1. A transmission method performed by a device and comprising:transmitting, by the device, a cellular uplink signal and a proximity service (ProSe) signal based on a total transmission power PCMAX,
wherein the total transmission power PCMAX satisfies PCMAX_L?PCMAX?PCMAX_H,
where PCMAX_L is a lower bound and PCMAX_H is an upper bound,
wherein, based on (i) that the cellular uplink signal is transmitted on subframe n, (ii) that the ProSe signal is transmitted on subframe m, and (iii) that the subframe n is asynchronous with the subframe m, the subframe n is taken as a reference,
wherein based on (iv) that the transmission of the uplink signal leads the transmission of the ProSe signal, the upper bound PCMAX_H is determined in consideration of subframe pairs of (n, m) and (n, m?1).