Arne Lie

Evalvid-RA: trace driven simulation of rate adaptive MPEG-4 VBR video

Due to the increasing deployment of conversational real-time applications like VoIP and videoconferencing, the Internet is today facing new challenges. Low end-to-end delay is a vital QoS requirement for these applications, and the best effort Internet architecture does not support this natively. The delay and packet loss statistics are directly coupled to the aggregated traffic characteristics when link utilization is close to saturation. In order to investigate the behavior and quality of such applications under heavy network load, it is therefore necessary to create genuine traffic patterns. Trace files of real compressed video and audio are text files containing the number of bytes per video and audio frame. These can serve as material to construct mathematical traffic models. They can also serve as traffic generators in network simulators since they determine the packet sizes and their time schedule. However, to inspect perceived quality, the compressed binary content is needed to ensure decoding of received media. The EvalVid streaming video tool-set enables this using a sophisticated reassembly engine. Nevertheless, there has been a lack of research solutions for rate adaptive media content. The Internet community fears a congestion collapse if the usage of non-adaptive media content continues to grow. This paper presents a solution named Evalvid-RA for the simulation of true rate adaptive video. The solution generates real rate adaptive MPEG-4 streaming traffic, using the quantizer scale for adjusting the sending rate. A feedback based VBR rate controller is used at simulation time, supporting TFRC and a proprietary congestion control system named P-AQM. Example ns-2 simulations of TFRC and P-AQM demonstrate Evalvid-RA’s capabilities in performing close-to-true rate adaptive codec operation with low complexity to enable the simulation of large networks with many adaptive media sources on a single computer.

Linking Acoustic Communications and Network Performance: Integration and Experimentation of an Underwater Acoustic Network

Underwater acoustic networks (UANs) are an emerging technology for a number of oceanic applications, ranging from oceanographic data collection to surveillance applications. However, their reliable usage in the field is still an open research problem, due to the challenges posed by the oceanic environment. The UAN project, a European-Union-funded initiative, moved along these lines, and it was one of the first cases of successful deployment of a mobile underwater sensor network integrated within a wide-area network, which included above water and underwater sensors. This contribution, together with a description of the underwater network, aims at evaluating the communication performance, and correlating the variation of the acoustic channel to the behavior of the entire network stack. Results are given based on the data collected during the UAN11 (May 2011, Trondheim Fjord area, Norway) sea trial. During the experimental activities, the network was in operation for five continuous days and was composed of up to four Fixed NOdes (FNOs), two autonomous underwater vehicles (AUVs), and one mobile node mounted on the supporting research vessel. Results from the experimentation at sea are reported in terms of channel impulse response (CIR) and signal-to-interference-plus-noise ratio (SINR) as measured by the acoustic modems during the sea tests. The performance of the upper network levels is measured in terms of round trip time (RTT) and probability of packet loss (PL). The analysis shows how the communication performance was dominated by variations in signal-to-noise ratio, and how this impacted the behavior of the whole network. Qualitative explanation of communication performance variations can be accounted, at least in the UAN11 experiment, by standard computation of the CIR and transmission loss estimate.

Underwater acoustic network performance: Results from the UAN11 sea trial

An underwater acoustic network (UAN) represents a communication infrastructure that can offer the necessary flexibility for continuous monitoring and surveillance of critical infrastructures located by the sea. Given the current limitation of acoustic-based communication methods, a robust implementation of UANs is still an open research field. The FP7 UAN project moved along these lines, and it was one of the first cases of successful deployment of a mobile underwater sensor network integrated within a wide-area network, which included above water and underwater sensors. This contribution gives details on the UAN network structure and equipment. It reports statistics on the performance of the system as collected during the project final sea trial, which was held in Trondheim, Norway, in May 2011. The UAN network was in operation for five continuous days and was composed of up to four fixed nodes, two autonomous underwater vehicles and one mobile node mounted on the supporting research vessel. Results from the experimentation at sea are reported in terms of channel impulse response and signal to noise plus interference ratio as measured by the acoustic modems during the sea tests. The performance of the upper network levels are measured in terms of round trip time and probability of packet loss. Finally, the experimental results have been compared with those obtained in simulation using the BELLHOP acoustic code, fed with the environmental data gathered during the sea trial.

Underwater Wireless Sensor Network

The NNN-UTS project (Nordområdenes Nye Nervesystem – Undervanns Trådløst Sensornettverk) has aimed to develop wireless network technology for underwater sensor networks, employing acoustic communication to realize wireless functionality in water. Research and development has been carried out in 2006-2009. A final sea test/demonstration of the system was carried out at Breiangen in the Oslo fjord, on December 3-4 2009. The result is a fully operative network system available for water depths down to 4000m.

