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Cognitive Radio (CR) is a key technology for improving the utilization level of the overall radio spectrum in wireless communications. It is able to sense and change its transmission and reception parameters adaptively according to spectrum availability in different spectrum channels. The Cognition Cycle (CC) is a state machine that is embodied in each CR host that defines the mechanisms related to...
Next generation wireless networks will be heterogeneous, where several primary users (PU e.g. licensed users) and secondary users (SU e.g. unlicensed users) can operate in the same dynamic and reconfigurable networks at a given time. The major challenge in this heterogeneous radio environment is to enable the coexistence between PU and SU which will further improve the efficient use of radio spectrum...
In cognitive radio networks, secondary users conduct local sensing to use underutilized spectrum bands. However, every secondary user's local sensing usually gives rise to much sensing overhead. Moreover, a globally synchronized quiet period cannot be determined in a decentralized network. In this paper, we propose a zone-based distributed sensing scheme, in which multiple secondary users alternate...
Cognitive wireless network consisted of multiple different types of wireless interface is one of efficient wireless transmission methods for Disaster Information Network, because it solves single wireless network problems like characteristics of wireless frequency or congestion form the use of same radio frequency. However, even if Disaster Information Network consisted of Cognitive Wireless Network,...
In this paper, we propose a dynamic route construction method based on measured characteristics of radio propagation in a real environment. Our method first measures characteristics of radio propagation for each link, and determines a communication route from every node to the sink node and its transmission power based on the measured characteristics. While operating the system, our method dynamically...
This paper presents a new routing protocol named RACE (network conditions Aware geographical forwarding protocol for real-time applications in mobile wireless sensor networks) that was developed to address the challenges found while using WSNs in a running competition scenario: QoS, mobility, and high workload. RACE aims to provide QoS requirements to the application layer by giving priority to real-time...
Triage is a emergency life-saving process to prioritize patients based on severity of their condition in disasters. Triage has been introduced to medical treatment scenes in recent years. In Triage, patients are classified into 4 groups according to their priority based on their condition. Researches of emergency life-saving systems to monitor and collect patients' location and changes of their condition...
In the current internet, Transmission Control Protocol (TCP) is used as the most popular transport layer protocol. However, the end-to-end throughput of TCP degrades significantly when operates in wireless networks. Frequent retransmission timeout is one of the well-known problems of TCP end-to-end throughput degradation over wireless networks. In wireless networks, a retransmission timeout is inevitable,...
Utilizing mobile applications in the area of industrial field service promises several benefits, especially improved process support due to a tight integration of mobile workers and tailored information support. In this paper, we describe four mobile service business patterns derived from two industrial case studies. The first case study deals with the seamless integration of service engineers, while...
Frequent partitions, intermittent connectivity and message delivery delay are the commonly observed characteristics of disruption tolerant networks (DTNs). These networks often operate over extended periods since they are regularly deployed in harsh and constrained environments. Efficient energy conservation is therefore necessary to prolong network lifetime. Most DTNs nodes depend on mobility to...
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