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: "enhancing wireless information and power transfer by exploiting multi antenna techniques"
  Abstract: This article reviews an emerging wireless information and power transfer (WIPT) technique with an emphasis on its performance enhancement employing multi-antenna techniques. Compared to traditional wireless information transmission, WIPT faces numerous challenges. First, it is more susceptible to channel fading and path loss, resulting in a much shorter power transfer distance. Second, it gives rise to the issue of how to balance spectral efficiency for information transmission and energy efficiency for power transfer in order to obtain an optimal tradeoff. Third, there exists a security issue for information transmission in order to improve power transfer efficiency. In this context, multi-antenna techniques, e.g. energy beamforming, are introduced to solve these problems by exploiting spatial degree of freedom. This article provides a tutorial on various aspects of multi-antenna based WIPT techniques, with a focus on tackling the challenges by parameter optimization and protocol design. In particular, we investigate the WIPT tradeoffs based on two typical multi-antenna techniques: the limited feedback multi-antenna technique for short-distance transfer; and the large-scale multiple-input multiple-output (LS-MIMO, also known as massive MIMO) technique for long-distance transfer. Finally, simulation results validate the effectiveness of the proposed schemes.

Connected through hyperedge HE-1 (induced by source paper "wireless energy beamforming using received signal strength indicator feedback"):
  with members:
    - "a general design framework for mimo wireless energy transfer with limited feedback"
    - "wireless powered communication opportunities and challenges"
    - "throughput optimization for massive mimo systems powered by wireless energy transfer"
    - "multiuser mimo wireless energy transfer with coexisting opportunistic communication"
    - "optimized training for net energy maximization in multi antenna wireless energy transfer over frequency selective channel"
    - "energy beamforming with one bit feedback"
    - "optimized training design for wireless energy transfer"
    - "dynamic resource allocation for multiple antenna wireless power transfer"

Connected through hyperedge HE-2 (induced by source paper "wireless energy transfer to a pair of energy receivers using signal strength feedback"):
  with members:
    - "wireless energy beamforming using received signal strength indicator feedback"
    - "multiuser mimo wireless energy transfer with coexisting opportunistic communication"
    - "optimized training for net energy maximization in multi antenna wireless energy transfer over frequency selective channel"
    - "energy beamforming with one bit feedback"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "energy efficient optimization for wireless information and power transfer in large scale mimo systems employing energy beamforming"
    - "mimo broadcasting for simultaneous wireless information and power transfer"

Connected through hyperedge HE-3 (induced by source paper "power efficient and secure wpcns with hardware impairments and non linear eh circuit"):
  with members:
    - "spectral efficiency of multipair massive mimo two way relaying with hardware impairments"
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "max min fair beamforming for swipt systems with non linear eh model"
    - "power allocation for secure swipt systems with wireless powered cooperative jamming"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "on the spectral efficiency of massive mimo systems with low resolution adcs"
    - "wireless powered communication networks an overview"

Connected through hyperedge HE-4 (induced by source paper "physical layer service integration in 5g potentials and challenges"):
  with members:
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "an overview of sustainable green 5g networks"
    - "gsvd based precoding in mimo systems with integrated services"
    - "robust artificial noise aided transmit design for multi user miso systems with integrated services"
    - "wireless powered communication opportunities and challenges"
    - "multi antenna relay aided wireless physical layer security"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "wireless networks with rf energy harvesting a contemporary survey"

Connected through hyperedge HE-5 (induced by source paper "joint resource allocation in swipt based multi antenna decode and forward relay networks"):
  with members:
    - "power allocation for secure swipt systems with wireless powered cooperative jamming"
    - "relaying strategies for wireless powered mimo relay networks"
    - "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"
    - "information and energy cooperation in ofdm relaying protocols and optimization"
    - "joint power splitting and antenna selection in energy harvesting relay channels"
    - "energy harvesting for physical layer security in ofdma networks"
    - "wireless information and energy transfer for two hop non regenerative mimo ofdm relay networks"

Connected through hyperedge HE-6 (induced by source paper "simultaneous wireless information and power transfer in cooperative relay networks with rateless codes"):
  with members:
    - "optimum transmission policies for energy harvesting sensor networks powered by a mobile control center"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "wireless information and energy transfer for two hop non regenerative mimo ofdm relay networks"
    - "outage analysis and optimization for time switching based two way relaying with energy harvesting relay node"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"
    - "wireless information and power transfer with full duplex relaying"

Connected through hyperedge HE-7 (induced by source paper "secure swipt networks based on a non linear energy harvesting model"):
  with members:
    - "robust layered transmission in secure miso multiuser unicast cognitive radio systems"
    - "secrecy wireless information and power transfer challenges and opportunities"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "multi objective optimization for robust power efficient and secure full duplex wireless communication systems"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "simultaneous wireless information and power transfer in modern communication systems"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"

Connected through hyperedge HE-8 (induced by source paper "max min fair beamforming for swipt systems with non linear eh model"):
  with members:
    - "secure swipt networks based on a non linear energy harvesting model"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "secure and green swipt in distributed antenna networks with limited backhaul capacity"
    - "max min fair wireless energy transfer for secure multiuser communication systems"
    - "secrecy wireless information and power transfer with miso beamforming"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"

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)