Systems and methods to detect and avoid collisions in channel sense multiple access communications with multipacket reception

• US 7,965,733 B2
• Filed: 03/14/2006
• Issued: 06/21/2011
• Est. Priority Date: 03/15/2005
• Status: Active Grant

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell University
• Inventors: Chan, Douglas S., Berger, Toby
• Primary Examiner(s): Rao; Seema S
• Assistant Examiner(s): DUONG, CHRISTINE T
• Application Number:
  US11/375,853
• Publication Number:
  US 20060245448A1
• Time in Patent Office: 1,925 Days
• Field of Search: 370/229, 370/230, 370/235, 370/236, 370/236.1, 370/236.2, 370/431, 370/445, 370/447, 370/448, 370/458, 370/461, 370/462, 398/98, 398/99
• US Class Current: 370/445
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04W 74/0825 with collision detection

Abstract

Methods and systems to perform collision detection (CD) in a communication network are disclosed. Methods and systems over multipacket reception (MPR)-capable physical layers are also disclosed. In one embodiment, the method for transmitting information in a network includes the steps of initiating transmission over a communication channel, monitoring a feedback channel, modifying transmission parameters for the transmission over the communication channel (where modifying includes stopping transmission and adjusting transmission parameters), if a feedback transmission is detected while monitoring the feedback channel, a duration of the feedback transmission being smaller than duration of the transmission over the communication channel, and determining whether transmission was successful, if transmission continues after modifying transmission parameters. Other embodiments of methods for transmitting and receiving information, as well as systems that implement the methods, are also disclosed.

Claims

1. A method for transmitting information in a network, the method comprising the steps of:

initiating transmission over a communication channel;

multiple packets being transmitted simultaneously and successfully received over the communication channel;

determining, by means of a control sub-system, whether signal energy of transmissions on said communication channel exceeds a predetermined amount;

preventing transmission over said communication channel, if it has been determined, by the control sub-system, that said signal energy exceeds the predetermined amount;

monitoring a feedback channel;

transmitted feedback information originates at a receiver, said receiver receiving and decoding simultaneously transmitted multiple packets;

said transmitted feedback information conveying whether one or more of said simultaneously transmitted multiple packets can not be successfully decoded;

modifying transmission parameters for the transmission over the communication channel, if a feedback transmission is detected while monitoring the feedback channel, a duration of the feedback transmission being smaller than duration of the transmission over the communication channel;

data being received over the communication channel;

determining communication channel information from the received data;

the communication channel information comprising a status of transmissions on the communication channel; and

determining, utilizing the communication channel information, whether to transmit.

2. The method of claim 1 wherein the step of modifying transmission parameters comprises the steps of:

determining if transmission should stop; and

rescheduling transmission, if transmission is stopped.

3. The method of claim 1 further comprising the step of:

rescheduling transmission, if transmission was not successful.

10. The method of claim 1 wherein a slotted-time system is used for transmission;

and wherein the step of scheduling transmission comprises the step of ascertaining a timing of transmission in relation to a timeslot.

11. The method of claim 1 further comprising the steps of:

receiving feedback channel information; and

determining, utilizing the feedback channel information, whether to transmit.

12. The method of claim 11 further comprising the step of:

scheduling, after determining not to transmit, attempted transmission after a backoff duration interval.

13. The method of claim 11 wherein a slotted-time system is used for transmission;

and wherein the step of scheduling transmission comprises the step of ascertaining a timing of transmission in relation to a timeslot.

14. The method of claim 11 further comprising the step of:

determining transmission parameters, after determining to transmit.

15. The method of claim 1 wherein the step of determining whether to transmit comprises a step of determining whether a number of transmissions is at most equal to a predetermined number of transmissions.

31. The method of claim 1 wherein the communication channel information comprises an estimate of a number of transmissions on the communication channel.

35. The method of claim 1 further comprising the step of determining whether transmission was successful, if transmission continues after modifying transmission parameters.

36. The method of claim 1 wherein, in the step of determining whether a signal energy of transmissions over said communication channel exceeds a predetermined amount, the step comprises determining whether an estimate of a total number of users transmitting simultaneously over the communication channel is less than a predetermined number.

41. The method of claim 1 further comprising the step of delaying transmission for a backoff duration, if it has been determined, by the control sub-system, that said signal energy exceeds the predetermined amount, and allowing accessing said communication channel after said backoff duration.

42. The method of claim 41 wherein the step of scheduling transmission further comprises the step of:

scheduling, after determining not to transmit, attempted transmission after a backoff duration interval.

