Method for assigning optimal packet lengths in a variable rate communication system

• US 6,064,678 A
• Filed: 11/07/1997
• Issued: 05/16/2000
• Est. Priority Date: 11/07/1997
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Padovani, Roberto, Sindhushayana, Nagabhushana T.
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US08/965,705
• Time in Patent Office: 921 Days
• Field of Search: 370/470, 370/320, 370/328, 370/329, 370/335, 370/338, 370/342, 370/349, 370/350, 370/441, 370/332, 370/333, 370/336, 455/522, 455/466, 455/510, 455/450, 455/464, 455/9, 455/11.1, 455/507, 455/509, 455/511, 455/515, 455/525, 455/550, 455/560, 455/561, 455/95, 455/103, 375/200, 375/203, 375/225, 375/246
• US Class Current: 370/470
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/0018 based on latency requirement
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters

Abstract

A method for assigning optimal packet lengths in a variable rate communication system capable of data transmission at one of a plurality of data rates. The packet lengths for the data rates are selected such that the maximum throughput rate is achieved while conforming to a fairness criteria. The fairness criteria can be achieved by restricting the packet length assigned to each data rate to a range of value, or L_i^min ≦L_i ≦L_i^max. The packet lengths for all data rates are first initialized to the maximum packet lengths for those data rates. Then, for each data rate, a determination is made whether another packet length assignment would result in improved throughput rate. If the answer is yes, the packet length for this data rate is reassigned and the throughput rate with the updated packet length assignments is recomputed. The process is repeated for each data rate until all data rates have been considered. The throughput rate can be calculated using a probabilistic model or a deterministic model.

Claims

1. A method for assigning packet lengths in a variable rate communication system comprising the steps of:

selecting a fairness criteria;

assigning each of a plurality of data rates in said communication system to an initial packet length assignment;

computing a throughput rate based on said initial packet length assignment;

reassigning packet lengths for selected data rates in conformance with said fairness criteria if said reassignments result in higher throughput rate.

2. The method of claim 1 wherein said selecting step comprises the step of:

selecting a minimum packet length and a maximum packet length for each of said plurality of data rates.

3. The method of claim 2 wherein said maximum packet length is twice said minimum packet length for each of said plurality of data rates.

4. The method of claim 2 wherein said minimum packet length and said maximum packet length are identical for all data rates.

5. The method of claim 4 wherein said maximum packet length is twice said minimum packet length for all data rates.

6. The method of claim 1 wherein said fairness criteria is based on a set of fairness factors.

7. The method of claim 1 wherein said fairness criteria is based on an expected delay for a lowest data rate and an expected delay for a highest data rate.

8. The method of claim 1 wherein said computing step is based on a probabilistic model.

9. The method of claim 1 wherein said computing step is based on a deterministic model.

10. The method of claim 1 wherein said initial packet length assignment comprises setting said packet length of each of said plurality of data rates to a maximum packet length for said data rate.

11. The method of claim 1 wherein said reassigning step comprises the steps of:

selecting a data rate from said plurality of data rates;

comparing said selected data rate against a most recently computed throughput rate;

setting a packet length of said selected data rate to a minimum packet length for said selected data rate if said selected data rate is lower than said most recently computed throughput rate;

recomputing said throughput rate after said setting step; and

repeating said selecting, comparing, setting, and recomputing steps for all data rates in said plurality of data rates.

12. The method of claim 1 wherein said reassigning step comprises the steps of:

selecting a data rate from said plurality of data rates;

comparing said selected data rate against a most recently computed throughput rate;

setting a packet length of said selected data rate to a minimum packet length for said selected data rate if said selected data rate is lower than said most recently computed throughput rate;

repeating said selecting, comparing, and setting steps for all data rates in said plurality of data rates; and

recomputing said throughput rate after said repeating step.

13. The method of claim 12 further comprising the step of:

ordering said plurality of data rates in an order of increasing data rates, said ording step interposed between said selecting step and said assigning step.

14. The method of claim 1 wherein said communication system comprises more than two data rates.

15. The method of claim 1 said wherein communication system comprises eight or more data rates.

16. A method for assigning packet lengths in a variable rate CDMA communication system comprising the steps of:

selecting a fairness criteria;

computing a throughput rate based on an initial packet length assignment for each of a plurality of data rates in said communication system;

reassigning packet lengths for selected data rates in conformance with said fairness criteria if said reassignments result in higher throughput rate.