Past, present and future of IP telephony

“Copyright © [2008] IEEE. Reprinted from International Conference on Communication Theory, Reliability, and Quality of Service, 2008. CTRQ '08. ISBN:978-0-7695-3190-8. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”Since the late 90's IP telephony, commonly referred to as Voice over IP (VoIP), has been presented as a revolution on communications enabling the possibility to converge historically separated voice and data networks, reducing costs, and integrating voice, data and video on applications. This paper presents a study over the standard VoIP protocols H.323, Session Initiation Protocol (SIP), Media Gateway Control Protocol (MGCP), and H.248/Megaco. Given the fact that H.323 and SIP are more widespread than the others, we focus our study on them. For each of these protocols we describe and discuss its main capabilities, architecture, stack protocol, and characteristics. We also briefly point their technical limitations. Furthermore, we present the Advanced Multimedia System (AMS) project, a new system that aims to operate on Next Generation Networks (NGN) taking the advantage of its features, and it is viewed as the successor to H.323 and SIP

Internet protocol over wireless sensor networks, from myth to reality

Internet Protocol (IP) is a standard network layer protocol of the Internet architecture, allowing communication among heterogeneous networks. For a given network to be accessible from the Internet it must have a router that complies with this protocol. Wireless sensor networks have many smart sensing nodes with computational, communication and sensing capabilities. Such smart sensors cooperate to gather relevant data and present it to the user. The connection of sensor networks and the Internet has been realized using gateway or proxy- based approaches. Historically, several routing protocols were specifically created, discarding IP. However, recent research, prototypes and even implementation tools show that it is possible to combine the advantages of IP access with sensor networks challenges, with a major contribution from the 6LoWPAN Working Group. This paper presents the advantages and challenges of IP on sensor networks, surveys the state-of-art with some implementation examples, and points further research topics in this area

A first approach towards pervasive computing using current tools: a real example

The paper presents the real implementation of a system that empowers the traveling professional through the use of current tools and mobile platforms. A book selling system was developed and deployed in a server together with Pocket PC 2003 enabled PDA systems. The global vision of such systems is given and the current implementation is also presented

PSCoP: planning scheduler coprocessor

The use of a centralised planning scheduler in fieldbus- based systems requiring real-time operation has proved to be a good compromise between operational flexibility and timeliness guarantees. In this paper a preliminary implementation of a hardware scheduling coprocessor based in the planning paradigm is presented. The coprocessor is installed in a special node of the fieldbus, the bus arbiter, and generates scheduling tables to be dispatched by the node CPU. With this solution it is possible to decrease the response time to changes in the system configuration or message parameters of the software-based planning scheduler. This opens the possibility of allowing automatic on-line changes requested by system nodes in addition to the ones requested by human operators, thus improving system reactivity. In this paper the focus is on the coprocessor’s interface with the node CPU and its overall functionality. Initial calculations showing the feasibility of the unit and its expected performance are also derived

User-centric plug-and-play functionality for IPv6-enabled wireless sensor networks

“Copyright © [2010] IEEE. Reprinted from 2010 IEEE International Conference on Communications. ISBN:978-1-4244-6402-9. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”Smart nodes that sense the environment and communicate wirelessly to reach a sink node create wireless sensor networks. One of the main research challenges regarding wireless sensor networks is user deployment, namely in terms of configuration and management. On non-commercial solutions the user typically must be aware of the underlying technology to obtain sensing services. Internet connectivity is also desirable, so future deployments must take into consideration this feature, enabling realistic ubiquitous computing. This paper presents a user-centric solution for IPv6-enabled wireless sensor networks, using the Contiki operating system and Crossbow TelosB motes, featuring a Plug-and-Play like experience. One of the motes provides sink node capability to the network, through USB connection with a personal computer, which sends and receives data, presenting it to the user. A dedicated serial protocol for USB communication with the sink was developed and extensively debugged, featuring sink querying and network configuration. The current testbed uses User Datagram Protocol over IPv6, with 6LoWPAN, and IEEE 802.15.4 wireless communication between the sensor network motes and the sink device. A Plug-and-Play like operation is achieved through zero-user configuration, since the user only needs to plug in the sink and give power to the remote motes

