A method for implementing synchronization between a gateway (aGW) and a number i of base stations (eNBi), comprising the steps of: at time T1, sending from the gateway (aGW) to the base stations (eNBi) a synchronization request signal; at times T2i, receiving by the base stations (eNBi) the synchronization request signal; at times T3i, sending from the base stations (eNBi) to the gateway (aGW) the synchronization response comprising the times T2i and either the times T3i or a first offset between the base stations' (eNBi) time system and a baseline time; at times T4i, receiving by the gateway (aGW) the synchronization response signals; and calculating for each one of the base stations (eNBi) a mapping relationship between the time system of the gateway (aGW) and the time system of the base station (eNBi) based on the times T1, T2i, T3i and T4i, the method characterized by the steps of: sending from the gateway (aGW) to the base stations (eNBi) information comprising the mapping relationship, calculating for each base station (eNBi) a transmission delay TDi between the gateway (aGW) and the base stations (eNBi) based on the times T1, T2i, T3i and T4i; determining the maximum transmission delay among the calculated transmission delays; specifying an expected transmitting time for data packets to be transmitted according to a waiting time larger than the maximum transmission delay; and sending from the gateway (aGW) to the base stations (eNBi) the expected transmitting time. at time T1, sending from the gateway (aGW) to the base stations (eNBi) a synchronization request signal; at times T2i, receiving by the base stations (eNBi) the synchronization request signal; at times T3i, sending from the base stations (eNBi) to the gateway (aGW) the synchronization response comprising the times T2i and either the times T3i or a first offset between the base stations' (eNBi) time system and a baseline time; at times T4i, receiving by the gateway (aGW) the synchronization response signals; and calculating for each one of the base stations (eNBi) a mapping relationship between the time system of the gateway (aGW) and the time system of the base station (eNBi) based on the times T1, T2i, T3i and T4i, the method characterized by the steps of: sending from the gateway (aGW) to the base stations (eNBi) information comprising the mapping relationship, calculating for each base station (eNBi) a transmission delay TDi between the gateway (aGW) and the base stations (eNBi) based on the times T1, T2i, T3i and T4i; determining the maximum transmission delay among the calculated transmission delays; specifying an expected transmitting time for data packets to be transmitted according to a waiting time larger than the maximum transmission delay; and sending from the gateway (aGW) to the base stations (eNBi) the expected transmitting time. sending from the gateway (aGW) to the base stations (eNBi) information comprising the mapping relationship, calculating for each base station (eNBi) a transmission delay TDi between the gateway (aGW) and the base stations (eNBi) based on the times T1, T2i, T3i and T4i; determining the maximum transmission delay among the calculated transmission delays; specifying an expected transmitting time for data packets to be transmitted according to a waiting time larger than the maximum transmission delay; and sending from the gateway (aGW) to the base stations (eNBi) the expected transmitting time.