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 "a tutorial on the optimization of amplify and forward mimo relay systems"):
  Abstract: The remarkable promise of multiple-input multiple-output (MIMO) wireless channels has motivated an intense research activity to characterize the theoretical and practical issues associated with the design of transmit (source) and receive (destination) processing matrices under different operating conditions. This activity was primarily focused on point-to-point (single-hop) communications but more recently there has been an extensive work on two-hop or multi-hop settings in which single or multiple relays are used to deliver the information from the source to the destination. The aim of this tutorial is to provide an up-to-date overview of the fundamental results and practical implementation issues in designing amplify-and-forward MIMO relay systems.

Includes members:
  Member "power allocation in two hop amplify and forward mimo relay systems with qos requirements":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "energy efficiency optimization in relay assisted mimo systems with perfect and statistical csi")
  Member "asymptotic capacity and optimal precoding in mimo multi hop relay networks":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "average sep optimal precoding for correlated massive mimo with zf detection an asymptotic analysis")
  Member "transceiver design for dual hop nonregenerative mimo ofdm relay systems under channel uncertainties":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "mmwave amplify and forward mimo relay networks with hybrid precoding combining design")
  Member "achievable rate regions for bi directional relaying":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "resource allocation and outage analysis for an adaptive cognitive two way relay network")
  Member "diversity of mimo multihop relay channels":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "cooperation and underlay mode selection in cognitive radio network")
  Member "optimal space time codes for the mimo amplify and forward cooperative channel":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "unmanned aerial vehicle assisted cellular communication")

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)