Journal of Applied Sciences

Multi-objective Optimization of Cross-Layer Resource Allocation in Cooperative Relay Systems

TANG Lun1;2, LONG Ye-hua1, CHEN Qian-bin1, ZENG Xiao-ping2

2011, 29(4): 331-339. doi:10.3969/j.issn.0255-8297.2011.04.001

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Joining optimization in reliability, transmission rate and power consumption in the cooperative relay networks is addressed in the paper. Formulas of reliability, transmission rate and power consumption are analyzed, and two optimization models proposed: maximization of network utility model depending on reliability and transmission rate, and minimization of power consumption. To implement compromise among
reliability, transmission rate and power consumption, a cross-layer optimization model is proposed to combine
network utility and power consumption. With the Lagrangian decomposition method, a distributed algorithm
is developed to solve the joining optimization problem. The algorithm can achieve tradeoff between reliability
and transmission rate by changing a factor ?. Further adjustment of the tradeoff factor in the joining optimization
model leads to a tradeoff between network utility and power consumption. Simulation results show
that the proposed algorithm is effective to achieve a tradeoff among reliability, transmission rate and power
consumption.

Opportunistic Scheduling with Relay Selection in Wireless Multi-channel Relay Network

ZHAO Chuan-xin1;3, WANG Ru-chuan2;3, HUANG Hai-ping2, SUN Li-juan2

2011, 29(4): 340-346. doi:10.3969/j.issn.0255-8297.2011.04.002

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Abstract: In this paper we study scheduling for selecting multiple relay nodes in orthogonal frequency division
multiple access (OFDMA) relay network to enhance the system throughput. We propose an opportunistic
scheduling model with relay nodes selection. The aim is to compromise between system throughput and
user fairness with the constraint of channel assignment without interference. We propose two opportunistic
scheduling algorithms in view of route diversity and link diversity, which combine relay selection and channel
assignment to establish user route and optimally select user. Simulations show that the two algorithms can
improve network throughput significantly and ensure user fairness.

Compressed Sensing Based Sparse Channel Estimation in MIMO Systems

WANG Ni-na1, GUI Guan2;3, ZHANG Zhi1, TANG Tian1

2011, 29(4): 347-352. doi:10.3969/j.issn.0255-8297.2011.04.003

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Abstract: In MIMO systems, channel state information (CSI) is necessary for coherent detection and channel
equalization at the receiver. Traditional channel estimation methods such as least squares (LS) and minimum
mean square error (MMSE) are based on the rich multipath assumption which leads to low frequency spectrum
utilization. This paper studies sparse channel estimation for single carrier MIMO systems. A novel method
based on compressed sensing is proposed by using sparsity, which can obtain accurate CSI with fewer pilots so
as to improve frequency spectrum utilization. Simulation and theoretical analysis show that the compressive
sampling matching pursuit (CoSaMP) estimation is the best choice for MIMO sparse multipath channel estimation.

On-Demand Multiple Channels Access Strategy in Cognitive Radio Networks Based on Pricing

WANG Fan1;2, ZHAO Hang-sheng2, YAO Fu-qiang2, FENG Shao-dong1, ZHANG Jian-zhao1;

2011, 29(4): 353-359. doi:10.3969/j.issn.0255-8297.2011.04.004

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Abstract: In the scenario of multi-channel access cognitive radio networks, considering the QoS guarantee, a
model is established based on non-cooperative game theory, and a new metric called useful CRN throughput is
defined. Based on the proposed model, an on-demand pricing based multi-channel access strategy is proposed.
A closed-form formulation of the price function is formulated. In addition, an on-demand pricing based iterative
water filling algorithm (ODPA) is introduced to implement channel and power allocation in the multi-channel
access strategy. Simulation results show that the proposed ODPA can achieve better performance in both
metrics of useful CRN throughput and QoS guarantee rate. Simulation shows that the QoS guarantee rate
is improved by 10%?20% with ODPA as compared to other pricing based water-filling algorithm without
considering the QoS requirement. The CRN throughput is improved by about 38%.

