Abstract In heterogeneous networks, TCP connections that incorporate a terrestrial or satellite radio link are greatly disadvantaged with respect to entirely wired connections, because of their longer round trip times (RTTs). To cope this problem, new proposal, the Hybla, is presented and discussed in paper. It stems from an analytical evaluation congestion window dynamics standard versions (Tahoe, Reno, NewReno), which suggests necessary modifications remove performance dependence on RTT....

Delay- and Disruption Tolerant Networks (DTNs) are based on an overlay protocol the store-carry-forward paradigm. In practice, each DTN node can store information for a long time before forwarding it. DTNs particularly suited to cope with challenges imposed by space environment. This paper is focused routing in DTNs, particular contact graph (CGR) its most representative enhancements, available literature, which briefly surveyed this work. Moreover, applicability obtained performance of...

Satellite communications are characterized by long delays, packet losses, and sometimes intermittent connectivity link disruptions. The TCP/IP stack is ineffective against these impairments even dedicated solutions, such as performance enhancing proxies (PEPs), can hardly tackle the most challenging environments, create compatibility issues with current security protocols. An alternative solution arises from delay- disruption-tolerant networking (DTN) architecture, which specifies an overlay...

Several multisatellite and multispot systems have been recently proposed for provision of mobile personal services with global coverage, adopting GEO or non-GEO (i.e., MEO, LEO) satellite constellations. The paper addresses an in-depth analysis these constellations, evaluating both geometrical performance measures cochannel interference levels caused by extensive frequency reuse. yields the statistics hand-overs, link absence periods. is based on a general model valid all access techniques,...

Delay-/Disruption-Tolerant Networking, which originated from research on deep space communications, has enlarged its scope to encompass all challenged networks, including LEO satellite communications. Focusing single or incomplete constellation cases, the advantages of DTN mainly relate ability cope with disruption and intermittent connectivity, typical LEOs. This, however, requires adoption routing solutions specifically designed for DTNs. Among many proposals, Contact Graph Routing, by...

Satellite communications pose serious challenges to transport layer performance, mainly because of long propagation delays (especially in geosynchronous systems) and the possi ble presence random errors on satellite link. Solutions that cope with these impairments usually rely upon either adoption enhanced versions protocols, or insertion intermediate agents, like PEPs (Performance Enhancing Proxies). An alternative approach is adopt DTN (Delay/Disruption Tolerant Networking) architecture...

In this paper we present two enhancements to Contact Graph Routing (CGR), a Delay-/ Disruption- Tolerant Networking routing algorithm developed by NASA JPL for space environments with predetermined connectivity schedules, such as Interplanetary communications and LEO satellite systems. The first enhancement, CGR-ETO, aims improve the accuracy of predicted bundle delivery time considering available information on queueing delay. second, Overbooking Management, proactively handle contact...

An EHF satellite system for land-mobile applications to be integrated with a terrestrial cellular is described. approach evaluate the carrier-to-cochannel interference occurring in multispot coverage adopting frequency reuse introduced, and results from analysis are shown. Criteria spectrum efficiency evaluation also outlined along traffic link budget estimates. Possible options payload implementation mobile terminal design presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...

Routing in Delay-/Disruption-Tolerant Networking (DTN) has long been recognized as a challenging research topic. The difficulty lies the fact that link intermittency and network partitioning, possibly coupled with delays, prevent use of Internet solutions based on an up-to-date comprehensive knowledge topology, communicated by routing protocols. In literature DTN routing, there is dichotomy between designed for deterministic (e.g., space flight) networks, such Contact Graph (CGR), wide...

Abstract Designing efficient transmission mechanisms for advanced satellite networks is a demanding task, requiring the definition and implementation of protocols architectures well suited to this challenging environment. In particular, transport performance over impaired by characteristics radio link, specifically long propagation delay possible presence segment losses due physical channel errors. The level impact on depends upon link design (type constellation, margin, coding modulation)...

Internet communications with paths that include satellite link face some peculiar challenges, due to the presence of a long propagation wireless channel. In this paper, we propose Performance Enhancing Proxy (PEP) solution, called PEPsal, which is, best authors' knowledge, first open source TCP splitting solution for GNU/Linux operating systems. PEPsal improves performance connection over channel making use Hybla, enhancement networks developed by authors. The objective paper is present and...

