7,633 research outputs found
Two High-performance Schemes of Transmit Antenna Selection for Secure Spatial Modulation
In this paper, a secure spatial modulation (SM) system with artificial noise
(AN)-aided is investigated. To achieve higher secrecy rate (SR) in such a
system, two high-performance schemes of transmit antenna selection (TAS),
leakage-based and maximum secrecy rate (Max-SR), are proposed and a generalized
Euclidean distance-optimized antenna selection (EDAS) method is designed. From
simulation results and analysis, the four TAS schemes have an decreasing order:
Max-SR, leakage-based, generalized EDAS, and random (conventional), in terms of
SR performance. However, the proposed Max-SR method requires the exhaustive
search to achieve the optimal SR performance, thus its complexity is extremely
high as the number of antennas tends to medium and large scale. The proposed
leakage-based method approaches the Max-SR method with much lower complexity.
Thus, it achieves a good balance between complexity and SR performance. In
terms of bit error rate (BER), their performances are in an increasing order:
random, leakage-based, Max-SR, and generalized EDAS
Low-Complexity Linear Precoding for Secure Spatial Modulation
In this work, we investigate linear precoding for secure spatial modulation.
With secure spatial modulation, the achievable secrecy rate does not have an
easy-to-compute mathematical expression, and hence, has to be evaluated
numerically, which leads to high complexity in the optimal precoder design. To
address this issue, an accurate and analytical approximation of the secrecy
rate is derived in this work. Using this approximation as the objective
function, two low-complexity linear precoding methods based on gradient descend
(GD) and successive convex approximation (SCA) are proposed. The GD-based
method has much lower complexity but usually converges to a local optimum. On
the other hand, the SCA-based method uses semi-definite relaxation to deal with
the non-convexity in the precoder optimization problem and achieves
near-optimal solution. Compared with the existing GD-based precoder design in
the literature that directly uses the exact and numerically evaluated secrecy
capacity as the objective function, the two proposed designs have significantly
lower complexity. Our SCA-based design even achieves a higher secrecy rate than
the existing GD-based design.Comment: 11pages, 8figure
Two High-Performance Amplitude Beamforming Schemes for Secure Precise Communication and Jamming with Phase Alignment
To severely weaken the eavesdropper's ability to intercept confidential
message (CM), a precise jamming (PJ) idea is proposed by making use of the
concept of secure precise wireless transmission (SPWT). Its basic idea is to
focus the transmit energy of artificial noise (AN) onto the neighborhood of
eavesdropper (Eve) by using random subcarrier selection (RSS), directional
modulation, phase alignment (PA), and amplitude beamforming (AB). By doing so,
Eve will be seriously interfered with AN. Here, the conventional joint
optimization of phase and amplitude is converted into two independent phase and
amplitude optimization problems. Considering PJ and SPWT require PA, the joint
optimization problem reduces to an amplitude optimization problem. Then, two
efficient AB schemes are proposed: leakage and maximizing receive
power(Max-RP). With existing equal AB (EAB) as a performance reference,
simulation results show that the proposed Max-RP and leakage AB methods perform
much better than conventional method in terms of both bit-error-rate (BER) and
secrecy rate (SR) at medium and high signal-to-noise ratio regions. The
performance difference between the two proposed leakage and Max-RP amplitude
beamformers is trivial. Additionally, we also find the fact that all three AB
schemes EA, Max-RP, and leakage can form two main peaks of AN and CM around Eve
and the desired receiver (Bob), respectively. This is what we call PJ and SPWT
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
Reflecting Modulation