Performance of Code Domain Transmitted Reference IR-UWB System

LI Xia, JIANG Hua, ZHANG Jian, ZHANG Zhi-yuan

2011, 29(4): 360-367. doi:10.3969/j.issn.0255-8297.2011.04.005

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Based on the time domain and frequency domain transmitted reference IR-UWB systems, this
paper studies optimization design of code domain transmitted reference IR UWB system, and derives bit error
rate (BER) of the system based on pulse peak energy. The system performance under the condition of additive
Gauss white noise (AWGN) and multipath fading channel is simulated and compared with the time domain and
frequency domain transmitted reference structures. Theoretical analysis and simulation results show that the
performance of the code domain transmitted reference IR UWB system is superior to the time and frequency
domain systems.

Signal Transmitted from Switched Antenna Array with Low Interception Probability for Physical Layer Security

HONG Tao, SONG Mao-zhong, LIU Yu

2011, 29(4): 368-373. doi:10.3969/j.issn.0255-8297.2011.04.006

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Abstract: A signal transmitted from a switched antenna array with low probability of interception is proposed
to ensure information security in the physical layer transmission. The main idea is that the transmitter
estimates channel information from a training sequence transmitted by the mobile terminal and randomly
selects several antennas for fast switching transmission. Weighting coefficients of each antenna are calculated
according to channel information and the spread-spectrum sequence. Therefore, the signal is a space-spreadspectrum
signal associated with the spread-spectrum sequence and the channel information of each antenna.
In this way, the desired receiver with a single antenna can demodulate the received signal as traditional spreadspectrum
signals, while eavesdroppers cannot extract any useful information from the received signal even if
eavesdroppers know the spread-spectrum sequence of the transmit signal because of the fast switching of the
transmit antenna. Simulation results show that the signal has the same ability of anti-eavesdropping, and has
anti-jamming capability with low probability of detection compared to a reference method.

Context Transfer Mechanism of Header Compression During Predictive Handover

ZHANG Zai-long, XU Xiao-fei, SUN Yan-fei

2011, 29(4): 374-380. doi:10.3969/j.issn.0255-8297.2011.04.007

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We study context transfer mechanism to reduce large overhead in re-establishing context of header
compression, and propose a two-step method for context transfer of header compression and a real-time trigger
strategy for context transfer using link-layer trigger. The proposed approach avoids the expensive process of
context re-establishment of header compression by transferring header compression context when handovers
are required. The handover delay, packet loss and state migration of header compression with and without
context transfer of header compression are evaluated with NS2. Simulation results show that the method can
establish and synchronize context at the compressor and decompressor so as to reduce the handover impact on
header compression.

Adaptive Resource Allocation Based on QoS in OFDM Cognitive Radio System

XU Shuang, ZHAO Xiao-hui, YUAN Hao

2011, 29(4): 381-384. doi:10.3969/j.issn.0255-8297.2011.04.008

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Abstract: Based on the characteristics of cognitive radio and transmission properties of OFDM, an adaptive resource allocation algorithm in OFDM cognitive radio system is proposed. By keeping the interference introduced to the primary users within a tolerable range in sub-carrier allocation and power allocation, the proposed algorithm maximizes the system throughout. In addition, this scheme can guarantee quality of service(QoS)
among secondary users based on a fairness principle. Simulation results show performance and effectiveness of this algorithm.

Puncturing Algorithm for Design Rate-Compatible LDPC Code

XIAO Min, LI Yong, WANG Lin

2011, 29(4): 385-389. doi:10.3969/j.issn.0255-8297.2011.04.009

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Rate compatibility of forward error correction codes is required to accomplish high throughput and reliability over time-varying wireless channels. The grouping and sorting (GS) algorithm can produce rate-compatible puncturing LDPC (RCP-LDPC) codes with good performance. However, there is a limit in the achievable highest puncturing rate. In this paper, a novel layer-by-layer sorting algorithm is proposed to design RCP-LDPC without any limitation in the highest puncturing rate. The algorithm can be applied to an arbitrary LDPC code to obtain a code rate infinitely close to one. Simulation over AWGN channels shows that the proposed algorithm has superior performance as compared to the GS algorithm.

