Transmission of block-coded images through error-prone wireless channels often results in lost bl... more Transmission of block-coded images through error-prone wireless channels often results in lost blocks. In this study, we investigate a novel error concealment method for covering up these high packet losses and reconstructing a close approximation. Our scheme is a modified discrete wavelet transform (DWT) technique (namely, subbands based image error concealment (SIEC)) for embedding downsized replicas of original image into itself. We propose that this technique can be implemented for wireless channels to combat degradations in a backward-compatible scheme. We show that the proposed error concealment technique is promising, especially for the erroneous channels causing a wider range of packet losses, at the expense of computational burden
In this paper, we propose a new three-tier satellite multicast security protocol based on ECMQV (... more In this paper, we propose a new three-tier satellite multicast security protocol based on ECMQV (elliptic curve Menezes-Qu-Vanstone) and IMC (improved Merkle cryptosystem). We make contribution to the satellite multicast security protocols in two major points. These are protocol architecture design and cryptographic methods aspects. Our protocol is specifically designed for multicast systems having very large number of members and highly dynamic member join leave characteristic. Our protocol minimizes the rekeying workload of satellite layers and shows high performance for many criteria using three independent key distribution layers. In addition, our protocol uses a different cryptographic method for each layer and achieves major cryptographic goals together that are not provided in implementations of some other protocols. Using ECMQV and especially IMC based methods in satellite multicast security protocols is a novel approach and has many advantages
In this paper, we propose a new satellite multicast security protocol based on ECPVSS (Elliptic C... more In this paper, we propose a new satellite multicast security protocol based on ECPVSS (Elliptic Curve Pintsov-Vanstone Signature Scheme). Our protocol is especially designed for satellite multicast systems having very large member size as well as highly dynamic member join-leave characteristic. We design two independent key distribution layered architecture that has many advantages over classical satellite multicast systems. Our protocol significantly reduces rekeying workload of satellite multicast systems. The number of keys that are stored on the satellite is also reduced. As a novel approach for secure key transmission, we utilize ECPVSS to provide major cryptographic goals while significantly reducing bandwidth consumption. We show that the proposed protocol can handle very large multicast system securely and effectively while providing additional advantages when compared to some widely accepted protocols.
This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention ... more This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention resolution techniques in a low earth orbit (LEO) satellite constellation in terms of throughput and fairness for both uniform and bursty traffic models. In order to make such an evaluation, it is crucial to find out how thoughtput and packet drop ratio is affected by various parameters, i.e. implementation of buffers at each satellite, number of transmitters per satellite, instantenous network traffic load, type of the traffic (bursty vs uniform), and the burst size for non-uniform traffic. Simulations are made to investigate the effects of these parameters. Moreover, simulation results are plotted to better illustrate these effects on throughput and fairness of packet contention resolutions schemes and routing algorithms. The contention resolution schemes emloyed during simulations are Shortest Hop Win (SHW), Oldest Packet Win (OPW)and Random Packet Win (RPW) proposed in [1]. The routing algorithms used are static routing and adaptive routing described in [2] and semi-adaptive routing developed during the simulations.
This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention ... more This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention resolution techniques in a low earth orbit (LEO) satellite constellation in terms of throughput and fairness for both uniform and bursty traffic models. In order to make such an evaluation, it is crucial to find out how thoughtput and packet drop ratio is affected by various parameters, i.e. implementation of buffers at each satellite, number of transmitters per satellite, instantenous network traffic load, type of the traffic (bursty vs uniform), and the burst size for non-uniform traffic. Simulations are made to investigate the effects of these parameters. Moreover, simulation results are plotted to better illustrate these effects on throughput and fairness of packet contention resolutions schemes and routing algorithms. The contention resolution schemes emloyed during simulations are Shortest Hop Win (SHW), Oldest Packet Win (OPW)and Random Packet Win (RPW) proposed in [1]. The routing algorithms used are static routing and adaptive routing described in [2] and semi-adaptive routing developed during the simulations.
