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Search Results: 1 - 10 of 98529 matches for " CHEN Qian-bin "
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Reduction of Feedback Based-on User Traffic Rate in OFDM Relay System
Qian-Bin Chen,Guang-Jian Jiang,Lun Tang
International Journal of Wireless and Microwave Technologies , 2011, DOI: 10.5815/ijwmt.2011.05.05
Abstract: In order to reduce feedback while maintaining user performance in multiuser orthogonal frequency division multiplexing (OFDM) relay system, feedback mechanism based on user traffic rate is proposed. From the aspects of feedback outage probability, user weighted channel gain related to user traffic rate is compared with the system threshold. The higher user traffic rate is, the bigger the user traffic weight becomes. So the high traffic rate user has greater probability to be fed back, which can support different traffic rate. Simulation results show that the proposed feedback mechanism can bring more feedback sub-carriers to the user with high traffic rate.
Power Allocation for Balancing Spectrum Efficiency and Power Consumption in Cognitive Relay Networks
Lun Tang,Qing Li,Qian-Bin Chen
International Journal of Wireless and Microwave Technologies , 2011, DOI: 10.5815/ijwmt.2011.05.06
Abstract: In order to guarantee the QoS requirement of secondary users and not to affect the outage probability of primary user in cognitive relay networks, we propose two optimal power allocation models: (1) maximizing the transmission rate of secondary users; (2) minimizing the total power consumption. Theory analysis shows that two optimal power allocation models conflict between spectrum efficiency and power consumption. Furthermore, an optimal power allocation model which joints the transmission rate and the total power consumption in cognitive relay networks is proposed. By using the Lagrangian method, the optimization algorithm for this model is designed. The proposed algorithm can achieve the trade-off between the transmission rate and the total power consumption by varying the weight. Simulation results show that the proposed algorithm can effectively adjust the transmission rate and the total power consumption of secondary users.
Research on handover algorithm in TD-SCDMA communication trunking system

TANG Hong,YU Xiao,CHEN Qian-bin,

计算机应用研究 , 2011,
Abstract: In order to choose handover-target-cell quickly and accurately, and improve the success rate of handover, this paper first presented a theory of determination about target-cell, which based on Grey Relational Analysis method, and its simulation verification. Second, it improved the handover algorithm based on the mobile velocity, and then compared the improved algorithm with traditional algorithm by simulation. At last, judging from the Received Signal Code Power and the handover times, it draws a conclusion that the improved algorithm is better than traditional algorithm.
Research on cooperative ARQ for two-hop and two-relay system

XIONG Ying,TANG Lun,CHEN Qian-bin,

计算机应用研究 , 2010,
Abstract: The paper proposed a new transmission scheme in cooperative communication system based on best relay selection: cooperative ARQ scheme for two-hop and two-relay. The scheme was a tradeoff between transmission delay and efficiency. The analysis of theory and simulation results show that, under time correlated Rayleigh fading channel, cooperative ARQ scheme for two-hop and two-relay can give the best performance gain compared with single relay cooperative ARQ system and two relay cooperative system, not only when the qualities of source and relay are good, but also when there is a bad fading in the link of source to relay.
Opportunistic relay selection scheme based on adaptively quantized channel state information

LI Yan,TANG Lun,CHEN Qian-bin,

计算机应用研究 , 2010,
Abstract: In order to deal with the system overhead problem induced by transmit quantized bits of the first hop channel state information for destination to obtain global channel state information, this paper proposed the relay selection scheme based on adaptively transmitting the quantization bits of instantaneous channel state information. In the improved scheme, the candidate relayed transmit the quantized bits of the first hop channel state information only when the instantaneous channel condition was better than the threshold which was set in advance. Simulation result shows that the new scheme can improve the bit utilize efficiency and at the same time has little influence on the bit error rate of the system. Moreover, as the number of candidate relays increases from three to five, the appropriate threshold ranges from 0.267 1 to 0.575 6, this result shows that the improved scheme has robustness performance.
Architecture of GMPLS-based optical burst switching networks and its performance simulations

