[Show abstract][Hide abstract] ABSTRACT: This paper investigates the system achievable rate and optimization for the
multiple-input multiple-output (MIMO)-orthogonal frequency division
multiplexing (OFDM) system with an energy harvesting (EH) relay. Firstly we
propose a time switchingbased relaying (TSR) protocol to enable the
simultaneous information processing and energy harvesting at the relay. Then,
we discuss its achievable rate performance theoretically and formulated an
optimization problem to maximize the system achievable rate. As the problem is
difficult to solve, we design an Augmented Lagrangian Penalty Function (ALPF)
method for it. Extensive simulation results are provided to demonstrate the
accuracy of the analytical results and the effectiveness of the ALPF method.
[Show abstract][Hide abstract] ABSTRACT: Recently, energy harvesting (EH) has emerged as a promising way to realize
green communications. In this paper, we investigate the multiuser transmission
network with an EH cooperative relay, where a source transmits independent
information to multiple destinations with the help of an energy constrained
relay. The relay can harvest energy from the radio frequency (RF) signals
transmitted from the source, and it helps the multiuser transmission only by
consuming the harvested energy. By adopting the time switching and the
power-splitting relay receiver architectures, we firstly propose two protocols,
the time-switching cooperative multiuser transmission (TSCMT) protocol and the
power-splitting cooperative multiuser transmission (PSCMT) protocol, to enable
the simultaneous information processing and EH at the relay for the system. To
evaluate the system performance, we theoretically analyze the system outage
probability for the two proposed protocols, and then derive explicit
expressions for each of them, respectively. Moreover, we also discuss the
effects of system configuration parameters, such as the source power and relay
location on the system performance. Numerical results are provided to
demonstrate the accuracy of our analytical results and reveal that compared
with traditional non-cooperative scheme, our proposed protocols are green
solutions to offer reliable communication and lower system outage probability
without consuming additional energy. In particular, for the same transmit power
at the source, the PSCMT protocol is superior to the TSCMT protocol to obtain
lower system outage probability.
[Show abstract][Hide abstract] ABSTRACT: Energy harvesting (EH) and network coding (NC) have emerged as two promising
technologies for future wireless networks. In this paper, we combine them
together in a single system and then present a time switching-based network
coding relaying (TSNCR) protocol for the two-way relay system, where an energy
constrained relay harvests energy from the transmitted radio frequency (RF)
signals from two sources, and then helps the two-way relay information exchange
between the two sources with the consumption of the harvested energy. To
evaluate the system performance, we derive an explicit expression of the outage
probability for the proposed TSNCR protocol. In order to explore the system
performance limit, we formulate an optimization problem to minimize the system
outage probability. Since the problem is non-convex and cannot be directly
solved, we design a genetic algorithm (GA)-based optimization algorithm for it.
Numerical results validate our theoretical analysis and show that in such an EH
two-way relay system, if NC is applied, the system outage probability can be
greatly decreased. Moreover, it is shown that the relay position greatly
affects the system performance of TSNCR, where relatively worse outage
performance is achieved when the relay is placed in the middle of the two
sources. This is the first time to observe such a phenomena in EH two-way relay
[Show abstract][Hide abstract] ABSTRACT: This paper investigates the simultaneous wireless information and power
transfer (SWIPT) for two-hop orthogonal frequency division multiplexing (OFDM)
decode-and-forward (DF) relay communication system, where a relay harvests
energy from radio frequency signals transmitted by the source and then uses the
harvested energy to assist the information transmission from the source to its
destination. The power splitting receiver is considered at the relay, which
splits the received signal into two power streams to perform information
decoding (ID) and energy harvesting (EH) respectively. For better understanding
the behavior and exploring the performance limit of such a system, resource
allocation is studied to maximize the total achievable transmission rate. An
optimization problem, which jointly takes into account the power allocation,
the subcarrier pairing and the power splitting, is formulated. Due to its
non-convexity, a resource allocation policy with low complexity based on
separation principle is designed. Simulation results show that the system
performance can be significantly improved by using our proposed policy.
Moreover, the system performance behavior to the relay position is also
discussed, and results show that in the two-hop OFDM system with EH relay, the
relay should be deployed near the source, while in that with conventional
non-EH relay, it should be deployed at the middle between the source and the
[Show abstract][Hide abstract] ABSTRACT: Biometric template protection is indispensable to protect personal privacy in large-scale deployment of biometric systems. Accuracy, changeability, and security are three critical requirements for template protection algorithms. However, existing template protection algorithms cannot satisfy all these requirements well. In this paper, we propose a hybrid approach that combines random projection and fuzzy vault to improve the performances at these three points. Heterogeneous space is designed for combining random projection and fuzzy vault properly in the hybrid scheme. New chaff point generation method is also proposed to enhance the security of the heterogeneous vault. Theoretical analyses of proposed hybrid approach in terms of accuracy, changeability, and security are given in this paper. Palmprint database based experimental results well support the theoretical analyses and demonstrate the effectiveness of proposed hybrid approach.
