According to another embodiment, the set of predefined radio resources that can be used for the transmission of any of sensing signal and a sensing control signal, and a sensing response signal is in at least one TDD and/or one FDD carrier. As an inactive access point does not transmit any system information in its downlink carrier, a mobile station cannot know a priori whether a potential inactive access point is configured for TDD or FDD operation, in which carrier, and the corresponding bandwidth configuration. This embodiment resolves this issue.

In one embodiment, the set of predefined radio resources used for transmitting any of a sensing signal, a sensing response signal, and a sensing control signal is in the middle of a TDD and/or a FDD carrier bandwidth and corresponds either to the smallest frequency bandwidth configurable in the system or to at least one resource block within the smallest frequency bandwidth configurable in the system. A benefit of this method is to assure the signalling design to be bandwidth agnostic, and the configuration to be known at both transmitter and receiver. For the related art LTE system, this corresponds to a set of time-frequency radio resources comprising the six central physical resource blocks of an uplink and/or downlink frequency carrier.

In one embodiment, a transmitter selects at least a signal sequence among a set of predefined signal sequences and at least a set of radio resources among a predefined set of radio resources for the transmission of any of sensing signal, or a sensing control signal, or a sensing response signal. Any of the physical layer signals involved in the traffic sensing procedure shall at least a signal sequence transmitted over a set of time-frequency radio resources characterizing the information transmitted and the signal itself.