human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "signal processing for mimo noma present and future challenges"):
  Abstract: Non-orthogonal multiple access (NOMA), as the newest member of the multiple access family, is envisioned to be an essential component of 5G mobile networks. The combination of NOMA and multi-antenna multi-input multi-output (MIMO) technologies exhibits a significant potential in improving spectral efficiency and providing better wireless services to more users. In this article, we introduce the basic concepts of MIMO-NOMA and summarize the key technical problems in MIMO-NOMA systems. Then, we explore the problem formulation, beamforming, user clustering, and power allocation of single/multi-cluster MIMO-NOMA in the literature along with their limitations. Furthermore, we point out an important issue of the stability of successive interference cancellation (SIC) that arises using achievable rates as performance metrics in practical NOMA/MIMO-NOMA systems. Finally, we discuss incorporating NOMA with massive/millimeter wave MIMO, and identify the main challenges and possible future research directions in this area.

Includes members:
  Member "spectrum and energy efficient beamspace mimo noma for millimeter wave communications using lens antenna array":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "intelligent reflecting and transmitting surface aided millimeter wave massive mimo")
  Member "on optimal power allocation for downlink non orthogonal multiple access systems":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "downlink analysis of noma enabled cellular networks with 3gpp inspired user ranking")
  Member "design of massive mimo noma with limited feedback":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "interplay between noma and other emerging technologies a survey")
  Member "a minorization maximization method for optimizing sum rate in the downlink of non orthogonal multiple access systems":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "resource allocation technique for hybrid tdma noma system with opportunistic time assignment")
  Member "non orthogonal multiple access noma for downlink multiuser mimo systems user clustering beamforming and power allocation":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "optical rate splitting multiple access for visible light communications")

Question: Please tell me which class the source paper belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.IT(Information Theory)