| With the rapid development of wireless communication,channel coding technology,as one of the most important technologies to ensure transmission reliability and efficiency,is facing more and more challenges with the complex wireless communication.In many cases,it is difficult for the transmitter to obtain accurate channel state information in advance so that the fixed-rate codes cannot guarantee the reliability of communication transmission effectively.Hence,rateless codes that can adapt to variable channel conditions have emerged.As a new type of rateless codes proposed in 2012,Spinal codes can be capacity-achieving over both additive white Gaussian noise channel and binary symmetric channel.In addition,the simple encoding structure of Spinal codes provides good resilience to analog noise(when used over AWGN)or bit errors(when used over BSC),proving that Spinal codes have great research potential and development value for time-varying channels,such as the deep space communication.Firstly,this dissertation introduces the research development of channel coding technology,and the performance advantages of rateless codes over time-varying channel.Then we introduce the structure and basic principles of Spinal codes,and analyze the performance advantages of Spinal codes by comparing with other excellent codes.By optimizing the transmission scheme of Spinal codes,we propose high performance puncturing pattern to achieve higher transmission rate and lower BER.The following shows specific research contents.(1)Research on the error probability of Spinal codes.The analysis on the error probability of Spinal codes still leaves rooms for improvement.Hence,based on the property of Spinal codes,we derive the upper bound of average error probability of Spinal codes over both BSC and AWGN channel from Random-Coding Union bound.Simulation results show that the proposed bounds are tight bounds that can serve as the theoretical basis of high efficiency puncturing techniques.(2)Research on the puncturing pattern for Spinal codes.In order to improve the transmission rate,we propose a puncturing pattern named inverted triangle-shaped puncturing based on the characteristics of Spinal codes.By taking the error probability analysis results as the constraint condition,we formulate the design of optimization model aimming to improve the transmission rates,and then obtain the inverted triangle-shaped puncturing pattern.The key idea is to reduce excessive transmission of symbols corresponding to the former parts of pass,and protect the tail symbols effectively,providing higher transmission rate and lower BER.Simulation results show that the proposed puncturing,compared with the uniform puncturing pattern,has obvious advantage.(3)Research on the further improvements of puncturing pattern.We combine the inverted triangle-shaped puncturing pattern with the uniform puncturing pattern to propose the joint puncutirng,which can provide a finer-grained rate.Furthermore,we proposed an associated effective puncturing order.Simulation results show that the joint puncturing after optimization on the puncturing order can take full advantage of forward increasing redundancy,providing a better transmission rate by reducing the redundancy. |