HUANG Qiong,CHEN Qian-bin,LIU Xiang,

重庆邮电大学学报(自然科学版) , 2007,
Abstract: 研究了如何将多协议标签(GMPLS)与光突发交换"*+)#高效地结合及协调地工作!使GMPLS为*+)网 络控制和管理提供良好的技术手段,给出了基于GMPLS的*+)网络结构模型!讨论了GMPLS-Based OBS网络 中动态信道共享策略,并阐述了控制信息与数据传输机制和GMPLS-Based OBS网络节点功能结构。针对性地讨 论了GMPLS在路由、信令、链路管理协议上进行增强和扩展等问题。通过仿真对DS-OBS,GMPLS-based DS-OBS 和GMPLS-TE based ds-OBS等3种
Short packet first scheduling for variable length optical packet switching

LIU Huan-lin,CHEN Qian-bin,

重庆邮电大学学报(自然科学版) , 2007,
Abstract: 为了解决因可变长光分组交换的输出队头阻塞问题造成分组的平均排队时延增加,分析了可变长分组的 长度分布特点,提出了基于抢占方式的短包优先调度(PSPF)算法,以减少分组在输入排队中的平均等待时间。在 PSPF算法中,短包可以抢占长包的传输时间而获得优先服务。分析和仿真结果表明:当到达业务负载较低或中等 程度时,采用PSPF算法可使短包的平均排队时延接近0,所有分组的平均等待时延减小,还保证了实时性TCP业 务较低的平均等待时延。
Cross Layer Design and Performance Analysis of HARQ Schemes in Multi-Relay Networks
Cui-Qin Dai,Li Jiang,Qian-Bin Chen,Guang-Yu Wang
International Journal of Wireless and Microwave Technologies , 2011, DOI: 10.5815/ijwmt.2011.05.10
Abstract: We propose a cross-layer design combining adaptive modulation and coding (AMC) at the physical layer with a hybrid automatic repeat request (HARQ) protocol at the data link layer in multi-relay networks with imperfect channel state information (CSI). Based on a simple and distributed relay selection strategy, we derive the closed-form expressions for performance metrics such as average packet loss rate (PER) and spectral efficiency; and further formulate an optimization model to maximize the spectral efficiency under the target PER constraint. The numerical results show that the average PER is lower and the spectral efficiency is higher with the number of the relay increasing.
Cross-Layer Design of Combining HARQ with Adaptive Modulation and Coding for Nakagami-m Fading Channels
Cui-Qin Dai,Yu Rao,Li Jiang,Qian-Bin Chen
Journal of Communications , 2012, DOI: 10.4304/jcm.7.6.458-463
Abstract: In this paper, we propose a cross-layer design which combines adaptive modulation and coding (AMC) at the physical layer with a hybrid automatic repeat request (HARQ) protocol at the data link layer to minimize the packet error rate (PER) and maximize the spectral efficiency. By using Markov model to predict the channel condition of next frame according to the second order statistics characteristics of the former frame, we calculate the conditional probability density function and joint probability density function of signal to noise ratio (SNR). Further, we derive the packet error rate and average spectral efficiency in closed-form for transmission over Nakagami-m fading channels. Numerical results show that the proposed scheme can obtain lower PER and higher spectral efficiency compared with traditional HARQ protocols. The cross-layer design scheme combing type-III HARQ with AMC can achieve the highest spectral efficiency and the lowest PER than type-I HARQ and type-II HARQ.
Analysis of energy detection based spectrum sensing in noise of uncertain power

CUI Tai-ping,CHEN Qian-bin,SHEN Bin,

重庆邮电大学学报(自然科学版) , 2008,
Abstract: Cognitive radio (CR) is viewed as a promising technology to improve spectrum utilization via negotiated or opportunistic spectrum sharing without interference to primary or licensed users,and the key challenge of the new system implementation is the reliable detection of presence of primary users.Energy detection based spectrum sensing is quite simple and is able to locate spectrum-occupancy information quickly,but it has some limitations such as vulnerability to noise.Energy detection has been studied widely in recent years,but the effect of noise power uncertainty is seldom evaluated in relevant literatures,especially in fading channels.This paper presents another look at the problem of energy detection of unknown signals in noise of uncertain power.Worst case perform ance bounds are provided as a function of input signal-to-noise ratio(SNR),time-bandwidth product(TW) and peak-to-peak noise uncertainty(U).Even with a small fraction of noise-level uncertainty,the performance of detection degrades heavily.An even worse result than is indicated by the standard result is given in Rayleigh fadingchannels.
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