An enhanced TCP congestion avoidance scheme and its performance evaluation in high speed satellite networks

High speed satellite communication networks are emerging as part of the future global wireless communication systems. However, existing transmission control protocols for satellite networks do not provide satisfactory performance over high speed satellite links due to their inefficient congestion avoidance algorithms. This paper identifies the reason for low throughput of a widely used protocol Space Communications Protocol Specification (SCPS) in such networks and proposes a new Transmission Control Protocol (TCP) congestion avoidance algorithm to overcome the drawback of the congestion avoidance algorithm used in the SCPS protocol. Numerical results through simulations demonstrate that the proposed new algorithm can achieve significant throughput improvement over links with variable error rates, compared with its legacy counterpart

A Model-based Scalable Reliable Multicast Transport Protocol for Satellite Networks

In this paper, we design a new scalable reliable multicast transport protocol for satellite networks (RMT). This paper is the extensions of paper in [18]. The proposed protocol does not require inspection and/or interception of packets at intermediate nodes. The protocol would not require any modification of satellites, which could be bent pipe satellites or onboard processing satellites. The proposed protocol is divided in 2 parts: error control part and congestion control part. In error control part, we intend to solve feedback implosion and improve scalability by using a new hybrid of ARQ (Auto Repeat Request) and adaptive forward error correction (AFEC). The AFEC algorithm adapts proactive redundancy levels following the number of receivers and average packet loss rate. This leads to a number of transmissions and the number of feedback signals are virtually independent of the number of receivers. Therefore, wireless link utilization used by the proposed protocol is virtually independent of the number of multicast receivers. In congestion control part, the proposed protocol employs a new window-based congestion control scheme, which is optimized for satellite networks. To be fair to the other traffics, the congestion control mimics congestion control in the wellknown Transmission Control Protocol (TCP) which relies on “packet conservation” principle. To reduce feedback implosion, only a few receivers, ACKers, are selected to report the receiving status. In addition, in order to avoid “drop-to-zero” problem, we use a new simple wireless loss filter algorithm. This loss filter algorithm significantly reduces the probability of the congestion window size to be unnecessarily reduced because of common wireless losses. Furthermore, to improve achievable throughput, we employ slow start threshold adaptation based on estimated bandwidth. The congestion control also deals with variations in network conditions by dynamically electing ACKers

P-XCP: A transport layer protocol for satellite IP networks

Explicit Control Protocol (XCP) is a promising transport layer protocol for satellite IP networks. Nevertheless, two problems of XCP are identified in this paper, namely, low throughput under high link error rate conditions, and output link underutilization in the presence of rate-limited connections. To address the first problem, we propose to maintain the transmission rate of an XCP sender when triple duplicate ACK is detected. To solve the second problem, we propose to adjust the aggregated feedback based on the ratio of the number of rate-limited connections to the total number of connections sharing the link. We then combine our proposed solutions to form a new protocol, called P-XCP. Simulation results show that P-XCP overcomes the two problems of XCP. When packet error rate is over 0.1, P-XCP is shown to enjoy a throughput almost double that of XCP. © 2004 IEEE.published_or_final_versio

Transport layer protocols and architectures for satellite networks

Designing efficient transmission mechanisms for advanced satellite networks is a demanding task, requiring the definition and the implementation of protocols and architectures well suited to this challenging environment. In particular, transport protocols performance over satellite networks is impaired by the characteristics of the satellite radio link, specifically by the long propagation delay and the possible presence of segment losses due to physical channel errors. The level of impact on performance depends upon the link design (type of constellation, link margin, coding and modulation) and operational conditions (link obstructions, terminal mobility, weather conditions, etc.). To address these critical aspects a number of possible solutions have been presented in the literature, ranging from limited modifications of standard protocols (e.g. TCP, transmission control protocol) to completely alternative protocol and network architectures. However, despite the great number of different proposals (or perhaps also because of it), the general framework appears quite fragmented and there is a compelling need of an integration of the research competences and efforts. This is actually the intent of the transport protocols research line within the European SatNEx (Satellite Network of Excellence) project. Stemming from the authors' work on this project, this paper aims to provide the reader with an updated overview of all the possible approaches that can be pursued to overcome the limitations of current transport protocols and architectures, when applied to satellite communications. In the paper the possible solutions are classified in the following categories: optimization of TCP interactions with lower layers, TCP enhancements, performance enhancement proxies (PEP) and delay tolerant networks (DTN). Advantages and disadvantages of the different approaches, as well as their interactions, are investigated and discussed, taking into account performance improvement, complexity, and compliance to the standard semantics. From this analysis, it emerges that DTN architectures could integrate some of the most efficient solutions from the other categories, by inserting them in a new rigorous framework. These innovative architectures therefore may represent a promising solution for solving some of the important problems posed at the transport layer by satellite networks, at least in a medium-to-long-term perspective. Copyright (c) 2006 John Wiley & Sons, Ltd

