Gábor Fehér

Performance evaluation framework for IP resource reservation signalling

This paper investigates the scalability limitations of signalling-based Quality of Service (QoS) provisioning using the RSVP and Boomerang protocols as examples. We establish a performance evaluation framework, which contains per hop metrics for describing the routers signalling capability and per reservation metrics for characterising the overall performance of the reservation protocol. The per hop metrics are captured in a simple router model, using parameters that are based on actual measurements. This router model is used in a simulation scenario, which characterises the end-to-end impact and overall performance of the RSVP and Boomerang reservation protocols.This paper summarises the results of router benchmarking measurements and simulations. The per session results highlight that, with thorough selection of the control protocol, signalling-based resource reservation is a realistic approach in the Internet. It is also shown that the selection of the signalling protocol can seriously influence the reservation performance of a router and thus the overall performance of the entire network as well. The presented performance evaluation framework can be used for network dimensioning and it can even aid the design of new resource reservation protocols and new router devices.

Benchmarking of Signaling Based Resource Reservation in the Internet

This paper investigates the scalability limitations of IP resource reservation protocols using RSVP and Boomerang as examples. The memory and processing time consumption of signaling message primitives were measured as a function of the total number of concurrent reservation sessions on PC-based routers running Linux and on a commercial router. The signaling handling algorithm of the implementations were analyzed as well and critical operations were identified. Our results show that CPU time is a more significant scalability concern than the router memory and also that the former is very dependent on the implementation and complexity of the signaling algorithm. Thus the same Linux PC can handle Boomerang reservation requests several hundred times faster than RSVP requests.

Robust Wavelet-Based Video Watermarking Using Edge Detection

In this paper a robust video watermarking method is presented, which embeds data in the wavelet domain using edge detection. The algorithm uses the luminance values around the edges where changes are less noticeable for the human visual system. Watermark is embedded in an additive way using spread spectrum noise. The complexity of the method is low. The algorithms used for wavelet transformation and edge detection are fast and simple. Results show that the watermark signal is imperceptible, and the method is robust against low bitrate lossy compressions, like H.264.

Enhancing Progressive Encryption for Scalable Video Streams

The technique called progressive encryption is used in many areas of content security. However, the plain algorithm itself is only applicable in real transmission scenarios where no packet loss occurs, otherwise additional error correction techniques need to be used in order to achieve maximum decodeability of network packets. The cipher-stepping method (CSM) described in this article adds error correction to progressive encryption in the case where stream ciphers are used to encrypt stream data. It is also explained how the CSM method along with progressive encryption can be used in the encryption of scalable video streams.

Enhancing wireless video streaming using lightweight approximate authentication

In this paper, we propose a novel lightweight approximate authentication algorithm that provides efficient protection for wireless video streaming where attacks on the stream are possible, but classical integrity protection algorithms are impractical because bit errors occur naturally. The benefits of the proposed algorithm over other algorithms are fast execution and small message authentication code size. Moreover, the approximate authentication supports error resilient video decoding by dropping seriously damaged packets, thus improving the perceived quality of the video stream. The performance of the algorithm is demonstrated via numerical analysis, simulations and measurements over modeled and real wireless channels.

VLC-Based Indoor Localization

The omnipresence of LEDs for illumination provides unique opportunities for indoor localization. Signals transmitted by the LEDs can be used to determine the position of a person or object within a room with high precision. The requirements of such applications are different from high speed VLC systems. One of the commonly employed methods for VLC-based localization is optical tracking and imaging while the other is based on trilateration/triangulation. However, in both the methods it is critical that the user device is able to recover signals from each luminaire separately. In order to achieve this, a number of processing methods and devices can be chosen, which will be elaborated in this chapter. Practical implications including the required modifications/additions on the illumination infrastructure to enable positioning are also covered.

Visible light communication channel disturbances and examination of the modulation formats

The paper experimentally investigates indoor visible light communication (VLC) channels. The disturbances come from the light bulbs and other VLC systems. The paper demonstrates that the noisiest light bulbs are the fluorescent lamps which emit high frequency disturbances. Different light bulbs are examined to make an optimal carrier choice for the transmitted signal. In the next part of the paper several modulation schemes and two kinds of detector systems are compared. The paper represents also the advantages and disadvantages of receiver constructions with and without a lens. The optimum modulation for different application is investigated.

The Price of Secure Mobile Video Streaming

The cryptographic algorithms providing unquestionable security are usually complex. From this point of view, it is reasonable that high bit rate secure live video streams require significant processing power from the end devices. To cope with the demands, there are many publications suggesting a kind of selective video encryption that reduce the burden by ciphering only a part of the video stream. As a tradeoff, the security level decreases. On the other hand, recently the retail price of the efficient hardware based cryptographic chips is dropped and devices became more and more resourceful. This is true for the mobile sector as well. In this article, based on measurements, we prove that the fully encrypted high bit rate mobile video streaming is a true possibility today, moreover there are certain scenarios where it is advised to be used. The resource barrier is no longer the processing capacity, rather the network link.

Pulsed mode red VCSEL for high speed VLC communication

VCSELs (Vertical-cavity surface-emitting lasers) offer a number of unique advantages: a threshold current that is low and stable with temperature so that electricity is converted to light with a very high efficiency; the ability to be modulated at very high frequencies; a circular output beam with low divergence, simplifying the optical system. Lifetime parameters are not degraded when overdriving its normal operating current in a low duty cycle application. The mentioned properties of VCSELs makes them excellent for usage in high speed free space optical links. However till the end of the last decade 850 nm VCSEL dominated the high speed area. Because of the laser safety regulations, the power limits restricted the 850 nm VCSEL usage in free space optical links. The fabrication problems of visible light producing VCSEL has been solved recently, and high speed 650 nm (red) VCSELs are available on market. In this paper we will show how a pulsed mode laser driver can exploit the unique properties of VCSELs in low cost, low power and high speed visible light communication (VLC) links.

Optimisation of multimedia over wireless IP links via X-layer design: an end-to-end transmission chain simulator

End-to-end optimised Quality of Service (QoS) and its specific declination for multimedia applications with the end-user Perceived Quality of Service (PQoS) is a topic that is more and more discussed in the literature. Many different techniques and approaches have been proposed, which are in general focusing on specific weak technical aspects of the transmission chain in the considered scenario. The end-to-end optimisation from a system point of view, i.e., to be transparently integrated in existing legacy systems and not perturbate their operation, is more complex and its practical realisation is yet to be achieved. In this paper, we propose an architecture set-up within the ICT FP7 OPTIMIX project to study innovative solutions enabling enhanced multimedia streaming in a point to multi-point context for an IP based wireless heterogeneous system, based on cross layer adaptation of the whole transmission chain. The corresponding simulation chain architecture is detailed with the description of the existing and/or future features of each module.