human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "power allocation in two hop amplify and forward mimo relay systems with qos requirements"
  Abstract: The problem of minimizing the total power consumption while satisfying different quality-of-service (QoS) requirements in a two-hop multiple-input multiple-output (MIMO) network with a single nonregenerative relay is considered. As shown by Y. Rong [“Multihop nonregenerative MIMO relays: QoS considerations,” IEEE Trans. Signal Process., vol. 59, no. 1, pp. 209-303, 2011] in [1], the optimal processing matrices for both linear and nonlinear transceiver architectures lead to the diagonalization of the source-relay-destination channel so that the power minimization problem reduces to properly allocating the available power over the established links. Unfortunately, finding the solution of this problem is numerically difficult as it is not in a convex form. To overcome this difficulty, existing solutions rely on the computation of upper- and lower-bounds that are hard to obtain or require the relaxation of the QoS constraints. In this work, a novel approach is devised for both linear and nonlinear transceiver architectures, which allows to closely approximate the solutions of the nonconvex power allocation problems with those of convex ones easy to compute in closed-form by means of multistep procedures of reduced complexity. Computer simulations are used to assess the performance of the proposed approach and to make comparisons with alternatives.

Connected through hyperedge HE-1 (induced by source paper "energy efficiency optimization in relay assisted mimo systems with perfect and statistical csi"):
  with members:
    - "cooperative algorithms for mimo amplify and forward relay networks"
    - "energy efficiency optimization for mimo broadcast channels"
    - "joint source and relay precoding designs for mimo two way relaying based on mse criterion"
    - "framework for link level energy efficiency optimization with informed transmitter"
    - "energy efficient precoding for multiple antenna terminals"
    - "energy efficient resource allocation in multiuser mimo systems a game theoretic framework"
    - "on the capacity and diversity multiplexing tradeoff of the two way relay channel"
    - "energy efficient communications in cdma networks a game theoretic analysis considering operating costs"

Connected through hyperedge HE-2 (induced by source paper "convex separable problems with linear constraints in signal processing and communications"):
  with members:
    - "on the precoder design of a wireless energy harvesting node in linear vector gaussian channels with arbitrary input distribution"
    - "duality and optimization for generalized multi hop mimo amplify and forward relay networks with linear constraints"
    - "a tutorial on the optimization of amplify and forward mimo relay systems"
    - "transmission with energy harvesting nodes in fading wireless channels optimal policies"
    - "separable convex optimization problems with linear ascending constraints"

Connected through hyperedge HE-3 (induced by source paper "convex separable problems with linear and box constraints"):
  with members:
    - "convex separable problems with linear constraints in signal processing and communications"
    - "separable convex optimization problems with linear ascending constraints"

Connected through hyperedge HE-4 (induced by source paper "duality and optimization for generalized multi hop mimo amplify and forward relay networks with linear constraints"):
  with members:
    - "a tutorial on the optimization of amplify and forward mimo relay systems"
    - "mimo b mac interference network optimization under rate constraints by polite water filling and duality"
    - "duality polite water filling and optimization for mimo b mac interference networks and itree networks"

Connected through hyperedge HE-5 (induced by source paper "a tutorial on the optimization of amplify and forward mimo relay systems"):
  with members:
    - "asymptotic capacity and optimal precoding in mimo multi hop relay networks"
    - "transceiver design for dual hop nonregenerative mimo ofdm relay systems under channel uncertainties"
    - "achievable rate regions for bi directional relaying"
    - "diversity of mimo multihop relay channels"
    - "optimal space time codes for the mimo amplify and forward cooperative channel"

Question: Please tell me which class the center node 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)