Virtual node (VN) approach is widely used in satellite networks research but it has some deficien... more Virtual node (VN) approach is widely used in satellite networks research but it has some deficiencies. In this work, we enhanced VN technique and propose a generic virtual topology model, namely multi-state virtual network (MSVN) architecture. We investigate a new mathematical model for MSVN and present its potential contribution to the overall system availability.
Virtual node (VN) approach is widely used in satellite networks research but it has some deficien... more Virtual node (VN) approach is widely used in satellite networks research but it has some deficiencies. In this work, we enhanced VN technique and propose a generic virtual topology model, namely multi-state virtual network (MSVN) architecture. We investigate a new mathematical model for MSVN and present its potential contribution to the overall system availability.
In this paper we investigate the beam management solution approach. Section IV gives the numerica... more In this paper we investigate the beam management solution approach. Section IV gives the numerical results and issue for providing optimal mapping between ground and space Section V concludes this work.
In this paper we investigate the beam management solution approach. Section IV gives the numerica... more In this paper we investigate the beam management solution approach. Section IV gives the numerical results and issue for providing optimal mapping between ground and space Section V concludes this work.
Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizi... more Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizing IP over Satellite (IPoS) network resources. Since there could be many shortest paths between two satellites, an efficient routing algorithm should provide better utilization of these paths. For this purpose, we propose a Priority-based Adaptive Routing (PAR) technique, which distributedly sets the shortest path through a destination. In this technique, a direction decision is made at each hop by a priority mechanism, depending on the past utilization and buffering information about the links. We further make some enhancements on PAR, and propose ePAR algorithm that also accounts for the contentions between packets with different source-destination pairs. We explore the performances of PAR and ePAR algorithms based on an extensive set of simulations, and compared their performances with static and adaptive routing techniques as a reference. Obtained results show that while the proposed PAR algorithm is promising for use in LEO satellite networks, ePAR algorithm may be more suitable for MEO satellite networks.
Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizi... more Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizing IP over Satellite (IPoS) network resources. Since there could be many shortest paths between two satellites, an efficient routing algorithm should provide better utilization of these paths. For this purpose, we propose a Priority-based Adaptive Routing (PAR) technique, which distributedly sets the shortest path through a destination. In this technique, a direction decision is made at each hop by a priority mechanism, depending on the past utilization and buffering information about the links. We further make some enhancements on PAR, and propose ePAR algorithm that also accounts for the contentions between packets with different source-destination pairs. We explore the performances of PAR and ePAR algorithms based on an extensive set of simulations, and compared their performances with static and adaptive routing techniques as a reference. Obtained results show that while the proposed PAR algorithm is promising for use in LEO satellite networks, ePAR algorithm may be more suitable for MEO satellite networks.
Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft ha... more Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft handover a b s t r a c t Handling network mobility in a highly dynamic LEO satellite network is a critical issue to achieve seamless and efficient integration of satellite and terrestrial networks. In Earthfixed satellite systems, this task could be simplified by representing the network with a more static virtual topology. Virtual node (VN) approach is widely explored in satellite networks research; however, it has some deficiencies due to necessity of one-to-one correspondence between virtual nodes and physical satellites. In this work, a generic virtual topology model, namely multi-state virtual network (MSVN) architecture that alleviates these deficiencies, is proposed. A new mathematical model for MSVN is introduced along with its potential contribution to the overall system availability. Furthermore, possible handover mechanisms in Earth-fixed satellite systems are investigated, and new efficient handover mechanisms for both VN-based systems and MSVN-based systems are proposed. Comparing the handover mechanisms, we conclude with the benefits of using an MSVNbased Earth-fixed satellite system.
Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may hav... more Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may have great potential in the next generation telecommunication services. In this paper, we focus on establishment of optical links between HAPs and mobile satellites with limited number of optical transmitters. We formulate an optimization problem for matching HAPs and satellites in such a way that the utilization of HAPs is maximized together with the average elevation angle between HAPs and satellites. We also propose a method to avoid frequent switching of optical links. We solve the problem in a sample scenario for various system parameters, and discuss the reasonable selection of these variables.
Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft ha... more Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft handover a b s t r a c t Handling network mobility in a highly dynamic LEO satellite network is a critical issue to achieve seamless and efficient integration of satellite and terrestrial networks. In Earthfixed satellite systems, this task could be simplified by representing the network with a more static virtual topology. Virtual node (VN) approach is widely explored in satellite networks research; however, it has some deficiencies due to necessity of one-to-one correspondence between virtual nodes and physical satellites. In this work, a generic virtual topology model, namely multi-state virtual network (MSVN) architecture that alleviates these deficiencies, is proposed. A new mathematical model for MSVN is introduced along with its potential contribution to the overall system availability. Furthermore, possible handover mechanisms in Earth-fixed satellite systems are investigated, and new efficient handover mechanisms for both VN-based systems and MSVN-based systems are proposed. Comparing the handover mechanisms, we conclude with the benefits of using an MSVNbased Earth-fixed satellite system.
Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, beca... more Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, because satellite network resources are costly and must be managed in an optimal and effective manner. Because of the particular features of satellite networks, such as dynamic topology, non-homogeneous traffic distribution, limited power and processing capabilities, and high propagation delays, new routing approaches should be developed. In this article, we first examine these properties with particular emphasis on their effect on the routing ...
Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may hav... more Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may have great potential in the next generation telecommunication services. In this paper, we focus on establishment of optical links between HAPs and mobile satellites with limited number of optical transmitters. We formulate an optimization problem for matching HAPs and satellites in such a way that the utilization of HAPs is maximized together with the average elevation angle between HAPs and satellites. We also propose a method to avoid frequent switching of optical links. We solve the problem in a sample scenario for various system parameters, and discuss the reasonable selection of these variables.
Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, beca... more Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, because satellite network resources are costly and must be managed in an optimal and effective manner. Because of the particular features of satellite networks, such as dynamic topology, non-homogeneous traffic distribution, limited power and processing capabilities, and high propagation delays, new routing approaches should be developed. In this article, we first examine these properties with particular emphasis on their effect on the routing ...
Transmission of block-coded images through error-prone wireless channels often results in lost bl... more Transmission of block-coded images through error-prone wireless channels often results in lost blocks. In this study, we investigate a novel error concealment method for covering up these high packet losses and reconstructing a close approximation. Our scheme is a modified discrete wavelet transform (DWT) technique (namely, subbands based image error concealment (SIEC)) for embedding downsized replicas of original image into itself. We propose that this technique can be implemented for wireless channels to combat degradations in a backward-compatible scheme. We show that the proposed error concealment technique is promising, especially for the erroneous channels causing a wider range of packet losses, at the expense of computational burden
In this paper, we propose a new three-tier satellite multicast security protocol based on ECMQV (... more In this paper, we propose a new three-tier satellite multicast security protocol based on ECMQV (elliptic curve Menezes-Qu-Vanstone) and IMC (improved Merkle cryptosystem). We make contribution to the satellite multicast security protocols in two major points. These are protocol architecture design and cryptographic methods aspects. Our protocol is specifically designed for multicast systems having very large number of members and highly dynamic member join leave characteristic. Our protocol minimizes the rekeying workload of satellite layers and shows high performance for many criteria using three independent key distribution layers. In addition, our protocol uses a different cryptographic method for each layer and achieves major cryptographic goals together that are not provided in implementations of some other protocols. Using ECMQV and especially IMC based methods in satellite multicast security protocols is a novel approach and has many advantages
In this paper, we propose a new satellite multicast security protocol based on ECPVSS (Elliptic C... more In this paper, we propose a new satellite multicast security protocol based on ECPVSS (Elliptic Curve Pintsov-Vanstone Signature Scheme). Our protocol is especially designed for satellite multicast systems having very large member size as well as highly dynamic member join-leave characteristic. We design two independent key distribution layered architecture that has many advantages over classical satellite multicast systems. Our protocol significantly reduces rekeying workload of satellite multicast systems. The number of keys that are stored on the satellite is also reduced. As a novel approach for secure key transmission, we utilize ECPVSS to provide major cryptographic goals while significantly reducing bandwidth consumption. We show that the proposed protocol can handle very large multicast system securely and effectively while providing additional advantages when compared to some widely accepted protocols.
