Transmission channel bandwidth selection for communications between multi-bandwidth nodes

1. A method of dynamically selecting one of a default channel bandwidth and an alternate channel bandwidth for transmitting information over a wireless communication link which couples a transmitter node, designed to transmit at the default channel bandwidth and the alternate channel bandwidth, to a receiver node, designed to receive at the default channel bandwidth and the alternate channel bandwidth, the method comprising:

transmitting, from the transmitter node to the receiver node, a request message at the default channel bandwidth comprising a requested channel bandwidth which the transmitter node requests to use for transmitting the information to the receiver node, wherein the requested channel bandwidth comprises one of the default channel bandwidth and the alternate channel bandwidth;

changing a transmission bandwidth at which the transmitter node is transmitting from the default channel bandwidth to the requested channel bandwidth within a first Short InterFrame Spacing period when the requested channel bandwidth is different from the default channel bandwidth after the transmitter node transmits the request message;

transmitting, from the receiver node to the transmitter node responsive to the request message, a response message at the default channel bandwidth comprising an acknowledgement indicator when the channel bandwidth requested by the transmitter node is available to transmit the information to the receiver node;

transmitting, from the receiver node to the transmitter node responsive to the request message, a response message at the default channel bandwidth comprising a denial indicator when the channel bandwidth requested by the transmitter node is not available to transmit the information to the receiver node; and

changing the transmission bandwidth at which the transmitter node is transmitting from the requested channel bandwidth to the default channel bandwidth within a second Short InterFrame Spacing period when the denial indicator is received at the transmitter node.

2. A method according to claim 1 , further comprising:

transmitting a capability message from the transmitter node and the receiver node to other nodes, wherein the capability message comprises a multi-channel bandwidth information element (IE) which indicates that the transmitter node and the receiver node are designed to transmit/receive at either of the default channel bandwidth and the alternate channel bandwidth.

3. A method according to claim 1 , wherein the request message further comprises:

a transmitter address field comprising a transmitter identifier unique to the transmitter node; and

a receiver address field comprising a receiver identifier unique to the receiver node, wherein the transmitter and receiver identifiers are used to indicate a particular channel bandwidth being requested by the transmitter node.

4. A method according to claim 3 , wherein the request message further comprises a frame control field used to indicate that the request message is a control frame, that the type of control message is the request message, and a particular channel bandwidth being requested by the transmitter node.

5. A method according to claim 1 , wherein the response message further comprises:

a receiver address field comprising a receiver identifier unique to the receiver node, the receiver identifier comprising the acknowledgement or denial indicator.

6. A method according to claim 5 , wherein the response message further comprises a frame control field used to indicate that the response message is a control frame, that the type of control message is the response message, and the acknowledgement or denial indicator.

7. A method according to claim 1 , wherein the request message further comprises:

a frame control field used to indicate that the request message is a control frame, that the type of control message is the request message, and a particular channel bandwidth being requested by the transmitter node.

8. A method according to claim 7 , wherein the frame control field comprises a type field of first bits indicating that the request message is the control frame and a sub-type field of second bits different from the first bits and indicating that the type of control message is the request message and the particular channel bandwidth being requested by the transmitter node, and the frame control field follows a standard protocol in which the second bits have a number of assigned states smaller than the number of states able to be taken by the second bits, the method further comprising using unassigned states of the second bits according to the standard protocol to indicate that the type of control message is the request message and the particular channel bandwidth is different from the default bandwidth.

9. A method according to claim 8 , wherein states of a particular sub-type field of a particular transmission indicate whether the particular transmission is a request-to-send message, a clear-to-send message, or an acknowledgement message.

10. A method according to claim 1 , wherein the response message further comprises:

a frame control field used to indicate that the response message is a control frame, that the type of control message is the response message, and the acknowledgement or denial indicator.

