Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Reusing Pilots Among Interfering Cells in Massive MIMO   Pilot contamination, caused by the reuse of pilots among interfering cells,
remains as a significant obstacle that limits the performance of massive
multi-input multi-output antenna systems. To handle this problem, less
aggressive reuse of pilots involving allocation of additional pilots for
interfering users is closely examined in this paper. Hierarchical pilot reuse
methods are proposed, which effectively mitigate pilot contamination and
increase the net throughput of the system. Among the suggested hierarchical
pilot reuse schemes, the optimal way of assigning pilots to different users is
obtained in a closed-form solution which maximizes the net sum-rate in a given
coherence time. Simulation results confirm that when the ratio of the channel
coherence time to the number of users in each cell is sufficiently large, less
aggressive reuse of pilots yields significant performance advantage relative to
the case where all cells reuse the same pilot set.

22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph