Block-Orthogonal Frequency Division Multiplexing in Multi-Path Fading Channel

Orthogonal frequency division multiplexing (OFDM) is robust against multi-path interference due to using a lot of low symbol rate sub-carriers. In order to mitigate the degradation due to multi-path interference, guard time interval (GI) is inserted into each OFDM symbol. However, redundant allocation to GI leads to loss of effective transmission power. We propose the Block-OFDM which can reduce the GI overhead ratio per frame compared with conventional OFDM. In Block-OFDM system frequency domain equalization (FDE) is carried out in order to remove multi-path interference. We evaluated Block-OFDM performance in a frequency selective fading channel and compared with that of conventional OFDM. Ryohei Kimura received his B.E. and M.S degrees in communications engineering form Tohoku University, Sendai, Japan, in 2001 and 2003, respectively. In 2003, he joined Panasonic Mobile Communications Co., Ltd. His current research interests include such mobile communication technologies as OFDM and MIMO (MLD), and the like. Akiyoshi Monma received his B.E. in communications engineering form Tohoku University, Sendai, Japan, in 1998. In 1998, he joined Panasonic Mobile Communications Sendai R&D Lab. Co., Ltd. His current research interests include such mobile communication technologies as OFDM and PAPR reduction, and the like. Jinsong Duan received his B.E. and M.S. from Changsha Institute of Technology, China in 1987 and 1990. He received his Ph.D. from Osaka City University, Japan in 2000. From 2000–2003 he was with Mitsubishi Electric Corporation, where he engaged in research and development of WCDMA systems. From 2003, he joined Panasonic Mobile Communications Co., Ltd. His current interests include such mobile communication technologies as OFDM, MIMO, link adaptation, scheduling, and TDMA/FDMA/CDMA systems. Mitsuru Uesugi received his B.E. degree from Waseda University in 1986 and received his Ph.D degree from Tohoku University in 2004, respectively. He is a general manager in the Mobile Communication Technology Development Center of Panasonic Mobile Communications Co., Ltd. His current research interests include such mobile communication technologies as equalization, interference cancellation, modulation method, and the like.     

FlexE技术及其在5G承载网中的应用探析

5G对承载网络的带宽、时延、切片、可靠性等方面提出了更高的要求。FlexE技术重用现有IEEE 802.3以太网物理层标准,在MAC层与PCS层中新增Flex Shim层,实现网络灵活性、多速率、刚性接口等特性。其捆绑、通道化、子速率等功能,可以与IP/Ethernet技术良好对接,大力助推5G承载网络的发展,为5G技术的应用提供保障。随着5G产业的不断发展与完善,FlexE技术必将得到广泛的应用。     

RTCWeb及其与IMS的融合研究

RTCWeb是一种实现免插件Web客户端及通信的技术。相比传统应用客户端,RTCWeb客户端操作更加便捷,开发更加灵活,并且能脱离操作系统和平台的限制,其对于业务开发者、网络运营商和终端用户都是一种更好的选择。本文首先对RTCWeb通信模型及关键技术进行了介绍;然后针对RTCWeb和IMS融合提出了构想并给出此构想下的具体解决方案;最后展望了基于IMS的RTCWeb系统的未来演进趋势。     

半绝缘InP中深能级缺陷对电学性质的影响和缺陷的控制

综合深能级缺陷和电学性质的测试结果,证明了半绝缘InP单晶材料的电学性能、热稳定性、均匀性等性能与材料中一些深能级缺陷的含量密切相关.通过分析深能级缺陷产生的规律与热处理及生长条件的关系,给出了抑制缺陷产生,提高材料质量的途径.对缺陷的属性与形成机理进行了分析讨论.     