Summary In this paper, we analyze the performance of two contact graph routing (CGR) enhancements, namely, CGR with earliest transmission opportunity (CGR‐ETO) and overbooking management. CGR‐ETO aims to improve accuracy predicted bundle delivery time by exploiting existing information on queueing delay, in decisions. Overbooking management proactively handle oversubscription, which occurs when high‐priority bundles are forwarded a that is already fully subscribed lower‐priority bundles....

This paper deals with the analysis of code-acquisition process performed by a mobile terminal in code-division multiple-access cellular system. The fundamental contribution is setting theoretical framework for analysis, accounting presence fading and shadowing specified coherence time. A multidwell architecture considered, different verification strategies. MAX/TC detection criterion used, acquisition performance analyzed, following both direct flow-graph approaches. Expressions time...

This paper applies the theoretical framework for evaluation of code acquisition in presence fading developed companion Part I paper. Code synchronization code-division multiple-access (CDMA) cellular networks, such as IS-95 and cdma2000, is considered. A multidwell testing procedure adopted. Notably, a optimization parameters (number dwells, dwell lengths, thresholds) to achieve minimum time introduced enforced. The effects fading, interchip interference (ICI), frequency offset,...

Satellite communications are essential to provide Internet access wide areas, helping bridge the "digital divide". However, long RTTs and possible presence of losses due satellite channel errors, severely impair standard TCP performance. To overcome this problem several approaches possible, including adoption enhanced versions TCP. This paper focuses on these, by presenting results a comparative performance evaluation carried out in environment through Linux testbed. The interest analysis...

The capabilities of modern FPGAs permit the mapping increasingly complex applications into reconfigurable hardware. High-level synthesis (HLS) promises a significant shortening FPGA design cycle by raising abstraction level entry to high-level languages such as C/C++. Applications using dynamic, pointer-based data structures and dynamic memory allocation, however, remain difficult implement well, yet constructs are widely used in software. Automated optimizations that aim leverage increased...

“Challenged n etworks” often violate the TCP design key assumption of continuous path availability from source to sink node. These networks are preferred target Delay/Disruption Tolerant Networking (DTN), which aims at providing a more robust network architecture. Against disruptions, however, even standard offers certain level robustness, through its many retransmission algorithms. This intrinsic resilience against disruptions is retained and enhanced if inserted in DTN Focusing on this,...

Although Delay-/Disruption- Tolerant Networking, which originated from research on an Interplanetary Internet, has enlarged its scope to encompass all challenged networks, space applications are still one of most important application fields. This paper deals with DTN communication Moon Earth, based the use a lunar satellite acting as "data-mule" collect data Lander located far side Moon. To make scenario more interesting and complex point view possible security threats, we assume that must...

Interplanetary networks are affected by long propagation delays, intermittent connectivity, possible packet losses due to residual errors, and other impairments. To cope with these challenges, the delay-/disruption-tolerant networking (DTN) architecture utilizes Licklider transmission protocol (LTP) as convergence layer on space links. The LTP reliable service (red) relies Automatic Repeat reQuest, but very delays make forward error correcting (PL-FEC) codes appealing protect segments from...

Delay-/Disruption- Tolerant Networking (DTN) was first conceived to cope with the impairments of Inter-Planetary Internet. Then its scope enlarged cover all "challenged networks", where long delays, disruption, link intermittency and other challenges prevent, or make difficult, use ordinary Internet architecture. To assess DTN performance in such heterogeneous scenarios as space communications (including both satellite deep space) wireless sensor networks, it is essential develop suitable...

Summary The Delay‐/Disruption‐Tolerant Networking (DTN) architecture was designed to cope with challenges such as long delays and intermittent connectivity. To exploit the a priori knowledge of contacts, typical space networks, NASA‐JPL included in ION (its DTN protocol suite) Contact Graph Routing (CGR) algorithm. This paper studies latest version, recently standardized Schedule‐Aware Bundle (SABR) within Consultative Committee for Space Data Systems (CCSDS). first part is devoted algorithm...