Patent ID: 8223684

Claim:
A mobile communication system, comprising: a plurality of base stations forming radio zones; a mobile terminal which performs handover as the mobile terminal moves among the radio zones; and a gateway connected to a packet communication network for relaying packet communication between the packet communication network and the mobile terminal via a base station, the gateway including: a packet buffer with a capacity large enough to store packets transmitted in a downlink in a period at least from a start to an end of a handover; a buffer processing unit for storing packets transmitted by the downlink to the mobile terminal in the packet buffer and for assigning serial identification numbers to the packets in the period at least from the start to the end of the handover, wherein the buffer processing unit begins the storing and assigning in response to the start of the handover; and a retransmission processing unit for reading a packet requested by the mobile terminal from the packet buffer to retransmit the packet to the mobile terminal, wherein the mobile terminal further includes a request processing unit for requesting retransmission of unarrived packets in the handover to the retransmission processing unit, wherein the request processing unit requests packet retransmission to the transmission processing unit to eliminate a discontinuity to the retransmission processing unit when identification numbers of the packets that have arrived at the mobile terminal are discontinuous.