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Pulsed thermography (PT) is a widely used non-destructive testing (NDT) technique for defect detection in carbon fiber reinforced polymers (CFRP) structures. Thermographic signal reconstruction (TSR) is often employed to process thermographic data due to its excellent performance in enhancing the contrast between defects and background. However, TSR does not reduce the noise of thermographic data...
In order to deal with the problem when the bandwidth of the passive radars and wideband digital receivers are getting bigger and bigger, causing that the traditional signal detection methods need a high sampling rate and a large number of sampling points. This paper extends the modulated wideband converter (MWC) which is recently proposed compressed sensing techniques to discrete-time domain in order...
For the problem that the sensitivity greatly reduces when the bandwidth of wideband digital receivers increases and the problem of cross-channel signal caused by uniform channelized wideband digital receivers, a new receiver based on modulated wideband converter (MWC) discrete compressed sampling structure is proposed and the proposed structure is improved to compressively sample radar signals and...
It is an important issue to design wireless communication and networking that radio resources should be efficiently utilized while providing guaranteed Quality of Service (QoS). In this area, link adaptation based on accurate channel quality estimation has attracted a lot of attention from both academia and industry. Topics such as power control, adaptive modulation and adaptive rate coding are under...
Channel quality parameters are needed to achieve efficient utilization of radio resources. These parameters include channel amplitude gain, channel frequency offset, channel random phase, channel multipath as well as channel noise variance. Usually, signal-to-noise ratio (SNR) at the demodulator output is used as channel quality indicator to link bit error rate (BER). In applications such as power...
This paper investigates energy efficiency for the two-tier femtocell networks through combining game theory and stochastic learning. With the Stackelberg game formulation, a hierarchical reinforcement learning framework is developed to study the joint expected utility maximization of macrocells and femtocells. The macrocells behave as the leaders and the femtocells are followers during the learning...
As energy saving and environmental protection become an inevitable trend, researchers need to shift their focus to “green” oriented architecture design. Recent advances in the area of cognitive radio (CR) have significant potential towards “green” communications. One of the critical challenges for operating CRs in a wireless mesh network is how to efficiently allocate transmission powers and frequency...
The purpose of a multi-hop relay in WiMAX system is to enhance cell coverage, throughput and system capacity. IEEE802.16j standard specifies a multi-hop relay and IEEE802.16m standard recently considers adopting a multi-hop relay. Besides, many research groups insist that cooperative communication including transparent relay saves energy as well as brings better performance. However, they don't provide...
For WPAN (Wireless Personal Area Network) applications, a low-power low-noise IF (Intermediate-Frequency) circuit is proposed for GFSK (Gauss Frequency Shift Keying) low-IF receivers. The proposed IF system is realized by an all-analog architecture, which is composed of a couple of LAs (Limiting Amplifiers) and RSSIs (Received Signal Strength Indicators), a couple of BPFs (Band-Pass Filters), a FD...
Cognitive wireless mesh networks have great potential to green communication. One of the critical challenges for realizing such networks is how to adaptively match transmit powers and allocate frequency resources among secondary users of the licensed frequency bands whilst maintaining the quality-of-service (QoS) requirement of the primary users, even in mutually entangled interferences environment...
In this paper, we analyze the challenges of the interference environment in a hybrid network that consists of the device-to-device (D2D communication based ad-hoc connections and conventional cellular connections. Accordingly, time hopping (TH) based radio resource allocation schemes aiming to improve the robustness of the hybrid network are proposed. The performance improvement even with the simple...
In a cellular network system one way to increase its capacity is to allow direct communication between closely located user devices when they are communicating with each other instead of conveying data from one device to the other via the radio and core network. The problem is then when the network shall assign direct communication mode and when not. In previous works the decision has been done individually...
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