4. A method for receiving information over a communication channel, the method comprising the steps of:

monitoring the communication channel for transmission;

multiple packets being transmitted simultaneously over the communication channel;

determining whether at least one transmission is present in the communication channel;

determining, by means of a control sub-system in a receiver, whether signal energy of transmissions over the communication channel exceeds a predetermined amount;

initiating receipt of the at least one transmission, if at least one transmission is present in the communication channel;

multiple packets being successfully received from said at least one transmission;

a signal being transmitted, utilizing a feedback channel, the signal indicating that the communication channel is being utilized, if at least one transmission is present;

the feedback signal comprising status information for the communication channel;

whether at least some transmissions of multiple packets being transmitted simultaneously should be stopped being determined from said status information;

the feedback signal conveying whether one or more of said simultaneously transmitted multiple packets can not be successfully decoded;

determining, if the at least one transmission is not stopped, whether transmission has been completed;

at least one transmitting node being notified of outcome of determination, a duration of a notifying transmission being smaller than duration of transmission over the communication channel.

5. The method of claim 4 wherein at least one transmitting node ceases transmission based on said feedback signal.

6. The method of claim 4 wherein in notifying transmitting nodes of outcome determinations the following step is performed:

notifying, if it is determined that at least one transmission has been completed, a node transmitting the at least one transmission of completion.

7. The method of claim 4 wherein in notifying transmitting nodes of outcome determinations the following step is performed:

notifying, if it is determined that the at least one transmission should be stopped, a node transmitting the at least one transmission to stop transmitting.

8. The method of claim 4 further comprising the step of:

if all transmissions have not been stopped, providing communication channel conditions to transmitting nodes.

9. The method of claim 4 further comprising the step of:

if it is determined that all transmissions should be stopped, notifying all transmitting nodes to stop transmission.

32. The method of claim 4 wherein the status information comprises a number of terminals transmitting.

37. The method of claim 4 wherein, in the step of determining whether a signal energy of transmissions over said communication channel exceeds a predetermined amount, the step comprises determining whether an estimate of a total number of users transmitting simultaneously over the communication channel is less than a predetermined number.

40. The method of claim 37 further comprising the step of broadcasting said estimate of the number of transmissions over the communication channel.

43. The method of claim 4 wherein a duration of the feedback signal is smaller than duration of said at least one transmission over the communication channel.

16. A transmitter system comprising:

a transmitter/receiver subsystem comprising;

a transmitter/receiver portion capable of transmitting information over a communication channel and of receiving information transmitted over a feedback channel;

said transmitter/receiver subsystem be capable of accessing the communication channel and the feedback channel through a physical layer;

said transmitter/receiver subsystem capable of transmitting multiple packets simultaneously and successfully receiving multiple packets over the communication channel; and

a scheduling component capable of scheduling transmission of information over the communication channel; and

a transmitter/receiver control subsystem modifying transmission parameters for the transmission over the communication channel and of determining whether information was successfully transmitted;

said transmitter/receiver control subsystem determining whether signal energy of transmissions on said communication channel exceeds a predetermined amount, said transmitter/receiver control subsystem preventing transmission over said communication channel, if it has been determined, by the control sub-system, that said signal energy exceeds the predetermined amount;

the control subsystem determining whether to stop transmitting based on received feedback information;

received feedback information originates at a receiver receiving and decoding said substantially simultaneously transmitted multiple packets;

said received feedback information conveying whether at least one of said substantially simultaneously transmitted multiple packets, transmitted by said transmitter system, could not be successfully decoded.

17. The transmitter system of claim 16 wherein said transmitter/receiver control subsystem is also determining if transmission should stop and of rescheduling transmission, if transmission is stopped.

18. The transmitter system of claim 16 wherein said transmitter/receiver control subsystem also reschedules transmission, if transmission was not successful.

19. The transmitter system of claim 16 wherein a slotted-time system is used for transmission;

and wherein said scheduling component also ascertains a timing of transmission in relation to a timeslot;

a duration of feedback transmission over the feedback channel being at least one time slot.

20. The transmitter system of claim 16 wherein said transmitter/receiver control subsystem comprises:

at least one processor; and

at least one computer usable medium having computer readable code embodied therein, said computer readable code being capable of causing said at least one processor to;

modify transmission parameters for the transmission over the communication channel, if a feedback transmission is detected while monitoring the feedback channel;

determine whether transmission was successful, if transmission continues after modifying transmission parameters.

21. The transmitter system of claim 20 wherein said computer readable code, in causing said at least one processor to modify transmission parameters, is capable of causing said at least one processor to:

determine if transmission should stop; and

reschedule transmission, if transmission is stopped.

22. The transmitter system of claim 20 wherein said computer readable code is also capable of causing said at least one processor to:

reschedule transmission, if transmission was not successful.

23. The transmitter system of claim 20 wherein said computer readable code is also capable of causing said at least one processor to:

schedule, after determining not to transmit, attempted transmission after a backoff duration interval.

