at least one scheduled user; and

(d) reassigning said assigned transmission rate of zero or more of said at least one scheduled user to a temporary transmission rate,

wherein;

(e) said assigned transmission rate is based on said forward link capacity available for each of said at least one cell;

(f) said determining step, said assigning step, and said sending step are repeated every K frames, wherein K is an integer greater than or equal to one;

(g) said temporary transmission rate is dependent on said forward link capacity available for each of said at least one cell;

(h) said temporary transmission rate is at or below said maximum temporary transmission rate and said assigned transmission rate; and

(i) said reassigning step further comprises the steps of;

(1) creating a temporary cell list of affected cells from said at least one cell in the communication network, said affected cells having inadequate transmit power to transmit data to said at least one scheduled user;

(2) creating a temporary priority list of affected scheduled users, said affected scheduled users comprising of said at least one scheduled user in the communication network;

(3) selecting an affected scheduled user from said temporary priority list of affected scheduled users, said selected affected scheduled user having a highest priority among said at least one scheduled user in said temporary priority list;

(4) calculating a maximum temporary supportable transmission rate for said selected affected scheduled user by one or more of said at least one cell in said active member set of said selected affected scheduled user;

(5) selecting a minimum transmission rate from said maximum temporary supportable transmission rates, said minimum transmission rate being defined as a maximum temporary transmission rate;

(6) updating said forward link capacity available for one or more of said at least one cell in said active member set of said selected affected scheduled user to reflect a capacity allocated to said selected affected scheduled user; and

(7) removing said selected affected scheduled user from said priority list.

13. A communication system comprising:

at least one cell site transmitter, each cell site transmitter transmitting unscheduled primary traffic on at least one primary channel;

a channel scheduler that schedules secondary traffic on a set of at least one secondary channels;

wherein said channel scheduler schedules said secondary traffic in accordance with a residual forward link capacity of said at least one cell site transmitter;

wherein said channel scheduler further schedules said secondary traffic in accordance with a required total transmit power.

14. The communication system of claim 13 wherein said channel scheduler further schedules said secondary traffic in accordance with a required data rate.

15. The communication system of claim 14 wherein said channel scheduler further schedules said secondary traffic in accordance with a backoff power of said at least one cell site transmitter.

16. The communication system of claim 14 wherein said channel scheduler changes said data rate of said scheduled secondary traffic during a scheduling period.

17. The communication system of claim 13 wherein said channel scheduler reschedules said secondary traffic every K frames, where K is an integer.

18. The communication system of claim 17 wherein K is equal to one.

19. The communication system of claim 13 wherein said channel scheduler reschedules said secondary traffic upon receipt of a data request from a remote station.

20. The communication system of claim 13 wherein said channel scheduler further schedules said secondary traffic in accordance with a backoff power of said at least one cell site transmitter.

21. The communication system of claim 13 wherein said channel scheduler changes said total transmit power during a scheduling period.

22. The communication system of claim 13 wherein said channel scheduler schedules said secondary traffic on a temporarily reduced set of secondary channels in response to a change in forward link conditions.

23. The communication system of claim 22 wherein said cell site transmitter transmits a data rate indication in a same frame as said channel scheduler schedules said secondary traffic on said temporarily reduced set of secondary channels.

24. The communication system of claim 22 wherein said cell site transmitter transmits a data rate indication in a frame two frames prior to said channel scheduler scheduling said secondary traffic on said temporarily reduced set of secondary channels.

25. The communication system of claim 13 wherein said channel scheduler predicts a required transmit data rate based on a previous transmit data rate.

26. The communication system of claim 13 wherein said channel scheduler predicts a required transmit power based on a previous transmit power.

27. The communication system of claim 13 wherein said channel scheduler schedules said secondary traffic on a plurality of disjoint sets of secondary channels.

28. The communication system of claim 13 wherein said channel scheduler schedules said secondary traffic on a plurality of overlapping sets of secondary channels.

29. The communication system of claim 13 wherein said channel scheduler selects said secondary channels pseudorandomly.