基于类渗流导电的超薄栅氧化层软击穿后的电流模拟

研究了超薄栅氧化层(≤3.0nm)软击穿(soft breakdown,SBD)后的栅电流和衬底电流特性.提出了一个基于类渗流导电的SBD后栅电流和衬底电流的解析公式--类渗流导电公式.该公式能够在较大的电压范围(-4～+3V)模拟氧化层SBD后的栅电流和衬底电流的电流-电压特性,为超薄栅氧化层可靠性的研究提供了一个较为简便的公式.     

电信BS架构系统迁移及云化研究

深入分析了电信BS架构系统迁移的相关问题及解决方案,并对BS架构系统IaaS及PaaS云化方案进行了研究,提出了两种IaaS和一种PaaS解决方案,能有效地解决电信BS架构系统Web及应用层云化相关问题,同时给出了迁移及云化演进路径和分阶段推进建议,对于推进云计算在IT支撑系统中的应用,具有较好的价值贡献。     

山西广播电视监测网络技术

根据SDH通信原理,研究并拓展了基于数字微波传输通道的以太网络技术,以山西广播电视监测网络为实例,详细阐述了网络建设过程中的关键技术和维护要点。该网络结合自身特点,因地制宜采用数字微波传输方式成功进行组网,不仅合理利用了广电资源,在数字微波的综合应用方面也有较为实用的借鉴意义。     

High‐Strength Laminated Copper Matrix Nanocomposites Developed from a Single‐Walled Carbon Nanotube Film with Continuous Reticulate Architecture

A critical challenge in nanocomposite fabrication by adding SWCNTs as reinforcement is to realize an effective transfer of the excellent mechanical properties of the SWCNTs to the macroscale mechanical properties of the matrix. Using directly grown SWCNT films with continuous reticulate structure as the template, Cu/SWCNTs/Cu laminated nanocomposites are fabricated by an electrodepositing process. The resulting Cu/SWCNTs/Cu laminated nanocomposites exhibit extremely high strength and Young's modulus. The estimated Young's modulus of the SWCNT bundles in the composite are between 860 and 960 GPa. Such a high strength and an effective load‐transfer capacity are ascribed to the unique continuous reticulate architecture of SWCNT films and the strong interfacial strength between the SWCNTs and Cu matrix. Raman spectroscopy is used to characterize the loading status of the SWCNTs in the strained composite. It provides a route to investigate the load transfer of SWCNTs in the metal matrix composites.     

约束层材料及靶材表面特征对激光冲击波的影响

观测了不同约束层材料及不同靶材表面特征情况下产生的激光冲击波。实验发现 ,约束层对激光冲击波的脉宽有显著的展宽作用 ,且冲击波的峰压值随约束层材料的声阻抗的增大而增大。另外 ,研究了表面涂层对冲击结果的影响 ,重新认识了其作用。针对于实际应用 ,还试验了曲面靶材的冲击强化 ,讨论了约束结构的有效性问题。     

^（60）Co γ-rays irradiation effect in DC performance of AlGaN/GaN high electron mobility transistors

Unpassivated/passivated AlGaN/GaN high electron mobility transistors （HEMTs） were exposed to 1.25 MeV 60Co γ-rays at a dose of 1 Mrad（Si）. The saturation drain current of the unpassivated devices decreased by 15% at 1 Mrad γ-dose, and the maximal transconductance decreased by 9.1% under the same condition; more- over, either forward or reverse gate bias current was significantly increased, while the threshold voltage is relatively unaffected. By sharp contrast, the passivated devices showed scarcely any change in saturation drain current and maximal transconductance at the same γ dose. Based on the differences between the passivated HEMTs and un- passivated HEMTs, adding the C–V measurement results, the obviously parameter degradation of the unpassivated AlGaN/GaN HEMTs is believed to be caused by the creation of electronegative surface state charges in sourcegate spacer and gate–drain spacer at the low dose （1 Mrad）. These results reveal that the passivation is effective in reducing the effects of surface state charges induced by the 60Co γ-rays irradiation, so the passivation is an effective reinforced approach.