In Multi-user MIMO (MU-MIMO) downlink system, suitable user selection schemes can improve spatial diversity gain. In most of previous studies, it is always assumed that the base station (BS) knows full channel state i...In Multi-user MIMO (MU-MIMO) downlink system, suitable user selection schemes can improve spatial diversity gain. In most of previous studies, it is always assumed that the base station (BS) knows full channel state information (CSI) of each user, which does not consider the reality. However, there are only limited feedback bits in real system. Besides, user fairness is often ignored in most of current user selection schemes. To discuss the user fairness and limited feedback, in this paper, the user selection scheme with limited feedback bits is proposed. The BS utilizes codebook precoding transmitting strategy with LTE codebook. Furthermore, this paper analyzes the influence of the number of feedback bits and the number of users on user fairness and system sum capacity. Simulation results show that in order to achieve better user fairness, we can use fewer bits for feedback CSI when the number of user is small, and more feedback bits when the number of users is large.展开更多
Non-orthogonal multiple access(NOMA)is one of the key 5G technology which can improve spectrum efficiency and increase the number of user connections by utilizing the resources in a non-orthogonal manner.NOMA allows m...Non-orthogonal multiple access(NOMA)is one of the key 5G technology which can improve spectrum efficiency and increase the number of user connections by utilizing the resources in a non-orthogonal manner.NOMA allows multiple terminals to share the same resource unit at the same time.The receiver usually needs to configure successive interference cancellation(SIC).The receiver eliminates co-channel interference(CCI)between users and it can significantly improve the system throughput.In order to meet the demands of users and improve fairness among them,this paper proposes a new power allocation scheme.The objective is to maximize user fairness by deploying the least fairness in multiplexed users.However,the objective function obtained is non-convex which is converted into convex form by utilizing the optimal Karush-Kuhn-Tucker(KKT)constraints.Simulation results show that the proposed power allocation scheme gives better performance than the existing schemes which indicates the effectiveness of the proposed scheme.展开更多
Based on the proportionally fair scheme that Kelly proposed to solve the optimization problems for utility function in networks, and in order to improve the congestion control performance for the queue in router, the ...Based on the proportionally fair scheme that Kelly proposed to solve the optimization problems for utility function in networks, and in order to improve the congestion control performance for the queue in router, the linear and terminal sliding active queue management (AQM) algorithms are designed. Especially in the ter-minal sliding AQM algorithm, a special nonlinear terminal sliding surface is designed in order to force queue length to reach the desired value in finite time. The upper bound of the time is also obtained. Simulation re-sults demonstrate that the proposed congestion algorithm enables the system be better transient and stable performance. At the same time, the robustness is guaranteed.展开更多
It is common for teachers to use others'copyrighted works for the purpose of teaching.The current copyright law in many nations only exempts educational use in the context of offline classroom teaching.The use of ...It is common for teachers to use others'copyrighted works for the purpose of teaching.The current copyright law in many nations only exempts educational use in the context of offline classroom teaching.The use of others’copyrighted material in online teaching may still constitute copyright infringement.To protect teachers from the chilling effect of copyright infringement,to safeguard the public's freedom to obtain knowledge,and to ensure the commensurability of the profits and responsibilities of online teaching platforms,this paper proposes a levy scheme for online teaching.Under the levy scheme,teachers are free to use others’published work for the purpose of online teaching,provided that such use does not conflict with a normal exploitation of the work and does not unreasonably prejudice the legitimate interest of the copyright owner.Online teaching platforms should remunerate the copyright owner of the work used in the platform according to the number of participants of the course that uses such work.展开更多
针对传统可证明数据持有(Provable Data Possession,PDP)方案中要求客户端是诚实的这一问题,基于区块链技术提出了公平的可证明数据持有方案.在传统PDP方案中,总是假定服务器是半诚实而客户端是可信的,这对服务器而言是不公平的.在基于...针对传统可证明数据持有(Provable Data Possession,PDP)方案中要求客户端是诚实的这一问题,基于区块链技术提出了公平的可证明数据持有方案.在传统PDP方案中,总是假定服务器是半诚实而客户端是可信的,这对服务器而言是不公平的.在基于区块链的公平PDP方案中,用于检验的元数据不再由客户端生成,而是由区块链节点生成并对其达成共识.因此,借助区块链的分布式信任性质可以实现PDP方案的互信机制,保证客户端和云服务器之间的公平性.同时,利用哈希函数、Pedersen承诺实现高效的公平PDP方案.分析所提方案的安全性、计算开销、通信开销以及冗余率.分析结果表明,在保障安全性的基础上,所提方案比同类方案具有更优的计算开销、通信开销及冗余率.展开更多
文摘In Multi-user MIMO (MU-MIMO) downlink system, suitable user selection schemes can improve spatial diversity gain. In most of previous studies, it is always assumed that the base station (BS) knows full channel state information (CSI) of each user, which does not consider the reality. However, there are only limited feedback bits in real system. Besides, user fairness is often ignored in most of current user selection schemes. To discuss the user fairness and limited feedback, in this paper, the user selection scheme with limited feedback bits is proposed. The BS utilizes codebook precoding transmitting strategy with LTE codebook. Furthermore, this paper analyzes the influence of the number of feedback bits and the number of users on user fairness and system sum capacity. Simulation results show that in order to achieve better user fairness, we can use fewer bits for feedback CSI when the number of user is small, and more feedback bits when the number of users is large.