Reconfigurable intelligent surface (RIS) has emerged as a promising technique
for future wireless communication networks. How to reliably transmit
information in a RIS-based communication system arouses much interest. This
paper proposes a reflecting modulation (RM) scheme for RIS-based
communications, where both the reflecting patterns and transmit signals can
carry information. Depending on that the transmitter and RIS jointly or
independently deliver information, RM is further classified into two
categories: jointly mapped RM (JRM) and separately mapped RM (SRM). JRM and SRM
are naturally superior to existing schemes, because the transmit signal
vectors, reflecting patterns, and bit mapping methods of JRM and SRM are more
flexibly designed. To enhance transmission reliability, this paper proposes a
discrete optimization-based joint signal mapping, shaping, and reflecting
(DJMSR) design for JRM and SRM to minimize the bit error rate (BER) with a
given transmit signal candidate set and a given reflecting pattern candidate
set. To further improve the performance, this paper optimizes multiple
reflecting patterns and their associated transmit signal sets in continuous
fields for JRM and SRM. Numerical results show that JRM and SRM with the
proposed system optimization methods considerably outperform existing schemes
in BER.Comment: accepted for publication in IEEE JSAC SI titled Wireless Networks
Empowered by Reconfigurable Intelligent Surface
Symbol-level and Multicast Precoding for Multiuser Multiantenna Downlink: A Survey, Classification and Challenges
Precoding has been conventionally considered as an effective means of
mitigating the interference and efficiently exploiting the available in the
multiantenna downlink channel, where multiple users are simultaneously served
with independent information over the same channel resources. The early works
in this area were focused on transmitting an individual information stream to
each user by constructing weighted linear combinations of symbol blocks
(codewords). However, more recent works have moved beyond this traditional view
by: i) transmitting distinct data streams to groups of users and ii) applying
precoding on a symbol-per-symbol basis. In this context, the current survey
presents a unified view and classification of precoding techniques with respect
to two main axes: i) the switching rate of the precoding weights, leading to
the classes of block- and symbol-level precoding, ii) the number of users that
each stream is addressed to, hence unicast-/multicast-/broadcast- precoding.
Furthermore, the classified techniques are compared through representative
numerical results to demonstrate their relative performance and uncover
fundamental insights. Finally, a list of open theoretical problems and
practical challenges are presented to inspire further research in this area.Comment: Submitted to IEEE Communications Surveys & Tutorial
Machine-Learning-based High-resolution DOA Measurement and Robust DM for Hybrid Analog-Digital Massive MIMO Transceiver
At hybrid analog-digital (HAD) transceiver, an improved HAD rotational
invariance techniques (ESPRIT), called I-HAD-ESPRIT, is proposed to measure the
direction of arrival (DOA) of desired user, where the phase ambiguity due to
HAD structure is addressed successfully. Subsequently, a machine-learning (ML)
framework is proposed to improve the precision of measuring DOA. In the
training stage, the HAD transceiver works as a receiver and repeatedly measures
the values of DOA via I-HAD-ESPRIT to form a slightly large training data set
(TDS) of DOA. From TDS, we find that the probability density function (PDF) of
DOA measurement error (DOAME) is approximated as a Gaussian distribution by the
histogram method in ML. This TDS is used to learn the mean of DOA and the
variance of DOAME, which are utilized to infer their values and improve their
precisions in the real-time stage. The HAD transceiver rapidly measures the
real-time value of DOA some times to form a relatively small real-time set
(RTS), which is used to learn the real-time mean and variance of DOA/ DOAME.
