Base station and communication device can handover between two base stations

A first base station (BS), comprising:

• at least one storage device, configured to store program codes;
• a first communication interfacing device, configured to transmit signals or to receive signals with at least one BS;
• a second communication interfacing device, configured to transmit signals or to receive signals with a plurality of user equipments;
• at least one processing circuit, coupled to the at least one storage device and the first and second communication interfacing devices, configured to execute the program codes comprising following steps:
• (a) controlling the second communication interfacing device to receive a first Packet Data Convergence Protocol Service Data Unit (PDCP SDU) from a first user equipment, wherein the first PDCP PDU comprises a first PDCP SDU and a first PDCP Sequence Number (SN), the first PDCP SN is associated to the first PDCP SDU, and the first PDCP SDU comprises a flow identity (ID) and an Internet Protocol (IP) packet;
• (b) initiating a handover for the first user equipment with a second BS;
• and
• (c) when the first PDCP PDU is received, controlling the first communication interfacing device to forward the IP packet but not to forward the flow ID, to the second BS in response to the handover;
• wherein associating the first PDCP SDU to the first PDCP SN enables handover to be performed without forwarding the flow ID.

A user equipment capable of communicating with a first base station (BS) and a second BS, comprising:

• a storage device, configured to store program codes;
• a communication interfacing device, configured to transmit signals or to receive signals;
• a processing circuit, coupled to the storage device and the communication interfacing device, configured to execute the program codes comprising following steps:
• (a) associating a first Packet Data Convergence Protocol Service Data Unit (PDCP SDU) to a first PDCP Sequence Number (SN), wherein the first PDCP SDU comprises a flow identity (ID) and an Internet Protocol (IP) packet;
• (b) controlling the communication interfacing unit to receive a handover command to hand over from the first BS to the second BS;
• and
• (c) when the first PDCP SDU is associated to the first PDCP SN, controlling the communication interfacing device to transmit a first PDCP PDU to the second BS when handing over to the second BS according to the handover command, wherein the first PDCP PDU comprises the IP packet but does not comprise the flow ID;
• wherein associating the first PDCP SDU to the first PDCP SN enables handover to be performed without forwarding the flow ID.