We compare the performances of two diierent routing schemes for LEO satellite networks through simulation. The rst one is a dynamic routing scheme based on the shortest-path algorithm. Its routing table is updated according to cost estimation based on link status information that is broadcasted periodically. The second one is an optimal routing scheme proposed by the authors of this paper, wher...

| We propose a new framework for the link assignment (i.e., topological design) problem that arises from the use of inter-satellite links (ISL's) in Low-Earth Orbit (LEO) satellite networks. In the proposed framework, we model a LEO satellite network as a Finite State Automaton (FSA) where each state corresponds to an equal-length interval in the system period of the LEO satellite network. This...

The challenge of future mobile multimedia networks is to provide worldwide tetherless communication services. Low Earth Orbit-Mobile Satellite Systems (LEO-MSSs) will play a significant role by filling the coverage gaps of future generation terrestrial cellular networks. This lecture presents research results on demand-assignment Medium Access Control (MAC) schemes able to share efficiently LEO...

Future Low Earth Orbit (LEO) satellite networks are envisioned as distributed architectures of autonomous data processing nodes. Such ad hoc networks should deliver reliable communication channels for control commands and data among ground stations and satellites minimizing delay and power. The LEO satellite networks are different from the generic ad hoc scenario. In this paper, we first analyz...

In this paper, we propose a new channel estimation algorithm for low earth orbit satellite digital communications. Low earth orbit satellite channels impart severe spreading in delay and Doppler on the transmitted signal. We model the channel as a tapped-delay-line lter with time-varying complex coeecients. The time evolution of the taps is described by an auto-regressive model. A coupled lter ...

In this paper, we discuss on two important issues through the realization of global personal communication networks with low earth orbital (LEO) satellites. The first issue is the selection of an effective multiple access scheme which can utilize the limited spectrum allocated to these systems. In this way, we focus on the schemes based on spread spectrum techniques and explain their unique cha...

Low Earth Orbit (LEO) satellites are an essential complement of the cellular radio infrastructure, especially the Universal Mobile Telecommunications System (UMTS), for mobile (pedestrian and, more important, vehicular) access to the Internet in sparsely populated areas, where high bandwidth UMTS cells cannot be economically deployed. LEO users would eventually switch between the satellite segm...

This paper describes the essential segments of a satellite based communication and asset management system. The Low Earth Orbit satellite used for such a system is the ORBCOMM low earth orbit (LEO) constellation. The architecture and network structure of the satellite system is described. The satellites themselves are very small and are launched using the Pegasus launch vehicle. This makes the ...

Previous research in satellite constellation designs has focused on Low Earth Orbit (LEO) communication systems that service a global market of uniform demand. This paper addresses the challenge of designing a hybrid satellite system constellation (e.g., LEO satellites with elliptical orbiting satellites) to meet the demands of the emerging satellite broadband market. The broadband market model...

Communication with Low-Earth Orbit (LEO) satellites requires the set up of a ground station which is a complex and costly installation. Moreover, a LEO satellite is accessible only during certain time slots from a given ground station. In other words, access to LEO satellites is on an intermittent basis and is constrained by the availability of ground stations. The work presented in this paper ...