human: Given a node-centered hypergraph: <hypergraph>, where nodes represent authors and hyperedges represent groups of authors who co-authored the same paper.

Details of the hypergraph:
Center node: "Efficient power allocation for decentralized distributed space-time block coding"
  Abstract: In this paper, we propose two ad-hoc, yet efficient, power allocation strategies for a decentralized distributed space-time block coding (Dis-STBC) system where knowledge about the channel state information (CSI) is not available at the transmitter(s). The first is an open-loop strategy which requires no control signaling; the second is a feedback-assisted strategy which requires some control signaling, but which can achieve better power-efficiency. Focusing on a particular decentralized Dis-STBC scheme (m-group), the asymptotic outage probability is derived and the power-efficiency advantages of the proposed strategies over a uniform-power strategy are illustrated by evaluating the outage and link failure probabilities.

Connected through hyperedge HE-1 (induced by source paper "Power-efficient relay selection in cooperative networks using decentralized distributed space-time block coding"):
  with members:
    (none)

Question: Please tell me which research area the center author belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Mathematics