Michele Luglio | "Tor Vergata" University of Rome (original) (raw)

Papers by Michele Luglio

Mobile ad hoc networks (MANETs) are characterized by their intrinsic capability to be set up with... more Mobile ad hoc networks (MANETs) are characterized by their intrinsic capability to be set up without needing any kind of infrastructure, allowing a high degree of flexibility both at technological level and at application and service level. For this reason they are particularly useful in environment where no fixed network infrastructure is available. For example, they are well suitable for emergency application, when fixed telecommunication infrastructures, whereas present, can be seriously damaged or destroyed. Satellite networks also work without terrestrial infrastructure, excluding one gateway localized inside the footprint, and are easy to be set up too. For the same reasons also satellites can be fruitfully be utilized in case of emergency. Nevertheless, these two technologies are not in competition, as they might appear, but absolutely complementary. In fact, ad hoc mobile networks are characterized by very small terminals, low consumption, limited capacity per user terminals...

Digital Satellite Communications, 2007

2015 38th International Conference on Telecommunications and Signal Processing (TSP), 2015

Both HAPS and satellite as stand alone systems represent a flexible infrastructure to provide tel... more Both HAPS and satellite as stand alone systems represent a flexible infrastructure to provide telecommunication capabilities for a broad set of services. Nevertheless, each of the two technologies can greatly help the other to reduce the impact of some intrinsic limitation in performance. For example, the use of HAPS as intermediate point of access can greatly reduce physical layer requirements for the user terminal and can reduce the perceived latency while the satellite can be effectively used to interconnect HAPSs among one another in a cluster or to connect the HAPS with a very remote location, thus enhancing the actual coverage capability. For these and other reasons an integrated architecture looks very attractive even though complexity must be added on board the HAPS. The paper analyses advantages and disadvantages of the integrated HAPS/Satellite architecture both at system level and at service level. Moreover, the results of design activities at physical layer (link budget) and at transport layer (TCP protocol) will be shown.

The ever growing use of Internet applications (e.g., email, file transfer, remote access and web ... more The ever growing use of Internet applications (e.g., email, file transfer, remote access and web browsing) is causing progressive congestion of telecommunication networks.

The peculiar characteristics of the satellite links affect performance of the TCP protocol, large... more The peculiar characteristics of the satellite links affect performance of the TCP protocol, largely used by most of the Internet applications. Then, to achieve good performance TCP Performance Enhancing Proxy mechanisms are often used. In principle, a TCP PEP mechanism accelerates TCP transfers requiring access to TCP headers in intermediate nodes. As a drawback, this conflicts with IPsec, which requires end to end semantic be respected. ML-IPsec has been identified as a suitable trade-off solution which can mitigate such a conflict. This paper addresses security issues for satellite systems highlighting the need to guarantee both security and performance. Finally, performance of different security schemes, carried out through simulations, are shown.

Transmission Control Protocol is the layer 4 protocol over which all the Internet applications ar... more Transmission Control Protocol is the layer 4 protocol over which all the Internet applications are based. The high latency severely limits performance, especially if high bandwidth is available. Due to the high Bandwidth Delay Product a long time to fill the pipe is needed. To counteract such impairments many solutions have been proposed and some of them are actually implemented in real systems. These solutions are based either on the modification of the mechanism, mainly the flow control, or on the architecture, mainly on splitting the connection, which may even include the use of proprietary protocols. In both cases, the features of the Operative Systems of the end machines play a very important role because the dimension of the available buffer determines the initial slow start threshold and in general limits the performance of the flow control mechanism. Moreover, real scenarios may include both a single TCP session and multiple session per link. In the former case performance are only limited by the latency and by the error rate while in the latter case the simultaneous sessions can further degrade overall performance if fairness and friendliness of different schemes are not so excellent. In this paper, after describing the main solutions proposed or adopted to improve TCP performance over satellite links, we will present the main results of the optimization of the buffer dimension. Then, we will analyze through simulations the performance of the main TCP schemes with respect to real OS in case of single flow per link. Finally, we approach a scenario with many TCP connections in competition for the available bandwidth in a satellite link. In fact, a fair sharing of resources is suitable in a best-effort Internet environment where there are competing TCP flows.

