We consider uncoordinated random uplink non-orthogonal multiple access (NOMA) systems using a set of predetermined power levels. We propose to optimize the probabilities of selection of power levels in order to minimize performance metrics as block error probability (BLEP) or bit error probability (BEP). When the multiuser detection algorithm at the BS treats at most two colliding users' packets, our optimization problem is a quadratic programming problem. For more colliding users' packets, we solve the problem iteratively. Our solution is original because it applies to any multiuser detection algorithm and any set of power levels.

翻译：我们研究采用一组预定功率等级的非协调随机上行链路非正交多址接入（NOMA）系统。为最小化块错误概率（BLEP）或比特错误概率（BEP）等性能指标，我们提出优化功率等级的选择概率。当基站处的多用户检测算法最多处理两个碰撞用户数据包时，该优化问题可建模为二次规划问题。对于更多碰撞用户数据包的情况，我们通过迭代方法求解该问题。本方案的创新性在于其适用于任意多用户检测算法及任意功率等级集合。