Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatial Resource Allocation for Spectrum Reuse in Unlicensed LTE Systems   In this paper, we study how to reuse the unlicensed spectrum in LTE-U systems
while guaranteeing harmonious coexistence between the LTE-U and Wi-Fi systems.
For a small cell with multiple antennas at the base station (SBS), some spatial
degrees of freedom (DoFs) are used to serve small cell users (SUEs) while the
rest are employed to mitigate the interference to the Wi-Fi users by applying
zero-forcing beamforming (ZFBF). As a result, the LTE-U and Wi-Fi throughput
can be balanced by carefully allocating the spatial DoFs. Due to the channel
state information (CSI) estimation and feedback errors, ZFBF cannot eliminate
the interference completely. We first analyze the residual interference among
SUEs, called intra-RAT interference, and the interference to the Wi-Fi users,
called inter-RAT interference after ZFBF, due to imperfect CSI. Based on the
analysis, we derive the throughputs of the small cell and the Wi-Fi systems,
respectively. Accordingly, a spatial DoF allocation scheme is proposed to
balance the throughput between the small cell and the Wi-Fi systems. Our
theoretical analysis and the proposed scheme are verified by simulation
results.

28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph