Methods and apparatus for clear channel assessment

An apparatus in a wireless communications system including a first primary channel having a first frequency spectrum bandwidth and a second primary channel having a second frequency spectrum bandwidth, wherein the second frequency spectrum bandwidth includes the first frequency spectrum bandwidth, and secondary channels are associated with the second primary channel but not with the first primary channel comprising:

• a processor configured to:
• determine whether to transmit a wireless message over the first primary channel based on a property of the wireless message;
• in response to determining the wireless message is transmitted over the first primary channel:
• determine whether the first primary channel is idle based, at least in part, on whether a preamble is detected on the second primary channel,
• perform a first back-off procedure based on the determination;
• in response to determining the wireless message is transmitted over a channel different than the first primary channel;
• second determine whether the second primary channel is idle based, at least in part, on whether a preamble is detected on the first primary channel,
• perform a second back-off procedure based on the second determination, and
• determine whether one or more of the secondary channels associated with the second primary channel are idle for a PCT Inter-frame Space (PIFS) time period before a transmission of the wireless message;
• a transmitter configured to:
• transmit the wireless message over the first primary channel is response to completion of the first back-off procedure, wherein the transmission is restricted to the first frequency spectrum, and
• transmit the wireless message over the second primary channel and the determined idle secondary channels in response to completion of the second back-off procedure.

An apparatus in a wireless communications system including a first primary channel having a first frequency spectrum and a second primary channel having a second frequency spectrum, wherein the second frequency spectrum bandwidth includes the first frequency spectrum and secondary channels are associated with the second primary channel but not with the first primary channel, comprising:

• means for determining whether to transmit a wireless message over the first primary channel based on a property of the wireless message;
• means for determining whether the first primary channel is idle based, at least in part, on whether a preamble is detected on the second primary channel;
• means for performing a first back-off procedure based on whether the first primary channel is idle in response to the means for determining the wireless message is to be transmitted over the first primary channel;
• means for determining whether the second primary channel is idle based, at least in part, on whether a preamble is detected on the first primary channel;
• means for performing a second back-off procedure based on whether the second primary channel is idle in response to the means for determining the wireless message is to be transmitted over a channel different than the first primary channel;
• means for determining whether one or more of the secondary channels associated with the second primary channel are idle for a PCT Inter-frame Space (PIFS) time period before a transmission of the wireless message over the second primary channel;
• means for transmitting the wireless message over the first primary channel based on a completion of the first back-off procedure, wherein the transmission is restricted to the first frequency spectrum;
• and
• means for transmitting the wireless message over the second primary channel and the determined idle secondary channels based on a completion of the second back-off procedure in response to the means for determining that the wireless message is to be transmitted over at least the second primary channel.

A non-transitory computer readable storage medium comprising instructions that when executed cause a processor to perform a method in a wireless communications system including a first primary channel having a first frequency spectrum and a second primary channel having a second frequency spectrum, wherein the second frequency spectrum includes the first frequency spectrum bandwidth, and secondary channels are associated with the second primary channel but not with the first primary channel, the method comprising:

• determining whether to transmit a wireless message over the first primary channel based on a property of the wireless message;
• in response to determining the wireless message is to be transmitted over the first primary channel:
• determining whether the first primary channel is idle based, at least in part, on whether a preamble is detected on the second primary channel,
• performing a first back-off procedure based on whether the determination, and
• transmitting the wireless message over the first primary channel based on a completion of the first back-off procedure, wherein the transmission is restricted to the first frequency spectrum, and
• in response to determining the wireless message is to be transmitted over a channel different than the first primary channel;
• second determining whether the second primary channel is idle based, at least in part, on whether a preamble is detected on the first primary channel;
• performing a second back-off procedure based on the second determination,
• determining whether one or more of the secondary channels associated with the second primary channel are idle for a PCT Inter-frame Space (PIFS) time period before a transmission of the wireless message, and
• transmitting the wireless message over the second primary channel and the determined idle secondary channels based on a completion of the second back-off procedure.