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: "network beamforming using relays with perfect channel information"
  Abstract: This paper is on beamforming in wireless relay networks with perfect channel information at relays, the receiver, and the transmitter if there is a direct link between the transmitter and receiver. It is assumed that every node in the network has its own power constraint. A two-step amplify-and-forward protocol is used, in which the transmitter and relays not only use match filters to form a beam at the receiver but also adaptively adjust their transmit powers according to the channel strength information. For a network with any number of relays and no direct link, the optimal power control is solved analytically. The complexity of finding the exact solution is linear in the number of relays. Our results show that the transmitter should always use its maximal power and the optimal power used at a relay is not a binary function. It can take any value between zero and its maximum transmit power. Also, this value depends on the quality of all other channels in addition to the relay's own channels. Despite this coupling fact, distributive strategies are proposed in which, with the aid of a low-rate broadcast from the receiver, a relay needs only its own channel information to implement the optimal power control. Simulated performance shows that network beamforming achieves the maximal diversity and outperforms other existing schemes. Then, beamforming in networks with a direct link are considered. We show that when the direct link exists during the first step only, the optimal power control is the same as that of networks with no direct link. For networks with a direct link during the second step, recursive numerical algorithms are proposed to solve the power control problem. Simulation shows that by adjusting the transmitter and relays' powers adaptively, network performance is significantly improved.

Connected through hyperedge HE-1 (induced by source paper "capitalizing backscatter aided hybrid relay communications with wireless energy harvesting"):
  with members:
    - "cooperative ambient backscatter communications for green internet of things"
    - "optimal time scheduling for wireless powered backscatter communication networks"
    - "ambient backscatter communications a contemporary survey"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "relaying protocols for wireless energy harvesting and information processing"

Connected through hyperedge HE-2 (induced by source paper "cooperative asynchronous non orthogonal multiple access with power minimization under qos constraints"):
  with members:
    - "an analysis of two user uplink asynchronous non orthogonal multiple access systems"
    - "exploiting full half duplex user relaying in noma systems"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "outage performance for cooperative noma transmission with an af relay"
    - "wireless network level partial relay cooperation a stable throughput analysis"
    - "interference mitigation using asynchronous transmission and sampling diversity"
    - "cooperative non orthogonal multiple access with simultaneous wireless information and power transfer"
    - "asynchronous orthogonal differential decoding for multiple access channels"

Connected through hyperedge HE-3 (induced by source paper "mmwave amplify and forward mimo relay networks with hybrid precoding combining design"):
  with members:
    - "low rf complexity technologies to enable millimeter wave mimo with large antenna array for 5g wireless communications"
    - "hybrid block diagonalization for massive multiuser mimo systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "transceiver design for dual hop nonregenerative mimo ofdm relay systems under channel uncertainties"
    - "distributed beamforming in wireless multiuser relay interference networks with quantized feedback"

Connected through hyperedge HE-4 (induced by source paper "energy efficiency of opportunistic device to device relaying under lognormal shadowing"):
  with members:
    - "dore an experimental framework to enable outband d2d relay in cellular networks"
    - "a stochastic geometric analysis of device to device communications operating over generalized fading channels"
    - "device relaying in cellular d2d networks a fairness perspective"
    - "effects of relay selection strategies on the spectral efficiency of wireless systems with half and full duplex nodes"
    - "a survey on device to device communication in cellular networks"
    - "energy efficiency optimization in relay assisted mimo systems with perfect and statistical csi"
    - "what will 5g be"
    - "fully distributed optimal channel assignment for open spectrum access"

Connected through hyperedge HE-5 (induced by source paper "an information theoretic analysis of the gaussian multicast channel with interactive user cooperation"):
  with members:
    - "enhancing multiuser mimo through opportunistic d2d cooperation"
    - "on the achievable rates of multihop virtual full duplex relay channels"
    - "noisy network coding with partial df"
    - "a survey on device to device communication in cellular networks"
    - "massive mimo multicasting in noncooperative cellular networks"
    - "spectrum sharing for device to device communication in cellular networks"
    - "modeling analysis and optimization of multicast device to device transmissions"
    - "short message noisy network coding with rate splitting"

Connected through hyperedge HE-6 (induced by source paper "study of joint mmse consensus and relay selection algorithms for distributed beamforming"):
  with members:
    - "widely linear precoding for large scale mimo with iqi algorithms and performance analysis"
    - "robust adaptive beamforming using a low complexity shrinkage based mismatch estimation algorithm"
    - "direction finding algorithms based on joint iterative subspace optimization"
    - "multi branch tomlinson harashima precoding design for mu mimo systems theory and algorithms"
    - "a new class of upper bounds on the log partition function"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-7 (induced by source paper "study of joint msinr and relay selection algorithms for distributed beamforming"):
  with members:
    - "robust adaptive beamforming based on low rank and cross correlation techniques"
    - "robust adaptive beamforming using a low complexity shrinkage based mismatch estimation algorithm"
    - "direction finding algorithms based on joint iterative subspace optimization"
    - "adaptive distributed space time coding based on adjustable code matrices for cooperative mimo relaying systems"

Connected through hyperedge HE-8 (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"

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)