[Show abstract][Hide abstract] ABSTRACT: Fuzzy vault scheme (FVS) is one of the most popular biometric cryptosystems for biometric template protection. However, error correcting code (ECC) proposed in FVS is not appropriate to deal with real-valued biometric intraclass variances. In this paper, we propose a multidimensional fuzzy vault scheme (MDFVS) in which a general subspace error-tolerant mechanism is designed and embedded into FVS to handle intraclass variances. Palmprint is one of the most important biometrics; to protect palmprint templates; a palmprint based MDFVS implementation is also presented. Experimental results show that the proposed scheme not only can deal with intraclass variances effectively but also could maintain the accuracy and meanwhile enhance security.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a cooperative transmission scheme for cooperative multi-relay high-speed railway mobile communication system, where fountain codes and mutual information accumulation (IA) method are adopted. The spreading codes are used to separate and detect the signal with interference from multiple relays, and the signal detection process and information receiving strategy at the destination are designed. Then we analyze the performance of the system in terms of the transmission rate, where the probability density function of the transmission rate of IA is derived, as well as the corresponding average transmission rate. For comparison, the traditional energy accumulation (EA) based receiving scheme is also analyzed. Results show when spreading codes are not orthogonal, if the signal to noise ratio (SNR) is relatively low, the performance of IA-based information receiving method is worse than that of EA-based one, and if SNR is relatively high, the performance of IA-based information receiving method is superior to that of EA-based one.
2013 International Workshop on High Mobility Wireless Communications (HMWC); 11/2013
[Show abstract][Hide abstract] ABSTRACT: To enhance the symbol error rate (SER) performance of the two-way relay channels with physical layer network coding, this letter proposes a relay selection scheme, in which the relay with the maximal minimum distance between different points in its constellation among all relays is selected to assist two-way transmissions. We give the closed-form expression of minimum distance for binary phase-shift keying and quadrature phase-shift keying. Additionally, we design a low-complexity method for higher-order modulations based on look-up tables. Simulation results show that the proposed scheme improves the SER performance for two-way relay networks.
[Show abstract][Hide abstract] ABSTRACT: Weighted sum-rate maximization with transmit power limit and energy harvesting constraints is considered in the context of two-way collaborative relay systems. We discuss an ideal scheme where the source nodes can decode information signal and harvest energy, simultaneously. An iterative algorithm based on semidefinite relaxation (SDR) and successive convex approximation (SCA) is developed to obtain (at least) a local optimal solution. In view of the limitation of the current circuits, we propose a practical ping-pong scheme wherein the source node can only perform one operation at a time. Furthermore, the iterative algorithm and its convergence are extended to such a case. The efficacy of the proposed algorithms is validated by numerical experiments.
Communications (ICC), 2013 IEEE International Conference on; 01/2013
[Show abstract][Hide abstract] ABSTRACT: This paper studies the beamforming design of two-way relay systems for simultaneous information and power transfer with consideration of imperfect channel state information (CSI). To this end, we seek the robust beamforming design to maximize the weighted sum rate under the power constraint at relay nodes and the energy harvesting constraints at the two source nodes. Due to the infinitely many nonconvex constraints, the robust beamforming design problem is challenging. Therefore, we firstly propose an approximate to the signal to interference plus noise ratio (SINR). Then an iterative algorithm is developed based on the semidefinite relaxation (SDR), S-procedure and successive convex approximation (SCA) techniques. Furthermore, the effectiveness of the proposed algorithm is validated by numerical experiments.
