8,157 research outputs found
Distributed Channel Quantization for Two-User Interference Networks
We introduce conferencing-based distributed channel quantizers for two-user
interference networks where interference signals are treated as noise. Compared
with the conventional distributed quantizers where each receiver quantizes its
own channel independently, the proposed quantizers allow multiple rounds of
feedback communication in the form of conferencing between receivers. We take
the network outage probabilities of sum rate and minimum rate as performance
measures and consider quantizer design in the transmission strategies of time
sharing and interference transmission. First, we propose distributed quantizers
that achieve the optimal network outage probability of sum rate for both time
sharing and interference transmission strategies with an average feedback rate
of only two bits per channel state. Then, for the time sharing strategy, we
propose a distributed quantizer that achieves the optimal network outage
probability of minimum rate with finite average feedback rate; conventional
quantizers require infinite rate to achieve the same performance. For the
interference transmission strategy, a distributed quantizer that can approach
the optimal network outage probability of minimum rate closely is also
proposed. Numerical simulations confirm that our distributed quantizers based
on conferencing outperform the conventional ones.Comment: 30 pages, 4 figure
Limited Feedback Design for Interference Alignment on MIMO Interference Networks with Heterogeneous Path Loss and Spatial Correlations
Interference alignment is degree of freedom optimal in K -user MIMO
interference channels and many previous works have studied the transceiver
designs. However, these works predominantly focus on networks with perfect
channel state information at the transmitters and symmetrical interference
topology. In this paper, we consider a limited feedback system with
heterogeneous path loss and spatial correlations, and investigate how the
dynamics of the interference topology can be exploited to improve the feedback
efficiency. We propose a novel spatial codebook design, and perform dynamic
quantization via bit allocations to adapt to the asymmetry of the interference
topology. We bound the system throughput under the proposed dynamic scheme in
terms of the transmit SNR, feedback bits and the interference topology
parameters. It is shown that when the number of feedback bits scales with SNR
as C_{s}\cdot\log\textrm{SNR}, the sum degrees of freedom of the network are
preserved. Moreover, the value of scaling coefficient C_{s} can be
significantly reduced in networks with asymmetric interference topology.Comment: 30 pages, 6 figures, accepted by IEEE transactions on signal
processing in Feb. 201
Interference Alignment with Limited Feedback on Two-cell Interfering Two-User MIMO-MAC
In this paper, we consider a two-cell interfering two-user multiple-input
multiple-output multiple access channel (MIMO-MAC) with limited feedback. We
first investigate the multiplexing gain of such channel when users have perfect
channel state information at transmitter (CSIT) by exploiting an interference
alignment scheme. In addition, we propose a feedback framework for the
interference alignment in the limited feedback system. On the basis of the
proposed feedback framework, we analyze the rate gap loss and it is shown that
in order to keep the same multiplexing gain with the case of perfect CSIT, the
number of feedback bits per receiver scales as , where and denote the number of
transmit antennas and a constant, respectively. Throughout the simulation
results, it is shown that the sum-rate performance coincides with the derived
results.Comment: 6 pages, 2 figures, Submitted ICC 201
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