Multi-granularity Synthesis Segmentation of Remote Sensing Image Based on Quotient Space Theory

LI Gang1, WAN You-chuan1, GUAN Yu-juan2

2011, 29(4): 390-396. doi:10.3969/j.issn.0255-8297.2011.04.010

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Abstract: Traditional segmentation method can only partition an image in a single granularity space, with segmentation accuracy limited to the single granularity space. This paper proposes a multi-granularity synthesis segmentation method for remote sensing images based on the quotient space granular theory. A quotient space model of multi-granularity image segmentation is discussed. Image data field is used to express the spatial
correlation of pixels, and fractal dimension used to enhance the capability of discrimination between artificial surface features and the natural scenes. The watershed algorithm and iterative self-organizing data analysis technique (ISODATA) are applied to the gray image, data field image and fractal dimension image to produce multi-granularity segmentation results. This paper proposes a specific quotient space synthesis algorithm for
multi-granularity image segmentation. Experiments show that the proposed method can take full advantage of the segmentation result in every granular space. The multi-granularity synthesis segmentation is effective and can produce more accurate segmentation than that of a single granularity space.

Selection of Time-Frequency Distribution for Extraction of Micro-Doppler Signatures

CHENG Xu, LIU Jin, WANG Xue-song, DAI Huan-yao

2011, 29(4): 397-404. doi:10.3969/j.issn.0255-8297.2011.04.011

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Aim at selection of time-frequency distribution (TFD) in the analysis of radar micro-Doppler
signature, we carry out theoretical analysis of the characteristics of micro-Doppler signal’s TFD. For multicomponent
micro-Doppler signal, specifications of TFD are given by criteria of objective assessment of the
TFD performance. Furthermore, a procedure of selecting optimal TFD for a given multi-component micro-
Doppler signal is provided. Simulation shows that the smoothed pseudo Wigner-Ville distribution has optimal
performance among the tested TFDs. The result provides guidance for TFD selection in the extraction of
micro-Doppler signatures and estimation of high-precision instantaneous frequency.

Joint Calculation of Decoding Path for Random Access in Multi-view Video Coding

CHENG Ming-ming1, AN Ping1;2, WANG Ping1, ZHANG Zhao-yang1;2

2011, 29(4): 405-409. doi:10.3969/j.issn.0255-8297.2011.04.012

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Abstract: Random-access performance is an important requirement for the evaluation of MVC prediction
structure. When random access happens, the system must be able to correctly calculate the decoding path. To
calculate the decoding path, previous studies were mainly concentrated in decoder. In this paper we propose a
new method for decode path calculation based on a reference frame list. The list is updated according to the
actual encoding information. Experimental results show that this method can accurately calculate the needed
frame. Moreover, the method can minimize the number of reference frame and improve the random access
performance.

Overlapped Domain Decomposition Method with Congruent Sub-domains for Electromagnetic Surface Integral Equations

HU Jun, HONG Wei, ZHOU Hou-xing, LI Wei-dong, SONG Zhe, XIE Jia-ye

2011, 29(4): 410-416. doi:10.3969/j.issn.0255-8297.2011.04.013

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An overlapped domain decomposition method with congruent sub-domains is proposed for solving
electromagnetic surface integral equations. Based on congruent sub-domains, the proposed method creates a
set of uniform mesh such that all the self-matrixes on the congruent sub-domains share an interior-interior
sub-matrix. The method can significantly reduce the memory requirement and the matrix filling time. It
can produce results consistent with those obtained with the MoM and the overlapped domain decomposition
method, while reduce the memory requirement and the CPU time. That is shown in the computation examples
presented in the paper, indicating correctness and effectiveness of the proposed method.

