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: "channel hardening and favorable propagation in cell free massive mimo with stochastic geometry"
  Abstract: Cell-Free (CF) Massive MIMO is an alternative topology for Massive MIMO networks, where a large number of single-antenna access points (APs) are distributed over the coverage area. There are no cells but all users are jointly served by the APs using network MIMO methods. In prior work, it has been claimed that CF Massive MIMO inherits the basic properties of cellular Massive MIMO, namely channel hardening and favorable propagation. In this paper, we evaluate if one can rely on these properties when having a realistic stochastic AP deployment. Our results show that the level of channel hardening depends strongly on the propagation environment and there is generally little hardening, except when the pathloss exponent is small. We further show that using 5--10 antennas per AP, instead of one, we can greatly improve the hardening. The level of favorable propagation is affected by the propagation environment and by the distance between the users, where only spatially well separated users exhibit favorable propagation. The conclusion is that we cannot rely on channel hardening and favorable propagation when analyzing and designing CF Massive MIMO networks, but we need to use achievable rate expressions and resource allocation schemes that work well in the absence of these properties. Some options are described in this paper.

Connected through hyperedge HE-1 (induced by source paper "multiple antenna technologies for beyond 5g"):
  with members:
    - "intelligent reflecting surface versus decode and forward how large surfaces are needed to beat relaying"
    - "robust trajectory and resource allocation design for secure uav aided communications"
    - "a new look at cell free massive mimo making it practical with dynamic cooperation"
    - "scalability aspects of cell free massive mimo"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "robust and secure wireless communications via intelligent reflecting surfaces"
    - "channel estimation for intelligent reflecting surface assisted multiuser communications framework algorithms and analysis"
    - "resource allocation for secure irs assisted multiuser miso systems"

Connected through hyperedge HE-2 (induced by source paper "scalable cell free massive mimo systems"):
  with members:
    - "a new look at cell free massive mimo making it practical with dynamic cooperation"
    - "scalability aspects of cell free massive mimo"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"
    - "covariance matrix estimation for massive mimo"
    - "massive mimo in sub 6 ghz and mmwave physical practical and use case differences"
    - "on the performance of backhaul constrained cell free massive mimo with linear receivers"
    - "fog massive mimo a user centric seamless hot spot architecture"
    - "covariance matrix estimation in massive mimo"

Connected through hyperedge HE-3 (induced by source paper "making cell free massive mimo competitive with mmse processing and centralized implementation"):
  with members:
    - "ubiquitous cell free massive mimo communications"
    - "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"
    - "few bit csi acquisition for centralized cell free massive mimo with spatial correlation"
    - "can massive mimo support uplink intensive applications"
    - "on the performance of backhaul constrained cell free massive mimo with linear receivers"
    - "massive mimo has unlimited capacity"
    - "performance of cell free massive mimo systems with mmse and lsfd receivers"
    - "on the total energy efficiency of cell free massive mimo"

Connected through hyperedge HE-4 (induced by source paper "rate analysis of cell free massive mimo noma with three linear precoders"):
  with members:
    - "what role can noma play in massive mimo"
    - "ubiquitous cell free massive mimo communications"
    - "interplay between noma and other emerging technologies a survey"
    - "downlink spectral efficiency of cell free massive mimo with full pilot zero forcing"
    - "signal processing for mimo noma present and future challenges"
    - "on the total energy efficiency of cell free massive mimo"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "capacity comparison between mimo noma and mimo oma with multiple users in a cluster"

Connected through hyperedge HE-5 (induced by source paper "edge computing enabled cell free massive mimo systems"):
  with members:
    - "mobile edge computing enabled heterogeneous networks"
    - "fog massive mimo a user centric seamless hot spot architecture"
    - "joint energy minimization and resource allocation in c ran with mobile cloud"
    - "a survey on mobile edge computing the communication perspective"
    - "energy efficient resource allocation for mobile edge computation offloading"
    - "collaborative mobile edge computing in 5g networks new paradigms scenarios and challenges"
    - "power delay tradeoff in multi user mobile edge computing systems"
    - "cell free massive mimo uniformly great service for everyone"

Connected through hyperedge HE-6 (induced by source paper "dynamic resource allocation in co located and cell free massive mimo"):
  with members:
    - "dynamic scheduling and power control in uplink massive mimo with random data arrivals"
    - "ubiquitous cell free massive mimo communications"
    - "large scale fading decoding in cellular massive mimo systems with spatially correlated channels"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"
    - "dynamic power control for packets with deadlines"
    - "performance of cell free massive mimo systems with mmse and lsfd receivers"
    - "optimal pilot and payload power control in single cell massive mimo systems"
    - "ultra reliable and low latency communication in mmwave enabled massive mimo networks"

Connected through hyperedge HE-7 (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"
    - "cell free massive mimo versus small cells"
    - "how much do downlink pilots improve cell free massive mimo"

Connected through hyperedge HE-8 (induced by source paper "transmission strategies for cell free massive mimo with limited capacity fronthaul links"):
  with members:
    - "cell free massive mimo with limited backhaul"
    - "spectral and energy efficiency of cell free massive mimo systems with hardware impairments"
    - "spectral efficiency of multipair massive mimo two way relaying with hardware impairments"
    - "on the total energy efficiency of cell free massive mimo"
    - "energy efficiency in cell free massive mimo with zero forcing precoding design"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "cell free massive mimo versus small cells"
    - "compute and forward in cell free massive mimo great performance with low backhaul load"

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)