24. The transmitter system of claim 20 wherein said computer readable code is also capable of causing said at least one processor to:

determine transmission parameters, after determining to transmit.

25. The transmitter system of claim 16 wherein said scheduling component comprises:

at least one processor; and

at least one computer usable medium having computer readable code embodied there in, said computer readable code being capable of causing said at least one processor to;

receive feedback channel information;

determine, utilizing the feedback channel information, whether to transmit.

26. The transmitter system of claim 25 wherein said computer readable code is also capable of causing said at least one processor to:

schedule, after determining not to transmit, attempted transmission after a backoff duration interval.

27. The transmitter system of claim 25 wherein, in receiving feedback channel information, said computer readable code is capable of causing said at least one processor to obtain a number of transmissions present in the communications channel;

and wherein, in determining whether to transmit, said computer readable code is capable of causing said at least one processor to determine whether the number of transmissions is at most equal to a predetermined number of transmissions.

28. The transmitter system of claim 16 wherein said scheduling component comprises:

at least one processor; and

at least one computer usable medium having computer readable code embodied therein, said computer readable code being capable of causing said at least one processor to;

receive data over the communication channel;

determine, from the received data, whether the communication channel is in use;

schedule transmission, after determining the communication channel not to be in use.

33. The transmitter system of claim 20 wherein the communication channel information comprising a number of transmissions on the communication channel.

38. The transmitter system of claim 16 wherein said transmitter receiver control subsystem in determining whether a signal energy of transmissions over said communication channel exceeds a predetermined amount, determines whether an estimate of a total number of users transmitting simultaneously over the communication channel is less than a predetermined number.

44. The transmitter system of claim 16 wherein said transmitter/receiver control also delays transmission for a backoff duration, if it has been determined that said signal energy exceeds the predetermined amount;

allowing accessing said communication channel after said backoff duration.

45. The transmitter system of claim 44 wherein said scheduling component comprises:

at least one processor; and

at least one computer usable medium having computer readable code embodied therein, said computer readable code being capable of causing said at least one processor to;

receive data over the communication channel;

determine communication channel information from the received data;

the communication channel information comprising a status of transmissions on the communication channel;

determining, utilizing the communication channel information, whether to transmit.

46. The transmitter system of claim 16 wherein said transmission parameters comprise codes used for transmitting multiple packets simultaneously over the communication channel.

47. The transmitter system of claim 16 wherein a duration of feedback transmission over the feedback channel being smaller than duration of transmission over the communication channel.

29. A receiver system comprising:

a reception/transmission control subsystem determining whether transmissions over a communication channel are present, initiating receipt of transmissions, determining whether to stop any transmission, determining whether signal energy of transmissions over the communication channel exceeds a predetermined amount, and determining whether any transmissions have been completed;

a receiving/transmitting subsystem receiving transmissions and notifying, over a feedback channel, transmitting nodes of outcome determinations;

said receiving/transmitting subsystem being capable of receiving control information from said reception/transmission control subsystem and receiving determinations of transmission completion and of transmission stoppage from said reception/transmission control subsystem;

said receiving/transmitting subsystem receiving transmissions from a communication channel;

said receiving/transmitting subsystem separating and decoding multiple packets transmitted simultaneously over the communication channel; and

said receiving/transmitting subsystem also transmitting, if at least one transmission is present, a feedback signal over the feedback channel, the feedback signal comprising status information for the communication channel;

the receiver receiving information according to a protocol enabling multiple packets being transmitted simultaneously (multipacket reception) (MPR);

transmitted feedback signal conveying whether one or more of said simultaneously transmitted multiple packets can not be successfully decoded;

said outcomes determination comprising whether one or more of said simultaneously transmitted multiple packets can not be successfully decoded.

30. The receiver system of claim 29 wherein said reception/transmission control subsystem comprises:

at least one processor; and

at least one computer usable medium having computer readable code embodied there in, said computer readable code being capable of causing said at least one processor to;

determine whether at least one transmission is present in the communication channel;

initiate receipt of the at least one transmission, if at least one transmission is present in the communication channel;

determine whether at least some transmissions of multiple packets being transmitted simultaneously should be stopped;

determine whether, if the at least one transmission is not stopped, whether transmission has been completed;

notify at least one transmitting node of outcome of determination, a duration of a notifying transmission being smaller than duration of transmission over the communication channel.

34. The receiver system of claim 29 wherein the status information comprises a number of terminals transmitting.

39. The transmitter system of claim 29 wherein said reception/transmission control system in determining whether a signal energy of transmissions over said communication channel exceeds a predetermined mount, determines whether an estimate of a total number of users transmitting simultaneously over the communication channel is less than a predetermined number.

48. The receiver system of claim 29 wherein a duration of notifying transmission over the feedback channel being smaller than duration of transmission over the communication channel.