Research On Turbo Code And OvCDM

During the development of channel encoding,The code Researchers are always finding a kind of code which has near-optimum performance,low bit error rate and low decoding complexity.Berrou advanced Turbo codes in 1993.The Turbo codes have the near-optimum performance and low bit error rate,so it gets the wide care.In the development of the next generation mobile communication systems,it is well known that Turbo codes are the way of error correcting codes of high speed data channel.It has been adopted as the channel coding scheme by many international standards such as 802.16,LTE,WCDMA and CDMA2000.Bandwidth efficiency is one of the most important objectives in the design of mobile communication systems in the future.The other key objective is the distance between the BER(bit error ratio) curve and the Shannon limit when the bandwidth efficiency is fixed.Traditionally they are accomplished by combining advanced modulation and error-correcting codes.Overlapping Code Division Multiplexing(OvCDM) is a new technology that can increase the bandwidth efficiency and improve the BER performance together.There are bandwidth efficiency gain and produced constraint relations by symbols' overlapping,this is the key point.First,The paper surrounds The theory of endoding and decoding of Turbo code, describes related basis knowledge.Scendly,describes the theory of channel coding and the construction of Turbo code.Discussed the interleaving ways of Turbo code.Thirdly, we got the performance results by simulation based on the Turbo code structure described in LTE.This paper also researched the theories of OvCDM and proposed two improved OvCDM decoding algorithms and got the performance results by simulation in this paper.