| With the development and popularization of the Internet technology, there are more and more mass-data distribution and broadcast services in the network. The demands for efficient and reliable digital transmission and memory system are growing. Achieving high-speed and reliable transmission with limited bandwidth becomes an important research topic. Network service like voice and video data has large quantity and different importance, moreover, data loss rate in the network is constantly changing, so the use of unequal error protection (UEP) based on rateless erasure codes becomes a better choice to achieve high-speed and reliable transmission.Fountain code is a kind of erasure code with high performance in erasure channels, and the rate may be changed according to the package loss during the transmission. LT codes are the first realization of fountain codes with simple encoding and decoding, and are the base of raptor codes. This paper focuses on the unequal error protection method based on LT codes.Firstly, this paper introduces the encoding and decoding principles of LT codes and the bit error rate (BER) performance of LT codes is simulated. Meanwhile, the And-Or tree analysis method is illustrated briefly taking the block duplication encoding method as an example. Then, form the points of BER and the data recovery rate, this paper proposed two new UEP methods based on LT codes, separately called one by one selection method based on extended window and one by one selection method based on degree. One by one selection method based on extending window, focused on BER performance, can realize unequal error protection with appropriate parameter, and the BER performance is even better than EWF (Extending Window Fountain codes) method. While one by one selection method based on degree can recover the original information with less iterations, ensuring good BER performance. It is to say, the second method achieves a higher data recovery rate with the same iterations than other methods. |
PDF Full Text Request