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Purpose Crowd network systems have been deemed as a promising mode of modern service industry and future economic society, and taking crowd network as the research object and exploring its operation mechanism and laws is of great significance for realizing the effective governance of the government and the rapid development of economy, avoiding social chaos and mutation. Because crowd network is a large-scale, dynamic and diversified online deep interconnection, its most results cannot be observed in real world, and it cannot be carried out in accordance with traditional way, simulation is of great importance to put forward related research. To solve above problems, this paper aims to propose a simulation architecture based on the characteristics of crowd network and to verify the feasibility of this architecture through a simulation example. Design/methodology/approach This paper adopts a data-driven architecture by deeply analyzing existing large-scale simulation architectures and proposes a novel reflective memory-based architecture for crowd network simulations. In this paper, the architecture is analyzed from three aspects: implementation framework, functional architecture and implementation architecture. The proposed architecture adopts a general structure to decouple related work in a harmonious way and gets support for reflection storage by connecting to different devices via reflection memory card. Several toolkits for system implementation are designed and connected by data-driven files (DDF), and these XML files constitute a persistent storage layer. To improve the credibility of simulations, VV&A (verification, validation and accreditation) is introduced into the architecture to verify the accuracy of simulation system executions. Findings Implementation framework introduces the scenes, methods and toolkits involved in the whole simulation architecture construction process. Functional architecture adopts a general structure to decouple related work in a harmonious way. In the implementation architecture, several toolkits for system implementation are designed, which are connected by DDF, and these XML files constitute a persistent storage layer. Crowd network simulations obtain the support of reflective memory by connecting the reflective memory cards on different devices and connect the interfaces of relevant simulation software to complete the corresponding function call. Meanwhile, to improve the credibility of simulations, VV&A is introduced into the architecture to verify the accuracy of simulation system executions. Originality/value This paper proposes a novel reflective memory-based architecture for crowd network simulations. Reflective memory is adopted as share memory within given simulation execution in this architecture; communication efficiency and capability have greatly improved by this share memory-based architecture. This paper adopts a data-driven architecture; the architecture mainly relies on XML files to drive the entire simulation process, and XML files have strong readability and do not need special software to read.

Replacing the batteries of wearable medical devices is an inconvenience to the user. Wireless power transfer (WPT) could be a solution for this problem. However, the structure should be compact to satisfy the wearable device requirements and the power efficiency should be as high as possible for prolonging the user experience. Besides, as algorithms embedded in these devices become more complex, the device power consumption also increases. Fulfilling these specifications in a compact structure with better efficiency is the aim of this research paper. This paper proposes a power processing module for WPT applications. This module is embedded within the WPT path to convert receiving end ac power to dc power, and to simultaneously provide multiple dc–dc power conversion for wearable medical devices. The ac–dc circuit is specifically designed using a compact topology to convert wireless ac power to stable dc power. The dc power is further regulated by different mode controls either to perform battery charging or to provide independent voltage supplies to dc loads. The integrated circuit occupies an area of 1.9 × 2.3 mm when implemented on a 0.25 μm high voltage CMOS process.

Objective High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. Approach We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. Main results The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 d. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. Significance We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but also resulted in a small, light headstage that can easily be scaled to record from hundreds of channels.

Quality of service (QoS) support in wireless data networks becomes ever more imperative in the face of rapid introduction of multimedia services into the wireless domain. In this paper, we discuss the limitations of supporting end-to-end QoS applications in the current 1x EV-DO Release 0 system. We give an overview of the newly developed CDMA2000∗ standards framework that allows flow-based QoS authorization, negotiation, admission, enforcement, and accounting for 1x EV-DO Revision A systems. We investigate key QoS techniques, with an emphasis on air interface scheduling, media access control, call/flow admission, overload control, and flow classification. A video telephony (VT) application is used to demonstrate the effectiveness of these techniques. Finally, we highlight several advancements of 1x EV-DO QoS development directions. © 2007 Alcatel-Lucent.

In this paper, we analyze multi-cell multi-user interference through a new approach. The area averaged probability density function (PDF) of interference power from one active user is evaluated. Differing from the distance membership determination, the statistical effect of hand-off is considered. The Gamma distribution is proposed to model the area averaged PDF of the interference power of an active user. An efficient method for evaluating system performance is developed. Differing from the Gaussian approximation, this method is very effective and accurate for both a large number and a small number of users. The performance of a CDMA cellular system with high quality requirements and mixed traffic is evaluated.

The authors identify a new limiting factor, hop timing error, in regard to the phase coherence for coherent frequency hopped spread spectrum (C-FHSS) communications. A phase-lock system model and the Fokker-Planck equation are applied to examine the phase acquisition process for every hop. The acquisition time in certain cases, including the worst cast, is obtained for evaluating whether the C-FHSS system is practical. The relationship between the system error performance and the acquisition time is established through the phase error tolerance bound. It is shown that the hopping rate is substantially restricted by the acquisition time. >

Most conventional optimum or good bias schemes of importance sampling may be over biased for the simulation of a class of communication systems with information feedback. A new concept of the whole estimator is introduced. In addition to the estimation variance, the confidence interval and confidence level are mainly considered as the criteria of optimizing bias schemes. The nature of new optimum bias schemes is found through rigorous analysis. >

Analyzes the multi-cell multi-user interference through a new approach. The statistical effect of hand-off is considered. Differing from the Gaussian approximation, an efficient method for evaluating the performance of a system with small number of users is developed.

We obtain both the mean and variance of multicell multiuser interference power in a CDMA cellular system with non-ideal handoff and power control. We investigate the effects of handoff operation and choice of line rate (bit transmission rate through the channel) on the Erlang capacity. We consider the call arrival statistics, user membership statistics and finite number of channels available at a base-station in our evaluation of the call dropping rate. The minimum number of channels required at a base-station to ensure a specified quality of service at a given capacity requirement is determined. System capacity is further evaluated considering both the outage probability limited by interference and call dropping rate limited by the finite number of channels.