Preconditioned Restarted Changing Minimal Residual Method for Solving 3D EM Problems in a Half Space

LI Qing-bo, CAO Feng-lian, ZHOU Ping

2011, 29(4): 417-422. doi:10.3969/j.issn.0255-8297.2011.04.014

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Abstract: In order to efficiently solve large-scale asymmetric dense linear matrix in discrete field integral
equations, a preconditioned restarted changing minimal residual method based on the Hessenberg process
(CMRH) is proposed. It is used to implement the modified multilevel fast multi-pole algorithm (MLFMA)
to compute the scattering problem of perfect electric conductors in a lossy half space. MLFMA is used
to accelerate matrix vector multiplication of the CMRH. Scattering characteristics of the cylinder, the box
and the missile model are presented. Numerical results show that the CMRH method can efficiently reduce
both iteration number and convergence time as compared to the generalized minimal residual (GMRES).
Furthermore, CMRH is more easily combined with sparse approximate inverse (SAI) and symmetric successive
over relaxation (SSOR) preconditioning techniques, making it more practical.

Design of UHF Truncated Monopole Antenna and Its Matching Network

ZHANG Jun-rui, XIAO Shao-qiu, DING Xiao, TANG Ming-chun, BAI Yan-ying

2011, 29(4): 423-427. doi:10.3969/j.issn.0255-8297.2011.04.015

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A broadband monopole antenna working in UHF band is designed. A monopole antenna is cut
into two parts. They are connected in series. This step improves the horizontal gain in the upper part of the
operating band. A lossless LC ladder is then used to match the antenna impedance from 100 MHz to 400 MHz.
The truncating position and circuit element parameters in the matching network are obtained using CST2009
optimization. Reflection coefficients of the truncated antennas both with and without the matching network
are measured, showing good agreement with the simulation results. The following conclusions are drawn. The
gain in the horizontal direction of the antenna with matching network is more than 0 dBi between 100 MHz
and 350 MHz, and stays within ?7 ?0 dBi from 350 MHz to 400 MHz. The simulated reflection coefficient S11
of the antenna is below 10 dB within 100 MHz and 400 MHz. The efficiency is over 60% within the operating
band.

Sliding-Mode Trajectory Tacking Control for Underactuated Autonomous Surface Vehicle

LIAO Yu-lei, ZHUANG Jia-yuan, LI Ye, PANG Yong-jie

2011, 29(4): 428-434. doi:10.3969/j.issn.0255-8297.2011.04.016

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This paper addresses the trajectory planning and tacking control problem for underactuated autonomous
surface vehicles (ASV) with parametric modeling uncertainty and environmental disturbances. Given
a desired 2D smooth and inertial trajectory, the planning method uses vehicle dynamics to compute the bodyfixed
reference velocity and acceleration. A trajectory tacking control law is proposed based on the sliding-mode
control approach. Theoretical analysis shows that the ASV trajectory tacking system is asymptotically stable
and the yawing motion is BIBO stable under the control law. Simulation results are presented to show that
the ASV successfully follows a desired closed-loop or open-loop trajectory and achieves positioning control.
Feasibility and effectiveness of the presented controller is validated.

Multi-objective Optimization of Environmental Control System and Engine of Aircraft

LI Hong-bo1, DONG Xin-min1, LI Ting-ting2, GUO Jun1

2011, 29(4): 435-440. doi:10.3969/j.issn.0255-8297.2011.04.017

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An improved multi-objective particle swarm optimization algorithm is proposed and applied to the integrated optimization of environmental control system and engine of aircraft. A multi-objective optimization model is established by viewing the total entropy generation minimum at different flight phases as different objectives. Based on the basic multi-objective particle swarm optimization algorithm, an improved algorithm is proposed through a jump and cluster operation, and a new global optimal position distribution method. The simulation results show the good performance of the algorithm. The proposed algorithm is used to compute the multi-objective optimization model, the obtained pareto optimal set has good convergence and diversity. It provide a new way for integrated optimization of aircraft systems.

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