2,365 research outputs found
Interference Alignment in MIMO Interference Channels using SDP Relaxation
Nowadays, providing higher data rate is a momentous goal for wireless
communications systems. Interference is one of the important obstacles to reach
this purpose. Interference alignment is a management technique that align
interference from other transmitters in the least possible dimension subspace
at each receiver and as a result, provide the remaining dimensions for free
interference signal. An uncoordinated interference is an example of
interference which cannot be aligned coordinately with interference from
coordinated part and consequently, the performance of interference alignment
approaches is degraded. In this paper, we propose two rank minimization methods
to enhance the performance of interference alignment in the presence of
uncoordinated interference sources. Firstly, a new objective function is chosen
then, a new class of convex relaxation is proposed with respect to the
uncoordinated interference which leads to decrease the optimal value of our
optimization problem. Moreover, we use schatten-p-norm as surrogate of rank
function and we implement iteratively reweighted algorithm to solve
optimization problem. In addition, we apply our proposed methods to mitigate
interference in relay-aided MIMO interference channel, and propose a
weighted-sum method to improve the performance of interference alignment in the
amplify-and-forward relay-aided MIMO system based on the rank minimization
approach. Finally, our simulation results show that our proposed methods can
obtain considerably higher multiplexing gain and sum rate than other approaches
in the interference alignment framework and the performance of interference
alignment is improved
Low complexity sum rate maximization for single and multiple stream MIMO AF relay networks
A multiple-antenna amplify-and-forward two-hop interference network with
multiple links and multiple relays is considered. We optimize transmit
precoders, receive decoders and relay AF matrices to maximize the achievable
sum rate. Under per user and total relay sum power constraints, we propose an
efficient algorithm to maximize the total signal to total interference plus
noise ratio (TSTINR). Computational complexity analysis shows that our proposed
algorithm for TSTINR has lower complexity than the existing weighted minimum
mean square error (WMMSE) algorithm. We analyze and confirm by simulations that
the TSTINR, WMMSE and the total leakage interference plus noise (TLIN)
minimization models with per user and total relay sum power constraints can
only transmit a single data stream for each user. Thus we propose a novel
multiple stream TSTINR model with requirement of orthogonal columns for
precoders, in order to support multiple data streams and thus utilize higher
Degrees of Freedom. Multiple data streams and larger multiplexing gains are
guaranteed. Simulation results show that for single stream models, our TSTINR
algorithm outperforms the TLIN algorithm generally and outperforms WMMSE in
medium to high Signal-to-Noise-Ratio scenarios; the system sum rate
significantly benefits from multiple data streams in medium to high SNR
scenarios
Towards the Asymptotic Sum Capacity of the MIMO Cellular Two-Way Relay Channel
In this paper, we consider the transceiver and relay design for
multiple-input multiple-output (MIMO) cellular two-way relay channel (cTWRC),
where a multi-antenna base station (BS) exchanges information with multiple
multi-antenna mobile stations via a multi-antenna relay station (RS). We
propose a novel two-way relaying scheme to approach the sum capacity of the
MIMO cTWRC.Comment: submitted to TSP. Revised April 201
Beyond One-Way Communication: Degrees of Freedom of Multi-Way Relay MIMO Interference Networks
We characterize the degrees of freedom (DoF) of multi-way relay MIMO
interference networks. In particular, we consider a wireless network consisting
of 4 user nodes, each with M antennas, and one N-antenna relay node. In this
network, each user node sends one independent message to each of the other user
nodes, and there are no direct links between any two user nodes, i.e., all
communication must pass through the relay node. For this network, we show that
the symmetric DoF value per message is given by max(min(M/3,N/7),min(2M/7,N/6))
normalized by space dimensions, i.e., piecewise linear depending on M and N
alternatively. While the information theoretic DoF upper bound is established
for every M and N, the achievability relying on linear signal subspace
alignment is established in the spatially-normalized sense in general. In
addition, by deactivating 4 messages to form a two-way relay MIMO X channel, we
also present the DoF result in the similar piecewise linear type. The central
new insight to emerge from this work is the notion of inter-user signal
subspace alignment incorporating the idea of network coding, which is the key
to achieve the optimal DoF for multi-way relay interference networks. Moreover,
this work also settles the feasibility of linear interference alignment that
extends the feasibility framework from one-way to multi-way relay interference
networks.Comment: 26 pages, 3 figure
The Optimal Input Distribution for Partial Decode-and-Forward in the MIMO Relay Channel
This paper considers the partial decode-and-forward (PDF) strategy for the
Gaussian multiple-input multiple-output (MIMO) relay channel. Unlike for the
decode-and-forward (DF) strategy or point-to-point (P2P) transmission, for
which Gaussian channel inputs are known to be optimal, the input distribution
that maximizes the achievable PDF rate for the Gaussian MIMO relay channel has
remained unknown so far. For some special cases, e.g., for relay channels where
the optimal PDF strategy reduces to DF or P2P transmission, it could be deduced
that Gaussian inputs maximize the PDF rate. For the general case, however, the
problem has remained open until now. In this work, we solve this problem by
proving that the maximum achievable PDF rate for the Gaussian MIMO relay
channel is always attained by Gaussian channel inputs. Our proof relies on the
channel enhancement technique, which was originally introduced by Weingarten et
al. to derive the (private message) capacity region of the Gaussian MIMO
broadcast channel. By combining this technique with a primal decomposition
approach, we first establish that jointly Gaussian source and relay inputs
maximize the achievable PDF rate for the aligned Gaussian MIMO relay channel.