2015 38th International Conference on Telecommunications and Signal Processing (TSP), 2015

ABSTRACT SPDY is a new application technology, introduced by Google, to accelerate Web transfers ... more ABSTRACT SPDY is a new application technology, introduced by Google, to accelerate Web transfers over common internet links. Most of the SPDY techniques (i.e. header compression, pushing and multiplexing) are usually included in satellite Performance Enhancing Proxies (PEPs) to optimize performance. Therefore, SPDY over satellite is expected to improve performance but without the need of any specific modification over the network. Proof of such an improvement is revolutionary for the role of satellite in the future Internet, since it could be considered as a transparent link, which does not need ad-hoc protocol adaptations. This paper addresses Web performance over satellite using the new SPDY protocol. Performance assessment relies on a satellite emulator that reproduces in software a DVB-RCS link while running real implementations of both TCP/IP stacks and SPDY.

2007 International Workshop on Satellite and Space Communications, 2007

Two aspects of DVB-RCS standard can worsen performance of TCP data connections: DAMA access schem... more Two aspects of DVB-RCS standard can worsen performance of TCP data connections: DAMA access scheme, since it introduces additional and variable delay to the already significant propagation delay and the adoption of Adaptive Coding on the return link to maximize bandwidth efficiency to face variable weather conditions, because it results in variable bandwidth allocation. Both aspects can severely impact TCP performance, especially for what concerns flow adaptation to varying channel conditions and channel usage efficiency. To optimize performance, in this paper cross-layer signaling among transport, MAC and physical layers of a DVB-RCS system is addressed. In particular MAC-TCP cross-layer is analyzed through the use of NS2 network simulator, showing the possible benefit in a DVB-RCS scenario.

The rapid evolution of the Web imposes the need of enhancing the HTTP over satellite channels. To... more The rapid evolution of the Web imposes the need of enhancing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solution to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indicate that SPDY could be an effective solution to deliver Web contents over satellites in a more �efficient manner.

Mobile ad hoc networks (MANETs) are characterized by their intrinsic capability to be set up with... more Mobile ad hoc networks (MANETs) are characterized by their intrinsic capability to be set up without needing any kind of infrastructure, allowing a high degree of flexibility both at technological level and at application and service level. For this reason they are particularly useful in environment where no fixed network infrastructure is available. For example, they are well suitable for emergency application, when fixed telecommunication infrastructures, whereas present, can be seriously damaged or destroyed. Satellite networks also work without terrestrial infrastructure, excluding one gateway localized inside the footprint, and are easy to be set up too. For the same reasons also satellites can be fruitfully be utilized in case of emergency. Nevertheless, these two technologies are not in competition, as they might appear, but absolutely complementary. In fact, ad hoc mobile networks are characterized by very small terminals, low consumption, limited capacity per user terminals...

Digital Satellite Communications, 2007

2015 38th International Conference on Telecommunications and Signal Processing (TSP), 2015

Both HAPS and satellite as stand alone systems represent a flexible infrastructure to provide tel... more Both HAPS and satellite as stand alone systems represent a flexible infrastructure to provide telecommunication capabilities for a broad set of services. Nevertheless, each of the two technologies can greatly help the other to reduce the impact of some intrinsic limitation in performance. For example, the use of HAPS as intermediate point of access can greatly reduce physical layer requirements for the user terminal and can reduce the perceived latency while the satellite can be effectively used to interconnect HAPSs among one another in a cluster or to connect the HAPS with a very remote location, thus enhancing the actual coverage capability. For these and other reasons an integrated architecture looks very attractive even though complexity must be added on board the HAPS. The paper analyses advantages and disadvantages of the integrated HAPS/Satellite architecture both at system level and at service level. Moreover, the results of design activities at physical layer (link budget) and at transport layer (TCP protocol) will be shown.

The ever growing use of Internet applications (e.g., email, file transfer, remote access and web ... more The ever growing use of Internet applications (e.g., email, file transfer, remote access and web browsing) is causing progressive congestion of telecommunication networks.

