Research On The Multiple Access Technology Of The Satellite Network

With the constant development of satellite communication technology,satellite communication has expanded to various aspects covering voice,broadband multimedia and data business.The convergence of various businesses also raises higher demand for the utilization rate and guarantee for time delay.This thesis will focus on the satellite multiple access protocols,and improve the deficiencies of existing protocols to ensure the utilization of links and reduce end-to-end latency for services.The specific contents and innovation points of this research are as follow:1.Aimed at ON/OFF business that suddenly bursting out,this thesis deeply studied the BTDAMA.There is a problem in this plan,that the control center dispense equal resource to user of ON status and when the traffic of users are different,the high traffic user is dispensed with less resource and low traffic user is dispensed with more resource.Based on this,the BTDAMA-DA plan is proposed which dispenses resources dynamically to users according to business distribution of users,meanwhile eliminating estimated errors in combination of distribution according to needs so that the resources the dispensed to users change dynamically according to the arriving traffic of users to reduce the end-to-end time delay for users of high traffic.2.This thesis deeply studied the CFDAMA and its application scenarios.The problem of this scheme is that the utilization rate of free time slots is lower when there are more users and it takes longer resource appointment time delay for each business transmission and the transmission resources ratio occupied by the appointment stage is higher.Based on this,the CRDAMA plan is picked up,according to which the users send competitively in free time slots in optimal entry probability to avoid the control center from dispensing resources to users without business transmission demand which are wasting the resource and the free slot resource utilization rate is improved.This thesis gave out the calculation plan of user optimal entry probability according to mathematical analysis and analyze the performance of this plan according to mathematical model.3.This thesis enhanced the CRDAMA protocol based on the current SCMA technology.In random transmission,by using the overload characteristic of SCMA,the users occupy resources in nonorthogonal manner and the available resources are expanded further for the limited physical resources to reduce the collision probability in the course of random transmission.Therefore the performance of CRDAMA protocol is further improved.Since there is Doppler frequency shift in satellite link,this thesis analyzed the error code situation of enhanced CRDAMA protocol under the Doppler frequency shift of satellite link and designed the optimal frame size of enhanced CRDAMA in combination of different link retransmission mechanisms to maximize the link efficiency.