To overcome the obstacle of the fascinating relation in predicting animal phenotype value, we have developed a neural network model to detect the complex non-linear relationships between the genotypes and phenotypes a...To overcome the obstacle of the fascinating relation in predicting animal phenotype value, we have developed a neural network model to detect the complex non-linear relationships between the genotypes and phenotypes and the possible interactions that cannot be expressed with equations. In this paper, back-propagation neural network is used to discuss the influences of different allele frequencies on estimating the polygenic phenotype value. To ensure the precision of prediction, normalization was needed to train the prediction model. The results show that back-propagation artificial neural networks can be used to predict the phenotype value and perform very well in allele frequency from 0.2 to 0.8, when the allele frequency is very small （less than 0.2） or big （more than 0.8）; however, the prediction model was not reliable and the predicted value should be carefully tested.展开更多
The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network...The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To minimize the demanded radio resources for multicast services in the LTE, a novel mode switch (MS) between SFN and PTP for multicast services is proposed. MS takes into account PTP mode for multicast services and the switch is based on the handover threshold. To solve the minimization problem, MS adapts the handover threshold with the difference in the demanded radio resources between SFN mode and PTP mode for multicast services. The simulation results show that the proposed MS achieves less demanded radio resources than SFN mode for all the multicast services.展开更多
单频网(Single Frequency Network,SFN)的运行对发射机的同步提出极高的技术要求,任何同步误差都可能对网络性能产生不利影响。首先分析SFN中时间、频率和相位同步误差的定义与分类,其次探讨其对关键性能指标的影响机理,并量化同步误差...单频网(Single Frequency Network,SFN)的运行对发射机的同步提出极高的技术要求,任何同步误差都可能对网络性能产生不利影响。首先分析SFN中时间、频率和相位同步误差的定义与分类,其次探讨其对关键性能指标的影响机理,并量化同步误差对覆盖范围和信道容量的削弱程度,最后针对同步误差的成因提出提高授时源精度、优化参考时钟选型、改进同步跟踪环路设计及多径信号抑制等策略。展开更多
单频网(Single Frequency Network,SFN)技术通过多个发射站点在同一频率上同步传输相同信号,有效解决了复杂地形条件下的覆盖难题。以某山区城市地面数字电视SFN覆盖工程为例,分析基于SFN技术的地面数字电视覆盖方案。该工程针对地形起...单频网(Single Frequency Network,SFN)技术通过多个发射站点在同一频率上同步传输相同信号,有效解决了复杂地形条件下的覆盖难题。以某山区城市地面数字电视SFN覆盖工程为例,分析基于SFN技术的地面数字电视覆盖方案。该工程针对地形起伏大、阴影区域多、信号传播路径复杂等特点,采用了精确的发射站点空间配置方案,设计了适应性强的信号功率分配算法,建立了完善的覆盖边界协调控制机制,并对SFN系统关键参数进行了全面优化。工程实施后的测试结果表明,SFN技术显著提升了地面数字电视的覆盖性能,有效消除了传统覆盖盲区,为类似地形条件下的数字电视广播网络建设提供了成功范例。展开更多
The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we prop...The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we propose a multicast resource allocation scheme based on limited feedback to maximize the total rate while guaranteeing the quality of service (QoS) requirement of real-time services. In this scheme, we design a user feedback control algorithm to effectively reduce feedback load. The algorithm determines to which base stations the users should report channel state information. We then formulate a joint subcarrier and power allocation issue and find that it has high complexity. Hence, we first distribute subcarriers under the assumption of equal power and develop a proportional allocation strategy to achieve a tradeoff between fairness and QoS. Next, an iterative water-filling power allocation is proposed to fully utilize the limited power. To further decrease complexity, a power iterative scheme is introduced. Simulation results show that the proposed scheme significantly improves system performance while reducing 68% of the feedback overhead. In addition, the power iterative strategy is suitable in practice due to low complexity.展开更多
多发射机间的同步误差是制约单频网(Single Frequency Network,SFN)信号覆盖质量的关键因素。围绕相位编码技术的特性,分析SFN系统对同步误差的敏感机制,阐述相位编码在多径环境下相较于传统方法的抗干扰优势。通过建立多分量叠加的相...多发射机间的同步误差是制约单频网(Single Frequency Network,SFN)信号覆盖质量的关键因素。围绕相位编码技术的特性,分析SFN系统对同步误差的敏感机制,阐述相位编码在多径环境下相较于传统方法的抗干扰优势。通过建立多分量叠加的相位扰动模型,提出基于双环控制结构的同步误差联合估计方法,设计一种融合变步长机制的自适应均衡补偿算法,验证了相位信息在误差传播抑制中的核心作用。展开更多
在广播电视信号传输体系中,多频网(Multi Frequency Network,MFN)与单频网(Single Frequency Network,SFN)是两类核心覆盖架构。其技术特性直接影响频谱资源利用效率、信号覆盖质量、传输成本及内容灵活性。基于此,梳理两类网络的核心特...在广播电视信号传输体系中,多频网(Multi Frequency Network,MFN)与单频网(Single Frequency Network,SFN)是两类核心覆盖架构。其技术特性直接影响频谱资源利用效率、信号覆盖质量、传输成本及内容灵活性。基于此,梳理两类网络的核心特点,从频谱效率、覆盖连续性、设备成本、接收效果及内容适配性等维度展开对比,结合不同应用场景提出网络架构选型建议,为广播电视传输网络的规划、建设及优化提供清晰的决策依据,助力平衡“高效覆盖”与“需求适配”的双重目标。展开更多
基金Supported by the Scientific Research Starting Foundation for Doctors, Henan Institute of Science and Technology of China
文摘To overcome the obstacle of the fascinating relation in predicting animal phenotype value, we have developed a neural network model to detect the complex non-linear relationships between the genotypes and phenotypes and the possible interactions that cannot be expressed with equations. In this paper, back-propagation neural network is used to discuss the influences of different allele frequencies on estimating the polygenic phenotype value. To ensure the precision of prediction, normalization was needed to train the prediction model. The results show that back-propagation artificial neural networks can be used to predict the phenotype value and perform very well in allele frequency from 0.2 to 0.8, when the allele frequency is very small （less than 0.2） or big （more than 0.8）; however, the prediction model was not reliable and the predicted value should be carefully tested.
