Patent ID: 7957312

Claim:
A communication unit comprising: a transmission-time measurement section that calculates a transmission time length of a packet; a jitter measurement section that calculates an average value of jitter based on a arrival time of the packet; a packet-loss-rate measurement section that counts a sequential number of received packets and calculates a packet loss rate based on said sequential number of received packets; a relative-redundancy calculation section that calculates, based on said transmission time length, said packet loss rate, said average value of jitter and a requested reproduction signal quality, a relative redundancy which can realize a requested reproduction signal quality in a forward error correction (FEC) scheme; a retransmission-count calculation section that, in view of a characteristic of codec, calculates, based on said transmission time length, said average value of jitter, said packet loss rate and said requested reproduction signal quality, a number of times of retransmission that can realize said requested reproduction signal quality in an automatic repeat request (ARQ) scheme; an FEC-maximum-jitter measurement section that calculates, based on said calculated relative redundancy, a first estimated maximum jitter representing a maximum jitter estimated in a case of selecting said FEC scheme; an ARQ-maximum-jitter measurement section that calculates, based on said calculated number of times of retransmission, a second estimated maximum jitter representing a maximum jitter estimated in a case of selecting said ARQ scheme; and a packet control section that selects said FEC scheme if said first estimated maximum jitter is smaller than said second estimated maximum jitter, and selects said ARQ scheme if said first estimated maximum jitter is larger than said second estimated maximum jitter, and the packet control section selects between one of said FEC scheme and said ARQ scheme again if any of said transmission time length, said packet loss rate, and said average value of jitter is changed.