The experimental results of Benzyl Ntertbutyloxycarbonylβcyclohexylaspartate(Ⅰ)were reported in this paper.Starting from cheap and accessible Laspartic acid,the key intermediate of βcyclohexyl Ntertbutyloxycarbonyl...The experimental results of Benzyl Ntertbutyloxycarbonylβcyclohexylaspartate(Ⅰ)were reported in this paper.Starting from cheap and accessible Laspartic acid,the key intermediate of βcyclohexyl Ntertbutyloxycarbonylaspartate(Ⅱ)was prepared by esterification of aspartic acid via cyclohexanol catalyzed by sulfuric acid and further acylation via Boc2O.The synthesis of the title compound of(Ⅰ)was performed by benzylization of(Ⅱ)through benzyl bromide.The method is facile and the yield is higher than that in literatures.The structures of these compounds were verified by1H NMR and mp.,or by the corresponding authentic compounds.The discussion of the preparative conditions of Ⅰ and Ⅱ was also given.展开更多
从理论研究和仿真分析两方面对type III HARQ在无线信道环境下的性能进行了深入研究,并与其它两种HARQ方案的性能进行了分析对比。应用更新理论,得出了type I HARQ和type II HARQ 方案分别在AWGN和Rayleigh衰落信道下吞吐量的闭式解,对...从理论研究和仿真分析两方面对type III HARQ在无线信道环境下的性能进行了深入研究,并与其它两种HARQ方案的性能进行了分析对比。应用更新理论,得出了type I HARQ和type II HARQ 方案分别在AWGN和Rayleigh衰落信道下吞吐量的闭式解,对于type III HARQ虽无闭式的解,但给出了积分形式的解。此外,采用Turbo码为前向纠错码,对三种HARQ分别在AWGN和Rayleigh衰落信道条件下的吞吐量和残余FER等性能做了仿真。结果显示,对于任意的BF信道,包括AWGN信道,type III HARQ的性能总是比type II HARQ好,而type II HARQ总比type I HARQ好。而且,type III HARQ的优越性在Rayleigh衰落信道下更加突出。展开更多
Five years ago, ISTIC and IDG joined hands to bring out TelecomWorld - alocalized Chinese Technical Monthly Magazine dedicated to thegeneral readers both at home and abroad, featuring telecommunicationstechnologies, p...Five years ago, ISTIC and IDG joined hands to bring out TelecomWorld - alocalized Chinese Technical Monthly Magazine dedicated to thegeneral readers both at home and abroad, featuring telecommunicationstechnologies, products, services, markets and operations in the realm ofinformation industry with the aim to keep our readers abreast of the majorprogress and development trends in Information Technology and market.During the past 5 years, TW has seen the emergence of new telecommumcations technologies and services in the international arena and the fastdeployment of these technologies and services nationwide.The unprecedented success of Internet services in North America andEurope in the early 90s was soon followed by the fast growth of domesticIP networking since 5 years ago. Now, IP has become the driving force ofbroadband technology and market, arousing the interest of the domesticinformation industry in introducing state-of-the-art optical transport technology such as SDH, WDM, DWDM, and broadband switching technology such as ATM, as well as high-speed access technology such as FrameRelay xDSL, Gigabit router switch, etc. Besides IP data services, IP Phonehas just been rolled out in most of the major cities and shows sign of promise for the ISPs.On the mobile side, GSM is domnant in domestic market and willcontinue to grow by leaps and bounds, however, domestic market deregulation seems to be offering competitive opportunity for the latecomerCDMA to dip its finger in the pie.With full support from the government, the national information in-dustry has seen a rapid growth starting from the early 80s, when the Shang-hai Bell first introduced the advanced SPC switching technology fromabroad and started production and development domestica]ly, based onthe policy of "bartering markt for technology", which has been proven tobe very successful. This is followed by other national enterprises such asJulong Commnications Equipment Co., Datang Telecommunications Ltd.,Zhongxing Communications Co., Huawei Technology Ltd., etc. The market penetration of the national industry in the area of SPC switching equipments has exceeded 90%. Besides, the national optical communicationsindustry is catching up with the international level by independently developing 10Gbps SDH system following the successful development ofthe full range SDH system operating at 155Mbps-2.5Gbps.The fundamental reform in the information industry and the estab-lishment of new Ministry of lnformation Industry (MII) in place of theformer MPT and the emergence of China Unicom as the second telecomoperator in China will, no doubt, promote the migration of the fast growing domestic informati0n industry into sustalnable development in the nextmillenium.展开更多
文摘The experimental results of Benzyl Ntertbutyloxycarbonylβcyclohexylaspartate(Ⅰ)were reported in this paper.Starting from cheap and accessible Laspartic acid,the key intermediate of βcyclohexyl Ntertbutyloxycarbonylaspartate(Ⅱ)was prepared by esterification of aspartic acid via cyclohexanol catalyzed by sulfuric acid and further acylation via Boc2O.The synthesis of the title compound of(Ⅰ)was performed by benzylization of(Ⅱ)through benzyl bromide.The method is facile and the yield is higher than that in literatures.The structures of these compounds were verified by1H NMR and mp.,or by the corresponding authentic compounds.The discussion of the preparative conditions of Ⅰ and Ⅱ was also given.
