An operational and performance overview of the IRIDIUM low earth orbit satellite system

Pratt, Stephen R.; Raines, Richard A.; Fossa, Carl; Temple, Michael A.

doi:10.1109/comst.1999.5340513

Cited by 182 publications

(88 citation statements)

References 12 publications

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“…Therefore, a dedicated Iridium-satellite (Pratt et al 1999) connection is used by the SNDAQ host system to transmit urgent alerts. In that case, a short datagram is sent to the northern hemisphere.…”

Section: The Icecube Detectormentioning

confidence: 99%

IceCube sensitivity for low-energy neutrinos from nearby supernovae

Abbasi¹,

Abdou²,

Abu‐Zayyad³

et al. 2011

A&A

139

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This paper describes the response of the IceCube neutrino telescope located at the geographic south pole to outbursts of MeV neutrinos from the core collapse of nearby massive stars. IceCube was completed in December 2010 forming a lattice of 5160 photomultiplier tubes that monitor a volume of ∼1 km 3 in the deep Antarctic ice for particle induced photons. The telescope was designed to detect neutrinos with energies greater than 100 GeV. Owing to subfreezing ice temperatures, the photomultiplier dark noise rates are particularly low. Hence IceCube can also detect large numbers of MeV neutrinos by observing a collective rise in all photomultiplier rates on top of the dark noise. With 2 ms timing resolution, IceCube can detect subtle features in the temporal development of the supernova neutrino burst. For a supernova at the galactic center, its sensitivity matches that of a background-free megaton-scale supernova search experiment. The sensitivity decreases to 20 standard deviations at the galactic edge (30 kpc) and 6 standard deviations at the Large Magellanic Cloud (50 kpc). IceCube is sending triggers from potential supernovae to the Supernova Early Warning System. The sensitivity to neutrino properties such as the neutrino hierarchy is discussed, as well as the possibility to A109, page 1 of 18 detect the neutronization burst, a short outbreak of ν e 's released by electron capture on protons soon after collapse. Tantalizing signatures, such as the formation of a quark star or a black hole as well as the characteristics of shock waves, are investigated to illustrate IceCube's capability for supernova detection.

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Section: The Icecube Detectormentioning

confidence: 99%

IceCube sensitivity for low-energy neutrinos from nearby supernovae

Abbasi¹,

Abdou²,

Abu‐Zayyad³

et al. 2011

A&A

139

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“…This is because the mean delay of 81 msec is far much below the recommended maximum mean delay of 400 msec by ITU [9] for voice and video customers.…”

Section: Scenario 1 Resultsmentioning

confidence: 91%

Enabling Communication in Developing Regions

Yavwa

Kritzinger

2001

E J Info Sys Dev Countries

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The lack of communication facilities in developing countries is a constraint to social, political and economic empowerment of the people. However, advances in technology promise to deliver voice, video and data communication services, that are urgently needed, under a common packet switched communication network. Using Zambia as a case study, the cost effectiveness of three design scenarios which involve a hybrid of radio and microwave, radio and satellite, and radio and optic fibre were evaluated. The communication links in each scenario were modeled as E1 trunks. The cost of establishing these links was determined. Each scenario was then subjected to generic input traffic patterns using a multiclass queueing network analysis model to determine its effectiveness. Our findings show that the scenario involving the microwave links as inter-regional links has the lowest cost. The second is the scenario involving satellite inter-regional links and the most expensive is the scenario involving optic fibre inter-regional links. Furthermore, the microwave-radio hybrid scenario was found to have the smallest cost-effectiveness ratio of 17.9 followed by the optic fibreradio scenario with 20.3 and finally the satellite-radio scenario with 892.9. These results effectively imply that the microwave-radio hybrid scenario is a better option for developing countries..

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“…The ideal constellation is assumed to be the Iridium constellation, 30 which has a period of baseline traffic variation that is approximately equal to 24 h. Because the Iridium constellation has 66 satellites equally distributed in six planes, we correspondingly divide the Earth into 6 3 11 geographical zones as shown in Figure 1. To hide the complex repercussions caused by the mobility of satellites when modeling the baseline, we adopt the virtual satellite mechanism.…”

Section: Predictable Long-range Baselinementioning

confidence: 99%

“…Their traffic requirement, which is closely related to geographical distribution of IoT devices, the daily evolution of traffic intensity, and the coverage relationship between satellites and geographical zones show strong periodical and predictable features. [28][29][30] This suggests that the amount of traffic that needs to be routed by each satellite at a particular time can be approximately estimated. Henceforth, load balancing routing schemes should take this into account and take measures in advance to prevent traffic concentration as opposed to reacting to the onset of congestion.…”

Section: Introductionmentioning

confidence: 99%

HGL: A hybrid global-local load balancing routing scheme for the Internet of Things through satellite networks

Liu

Wang

et al. 2017

International Journal of Distributed Sensor Networks

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Satellite networks provide complete connectivity and worldwide data transmission capability for constructing the Internet of Things. However, because of the varying Internet of Things traffic density, satellite networks may endure imbalanced traffic requirements and frequent link congestion. To effectively resolve these problems and optimally transmit Internet of Things data, a novel hybrid global-local load balancing routing scheme for Low Earth Orbit satellite networks is proposed in this article. Hybrid global-local load balancing routing scheme enables satellites to route Internet of Things traffic through global planning and local real-time adjustments in two steps. In hybrid global-local load balancing routing scheme, given the predictive nature of Internet of Things traffic distribution and Low Earth Orbit satellite networks, the inter-satellite traffic demand is decomposed into a predictable long-range baseline and unpredictable shortrange fluctuations. A global strategy is employed first for preliminary global traffic allocation based on long-range baselines, and a local strategy is then employed for route adjustments based on short-range fluctuations. With the combination of global planning and local real-time adjustments, network traffic can eventually obtain a near-optimal allocation. Numerical simulations indicate that in contrast to single-strategy schemes, hybrid global-local load balancing routing scheme can more thoroughly eliminate congestion, and it performs better in measures such as packet loss rate, average queuing delay, traffic distribution, route oscillation, and communication overhead.

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An operational and performance overview of the IRIDIUM low earth orbit satellite system

Cited by 182 publications

References 12 publications

IceCube sensitivity for low-energy neutrinos from nearby supernovae

IceCube sensitivity for low-energy neutrinos from nearby supernovae

Enabling Communication in Developing Regions

HGL: A hybrid global-local load balancing routing scheme for the Internet of Things through satellite networks

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