This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention ... more This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention resolution techniques in a low earth orbit (LEO) satellite constellation in terms of throughput and fairness for both uniform and bursty traffic models. In order to make such an evaluation, it is crucial to find out how thoughtput and packet drop ratio is affected by various parameters, i.e. implementation of buffers at each satellite, number of transmitters per satellite, instantenous network traffic load, type of the traffic (bursty vs uniform), and the burst size for non-uniform traffic. Simulations are made to investigate the effects of these parameters. Moreover, simulation results are plotted to better illustrate these effects on throughput and fairness of packet contention resolutions schemes and routing algorithms. The contention resolution schemes emloyed during simulations are Shortest Hop Win (SHW), Oldest Packet Win (OPW)and Random Packet Win (RPW) proposed in [1]. The routing algorithms used are static routing and adaptive routing described in [2] and semi-adaptive routing developed during the simulations.
This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention ... more This paper evaluates static, adaptive, and semiadaptive routing algorithms and packet contention resolution techniques in a low earth orbit (LEO) satellite constellation in terms of throughput and fairness for both uniform and bursty traffic models. In order to make such an evaluation, it is crucial to find out how thoughtput and packet drop ratio is affected by various parameters, i.e. implementation of buffers at each satellite, number of transmitters per satellite, instantenous network traffic load, type of the traffic (bursty vs uniform), and the burst size for non-uniform traffic. Simulations are made to investigate the effects of these parameters. Moreover, simulation results are plotted to better illustrate these effects on throughput and fairness of packet contention resolutions schemes and routing algorithms. The contention resolution schemes emloyed during simulations are Shortest Hop Win (SHW), Oldest Packet Win (OPW)and Random Packet Win (RPW) proposed in [1]. The routing algorithms used are static routing and adaptive routing described in [2] and semi-adaptive routing developed during the simulations.
Virtual node (VN) approach is widely used in satellite networks research but it has some deficien... more Virtual node (VN) approach is widely used in satellite networks research but it has some deficiencies. In this work, we enhanced VN technique and propose a generic virtual topology model, namely multi-state virtual network (MSVN) architecture. We investigate a new mathematical model for MSVN and present its potential contribution to the overall system availability.
Virtual node (VN) approach is widely used in satellite networks research but it has some deficien... more Virtual node (VN) approach is widely used in satellite networks research but it has some deficiencies. In this work, we enhanced VN technique and propose a generic virtual topology model, namely multi-state virtual network (MSVN) architecture. We investigate a new mathematical model for MSVN and present its potential contribution to the overall system availability.
In this paper we investigate the beam management solution approach. Section IV gives the numerica... more In this paper we investigate the beam management solution approach. Section IV gives the numerical results and issue for providing optimal mapping between ground and space Section V concludes this work.
In this paper we investigate the beam management solution approach. Section IV gives the numerica... more In this paper we investigate the beam management solution approach. Section IV gives the numerical results and issue for providing optimal mapping between ground and space Section V concludes this work.
Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizi... more Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizing IP over Satellite (IPoS) network resources. Since there could be many shortest paths between two satellites, an efficient routing algorithm should provide better utilization of these paths. For this purpose, we propose a Priority-based Adaptive Routing (PAR) technique, which distributedly sets the shortest path through a destination. In this technique, a direction decision is made at each hop by a priority mechanism, depending on the past utilization and buffering information about the links. We further make some enhancements on PAR, and propose ePAR algorithm that also accounts for the contentions between packets with different source-destination pairs. We explore the performances of PAR and ePAR algorithms based on an extensive set of simulations, and compared their performances with static and adaptive routing techniques as a reference. Obtained results show that while the proposed PAR algorithm is promising for use in LEO satellite networks, ePAR algorithm may be more suitable for MEO satellite networks.
Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizi... more Designing an efficient routing algorithm for LEO satellite constellations is crucial for optimizing IP over Satellite (IPoS) network resources. Since there could be many shortest paths between two satellites, an efficient routing algorithm should provide better utilization of these paths. For this purpose, we propose a Priority-based Adaptive Routing (PAR) technique, which distributedly sets the shortest path through a destination. In this technique, a direction decision is made at each hop by a priority mechanism, depending on the past utilization and buffering information about the links. We further make some enhancements on PAR, and propose ePAR algorithm that also accounts for the contentions between packets with different source-destination pairs. We explore the performances of PAR and ePAR algorithms based on an extensive set of simulations, and compared their performances with static and adaptive routing techniques as a reference. Obtained results show that while the proposed PAR algorithm is promising for use in LEO satellite networks, ePAR algorithm may be more suitable for MEO satellite networks.
Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft ha... more Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft handover a b s t r a c t Handling network mobility in a highly dynamic LEO satellite network is a critical issue to achieve seamless and efficient integration of satellite and terrestrial networks. In Earthfixed satellite systems, this task could be simplified by representing the network with a more static virtual topology. Virtual node (VN) approach is widely explored in satellite networks research; however, it has some deficiencies due to necessity of one-to-one correspondence between virtual nodes and physical satellites. In this work, a generic virtual topology model, namely multi-state virtual network (MSVN) architecture that alleviates these deficiencies, is proposed. A new mathematical model for MSVN is introduced along with its potential contribution to the overall system availability. Furthermore, possible handover mechanisms in Earth-fixed satellite systems are investigated, and new efficient handover mechanisms for both VN-based systems and MSVN-based systems are proposed. Comparing the handover mechanisms, we conclude with the benefits of using an MSVNbased Earth-fixed satellite system.
Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may hav... more Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may have great potential in the next generation telecommunication services. In this paper, we focus on establishment of optical links between HAPs and mobile satellites with limited number of optical transmitters. We formulate an optimization problem for matching HAPs and satellites in such a way that the utilization of HAPs is maximized together with the average elevation angle between HAPs and satellites. We also propose a method to avoid frequent switching of optical links. We solve the problem in a sample scenario for various system parameters, and discuss the reasonable selection of these variables.
Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft ha... more Keywords: Earth-fixed satellite systems Virtual topology Virtual node Handover mechanisms Soft handover a b s t r a c t Handling network mobility in a highly dynamic LEO satellite network is a critical issue to achieve seamless and efficient integration of satellite and terrestrial networks. In Earthfixed satellite systems, this task could be simplified by representing the network with a more static virtual topology. Virtual node (VN) approach is widely explored in satellite networks research; however, it has some deficiencies due to necessity of one-to-one correspondence between virtual nodes and physical satellites. In this work, a generic virtual topology model, namely multi-state virtual network (MSVN) architecture that alleviates these deficiencies, is proposed. A new mathematical model for MSVN is introduced along with its potential contribution to the overall system availability. Furthermore, possible handover mechanisms in Earth-fixed satellite systems are investigated, and new efficient handover mechanisms for both VN-based systems and MSVN-based systems are proposed. Comparing the handover mechanisms, we conclude with the benefits of using an MSVNbased Earth-fixed satellite system.
Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, beca... more Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, because satellite network resources are costly and must be managed in an optimal and effective manner. Because of the particular features of satellite networks, such as dynamic topology, non-homogeneous traffic distribution, limited power and processing capabilities, and high propagation delays, new routing approaches should be developed. In this article, we first examine these properties with particular emphasis on their effect on the routing ...
Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may hav... more Non-geostationary mobile satellite systems integrated with High Altitude Platforms (HAPs) may have great potential in the next generation telecommunication services. In this paper, we focus on establishment of optical links between HAPs and mobile satellites with limited number of optical transmitters. We formulate an optimization problem for matching HAPs and satellites in such a way that the utilization of HAPs is maximized together with the average elevation angle between HAPs and satellites. We also propose a method to avoid frequent switching of optical links. We solve the problem in a sample scenario for various system parameters, and discuss the reasonable selection of these variables.
Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, beca... more Abstract Employing an efficient routing algorithm in satellite networks is a critical issue, because satellite network resources are costly and must be managed in an optimal and effective manner. Because of the particular features of satellite networks, such as dynamic topology, non-homogeneous traffic distribution, limited power and processing capabilities, and high propagation delays, new routing approaches should be developed. In this article, we first examine these properties with particular emphasis on their effect on the routing ...
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