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Passive internet of things (IoT) is the fundamentally enabling technology of promoting digital transformation and upgrading of industries.In recent years, passive IoT communication technology such as radio frequency identification has been widely used in asset management fields due to its advantages of low cost, zero power consumption, and easy deployment.In this context, passive IoT communication technology and the latest research progress were introduced, the potential evolution prospects of passive IoT were analyzed.Based on that, development bottlenecks and challenges of passive IoT communication were given, a novel passive IoT communication system with deep fusion of the cellular system was presented, and the key technology research directions of this field were proposed.It is aimed to inspire new thoughts for the development of passive IoT communication technology.

Passive backscatter communication can free wireless sensors from limited-life batteries and heavy manual maintenance, and will also reduce their hardware cost.Passive backscatter communication is one of the key technologies to realize the passive internet of things (IoT).Due to the limited resources of passive sensor nodes, how to use coding technology to improve system reliability has become a challenging problem for passive IoT.The coding and decoding technologies of passive nodes in the passive IoT were focused on.Firstly, the development history of traditional channel coding and the existing RFID channel coding and decoding schemes were systematically expounded.Then, three suitable coding schemes were selected for passive backscatter communication technology.Finally, the performance of these three encoding schemes were compared by simulation and the advantages and disadvantages were summarized.

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In order to address the unfair user-centric energy efficiency (EE) problem caused by channel difference in the backscatter-assisted wireless powered communication network,a resource allocation scheme was proposed.Firstly,a mixed integer nonconvex fractional programming problem was formulated to maximize the minimum user-centric EE,subject to the quality of service and energy-causality constraints.Based on the generalized fractional programming theory,the original problem was transformed into a mixed integer nonconvex subtraction problem.With the aid of the slack variable,the proof by contradiction,the auxiliary variable and the mixed integer nonconvex subtraction problem were further transformed into an equivalent convex problem.Finally,an iterative algorithm was proposed to obtain the optimal solutions.Computer simulations validated the quick convergence of the proposed iterative algorithm,and that the developed resource allocation scheme efficiently guarantees the fairness among users in terms of EE.

Copyright of Journal on Communication / Tongxin Xuebao is the property of Journal on Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposed a method of acquiring depth information which combined the technology of polarization with the technology of ICA for the problem of underwater image degradation. The method processed the acquired polarization images based on the model of ICA, structured the linear relationship between the polarization degrees of backscatter light and the known polarization information. Then it obtaind the degree of polarization of the backscatter light by optimizing the objective function. Finally it used the method of soft matting to obtain optimized depth information of scene. Experimental results show that this method can acquire more information of target from the acquired depth image in the underwater scene and operate more efficiency. [ABSTRACT FROM AUTHOR]

The feasibility of ultrasound backscatter homodyned K model parametric imaging (termed homodyned K imaging) to monitor coagulation zone during microwave ablation was investigated. Two recent estimators for the homodyned K model parameter, RSK (the estimation method based on the signal-to-noise ratio, the skewness, and the kurtosis of the amplitude envelope of ultrasound) and XU (the estimation method based on the first moment of the intensity of ultrasound, X statistics and U statistics), were compared. Firstly, the ultrasound backscattered signals during the microwave ablation of porcine liver ex vivo were processed by the noise-assisted correlation algorithm, envelope detection, sliding window method, digital scan conversion and color mapping to obtain homodyned K imaging. Then 20 porcine livers' microwave ablation experiments ex vivo were used to evaluate the effect of homodyned K imaging in monitoring the coagulation zone. The results showed that the area under the receiver operating characteristic curve of the RSK method was 0.77 ± 0.06 (mean ± standard deviation), and that of the XU method was 0.83 ± 0.08 (mean ± standard deviation). The accuracy to monitor the coagulation zone was (86 ± 10)% (mean ± standard deviation) by the RSK method and (90 ± 8)% (mean ± standard deviation) by the XU method. Compared with the RSK method, the Bland-Altman consistency for the coagulation zone estimated by the XU method and that of actual porcine liver tissue was higher. The time for parameter estimation and imaging by the XU method was less than that by the RSK method. We conclude that ultrasound backscatter homodyned K imaging can be used to monitor coagulation zones during microwave ablation, and the XU method is better than the RSK method.