Robert R. Chodorek

An analysis of elastic and inelastic traffic in shared link

Nowadays, we observe rapid growth of multimedia transmissions in the Internet. Multimedia are typically carried out using the RTP protocol, while the rest of Internet traffic is transmitted via the TCP protocol. In the paper the problem of coexistence of elastic and inelastic traffic is presented. In contrast to other papers, which analyze this issue as the problem of TCP-unfriendliness of the RTP protocol, we focus on this coexistence from multimedia point of view.

QoE validation of a RSVP protocol extension enabling efficient resource reservation for aggregated traffic in heterogeneous IP networks

In this paper we propose an extension to RSVP protocol, based on dynamic resource reservations, which allows for better coexistence of HD video transmission and elastic traffic (e.g. bulk data transfer). These extensions have been evaluated in two different domains, both in the Quality of Experience (QoE) domain and in the Quality of Service (QoS) domain. Experiments carried out in an emulated multi-node heterogeneous network show that the proposed extensions are profitable, especially in the network domain. They are able to assure a better quality of service for elastic traffic than typical RSVP reservations and offer the same QoS for HD video transmission as well-dimensioned typical RSVP. Analysis in QoE domain confirms that proposed extensions assure a video transmission quality unnoticeably worse than the one possible with RSVP (with no extensions).

Providing QoS for high definition video transmission using IP Traffic Flow Description option

A real-time multimedia transmission requires the QoS guarantees to preserve the real-time character of the stream. Nowadays, we have several methods for QoS provisioning in IP networks. In this paper we propose a novel method for dynamic network resource allocation using the IP Traffic Flow Description option. Our solution deals with the problem of the trade-off between link utilization and the quality of real-time service. We tested the proposed method using the emulation system, which consists of a streaming server, a network emulator and video receivers. As network emulator, the Berkeleys ns-2 simulator (working in emulation mode) was used. The streaming server and the video receiver were built on the base VLC software. The results of the experiment performed in the test environment show that the proposed solution ensures both satisfactory QoS for HD video and good link utilization.

A Linux Kernel Implementation of the Traffic Flow Description Option

The Traffic Flow Description is an option of the IP protocol that allows end-systems to describe generated traffic flows. Such description includes instantaneous values of transmitted data in a given time. The option enables intermediate systems to assure QoS based on dynamic resource allocation. In this paper an implementation of the Traffic Flow Description option for the Linux kernel is presented. The paper includes both the description of the option, proposed by the Author as the Internet Draft working document and detailed description of the prototype implementation of the proposed option in the Linux kernel. The implementation covers both improvements introduced to the current long term stable 4.1.20 version of the Linux kernel and two helper functions that enable the option to be set up easily. Tests show that the functionality of the prototype implementation complies with the specification of the option, given in the Internet Draft. Results of performance tests show that the prototype implementation is able to work as a part of the system of QoS assurance.

Expanding the Ns-2 Emulation Environment with the Use of Flexible Mapping

The Berkeley’s ns-2 simulator was, for a long time, one of the most popular open-source simulation tools. Although the new tool in the ns family, the ns-3, replaced it in the above ranking, the simplicity of the ns-2, with its flexibility and ability to operate at higher levels of abstraction caused the simulator to remain in use. This paper presents our enhancements to the mapping of incoming and outgoing traffic in the ns-2 simulator when it works in emulation mode. Our enhancements expand the build-in 1-to-1 MAC address mapping to 1-to-many address/port mapping, which allows the emulator to connect to more end-systems or subnetworks than the number of interfaces of the emulation server.

ECN-capable TCP-friendly Layered Multicast Multimedia Delivery

ECN-capable TCP-friendly layered multicast mul-timedia delivery combines explicit congestion notifica-tion (ECN) with the TCP-friendly layered multicast scheme. TCP-Friendliness denotes that receiver–driven architecture behaves under congestion like the TCP protocol. Unlike well-known TCP-friendly proto-cols (TFRC, TFMCC, WEBRC), which use TCP throughput the equation, our system assures TCP-friendliness by emulation. The Receiver emulates TCP congestion control mechanism working with ECN con-gestion notification. Decisions about changing group membership and, as a result, about changing effective transmission rate, are taken based on TCP emulation. In the paper, a simulation model of ECN-capable mul-ticast multimedia delivery in ns-2 environment is dis-cussed.

An analysis of the applicability of the TFD IP option for QoS assurance of multiple video streams in a congested network

The Trafïîc Flow Description (TFD) option is an experimental option of the IP protocol, designed by the Authors, able to assure signaling for QoS purposes. The option is used as a carrier of knowledge about forthcoming traffic. If planning horizons are short enough, this knowledge can be used for dynamic bandwidth allocation. In the paper an analysis of QoS assurance using the TFD option is presented The analysis was made for a case of QoS protection of multiple video streams. Results show that dynamic bandwidth allocation using the TFD option gives better QoS-related parameters than the typical approach to QoS assurance, based on the RSVP protocol.

Traffic flow description based on scene change analysis

QoS guarantees for real-time HD video transmission can be assured by proper resource allocation. The TFD option of the IP protocol can be used to convey signaling information about required resources for a given transmission. In this paper the new traffic description for TFD option, based on analysis of scene changes, is presented. The traffic description was carried out in two stages. First, scene changes were detected and second, traffic estimations were performed within separate scenes. The results of experiments show that the proposed solution is able to assure QoS at a satisfactory level.

TFD-capable dynamic QoS assurance using a variable time horizon based on scene changes

The Traffic Flow Description (TFD) is a new option of the IP protocol, designed by the Authors for Quality of Service (QoS) signaling. In contrast to the traditional, long-term, RSVP-based signaling, which is able to serve only static QoS assurance, the TFD option provides signaling on different time horizons, enabling dynamic QoS assurance. The TFD option conveys information about forthcoming traffic (bit rate in a given time horizons), which is taken from analysis of the sending data stream. The option is specified in an IETFs working document (Internet Draft) and was tested for video transmission. Papers about TFD-based reservations, previously published by the Authors, report results of experiments that were carried out using a constant time horizon. This paper discusses the usage of the TFD option for dynamic QoS assurance, where a variable time horizon (based on scene detection and analysis of the frames of the sending movie) was used. Results show that scene analysis can be a useful tool for dynamic QoS assurance.

ECN-capable Multicast Multimedia Delivery

Explicit Congestion Notification (ECN) is a method of signalling intended to inform end-system(s) of congestion in at least one router along delivery path. In IP networks, congestion build-up is usually detected using active queue management (e.g. RED) and clear indication of congestion can be transferred through the network using ECN bit (the CE codepoint in the IP header). In the paper, ECN-capable multicast multimedia delivery is presented. Described system combines ECN-capability with receiver-driven layered transmission. Experiments show that the use of ECN capable transmission allows to avoid the two main disadvantages of layered transmission scheme: lack of fairness and unexpected packet losses in basic layer.