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

Evaluation of Network Mobility Schemes for Terrestrial and Satellite Networks

NEtwork MObility (NEMO) supports the mobility of multiple Internet-connected devices. However, NEMO Basic Support Protocol suffers from unoptimized route leading to large latency in communication and header overhead. To optimize route, a plethora of schemes have been proposed. These schemes differ in terms of several performance parameters, such as signaling, end-to-end delay andhandoff latency. However, no performance or cost evaluation exists in the literature to compare the schemes. In addition, mobility management is required to support the mobility of Internet-connected devices in satellite networks. Existing mobility management solutions for satellite networks are unable toprovide connectivity to the Internet when satellites are not directly connected to the ground.In this dissertation, a comprehensive evaluation of the schemes and a mobility management solution for satellite networks using NEMO are provided. The schemes are classified and compared to choose the optimal class. Using analytical and simulation-based models, the schemes in the chosen class are compared based on the performance parameters. The effect of the parameters on transmission Control Protocol, the dominant transport protocol in the Internet, is also evaluated. A cost evaluation is performed to determine the network resource consumption of the schemes. Finally, an architecture and extensions of the basic protocol are presented to apply NEMO in satellite networks. This dissertation fosters the application of NEMO to terrestrial and satellitenetworks by selecting and extending optimal route optimization schemes, and presenting new architecture and protocol

Analysis of TCP Performance over a Low-Delay MAC Protocol Designed for Satellite-based Sensor Networks

Advances in terrestrial network technology such as fibre optic cables have significantly increased data rates and reduced cost, making it highly attractive for high-speed data networks. However, satellite communication remains competitive for certain applications where it has clear advantages over other technologies including fibre optic cables. The point to multipoint broadcast capability of a satellite is an important characteristic that allows multiple sub-networks or nodes to be controlled simultaneously by a single transmission. Similarly, multiple sub-networks or nodes can send data to a central point through a common channel, instead of using multiple point-to-point channels. This facilitates implementation of unique supervisory control and data acquisition systems such as a sensor network to monitor oil and gas pipelines or for agricultural purposes. One important problem in design of a satellite data network is how uncoordinated sources can share the common satellite channel. A multiple access control protocol is required to achieve efficient sharing of the channel while meeting the user traffic constraints. This paper investigates effects TCP performance when used with a new low-delay protocol that integrates Random Access and Bandwidth-on-Demand techniques

Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks

Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is having strong resemblance to terrestrial GSM (Global System for Mobile communications) at the upper protocol layers and TCP (Transmission Control Protocol) is one of them. This space segment technology as well as terrestrial technology, is characterized by periodic variations in communication properties and coverage causing the termination of ongoing call as connections of Mobile Nodes (MN) alter stochastically. Although provisions are made to provide efficient communication infrastructure this hybrid space and terrestrial networks must ensure the end-to-end network performance so that MN can move seamlessly among these networks. However from connectivity point of view current TCP performance has not been engineered for mobility events in multi-radio MN. Traditionally, TCP has applied a set of congestion control algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery) to probe the currently available bandwidth on the connection path. These algorithms need several round-trip times to find the correct transmission rate (i.e. congestion window), and adapt to sudden changes connectivity due to handover. While there are protocols to maintain the connection continuity on mobility events, such as Mobile IP (MIP) and Host Identity Protocol (HIP), TCP performance engineering has had less attention. TCP is implemented as a separate component in an operating system, and is therefore often unaware of the mobility events or the nature of multi-radios' communication. This paper aims to improve TCP communication performance in Mobile satellite and terrestrial networks.Comment: 5 pages, 2 figure