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: "random access protocols for massive mimo"
  Abstract: 5G wireless networks are expected to support new services with stringent requirements on data rates, latency and reliability. One novel feature is the ability to serve a dense crowd of devices, calling for radically new ways of accessing the network. This is the case in machine-type communications, but also in urban environments and hotspots. In those use cases, the high number of devices and the relatively short channel coherence interval do not allow per-device allocation of orthogonal pilot sequences. This article motivates the need for random access by the devices to pilot sequences used for channel estimation, and shows that Massive MIMO is a main enabler to achieve fast access with high data rates, and delay-tolerant access with different data rate levels. Three pilot access protocols along with data transmission protocols are described, fulfilling different requirements of 5G services.

Connected through hyperedge HE-1 (induced by source paper "online estimation and adaptation for random access with successive interference cancellation"):
  with members:
    - "maximum sum rate of slotted aloha with successive interference cancellation"
    - "massive non orthogonal multiple access for cellular iot potentials and limitations"
    - "coded slotted aloha a graph based method for uncoordinated multiple access"
    - "aloha random access that operates as a rateless code"
    - "graph based random access for the collision channel without feedback capacity bound"

Connected through hyperedge HE-2 (induced by source paper "ml estimation and map estimation for device activities in grant free random access with interference"):
  with members:
    - "improved scaling law for activity detection in massive mimo systems"
    - "sparse activity detection for massive connectivity"

Connected through hyperedge HE-3 (induced by source paper "massive mimo for internet of things iot connectivity"):
  with members:
    - "massive mimo unsourced random access"
    - "ultrareliable and low latency communication techniques for tactile internet services"
    - "non stationarities in extra large scale massive mimo"
    - "ubiquitous cell free massive mimo communications"
    - "sparcs for unsourced random access"
    - "management of network slicing in 5g radio access networks functional framework and information models"
    - "grant free massive mtc enabled massive mimo a compressive sensing approach"
    - "massive mimo for ultra reliable communications with constellations for dual coherent noncoherent detection"

Connected through hyperedge HE-4 (induced by source paper "grant free massive mtc enabled massive mimo a compressive sensing approach"):
  with members:
    - "massive connectivity with massive mimo part i device activity detection and channel estimation"
    - "a novel receiver design with joint coherent and non coherent processing"
    - "user activity detection in massive random access compressed sensing vs coded slotted aloha"
    - "device activity and embedded information bit detection using amp in massive mimo"
    - "random pilot and data access in massive mimo for machine type communications"
    - "compressive sensing based multiuser detector for the large scale sm mimo uplink"
    - "design and performance analysis of noncoherent detection systems with massive receiver arrays"
    - "massive machine type communications in 5g physical and mac layer solutions"

Connected through hyperedge HE-5 (induced by source paper "multiple preambles for high success rate of grant free random access with massive mimo"):
  with members:
    - "grant free massive mtc enabled massive mimo a compressive sensing approach"
    - "success probability of grant free random access with massive mimo"
    - "sparse signal processing for grant free massive connectivity a future paradigm for random access protocols in the internet of things"
    - "a random access protocol for pilot allocation in crowded massive mimo systems"
    - "frameless aloha with reliability latency guarantees"
    - "random pilot and data access in massive mimo for machine type communications"
    - "a high throughput pilot allocation for m2m communication in crowded massive mimo systems"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-6 (induced by source paper "success probability of grant free random access with massive mimo"):
  with members:
    - "massive multiple access based on superposition raptor codes for cellular m2m communications"
    - "random pilot and data access in massive mimo for machine type communications"
    - "random access preamble design and detection for 3gpp narrowband iot systems"
    - "rrh based massive mimo with on the fly pilot contamination control"
    - "a high throughput pilot allocation for m2m communication in crowded massive mimo systems"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for next generation wireless systems"
    - "emerging technologies and research challenges for 5g wireless networks"

Connected through hyperedge HE-7 (induced by source paper "efficient c ran random access for iot devices learning links via recommendation systems"):
  with members:
    - "compressive channel estimation and multi user detection in c ran"
    - "a novel alternative to cloud ran for throughput densification coded pilots and fast user packet scheduling at remote radio heads"
    - "user activity detection in massive random access compressed sensing vs coded slotted aloha"
    - "rrh based massive mimo with on the fly pilot contamination control"
    - "directional training and fast sector based processing schemes for mmwave channels"
    - "user association and interference management in massive mimo hetnets"
    - "optimal user cell association for massive mimo wireless networks"
    - "analysis of blockage effects on urban cellular networks"

Connected through hyperedge HE-8 (induced by source paper "humans and machines can be jointly spatially multiplexed by massive mimo"):
  with members:
    - "random pilot and data access in massive mimo for machine type communications"
    - "multi cell multiuser massive mimo networks user capacity analysis and pilot design"
    - "long range communications in unlicensed bands the rising stars in the iot and smart city scenarios"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"

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)