ISSN 0253-2778

CN 34-1054/N

2014 Vol. 44, No. 4

Display Method:
Original Paper
An uplink resource allocation strategy in heterogeneous networks based on WLAN
WEN Chunyang, QIU Ling
2014, 44(4): 259-264. doi: 10.3969/j.issn.0253-2778.2014.04.001
WLAN can provide high data rates for users, which is an effective complement to traditional cells in heterogeneous networks. However, resource management in WLAN is different from the central allocation of cellular networks, where exist collision and performance anomaly. A maximizing utility function problem was formulated, which allowed for the collision and performance anomaly in WLAN. Due to the non-convexity of constraints, the problem could not be solved directly. Poisson approximation of binominal distribution and the relationship between user number and collision probability were used to transform it into a convex problem. A distributed algorithm was proposed to optimally allocate resources between networks. Simulation results show that it can significantly enhance system performance and improve the utilization of WLAN.
Design of the built-in LTE antenna of laptop computers for 4G communication
ZHU Xianbin, SUN Yufa
2014, 44(4): 265-269. doi: 10.3969/j.issn.0253-2778.2014.04.002
A coupled-fed shorted monopole with a planar inverted-F antenna(PIFA) feed structure as an effective radiator for eight-band LTE operation in the laptop computer was presented. The antenna used a 50 Ω coaxial cable to feed signal into PIFA branch, and thus the energy of PIFA branch was fed into the shorted monopole branch due to the coupling effect of the capacitors. The coupling of the two branches produced multiple resonant modes, broadening the antenna band. The measured results show that the efficiency of the proposed LTE antenna exceeds 47%, with a return loss of less than -6 dB. The advantages of the presented antenna include its simple structure, broadened bandwidth, easier manufacturing and lowered cost, compared with conventional LTE antennas.
A background subtraction algorithm based on biological vision characteristics
QIAN Sheng, ZHANG Chenbin, CHEN Zonghai, WANG Zhiling
2014, 44(4): 270-277. doi: 10.3969/j.issn.0253-2778.2014.04.003
For the problem of how to build a robust background model and update the background model, a background subtraction algorithm based on biological vision characteristics combined with the ViBe algorithm was proposed. Firstly, utilizing the extrinsic nearsightedness characteristic of the frogs visual system, the meaning of a pretreatment method called “region fuzzy” and its implementation were described. Then, considering the characteristics of color cognition by humans, a measurement criterion for color difference based on Webers law in the LUV color space was given. Finally, specific implementations of the algorithm were introduced from three main aspects: Background modeling, foreground detection and background model updating. Experimental results show that this algorithm can improve the accuracy of moving object detection.
Study on pulse transmission delay of Pockels Cell feedforward driving source applied to photon modulation
LANG Jiahong, JANG Shunli, FENG Deren, XU Bo, WANG Shixiang, LIANG Hao, CHEN Wei, YONG Hailin
2014, 44(4): 278-284. doi: 10.3969/j.issn.0253-2778.2014.04.004
A Pockels Cell feedforward driving source based on DC modulation was proposed, which was applied to photon modulation. Aiming at the scattering effect of distribution parameters on wave propagation in circuit, an equivalent model circuit was built to simulate the pulse wave transmission in circuit and the influence of the scattering effect of distributed parameters on the triggered flow of the power switching device was analyzed. It was found that the scattering effect of distributed parameters on the switching drive signal resulted in a slower front edge of the drive pulse, which prolonged the triggered flow delay of the power switching device and increased the rising edge of the power pulse, thus increasing the delay time of pulse transmission. Some methods, including driving circuit improvement, circuit wiring optimization, and augment of an LC network matching circuit, were adopted to improve drive pulse transmission time delay. Experiment results indicate the pulse transmission delay of the improved circuit dropped remarkably from 300 ns to 100 ns in comparison with the original circuit.
Human activity recognition based on 3D skeletons and MCRF model
LIU Hao, GUO Li, YI bo, WANG Guanzhong
2014, 44(4): 285-291. doi: 10.3969/j.issn.0253-2778.2014.04.005
Considering the disadvantages of the traditional human activity recognition system, a human activity recognition system using an MCRF model and 3D skeletons was proposed. Its 3D skeleton data has less data and retains the key information, and the MCRF model has the advantage of being able to combine more features and utilizing adaptive contextual information. First, human activity was divided into global activity, arm activity, and leg activity. Several feature subsets were formed through more feature extraction. Then, CRF models were used on each feature subset to generate CRF units. Finally, all the CRF units were combined to produce the MCRF model which was utilized to recognize human activity. The experimental results indicate that the proposed method can improve detection accuracy.
Particle filter tracking based on feature-learning and feature-memory template update mechanism
LI Weiwei, ZHANG Chenbin, CHEN Zonghai, WANG Zhiling
2014, 44(4): 292-302. doi: 10.3969/j.issn.0253-2778.2014.04.006
The diversity of object motion and the complexity of background decrease the robustness of object tracking. Similarity of background colors, changes in illumination and object deformation lower the accuracy of the object template and the robustness of object tracking. To deal with this problem, a template update mechanism based on feature-learning and feature-memory was proposed. The algorithm built an object template library by preserving abundant information of the object. By matching the object with the object template library, the state of the object was obtained and the object was then tracked by particle filter. Experimental results show that the proposed method has better accuracy and robustness than the particle filter based on traditional object template update strategies.
