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: "joint source and relay precoding designs for mimo two way relaying based on mse criterion"
  Abstract: Properly designed precoders can significantly improve the spectral efficiency of multiple-input multiple-output (MIMO) relay systems. In this paper, we investigate joint source and relay precoding design based on the mean-square-error (MSE) criterion in MIMO two-way relay systems, where two multiantenna source nodes exchange information via a multiantenna amplify-and-forward relay node. This problem is non-convex and its optimal solution remains unsolved. Aiming to find an efficient way to solve the problem, we first decouple the primal problem into three tractable subproblems, and then propose an iterative precoding design algorithm based on alternating optimization. The solution to each subproblem is optimal and unique, thus the convergence of the iterative algorithm is guaranteed. Second, we propose a structured precoding design to lower the computational complexity. The proposed precoding structure is able to parallelize the channels in the multiple access (MAC) phase and broadcast (BC) phase. It thus reduces the precoding design to a simple power allocation problem. Last, for the special case where only a single data stream is transmitted from each source node, we present a source-antenna-selection (SAS)-based precoding design algorithm. This algorithm selects only one antenna for transmission from each source and thus requires lower signalling overhead. Comprehensive simulation is conducted to evaluate the effectiveness of all the proposed precoding designs.

Connected through hyperedge HE-1 (induced by source paper "utility energy efficiency oriented user association with power control in heterogeneous networks"):
  with members:
    - "joint power allocation and user association optimization for massive mimo systems"
    - "distributed pricing based user association for downlink heterogeneous cellular networks"
    - "user association for load balancing in heterogeneous cellular networks"

Connected through hyperedge HE-2 (induced by source paper "a survey on mimo transmission with discrete input signals technical challenges advances and future trends"):
  with members:
    - "asymptotic performance analysis of a k hop amplify and forward relay mimo channel"
    - "iterative distributed minimum total mse approach for secure communications in mimo interference channels"
    - "asymptotic analysis of su mimo channels with transmitter noise and mismatched joint decoding"
    - "secure massive mimo transmission with an active eavesdropper"
    - "interference aligned space time transmission with diversity for the 2 times 2 x network"
    - "space time encoded miso broadcast channel with outdated csit an error rate and diversity performance analysis"
    - "high snr asymptotics of mutual information for discrete constellations with applications to bicm"
    - "differential distributed space time coding with imperfect synchronization in frequency selective channels"

Connected through hyperedge HE-3 (induced by source paper "optimal dof region for the asymmetric two pair mimo two way relay channel"):
  with members:
    - "optimal degrees of freedom region for the asymmetric mimo y channel"
    - "generalized signal alignment on the achievable dof for multi user mimo two way relay channels"
    - "cyclic communication and the inseparability of mimo multi way relay channels"
    - "mimo multiway relaying with clustered full data exchange signal space alignment and degrees of freedom"
    - "mimo multiway relaying with pairwise data exchange a degrees of freedom perspective"
    - "generalized signal alignment for arbitrary mimo two way relay channels"
    - "approximate sum capacity of the y channel"
    - "degrees of freedom for the mimo multi way relay channel"

Connected through hyperedge HE-4 (induced by source paper "wireless powered cooperative communications power splitting relaying with energy accumulation"):
  with members:
    - "fronthaul constrained cloud radio access networks insights and challenges"
    - "joint power splitting and antenna selection in energy harvesting relay channels"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "evolution toward 5g multi tier cellular wireless networks an interference management perspective"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"
    - "simultaneous information and power transfer for broadband wireless systems"
    - "relaying protocols for wireless energy harvesting and information processing"

Connected through hyperedge HE-5 (induced by source paper "relaying strategies for wireless powered mimo relay networks"):
  with members:
    - "distributed power splitting for swipt in relay interference channels using game theory"
    - "joint wireless information and power transfer for an autonomous multiple antenna relay system"
    - "joint power splitting and antenna selection in energy harvesting relay channels"
    - "joint wireless information and power transfer in a three node autonomous mimo relay network"
    - "joint resource optimization for multicell networks with wireless energy harvesting relays"
    - "user cooperation in wireless powered communication networks"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "relaying protocols for wireless energy harvesting and information processing"

Connected through hyperedge HE-6 (induced by source paper "mse based precoding for mimo downlinks in heterogeneous networks"):
  with members:
    - "what will 5g be"
    - "linear precoding designs for amplify and forward multiuser two way relay systems"
    - "decomposition by successive convex approximation a unifying approach for linear transceiver design in heterogeneous networks"
    - "cooperative multi cell block diagonalization with per base station power constraints"
    - "pilot contamination and precoding in multi cell tdd systems"

Connected through hyperedge HE-7 (induced by source paper "beamforming design for full duplex two way amplify and forward mimo relay"):
  with members:
    - "joint beamforming optimization and power control for full duplex mimo two way relay channel"
    - "practical full duplex physical layer network coding"

Connected through hyperedge HE-8 (induced by source paper "generalized signal alignment on the achievable dof for multi user mimo two way relay channels"):
  with members:
    - "a new dof upper bound and its achievability for k user mimo y channels"
    - "generalized signal alignment for mimo two way x relay channels"
    - "mimo multiway relaying with clustered full data exchange signal space alignment and degrees of freedom"
    - "beyond one way communication degrees of freedom of multi way relay mimo interference networks"
    - "mimo multiway relaying with pairwise data exchange a degrees of freedom perspective"
    - "generalized signal alignment for arbitrary mimo two way relay channels"
    - "degrees of freedom for the mimo multi way relay channel"
    - "the degrees of freedom of the mimo y 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)