基金Sponsored by the National Key Technology R&D Program of China ( Grant No. 2010ZX03003-001-01)Fundamental Research Funds for the Central Universities
文摘The multimedia broadcast and multicast services (MBMS) in 3GPP LTE is characterized by multicast broadcast single frequency network (MBSFN) operation. The multicast services are transmitted by single frequency network (SFN) mode, and the unicast services are delivered with point-to-point (PTP) mode. To minimize the demanded radio resources for multicast services in the LTE, a novel mode switch (MS) between SFN and PTP for multicast services is proposed. MS takes into account PTP mode for multicast services and the switch is based on the handover threshold. To solve the minimization problem, MS adapts the handover threshold with the difference in the demanded radio resources between SFN mode and PTP mode for multicast services. The simulation results show that the proposed MS achieves less demanded radio resources than SFN mode for all the multicast services.
文摘单频网(Single Frequency Network,SFN)的运行对发射机的同步提出极高的技术要求,任何同步误差都可能对网络性能产生不利影响。首先分析SFN中时间、频率和相位同步误差的定义与分类,其次探讨其对关键性能指标的影响机理,并量化同步误差对覆盖范围和信道容量的削弱程度,最后针对同步误差的成因提出提高授时源精度、优化参考时钟选型、改进同步跟踪环路设计及多径信号抑制等策略。
文摘单频网(Single Frequency Network,SFN)技术通过多个发射站点在同一频率上同步传输相同信号,有效解决了复杂地形条件下的覆盖难题。以某山区城市地面数字电视SFN覆盖工程为例,分析基于SFN技术的地面数字电视覆盖方案。该工程针对地形起伏大、阴影区域多、信号传播路径复杂等特点,采用了精确的发射站点空间配置方案,设计了适应性强的信号功率分配算法,建立了完善的覆盖边界协调控制机制,并对SFN系统关键参数进行了全面优化。工程实施后的测试结果表明,SFN技术显著提升了地面数字电视的覆盖性能,有效消除了传统覆盖盲区,为类似地形条件下的数字电视广播网络建设提供了成功范例。
基金supported by the National Natural Science Foundation of China (Nos. 60972076 and 61072052)the National Science and Technology Major Project, China (No. 2010ZX03003-004-03)
文摘The single frequency network (SFN) can provide a multimedia broadcast multicast service over a large coverage area. However, the application of SFN is still restricted by a large amount of feedback. Therefore, we propose a multicast resource allocation scheme based on limited feedback to maximize the total rate while guaranteeing the quality of service (QoS) requirement of real-time services. In this scheme, we design a user feedback control algorithm to effectively reduce feedback load. The algorithm determines to which base stations the users should report channel state information. We then formulate a joint subcarrier and power allocation issue and find that it has high complexity. Hence, we first distribute subcarriers under the assumption of equal power and develop a proportional allocation strategy to achieve a tradeoff between fairness and QoS. Next, an iterative water-filling power allocation is proposed to fully utilize the limited power. To further decrease complexity, a power iterative scheme is introduced. Simulation results show that the proposed scheme significantly improves system performance while reducing 68% of the feedback overhead. In addition, the power iterative strategy is suitable in practice due to low complexity.
文摘多发射机间的同步误差是制约单频网(Single Frequency Network,SFN)信号覆盖质量的关键因素。围绕相位编码技术的特性,分析SFN系统对同步误差的敏感机制,阐述相位编码在多径环境下相较于传统方法的抗干扰优势。通过建立多分量叠加的相位扰动模型,提出基于双环控制结构的同步误差联合估计方法,设计一种融合变步长机制的自适应均衡补偿算法,验证了相位信息在误差传播抑制中的核心作用。
文摘在广播电视信号传输体系中,多频网(Multi Frequency Network,MFN)与单频网(Single Frequency Network,SFN)是两类核心覆盖架构。其技术特性直接影响频谱资源利用效率、信号覆盖质量、传输成本及内容灵活性。基于此,梳理两类网络的核心特点,从频谱效率、覆盖连续性、设备成本、接收效果及内容适配性等维度展开对比,结合不同应用场景提出网络架构选型建议,为广播电视传输网络的规划、建设及优化提供清晰的决策依据,助力平衡“高效覆盖”与“需求适配”的双重目标。
