122 research outputs found
Quality of Service Management and Interoperability
Information technology: general issue
Performance Analysis of WebRTC-based Video Streaming over Power Constrained Platforms
This work analyses the use of the WebRTC framework on resource-constrained platforms. WebRTC is a consolidated solution for real-time video streaming, and it is an appealing solution in a wide range of application scenarios. We focus our attention on those in which power consumption, size and weight are of paramount importance because of size, weight and power requirements, such as the use case of unmanned aerial vehicles delivering real-time video streams overWebRTC to peers on the ground. The testbed described in this work shows that the power consumption can be reduced by changing WebRTC default settings while maintaining comparable video quality
Joint Beamforming and Power Allocation for Satellite-Terrestrial Integrated Networks With Non-Orthogonal Multiple Access
In this paper, we propose a joint optimization design for a non-orthogonal multiple access (NOMA)-based satellite-terrestrial integrated network (STIN), where a satellite multicast communication network shares the millimeter wave spectrum with a cellular network employing NOMA technology. By assuming that the satellite uses multibeam antenna array and the base station employs uniform planar array, we first formulate a constrained optimization problem to maximize the sum rate of the STIN while satisfying the constraint of per-antenna transmit power and quality-of-service requirements of both satellite and cellular users. Since the formulated optimization problem is NP-hard and mathematically intractable, we develop a novel user pairing scheme so that more than two users can be grouped in a cluster to exploit the NOMA technique. Based on the user clustering, we further propose to transform the non-convex problem into an equivalent convex one, and present an iterative penalty function-based beamforming (BF) scheme to obtain the BF weight vectors and power coefficients with fast convergence. Simulation results confirm the effectiveness and superiority of the proposed approach in comparison with the existing works
A Content Oriented Information Sharing System for Disaster Management
In response to natural and man-made hazards multiple organisations usually are involved in a very complex situation. On the other hand, extreme weather situations due to the climate change create hazards in areas which were considered safe before. In order to improve the capabilities of involved organisations in responding and preparing for disaster events, the availability of an efficient information sharing approach is a key enabler. To this end, we propose a communication system based on a content oriented architecture tailored to disaster management. It includes a catalogue that is offering web services for publishing and subscribing of disaster information and for further collaboration amongst agencies and first responders. Moreover, the considered approach also allows for full content access control and enables a flexible system. The paper shows the current status of the system design. Next steps will include the implementation and evaluation of the approach
Guest Editorial: Space Information Networks: Technological Challenges, Design Issues, and Solutions
It has been expected that the space information networks (SIN),
as an extension of the terrestrial network, would provide high-speed,
high-capacity, global continuous communication, and data transmission
services anywhere for anyone at any time. With rapid advances
in relevant technologies (e.g., satellite miniaturization technology,
reusable rocket launch technology, and semiconductor technology),
low-orbit satellites, drones, and airships can be integrated into
the SIN to supply more comprehensive network connectivity. The
standard development organizations including 3GPP, ITU, and ETSI
already starts corresponding standardization activities to support nonterrestrial
networks in SIN. It can be foreseen that SIN will be
expanded to provide not only telephone services but also various
kinds of Internet services, and it is thus able to serve many more
users with different demands
SPACE COMMUNICATIONS PROTOCOLS FOR FUTURE OPTICAL SATELLITE-DOWNLINKS
As telemetry downlink data rates from EO-satellites increase and available radio frequency transmission spectrum narrows, optical data downlinks based on directed modulated laser sources become a beneficial alternative. While solving the bottleneck of data rate by providing licensing-free transmission at up to multi-Gigabit per second data rates, the required onboard terminal hardware is at the same time small and uses low transmit power. However, the transmission channel is very different to RF downlinks as new atmospheric effects have to be regarded, mainly cloud blockage, increased attenuation at low elevations, and index of refraction turbulence. To enable also with optical downlinks the level of global cooperation prevailing in RF downlink operations, it is necessary to elaborate and standardize optimized optical transmission formats. We present here the characteristics of optical LEO downlinks and the requirements they impose on the transmission data formats and protocols. We consider how existing RF satellite transmission-securing formats can be adopted and extended to enable reliable and efficient optical downlinks
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