Packet Loss Restoration Techniques For Speech Transmission In Mobile Environment

As the mobile communication market for the increasingly emergency ofhigh-quality speech business，traditional speech theory constantly facing newchallenges．Mobile communication transmission channel is constantly changing，the wireless transmission link capacity is restricted，it’s easy to have a channelcongestion in complex terrain environment．Therefore，resulting in the reception ofa data packet error ratio is higher by several orders of magnitude．In this thesis，on the basis of existing speech coding and channel codingtheory，combined with the features of the mobile communication，we point out ananalysis to the factors of influencing communication quality and the features ofpacket loss in mobile channel，and focuses on the study of speech data lossrecovery technique．First，due to the contradiction between the constancy of redundancy of thetraditional FEC and the change ability of the mobile communication，lead to actualforward error correction system can not achieve good performance on the efficiencyand effectiveness．This thesis proposes a adaptive method that according to thenumber of packet loss adaptive adjustment of redundancy which make the effect ofthe forward error correction system will not depend on the constancy of thenetwork environment and enhanced forward error correction algorithm adapt tochangeful mobile environment．Second，due to a substantial packet lost in the mobile communication, and thetraditional fixed depth of interleave coding technology cannot completelysolve．This thesis proposes a adaptive method that according to the packet loss rateadaptive adjustment interleave depth，the reasonable interleave depth settings canconvert breaking packet loss channel to stochastic independence error channel andenhanced ability to resist packet loss．Finally，an improved method about the number of packet loss and packet lossrate is proposed．The value of predictive packet loss rate reflects the current condition of network communication，then adopt corresponding adaptive algorithmat the receiver，and through the experiment proves that packet loss recovery effectof the adaptive redundancy FEC technology and adaptive interleave technologydepth has improved by using this improved packet loss and packet loss ratecalculation method．...