Resource Allocation For Energy Efficiency Maximization Of Layered Multicast Based On Feedback In SCMA Systems

With the explosive growth of mobile communication services,the ensuing energy consumption is increasing at an alarming rate,so the future 5G cellular network will support 1000 times of data growth and 100 times energy efficiency(Energy Efficiency,EE).)Ascension,this poses new challenges for future multiple access technologies.However,the current multiple access technology is limited by orthogonal resources and cannot meet the requirements of 5G mass connection and energy efficiency.Therefore,research on multiple access technology has also gradually transitioned fr-om Orthogonal Frequency Division Multiple Access(OFDMA)to Non-Orthogonal Multiple Access(NOMA).On the other hand,wireless multicast transmission technology can save a lot of network resources,thereby improving resource utilization.The multimedia market demand brought about by the rapid development of the Internet has quickly become a resear-ch hotspot.However,in a conventional multicast system,the multicast rate is limited by the users with the worst channel conditions in the system,resulting in limited thr-oughput of the entire system.In view of the above background,in order to improve the energy efficiency of the network,this thesis studies the hierarchical multicast resource allocation strategy in the Sparse Code Multiple Access(SCMA)system,and introduces a reasonable limited feedback strategy.Reduced the amount of feedback from the system.The specific research contents of the thesis are as follows:Firstly,this thesis investigates the resear-ch background and research status of the layered multicast scheme in SCMA,expounds the I importance of improving energy efficiency,and summarizes the key technologies related to SCMA and layered multicast systems.Secondly,this thesis studies the hierarchical multicast scheme under the condition of full feedback in SCMA system for the problem of low multicast scheme EE in traditional OFDMA system.The network energy efficiency(EE)expression in this scenario is derived by formula.In order to further optimize the network EE,a two-stage fast suboptimal algorithm for codebook allocation and power allocation decoupling is proposed.The simulation results show that the proposed algorithm can effectively improve the network EE in the SCMA hierarchical multicast scenario,and a feasible suboptimal solution is obtained.Finally,in view of the problem of large feedback load of multicast system in practical applications,this thesis studies the hierarchical multicast scheme under limited feedback conditions in SCMA system.Firstly,a reasonable hierarchical multicast multi-feedback feedback strategy is introduced,and then the corresponding two-stage codebook allocation and resource allocation are carried out under the condition of limited feedback.The simulation results show that the scheme can effectively reduce the feedback load of the uplink under the premise of ensuring the overall performance of the system,making the scheme closer to practical applications.