Clear-channel assessment in 40 MHz wireless receivers

A system, comprising:

• an activity sensing module configured to
• sense radio frequency (RF) activity in a first sub-channel and a second sub-channel of a communication channel of a first wireless network, and
• generate control signals based on the RF activity sensed in at least one of the first sub-channel and the second sub-channel,
• wherein the activity sensing module includes N adjacent channel interference (ACI) filter modules, wherein the N ACI filter modules are arranged in parallel and are configured to
• receive signals from N antennas, respectively,
• filter out signals in channels adjacent to the communication channel, and
• generate N filtered signals, respectively, where N is an integer greater than 2, and
• wherein the activity sensing module is configured to generate the control signals based on the N filtered signals;
• and
• a channel identification module configured to
• process the control signals,
• determine that both of the first sub-channel and the second sub-channel are available for communication in response to the RF activity originating from a second wireless network being not present in both of the first sub-channel and the second sub-channel, and
• determine that the first sub-channel is available for communication in response to the RF activity originating from the second wireless network being present only in the second sub-channel and being less than or equal to a predetermined threshold,
• wherein the second wireless network is different than the first wireless network.