文摘从理论研究和仿真分析两方面对type III HARQ在无线信道环境下的性能进行了深入研究,并与其它两种HARQ方案的性能进行了分析对比。应用更新理论,得出了type I HARQ和type II HARQ 方案分别在AWGN和Rayleigh衰落信道下吞吐量的闭式解,对于type III HARQ虽无闭式的解,但给出了积分形式的解。此外,采用Turbo码为前向纠错码,对三种HARQ分别在AWGN和Rayleigh衰落信道条件下的吞吐量和残余FER等性能做了仿真。结果显示,对于任意的BF信道,包括AWGN信道,type III HARQ的性能总是比type II HARQ好,而type II HARQ总比type I HARQ好。而且,type III HARQ的优越性在Rayleigh衰落信道下更加突出。
文摘Five years ago, ISTIC and IDG joined hands to bring out TelecomWorld - alocalized Chinese Technical Monthly Magazine dedicated to thegeneral readers both at home and abroad, featuring telecommunicationstechnologies, products, services, markets and operations in the realm ofinformation industry with the aim to keep our readers abreast of the majorprogress and development trends in Information Technology and market.During the past 5 years, TW has seen the emergence of new telecommumcations technologies and services in the international arena and the fastdeployment of these technologies and services nationwide.The unprecedented success of Internet services in North America andEurope in the early 90s was soon followed by the fast growth of domesticIP networking since 5 years ago. Now, IP has become the driving force ofbroadband technology and market, arousing the interest of the domesticinformation industry in introducing state-of-the-art optical transport technology such as SDH, WDM, DWDM, and broadband switching technology such as ATM, as well as high-speed access technology such as FrameRelay xDSL, Gigabit router switch, etc. Besides IP data services, IP Phonehas just been rolled out in most of the major cities and shows sign of promise for the ISPs.On the mobile side, GSM is domnant in domestic market and willcontinue to grow by leaps and bounds, however, domestic market deregulation seems to be offering competitive opportunity for the latecomerCDMA to dip its finger in the pie.With full support from the government, the national information in-dustry has seen a rapid growth starting from the early 80s, when the Shang-hai Bell first introduced the advanced SPC switching technology fromabroad and started production and development domestica]ly, based onthe policy of "bartering markt for technology", which has been proven tobe very successful. This is followed by other national enterprises such asJulong Commnications Equipment Co., Datang Telecommunications Ltd.,Zhongxing Communications Co., Huawei Technology Ltd., etc. The market penetration of the national industry in the area of SPC switching equipments has exceeded 90%. Besides, the national optical communicationsindustry is catching up with the international level by independently developing 10Gbps SDH system following the successful development ofthe full range SDH system operating at 155Mbps-2.5Gbps.The fundamental reform in the information industry and the estab-lishment of new Ministry of lnformation Industry (MII) in place of theformer MPT and the emergence of China Unicom as the second telecomoperator in China will, no doubt, promote the migration of the fast growing domestic informati0n industry into sustalnable development in the nextmillenium.