Reconstruction characteristic and station layout optimization of distributed radar sparse imaging
WANG Shuo, CHEN Weidong
2014, 44(4): 303-309. doi: 10.3969/j.issn.0253-2778.2014.04.007
The relationship between target reconstruction and station layout in distributed radar sparse imaging system was studied. Based on the sparse imaging model of the distributed radar, the relationship between mutual coherence of measurement matrix and system parameters was derived. Furthermore, it was presented that the mutual coherence was decided only by unit station direction vector under the given conditions of radar parameters and imaging scene partition. Therefore, the cost function “minimization of mutual coherence” was utilized for station layout optimization. Simulation results are provided to demonstrate the performance improvement of the proposed method.
A multiprocessor architecture supporting dynamic partial reconfiguration
FENG Xiaojing, LI Xi, WANG Chao, CHEN Peng, ZHOU Xuehai
2014, 44(4): 310-316. doi: 10.3969/j.issn.0253-2778.2014.04.008
The intrinsic characteristics of embedded applications such as diversity and variability, together with their stringent requirements for computing performance, impose significant challenges on embedded system design. By providing a hardware/software co-design flow, an underlying communication interface, a parallel programming model and the relevant runtime environment, dynamic partial reconfigurable computing (DPR) technology was presented for service-oriented multiprocessor (SOMP) system. The DPR technology can effectively improve the system flexibility without performance loss, enabling the system to satisfy the requirements of more diverse embedded applications. An SOMP prototyping system has been implemented on the development board for the Xilinx Virtex-5 FPGA. A series of experiments were conducted and the results demonstrate the correctness and the resulting flexibility of the proposed architecture.
A false report filtering scheme based on neighbor watch for wireless sensor networks
ZHANG Shuguang, ZHOU Xuehai, YANG Feng, XU Jun
2014, 44(4): 317-324. doi: 10.3969/j.issn.0253-2778.2014.04.009
A false report filtering scheme based on neighbor watch was proposed, in which information from two-hop neighboring nodes was stored, which included IDs and MACs of T nodes from different zones. Each forwarding node sent an ACK message to its upstream node after sending a report to its downstream node. False reports generated with keys from other zones would be detected by the one-hop neighbors of the malicious node. Meanwhile, forwarding nodes and the Sink would verify the authenticity of other reports. Analysis and experimental results show that this scheme improves filtering efficiency significantly, thus reducing the impact of malicious nodes and extending the life of the sensor network.
A reconfigurable hardware-software iteration co-synthesis algorithm based on vertex position tree
LI Chunsheng, ZHOU Xuehai, ZENG Fangling, WANG Chao
2014, 44(4): 325-332. doi: 10.3969/j.issn.0253-2778.2014.04.010
In reconfigurable computing, more tasks can be executed at a higher speed in hardware by time multiplexing with the limited area resources. Meanwhile, it also brings new challenges to the traditional hardware-software codesign. For offline scheduling, centralized shared structure reconfigurable platform, the ICS-VPT (iteration co-synthesis based on vertex position tree) algorithm synthesized hardware-software partitioning, hardware placement and task scheduling to improve system performance: The VPT (vertex position tree) data structure was first proposed, which could find a placement position quickly with small storage space; The ICS (iteration co-synthesis) algorithm grouped tasks according to data dependence graph and obtained the hardware/software tasks priorities by combining the communication cost, thus obtaining a reasonable partitioning and scheduling. Experimental results show that the ICS-VPT algorithm maintains a lower level of system running time by means of efficient reconfigurable resource management and flexible communication cost handling.
Study of electromagnetic protection based on high repetition rate EMP simulator control system
MA Lihua, FENG Deren, LI Xiaolong, HE Shanhong, CHE Wenxuan, XIONG Ying
2014, 44(4): 333-338. doi: 10.3969/j.issn.0253-2778.2014.04.011
High repetition rate EMP simulator is a high-power radiation source, but it produces a very strong electromagnetic interference(EMI) while in operation. To combat this interference, an electromagnetic protection scheme based on DSP control, combining hardware protection with software reinforcement, was proposed. A bounded-wave simulator system was used to prove the feasibility of the scheme. The experimental results show that the DSP system using hardware shield and software reinforcement technology can work well near the EMP simulator, and that it is feasible and has strong anti-jamming capacity.
Dynamic robust path following control of a wheeled mobile robot with uncertainties
GUO Nana, LI Zong, LIAO Xiaobing
2014, 44(4): 339-344. doi: 10.3969/j.issn.0253-2778.2014.04.012
A geometric function of target path was used to model tracking error, turning the path following problem under study into one of output regulation which was solved by backstepping a kinematic-dynamic mixed control law derived from input-output linearization method based on the dynamic model of the system. A Lyapunov-like method was used to derive parameter adaptation laws that ensured the asymptotical tracking of the target path despite the unknown constant parameters. Asymptotical convergence of the robot to the target path was proved and the numerical simulation results show the effectiveness of the control scheme.