Acoustics, Speech and Signal Processing (ICASSP), 2013 IEEE International Conference on; 01/2013
[Show abstract][Hide abstract] ABSTRACT: Multicell coordinated beamforming (MCBF), where multiple base stations (BSs) collaborate with each other in the beamforming design for mitigating the intercell interference (ICI), has been a subject drawing great attention recently. Most MCBF designs assume perfect channel state information (CSI) of mobile stations (MSs); however CSI errors are inevitable at the BSs in practice. Assuming elliptically bounded CSI errors, this paper studies the robust MCBF design problem that minimizes the weighted sum power of BSs subject to worst-case signal-to-interference-plus-noise ratio (SINR) constraints on the MSs. Our goal is to devise a distributed optimization method to obtain the worst-case robust beamforming solutions in a decentralized fashion with only local CSI used at each BS and limited backhaul information exchange between BSs. However, the considered problem is difficult to handle even in the centralized form. We first propose an efficient approximation method for solving the nonconvex centralized problem, using semidefinite relaxation (SDR), an approximation technique based on convex optimization. Then a distributed robust MCBF algorithm is further proposed, using a distributed convex optimization technique known as alternating direction method of multipliers (ADMM). We analytically show the convergence of the proposed distributed robust MCBF algorithm to the optimal centralized solution. We also extend the worst-case robust beamforming design as well as its decentralized implementation method to a fully coordinated scenario. Simulation results are presented to examine the effectiveness of the proposed SDR method and the distributed robust MCBF algorithm.
IEEE Transactions on Signal Processing 06/2012; 60(6):2988-3003. · 3.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper considers robust multi-cell coordinated beamforming (MCBF) design for downlink wireless systems, in the presence of channel state information (CSI) errors. By assuming that the CSI errors are complex Gaussian distributed, we formulate a chance-constrained robust MCBF design problem which guarantees that the mobile stations can achieve the desired signal-to-interference-plus-noise ratio (SINR) requirements with a high probability. A convex approximation method, based on semidefinite relaxation and tractable probability approximation formulations, is proposed. The goal is to solve the convex approximation formulation in a distributed manner, with only a small amount of information exchange between base stations. To this end, we develop a distributed implementation by applying a convex optimization method, called weighted variable-penalty alternating direction method of multipliers (WVP-ADMM), which is numerically more stable and can converge faster than the standard ADMM method. Simulation results are presented to examine the chance-constrained robust MCBF design and the proposed distributed implementation algorithm.
Global Communications Conference (GLOBECOM), 2012 IEEE; 01/2012
[Show abstract][Hide abstract] ABSTRACT: Currently, single sample biometrics recognition (SSBR) has emerged as one of the major research contents. It may lead to bad
recognition result. To solve this problem, we present a novel approach by fusing two kinds of hand-based biometrics, i.e.,
palmprint and middle finger. We obtain their discriminant features by combining statistical information and structural information
of each modal which are extracted using locality preserving projection (LPP) based on wavelet transform (WT). In order to
reduce the influence of affine transform, we utilize mean filtering to enhance the robustness of structural information to
improve the discriminant ability of palmprint high-frequency sub-bands. The two types of features are then fused at score
level for the final hand-based SSBR. The experiments on the hand image database that contains 1,000 samples from 100 individuals
show that the proposed feature extraction and fusion methods lead to promising performance.
KeywordsSingle sample biometrics recognition–Palmprint and middle finger biometrics–Wavelet transform–Structural feature enhancement–Feature fusion
Neural Computing and Applications 11/2011; · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Signal-Time Coding (STC), a novel transmission mechanism, was proposed recently. It combines the traditional encoding/modulation mode in the signal domain with the signal pulse phase modulation in the time domain and can achieve higher information flow rate in some cases for relay networks. However, there are still many fundamental problems to be investigated. This paper considers the implementing issue of STC in AWGN relay networks. Firstly, an energy detection based STC (ED-STC) scheme is proposed and the error probabilities of ED-STC in both the signal domain and the time domain are given. Secondly, a performance evaluation criterion, the reliable information per symbol (RIPS), is proposed to characterize the performance of STC in noisy wireless networks. Moreover, the performance bounds of the RIPS of ED-STC are derived. Numerical analysis show that ED-STC outperforms traditional transmission method in terms of effective information rate within some practical conditions.
Communications (ICC), 2011 IEEE International Conference on; 07/2011
[Show abstract][Hide abstract] ABSTRACT: Multi-cell coordinated beamforming (MCBF), where multiple base stations (BSs)
collaborate with each other in the beamforming design for mitigating the
inter-cell interference, has been a subject drawing great attention recently.
Most MCBF designs assume perfect channel state information (CSI) of mobile
stations (MSs); however CSI errors are inevitable at the BSs in practice.
