Patent ID: 7295575

Claim:
A packet transmitting apparatus, comprising: a context identifier (CID) selection section that sets a plurality of contexts to one data stream; a header compression section that compresses a sequence number on a per context basis, said sequence number denoting the order of packets and said context identifying a data stream; a transmission section that on a per packet basis transmits the sequence number compressed on a per context basis with data; and an sequence number (SN) examination section that compares a sequence number in a packet that is to be transmitted, with a sequence number in an immediately preceding packet, and wherein: said CID selection section, provided that the difference between the sequence number in the packet that is to be transmitted and the sequence number in the immediately preceding packet exceeds a predetermined range, selects a context identifying number that differs from the context identifying number in the immediately preceding packet, and said header compression section compresses a sequence number on a per context identifying number basis.