FIG. 5 is a structural schematic diagram of the network side device 2 of a cellular network according to an embodiment of the present disclosure. As shown in FIG. 5, the network side device 2 of the cellular network includes:

a configuration unit 52 arranged to determine configuration information indicating discovery resources for device discovery; and

a sending unit 54 arranged to send the configuration information.

In practical applications, the configuration unit 52 may be implemented by a central processing unit (CPU), a digital signal processor (DSP) or a field programmable gate array (FPGA) in the network side device 2 of the cellular network; and

the sending unit 54 may be implemented by a transmitter in the network side device 2 of the cellular network.

There is a mapping relationship between discovery resource elements in adjacent discovery resource periods, the mapping relationship is used to determine at most one discovery resource element for sending device discovery signals in the current discovery resource period according to positions of the discovery resource elements which send the device discovery signals in the preceding discovery resource period of the current discovery resource period.

Specifically, the configuration unit is arranged to establish the mapping relationship of the discovery resource elements between the adjacent discovery resource periods;

establish mapping relationships k2=mod(floor((n1*K+k1+A)/N),K) and n2=mod(n1*K+k1+A,N); or