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: "secure communication via an untrusted non regenerative relay in fading channels"
  Abstract: We investigate a relay network where the source can potentially utilize an untrusted non-regenerative relay to augment its direct transmission of a confidential message to the destination. Since the relay is untrusted, it is desirable to protect the confidential data from it while simultaneously making use of it to increase the reliability of the transmission. We first examine the secrecy outage probability (SOP) of the network assuming a single antenna relay, and calculate the exact SOP for three different schemes: direct transmission without using the relay, conventional non-regenerative relaying, and cooperative jamming by the destination. Subsequently, we conduct an asymptotic analysis of the SOPs to determine the optimal policies in different operating regimes. We then generalize to the multi-antenna relay case and investigate the impact of the number of relay antennas on the secrecy performance. Finally, we study a scenario where the relay has only a single RF chain which necessitates an antenna selection scheme, and we show that unlike the case where all antennas are used, under certain conditions the cooperative jamming scheme with antenna selection provides a diversity advantage for the receiver. Numerical results are presented to verify the theoretical predictions of the preferred transmission policies.

Connected through hyperedge HE-1 (induced by source paper "enhancing physical layer security in af relay assisted multicarrier wireless transmission enhancing physical layer security in af relay assisted multicarrier wireless transmission"):
  with members:
    - "ofdma based df secure cooperative communication with untrusted users"
    - "enhancing physical layer security in dual hop multiuser transmission"
    - "relay placement for physical layer security a secure connection perspective"
    - "power and subcarrier allocation for physical layer security in ofdma based broadband wireless networks"

Connected through hyperedge HE-2 (induced by source paper "optimal power allocation by imperfect hardware analysis in untrusted relaying networks"):
  with members:
    - "joint relay selection and power allocation in large scale mimo systems with untrusted relays and passive eavesdroppers"
    - "optimal power allocation and secrecy sum rate in two way untrusted relaying"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "physical layer security for massive mimo systems impaired by phase noise"
    - "joint relay and jammer selection improves the physical layer security in the face of csi feedback delays"
    - "optimum wirelessly powered relaying"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"

Connected through hyperedge HE-3 (induced by source paper "on secure communication using rf energy harvesting two way untrusted relay"):
  with members:
    - "interference aided energy harvesting cognitive relaying with multiple primary transceivers"
    - "secure communication via a wireless energy harvesting untrusted relay"
    - "joint power splitting and secure beamforming design in the wireless powered untrusted relay networks"
    - "relaying protocols for wireless energy harvesting and information processing"
    - "wireless information and power transfer in two way amplify and forward relaying channels"
    - "wireless information and power transfer architecture design and rate energy tradeoff"
    - "robust beamforming for wireless information and power transmission"
    - "construction of wiretap codes from ordinary channel codes"

Connected through hyperedge HE-4 (induced by source paper "secret key generation through a relay"):
  with members:
    - "common randomness and key generation with limited interaction"
    - "on secure source coding with side information at the encoder"
    - "common information and secret key capacity"
    - "strongly secure communications over the two way wiretap channel"
    - "rate regions of secret key sharing in a new source model"
    - "cooperation with an untrusted relay a secrecy perspective"
    - "secret key agreement from correlated gaussian sources by rate limited public communication"
    - "multiterminal source coding with complementary delivery"

Connected through hyperedge HE-5 (induced by source paper "transmitter optimization in slow fading miso wiretap channel"):
  with members:
    - "on the design of artificial noise aided secure multi antenna transmission in slow fading channels"
    - "the secrecy capacity of the mimo wiretap channel"
    - "mutual information and minimum mean square error in gaussian channels"

Connected through hyperedge HE-6 (induced by source paper "enhancing physical layer security in dual hop multiuser transmission"):
  with members:
    - "relay placement for physical layer security a secure connection perspective"
    - "power and subcarrier allocation for physical layer security in ofdma based broadband wireless networks"

Connected through hyperedge HE-7 (induced by source paper "secure communication via a wireless energy harvesting untrusted relay"):
  with members:
    - "rf based energy harvesting in decode and forward relaying systems ergodic and outage capacities"
    - "relay selection for wireless communications against eavesdropping a security reliability trade off perspective"
    - "secrecy wireless information and power transfer in fading wiretap channel"
    - "wireless powered relays in cooperative communications time switching relaying protocols and throughput analysis"
    - "distributed power splitting for swipt in relay interference channels using game theory"
    - "interference assisted wireless energy harvesting in cognitive relay network with multiple primary transceivers"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "wireless networks with rf energy harvesting a contemporary survey"

Connected through hyperedge HE-8 (induced by source paper "apply artificial noise to secure fading relay networks a ser based approach"):
  with members:
    - "imbalanced beamforming by a multi antenna source for secure utilization of an untrusted relay"
    - "jamming games in the mimo wiretap channel with an active eavesdropper"
    - "new results on multiple input multiple output broadcast channels with confidential messages"
    - "secrecy sum rates for multi user mimo regularized channel inversion precoding"
    - "a tutorial on the optimization of amplify and forward mimo relay systems"
    - "physical layer network coding tutorial survey and beyond"
    - "solutions for the mimo gaussian wiretap channel with a cooperative jammer"
    - "secure transmission with artificial noise over fading channels achievable rate and optimal power allocation"

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)