Research On CPM Communication System For Short-burst Scenarios

The short-burst communication scenario is widely used in military communication,satellite communication and deep space communication because of its short communication duration and bursty characteristics,which makes it have certain anti-interference and anti-capture capabilities.In the short-burst communication scenario,channel resources are extremely valuable.Once the signal is mistaken or lost during transmission,the traditional communication system based on the ARQ mechanism will greatly waste the channel resources.This paper proposes a communication system for short burst scenarios that combines digital fountain codes and continuous phase modulation.The CPM signal has constant envelope and high power utilization rate.It is suitable for long-distance communication scenarios such as satellite communications and deep space communications As a channel coding,the digital fountain code overcomes the problems in the ARQ mechanism because it has no code rate.First of all,this paper introduces the basic principles of continuous phase modulation technology,and analyzes the signal model,phase path and state transition,modulation method,maximum likelihood decoding algorithm,and low complexity demodulation algorithm of CPM modulation.Based on these,the power spectrum characteristics and bit error rate performance of the CPM signal under different modulation parameters are analyzed and simulated in detail.The impact of modulation order,modulation index,pulse shaping function and other parameters of the CPM signal on the CPM performance are obtained.It lays the data foundation for the subsequent parameter selection in different short burst scenarios.Secondly,this paper studies the concept of digital fountain code and introduces the common channel model of fountain code.It analyzes the encoding and decoding principle of a digital fountain code LT code.The mathematical model of the ideal solitary wave distribution,the robust solitary wave distribution,the fixed degree distribution and other degree distribution functions are analyzed in detail from the theoretical and simulation aspects.At the same time,Raptor code,which is more suitable for noise channels,is introduced.The advantages and disadvantages of Raptor code and LT code are analyzed.It lays the foundation for the selection of coding and decoding methods in different short-burst scenarios.Finally,combining the characteristics of continuous phase modulation and digital fountain code,this paper proposes a fountain code + continuous phase modulation cascade communication system scheme for short-burst scenarios,and details the scheme.It overcomes the problems of channel occupation and delay caused by feedback under the traditional ARQ mechanism,and improves the efficiency of information transmission in short-burst scenarios.In addition,according to the specific communication scenarios,this article further refines the short-burst communication into two scenarios: active short-burst communication and passive short-burst communication according to the working mode of the two ends of the communication.Based on the performance analysis of the CPM system and the performance of the digital fountain code,combined with the specific characteristics of the two short burst scenarios,the system parameters in different scenarios are given,and the system performance is simulated.Based on the performance analysis of the CPM system and the performance of the digital fountain code,combined with the specific characteristics of the two short burst scenarios,the system parameters in different scenarios are given,and the system performance is simulated.