非正交多址下行链路的资源分配与仿真

Non-orthogonal multiple access(downlink): Resource allocation and simulation

非正交多址(NOMA)技术是一种多载波技术,是第五代移动通信中的一项重要技术。提出一种基于稀疏码映射的非正交多址下行链路模型,用来增加用户的复用增益,并且提高基站分配功率较弱用户的安全性。在该模型下采用不同的功率域用户分配方案,包括随机用户分配方案、基于大尺度衰落的用户分配方案和基于贪婪算法的用户分配方案,并比较这几种分配方案的频谱效率,此外,探究了同一种用户分配方案下路径损耗指数对频谱效率的影响。仿真结果表明:在基于稀疏码映射的非正交多址下行链路模型中,与随机用户分配方案相比,基于大尺度衰落的用户分配方案具有频谱效率高、操作简单、便于实现的优点;基于贪婪算法的用户分配方案则具有更高的频谱效率,但计算的复杂程度较高,现阶段不便于实现;路径损耗指数的增加对系统频谱效率有消极影响。

Non-orthogonal multiple access(NOMA) is a kind of multi-carrier technology, which is one of the most important parts in 5th generation communications. A NOMA downlink scheme based on Sparse-Code-Mapping will be raised in this paper in order to increase the multi-user power gain of the system and increase the security of weaker users. The scheme uses different allocation plans, including Random Sub-carrier Allocation, Large Scale Fading Sub-carrier Allocation and Fair Greedy Sub-carrier Allocation. Their system performances will be simulated and compared in this essay by testing their spectral-efficiency. Additionally, this paper will simulate the effect of large-scale-fading on the NOMA downlink system. The simulation result shows that,among those sub-carrier allocation schemes, Large Scale Fading allocation has better spectral-efficiency performance compared with Random allocation and Large Scale Fading allocation is easy to operate and put into practice. However, Fair Greedy Allocation could acquire highest spectral- efficiency but the calculation of Fair Greedy Allocation could be more complicated, hence it is hard to be applied into actual communication systems so far. Moreover, while pass-loss exponent gets higher, spectral of the whole NOMA downlink system will have negative effect.