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Wireless communications are subjected to radio jamming attacks due to the fact that the transmission medium is open to any hostile attackers. In a radio jamming, an attacker can jam a channel by emitting a radio signal in certain strength without understanding the protocol. It may also try to disrupt the RF operations of a communication protocol if it understands the protocol. Detection of the jamming...
As a natural scarcity in wireless networks, radio spectrum becomes a major investment in network deployment. How to improve the channel utilization (CU) of the spectrum is a challenging topic in recent research. In network environment, the utilization of a channel is measured by the effective CU (ECU), ie., the effective time in transmission or being sensed busy over its total operation time. However,...
In a traditional cellular network, the base station (BS) plays a critical role in linking devices for communications, but the huge user demand, especially in cities, has become a cost burden to the BS. The technique of device-to-device (D2D) communications underlaying cellular networks solves this problem and adds benefits to resource utilization. Nevertheless, the issue of how to efficiently utilize...
Since the problem of optimal radio channel assignment (RCA) is NP-hard, the existing RCA algorithms have to use heuristic approaches for any networks of practical sizes. However, the algorithms suffer from two major issues, i.e., unable to consider the co-channel interference (CCI), and finding only sub-optimal assignment. In this work, we propose a new strategy to overcome the two challenging issues...
Since radio channel allocation (RCA) is usually formulated as an NP-hard problem, most existing strategies use heuristic approaches to find sub-optimum solutions with unknown complexity. As an indicator to the complexity, computational scale (CS) is defined as the number of channel reallocations until a network reaches a convergence state. In this paper, we propose a hybrid approach to evaluate the...
Simple and useful methods are described herein for a portable and multichannel preamplifier circuit. These procedures include mainly operational amplifier selection, offset voltage reduction, active guarding circuit, selectable reference node, and grounded plate arrangement. A fabricated six-channel board for intracortical activities recording using commercial components measures 4.0 cm times 8.5...
Usually, the radio channel allocation (RCA) problems of wireless LANs (WLANs) are solved by using various heuristic methods. However, it is not clear that the minmax problem is an NP-hard problem or not. In this paper, we consider WLANs with multiple APs that can be deployed in an ad hoc network. First, we propose a distributed heuristic algorithm (DHA) for RCA, which allocates channels in terms of...
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