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Power control of secondary user is an important issue for cognitive radio systems to protect the transmission of primary users. There are several ways to protect the primary user under the accurate estimation of the channels. In this paper, we focus on the protection of primary user under the imperfect channel estimation. We first gives the mathematical expressions of the outage probability of the...
Flooding is a kind of broadcast technology in wireless sensor networks. And it is used in many occasions, such as routing, time synchronization and so on. But large-scale and intense flooding may cause broadcast storm, which aggravates the resource consumption in wireless sensor networks and leads to network congestion. In this paper, we propose a cross-layer flooding strategy for wireless sensor...
The MAC protocol for wireless sensor networks is different from traditional wireless MACs such as IEEE 802.11. Energy conservation is one of the most important goals, while per-node fairness and latency are less important. This paper proposes an adaptive transmit power scheme based on S-MAC named ATPM (Adaptive Transmit Power MAC). In S-MAC, all the nodes transmit data with a fixed power level, no...
Energy efficiency is one of the most concerned issues in wireless sensor networks, and periodic listen/sleep mechanism is widely used to reduce energy consumption. But fixed listen/sleep scheme also introduces additional latency in packet delivery and waste of energy for unnecessary idle listening. In this paper, we propose a low latency and energy efficient MAC protocol with an adaptive listen/sleep...
In this paper, we propose an improved adaptive MAC protocol for wireless sensor networks based on cross-layer architecture. The new protocol is inspired by SMAC, probably the most well-known sensor MAC scheme for energy efficiency. In the proposed new protocol, two major changes are made in original SMAC protocol, one is continual data transmission, and the other is graded contention window. The new...
Channel estimation plays an important role in wireless OFDM systems. This paper studies the channel order estimation problem, which aims to estimate the number of paths of wireless channels. We first introduce the traditional channel order estimation method based on minimum description length (MDL) criterion. We find that the traditional method do not perform well when the number of channel samples...
In this letter, an Opportunistic Interference Cancellation (OIC) is first introduced as a rate control strategy for secondary user in cognitive wireless networks. Based on the OIC rate control method, an optimal power control strategy for multichannel cognitive wireless networks is proposed. The algorithm aims to maximize the total transmit rate of cognitive user through appropriately controlling...
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