METHOD OF CONTROLLING CONGESTION FOR CONTENTION ACCESS NETWORK

• US 20140301209A1
• Filed: 04/04/2014
• Published: 10/09/2014
• Est. Priority Date: 04/05/2013
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: GINESTE, Mathieu, GIBERT, Olivier
• Granted Patent: US 9,843,957 B2
• Time in Patent Office: Days
• US Class Current: 370/236
• CPC Class Codes: H04L 43/0888 Throughput
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04W 28/0215 based on user or device properties, e.g. MTC-capable devices services for machine-to-machine communication [M2M] or machine type communication [MTC] H04W4/70; wireless resource selection or allocation plan definition based on terminal or device properties H04W72/51
• CPC Class Codes: H04W 74/0841 with collision treatment

Abstract

A method of controlling congestion in a communications network comprising a plurality of terminals, comprises the steps of: receiving a message or a message fragment at a given instant; evaluating the number of terminals currently sending; defining a congestion window, of duration ΔTf configured so as to be proportional to the number N of terminals currently sending and inversely proportional to the maximum input loading G of the network which makes it possible to obtain a substantially zero rate of retransmissions; for each terminal and each message or message fragment to be sent, make the start of the congestion window coincide with the given instant of receipt of a message or message fragment and define an actual instant of sending of the message or message fragment as a random value taken in the congestion window.

Claims

1. A method for controlling congestion in a communications network comprising a plurality of terminals able to send a message, said method comprising:

receiving a message or a message fragment at a given instant,

evaluating the number of terminals currently operating in transmission,

defining a time interval, called a congestion window, of duration Δ

Tf configured so as to be proportional to the number N of terminals currently operating in transmission and inversely proportional to the maximum input loading G of the network which makes it possible to obtain a substantially zero rate of retransmissions, and

for each terminal and each message or message fragment to be sent, making the start of the congestion window coincide with said given instant of receipt of a message or message fragment and defining an actual instant of sending of said message or message fragment as a random value taken in the congestion window.

2. The method of controlling congestion according to claim 1, in which the duration Δ

Tf is normalized with respect to a time unit related to the duration of transmission of a message or message fragment and is taken equal to

3. The method of controlling congestion according to claim 1, in which the maximum input loading G of the network which makes it possible to obtain a substantially zero rate of retransmissions is determined analytically or by simulation by varying the input loading of the network and by comparing it with the output loading, the input loading G retained being the maximum value of the input loading for which the output loading is substantially equal to the input loading.

4. The method of controlling congestion according to claim 1, in which, for each message or message fragment to be sent, at least one redundant message or message fragment is generated, the actual instant of sending of a redundant message or message fragment being defined as a random value taken in said congestion window whose start coincides with the given instant of receipt of said message or message fragment to be sent, the input loading G of the network is replaced with the normalized input loading of the network equal to the network input loading G divided by the total number of messages or message fragments associated with a message or message fragment to be sent.

5. The method of controlling congestion according to claim 1, in which the duration Δ

Tf of the congestion window and the instant of transmission of said message are defined as integer numbers of timeslots, a timeslot having a constant duration at least equal to the duration required to transmit a message or message fragment.

6. The method of controlling congestion according to claim 1, comprising transmitting said message or message fragment to be sent or said redundant message or message fragment with a delay equal to said actual instant of transmission.

7. The method of controlling congestion according to claim 1, in which the number N of terminals currently operating in transmission is evaluated by executing the following sub-steps, for each message sent by a terminal in the form of at least one fragment:

identifying the index number or the position of the fragment sent from among the fragments belonging to said message,

if the fragment sent is the 1^st fragment of a message, incrementing by one unit the number N of terminals currently operating in transmission,

if the fragment sent is the last fragment of a message, decrementing by one unit the number N of terminals operating in transmission,

if the fragment sent is the sole fragment of a message, incrementing by one unit the number N of terminals currently operating in transmission and then decrementing, after a predetermined duration, by one unit the number N of terminals currently operating in transmission.

12. A computer program comprising instructions for the execution of the method of controlling congestion according to claim 1, when the program is executed by a processor.

13. Recording medium readable by a processor on which is recorded a program comprising instructions for the execution of the method of controlling congestion according to claim 1, when the program is executed by a processor.

8. A device for the control of congestion in a communications network comprising a plurality of terminals able to send a message, said device comprising a first module for evaluating the number of terminals currently operating in transmission and defining a time interval, called a congestion window, of duration Δ

Tf configured so as to be proportional to the number N of terminals currently operating in transmission and inversely proportional to the maximum input loading G of the network which makes it possible to obtain a substantially zero rate of retransmissions and a second module for transmitting, at a given frequency, to all the terminals of the network an item of information making it possible to deduce the duration Δ

Tf of the congestion window.

9. The device according to claim 8, in which the first module is configured for executing the following sub-steps, for each message sent by a terminal in the form of at least one fragment:

identifying the index number or the position of the fragment sent from among the fragments belonging to said message,

if the fragment sent is the 1^st fragment of a message, incrementing by one unit the number of terminals currently operating in transmission,

if the fragment sent is the last fragment of a message, decrementing by one unit the number of terminals currently operating in transmission,

if the fragment sent is the sole fragment of a message, incrementing by one unit the number of terminals currently operating in transmission and then decrementing, after a predetermined duration, by one unit the number of terminals currently operating in transmission.

10. A sender terminal able to send a message in a communications network comprising a plurality of said terminals, comprising a first module for receiving an item of information making it possible to deduce the duration Δ

Tf of a time interval, called a congestion window, within which said message can be sent, suitable second module for defining the actual instant of transmission of said message or of a fragment of said message as a random value taken in the congestion window whose start coincides with the given instant of receipt of said message and a third module to transmit said message or message fragment with a delay equal to said instant of transmission defined.

11. A communication network comprising a plurality of sender terminals according to claim 10 and at least one device for controlling congestion within said network, the device for the control of congestion in a communications network comprising a plurality of terminals able to send a message, said device comprising a first module for evaluating the number of terminals currently operating in transmission and defining a time interval, called a congestion window, of duration Δ

Tf configured so as to be proportional to the number N of terminals currently operating in transmission and inversely proportional to the maximum input loading G of the network which makes it possible to obtain a substantially zero rate of retransmissions and a second module for transmitting, at a given frequency, to all the terminals of the network an item of information making it possible to deduce the duration Δ

Tf of the congestion window.