Wireless message scheduling for improved fairness
View Patent ↗Currently, if a wireless device transmits a message but it is not received properly, the device is required to wait a variable time before retransmitting the message, and that waiting time is increased after each unsuccessful attempt. This is to reduce network congestion at high traffic rates, but it also puts certain users at an unfair disadvantage. For example, a user that has tried repeatedly to communicate is forced to wait longer and longer intervals, while another user is permitted to communicate without delay on the same channel. Clearly, this is an unfair situation. Therefore, disclosed herein is an alternate protocol in which users are given increasing priority after each failed attempt, specifically by reducing the fixed waiting time and/or a random backoff delay, before the next attempt. Simulations show that this change substantially eliminates the unfairness.
1. A method for a wireless transmitter to transmit a message, the method comprising:
a) transmitting the message;
b) then determining that the transmitted message was not received;
c) then waiting a first delay;
d) then re-transmitting the message;
e) then determining that the re-transmitted message was not received;
f) then waiting a second delay;
g) then re-transmitting the message;
h) wherein the second delay is shorter than the first delay;
i) wherein the first delay comprises a first waiting time plus a random portion of a first contention window, the second delay comprises a second waiting time plus a random portion of a second contention window; and
j) wherein the second waiting time is shorter than the first waiting time, and the second contention window is at least equal to the first contention window.
2. The method of claim 1 , wherein the determining that the transmitted message was not received comprises failing to receive an acknowledgement within a prescribed time interval after transmitting the transmitted message.
3. The method of claim 1 , wherein the determining that the transmitted message was not received comprises receiving an indication from an intended recipient of the transmitted message that the transmitted message was corrupted.
4. The method of claim 1 , wherein the determining that the transmitted message was not received comprises receiving an indication from a base station that the transmitted message was not delivered.
5. The method of claim 1 , wherein the determining that the transmitted message was not received comprises detecting an interfering signal during or after transmitting the transmitted message.
6. The method of claim 1 , wherein the determining that the transmitted message was not received comprises receiving a negative acknowledgement from an intended recipient of the transmitted message.
7. The method of claim 1 , wherein the second delay is shorter than the first delay by a predetermined amount.
8. The method of claim 1 , wherein the second delay is shorter than the first delay by a randomly determined amount.
9. The method of claim 1 , wherein a ratio of the second delay divided by the first delay comprises a predetermined ratio.
10. A method for a user device of a wireless network comprising a base station, the method comprising:
a) transmitting a first message to the base station during a first contention-based interval;
b) then determining that the base station failed to receive the first message;
c) then waiting a first delay time selected from a first range of delay times;
d) then transmitting a second message to the base station during a second contention-based interval;
e) then determining that the base station failed to receive the second message;
f) then waiting a second delay time selected from a second range of delay times;
g) then transmitting a third message to the base station during a third contention-based interval;
h) wherein the second range of delay times is shorter than the first range of delay times;
i) wherein the first delay time comprises a first waiting time plus a random portion of a first contention window, the second delay time comprises a second waiting time plus a random portion of a second contention window; and
j) wherein the second waiting time is shorter than the first waiting time, and the second contention window is at least equal to the first contention window.
11. The method of claim 10 , wherein:
a) the first range of delay times includes a first randomly determined component;
b) the second range of delay times includes a second randomly determined component; and
c) an average of the second range of delay times is shorter than an average of the first range of delay times.
12. The method of claim 10 , further comprising:
a) after waiting the first delay time, determining that an ongoing message is being transmitted;
b) then determining that the ongoing message has ended;
c) then waiting a predetermined interval;
d) then determining that no further transmitted signals are detected during the predetermined interval; and
e) then transmitting the the second message.
13. The method of claim 10 , wherein:
a) the first range of delay times comprises a first predetermined waiting period followed by a first randomly selected waiting period; and
b) the second range of delay times comprises a second predetermined waiting period followed by a second randomly selected waiting period;
c) wherein the second predetermined waiting period is shorter than the first predetermined waiting period.
14. The method of claim 10 , wherein:
a) the first range of delay times comprises a first predetermined waiting period followed by a first contention window; and
b) the second range of delay times comprises a second predetermined waiting period followed by a second contention window;
c) wherein the second contention window is shorter than the first contention window.
15. The method of claim 10 , wherein:
a) the first range of delay times comprises a first predetermined waiting period followed by a first randomly selected waiting period within a first contention window; and
b) the second range of delay times comprises a second predetermined waiting period followed by a second randomly selected waiting period within a second contention window;
c) wherein the second contention window is shorter than the first contention window.
16. The method of claim 10 , wherein:
a) the first range of delay times comprises a first predetermined waiting period followed by a first randomly selected waiting period within a first contention window; and
b) the second range of delay times comprises a second predetermined waiting period followed by a second randomly selected waiting period within a second contention window;
c) wherein the second predetermined waiting period is shorter than the first predetermined waiting period.
17. The method of claim 16 , wherein the first predetermined waiting period is within X percent of the first contention window, wherein X is selected from the group consisting of: 15%, 10%, 5%, 2%, and 1%.
18. The method of claim 16 , wherein the second predetermined waiting period is within X percent of the second contention window, wherein X is selected from the group consisting of: 15%, 10%, 5%, 2%, and 1%.
19. The method of claim 16 , wherein the first predetermined waiting period is within X percent of the second predetermined waiting period, wherein X is selected from the group consisting of: 15%, 10%, 5%, 2%, and 1%.