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: "fundamental limits of cooperation"
  Abstract: Cooperation is viewed as a key ingredient for interference management in wireless systems. This paper shows that cooperation has fundamental limitations. The main result is that even full cooperation between transmitters cannot in general change an interference-limited network to a noise-limited network. The key idea is that there exists a spectral efficiency upper bound that is independent of the transmit power. First, a spectral efficiency upper bound is established for systems that rely on pilot-assisted channel estimation; in this framework, cooperation is shown to be possible only within clusters of limited size, which are subject to out-of-cluster interference whose power scales with that of the in-cluster signals. Second, an upper bound is also shown to exist when cooperation is through noncoherent communication; thus, the spectral efficiency limitation is not a by-product of the reliance on pilot-assisted channel estimation. Consequently, existing literature that routinely assumes the high-power spectral efficiency scales with the log of the transmit power provides only a partial characterization. The complete characterization proposed in this paper subdivides the high-power regime into a degrees-of-freedom regime, where the scaling with the log of the transmit power holds approximately, and a saturation regime, where the spectral efficiency hits a ceiling that is independent of the power. Using a cellular system as an example, it is demonstrated that the spectral efficiency saturates at power levels of operational relevance.

Connected through hyperedge HE-1 (induced by source paper "area spectral efficiency and sinr scaling laws in multi antenna cellular networks"):
  with members:
    - "scaling laws of dense multi antenna cellular networks"
    - "sinr and throughput of dense cellular networks with stretched exponential path loss"
    - "a unified asymptotic analysis of area spectral efficiency in ultradense cellular networks"
    - "performance limits of network densification"
    - "modeling and analysis of cellular networks using stochastic geometry a tutorial"
    - "performance impact of base station antenna heights in dense cellular networks"
    - "a primer on cellular network analysis using stochastic geometry"
    - "scaling laws for ergodic spectral efficiency in mimo poisson networks"

Connected through hyperedge HE-2 (induced by source paper "joint user selection power allocation and precoding design with imperfect csit for multi cell mu mimo downlink systems"):
  with members:
    - "optimal pilot and payload power control in single cell massive mimo systems"
    - "on the capacity of cloud radio access networks with oblivious relaying"
    - "on the ergodic rate lower bounds with applications to massive mimo"
    - "massive mimo with imperfect channel covariance information"
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "cell free massive mimo versus small cells"
    - "a rate splitting strategy for massive mimo with imperfect csit"

Connected through hyperedge HE-3 (induced by source paper "provisioning energy efficiency and qos for multi carrier comp with limited feedback"):
  with members:
    - "performance analysis and optimization for interference alignment over mimo interference channels with limited feedback"
    - "what will 5g be"
    - "interference coordination random clustering and adaptive limited feedback"
    - "group sparse beamforming for green cloud ran"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "downlink sdma with limited feedback in interference limited wireless networks"
    - "base station cooperation with feedback optimization a large system analysis"

Connected through hyperedge HE-4 (induced by source paper "ubiquitous cell free massive mimo communications"):
  with members:
    - "downlink training in cell free massive mimo a blessing in disguise"
    - "scalability aspects of cell free massive mimo"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"
    - "fog massive mimo a user centric seamless hot spot architecture"
    - "enhancing favorable propagation in cell free massive mimo through spatial user grouping"
    - "on the total energy efficiency of cell free massive mimo"
    - "channel hardening and favorable propagation in cell free massive mimo with stochastic geometry"
    - "cell free massive mimo versus small cells"

Connected through hyperedge HE-5 (induced by source paper "local partial zero forcing precoding for cell free massive mimo"):
  with members:
    - "scalability aspects of cell free massive mimo"
    - "ubiquitous cell free massive mimo communications"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"
    - "downlink spectral efficiency of cell free massive mimo with full pilot zero forcing"
    - "cell free massive mimo with limited backhaul"
    - "on the total energy efficiency of cell free massive mimo"
    - "cell free massive mimo versus small cells"
    - "reciprocity calibration for massive mimo proposal modeling and validation"

Connected through hyperedge HE-6 (induced by source paper "techniques for system information broadcast in cell free massive mimo"):
  with members:
    - "ubiquitous cell free massive mimo communications"
    - "on the total energy efficiency of cell free massive mimo"
    - "modeling and analysis of cellular networks using stochastic geometry a tutorial"
    - "optimal pilot and payload power control in single cell massive mimo systems"
    - "channel hardening and favorable propagation in cell free massive mimo with stochastic geometry"
    - "performance of in band transmission of system information in massive mimo systems"
    - "energy efficiency in cell free massive mimo with zero forcing precoding design"
    - "cell free massive mimo versus small cells"

Connected through hyperedge HE-7 (induced by source paper "scalability aspects of cell free massive mimo"):
  with members:
    - "ubiquitous cell free massive mimo communications"
    - "on the total energy efficiency of cell free massive mimo"
    - "cell free massive mimo versus small cells"

Connected through hyperedge HE-8 (induced by source paper "intelligent scheduling and power control for multimedia transmission in 5g comp systems a dynamic bargaining game"):
  with members:
    - "power and channel allocation for non orthogonal multiple access in 5g systems tractability and computation"
    - "towards 1 gbps ue in cellular systems understanding ultra dense small cell deployments"

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)