Research On Feedback Enhancement Algorithm For MBMS Service

To meet the growing data demand of users,Multimedia Broadcast Multicast Service(MBMS)service was first introduced by 3GPP in 2005,and since then,3 GPP has carried out a lot of work to gradually improve the MBMS standard,which is a point-to-multipoint multimedia data transmission service from a single source entity to all users in the service area.MBMS service can serve a large number of users with the same demand with fewer resources than unicast service,which greatly relieves the increasingly tight airspace resources.However,at the same time,MBMS service does not guarantee the correct reception of data at the receiving end,and the issue of how to balance the transmission rate and reliability of MBMS service has received widespread attention in the industry.In this paper,three feedback enhancement algorithms are designed from the perspective of uplink feedback,and then the impact of feedback enhancement algorithms on the reliability and system capacity of MBMS services is explored.This thesis mainly includes the following three innovations:first is the design and implementation of feedback enhancement algorithm for MBMS service;second is the improvement of MBMS service based on 256QAM high-order modulation;thrid is the design and implementation of hybrid algorithm for multicast multicast and unicast.Firstly,this thesis introduces the process of building a 5G systemlevel simulation platform for simulating user access,which provides platform support for the design and performance analysis of feedback enhancement algorithms.Then three feedback enhancement algorithms for MBMS services are designed based on CQI feedback and ACK/NACK feedback.The specific role of these three feedback enhancement algorithms is to increase the MCS level of the group users as much as possible on the basis of ensuring the system reliability,thus improving the throughput of the whole system.Next is the incorporation of 256QAM high-order modulation on the MBMS system to explore the effect of highorder modulation on the performance of the MBMS system.Finally,a hybrid algorithm for multicast multicast and unicast is designed based on the RSRP threshold method,and different RSRP thresholds are selected to investigate the impact of the thresholds on the performance of the hybrid system.From the simulation results,the CQI and ACK/NACK joint feedback enhancement algorithm used in this thesis performs better in reliability and system performance than the other two algorithms.In exploring the impact of 256QAM high-order modulation on the performance of MBMS system,through the comparison and analysis of multiple groups of cases,it is concluded that 256QAM can improve MBMS performance when the number of users is small,and when the number of users is large,it can improve the performance of MBMS.The conclusion that there is little improvement in MBMS performance.Finally,through the comparison and analysis of the MBMS and unicast hybrid transmission system and the MBMS system,it is found that the hybrid transmission system has a great improvement in the average user throughput and user edge throughput compared with the MBMS system.Based on the above advantages,the feedback enhancement algorithm researched in this thesis provides a certain reference for future MBMS-related research work,and has the ability to be implemented in the existing network to a certain extent.