We investigate the bandwidth allocation and power control schemes in orthogonal frequency division multiplexing (OFDM) based multi-hop cognitive radio networks,and the color-sensitive graph coloring (CSGC) model is vi...We investigate the bandwidth allocation and power control schemes in orthogonal frequency division multiplexing (OFDM) based multi-hop cognitive radio networks,and the color-sensitive graph coloring (CSGC) model is viewed as an efficient solution to the spectrum assignment problem. We extend the model by taking into account the power control strategy to avoid interference among secondary users and adapt dynamic topology. We formulate the optimization problem encompassing the channel allocation,power control with the interference constrained below a tolerable limit. The optimization objective with two different optimization strategies focuses on the routes rather than the links as in traditional approaches. A heuristic solution to this nondeterministic polynomial (NP)-hard problem is presented,which performs iterative channel allocation according to the lowest transmission power that guarantees the link connection and makes channel reuse as much as possible,and then the transmission power of each link is maximized to improve the channel capacity by gradually adding power level from the lowest transmission power until all co-channel links cannot satisfy the interference constraints. Numerical results show that our proposed strategies outperform the existing spectrum assignment algorithms in the performance of both the total network bandwidth and minimum route bandwidth of all routes,meanwhile,saving the transmission power.展开更多
探讨软件定义网络(Software Defined Network,SDN)技术在广播电视播控网络智能化改造中的应用。分析智能化改造的业务、技术和经济需求,指出传统网络架构在面临媒体形态多样化和观众需求个性化时的局限性。阐述SDN技术在网络架构优化、...探讨软件定义网络(Software Defined Network,SDN)技术在广播电视播控网络智能化改造中的应用。分析智能化改造的业务、技术和经济需求,指出传统网络架构在面临媒体形态多样化和观众需求个性化时的局限性。阐述SDN技术在网络架构优化、动态资源分配、流量工程优化、安全保障强化以及开放接口与生态系统构建等方面的应用策略。通过引入SDN技术,广播电视播控网络能够实现更高效、灵活和安全的运行,满足不断增长的业务需求,降低运营成本,推动行业的数字化转型和升级。展开更多
The key technologies involved in the evolution of the Cloud-based Radio Access Network(C-RAN) are discussed in this paper. Taking the Frameless Network Architecture(FNA) as a starting point, a cell-lessbased network t...The key technologies involved in the evolution of the Cloud-based Radio Access Network(C-RAN) are discussed in this paper. Taking the Frameless Network Architecture(FNA) as a starting point, a cell-lessbased network topology for a multi-tier Heterogeneous Network(Het Net) and ultra-dense network is proposed. The FNA network topology modeling is researched with centralized processing and distributed antenna deployments. The Antenna Element(AE) is released as a new dimensional radio resource that is included in the centralized Radio Resource Management(RRM) processes. This contributes to the on-demand user-centric serving-set associations with cell-edge effect elimination. The Control Plane(CP) and User Plane(UP) separation and adaptation are introduced for energy efficiency improvements. The centralized RRM and different optimization goals are discussed for fully exploring the merits from the centralized computing of C-RAN. Considering the complexity, near-optimal approaches for specific users' Quality-of-Service(Qo S) requirements are addressed. Finally, based on the research highlighted above, the way forward of C-RAN evolution is discussed.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 60496315, 60702039, and 60802009)the National High-Tech Research and Development Program (863) of China (Nos. 2006AA0Z277 and 2008AA01Z211)+1 种基金the International Science and Technology Cooperation Programme of China (No. 2008DFA11630)the Natural Science Foundation of Hubei Province, China (No. 2008CDB325)
文摘We investigate the bandwidth allocation and power control schemes in orthogonal frequency division multiplexing (OFDM) based multi-hop cognitive radio networks,and the color-sensitive graph coloring (CSGC) model is viewed as an efficient solution to the spectrum assignment problem. We extend the model by taking into account the power control strategy to avoid interference among secondary users and adapt dynamic topology. We formulate the optimization problem encompassing the channel allocation,power control with the interference constrained below a tolerable limit. The optimization objective with two different optimization strategies focuses on the routes rather than the links as in traditional approaches. A heuristic solution to this nondeterministic polynomial (NP)-hard problem is presented,which performs iterative channel allocation according to the lowest transmission power that guarantees the link connection and makes channel reuse as much as possible,and then the transmission power of each link is maximized to improve the channel capacity by gradually adding power level from the lowest transmission power until all co-channel links cannot satisfy the interference constraints. Numerical results show that our proposed strategies outperform the existing spectrum assignment algorithms in the performance of both the total network bandwidth and minimum route bandwidth of all routes,meanwhile,saving the transmission power.
文摘探讨软件定义网络(Software Defined Network,SDN)技术在广播电视播控网络智能化改造中的应用。分析智能化改造的业务、技术和经济需求,指出传统网络架构在面临媒体形态多样化和观众需求个性化时的局限性。阐述SDN技术在网络架构优化、动态资源分配、流量工程优化、安全保障强化以及开放接口与生态系统构建等方面的应用策略。通过引入SDN技术,广播电视播控网络能够实现更高效、灵活和安全的运行,满足不断增长的业务需求,降低运营成本,推动行业的数字化转型和升级。
基金supported by the National High Technology Research and Development Program of China No.2014AA01A701Nature and Science Foundation of China under Grants No.61471068,61421061+2 种基金Beijing Nova Programme No.Z131101000413030International Collaboration Project No.2015DFT10160National Major Project No.2016ZX03001009-003
文摘The key technologies involved in the evolution of the Cloud-based Radio Access Network(C-RAN) are discussed in this paper. Taking the Frameless Network Architecture(FNA) as a starting point, a cell-lessbased network topology for a multi-tier Heterogeneous Network(Het Net) and ultra-dense network is proposed. The FNA network topology modeling is researched with centralized processing and distributed antenna deployments. The Antenna Element(AE) is released as a new dimensional radio resource that is included in the centralized Radio Resource Management(RRM) processes. This contributes to the on-demand user-centric serving-set associations with cell-edge effect elimination. The Control Plane(CP) and User Plane(UP) separation and adaptation are introduced for energy efficiency improvements. The centralized RRM and different optimization goals are discussed for fully exploring the merits from the centralized computing of C-RAN. Considering the complexity, near-optimal approaches for specific users' Quality-of-Service(Qo S) requirements are addressed. Finally, based on the research highlighted above, the way forward of C-RAN evolution is discussed.
