Research On Digital Fountain Codes And It’s Applications In Green Communications

With the increasingly rich network information and the diverse service delivery,there exists massive data transmission in most cases. Therefore, a new challenge hasbeen put forward to information transmission, among which the channel coding is a keyfactor. A new coding scheme of strong scalability and compatibility is needed, takingdifferent needs of different users into account. Fortunately, the digital fountain codeemerges as the times require. Meanwhile, the increase of energy consumption and theaccompanying serious environmental problems put forward new requirements for thewhole communication industry. To solve these problems, we need to build an efficientand environment-welled communication system and extensive-to the wholecommunication industry, which brings an opportunity to the rise of greencommunication.In this paper, we first explore the performance of LT code in digital fountain codes.The LT code was applied to AWGN channel, at the same time a new decodingalgorithm was discovered which is similar to the BP algorithm of LDPC. To solve theproblem of the original data full-coverage for the LT code distribution, we propose anew encoding scheme of global optimization choice for the original data, and makeimprovement to the coding package of degree-2in the generated matrix. At the sametime, the mechanism of getting rid of four rings is added to improve the successfuldecoding rate under lower overhead in LT decoding. For the Raptor code, we invest thespecific progress of encoding and decoding of Raptor code in the standard of3GPPMBMS. The simulation results are given to make comparison between Raptor code andLT code, which shows that the performance of Raptor code is better but with higherencoding complexity.Secondly, under the MFSK modulation system model in WSNs, we present thefirst in-deep analysis on the energy efficiency of LT coded modulation and make acomparison of energy consumption with MFSK modulation in different coding system,which are LT code scheme, other codes schemes (like BCH codes and convolutioncodes) and non-coding scheme. The numerical results show that there is a critical distanced between the LT code system and other schemes. Whend d, the systemadopts non-code scheme has certain advantage, but the energy saving is not muchobvious compared with LT code scheme. On the contrary, whend d, the MFSKmodulation system with the adoption of LT code has significant energy savingscompared with other schemes.