Performance analysis of wireless systems in telemedicine - Hybrid network for telemedicine with satellite and terrestrial wireless links

Telemedicine services represent a valuable opportunity to provide medical assistance ensuring high flexibility and prompt set up and to significantly reduce costs. The use of hybrid networks based on satellites and terrestrial wireless systems can be extremely advantageous in terms of flexibility, capillarity and integration with modem medical equipment, in particular representing a suitable solution in case of disasters. In the paper such an architecture is described and key performance for some reference applications, evaluated through simulation, are shown and discussed

Interoperability between WiMAX and broadband mobile space networks

In several countries manufacturers, operators, and public authorities look at WiMAX system as a viable technology to fill the "digital divide," providing broadband services mainly in suburban and rural areas, but also in densely populated areas. Nevertheless, as a standalone system it will never offer global services, and to complement its capabilities, the utilization of broadband space-based access shared among users represents a scalable and cost-effective solution to offer wider area coverage, improved performance in terms of QoS, service continuity in case of terrestrial network failure, and long-range user mobility. Integration between WiMAX and a space-based infrastructure, composed of a combination of satellites and high altitude platforms, can be pursued in several ways. The simplest solution is based on connecting a WiMAX network by means of a terrestrial network terminating at a hub station connected to the space infrastructure. A more flexible solution should allow the WiMAX subscriber station or base station to directly access the space infrastructure. This article addresses the identification of suitable scenarios and a feasibility analysis presenting link budget results related to a subset of the identified solutions

Performance evaluation of TCP-based applications over DVB-RCS DAMA schemes

Transmission Control Protocol (TCP) performance over Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) standard is greatly affected by the total delay, which is mainly clue to two components, propagation delay and access delay. Both are significant because they are dependent oil the long propagation path of the satellite link. I-lie former is intrinsic and due to radio wave propagation over the satellite channel for both TCP packets and acknowledgements. It is regulated by the control loop that governs TCP. The latter is due to the control loop that governs the demand assignment Multiple access (DAMA) signalling exchange between satellite terminals and the network control center. necessary to manage return link resources. DAMA is adopted in DVB-RCS standard to achieve flexible and efficient use of the shared resources. Therefore, performance of TCP over DVB-RCS may degrade due to the exploitation of two nested control loops also depending oil both file selected DAMA algorithm and the traffic profile. This paper analyses the impact of basic DAMA implementation oil TCP-based applications over a DVB-RCS link for a large Set Of study Cases. To provide a detailed overview of TCP performance in DVB-RCS environment, the analysis includes both theoretical approach and simulation campaign. Copyright (C) 2009 John Wiley & Sons, Ltd

CAC-TCP cross-layer interaction in a HAPS-satellite integrated scenario

The integration of a satellite system with a HAPS segment appears very suitable to provide communication services, including Internet access, for a large set of applications. In fact, the-satellite capability to provide wide coverage and broadband access can be enhanced by the use of cost-effective, mobile/portable and low-power consuming user terminals, when HAPS acts as an intermediate repeater. Moreover, also TCP-based applications, which suffer from long latency introduced by the satellite link and in general by errors, can get benefits in terms of end-to-end performance. In this frame, this paper deals with the introduction, on board the HAPS, of an efficient CAC scheme in order to guarantee an optimal utilization of the precious radio resources. In particular, we propose an innovative TCP driven CAC algorithm, which shall take into account not only the QoS requirements, but also TCP statistics obtained through a proxy installed on the HAPS. Results show that the overall system performance in terms of both average throughput and blocking probability is significantly improved

Cross-layer architecture for a satellite-Wi-Fi efficient handover

To achieve fully mobile communications, considering different environments and modern service requirements, a multiple-segment architecture is the most suitable to guarantee service continuity with acceptable performance. Handover (HO) procedures can be invoked either out of necessity (if the current network connection is going off) or to improve performance (if different bandwidth or quality of service is required). In this scenario, to provide uninterrupted communication services, efficient intersegment HO capability must be implemented. The architecture considered includes a satellite segment and a number of Wi-Fi hot spots. A mobile node (MN) can switch from a segment to other exploiting services of mobile Internet protocol (MIP). This architecture introduces great flexibility and ensures capillary coverage; it also strongly affects Transmission Control Protocol (TCP)-based application performance. To efficiently face HO consequences, particularly when the TCP runs as a transport protocol, an innovative protocol architecture based on cross-layer (CL) exchange of information is proposed. Analyses of TCP dynamics during HOs and the performance improvement introduced with the proposed CL architecture, evaluated through the network simulator Ns-2, are presented

Joint DAMA-TCP protocol optimization through multiple cross layer interactions in DVB RCS scenario

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 now 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

Performance Evaluation of a Satellite Communication-based MEC architecture for IoT applications

New scenarios and use cases are raising following the birth of the fifth generation of mobile communications. The Internet of Things (IoT) is one of the main use cases which are growing, leading to a massive amount of data that need to be exchanged throughout the Internet. Satellite communication networks are essential in remote and isolated environments and can support fully connected environments by offloading the terrestrial infrastructure concerning delay–tolerant traffic flows. However, satellite network resources are limited and expensive, so they need to be carefully used in order to avoid waste and satisfy the required user performance. The multi-access edge computing (MEC) concept can be exploited in this context to allow data preprocessing at the edge, i.e., close to the users, so reducing the amount of data that has to traverse the backhaul satellite link and, in some cases, reducing data delivery times. This article analyses the performance of a satellite architecture in the IoT framework highlighting the advantages brought by MEC, also including data aggregation and compression techniques

A cross-layer architecture for satellite network security: CL-IPsec

Cross-layer architectures (CLAs) are proposed to improve performance in networks where physical layer impairments are unpredictable and provision of security services may be challenging, as in satellite networks. This paper proposes an extension to the IPsec protocol, named Cross-Layer IPsec (CL-IPsec), able to provide authentication and integrity services through a cross-layer architecture when the adopted protocol is UDP-Lite. This is suitable for multicast applications that are cost-effectively provided by satellite systems. A satellite emulation platform has been used to validate the CL-IPsec implementation and to evaluate the performance improvement derived from the proposed CLA. © 2008 IEEE

Network layer security: Design for a cross layer architecture

Traditional modular layering schemes have served a major part in the development of a variety of protocols. However, as the physical layer impairments become more unpredictable, a cross layer design (CLD) which is dynamic in nature provides better performance. CLD introduces new challenges in protocol design as well as in the area of security. Using numerical analysis, we show that a link layer design employing header compression and cross layer signalling to protect protocol headers can limit packet discarding. This paper also reviews the IPsec protocol and describes how IPsec can be modified for cross layer architecture. © 2007 IEEE