Zhiyuan Shi

Layered security approach in LTE and simulation

The Third Generation Partnership Project (3GPP) has been specifying the standards of Long Term Evolution (LTE) for 3G radio access. The security concerns in wireless networks might have prevented its further widespread adoption. Layered security approach in LTE is analyzed, an EAP method EAP-Archie used for authentication and ciphering is introduced in this paper. EAP-Archie which embedded in Open Diameter environment is simulated. The result shows it can authentication successfully.

Performance of Secondary Access in the Spectrum Sharing System with Call Admission Control Strategy

Recently, secondary usage methods have been proposed to utilize the spectrum holes in the licensed spectrum bands. In our previous works [6], based on the concept of spectrum pooling, an opportunistic spectrum sharing system with heterogeneous secondary users was proposed. In this paper, a spectrum sharing system with call admission control strategy is proposed. By analyzing the forced termination probability and blocked probability of secondary users, the QoS guarantee for secondary access is insightful studied. Numerical results show that the proposed call admission strategy can increase the throughput of secondary users significantly, as well as guarantee the access priority of primary user.

Software-defined Radio based On Cortex-A9

This paper presents an implementation of Software-defined Radio (SDR) system over ARM Cortex-A9 processor. Compared with conventionally used general purpose CPU, e.g. X86 CPU, ARM processors have advantages in both price and power consumption under the same computing capability. Two basic issues of SDR over ARM are investigated: the real-time operation and signal processing efficiency. For the former issue, we select the Linux-based real-time operating system Xenomai, which is built on Cortex-A9 platform. Testing results show that the performance of Xenomai on Cortex-A9 meets the real-time requirement of SDR. Furthermore, the NEON technology of Cortex-A9 is used to optimize the complex signal processing algorithms in communication systems. Soft Demodulation is taken as an example for the optimization, and the experimental results are provided to show the improvement of signal processing efficiency.

Research on quality assessment metric based on H.264/AVC bitstream

No-reference(NR) video quality metrics are more practical in real-time applications compared to full-reference(FR) metrics. This contribution proposed a No-reference video quality assessment metric based on H.264/AVC bitstream through extracting features from the H.264/AVC encoded bitstream. After the extraction of the features which are very important for video quality assessment, we use Partial Least Squares Regression(PLSR) to calculate the weights of them. Then a quality prediction model is also proposed. During the experiments, the results show that our NR metric has low computing complexity. Finally, compared to subjective assessment, we find that there is a high correlation between quality prediction and the actual quality of 0.95.

Frequency Reconfigurable Antenna with Micromechanical Patch

The frequency reconfigurable antenna normally designed with MEMS switch is flexible to change its operating frequency. However, when the operating frequency is up to millimeter wave or even higher, this kind MEMS switching operation will deteriorate performance of antenna. A novel frequency reconfigurable antenna is designed with micromechanical patch moving via electrostatic force. As the bias voltage between patch and antenna is changed, it makes the patch to move and the antenna operating frequency changes too. Its operating mode is equivalent to changing the relatively permittivity of antenna substrate. Architecture of this kind of micromechanical patch antenna is presented and its principle is analyzed. With the results of parameter analysis, the desire performance of antenna can be designed perfectly, and the simulation result is coincident with the prospective analysis.

Multipath routing based adaptive multi-channel MAC protocol for wireless mesh networks

In this paper, we propose an anycast mechanism which can adaptively choose the best next-hop to forward packets during the announcement traffic indication map (ATIM) window of multi-channel medium access control (MMAC) protocol. In order to improve the performance of networks by reducing transmission retries and packet drop probabilities, we also propose a multipath extension of AODV routing protocol to provide the adaptive MMAC protocol with multiple next-hop links. Simulation results show that the proposed scheme provides better performance, both in regular and random scenario of mesh network model.

Interference alignment based on antenna selection for massive MIMO system

This paper presents an anti-interference method of massive multi-input multi-output (Massive MIMO) based on antenna selection. Assume that both the base station (BS) and mobile station (MS) can acquire real-time channel state information (CSI), the transmitter and receiver select a set of antennas to transmit signals according to the optimization criterion of maximum channel capacity using an improved distributed antenna selection algorithm with low complexity. After antenna selection, the interference from different spatial data flow is then aligned in one direction or into one subspace, leaving most of the spatial degrees of freedom for useful signals. Simulation results show that the proposed scheme achieves considerably better performance than the zero-forcing (ZF) precoding solution, this advantage is especially obvious in a high SNR regime.

Multifractal slope feature based wireless devices identification

Cognitive Radio (CR) is a promising technology for alleviating spectrum shortage problem. However, with the realization of CR, new security issues are gradually emerging, like Primary User Emulation (PUE) attack. This paper incorporates transient-based identification into cognitive radio network (CRN) to defend against the PUE attacks. A method of extracting transient envelope features for wireless devices identification based on multifractal has been presented. Utilizing the joint fingerprint features of multifractal slope and polynomial fitting for wireless devices identification, the results show that the recognition performance is greatly improved.

Material Intelligent Identification Based on Hyperspectral Imaging and SVM

With the rapid development of economic globalization, the method of material identification in customs is behind the times. The higher identification efficiency is required by the increase of imports. In this paper, a new hyperspectral imaging intelligent material identifying system based on instantly scanning technique is proposed. The system is investigated by an identification experiment with 5 kinds of flour participated. The spectrum imaging device adopted is from MeiyaPico coded CP-2000B. 250 groups of spectral feature (400 to 750 nm) data are collected by the device. Sample sets retreated by removing the envelope using the radial basis function for kernel are transformed into a subspace. The database building and the identification are accompanied by SVM classification algorithm. In the experiments, the accuracy of system proposed is above 95%.

A new Reduced-Reference Image Quality Assessment Method based on SSIM

Because human visual perception is highly adapted for extracting structural information from a scene, but the existing SSIM index is a full reference method which needs entire information of reference images. In this paper, we develop a reduced reference SSIM method and evaluate its performance through a set of assessment criteria, as well as comparison to both EPSNR and SSIM methods on a database of images compressed with JPEG and JPEG2000.