According to another embodiment, the set of predefined radio resources used for the transmission of a sensing signal comprises at least one OFDM symbol in time-domain and at least a set of sub-carriers in the frequency domain. One method to transmit a sensing signal in communication system based on Orthogonal Frequency Division Multiplex (OFDM) transmission is to use a single ODFM symbol in time domain and a set of sub-carriers in the frequency domain. This has the benefit of confining the interference produced to other transmissions. Another method is to transmit a sensing signal over multiple OFDM symbols in time domain and over a set of subcarriers in frequency domain. In the related art LTE system, this is done by using one or more physical resource blocks (PRB) in time and/or frequency, each consisting of twelve subcarriers in frequency domain (i.e., 180 kHz) and a 0.5 ms slot in time domain, i.e. 6 or 7 OFDM symbols depending on the cyclic prefix. Using two consecutive PRB in time domain, a sensing signal occupies a 1 ms subframe.

According to one embodiment, the sensing signal is transmitted periodically over time according to either a fixed or adaptive duty cycling period. It is beneficial for a mobile station, when decides to transmits a sensing signal autonomously, to adapt the time interval between one sensing signal transmission and the next one based on its data traffic, QoS requirement, type of traffic etc.

Sensing Response and Sensing Control Signals Design