11. A method according to claim 1 , wherein the alternate channel bandwidth comprises at least one of a higher channel bandwidth and a lower channel bandwidth, and further comprising:

determining quality of the communication link at the transmitter node;

selecting the requested channel bandwidth based on the quality of the communication link determined at the transmitter node, wherein the requested channel bandwidth comprises the highest channel bandwidth that is supported based on the quality of the communication link determined at the transmitter node; and

generating the request message to specify the selected one of the default, higher and lower channel bandwidths.

12. A method according to claim 11 , wherein the alternate channel bandwidth comprises at least one of a higher channel bandwidth and a lower channel bandwidth, and further comprising:

determining quality of the communication link at the receiver node;

determining whether the requested channel bandwidth requested by the transmitter node is supported based on the quality of the communication link determined at the receiver node; and

generating the response message, based on the quality of the communication link determined at the receiver node, to indicate whether the quality of the communication link determined at the receiver node supports the requested channel bandwidth, wherein the response message specifies the highest one of the default, higher and lower channel bandwidths that is supported by the quality of the communication link determined at the receiver node.

13. A method according to claim 1 , wherein the request message is a request-to-send message and the response message is a clear-to-send message.

14. A method according to claim 1 , further comprising permitting the transmitter to change the requested channel bandwidth in successive frames.

15. A method according to claim 1 , further comprising maintaining, at the transmitter node, the transmission bandwidth at the alternate channel bandwidth when the acknowledgment indicator is received at the transmitter node even if a subsequent data transaction fails.

16. A method according to claim 1 , further comprising altering a duration of a Short InterFrame Spacing period between transmissions between the transmitter node and the receiver node after the response message has been received when the acknowledgement indicator is transmitted and the transmission bandwidth is the alternate channel bandwidth.

17. A method of dynamically selecting a transmission bandwidth for transmitting information over a wireless communication link between a transmitter and a receiver, the method comprising:

transmitting a request-to-send (RTS) message from the transmitter to the receiver at a default channel bandwidth, the RTS message including:

a control field having a type field indicating that the RTS message is a control frame and a sub-type field indicating that the type of control message is the RTS message, and

transmitter and receiver address fields respectively having a transmitter and receiver identifier unique to the transmitter and receiver,

at least one of the sub-type field or a combination of the transmitter and receiver identifiers containing a requested bandwidth which the transmitter requests to use for transmitting the information to the receiver, wherein the requested bandwidth comprises one of the default channel bandwidth and an alternate channel bandwidth; changing a transmission bandwidth at which the transmitter is transmitting from the default channel bandwidth to the requested bandwidth within a first Short InterFrame Spacing period when the requested bandwidth is different from the default channel bandwidth after the transmitter transmits the RTS message;

transmitting a clear-to-send (CTS) message from the receiver to the transmitter at the default bandwidth, the CTS message responsive to the RTS message and containing:

a frame control field having a type field indicating that the CTS message is a control frame and a sub-type field indicating that the type of control message is the CTS message, and

a receiver address field having a receiver identifier unique to the receiver, at least one of the sub-type field or the receiver identifier including an acknowledgement or denial indicator respectively confirming or denying use by the transmitter of the requested bandwidth, and

changing the transmission bandwidth at which the transmitter is transmitting from the requested bandwidth to the default channel bandwidth within a second Short InterFrame Spacing period when the denial indicator is received at the transmitter.

18. A method according to claim 17 , wherein both the sub-type field and the transmitter and receiver identifiers contain the requested bandwidth.

19. A method according to claim 17 , wherein both the sub-type field and the receiver identifier contain the acknowledgement or denial indicator.

20. A method according to claim 17 , wherein the frame control field of each of the RTS and CTS messages follows a standard protocol it which the sub-type field has a number of assigned states smaller than the number of states able to be taken, the method further comprising using unassigned states according to the standard protocol to indicate the type of control message and that the requested bandwidth is different from the default channel bandwidth.

21. A method according to claim 17 , further comprising altering a duration of a Short InterFrame Spacing period between transmissions between the transmitter and the receiver after the CTS message has been received when the acknowledgement indicator is transmitted and the requested bandwidth different from the default channel bandwidth.