First, mCSN sends the registration message to
IMMS to register the T_Addr, P_Addr, (retrieved by ER) and the H_Flag of mCSN.
CWC discovers a
mCSN in IMMS. Next, let us consider the case in
which the mCSN moves from the old Edge Router (old ER) to the new Edge Router
(new ER). In this case, mCSN requires the IP handover operation. To do this,
the mCSN first detects the radio signal strength (RSS) from the old ER. As the
RSS from old ER drops below to the Threshold value (Tv), the mCSN prepares the
handover operation in advance. A Tv drops below, mCSN sends the hold message to
IMMS. The hold message is used to notify the handover state (i.e., H_Flag) of
mCNS which the mCSN is performing the handover. As the mCSN moves into in the
overlapped region of two network domains, the mCSN tries to get new temporary
IP address, i.e., T_Addr from new ER through Dynamic Host Configuration
Protocol (DHCP). Then, the mCSN sends the binding message to IMMS. Its message
includes T_Addr, P_Addr, and the H_Flag. As the IMMS receives binding message,
IMMS sends it to the CWC by referring to MMT. As the IMMS and CWC receive the
binding message, they update the T_Addr and the H_Flag in MMT and LBC. Finally,
the IMMS and CWC can retrieve the data from the mCSN in new network domain. In
this way, the CWC and the mCSN can exchange the data without packet loss during
the handover operation. The CoMP signaling messages are configured by extending
the Option Delta and payload in the CoAP message format [3].