Collision Avoidance for Wireless Networks

• US 20120155397A1
• Filed: 12/17/2010
• Published: 06/21/2012
• Est. Priority Date: 12/17/2010
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Shaffer, Shmuel, Shetty, Sandeep Jay, Vasseur, Jean-Philippe
• Granted Patent: US 8,873,526 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 45/74 Address processing for routing
• CPC Class Codes: H04L 47/286 Time to live
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 74/085 collision avoidance
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

In one embodiment, a particular node in a wireless network may receive a wireless signal, and may determine whether the wireless signal is intended for itself In response to determining that the wireless signal is intended for the particular node, the particular node may transmit a non-colliding wireless carrier sense detected alert (CSDA) signal during the received wireless signal to request that other nodes within communication distance of the particular node refrain from transmitting for a duration of the received wireless signal. In another embodiment, a node listens on a first frequency for a wireless CSDA signal regarding a second (colliding) frequency, and in response to receiving a CSDA signal, may refrain from transmitting a wireless signal on the second frequency for the particular duration, or else (if not receiving a CSDA signal), may allow transmission of a wireless signal on the second frequency, accordingly.

Claims

1. A method, comprising:

receiving a wireless signal at a particular node in a wireless network;

determining whether the wireless signal is intended for the particular node; and

in response to determining that the wireless signal is intended for the particular node, transmitting a non-colliding wireless carrier sense detected alert (CSDA) signal from the particular node while the wireless signal is being received to request that other nodes within communication distance of the particular node refrain from transmitting for a duration of the received wireless signal.

2. The method as in claim 1, wherein transmitting comprises:

transmitting the CSDA signal as a continuous signal for the duration of the received wireless signal.

3. The method as in claim 1, wherein transmitting comprises:

transmitting the CSDA signal as a message that indicates the duration of the received wireless signal.

4. The method as in claim 3, further comprising:

including within the message a frequency of the received wireless signal to request that other nodes within communication distance of the particular node refrain from transmitting on the frequency of the received wireless signal for the duration of the received wireless signal.

5. The method as in claim 3, further comprising:

including within the message a time-to-live (TTL) value of zero to prevent the other nodes from forwarding the message.

6. The method as in claim 1, further comprising:

receiving, within the received wireless signal, an indication of the duration of the received wireless signal.

7. The method as in claim 1, wherein transmitting comprises:

transmitting the CSDA signal as;

i) a first message that requests that other nodes within communication distance of the particular node refrain from transmitting; and

ii) a second message that indicates that other nodes within communication distance of the particular node can resume transmitting.

8. The method as in claim 1, wherein the received wireless signal is received on a first frequency, and wherein transmitting comprises:

transmitting the CSDA signal on a second frequency.

9. The method as in claim 8, wherein the second frequency is orthogonal to the first frequency.

10. The method as in claim 8, wherein the second frequency is a frequency dedicated to CSDA signals in the wireless network.

11. The method as in claim 1, wherein determining whether the wireless signal is intended for the particular node comprises:

examining a header of the received wireless signal to determine whether a destination address within the header corresponds to an address of the particular node.

12. An apparatus, comprising:

one or more wireless network interfaces adapted to receive a wireless signal;

a processor coupled to the wireless network interfaces and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to;

determine whether the received wireless signal is intended for the apparatus; and

transmit, in response to the wireless signal being intended for the apparatus, a non-colliding wireless carrier sense detected alert (CSDA) signal on at least one of the wireless network interfaces while the wireless signal is being received to request that other nodes within communication distance of the apparatus refrain from transmitting for a duration of the received wireless signal.

13. The apparatus as in claim 12, wherein the CSDA signal comprises a continuous signal transmitted for the duration of the received wireless signal.

14. The apparatus as in claim 12, wherein the CSDA signal comprises a message that indicates the duration of the received wireless signal.

15. A method, comprising:

listening, on a first frequency at a wireless transmission node in a wireless network, for a wireless carrier sense detected alert (CSDA) signal that requests that receiving nodes refrain from transmitting wireless signals on a second distinct frequency for a particular duration;

in response to receiving the CSDA signal, refraining from transmitting a wireless signal on the second frequency for the particular duration; and

in response to not receiving the CSDA signal, allowing transmission of a wireless signal on the second frequency.

16. The method as in claim 15, further comprising, in response to allowing transmission:

transmitting the wireless signal from the wireless transmission node to a particular node on the second frequency;

receiving a CSDA signal at the wireless transmission node from the particular node on the first frequency;

determining that the CSDA signal is in response to the transmitted wireless signal from the wireless transmission node; and

, in response,

continuing to transmit the wireless signal from the wireless transmission node to the particular node.

17. The method as in claim 15, further comprising:

receiving, within the CSDA signal, a message that indicates the particular duration; and

, in response,

refraining from transmitting a wireless signal on the second frequency for the indicated duration.

18. The method as in claim 15, further comprising:

determining the second frequency by the wireless transmission node based on a shared frequency hopping scheme within the wireless network.

19. An apparatus, comprising:

one or more wireless network interfaces to communicated in a wireless network, the interfaces configured to receive wireless transmission on a first frequency, and transmit wirelessly on a second distinct frequency;

a processor coupled to the wireless network interfaces and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to;

listen, on the first frequency, for a wireless carrier sense detected alert (CSDA) signal that requests that receiving nodes refrain from transmitting on the second frequency for a particular duration;

refrain from transmitting a wireless signal on the second frequency for the particular duration in response to receiving a CSDA signal; and

allow transmission of a wireless signal on the second frequency in response to not receiving a CSDA signal.

20. The apparatus as in claim 19, wherein the process when executed is further operable to:

transmit the wireless signal from the wireless network interfaces on the second frequency to a particular node;

receive a CSDA signal on the wireless network interfaces from the particular node on the first frequency during transmission of the wireless signal on the second frequency;

determine that the CSDA signal is in response to the transmitted wireless signal from the apparatus; and

, in response,

continue to transmit the wireless signal from the wireless network interfaces to the particular node.