The ZigBee as the main supporting technology for the wireless sensor network has received extensive attention. Completed ZigBee protocol kits consist of the high-level application specification, the application conver...The ZigBee as the main supporting technology for the wireless sensor network has received extensive attention. Completed ZigBee protocol kits consist of the high-level application specification, the application convergence layer, the network layer, the data link layer, and the Physical (PHY) layer. The protocols of the network layer and higher ones are set up by the ZigBee Alliance, the physical layer and the Media Access Control (MAC) layer are defined by the IEEE 802.15.4 standard. The IEEE 802.15.4 physical layer simply adopts technologies of mapping from bit to symbol, conversion from symbol to chip sequence, and Offset Quadrature Phase Shift Keying (OQPSK) modulation, avoiding complicated arithmetic such as channel coding. The IEEE 802.15.4 MAC layer adopts Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) technology and supports the sleeping mode. The ZigBee enables low data transmission rate, low power consumption at low cost, and is more suitable for industry monitoring systems, sensor networks, home monitoring systems, and security systems.展开更多
Data centers are crucial elements in modern information technology.In order to implement the next generation of data centers,new challenges must be overcome.These include reducing the energy consumption,increasing the...Data centers are crucial elements in modern information technology.In order to implement the next generation of data centers,new challenges must be overcome.These include reducing the energy consumption,increasing the data rates,reducing the communication latency,increasing the flexibility and scalability,and reducing the maintenance time and cost.One promising way for meeting these challenges is to employ multichannel optical wireless communication as part of the data center hybrid communication network.In this paper,we analyze three technologies that could be used in this context:MIMO(Multiple-in-Multipleout),multiplexing through orbital angular momentum of light,and direct modulation through the large number of modes associated with orbital angular momentum.Our results indicate that these technologies could provide an innovative and flexible means of meeting the challenges of the next generation of data centers.展开更多
文摘The ZigBee as the main supporting technology for the wireless sensor network has received extensive attention. Completed ZigBee protocol kits consist of the high-level application specification, the application convergence layer, the network layer, the data link layer, and the Physical (PHY) layer. The protocols of the network layer and higher ones are set up by the ZigBee Alliance, the physical layer and the Media Access Control (MAC) layer are defined by the IEEE 802.15.4 standard. The IEEE 802.15.4 physical layer simply adopts technologies of mapping from bit to symbol, conversion from symbol to chip sequence, and Offset Quadrature Phase Shift Keying (OQPSK) modulation, avoiding complicated arithmetic such as channel coding. The IEEE 802.15.4 MAC layer adopts Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) technology and supports the sleeping mode. The ZigBee enables low data transmission rate, low power consumption at low cost, and is more suitable for industry monitoring systems, sensor networks, home monitoring systems, and security systems.
文摘Data centers are crucial elements in modern information technology.In order to implement the next generation of data centers,new challenges must be overcome.These include reducing the energy consumption,increasing the data rates,reducing the communication latency,increasing the flexibility and scalability,and reducing the maintenance time and cost.One promising way for meeting these challenges is to employ multichannel optical wireless communication as part of the data center hybrid communication network.In this paper,we analyze three technologies that could be used in this context:MIMO(Multiple-in-Multipleout),multiplexing through orbital angular momentum of light,and direct modulation through the large number of modes associated with orbital angular momentum.Our results indicate that these technologies could provide an innovative and flexible means of meeting the challenges of the next generation of data centers.
