Simultaneous dimming controlling and data transmission are usually required in a white LED based indoor visible light communication system.However,the diming controlling of LED normally interferes the data transmissio...Simultaneous dimming controlling and data transmission are usually required in a white LED based indoor visible light communication system.However,the diming controlling of LED normally interferes the data transmission due to the modulation nonlinearity of LED.In order to solve this problem,a scheme by separating the LEDs for the functions of dimming control and data transmission respectively is proposed in this paper.In the scheme,the LEDs used for dimming control function are driven by a dc amplified circuit,and the LEDs for data transmission are driven by a digital modulation circuit respectively.In this way,the modulation distortion to the data signal caused by the modulation nonlinearity can be avoided even if the dimming is at high level dc driven current.The proof-of-concept experiment of a 2.5Mbit/s visible light communication system demonstrates that the dimming controlling and data transmission can be realized simultaneously in a simple way,and the data transmission is not affected by the dimming controlling function.Compared to previous methods,the scheme in this paper is simpler and cost effective,and makes sense when high rate data is transmitted in a visible light communication system.展开更多
Cognition is the ability to process information, apply knowledge, and change the circumstance. Cognition is associated with intent and its accomplishment through various processes that monitor and control a system and...Cognition is the ability to process information, apply knowledge, and change the circumstance. Cognition is associated with intent and its accomplishment through various processes that monitor and control a system and its environment. Cognition is associated with a sense of “self” (the observer) and the systems with which it interacts (the environment or the “observed”). Cognition extensively uses time and history in executing and regulating tasks that constitute a cognitive process. Whether cognition is computation in the strict sense of adhering to Turing-Church thesis or needs additional constructs is a very relevant question for addressing the design of self-managing (autonomous) distributed computing systems. In this paper we argue that cognition requires more than mere book-keeping provided by the Turing machines and certain aspects of cognition such as self-identity, self-description, self-monitoring and self-management can be implemented using parallel extensions to current serial von-Neumann stored program control (SPC) Turing machine implementations. We argue that the new DIME (Distributed Intelligent Computing Element) computing model, recently introduced as the building block of the DIME network architecture, is an analogue of Turing’s O-machine and extends it to implement a recursive managed distributed computing network, which can be viewed as an interconnected group of such specialized Oracle machines, referred to as a DIME network. The DIME network architecture provides the architectural resiliency, which is often associated with cellular organisms, through auto-failover;auto-scaling;live-migration;and end-to-end transaction security assurance in a distributed system. We argue that the self-identity and self-management processes of a DIME network inject the elements of cognition into Turing machine based computing as is demonstrated by two prototypes eliminating the complexity introduced by hypervisors, virtual machines and other layers of ad-hoc management software in today’s distributed computing environments.展开更多
Based on a physical model for the radio wave propagation in multipath scattering environments, this paper analyses and simulates the propagation properties as well as time-selective behavior of radio waves in d...Based on a physical model for the radio wave propagation in multipath scattering environments, this paper analyses and simulates the propagation properties as well as time-selective behavior of radio waves in different urban microcellular mobile radio channels. The approach of propagation properties causes a generation of complex impulse responses to be like that given by the statistics of the underlying channel behavior. Fading characteristics of the multipath structures can be efficiently simulated by reproducing the physical wave interference process, thereby incorporating the different channel characteristics that are observed in different urban environments.展开更多
基金financially supported by National Natural Science Foundation of China(No.61475094)National 973 Program of China(No.2013CB329202)
文摘Simultaneous dimming controlling and data transmission are usually required in a white LED based indoor visible light communication system.However,the diming controlling of LED normally interferes the data transmission due to the modulation nonlinearity of LED.In order to solve this problem,a scheme by separating the LEDs for the functions of dimming control and data transmission respectively is proposed in this paper.In the scheme,the LEDs used for dimming control function are driven by a dc amplified circuit,and the LEDs for data transmission are driven by a digital modulation circuit respectively.In this way,the modulation distortion to the data signal caused by the modulation nonlinearity can be avoided even if the dimming is at high level dc driven current.The proof-of-concept experiment of a 2.5Mbit/s visible light communication system demonstrates that the dimming controlling and data transmission can be realized simultaneously in a simple way,and the data transmission is not affected by the dimming controlling function.Compared to previous methods,the scheme in this paper is simpler and cost effective,and makes sense when high rate data is transmitted in a visible light communication system.
文摘Cognition is the ability to process information, apply knowledge, and change the circumstance. Cognition is associated with intent and its accomplishment through various processes that monitor and control a system and its environment. Cognition is associated with a sense of “self” (the observer) and the systems with which it interacts (the environment or the “observed”). Cognition extensively uses time and history in executing and regulating tasks that constitute a cognitive process. Whether cognition is computation in the strict sense of adhering to Turing-Church thesis or needs additional constructs is a very relevant question for addressing the design of self-managing (autonomous) distributed computing systems. In this paper we argue that cognition requires more than mere book-keeping provided by the Turing machines and certain aspects of cognition such as self-identity, self-description, self-monitoring and self-management can be implemented using parallel extensions to current serial von-Neumann stored program control (SPC) Turing machine implementations. We argue that the new DIME (Distributed Intelligent Computing Element) computing model, recently introduced as the building block of the DIME network architecture, is an analogue of Turing’s O-machine and extends it to implement a recursive managed distributed computing network, which can be viewed as an interconnected group of such specialized Oracle machines, referred to as a DIME network. The DIME network architecture provides the architectural resiliency, which is often associated with cellular organisms, through auto-failover;auto-scaling;live-migration;and end-to-end transaction security assurance in a distributed system. We argue that the self-identity and self-management processes of a DIME network inject the elements of cognition into Turing machine based computing as is demonstrated by two prototypes eliminating the complexity introduced by hypervisors, virtual machines and other layers of ad-hoc management software in today’s distributed computing environments.
文摘Based on a physical model for the radio wave propagation in multipath scattering environments, this paper analyses and simulates the propagation properties as well as time-selective behavior of radio waves in different urban microcellular mobile radio channels. The approach of propagation properties causes a generation of complex impulse responses to be like that given by the statistics of the underlying channel behavior. Fading characteristics of the multipath structures can be efficiently simulated by reproducing the physical wave interference process, thereby incorporating the different channel characteristics that are observed in different urban environments.
