Protocols for key management are compared and evaluated from the point of view on mobile ad hoc networks (MANET). The issues of fault-tolerance and efficiency of key distribution protocols for group communications in MANET are addressed. Most key distribution protocols existing today are primarily designed for wire-line networks. These protocols either fail to work as intended or cannot work at all when they are applied to the demanding environment of MANET. Parameters and performance of different protocols are analyzed, and then a flat is given out, on which new protocols or existing ones are designed and modified, so that they can be robust, scalable and efficient in MANET.
The AgTCNQ thin-film was prepared by vacuum vapor co-deposition and characterized by infrared spectral analysis,and then a uniform AgTCNQ （TCNQ-- 7,7,8,8-tetracyanoquinodimethane） thin-film layer was sandwiched in a Ti/AgTCNQ/Ati crossbar structure array as organic bistable devices （OBD）.A reversible and reproducible memory switching property,caused by intermolecular charge transfer （CT） in the AgTCNQ thin-film, was observed in the organic bista- ble devices. The positive threshold voltage from the high impedance state to the low impedance was about 3.8-5V, with the reverse phenomenon occurring at a negative voltage of - 3.5- - 4. 4V,lower than that with a CuTCNQ active layer. The crossbar array of OBDs with AgTCNQ is promising for nonvolatile organic memory applications.
A one-time programmable metal-molecule-metal device, with a modified Rotaxane LB film as the functional layer, is proposed for potential use in organic programmable and fault tolerant circuits like inorganic anti-fuse devices used in field programmable gate arrays. All fabrication methods involved are low temperature processes, ensuring that this device can be integrated with other organic devices. Electrical measurements show that this device has a good one-time programming capability. Its break down voltage is 2.2V, off-state resistance is 15kΩ, and on-state resistance is 54Ω These characteristics come from the penetration of metal atoms into molecular film under high electronic field.
