Cross-Layer Management of Radio Resources in an Interactive DVB-RCS-Based Satellite Network—(Invited Paper) (original) (raw)
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IEEE Personal Communications, 2001
he recent evolution of the Internet and the spread of networked multimedia applications have highlighted the need to investigate the techniques, tools, and device configurations to guarantee a certain level of quality of service (QoS) to end users. The characteristics of the network used are extremely important to get to the aim. Some types of networks, such as asynchronous transfer mode (ATM), were designed to support QoS for specific traffic flows. A statistic investigation to verify the availability of the resources to guarantee a fixed level of service is performed before accepting a new call entering the network. A call admission control (CAC) mechanism is used in this case. On the other hand, the Internet is a "best-effort" network (TCP/IP protocols were not designed to provide guaranteed QoS), and it only does its best. It is characterized by heterogeneity from the points of view of both algorithms and management, and physical links. There are high-speed channels, low-speed phone links, wireless multi-access channels, and satellite portions. Moreover, many organizations and providers manage the Internet. In the meanwhile, its development has been incremental, and the number of services and applications are growing more and more.
Dynamic resource allocation based on a TCP-MAC cross-layer approach for DVB-RCS satellite networks
International Journal of Satellite Communications and Networking, 2006
Satellite communication networks can provide multimedia broadband services to fixed and mobile users in several scenarios where terrestrial networks are not present or where they need to be complemented. Moreover, satellite links can be useful to bypass crowded terrestrial networks, thus helping in reducing congestion. In such a scenario, characterized by a high propagation delay and a radio channel affected by losses, standard bandwidth allocation schemes prove to be inefficient when Transmission Control Protocol (TCP) is running. Hence, we propose a novel resource allocation scheme based on the cross-layer interaction between TCP and Medium Access Control (MAC) layers. The interest is here in achieving an efficient transfer of files by means of the FTP application protocol. Our scheme permits to avoid network congestion, to reduce the average file transfer time and to achieve a fair sharing of resources among competing flows. The allocation technique has been applied to an Interactive Satellite Network (ISN) based on the DVB-RCS standard with a group of fixed satellite terminals, which communicate with a Network Control Center (NCC) through a geostationary bent-pipe satellite, according to a classical star topology. Results are obtained through a network simulator.
2005
DVB-RCS is an open standard for interactive broadband satellite services. According to the standard, interactive terminals communicate with the network control center through the return channel adopting MF-TDMA. In this scenario, classical bandwidth allocation schemes do not take into account TCP evolution, leading to sub-optimal performance when TCP-based traffic share the return link. A cross-layer approach, based on exchange of information between not-adjacent layers, can help to improve efficiency. This paper presents an innovative allocation algorithm based on a cross-layer interaction between TCP and MAC layers. Such an algorithm aims to synchronize the requests of resources with the TCP transmission window trend. The obtained results show that our scheme permits both to reduce the delay, to increase the utilization of air interface resource and to achieve a fair share of resources among competing flows
Transport Protocol and Resource Management for Satellite Networks: Framework of a Project
The paper describes the protocol definition within the framework of the Project "Transport Protocol and Resource Management for Mobile Satellite Networks", funded by the European Space Agency ESA) and carried out by an Italian group composed of Marconi Mobile, CNIT and Etnoteam. In more detail, the Project is aimed at designing, implementing and testing a protocol stack adapted to the specific characteristics of a satellite communications system. The protocol stack is based on the TCP/IP suite adapted to the channel characteristics. The objective is the optimization of both the transport protocol performance for a satellite network environment and the efficient utilization of network resources. This has been achieved without re-designing the protocol interfaces, so that they will keep the same characteristics of the interfaces currently used. These characteristics should get the target of maximizing the system performance and, in the same time, allow the utilization of sta...
Multimedia Satellite Networks and TCP/IP Traffic Transport
International Journal of Computers and Applications, 2001
To meet an increasing demand for multimedia services and electronic connectivity across the world, satellite networks will play an indispensable role in the deployment of global networks. A number of satellite communication systems have been proposed using geosynchronous (GEO) satellites, medium earth orbit (MEO) and low earth orbit (LEO) constellations operating in the Ka-band and above. At these frequencies satellite networks are able to provide broadband services requiring wider bandwidth than the current services at C or Ku-band. Most of the next generation broadband satellite systems will use ATM or "ATM like" switching with onboard processing to provide full two-way services to and from earth stations. The new services gaining momentum include mobile services, private intranets and high data rate internet access carried over integrated satellite-fiber networks. Several performance issues need to be addressed before a transport layer protocol, like TCP can satisfactorily work over satellite ATM for large delay-bandwidth networks. In this paper, we review the proposed satellite systems and discuss challenges such as, traffic management and QoS requirements for broadband satellite ATM networks. The performance results of TCP enhancements for Unspecified Bit Rate over ATM (ATM-UBR+) for large bandwidth-delay environments with various end system policies and drop policies for several buffer sizes are presented.
Advanced transport satellite protocol
2012 IEEE Global Communications Conference (GLOBECOM), 2012
Mitigation of Transmission Control Protocol (TCP) performance degradation over satellite has been extensively studied over the last two decades by the scientific community, which has come up with a large set of protocol and architecture solutions. This paper proposes a novel end-to-end (E2E) transport layer protocol, namely Advanced Transport Satellite Protocol (ATSP), which is built around consolidated control theory concepts already infused in Active Queue Management (AQM) control schemes. ATSP exploits the knowledge of the bandwidth allocated to each terminal, as available from the satellite network operator. Besides, the satellite network property of being completely under control allows the joint collaboration of sender, receiver and routers in order to acquire a complete knowledge of the network status and eventually optimize the overall performance. The performance analysis shows that ATSP achieves a fair bandwidth share for all the satellite users and outperforms TCP Hybla, which is optimized for satellite links, in terms of throughput.
TCP congestion control in shared satellite environments
MILCOM 2002. Proceedings
This paper describes the use of a transparent TCP gateway to improve the performance of applications operating in a shared secure satellite environment. Typically, a satellite gateway is installed at each end of the satellite link, and the gateways process all traffic traversing the link. With the proliferation of virtual private network (VPN) technologies, multiple encrypted tunnels can be established over a satellite link. If transparent TCP gateways are used to optimize application performance, a pair of gateways are required at the egress points of each tunnel. Many TCP gateways perform poorly in this situation because they do not implement congestion control on their 'satellite' sides, instead relying mainly on rate-control to send data at or near the bandwidth capacity of the satellite link Our approach is to use Space Communications Protocol Standards (SCPS) transparent transport layer gateways, which are capable of implementing a variety of congestion control schemes on their terrestrial and satellite sides. By using a variant of the TCP Vegas congestion control algorithm, the gateways can communicate indirectly (by detecting changes in packet round-trip times) to efficiently share the satellite bandwidth. Results show that this improves performance over end-to-end TCP without congesting the network between the gateways and the uplink as pure rate-control would do.
Implementation and Evaluation of TCP Enhancements over Satellite Links
2006
Internet over satellite is an emerging facet of communications enabling users to have access to the Internet over high speed satellite links. However, new requirements should be satisfied by the involved protocols in order to fully utilize the available network resources. This paper discusses the possible mitigations that can be applied to the Transmission Control Protocol over satellite links. Furthermore, we study the performance of the TCP enhancements we implemented in a simulated satellite environment.
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.