randomly selecting the positions of the discovery resource elements for sending the device discovery signals;

determining the time positions and/or frequency positions of the discovery resource elements for sending the device discovery signals according to a user equipment identity; and

determining the time positions and/or frequency positions of the discovery resource element for sending the device discovery signals according to the discovery resources indicated by the configuration information;

herein the positions of the discovery resource elements for sending the device discovery signals for the first time include:

resource positions when the discovery signals are sent for the first time during a process for sending the device discovery signals; and corresponding resource positions where the device discovery signals are sent in the first discovery resource period.

The first UE 4 is further arranged to generate an initial sequence of a pseudorandom sequence according to at least one of the following parameters: a user equipment identity, a physical cell identity and a discovery resource period identity;

generate the pseudorandom sequence according to the initial sequence and a pseudorandom sequence generation manner;

generate the positions of the discovery resource elements for sending the device discovery signals according to the pseudorandom sequence and at least one of the following parameters: an index of the discovery resource period and the number of the discovery resource elements in the discovery resource period; and