Dimensioning and effective handling of signalling channels in a multimedia GEO Satellite platform

The deployment of highly powerful and sophisticated new-generation satellite broadband systems implies that a large portion of their bandwidth on the radio interface has to be devoted to conveying signalling information. Adequately dimensioning such a signalling bandwidth is an important design objective allowing the effective exploitation of the overall system resources and the cost-effective provision of a target quality of service to multimedia traffic. The performance of two basic techniques for accessing the signalling channels in a reference multimedia geostationary platform is investigated in this paper: random (slotted Aloha) and dedicated access. It is demonstrated here that dedicated access, despite rational appearances, allows 50% saving of signalling bandwidth while satisfying both the system and user constraints in terms of grade and quality of service respectively. This is accomplished by providing a statistical centralized connection admission control on Earth and an intelligent scheduling of the resource requests on board the satellite.     

Wireless broadband applications: the teleservice model and adaptiveQoS provisioning

This article presents a teleservice model for wireless broadband applications based on an adaptive QoS paradigm. According to this, a multimedia broadband application is considered as a set of hierarchically ordered adaptable media streams, which accept varying degrees of network-level guarantees, depending on dynamic resource changes and user preferences. Some algorithms that match the proposed paradigm are designed for call and mobility management. Their performance is analyzed in a mobile multitier cellular system, including the satellite component     

Making a mesh router/gateway from a smartphone: Is that a practical solution?

This paper aims at answering the question whether it is practical to build a mesh-phone or not. A mesh-phone is a smartphone acting as a mesh router, i.e. either actively participating in the process of packet forwarding towards a mesh gateway, or acting itself as a gateway toward the Internet. Technical aspects of the mesh-phone implementation, such as design constraints and implementation details, are addressed. The technical feasibility is validated by describing the implementation of a prototype of the mesh-enabled phone over the Openmoko^TM open platform. Besides technical feasibility also convenience of the addressed solution is analyzed in terms of the consumed power, and some “energy-saving” related enhancements are suggested to be applied to future user’s devices.     

Designing the interworking of terrestrial and satellite IP-basednetworks

The design of effective interworking between a multimedia terrestrial backbone and a satellite access platform is a key issue for the development of a large-scale IP system designed for transporting multimedia applications with QoS guarantees. This article focuses on the design of a gateway station that acts as an interworking unit between the two segments of the systems. The guarantee of differentiated QoS for applications within the envisaged global IT system is achieved effectively by assuming that the IP IntServ model in the satellite access system is combined with a DiffServ fixed core network, in which the RSVP aggregation protocol is implemented. Thus, the design activity of the IWU mainly focuses on the following issues: seamless roaming between the two heterogeneous wireless and wired environments, efficient integration between the two IP service models (IntServ and DiffServ), and suitable mapping of terrestrial onto satellite bearer for traffic with different profiles and QoS requirements     

Call management based on the mobile terminal-peak velocity: virtues and limitations in a two-tier cellular system

The aim of the presented research is to study an effective algorithm for the admission control and handoff management of mobile user connections in a realistic urban scenario with a two-tier (micro- and macrocell) cellular coverage. The algorithm behavior is strongly related to the knowledge of the mobility profile of the users. Thus, an analysis of analogous algorithms available in literature and which exploit mobility estimation precedes our design activity. Their advantages and drawbacks have been observed and are used as a starting point for the design of our algorithm. It overcomes the weaknesses that the previous algorithms show when operating in a realistic urban scenario. As a consequence, it reduces the call-blocking probability and minimizes the handoff rate.     

