Medium protection in wireless local area networks
A communication device generates a first data unit that spans a first bandwidth, and transmits the first data unit during a transmit opportunity (TXOP) to at least one other communication device. The communication device subsequently determines, based on respective values of TXOP duration fields included in respective physical layer (PHY) preambles of one or more data units previously transmitted during the TXOP, whether a second bandwidth of a second data unit to be transmitted by the communication device during the TXOP can be greater than the first bandwidth of the first data unit. In response to determining that the second bandwidth of the second data unit can be greater than the first bandwidth of the first data unit, the communication device generates the second data unit to span the second bandwidth greater than the first bandwidth, and transmits the second data unit during the TXOP.
1. A method for transmitting multiple data units in a communication channel, the method comprising:
generating, at a communication device, a first data unit to be transmitted during a transmit opportunity (TXOP) obtained by the communication device, the first data unit generated to span a first bandwidth;
transmitting, by the communication device, the first data unit during the TXOP to at least one other communication device;
determining, at the communication device based on respective values of TXOP duration fields included in respective physical layer (PHY) preambles of one or more data units previously transmitted during the TXOP, whether a second bandwidth of a second data unit to be transmitted during the TXOP by the communication device can be greater than the first bandwidth of the first data unit transmitted during the TXOP by the communication device;
in response to determining that the second bandwidth of the second data unit transmitted during the TXOP can be greater than the first bandwidth of the first data unit transmitted during the TXOP, generating, at the communication device, the second data unit to span the second bandwidth greater than the first bandwidth; and
transmitting, by the communication device, the second data unit during the TXOP.
2. The method of claim 1 , wherein transmitting the second data unit comprises transmitting the second data unit after transmitting the first data unit.
3. The method of claim 1 , wherein determining that the second bandwidth of the second data unit can be greater than the first bandwidth of the first data unit includes determining that each data unit transmitted during an initial frame exchange of the TXOP included, in a signal field included in the PHY preamble of the data unit, a respective TXOP duration indication set to a duration value other than an unspecified duration value.
4. The method of claim 1 , further comprising determining the second bandwidth of the second data unit such that the second bandwidth does not exceed a bandwidth corresponding to the initial frame exchange during the TXOP.
5. The method of claim 1 , wherein generating the data unit includes
determining a value of a TXOP duration field, wherein setting the TXOP duration field to indicate an unspecified TXOP duration is not allowed unless one or both i) basic service set (BSS) color is currently disabled in a BSS in which the communication device is operating and ii) the data unit includes a power save poll (PS-poll) frame,
generating the TXOP duration field, including setting the TXOP duration field to the determined value, and
generating the data unit to include the TXOP duration field.
6. The method of claim 1 , further comprising, prior to transmitting the first data unit,
transmitting, by the communication device to the at least one other communication device, an initiating data unit that includes an initiating control frame, and
receiving, from the at least one other communication device, a responding data unit that includes a response to the initiating control frame.
7. The method of claim 6 , wherein
the communication device supports operation according to a first communication protocol and a second communication protocol that is legacy with respect to the first communication protocol, and
transmitting the initiating data unit comprises transmitting the initiating data unit using a non-legacy PHY data unit specified by the first communication protocol and not specified by the second communication protocol.
8. The method of claim 7 , wherein transmitting the initiating data unit using a non-legacy physical layer (PHY) data unit format comprises transmitting the initiation data unit using an extended range PHY data unit format that extends a range of the initiating data unit with respect to ranges of legacy data units transmitted using legacy PHY data unit formats.
9. The method of claim 6 , wherein
the communication device supports operation according to a first communication protocol and a second communication protocol that is legacy with respect to the first communication protocol, and
receiving the responding data unit comprises receiving the initiating data unit transmitted using a non-legacy PHY data unit specified by the first communication protocol and not specified by the second communication protocol.
10. The method of claim 9 , wherein receiving the responding data unit comprises receiving the initiating data unit transmitted using an extended range PHY data unit format that extends a range of the initiating data unit with respect to ranges of legacy data units transmitted using legacy PHY data unit formats.
11. A communication device, comprising
a network interface device having one or more integrated circuit (IC) devices, wherein the one or more IC devices are configured to:
generate a first data unit to be transmitted during a transmit opportunity (TXOP) obtained by the communication device, the first data unit generated to span a first bandwidth,
transmit the first data unit during the TXOP to at least one other communication device,
determine, based on respective values of TXOP duration fields included in respective physical layer (PHY) preambles of one or more data units previously transmitted during the TXOP, that a second bandwidth of a second data unit to be transmitted during the TXOP by the communication device can be greater than the first bandwidth of the first data unit transmitted during the TXOP by the communication device,
in response to determining that the second bandwidth of the second data unit transmitted during the TXOP can be greater than the first bandwidth of the first data unit transmitted during the TXOP, generate the second data unit to span the second bandwidth greater than the first bandwidth, and
transmit the second data unit during the TXOP.
12. The communication device of claim 11 , wherein the one or more IC devices are configured to transmit the second data unit after transmitting the first data unit.
13. The communication device of claim 11 , wherein the one or more IC devices are configured to determine that the second bandwidth of the second data unit can be greater than the first bandwidth of the first data unit at least by determining that each data unit transmitted during an initial frame exchange of the TXOP included, in a signal field of the PHY preamble of the data unit, a respective TXOP duration indication set to a duration value other than an unspecified duration value.
14. The communication device of claim 11 , wherein the one or more IC devices are further configured to determine the second bandwidth of the second data unit such that the second bandwidth does not exceed a bandwidth of the initial frame exchange during the TXOP.
15. The communication device of claim 11 , wherein the one or more IC devices are further configured to
determine a value of a TXOP duration field, wherein setting the TXOP duration field to indicate an unspecified TXOP duration is not allowed unless one or both i) basic service set (BSS) color is currently disabled in a BSS in which the communication device is operating and ii) the data unit includes a power save poll (PS-poll) frame,
generate the TXOP duration field, including setting the TXOP duration field to the determined value, and
generate the data unit to include the TXOP duration field.
16. The communication device of claim 11 , wherein the one or more IC devices are further configured to, prior to transmitting the first data unit,
transmit, to the at least one other communication device, an initiating data unit that includes an initiating control frame, and
receive, from the at least one other communication device, a responding data unit that includes a response to the initiating control frame.
17. The communication device of claim 16 , wherein
the communication device supports operation according to a first communication protocol and a second communication protocol that is legacy with respect to the first communication protocol, and
the one or more IC devices are configured to transmit the initiating data unit using a non-legacy PHY data unit specified by the first communication protocol and not specified by the second communication protocol.
18. The communication device of claim 17 , wherein the one or more IC devices are configured to transmit the initiation data unit using an extended range PHY data unit format that extends a range of the initiating data unit with respect to ranges of legacy data units transmitted using legacy PHY data unit formats.
19. The communication device of claim 16 , wherein
the communication device supports operation according to a first communication protocol and a second communication protocol that is legacy with respect to the first communication protocol, and
the one or more IC devices are configured to receive the initiating data unit transmitted using a non-legacy PHY data unit specified by the first communication protocol and not specified by the second communication protocol.
20. The communication device of claim 19 , wherein the one or more IC devices are configured to receive initiating data unit transmitted using an extended range PHY data unit format that extends a range of the initiating data unit with respect to ranges of legacy data units transmitted using legacy PHY data unit formats.