Multi-hop networks have gained a lot of interest in recent years. A lot of work was contributed in the field of protocol design and performance of multi-hop networks. It is generally accepted that mobility has a huge impact on the... more
Multi-hop networks have gained a lot of interest in recent years. A lot of work was contributed in the field of protocol design and performance of multi-hop networks. It is generally accepted that mobility has a huge impact on the protocol performance; even more for multi-hop networks. Obtaining realistic measurements of mobility, however, is complex and expensive. Thus, we adopt virtual world scenarios to explore the mobility issue, by using the well-known multi-player game, Quake II. The advantage of the Quake II engine is that ...
Abstract—The Visualization Tool for Ad Hoc Networks—ViTAN is a tool for visualizing the connectivities and link qualities (capacities) between the terminals in wireless ad hoc networks. The ViTAN tool takes the location of the wireless... more
Abstract—The Visualization Tool for Ad Hoc Networks—ViTAN is a tool for visualizing the connectivities and link qualities (capacities) between the terminals in wireless ad hoc networks. The ViTAN tool takes the location of the wireless terminals (specified by Cartesian coordinates) and the link qualities between the terminals as input. The tool produces a visualization of the graph of the terminals' connectivities in the fig format, which in turn can be converted to any common graphic format. ViTAN does not evaluate the connectivities ...
Google has recently released the video compression format VP8 to the open source community. This new compression format competes against the existing H. 264 video standard developed by the ITU-T Video Coding Experts Group (VCEG) in... more
Google has recently released the video compression format VP8 to the open source community. This new compression format competes against the existing H. 264 video standard developed by the ITU-T Video Coding Experts Group (VCEG) in collaboration with the ISO/IEC Moving Picture Experts Group (MPEG). This paper compares these two video coding standards in terms of video bit rate-distortion (quality) performance and the video network traffic variability with different long video sequences. We find that VP8 presently ...
The wireless market is widely believed to be the most important future market for data services. Despite the efforts that were made to increase usability and abilities of all different wireless devices, the wireless protocol domain is... more
The wireless market is widely believed to be the most important future market for data services. Despite the efforts that were made to increase usability and abilities of all different wireless devices, the wireless protocol domain is still challenging. As new services and protocols emerge for wired networks, the need to incorporate those services and protocols in wireless communication systems arises. Existing wireless networks of the second generation (also known as 2G) are mostly circuit–switched and have been developed and ...
In this report we introduce the VideoMeter, a tool developed for the comparative evaluation of the quality of raw video data in the YUV format. The tool gives the differences in PSNR quality between two or three YUV video sequences and... more
In this report we introduce the VideoMeter, a tool developed for the comparative evaluation of the quality of raw video data in the YUV format. The tool gives the differences in PSNR quality between two or three YUV video sequences and includes also a player for YUV video streams. In a typical application scenario, the tool is used for the quality assessment of videos that have been encoded with some lossy compression scheme and transported over a lossy network. The tool can be used to simultaneously play (i) the original YUV video ...
H. 26L is currently in the development status and is due to become standard according to the ITU–T and ISO/MPEG groups in late 2002. It will then become part of the H. 2xx, H. 3xx and MPEG standard families. H. 26L is expected to replace... more
H. 26L is currently in the development status and is due to become standard according to the ITU–T and ISO/MPEG groups in late 2002. It will then become part of the H. 2xx, H. 3xx and MPEG standard families. H. 26L is expected to replace its predecessors H. 261 and H. 263, which were widely used in integrated circuits for telephone and video equipment for ISDN services over telephone networks. H. 26L has been designed with packet-switched networks in mind and has in its current implementation a complete network adaptation ...
Network security and authentication are very important for all kinds of communication networks to assure network stability and to avoid subscription fraud. In the last years–even for wireless local area networks–mechanisms have been found... more
Network security and authentication are very important for all kinds of communication networks to assure network stability and to avoid subscription fraud. In the last years–even for wireless local area networks–mechanisms have been found to support both in a cellular network. In multi–hop networks based on IEEE802. 11, security and authentication are still open issues. Mainly the low price of the network infrastructure makes this kind of networks vulnerable. Within the scope of this paper we describe the ...
Currently available video traces for scalable encoded video with more than one layer are a convenient representation of the encoded video for the evaluation of networking mechanisms. The video distortion (RMSE) or quality (PSNR) for... more
Currently available video traces for scalable encoded video with more than one layer are a convenient representation of the encoded video for the evaluation of networking mechanisms. The video distortion (RMSE) or quality (PSNR) for individual video frames in these traces, however, only allow for the calculation of the video quality of correctly received video frames; for lossy network transport, only a rough approximation can be made. With the availability of scalable offset distortion traces, which we introduce and evaluate in this ...
In this paper we outline our future research activities in the area of wireless multi–hop communication systems. Our focus is on the link level design issues for IP based multi–hop communication systems using code division multiple access... more
In this paper we outline our future research activities in the area of wireless multi–hop communication systems. Our focus is on the link level design issues for IP based multi–hop communication systems using code division multiple access with pseudo–noise spreading sequences. We employ pseudo noise sequences to keep the signalling overhead low. In particular, we report on our initial design considerations and evaluations of a low complexity power control mechanism for multi–hop CDMA systems. Our Interference ...