The peculiar characteristics of the satellite links affect performance of the TCP protocol, large... more The peculiar characteristics of the satellite links affect performance of the TCP protocol, largely used by most of the Internet applications. Then, to achieve good performance TCP Performance Enhancing Proxy mechanisms are often used. In principle, a TCP PEP mechanism accelerates TCP transfers requiring access to TCP headers in intermediate nodes. As a drawback, this conflicts with IPsec, which requires end to end semantic be respected. ML-IPsec has been identified as a suitable trade-off solution which can mitigate such a conflict. This paper addresses security issues for satellite systems highlighting the need to guarantee both security and performance. Finally, performance of different security schemes, carried out through simulations, are shown.

Transmission Control Protocol is the layer 4 protocol over which all the Internet applications ar... more Transmission Control Protocol is the layer 4 protocol over which all the Internet applications are based. The high latency severely limits performance, especially if high bandwidth is available. Due to the high Bandwidth Delay Product a long time to fill the pipe is needed. To counteract such impairments many solutions have been proposed and some of them are actually implemented in real systems. These solutions are based either on the modification of the mechanism, mainly the flow control, or on the architecture, mainly on splitting the connection, which may even include the use of proprietary protocols. In both cases, the features of the Operative Systems of the end machines play a very important role because the dimension of the available buffer determines the initial slow start threshold and in general limits the performance of the flow control mechanism. Moreover, real scenarios may include both a single TCP session and multiple session per link. In the former case performance are only limited by the latency and by the error rate while in the latter case the simultaneous sessions can further degrade overall performance if fairness and friendliness of different schemes are not so excellent. In this paper, after describing the main solutions proposed or adopted to improve TCP performance over satellite links, we will present the main results of the optimization of the buffer dimension. Then, we will analyze through simulations the performance of the main TCP schemes with respect to real OS in case of single flow per link. Finally, we approach a scenario with many TCP connections in competition for the available bandwidth in a satellite link. In fact, a fair sharing of resources is suitable in a best-effort Internet environment where there are competing TCP flows.

2015 38th International Conference on Telecommunications and Signal Processing (TSP), 2015

ABSTRACT SPDY is a new application technology, introduced by Google, to accelerate Web transfers ... more ABSTRACT SPDY is a new application technology, introduced by Google, to accelerate Web transfers over common internet links. Most of the SPDY techniques (i.e. header compression, pushing and multiplexing) are usually included in satellite Performance Enhancing Proxies (PEPs) to optimize performance. Therefore, SPDY over satellite is expected to improve performance but without the need of any specific modification over the network. Proof of such an improvement is revolutionary for the role of satellite in the future Internet, since it could be considered as a transparent link, which does not need ad-hoc protocol adaptations. This paper addresses Web performance over satellite using the new SPDY protocol. Performance assessment relies on a satellite emulator that reproduces in software a DVB-RCS link while running real implementations of both TCP/IP stacks and SPDY.

2007 International Workshop on Satellite and Space Communications, 2007

Two aspects of DVB-RCS standard can worsen performance of TCP data connections: DAMA access schem... more Two aspects of DVB-RCS standard can worsen performance of TCP data connections: DAMA access scheme, since it introduces additional and variable delay to the already significant propagation delay and the adoption of Adaptive Coding on the return link to maximize bandwidth efficiency to face variable weather conditions, because it results in variable bandwidth allocation. Both aspects can severely impact TCP performance, especially for what concerns flow adaptation to varying channel conditions and channel usage efficiency. To optimize performance, in this paper cross-layer signaling among transport, MAC and physical layers of a DVB-RCS system is addressed. In particular MAC-TCP cross-layer is analyzed through the use of NS2 network simulator, showing the possible benefit in a DVB-RCS scenario.

The rapid evolution of the Web imposes the need of enhancing the HTTP over satellite channels. To... more The rapid evolution of the Web imposes the need of enhancing the HTTP over satellite channels. To this aim, SPDY is a protocol engineered to reduce download times of content rich pages, as well as for managing links characterized by large Round Trip Times (RTTs) and high packet losses. With such features, it could be an efficient solution to cope with performance degradations of HTTP over satellite. In this perspective, this paper compares the behaviors of HTTP and SPDY over a DVB-RCS satellite link. To conduct a thorough set of tests over a realistic scenario, we used the Satellite Network Emulation Platform (SNEP). In addition, we evaluated how different Bandwidth on Demand (BoD) methods impact over the retrieval of a page. Results clearly indicate that SPDY could be an effective solution to deliver Web contents over satellites in a more �efficient manner.