上行链路(Uplink,UL)和下行链路(Downlink,DL)解耦是第六代移动通信网络(the sixth-generation mobile communication networks,6G)的一个关键特性,可以增强覆盖范围、能源效率和频谱效率。然而,6G中的上下行链路解耦技术指标分析在很...上行链路(Uplink,UL)和下行链路(Downlink,DL)解耦是第六代移动通信网络(the sixth-generation mobile communication networks,6G)的一个关键特性,可以增强覆盖范围、能源效率和频谱效率。然而,6G中的上下行链路解耦技术指标分析在很大程度上仍然是空白的。讨论了上下行传输中用户接入方案,推导了多种情况下的下行链路接入概率。在此基础上,进一步推导了上行链路和下行链路中断概率表达式,且利用柯西-施瓦茨不等式分析了上行链路中断概率的下界。仿真结果表明,推导的性能解析表达式与蒙特卡罗仿真结果相吻合,中等信噪比时,理论下界与真实值之间的间隙很小。展开更多
针对非理想信道状态信息(CSI,channel state information)下的多小区下行时分复用(TDD,time division multiplexing)大规模多入多出(MIMO,multiple-input multiple-output)系统,研究了基于服务质量(QoS,quality of service)的发射功率...针对非理想信道状态信息(CSI,channel state information)下的多小区下行时分复用(TDD,time division multiplexing)大规模多入多出(MIMO,multiple-input multiple-output)系统,研究了基于服务质量(QoS,quality of service)的发射功率和小区间泄露功率最小的波束成形问题。首先,将目标问题近似成凸优化问题,然后,利用上下行链路对偶性,提出一种内外层迭代算法。数值分析结果表明,所提算法与其他几种典型的多小区波束成形算法相比,在算法复杂度和能量效率性能指标方面具有明显优势。展开更多
视频监控业务能够对智能电网中输电线路、变电站等进行监控,实现高效的电力网络运维以及安全生产。考虑视频监控业务的实时性要求、多维用户体验(Quality of Experience,QoE)指标联合优化需求以及资源配置的不协调,文章提出了视频监控...视频监控业务能够对智能电网中输电线路、变电站等进行监控,实现高效的电力网络运维以及安全生产。考虑视频监控业务的实时性要求、多维用户体验(Quality of Experience,QoE)指标联合优化需求以及资源配置的不协调,文章提出了视频监控业务上下行资源联合分配方法。在该方法中,首先联合考虑上行链路资源、下行链路资源以及计算资源的分配,以多维QoE指标(包括视频监控业务的切换频率和卡顿等)优化为目标,建立了基于视频内容处理低时延保障的问题;其次设计了基于凸优化的资源分配搜索方法对所提问题进行求解,最后对所提方案性能进行了仿真评估。展开更多
Traditional cellular network requires that a user equipment(UE) should associate to the same base station(BS) in both the downlink(DL) and the uplink(UL). Based on dual connectivity(DC) introduced in LTE-Advanced R12,...Traditional cellular network requires that a user equipment(UE) should associate to the same base station(BS) in both the downlink(DL) and the uplink(UL). Based on dual connectivity(DC) introduced in LTE-Advanced R12, DL/UL decouple access scheme has been proposed, which is especially suitable for heterogeneous networks(Het Nets). This paper is the pioneer to take the DL/UL decouple access scheme into consideration and develop a novel resource allocation algorithm in a two-tier Het Net to improve the total system throughput in the UL and ease the load imbalance between macro base stations(MBSs) and pico base stations(PBSs). A model is formulated as a nonlinear integer programming, and the proposed algorithm is a sub-optimal algorithm based on the graph theory. First, an undirected and weighted interference graph is obtained. Next, the users are grouped to let users with large mutual interferences to be assigned to different clusters. Then, the users in different clusters are allocated to different resource blocks(RBs) by using the Hungarian algorithm. Simulation results show that the proposed algorithm can provide great promotions for both the total system throughput and the average cell edge user throughput and successfully ease the load imbalance between MBSs and PBSs.展开更多
In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal proce...In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.展开更多
文摘上行链路(Uplink,UL)和下行链路(Downlink,DL)解耦是第六代移动通信网络(the sixth-generation mobile communication networks,6G)的一个关键特性,可以增强覆盖范围、能源效率和频谱效率。然而,6G中的上下行链路解耦技术指标分析在很大程度上仍然是空白的。讨论了上下行传输中用户接入方案,推导了多种情况下的下行链路接入概率。在此基础上,进一步推导了上行链路和下行链路中断概率表达式,且利用柯西-施瓦茨不等式分析了上行链路中断概率的下界。仿真结果表明,推导的性能解析表达式与蒙特卡罗仿真结果相吻合,中等信噪比时,理论下界与真实值之间的间隙很小。
文摘针对非理想信道状态信息(CSI,channel state information)下的多小区下行时分复用(TDD,time division multiplexing)大规模多入多出(MIMO,multiple-input multiple-output)系统,研究了基于服务质量(QoS,quality of service)的发射功率和小区间泄露功率最小的波束成形问题。首先,将目标问题近似成凸优化问题,然后,利用上下行链路对偶性,提出一种内外层迭代算法。数值分析结果表明,所提算法与其他几种典型的多小区波束成形算法相比,在算法复杂度和能量效率性能指标方面具有明显优势。
文摘视频监控业务能够对智能电网中输电线路、变电站等进行监控,实现高效的电力网络运维以及安全生产。考虑视频监控业务的实时性要求、多维用户体验(Quality of Experience,QoE)指标联合优化需求以及资源配置的不协调,文章提出了视频监控业务上下行资源联合分配方法。在该方法中,首先联合考虑上行链路资源、下行链路资源以及计算资源的分配,以多维QoE指标(包括视频监控业务的切换频率和卡顿等)优化为目标,建立了基于视频内容处理低时延保障的问题;其次设计了基于凸优化的资源分配搜索方法对所提问题进行求解,最后对所提方案性能进行了仿真评估。
基金supported by the National Natural Science Foundation General Program of China under Grant No.61171110the National Basic Research Program of China under Grant No.2013CB329003
文摘Traditional cellular network requires that a user equipment(UE) should associate to the same base station(BS) in both the downlink(DL) and the uplink(UL). Based on dual connectivity(DC) introduced in LTE-Advanced R12, DL/UL decouple access scheme has been proposed, which is especially suitable for heterogeneous networks(Het Nets). This paper is the pioneer to take the DL/UL decouple access scheme into consideration and develop a novel resource allocation algorithm in a two-tier Het Net to improve the total system throughput in the UL and ease the load imbalance between macro base stations(MBSs) and pico base stations(PBSs). A model is formulated as a nonlinear integer programming, and the proposed algorithm is a sub-optimal algorithm based on the graph theory. First, an undirected and weighted interference graph is obtained. Next, the users are grouped to let users with large mutual interferences to be assigned to different clusters. Then, the users in different clusters are allocated to different resource blocks(RBs) by using the Hungarian algorithm. Simulation results show that the proposed algorithm can provide great promotions for both the total system throughput and the average cell edge user throughput and successfully ease the load imbalance between MBSs and PBSs.
基金supported by the NNSF of China(No.61177071, No.61250018)the Key Program of Shanghai Science and Technology Association (12dz1143000)
文摘In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.
