Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Channel Feedback for Reconfigurable Intelligent Surface Assisted
  Wireless Communications   Reconfigurable intelligent surface (RIS) has received widespread attention
owing to the superiority of changing the wireless propagation environment
intelligently. Channel feedback is essential in frequency division duplex (FDD)
RIS-assisted wireless communications, since the downlink channel state
information (CSI) needs to be acquired by the base station (BS) from the user
equipment (UE) for the joint beamforming at the BS and the RIS. In this paper,
we exploit the single-structured sparsity of RIS channel, which means that the
sparse angular-domain channels of different users share the same structured
sparsity only in the column dimension, but not in the row dimension. Based on
this characteristic, we propose a dimension reduced channel feedback scheme
with the low overhead. Specifically, the downlink CSI can be expressed with the
structured information and unstructured information. The structured information
of the multi-user channels can be fed back to the BS only by one user according
to the single-structured sparsity, then the unstructured information can be fed
back with a fairly low overhead by different users, respectively. Moreover, by
utilizing the angle coherence time, the per-user overhead can be reduced
further, while the near-optimal performance can still be guaranteed. Simulation
results show that, the proposed scheme can reduce the channel feedback overhead
by 80% compared to the conventional method.

10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn