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: "towards the secrecy capacity of the gaussian mimo wire tap channel the 2 2 1 channel"
  Abstract: We find the secrecy capacity of the 2-2-1 Gaussian MIMO wiretap channel, which consists of a transmitter and a receiver with two antennas each, and an eavesdropper with a single antenna. We determine the secrecy capacity of this channel by proposing an achievable scheme and then developing a tight upper bound that meets the proposed achievable secrecy rate. We show that, for this channel, Gaussian signalling in the form of beam-forming is optimal, and no pre-processing of information is necessary.

Connected through hyperedge HE-1 (induced by source paper "interplay between noma and other emerging technologies a survey"):
  with members:
    - "secure relaying in non orthogonal multiple access trusted and untrusted scenarios"
    - "securing downlink massive mimo noma networks with artificial noise"
    - "lens based millimeter wave reconfigurable antenna noma"
    - "what role can noma play in massive mimo"
    - "noma an information theoretic perspective"
    - "joint power and time allocation for noma mec offloading"
    - "multi beam noma for hybrid mmwave systems"
    - "exploiting full half duplex user relaying in noma systems"

Connected through hyperedge HE-2 (induced by source paper "enabling security and high energy efficiency in the internet of things with massive mimo hybrid precoding"):
  with members:
    - "joint optimization of computation and communication power in multi user massive mimo systems"
    - "secure massive mimo systems with limited rf chains"
    - "energy efficiency optimization of 5g radio frequency chain systems"
    - "physical layer security in heterogeneous cellular networks"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "jamming aided secure communication in massive mimo rician channels"
    - "on the secrecy outage capacity of physical layer security in large scale mimo relaying systems with imperfect csi"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"

Connected through hyperedge HE-3 (induced by source paper "a rotation based method for precoding in gaussian mimome channels"):
  with members:
    - "noma an information theoretic perspective"
    - "optimal beamforming for gaussian mimo wiretap channels with two transmit antennas"
    - "optimal signaling for secure communications over gaussian mimo wiretap channels"
    - "an algorithm for global maximization of secrecy rates in gaussian mimo wiretap channels"
    - "full rank solutions for the mimo gaussian wiretap channel with an average power constraint"
    - "cooperative jamming for secure communications in mimo relay networks"
    - "transmitter optimization for achieving secrecy capacity in gaussian mimo wiretap channels"
    - "the secrecy capacity of the mimo wiretap channel"

Connected through hyperedge HE-4 (induced by source paper "the secrecy capacity of gaussian mimo channels with finite memory full version"):
  with members:
    - "on the capacity of narrowband plc channels"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "full rank solutions for the mimo gaussian wiretap channel with an average power constraint"
    - "source channel coding theorems for the multiple access relay channel"
    - "private broadcasting over independent parallel channels"
    - "for the grid and through the grid the role of power line communications in the smart grid"
    - "secured communication over frequency selective fading channels a practical vandermonde precoding"
    - "the capacity region of the degraded finite state broadcast channel"

Connected through hyperedge HE-5 (induced by source paper "secrecy rate of distributed cooperative mimo in the presence of multi antenna eavesdropper"):
  with members:
    - "cooperative secure transmission by exploiting social ties in random networks"
    - "on secrecy performance of antenna selection aided mimo systems against eavesdropping"
    - "optimal signaling for secure communications over gaussian mimo wiretap channels"
    - "optimization of code rates in sisome wiretap channels"
    - "secure and green swipt in distributed antenna networks with limited backhaul capacity"
    - "power allocation in mimo wiretap channel with statistical csi and finite alphabet input"
    - "on secrecy capacity of fast fading mimome wiretap channels with statistical csit"
    - "full rank solutions for the mimo gaussian wiretap channel with an average power constraint"

Connected through hyperedge HE-6 (induced by source paper "optimal beamforming for gaussian mimo wiretap channels with two transmit antennas"):
  with members:
    - "optimal signaling for secure communications over gaussian mimo wiretap channels"
    - "an algorithm for global maximization of secrecy rates in gaussian mimo wiretap channels"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "full rank solutions for the mimo gaussian wiretap channel with an average power constraint"
    - "on secrecy rate analysis of mimo wiretap channels driven by finite alphabet input"
    - "secure transmission with multiple antennas ii the mimome wiretap channel"
    - "transmitter optimization for achieving secrecy capacity in gaussian mimo wiretap channels"
    - "the secrecy capacity of the mimo wiretap channel"

Connected through hyperedge HE-7 (induced by source paper "on the achievable secrecy diversity of cooperative networks with untrusted relays"):
  with members:
    - "nonlinear interference alignment in a one dimensional space"
    - "real interference alignment exploiting the potential of single antenna systems"
    - "interference assisted secret communication"
    - "strong secrecy from channel resolvability"
    - "cooperation with an untrusted relay a secrecy perspective"
    - "the secrecy capacity region of the gaussian mimo multi receiver wiretap channel"

Connected through hyperedge HE-8 (induced by source paper "physical layer security in heterogeneous cellular networks"):
  with members:
    - "optimal power allocation for artificial noise under imperfect csi against spatially random eavesdroppers"
    - "secrecy transmit beamforming for heterogeneous networks"
    - "physical layer security in downlink multi antenna cellular networks"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "throughput and energy efficiency analysis of small cell networks with multi antenna base stations"
    - "enhancing secrecy with multi antenna transmission in wireless ad hoc networks"
    - "physical layer security in cellular networks a stochastic geometry approach"
    - "on the design of artificial noise aided secure multi antenna transmission in slow fading channels"

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)