Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Joint Bi-Directional Training of Nonlinear Precoders and Receivers in
  Cellular Networks   Joint optimization of nonlinear precoders and receive filters is studied for
both the uplink and downlink in a cellular system. For the uplink, the base
transceiver station (BTS) receiver implements successive interference
cancellation, and for the downlink, the BTS station pre-compensates for the
interference with Tomlinson-Harashima precoding (THP). Convergence of
alternating optimization of receivers and transmitters in a single cell is
established when filters are updated according to a minimum mean squared error
(MMSE) criterion, subject to appropriate power constraints. Adaptive algorithms
are then introduced for updating the precoders and receivers in the absence of
channel state information, assuming time-division duplex transmissions with
channel reciprocity. Instead of estimating the channels, the filters are
directly estimated according to a least squares criterion via bi-directional
training: Uplink pilots are used to update the feedforward and feedback
filters, which are then used as interference pre-compensation filters for
downlink training of the mobile receivers. Numerical results show that
nonlinear filters can provide substantial gains relative to linear filters with
limited forward-backward iterations.

26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex