Compared with the services in 3G, services in Beyond 3G (B3G) have some distinctive characteristics such as the packet data services being the majority, more service types, larger scale of services, higher peak transm...Compared with the services in 3G, services in Beyond 3G (B3G) have some distinctive characteristics such as the packet data services being the majority, more service types, larger scale of services, higher peak transmission rate, enlarged range of transmission rates, more spatial and temporal distribution differences, and more service transmission requests occurring in fast moving vehicles. In order to meet the requirements of B3G services, the B3G systems must have great improvement in network architecture, air interface scheme, radio resource allocation strategy, frequency bands, and Radio Frequency (RF) technology etc. Therefore, the research of the B3G systems should focus on the theory of generalized cellular communications networks, theory of the Multiple Input Multiple Output (MIMO) wireless transmission system, matching of radio resources to new-type air interfaces, new iterative detection and adaptive link methods, and new-type antenna and RF technologies.展开更多
This paper applies the perspective of business ecosystem to mobile communications industry,trying to help mobile network operators improve their strategies in the era of the third generation mobile communications(3G)....This paper applies the perspective of business ecosystem to mobile communications industry,trying to help mobile network operators improve their strategies in the era of the third generation mobile communications(3G).According to the definition of the business ecosystem,the ecosystem structure of mobile network operators is analyzed.As an important hub in the ecosystem,mobile network operators are advised to take a keystone strategy.The key points of the strategy are summarized.Finally,suggestions for Chinese mobile network operators are given based on the analysis.展开更多
Holistic tin-plating on the outer conductor is one of the key processes in the manufacture of semi-flexible coaxial cable, which is widely applied to the third generation (3G) mobile communication system. However, in ...Holistic tin-plating on the outer conductor is one of the key processes in the manufacture of semi-flexible coaxial cable, which is widely applied to the third generation (3G) mobile communication system. However, in the traditional horizontal tin-plating process, disadvantages such as the pinhole defects and low productivity effect cannot be avoided. In this paper, a vertical tin-plating process was proposed to reduce the pinhole defects and improve the tincoating quality. Compared with the traditional horizontal tin-plating process, the immersion length was reduced from 300-400 mm to 10-100 mm and the tin-plating time was reduced from 7 s to 3 s in the proposed method. The experimental results indicate that immersion length and time are key parameters for the tin-plating quality. With this new tin-plating process, the experimental results show that the pinhole defects can be eliminated effectively by controlling the immersion depth below 100 mm and tin-plating time at 3 s. The thickness of tin-coating increased from not more than 5 μm to 12.3 μm with the proposed vertical tin-plating process. Meanwhile, the thickness of the intermetallic compounds (IMCs) layer between the tin-coating and copper wires was reduced from 3.26 μm to 0.62 μm if the immersion time decreased from 30 s to 1 s. Besides, a self-developed flux, which possesses a boiling point or decomposed temperature of active components over 300℃, exhibits a better efficiency in reducing the pinhole formation.展开更多
基金Program ofNational Nature Science Foundation of China(No. 60496311) Project of National "863"Plan ofChina (No. 2005AA121052)
文摘Compared with the services in 3G, services in Beyond 3G (B3G) have some distinctive characteristics such as the packet data services being the majority, more service types, larger scale of services, higher peak transmission rate, enlarged range of transmission rates, more spatial and temporal distribution differences, and more service transmission requests occurring in fast moving vehicles. In order to meet the requirements of B3G services, the B3G systems must have great improvement in network architecture, air interface scheme, radio resource allocation strategy, frequency bands, and Radio Frequency (RF) technology etc. Therefore, the research of the B3G systems should focus on the theory of generalized cellular communications networks, theory of the Multiple Input Multiple Output (MIMO) wireless transmission system, matching of radio resources to new-type air interfaces, new iterative detection and adaptive link methods, and new-type antenna and RF technologies.
文摘This paper applies the perspective of business ecosystem to mobile communications industry,trying to help mobile network operators improve their strategies in the era of the third generation mobile communications(3G).According to the definition of the business ecosystem,the ecosystem structure of mobile network operators is analyzed.As an important hub in the ecosystem,mobile network operators are advised to take a keystone strategy.The key points of the strategy are summarized.Finally,suggestions for Chinese mobile network operators are given based on the analysis.
基金Supported by Science and Technology Support Project of Tianjin Science and Technology Commission (No.10ZCKFGX3500)
文摘Holistic tin-plating on the outer conductor is one of the key processes in the manufacture of semi-flexible coaxial cable, which is widely applied to the third generation (3G) mobile communication system. However, in the traditional horizontal tin-plating process, disadvantages such as the pinhole defects and low productivity effect cannot be avoided. In this paper, a vertical tin-plating process was proposed to reduce the pinhole defects and improve the tincoating quality. Compared with the traditional horizontal tin-plating process, the immersion length was reduced from 300-400 mm to 10-100 mm and the tin-plating time was reduced from 7 s to 3 s in the proposed method. The experimental results indicate that immersion length and time are key parameters for the tin-plating quality. With this new tin-plating process, the experimental results show that the pinhole defects can be eliminated effectively by controlling the immersion depth below 100 mm and tin-plating time at 3 s. The thickness of tin-coating increased from not more than 5 μm to 12.3 μm with the proposed vertical tin-plating process. Meanwhile, the thickness of the intermetallic compounds (IMCs) layer between the tin-coating and copper wires was reduced from 3.26 μm to 0.62 μm if the immersion time decreased from 30 s to 1 s. Besides, a self-developed flux, which possesses a boiling point or decomposed temperature of active components over 300℃, exhibits a better efficiency in reducing the pinhole formation.