Subsequently, we use a limiting argument to extend this result from the aligned
to the general Gaussian MIMO relay channel.Comment: 23 pages, 2 figures, submitted to IEEE Transactions on Information
Theor
A Survey on MIMO Transmission with Discrete Input Signals: Technical Challenges, Advances, and Future Trends
Multiple antennas have been exploited for spatial multiplexing and diversity
transmission in a wide range of communication applications. However, most of
the advances in the design of high speed wireless multiple-input multiple
output (MIMO) systems are based on information-theoretic principles that
demonstrate how to efficiently transmit signals conforming to Gaussian
distribution. Although the Gaussian signal is capacity-achieving, signals
conforming to discrete constellations are transmitted in practical
communication systems. As a result, this paper is motivated to provide a
comprehensive overview on MIMO transmission design with discrete input signals.
We first summarize the existing fundamental results for MIMO systems with
discrete input signals. Then, focusing on the basic point-to-point MIMO
systems, we examine transmission schemes based on three most important criteria
for communication systems: the mutual information driven designs, the mean
square error driven designs, and the diversity driven designs. Particularly, a
unified framework which designs low complexity transmission schemes applicable
to massive MIMO systems in upcoming 5G wireless networks is provided in the
first time. Moreover, adaptive transmission designs which switch among these
criteria based on the channel conditions to formulate the best transmission
strategy are discussed. Then, we provide a survey of the transmission designs
with discrete input signals for multiuser MIMO scenarios, including MIMO uplink
transmission, MIMO downlink transmission, MIMO interference channel, and MIMO
wiretap channel. Additionally, we discuss the transmission designs with
discrete input signals for other systems using MIMO technology. Finally,
technical challenges which remain unresolved at the time of writing are
summarized and the future trends of transmission designs with discrete input
signals are addressed.Comment: 110 pages, 512 references, submit to Proceedings of the IEE
Energy Efficient Precoding Design for SWIPT in MIMO Two-Way Relay Networks
In this paper, we study the energy efficiency (EE) maximization problem in
multiple-input multiple-output (MIMO) two-way relay networks with simultaneous
wireless information and power transfer (SWIPT). The network consists of a
multiple-antenna amplify-and-forward relay node which provides bidirectional
communications between two multiple-antenna transceiver nodesComment: 16 pages, 6 figures, to appear in IEEE Transactions on Vehicular
Technolog
Precoder Design for Multi-antenna Partial Decode-and-Forward (PDF) Cooperative Systems with Statistical CSIT and MMSE-SIC Receivers
Cooperative communication is an important technology in next generation
wireless networks. Aside from conventional amplify-and-forward (AF) and
decode-and-forward (DF) protocols, the partial decode-and-forward (PDF)
protocol is an alternative relaying scheme that is especially promising for
scenarios in which the relay node cannot reliably decode the complete source
message. However, there are several important issues to be addressed regarding
the application of PDF protocols. In this paper, we propose a PDF protocol and
MIMO precoder designs at the source and relay nodes. The precoder designs are
adapted based on statistical channel state information for correlated MIMO
channels, and matched to practical minimum mean-square-error successive
interference cancelation (MMSE-SIC) receivers at the relay and destination
nodes. We show that under similar system settings, the proposed MIMO precoder
design with PDF protocol and MMSE-SIC receivers achieves substantial
performance enhancement compared with conventional baselines
Massive MIMO and Millimeter Wave for 5G Wireless HetNet: Potentials and Challenges
There have been active research activities worldwide in developing the
next-generation 5G wireless network. The 5G network is expected to support
significantly large amount of mobile data traffic and huge number of wireless
connections, achieve better cost- and energy-efficiency as well as quality of
service (QoS) in terms of communication delay, reliability and security. To
this end, the 5G wireless network should exploit potential gains in different
network dimensions including super dense and heterogeneous deployment of cells
and massive antenna arrays (i.e., massive multiple input multiple output (MIMO)
technologies) and utilization of higher frequencies, in particular millimeter
wave (mmWave) frequencies. This article discusses potentials and challenges of
the 5G heterogeneous wireless network (HetNet) which incorporates massive MIMO
and mmWave technologies. We will first provide the typical requirements of the
5G wireless network. Then, the significance of massive MIMO and mmWave in
engineering the future 5G HetNet is discussed in detail. Potential challenges
associated with the design of such 5G HetNet are discussed. Finally, we provide
some case studies, which illustrate the potential benefits of the considered
technologies.Comment: IEEE Vehicular Technology Magazine (To appear
Full-Duplex MIMO-OFDM Communication with Self-Energy Recycling
This paper focuses on energy recycling in full-duplex (FD) relaying
multiple-input-multiple-output orthogonal frequency division multiplexing
(OFDM) communication. The loop self-interference (SI) due to full-duplexing is
seen as an opportunity for the energy-constrained relay node to replenish its
energy requirement through wireless power transfer. In forwarding the source
information to the destination, the FD relay can simultaneously harvest energy
from the source wireless transmission and also through energy recycling from
its own transmission. The objective is to maximize the overall spectral
efficiency by designing the optimal power allocation over OFDM sub-carriers and
transmit antennas. Due to a large number of sub-carriers, this design problem
poses a large-scale nonconvex optimization problem involving a few thousand
variables of power allocation, which is very computationally challenging. A new
path-following algorithm is proposed, which converges to an optimal solution.
This algorithm is very efficient since it is based on \textit{closed-form}
calculations. Numerical results for a practical simulation setting show
promising results by achieving high spectral efficiency
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