一种基于3GPP MBMS Raptor前向纠错编码的改进算法

摘要

An improved Raptor decoding algorithm of 3GPP MBMS FEC codes is presented.The improved Algorithm introduces enhanced generator and pre-coding relationships, i.e., a two-stage pre-coding algorithm using LDPC and HDPC codes.A modification in the second encoding step of the new algorithm, more efficient encoding process than that of Raptor, is applied in order to generate the encoding symbols.More over, the key change between the two FEC schemes is that the enhanced new code introduces the use of arithmetic operations on octets, i.e., the finite field GF(256) , while the standardized Raptor code operates over Galois field GF(2).Finally, several simulation results utilizing the ns-3 environment, demonstrate that the improved algorithm improves the service coverage, reduce tune-in delay and enhances multicasting reliatility.%提出了一种改进的3GPP MBMS Raptor前向纠错编码算法.新算法引入加强的发生器和预编码结构,如用LDPC码和HDPC码进行二级预编码.编码的第二步的修改使编码端更加有效地生成编码符号,而且新算法实现了由在21有限域GF(2)上的运算到28阶有限域GF(256)上的运算的改变.最后,利用ns-3环境实现的仿真结果进一步证明新算法提高了服务覆盖面,降低了收听延时,从而加强了移动多播传输的可靠性.