Assuming elliptically bounded CSI errors, this paper studies the robust MCBF
design problem that minimizes the weighted sum power of BSs subject to
worst-case signal-to-interference-plus-noise ratio (SINR) constraints on the
MSs. Our goal is to devise a distributed optimization method that can obtain
the worst-case robust beamforming solutions in a decentralized fashion, with
only local CSI used at each BS and little backhaul signaling for message
exchange between BSs. However, the considered problem is difficult to handle
even in the centralized form. We first propose an efficient approximation
method in the centralized form, based on the semidefinite relaxation (SDR)
technique. To obtain the robust beamforming solution in a decentralized
fashion, we further propose a distributed robust MCBF algorithm, using a
distributed convex optimization technique known as alternating direction method
of multipliers (ADMM). We analytically show the convergence of the proposed
distributed robust MCBF algorithm to the optimal centralized solution and its
better bandwidth efficiency in backhaul signaling over the existing dual
decomposition based algorithms. Simulation results are presented to examine the
effectiveness of the proposed SDR method and the distributed robust MCBF
[Show abstract][Hide abstract] ABSTRACT: Multicell coordinated beamforming (MCBF) has been recognized as a promising
approach to enhancing the system throughput and spectrum efficiency of wireless
cellular systems. In contrast to the conventional single-cell beamforming (SBF)
design, MCBF jointly optimizes the beamforming vectors of cooperative base
stations (BSs) (via a central processing unit(CPU)) in order to mitigate the
intercell interference. While most of the existing designs assume that the CPU
has the perfect knowledge of the channel state information (CSI) of mobile
stations (MSs), this paper takes into account the inevitable CSI errors at the
CPU, and study the robust MCBF design problem. Specifically, we consider the
worst-case robust design formulation that minimizes the weighted sum
transmission power of BSs subject to worst-case
signal-to-interference-plus-noise ratio (SINR) constraints on MSs. The
associated optimization problem is challenging because it involves infinitely
many nonconvex SINR constraints. In this paper, we show that the worst-case
SINR constraints can be reformulated as linear matrix inequalities, and the
approximation method known as semidefinite relation can be used to efficiently
handle the worst-case robust MCBF problem. Simulation results show that the
proposed robustMCBF design can provide guaranteed SINR performance for the MSs
and outperforms the robust SBF design.
[Show abstract][Hide abstract] ABSTRACT: Nowadays, more and more applications are expected to be employed on energy-limited mobile terminals (MTs), with the rapid growth of embedded platforms' computational abilities and mobile subscribes' requirements. Thus, how to save the power consumption for the MT is becoming more and more important. To this end, deploying relay stations (RSs) in cellular networks has been considered as one of the most effective techniques. In this work, we investigate how to optimize MT's transmission power in cellular networks, where two-way transmission are considered and RSs' locations, MT's path selections and bandwidth resources allocation are jointly optimized using genetic algorithm (GA). Numerical results show that MT's transmission power is significantly reduced through the optimization of our method. Furthermore, we also investigate the influences of RS's coverage on MT's transmission power, and the numerical results show that the best RS's covering radius should be 50%∼70% of the cell radius.
Wireless, Mobile & Multimedia Networks (ICWMMN 2011), 4th IET International Conference on; 01/2011
[Show abstract][Hide abstract] ABSTRACT: Fuzzy vault scheme is one of the most popular biometric cryptosystems. However, the scheme is designed for set differences while Euclidean distance is often used in biometric techniques. Multidimensional fuzzy vault scheme (MDFVS) is a modified version that can be easily implemented based on biometric feature data. In MDFVS, every point is a vector, and Euclidean distance measure is used for genuine points filtering. To get better performances, the step of feature selection in the MDFVS algorithms is very important and should be well designed. In this paper we propose applying recognition rate to measure discrimination of features and selecting strong distinctive features into genuine points. Some principles of selecting strong distinctive features to compose genuine points are discussed. An implementation of MDFVS with feature selection is also presented. Experimental results based on palmprint show that the proposed feature selection approach improves the performances of MDFVS.
Biometric Recognition - 6th Chinese Conference, CCBR 2011, Beijing, China, December 3-4, 2011. Proceedings; 01/2011
[Show abstract][Hide abstract] ABSTRACT: Wireless Network coding requires cooperation among nodes, whereas selfish behaviors of nodes result huge decline in network performance. How to stimulate nodes to cooperate is a hot topic in wireless network coding theory. The paper addresses issue of cooperation in unicast network coding via a game theoretic approach. Considering the realization of network coding over fading channels, a load-balanced cooperation stimulation mechanism based on repeated game theoretic model is proposed. Theoretic analysis and simulation results show that our scheme can stimulate nodes to cooperate and achieve good load balance of network which brought by selfish behaviors of nodes.
Wireless, Mobile & Multimedia Networks (ICWMMN 2011), 4th IET International Conference on; 01/2011