文摘Non-orthogonal multiple access(NOMA)is one of the key 5G technology which can improve spectrum efficiency and increase the number of user connections by utilizing the resources in a non-orthogonal manner.NOMA allows multiple terminals to share the same resource unit at the same time.The receiver usually needs to configure successive interference cancellation(SIC).The receiver eliminates co-channel interference(CCI)between users and it can significantly improve the system throughput.In order to meet the demands of users and improve fairness among them,this paper proposes a new power allocation scheme.The objective is to maximize user fairness by deploying the least fairness in multiplexed users.However,the objective function obtained is non-convex which is converted into convex form by utilizing the optimal Karush-Kuhn-Tucker(KKT)constraints.Simulation results show that the proposed power allocation scheme gives better performance than the existing schemes which indicates the effectiveness of the proposed scheme.
文摘Based on the proportionally fair scheme that Kelly proposed to solve the optimization problems for utility function in networks, and in order to improve the congestion control performance for the queue in router, the linear and terminal sliding active queue management (AQM) algorithms are designed. Especially in the ter-minal sliding AQM algorithm, a special nonlinear terminal sliding surface is designed in order to force queue length to reach the desired value in finite time. The upper bound of the time is also obtained. Simulation re-sults demonstrate that the proposed congestion algorithm enables the system be better transient and stable performance. At the same time, the robustness is guaranteed.
基金This work was supported by Guangdong Planning Office of Philosophy and Social Sciences 2020(project no.GD20YFX05).
文摘It is common for teachers to use others'copyrighted works for the purpose of teaching.The current copyright law in many nations only exempts educational use in the context of offline classroom teaching.The use of others’copyrighted material in online teaching may still constitute copyright infringement.To protect teachers from the chilling effect of copyright infringement,to safeguard the public's freedom to obtain knowledge,and to ensure the commensurability of the profits and responsibilities of online teaching platforms,this paper proposes a levy scheme for online teaching.Under the levy scheme,teachers are free to use others’published work for the purpose of online teaching,provided that such use does not conflict with a normal exploitation of the work and does not unreasonably prejudice the legitimate interest of the copyright owner.Online teaching platforms should remunerate the copyright owner of the work used in the platform according to the number of participants of the course that uses such work.
文摘提出根据各尾号小汽车空间分布特征计算尾号出行OD矩阵的方法,基于公平性原则,构建尾号限行方案优化模型.上层模型以工作日(周一~周五)车辆总走行时间最小为目标,以各工作日每辆小汽车早高峰平均走行时间基本相同且每周各尾号限行次数不大于1为约束,给出限号方案;下层模型基于用户均衡原则分配OD交通量.限号方案与分配结果相互作用,达到均衡状态时可得最优限号组合方案.为验证模型,以D市为例进行实证研究,结果表明,与基于经验的限号方案相比,优化方案下路网通行效率可提高5.35%,工作日车辆总走行时间降低0.894×105h,日均单车走行时间减少4.5 min.
文摘针对传统可证明数据持有(Provable Data Possession,PDP)方案中要求客户端是诚实的这一问题,基于区块链技术提出了公平的可证明数据持有方案.在传统PDP方案中,总是假定服务器是半诚实而客户端是可信的,这对服务器而言是不公平的.在基于区块链的公平PDP方案中,用于检验的元数据不再由客户端生成,而是由区块链节点生成并对其达成共识.因此,借助区块链的分布式信任性质可以实现PDP方案的互信机制,保证客户端和云服务器之间的公平性.同时,利用哈希函数、Pedersen承诺实现高效的公平PDP方案.分析所提方案的安全性、计算开销、通信开销以及冗余率.分析结果表明,在保障安全性的基础上,所提方案比同类方案具有更优的计算开销、通信开销及冗余率.
