The IEEE 802.15.4 standard provides Guaranteed Time Slot (GTS) mechanism for reliable transmission. GTS mechanism is suitable for transmitting time-sensitive data because it allocates time slots to a specific node. However, the GTS mechanism in the standard can be used only for one-hop communication. This paper proposes and implements a multihop GTS mechanism for reliable transmission in multihop networks. Simulation results using NS-2 show that low delay and high delivery ratio can be achieved using the proposed mechanism.

Much active research has been done on service science in order to improve productivity, efficiency and customer satisfaction of IT service. If any software application or module in IT service behaves incorrectly, service quality and customer satisfaction will decrease significantly. In order to solve such problems, research on software assurance has been drawn much attention recently. Most widely recognized research has been carried out by various government agencies and research institutes such as DHS, DoD, NIST, NASA, SAFECode, CWE TM , and SANS. This paper investigates various research on software assurance and discusses the unconsidered matters that have not been studied or solved yet. Finally, a system for the improved software assurance is proposed.

No abstract

No abstract

No abstract