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Yi H.,Shanghai JiaoTong University | Zou J.,Shanghai JiaoTong University | Luo H.,Shanghai JiaoTong University | Yu H.,Shanghai JiaoTong University | Ma J.,Leadcore Technology Co.
2011 International Conference on Wireless Communications and Signal Processing, WCSP 2011 | Year: 2011

This paper addresses the problem of joint design of user precoders and receivers as well as the relay precoder based on the minimum mean-square-error (MMSE) criterion in the multi-user amplify-and-forward (AF) two-way multiple-input multiple-output (MIMO) relay systems with analog network coding (ANC). By decoupling the original highly nonconvex problem into three sub-problems, we propose an iterative algorithm to repeatedly optimize precoders and receivers. The convergence of the algorithm is ensured since the updated solution is optimal to each sub-problem. In addition, a novel channel switching technique at the relay node is implemented as means of exploring different local optimal solutions to further improve the system performance. Numerical simulation results demonstrate that the proposed iterative algorithm outperforms other algorithms in terms of both bit error rate (BER) and mean square error (MSE). © 2011 IEEE.

Wang Y.,Southwest Jiaotong University | Sun J.,Southwest Jiaotong University | Wang S.,University of Sichuan | Gao H.,Leadcore Technology Co.
Proceedings of 2011 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference, CSQRWC 2011 | Year: 2011

In intelligent surveillance, how to calibrate camera in absence of calibrated objects or scene's structure information or camera's motion information, is a significant topic. This paper proposes a novel approach based on vertical objects using 4∼5 positions labeled by human in video sequences with knowing height and obtains vertical vanishing point and plane vanishing line. Considering the importance of the vertical vanishing point, the plane vanishing line and the sensitivity of those two to noise, an optimal algorithm to vanishing point and line is proposed; Then according to the properties of vanishing point and vanishing line being function of camera parameters, all the intrinsic and extrinsic parameters are solved; Finally, this paper shows the optimal number and position of human in camera field. Both computer simulation and real data validate robustness and effectiveness of the algorithm. © 2011 IEEE.

Xu P.,Shanghai JiaoTong University | Gu S.,Shanghai JiaoTong University | Gao L.,Shanghai JiaoTong University | Yu H.,Shanghai JiaoTong University | And 3 more authors.
IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference | Year: 2010

In this paper, we consider a scenario where multiple secondary users search for idle frequency bands in a spectrum consisting of multiple channels. The state of each channel is modeled as a discrete-time Markov process. In each time slot, one secondary user(SU) chooses one channel to sense and decides whether to use the channel based on the sensing result. When there is only one SU, former work has proved that a myopic policy maximizing the current reward is optimal when the channel state transitions are positively correlated over time. In this paper, we extend the myopic policy to multiple-SU scenario. We propose and analyze two approaches that make use of the myopic policy more efficiently when multiple SUs exist. Copyright © 2010 ACM.

Jinhua L.,Beijing University of Posts and Telecommunications | Yahong W.,Leadcore Technology Co. | Yahong W.,China Academy of Telecommunication Technologies | Shuai D.,University of Science and Technology Beijing
China Communications | Year: 2010

As the technology of IP Fast Rerouting (FRR) become mature and the related methods and specification such as RFC5286 accepted as standard, it is expected that IP FRR will be deployed gradually and will enhance the survivability of IP network. This paper presents a different method for computing the Loop-free Alternate Interfaces. The new algorithm can be referred as "Next-Hop Cost Decrease (NHCD)" criterion. Compared with the RFC5286 LFA method, NHCD can handle both the simultaneous link failure and node failure, including multi-link failures. It has less computational complexity and can be used uniformly in the Traffic Engineering and Network Recovery. However, NHCD is somewhat lower than the LFA method on recovery ratio of single link failure. After a formal description of NHCD criterion and a proof of loop-free alternates, the paper presents the simulation results of NHCD.

Li P.,Fudan University | Zhu Y.,Fudan University | Wang Z.,Fudan University | Wang N.,Leadcore Technology Co.
2010 Global Mobile Congress, GMC'2010 | Year: 2010

Single carrier frequency division multiple access (SC-FDMA), which combines the single carrier frequency domain equalization (SC-FDE) and frequency division multiple access (FDMA) techniques is a promising broadband wireless access scheme. However, previous research has shown that the peak-to-average power ratio (PAPR) of SC-FDMA is high especially in the case of localized subcarrier mapping. In this paper, we simulate and analyze the PAPR for SC-FDMA with two subcarrier mapping schemes known as Localized FDMA (LFDMA) and Interleaved FDMA (IFDMA) respectively, and evaluate the PAPR performance of users assigned on different subcarriers in LFDMA. To reduce the PAPR, we propose an efficient clipping-based PAPR reduction algorithm. Simulation results show that with a small degradation in the system bit error rate (BER) performance the proposed scheme can achieve around 2dB PAPR reduction for LFDMA. © 2010 IEEE.

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