Web service based multi-channel application

The paper presents an application using a purpose-created web service that is consumed in a multi-channel environment. The service clients span over the common web interface, a JAVA-enabled GSM 2.5G mobile phone, and a Microsoft® Windows® application. The web service provides basic message passing functionality

Accept mobile: a mobile tool for the SINMETRO accept information system

Increasing demand of mobile applications for on-site data acquisition pushes the development of flexible and easy to use mobile tools, with great advantages over the traditional computer-based approaches. The Accept System from SINMETRO allows data gathering for quality control, in the form of Inspection sheets. Such tool allows quality assurance by monitoring some samples of a given material, for instance milk, wine, and even maintenance management. This paper presents a mobile application in the Accept System that allows a Personal Digital Assistant (PDA) device to perform data gathering based on XML Inspection templates. Using .NET Compact Framework through C#, and database the technologies SQL Server and SQL Server CE, we developed Accept Mobile. Accept Mobile uses the Remote Data Access (RDA) mechanism to send data over to the server through a synchronization service, while also providing the needed support for disconnected operation. We prove that the mobile application is very convenient and provides enough functionality for the user to dismiss the portable computer, although the main application was never developed with mobility concerns in mind

Using a hardware coprocessor for message scheduling in fieldbus-based distributed systems

“Copyright © [2001] IEEE. Reprinted from 8th IEEE International Conference on Electronics, Circuits and Systems. ISBN:0-7803-7057-0. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”Fieldbus based distributed embedded systems used in real-time applications tend to be inflexible in what concerns changing operational parameters on-line. Recent techniques such as the planning scheduler can avoid this problem but do not show adequate responsiveness f o r automatic negotiation of parameter values. In this paper the use of ASIC based coprocessors f o r message scheduling is proposed to solve the problem. Such coprocessors can be used in the arbiter nodes of systems based on widely used producer-consumer fieldbuses like WorldFIP and CAN. A prototype built with a Xilinx FPGA is presented. First performance results are shown and analyzed. They demonstrate that the device is able to achieve the expected performance and also point to the possibility of evolution to an almost dynamic scheduling approach

Flexible time-triggered protocol for CAN: new scheduling and dispatching solutions

One of the possibilities to build robust communication systems with respect to their temporal behaviour is to use autonomous control based on the time-triggered paradigm. The FTT-CAN - flexible time-triggered protocol, relies on centralised scheduling but makes use of the CAN native distributed arbitration to reduce communication overhead. There, a planning scheduler is used within a master node to reduce the scheduling run-time overhead. On-line changes to the communication requirements can then be made under guaranteed timeliness. In addition FTT-CAN also allows an efficient combination of both time-triggered and event- triggered traffic with temporal isolation. In this paper, recent evolutions of the initial protocol definition concerning transmission of synchronous and asynchronous messages are presented. These consist in a time division of the elementary transmission window which optimises the available bandwidth for asynchronous messages, keeping the timeliness of synchronous messages without jeopardising their transmission jitter. A novel solution for the planning scheduler is also presented. It consists in an FPGA-based coprocessor which implements the planning scheduler technique without imposing overhead to the arbiter CPU. With it, it is possible to reduce strongly the plan duration thus allowing on-line admission demanded by system elements and, also, to extend the protocol application to high-speed networks

A biosensor and data presentation solution for body sensor networks

A Body Sensor Network can sense health parameters directly on the patient’s body, allowing 24/7 monitoring in an unobtrusive way. Several tiny sensors collect and route data to a special sink node. A new intra-vaginal biosensor was developed to study the relation between temperature variations and women health conditions, such as ovulation period, among others. We present a biosensor prototype and some initial results on real scenarios with a woman. One of the main issues in a body sensor network is the transformation of the sensor raw data into meaningful medical data for medical staff. Several approaches exist, from mobile device-based approaches to more powerful hardware such as a personal computer. This paper presents our current work in body sensor networks, namely a prototype for intra-vaginal temperature monitoring with initial results, and a mobile tool for data presentation of a three-tier body sensor network. The gathered results demonstrate the feasibility of the approach, contributing to the widespread application of body sensor networks