Quality of Service, Adaptation, and Security Provisioning in Wireless Patient Monitoring Systems

Modern patient monitoring systems are designed to put the individual into the centre of the system architecture. In this paradigm, the patient is seen as a source of health-relevant data that are processed and transferred. Patient monitoring systems are used in health care enterprises as well as in paramedic, mobile, and home situations to foster ambient assisted living (AAL) scenarios. There are a multitude of standards and products available to support Quality of Service (QoS) and security goals in patient monitoring systems. Yet, an architecture that supports these goals from data aggregation to data transmission and visualisation for end user has not been developed. Medical data from patient monitoring systems includes sampled values from measurements, sound, images, and video. These data often have a time-aspect where several data streams need to be synchronised. Therefore, rendering data from patient monitoring systems can be considered an advanced form of multimedia data. We propose a framework that will fill this QoS and security gap and provide a solution that allows medical personnel better access to data and more mobility to the patients. The framework is based on MPEG-21 and wireless sensor networks. It allows for end-to-end optimisation and presentation of multimedia sensor data. The framework also addresses the QoS, adaptation and security concerns of handling this data. In Section 2 we present background on patient monitoring systems, their requirements and how we envision communication is handled. We present communication systems in Section 3 and how to treat QoS in Section 4. A short introduction to data streaming, binary XML and how they relate to patient monitoring systems is presented in Section 5. In Section 6we our proposed solution for the framework and present a security analysis of it in Section 7. Finally, we offer our conclusions in Section 8. 36

On the use of the MPEG-21 framework in medical wireless sensor networks

This paper proposes a system architecture for wireless sensor network (WSN) using the MPEG-21 multimedia framework in medical applications. It has been envisioned that future hospitals will have networks comprising WSNs for low rate medical sensors as well as other network nodes supporting high rate audiovisual content. The increasing collection and variety of media content (multimedia) in such a scenario, needs a framework for the interaction with the external users regarding data filtering, meta information tagging, authentication and data rights control. Furthermore due to different user terminals and network resources, media adaptation will become important to provide reliable and robust quality of services. The MPEG-21 standard seems to have potential to meet some of the mentioned requirements. In this paper, we argue for an extension of the MPEG-21 terminology for use in biomedical wireless sensor networks and incorporate the requirements needed for medical applications. We show the architecture of a demonstration prototype based on this extended MPEG-21 framework that is under development, capable of displaying selected biomedical sensor data. The deployment of such a system may become warranted in future healthcare enterprises.

Power control in HetNets and cognitive networks

In order to meet the demand for increased capacity in wireless networks, incorporating femtocells within the coverage of macrocells constitutes one of the strategies that currently receives most attention from both industry and academia. Femtocells may either be part of a HetNet as standardised within 3GPP, or constitute the secondary system in cognitive networks. Power control is a useful mechanism to allow efficient communications within both femto- and macrocells, but should be designed differently in the two cases. The performance of two different power control algorithms suitable for 3GPP femtocells and cognitive femtocells, respectively, is considered in this publication.

On the cleansing and inspection of GPS ephemeris data 2000–2016

Archived GPS ephemeris data for years 2000–2016 is investigated by cleansing and precision measures. The goal of this work was twofold: (1) to reveal and remove incorrect ephemeris data so that the cleansed data is as close to the real broadcasted data as possible, and (2) to analyse the quality of the cleansed data by comparing ephemeris based satellite locations to true locations. Our findings show that, besides obvious duplicates, many erroneous data epochs were also detected by monitoring the slowly changing I0 and Ω0 parameters. The cleansed data shows small deviation precision errors steadily decay in the 2000– 2016 period, as expected. Also the number of large errors show a decaying nature. Many large errors occur frequently in first operation period of new satellite vehicles, especially the new Block IIF, but these happened also to show in time epochs close to periods flagged as unhealthy. Further, it is shown that ephemeris data performance is independent on Toe parameter being modulo 100 or not.

Interactive system design and end-to-end optimization in sensor networks

This paper proposes an application oriented four layered quality of service (QoS) stack for wireless sensor networks (WSN), including a supporting system architecture for interacting with WSNs using the MPEG-21 multimedia framework in an medical application setting. The application of the WSNs is signal processing algorithms reporting elaborated observed sensor data to external users. The QoS model supports the tradeoff between end-users expected QoS combined with optimized energy consumption. The MPEG-21 standard is chosen as the media resource framework due to the fact that future hospitals will have networks comprising WSNs supporting an always increasing amount of both low rate medical sensor data as well as high rate audiovisual content. Furthermore due to the heterogeneous set of user terminals and network resources, media adaptation will become important to provide reliable and robust quality of service. In this paper, we argue for an extension of the MPEG-21 terminology for use in biomedical wireless sensor networks and incorporate the requirements needed for medical applications.