human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "enhanced channel estimation in massive mimo via coordinated pilot design"):
  Abstract: Pilot contamination is a limiting factor in multicell massive multiple-input multiple-output (MIMO) systems because it can severely impair channel estimation. Prior works have suggested coordinating pilot design across cells in order to reduce the channel estimation error caused by pilot contamination. Here we propose a method for coordinated pilot design using fractional programming to minimize the weighted mean squared-error (MSE) in channel estimation. In particular, we apply the recently proposed quadratic transform to the MSE expression which allows the effect of pilot contamination to be decoupled from the MSE expression. The resulting problem reformulation enables the pilots to be optimized in closed form if they can be designed arbitrarily. When the pilots are restricted to a given set of orthogonal sequences, the pilot optimization reduces to an assignment problem which can be solved by weighted bipartite matching. Furthermore, by virtue of matrix fractional programming, we obtain an extension of the proposed method that takes correlated Rayleigh fading into account. Finally, simulations demonstrate the significant advantage of the proposed (orthogonal and nonorthogonal) pilot designs compared with the state-of-the-art methods in combating pilot contamination.

Includes members:
  Member "pilot contamination mitigation with reduced rf chains":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "power control for massive mimo systems with nonorthogonal pilots")
  Member "fractional programming for communication systems part i power control and beamforming":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "energy efficiency optimization for downlink massive mimo with statistical csit")
  Member "optimization of mimo device to device networks via matrix fractional programming a minorization maximization approach":
    also connected through other hyperedges:
      (none)
  Member "a successive optimization approach to pilot design for multi cell massive mimo systems":
    also connected through other hyperedges:
      (none)
  Member "joint pilot design and uplink power allocation in multi cell massive mimo systems":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "average sep optimal precoding for correlated massive mimo with zf detection an asymptotic analysis")
  Member "smart pilot assignment for massive mimo":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "on the pilot contamination attack in multi cell multiuser massive mimo networks")
  Member "pilot beam pattern design for channel estimation in massive mimo systems":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "secure massive mimo communication with low resolution dacs")
  Member "massive mimo for next generation wireless systems":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "joint power control and lsfd for wireless powered cell free massive mimo")

Question: Please tell me which class the source paper 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)