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 for massive mimo systems with intra cell pilot contamination"
  Abstract: Massive MIMO systems, where the base stations are equipped with hundreds of antenna elements, are an attractive way to attain unprecedented spectral efficiency in future wireless networks. In the "classical" massive MIMO setting, the terminals are assumed fully loaded and a main impairment to the performance comes from the inter-cell pilot contamination, i.e., interference from terminals in neighboring cells using the same pilots as in the home cell. However, when the terminals are active intermittently, it is viable to avoid inter-cell contamination by pre-allocation of pilots, while same-cell terminals use random access to select the allocated pilot sequences. This leads to the problem of intra-cell pilot contamination. We propose a framework for random access in massive MIMO networks and derive new uplink sum rate expressions that take intra-cell pilot collisions, intermittent terminal activity, and interference into account. We use these expressions to optimize the terminal activation probability and pilot length.

Connected through hyperedge HE-1 (induced by source paper "efficient pilot allocation for urllc traffic in 5g industrial iot networks"):
  with members:
    - "channel hardening in massive mimo a measurement based analysis"
    - "sparse signal processing for grant free massive connectivity a future paradigm for random access protocols in the internet of things"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for crowd scenarios a solution based on random access"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-2 (induced by source paper "towards massive connectivity support for scalable mmtc communications in 5g networks"):
  with members:
    - "a random access protocol for pilot allocation in crowded massive mimo systems"
    - "compressive coded random access for massive mtc traffic in 5g systems"
    - "reliable and efficient access for alarm initiated and regular m2m traffic in ieee 802 11ah systems"
    - "massive machine type communication mmtc access with integrated authentication"
    - "reliable recovery of hierarchically sparse signals and application in machine type communications"
    - "pulse shaped ofdm for 5g systems"
    - "coded pilot access a random access solution for massive mimo systems"
    - "compressive random access using a common overloaded control channel"

Connected through hyperedge HE-3 (induced by source paper "a random access protocol for pilot allocation in crowded massive mimo systems"):
  with members:
    - "random access in uplink massive mimo systems how to exploit asynchronicity and excess antennas"
    - "massive mimo ten myths and one critical question"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for crowd scenarios a solution based on random access"
    - "three practical aspects of massive mimo intermittent user activity pilot synchronism and asymmetric deployment"
    - "coded random access applying codes on graphs to design random access protocols"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "coded random access how coding theory helps to build random access protocols"

Connected through hyperedge HE-4 (induced by source paper "random pilot and data access in massive mimo for machine type communications"):
  with members:
    - "a random access protocol for pilot allocation in crowded massive mimo systems"
    - "random access in uplink massive mimo systems how to exploit asynchronicity and excess antennas"
    - "coded pilot access a random access solution for massive mimo systems"
    - "massive mimo ten myths and one critical question"
    - "towards very large aperture massive mimo a measurement based study"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for crowd scenarios a solution based on random access"
    - "three practical aspects of massive mimo intermittent user activity pilot synchronism and asymmetric deployment"

Connected through hyperedge HE-5 (induced by source paper "random access protocols for massive mimo"):
  with members:
    - "a random access protocol for pilot allocation in crowded massive mimo systems"
    - "rrh based massive mimo with on the fly pilot contamination control"
    - "random access in uplink massive mimo systems how to exploit asynchronicity and excess antennas"
    - "coded pilot access a random access solution for massive mimo systems"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "coded random access applying codes on graphs to design random access protocols"
    - "coded random access how coding theory helps to build random access protocols"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-6 (induced by source paper "coded pilot access a random access solution for massive mimo systems"):
  with members:
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for crowd scenarios a solution based on random access"
    - "coded random access how coding theory helps to build random access protocols"
    - "exploiting capture effect in frameless aloha for massive wireless random access"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "a coordinated approach to channel estimation in large scale multiple antenna systems"
    - "frameless aloha protocol for wireless networks"

Connected through hyperedge HE-7 (induced by source paper "a high throughput pilot allocation for m2m communication in crowded massive mimo systems"):
  with members:
    - "massive mimo ten myths and one critical question"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for crowd scenarios a solution based on random access"
    - "performance analysis of split preamble ran over load protocol for m2m communications in cellular networks"
    - "aspects of favorable propagation in massive mimo"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"

Connected through hyperedge HE-8 (induced by source paper "random access in uplink massive mimo systems how to exploit asynchronicity and excess antennas"):
  with members:
    - "massive mimo ten myths and one critical question"
    - "random access protocol for massive mimo strongest user collision resolution sucr"
    - "massive mimo for crowd scenarios a solution based on random access"
    - "massive mimo for next generation wireless systems"

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)