Granted Patent B1

US 7,940,688 · App. 11/748,259 · Granted May 10, 2011

Abstract

Claims (30)

1. A method of providing collision avoidance and channel capture avoidance in a multi-channel Common Control Channel (CCC) environment, the method comprising:

maintaining at a node a timer comprising a Network Allocation Vector (NAV) for each channel which, if set, prevents the node from transmitting on the channel:

determining at a node whether a transmission reservation response, comprising a Common Control-Clear To Send (CC-CTS) with reservation duration of non-zero value, is pending and how many CC-CTSs are pending for each channel;

determining whether said node is a destination of a pending transmission request comprising a Common Control-Request To Send (CC-RTS);

sending, by a node that sent a CC-CTS in response to receiving a CC-RTS, notification that the CC-RTS is cancelled when a channel used by the node is idle for a predetermined period of time;

resetting said NAV for a channel when the channel is idle for a predetermined period of time and when there are no pending CC-CTSs; and

refraining from resetting said NAV when there are pending CC-CTSs.

2. The method of claim 1 wherein said determining at a node whether a CC-CTS is pending and how many CTSs are pending comprises:

incrementing a counter for a channel when a new CC-CTS arrives with non-zero Duration field for the channel;

decrementing said counter for a channel when notice is received of the cancellation of a reservation for the channel; and

clearing said counter when a NAV for the channel expires.

3. The method of claim 2 wherein said determining whether said node is a destination of a pending RTS comprises:

setting a flag when a node is the destination of a CC-RTS requesting channel;

clearing said flag when a Transmit Opportunity (TXOP) cancellation request is sent; and

clearing said flag when said NAV expires.

4. A non-transitory computer readable medium having computer executable instructions thereon for providing collision avoidance and channel capture avoidance in a multi-channel CCC environment, the medium comprising:

instructions for maintaining at a node a timer comprising a Network Allocation Vector (NAV) for each channel which, if set, prevents the node from transmitting on the channel:

instructions for determining at a node whether a transmission reservation response, comprising a Common Control-Clear To Send (CC-CTS) with reservation duration of non-zero value, is pending and how many CC-CTSs are pending for each channel;

instructions for determining whether said node is a destination of a pending transmission request comprising a Common Control-Request To Send (CC-RTS);

instructions for sending, by a node that sent a CC-CTS in response to receiving a CC-RTS, notification that the CC-RTS is cancelled when a channel used by the node is idle for a predetermined period of time;

instructions for resetting said NAV for a channel when the channel is idle for a predetermined period of time and when there are no pending CC-CTSs; and

instructions for refraining from resetting said NAV when there are pending CC-CTSs.

5. The computer readable medium of claim 4 wherein said instructions for determining at a node whether a CC-CTS is pending and how many CTSs are pending comprises:

instructions for incrementing a counter for a channel when a new CC-CTS arrives with non-zero Duration field for the channel;

instructions for decrementing said counter for a channel when notice is received of the cancellation of a reservation for the channel; and

instructions for clearing said counter when a NAV for the channel expires.

6. The computer readable medium of claim 5 wherein said instructions for determining whether said node is a destination of a pending Request To Send (RTS) comprises:

instructions for setting a flag when a node is the destination of a CC-RTS requesting channel;

instructions for clearing said flag when a Transmit Opportunity (TXOP) cancellation request is sent; and

instructions for clearing said flag when said NAV expires.

Assignments (23)