Multi-hop relay is a significant topic in the wireless communication and it is provisioned in the 802.16j standards.At present,the major research on multi-hop relay is focused on the capacity,coverage,coordination,thr...Multi-hop relay is a significant topic in the wireless communication and it is provisioned in the 802.16j standards.At present,the major research on multi-hop relay is focused on the capacity,coverage,coordination,throughput,etc.But in this paper,a new concept about power-effective was discussed.Then,two power-effective coverage extension methods using two sectorized cellular approaches were introduced,i.e.,the widebeam three sector cell(WBTC) and the narrow-beam three sector cell(NBTC).Under such topologies,the consumption of power and optimal numbers of base stations(BSs) and relay stations(RSs) with respect to various user traffic densities were investigated.Finally,it is found that the performance of WBTC is better than NBTC.展开更多
In order to handle the huge amounts of data transmitted through hot spots and to increase cell coverage in buildings, this paper proposes a sectored cellular network with small cells (SCNSC) embedded in each sector. T...In order to handle the huge amounts of data transmitted through hot spots and to increase cell coverage in buildings, this paper proposes a sectored cellular network with small cells (SCNSC) embedded in each sector. Two region types, sectors and variable-radius small cells are classified in an SCNSC macro cell. Because the system capacity is enhanced by using fractional frequency reuse (FFR), the overall channel bandwidth is divided into two or three frequency bands depending on whether the number of sectors in a macro cell is even or odd. For the purpose of topological evaluation on the proposed SCNSC, we build an analytical model using Markov chain theory. The performance measures include new-call blocking and handoff-call dropping probabilities, average waiting times, and normalized throughputs in each sector and its embedded small cell by varying mobile stations’ moving speeds, the number of sectors, and the radius size of an embedded small cell. From the evaluation results, it is demonstrated that adjusting either the number of sectors or the coverage of an embedded cell can satisfy different service demands.展开更多
为增强浮式生产储油和卸油装置(Floating Production Storage And Offloading,FPSO)航行辅助系统设计的科学性和合理性,对航行辅助系统的结构、设计、设备选型、布置原则等进行介绍。在对相关规范分析和实船验证的基础之上,提出一套完整...为增强浮式生产储油和卸油装置(Floating Production Storage And Offloading,FPSO)航行辅助系统设计的科学性和合理性,对航行辅助系统的结构、设计、设备选型、布置原则等进行介绍。在对相关规范分析和实船验证的基础之上,提出一套完整的FPSO航行辅助系统设计方法。研究成果可为FPSO航行辅助系统的设计提供一定参考。展开更多
文摘Multi-hop relay is a significant topic in the wireless communication and it is provisioned in the 802.16j standards.At present,the major research on multi-hop relay is focused on the capacity,coverage,coordination,throughput,etc.But in this paper,a new concept about power-effective was discussed.Then,two power-effective coverage extension methods using two sectorized cellular approaches were introduced,i.e.,the widebeam three sector cell(WBTC) and the narrow-beam three sector cell(NBTC).Under such topologies,the consumption of power and optimal numbers of base stations(BSs) and relay stations(RSs) with respect to various user traffic densities were investigated.Finally,it is found that the performance of WBTC is better than NBTC.
文摘In order to handle the huge amounts of data transmitted through hot spots and to increase cell coverage in buildings, this paper proposes a sectored cellular network with small cells (SCNSC) embedded in each sector. Two region types, sectors and variable-radius small cells are classified in an SCNSC macro cell. Because the system capacity is enhanced by using fractional frequency reuse (FFR), the overall channel bandwidth is divided into two or three frequency bands depending on whether the number of sectors in a macro cell is even or odd. For the purpose of topological evaluation on the proposed SCNSC, we build an analytical model using Markov chain theory. The performance measures include new-call blocking and handoff-call dropping probabilities, average waiting times, and normalized throughputs in each sector and its embedded small cell by varying mobile stations’ moving speeds, the number of sectors, and the radius size of an embedded small cell. From the evaluation results, it is demonstrated that adjusting either the number of sectors or the coverage of an embedded cell can satisfy different service demands.
文摘为增强浮式生产储油和卸油装置(Floating Production Storage And Offloading,FPSO)航行辅助系统设计的科学性和合理性,对航行辅助系统的结构、设计、设备选型、布置原则等进行介绍。在对相关规范分析和实船验证的基础之上,提出一套完整的FPSO航行辅助系统设计方法。研究成果可为FPSO航行辅助系统的设计提供一定参考。
文摘2013年6月19日20:00至20日08:00,西北地区东部出现了罕见的暖区大暴雨,最大降水量达258 mm,小时最大降水量达65 mm,且伴随雷电天气。利用卫星、雷达、区域自动气象站、高空、地面观测资料和NCEP再分析资料,重点分析六盘山西南侧极端降水中尺度对流系统的发生发展及传播特征。结果表明:近似的喇叭口地形及六盘山的阻挡,使700 h Pa偏南风在六盘山的西南侧形成一支长约200~300 km的低空急流;低空急流激发对流云带发展、加强,大暴雨主要由对流云带中一个向前传播的β中尺度对流云团产生;雷达强回波中心高度低于4 km,低质心暖云降水特征明显,对流带中具有多单体结构,大于35 d BZ强回波单体呈南北带状分布,对流单体以每小时1次的频次沿低空急流自南向北移动,显著的"列车效应"形成了六盘山西南侧带状大暴雨区。