Experimental Missions in W-Band: A Small LEO Satellite Approach

W-band (75-110 GHz) is proposed nowadays as a valuable alternative to intensively-exploited Ku- and Ka-bands for high-speed transmission over satellite networks. In such a framework, some experiments are being carried out, which are targeted to verify the feasibility of exploitation of W-band for broadband service deployment. From a theoretical viewpoint, the large bandwidth availability and the scarce amount of interference typical of W-band should guarantee high capacities. Nevertheless, many crucial aspects are still to be carefully investigated, e.g., signal propagation issues, RF impairments, choice of modulation and coding, efficient antenna design, etc. In this paper, an overview is made on the low Earth orbit (LEO) nano-satellite mission in-orbit key-test and validation of W-band (IKNOW). IKNOW mission is an ongoing advanced feasibility study part of an Italian Space Agency Project, named W-band analysis and verification (WAVE), coordinated by the Department of Electronic Engineering, University of Rome ldquoTor Vergatardquo. The main objective of the IKNOW mission is to tackle some of the unexplored critical aspects concerning W-band satellite transmission. In such a perspective, IKNOW should be regarded as a ldquopilot mission,rdquo whose results will be used for a first uplink-downlink satellite channel characterization, in-orbit validation of W-band technology, and space qualification processes. This paper is focused on the research work carried out in a preliminary phase of the IKNOW study and will also consider a number of elements related to the mission configuration, payload architecture, link analysis, potential RF impairment factors, and atmospheric effects. Proposed analysis and preliminary results shown can provide to interested readers the basic guidelines that will drive the practical implementation of IKNOW mission, as well as the most relevant issues to be faced by future developers of W-band missions using small LEO satellites.     

QoS for multimedia applications in satellite systems

We present a policy for handling multimedia traffic over satellite air interfaces. It extends the advantages of ATM to satellite by the statistical multiplexing of variable-rate traffic sources. Effectiveness is assessed within a multimedia satellite platform called EuroSkyWay, based on Ka-band payload and on-board processing     

D-RMA: a dynamic reservation multiple-access protocol for thirdgeneration cellular systems

A dynamic reservation multiple access (D-RMA) protocol for third generation cellular mobile radio systems is proposed and its behavior is investigated under variable multimedia traffic conditions. D-RMA is a protocol which is explicitly designed to support multimedia traffic. Its structure is based on traditional PRMA++ protocol, but in addition to what PRMA++ provides, it introduces a flexible dynamic approach in the choice of the percentage of bandwidth to be used for reservation. Separation between reservation and information channels, along with dynamic adaptation of the percentage of reservation bandwidth within a frame to traffic condition, guarantee the required QoS to multimedia services. Results obtained show that the performance of D-RMA are superior when compared to a traditional “nondynamic” protocol, in terms of both the offered quality of service (QoS) and number of connections which can be activated in a microcell at one time     

New Concept Platforms for QoS Management in Future Telecommunication Scenarios

In this paper the concept of “Situation&Location” based platforms for QoS management in next-generation heterogeneous telecommunication scenarios is presented. The exploitation of a Multi-Agent System is investigated with the aim of providing a user with seamless and optimized network access to the desired service based on its current situation and location. Key feature of the proposed system is the presence of a middleware platform exploiting user profile-, resource-, and situation-management agents whose ontology is specified in XML language. The proposed platform is intended as a sample architecture for QoS control and adaptation. It tries to contribute to the research activities that several forums, interest groups, and standardization bodies are conducting in the view of 4G system full deployment.     

QoS Guarantees in Heterogeneous Systems Consisting of IP Core Networks with Satellite Access

This paper aims at investigating the issue of differentiated QoS provision to services over a heterogeneous terrestrial-satellite infrastructure. In particular, the implementation of a dynamic mapping of the main service classes offered by IP IntServ and DiffServ models over satellite bearer services is investigated.Objective of the research is to enable mobile subscribers to access broadband services offered within a fixed IP core network, through satellite links. This has to be performed while still guaranteeing the same Quality of Service (QoS) offered by the IP IntServ and DiffServ models over the terrestrial segment. In such an environment, the considered traffics derive from multimedia applications and are characterised by real-time and non-real-time constraints as well as variable (VBR) and constant (CBR) bit-rate profiles.