Then, three weight combiners are proposed to combine
the-maximum-likelihood-learning outputs of TDS and RTS. Their weight factors
depend intimately on the numbers of elements in TDS and RTS, and
signal-to-noise ratios during the two stages. Using the mean and variance of
DOA/DOAME, their PDFs can be given directly, and we propose a robust beamformer
for directional modulation (DM) transmitter with HAD by fully exploiting the
PDF of DOA/DOAME, especially a robust analog beamformer on RF chain. Simulation
results show that: 1) The proposed I-HAD-ESPRIT can achieve the HAD CRLB; 2)
The proposed ML framework performs much better than the corresponding real-time
one without training stage, 3) The proposed robust DM transmitter can perform
better than the corresponding non-robust ones in terms of bit error rate and
secrecy rate.Comment: 14 pages, 11 figure
A Novel Compressive Sensing based Enhanced Multiplexing Scheme for MIMO System
A novel compressive-sensing based signal multiplexing scheme is proposed in
this paper to further improve the multiplexing gain for multiple input multiple
output (MIMO) system. At the transmitter side, a Gaussian random measurement
matrix in compressive sensing is employed before the traditional spatial
multiplexing in order to carry more data streams on the available spatial
multiplexing streams of the underlying MIMO system. At the receiver side, it is
proposed to reformulate the detection of the multiplexing signal into two
steps. In the first step, the traditional MIMO equalization can be used to
restore the transmitted spatial multiplexing signal of the MIMO system. While
in the second step, the standard optimization based detection algorithm assumed
in the compressive sensing framework is utilized to restore the CS multiplexing
data streams, wherein the exhaustive over-complete dictionary is used to
guarantee the sparse representation of the CS multiplexing signal. In order to
avoid the excessive complexity, the sub-block based dictionary and the
sub-block based CS restoration is proposed. Finally, simulation results are
presented to show the feasibility of the proposed CS based enhanced MIMO
multiplexing scheme. And our efforts in this paper shed some lights on the
great potential in further improving the spatial multiplexing gain for the MIMO
system.Comment: 5 pages, 5 figure
Fundamental Green Tradeoffs: Progresses, Challenges, and Impacts on 5G Networks
With years of tremendous traffic and energy consumption growth, green radio
has been valued not only for theoretical research interests but also for the
operational expenditure reduction and the sustainable development of wireless
communications. Fundamental green tradeoffs, served as an important framework
for analysis, include four basic relationships: spectrum efficiency (SE) versus
energy efficiency (EE), deployment efficiency (DE) versus energy efficiency
(EE), delay (DL) versus power (PW), and bandwidth (BW) versus power (PW). In
this paper, we first provide a comprehensive overview on the extensive on-going
research efforts and categorize them based on the fundamental green tradeoffs.
We will then focus on research progresses of 4G and 5G communications, such as
orthogonal frequency division multiplexing (OFDM) and non-orthogonal
aggregation (NOA), multiple input multiple output (MIMO), and heterogeneous
networks (HetNets). We will also discuss potential challenges and impacts of
fundamental green tradeoffs, to shed some light on the energy efficient
research and design for future wireless networks.Comment: revised from IEEE Communications Surveys & Tutorial
Efficient Receive Beamformers for Secure Spatial Modulation against a Malicious Full-duplex Attacker with Eavesdropping Ability
In this paper, we consider a new secure spatial modulation scenario with a
full-duplex (FD) malicious attacker Mallory owning eavesdropping capacity,
where Mallory works on FD model and transmits a malicious jamming such as
artificial noise (AN) to interfere with Bob. To suppress the malicious jamming
on Bob from Mallory, a conventional maximum receive power (Max-RP) at Bob is
presented firstly. Subsequently, to exploit the colored property of noise plus
interference at Bob, a whitening-filter-based Max-RP (Max-WFRP) is proposed
with an obvious performance enhancement over Max-RP. To completely remove the
malicious jamming from Mallory, a Max-RP with a constraint of forcing the
malicious jamming from Mallory to zero at Bob is proposed. To further improve
secrecy rate (SR) by removing the ZF contraint (ZFC), the maximum
signal-to-jamming-plus-noise ratio (Max-SJNR) is proposed. Our proposed methods
have closed-form expressions. From simulation results, the four receive
beamforming methods have an increasing order in performance: Max-RP, Max-RP
with ZFC and Max-SJNRMax-WFRP. Additionally, the latter two harvest a
substantial performance gains over Max-RP and Max-RP with ZFC in the low and
medium signal-to-noise ratio regions
- …