The successful launch of Luojia 1-01 complements the existing nighttime light data with a high spatial resolution of 130 m. This paper is the first study to assess the potential of using Luojia 1-01 nighttime light imagery for investigating artificial light pollution. Eight Luojia 1-01 images were selected to conduct geometric correction. Then, the ability of Luojia 1-01 to detect artificial light pollution was assessed from three aspects, including the comparison between Luojia 1-01 and the Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS), the source of artificial light pollution and the patterns of urban light pollution. Moreover, the advantages and limitations of Luojia 1-01 were discussed. The results showed the following: (1) Luojia 1-01 can detect a higher dynamic range and capture the finer spatial details of artificial nighttime light. (2) The averages of the artificial light brightness were different between various land use types. The brightness of the artificial light pollution of airports, streets, and commercial services is high, while dark areas include farmland and rivers. (3) The light pollution patterns of four cities decreased away from the urban core and the total light pollution is highly related to the economic development. Our findings confirm that Luojia 1-01 can be effectively used to investigate artificial light pollution. Some limitations of Luojia 1-01, including its spectral range, radiometric calibration and the effects of clouds and moonlight, should be researched in future studies.
We experimentally present a proof-of-concept demonstration of OpenFlow-based wavelength path control for lightpath provisioning in transparent optical networks, assessing its overall feasibility and quantitatively evaluating the network performances. OCIS codes: (060.4250) Networks; (060.4510) Optical communications IntroductionTransparent optical networks are typically composed of nodes such as reconfigurable optical add-drop multiplexers (ROADM), wavelength cross-connect (WXC) and photonic cross-connects (PXC), which are capable of switching signals in the optical domain. In the current commercial metro/core networks, these optical nodes are controlled and managed through the element management system (EMS) and/or the network management system (NMS) in a manual and semi-static style for lightpath provisioning, as shown in Fig.1a. Although it is very reliable, the rapid increase of dynamic network traffic motivates the carriers to seek a technique that enables a dynamic and intelligent control of wavelength paths in transparent optical networks.A well-known choice is the generalized multi-protocol label switching (GMPLS), which is a stable protocol suite to automatically provision end-to-end connections in a fully distributed manner. However, GMPLS-based control plane has not been widely deployed so far, and more important, most network carriers seem to lack confidence to promote the commercial deployment of GMPLS in the optical backbone. The reasons behind this situation are complicated [1]. One of the most important reasons is that the carriers are more preferred a centralized control approach rather than distributed one for risk averse. It is because the centralized control architecture is simpler, more manageable and reliable. Moreover, the centralized control scheme is easier to migrate and update from the current NMS/EMS architecture which has been established, with huge investments already made.Recently, a new open-source protocol referred to as OpenFlow has been proposed [2] and received extensive attentions worldwide [3][4][5][6]. Although the original motivation of OpenFlow is to develop virtualized and programmable networks, it also has been widely regarded as a promising candidate for a control plane technique in heterogeneous networks for its special features [3][4][5][6]. In order to realize a dynamic optical network with centralized control architecture, in this paper, we experimentally demonstrate OpenFlow-based wavelength path control in transparent optical networks, and to the best of our knowledge, it is the first study that investigates the OpenFlow control of an optical network. The previous work with similar background can only be found in [4], in which the OpenFlow is utilized to control a single 1x9 wavelength selective switch (WSS).
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