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 beamforming design for multi user wireless information and power transfer"
  Abstract: In this paper, we propose a joint beamforming algorithm for a multiuser wireless information and power transfer (MU-WIPT) system that is compatible with the conventional multiuser multiple input multiple output (MU-MIMO) system. The proposed joint beamforming vectors are initialized using the well established MU-MIMO zero-forcing beamforming (ZFBF) and are further updated to maximize the total harvested energy of energy harvesting (EH) users and guarantee the signal to interference plus noise ratio (SINR) constraints of the co-scheduled information decoding (ID) users. When ID and EH users are simultaneously served by joint beamforming vectors, the harvested energy can be increased at the cost of an SINR loss for ID users. To characterize the SINR loss, the target SINR ratio,u, is introduced as the target SINR (i.e., SINR constraint) normalized by the received SINR achievable with ZFBF. Based on that ratio, the sum rate and harvested energy obtained from the proposed algorithm are analyzed under perfect/imperfect channel state information at the transmitter (CSIT). Through simulations and numerical results, we validate the derived analyses and demonstrate the EH and ID performance compared to both state of the art and conventional schemes.

Connected through hyperedge HE-1 (induced by source paper "a retrodirective wireless power transfer scheme for ambient backscatter systems"):
  with members:
    - "design of ambient backscatter training for retrodirective wireless power transfer"
    - "retrodirective large antenna energy beamforming in backscatter multi user networks"
    - "retrodirective multi user wireless power transfer with massive mimo"
    - "modulation in the air backscatter communication over ambient ofdm carrier"
    - "performance analysis of massive mimo for cell boundary users"
    - "joint wireless information and energy transfer with reduced feedback in mimo interference channels"
    - "energy beamforming with one bit feedback"
    - "optimized training design for wireless energy transfer"

Connected through hyperedge HE-2 (induced by source paper "design of ambient backscatter training for retrodirective wireless power transfer"):
  with members:
    - "retrodirective large antenna energy beamforming in backscatter multi user networks"
    - "retrodirective multi user wireless power transfer with massive mimo"
    - "next generation backscatter communication systems techniques and applications"
    - "ambient backscatter communications a contemporary survey"
    - "modulation in the air backscatter communication over ambient ofdm carrier"
    - "inter technology backscatter towards internet connectivity for implanted devices"
    - "communications and signals design for wireless power transmission"
    - "wireless powered communication opportunities and challenges"

Connected through hyperedge HE-3 (induced by source paper "robust energy efficient beamforming in misome swipt systems with proportional secrecy rate"):
  with members:
    - "robust secrecy energy efficient beamforming in misome swipt systems with proportional fairness"
    - "rf based energy harvesting in decode and forward relaying systems ergodic and outage capacities"
    - "secure beamforming in full duplex swipt systems with loopback self interference cancellation"
    - "large scale multiantenna multisine wireless power transfer"
    - "dynamic cross layer beamforming in hybrid powered communication systems with harvest use trade strategy"
    - "joint optimization of power and data transfer in multiuser mimo systems"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "network densification in 5g from the short range communications perspective"

Connected through hyperedge HE-4 (induced by source paper "robust secrecy energy efficient beamforming in misome swipt systems with proportional fairness"):
  with members:
    - "secure beamforming in full duplex swipt systems with loopback self interference cancellation"
    - "robust energy efficient beamforming in misome swipt systems with proportional secrecy rate"
    - "large scale multiantenna multisine wireless power transfer"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "network densification in 5g from the short range communications perspective"
    - "wireless information and power transfer nonlinearity waveform design and rate energy tradeoff"
    - "an overview of sustainable green 5g networks"
    - "communications and signals design for wireless power transmission"

Connected through hyperedge HE-5 (induced by source paper "secure swipt for directional modulation aided af relaying networks"):
  with members:
    - "spectral and energy efficient wireless powered iot networks noma or tdma"
    - "an overview of sustainable green 5g networks"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "secrecy wireless information and power transfer challenges and opportunities"
    - "relaying strategies for wireless powered mimo relay networks"
    - "to harvest and jam a paradigm of self sustaining friendly jammers for secure af relaying"
    - "relay selection improves the security reliability trade off in cognitive radio systems"
    - "noncoherent relaying in energy harvesting communication systems"

Connected through hyperedge HE-6 (induced by source paper "energy sustainable iot with individual qos constraints through miso swipt multicasting"):
  with members:
    - "jointly optimal spatial channel assignment and power allocation for mimo swipt systems"
    - "random access analysis for massive iot networks under a new spatio temporal model a stochastic geometry approach"
    - "robust an aided beamforming and power splitting design for secure miso cognitive radio with swipt"
    - "power allocation and scheduling for swipt systems with non linear energy harvesting model"
    - "multiuser miso beamforming for simultaneous wireless information and power transfer"
    - "joint transmit beamforming and receive power splitting for miso swipt systems"
    - "beamforming for miso interference channels with qos and rf energy transfer"
    - "robust beamforming for wireless information and power transmission"

Connected through hyperedge HE-7 (induced by source paper "theory and experiment for wireless powered sensor networks how to keep sensors alive"):
  with members:
    - "experiment modeling and analysis of wireless powered sensor network for energy neutral power management"
    - "distributed charging control in broadband wireless power transfer networks"
    - "adaptively directional wireless power transfer for large scale sensor networks"
    - "communications and signals design for wireless power transmission"
    - "multiuser mimo wireless energy transfer with coexisting opportunistic communication"
    - "joint transmit beamforming and receive power splitting for miso swipt systems"
    - "application of smart antenna technologies in simultaneous wireless information and power transfer"
    - "multi antenna wireless powered communication with energy beamforming"

Connected through hyperedge HE-8 (induced by source paper "theory and experiment for wireless powered sensor networks how to keep multiple sensor nodes alive"):
  with members:
    - "experiment modeling and analysis of wireless powered sensor network for energy neutral power management"
    - "distributed charging control in broadband wireless power transfer networks"
    - "adaptively directional wireless power transfer for large scale sensor networks"
    - "joint transmit beamforming and receive power splitting for miso swipt systems"
    - "multi antenna wireless powered communication with energy beamforming"

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)