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In this paper, a testbed design and implementation of ultra-wideband (UWB) multiple-input single-output (MISO) time-reversal system are presented. The implementation is based on field programmable gate array (FPGA). The combination of MISO with UWB time-reversal is promising for enhancing the data rate and reliability in harsh wireless environments. When multiple transmitter antennas are considered...
Application layer multicast (ALM) has resolved the issue of deployment, but effectiveness inferiors to IP multicast. In this paper, the research is focused upon the influence on the communication efficiency of the multicast tree using three kinds of node selection strategy, which are based on min-delay, max-bandwidth, and nearest network topology. This paper presents NNT, a distributed spanning tree...
We propose the framework for monitoring k-nearest neighbor (kNN) query based on peer-to-peer (P2P) structure. In the framework, moving objects with mobile equipment can finish some computation to help finding global kNN. A group-query algorithm is introduced which adopt two new techniques named distance-time and section-sort to speed-up the query. The cost of CPU time and wireless communication could...
Statistical modeling of rainfall induced temporal variations in a foliage channel at VHF frequency is performed in this paper. With the help of the Akaike weight omegaj, Weibull and Rayleigh functions are identified as the two suitable models to describe the tap amplitude variations. The Weibull function is then used as the channel model to analyze the rainfall induced temporal variations in a foliage...
This paper reports a practical design and construction of a wideband channel sounding system for air-to-ground measurements at C band. A high precision Global Positioning System (GPS) time-stamped system is developed using the virtual instrument (VI) concept. With the implementations of the spread spectrum technique and through matched filter detection, the performance of the designed sounding system...
The increasing popularity of the multimedia applications in mobile ad hoc networks (MANETs) has led to research on QoS support for these applications. However, this is difficult in such networks because of factors such as shared and variable wireless bandwidth, limited power supply and possible mobility of the nodes. Much has been done to the quality of service problem of ad hoc networks, and many...
This paper presents a wideband measurement and characterization of a tropical forested channel. Complex channel impulse response measurements were carried out at 240 MHz for static transmit and receive antennas. Measured power delay profiles indicate significant multipath components following the dominant propagating wave. Relevant parameters such as RMS delay spread, Rician K factor et al. have been...
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