Improved Voip Packet Loss Recovery Algorithm

VoIP could be combined with the traditional IP application,and supports with some new application which could integrate data and audio.Compared with traditional telephone network,it has many new advantages,and got wildly usage.In face of different network environment,real-timing and reliability are both required by VoIP technology.The factors which could affect the VoIP quality including delay,static,package loss,and jitter.However,package loss is one of the most important fact affect the VoIP service quality.Turbo code is a high performance error correction code.Turbo code has low decoding complexity,and it could get almost the optimization performance in low Signal-to-Noise environment.Turbo codes could support the reliability in data transitions,but the real-time requirement can't be satisfied.In order to improve the decoding performance,Turbo code mainly use the iterative decoding mechanism.However,too much iteration will increase the complexity and delay of decoding,which will limit the use of Turbo code in communication applications witch highly required real timing.On the other hand,as we know,interleaver only exist in Turbo code,which could randomizes the information,increase the weight of the Turbo code,in order to improve the protection capability of Turbo code.Generally,the larger the interleaver size,the better the performance is.However,the larger the interleaver size,the more the data need to be transferred in the network,and the coding and decoding will cost more time.Most VoIP packages are real timing message,too much delay will lead the dissatisfaction of the consumer.On the other hand,Turbo code is a kind of correction code,but it will not always need correction.When the network environment is good, which means the package loss rate is low,large interleaver size is not necessary. Our work is to reduce the iteration time when decoding and adaptively set the interleaver size,in order to find a most appropriate point between the performance and reliability,which could be best applied to VoIP.At last,we discussed the relationship between voice quality estimate methods and consumer experience;introduced the MOS value and PESQ estimate arithmetic,and applied this technological aforementioned into the VoIP quality evaluating in this paper.Three experiments and result are displayed.We build a package loss simulation environment;use the Turbo code motioned in this paper to do the package loss recovery;use the PESQ to evaluate the repaired voice quality.According to the result of the experiment,the advantage of the improved Turbo code is displayed.