On performance of group key distribution techniques when applied to IPTV services

Technological evolution is leading telecommunications toward all-IP scenarios, where multiple services are transported as IP packets. Among these services is the broadcast of video. A possible mechanism for broadcasting multiple video channels over IP is to use IP multicast, and let each client decide about the reception of a channel. The secure IP multicast specified by the IETF MSEC working group is a candidate solution for securing these broadcast services. In this paper we propose a new solution for supporting the broadcast of multiple video channels which can be accessed only by authorized users; besides, when a video channel is not visualized in the last mile its transmission is temporarily suspended, so that the cable can be used for other services such as standard Internet access.

Offering new multicast services supporting quality of service becomes essential for an Internet service provider at the worldwide level. The "IP multicast" technology is stable, but scalability of "quality of service multicast" is further from being solved, since scalability problems appear with the increasing number of concurrently active multicast groups. In this paper, we propose a framework that offers quality of service enabled multicast. We start with discussing the drawbacks of quality of service policies that are currently adopted by service providers, and point out their real needs from a multicast view point. In our approach, a service provider will propose an independent class of service dedicated to multicast applications. We describe the properties of this "dedicated class of service", and associate "admission control" mechanisms. We discuss the advantages of our approach, based on multicast extensions and adaptations of Diffserv model. Implementation issues are also presented in an MPLS environment. We conclude, through a case study, that it is possible to dedicate a class of service for multicast traffic.

Network operators have been reluctant to deploy IP multicast services mainly due to the lack of native control over multicast groups. This lack of control does not only prevent operators from generating revenue from multicast-based services but also hinders regular network management. In this work we identified the network elements where admission control should be enforced for multicast sessions spawning over heterogeneous access networks. The architecture proposed uses existing AAA functionality to perform user identification and multicast session admission control. This control is made at the network layer with no protocol modifications. Three access networks were considered: xDSL, WiMAX and UMTS.

Group communication facilitates efficient data transmission to numerous receivers by reducing data replication efforts both at the sender and in the network. Group communication is used in today’s communication networks in many ways, such as broadcasting in cellular networks, IP multicast on the network layer, or as application layer multicast. Despite many efforts in providing data origin authentication for specific application areas in group communication, no efficient and secure all-purpose solution has been proposed so far.

Allocating resources for multimedia traffic flows with real-time performance requirements is an important challenge for future packet networks. However, in large-scale networks, individually managing each traffic flow on each of its traversed routers has fundamental scalability limitations, in both the control plane's requirements for signaling, state management, and admission control, and the data plane's requirements for per-flow scheduling mechanisms. In this paper, we develop a scalable architecture and algorithm for quality-of-service management termed egress admission control. In our approach, resource management and admission control are performed only at egress routers, without any coordination among backbone nodes or per-flow management. Our key technique is to develop a framework for admission control under a general "black box" model, which allows for cross traffic that cannot be directly measured, and scheduling policies that may be ill-described across many network nodes. By monitoring and controlling egress routers' class-based arrival and service envelopes, we show how network services can be provisioned via scalable control at the network edge. We illustrate the performance of our approach with a set of simulation experiments using highly bursty traffic flows and find that despite our use of distributed admission control, our approach is able to accurately control the system's admissible region under a wide range of conditions.

Building on the success of unicast IP, IP Multicast adopted a simple, open, best-effort delivery model with many-to-many semantics. Despite several years of effort, a general, scalable and reliable end-to-end transport protocol analogous to TCP has proven elusive. Proposed solutions are either inflexible, or incur high control overhead. We present Lightweight Multicast Services (LMS), which enhance the IP Multicast model with simple forwarding services to facilitate scalable and efficient (compared to pure end-to-end) solutions to problems such as reliable multicast. In LMS, routers tag and steer control packets to preselected endpoints and perform fine-grain multicast to guide responses to a subset of the group without transport-level processing. LMS divides error control into transport and forwarding components, which allows the former to remain at the end-points while the latter is pushed to the routers, where it can be implemented very efficiently. The division is clean, resulting in significant gains in performance and scalability, while reducing application complexity. LMS reaches beyond reliable multicast to applications such as scalable collect, any-cast, and in general, any application that can benefit from a hierarchy congruent with the underlying topology.

With the popular adaptation of e-learning in many universities, lectures are sometimes distributed online in the form of real-time streaming videos. In these videos, contents on the chalkboard develop into the main sources of study materials for the students. However, they are usually compressed to minimize the bitrate for on-line streaming, and the process blurs the contents on the chalkboard, making them barely readable. Thus, the usefulness of the video channel is being questioned. To improve the quality of video, we enhance the chalkboard contents of the lecture videos by using foreground/background separation and combination technique. The separation allows foreground content to be normalized and de-noised, thus enhancing the readability of the chalkboard texts. The overall technique emphasizes the chalkboard contents while preserving the integrity of the natural video frame. It thus renders the video channel as an important source of information in providing the students with a beneficial e-learning material.

Many multicast applications, including audio and video, require quality of service (QoS) guarantees from the network. Hence, multicast admission control and resource reservation procedures will be needed. In this paper we present a general framework for admission control and resource reservation for multicast sessions. Within this framework, efficient and practical algorithms that aim to efficiently utilize network resources are developed. The problem of admission control is decomposed into several subproblems that include: the division of end-to-end QoS requirements into local QoS requirements, the mapping of local QoS requirements into resource requirements, and the reclaiming of the resources allocated in excess. These are solved independently of each other yielding a set of mechanisms and policies that can be used to provide admission control and resource reservation for multicast connection establishment. The resource allocation algorithms we consider specifically accommodate receiver heterogeneity (in both end-to-end and per-hop QoS requirements) by reserving necessary and sufficient resources for a multicast session. An application of these algorithms in the context of packetized voice multicast connections over the Mbone is provided to illustrate their applicability.

The complementary characteristics of wireless cellular networks and wireless local area networks (WLANs) make them suitable to jointly offer seamless wireless access services to mobile users. In an integrated cellular/WLAN system, the quality-of-service (QoS) requirements for different services (e.g., voice, real-time video) require admission control to limit the number of connections in each access network. In this paper, we first develop an analytical model to facilitate the evaluation of different admission control policies in a multiservice integrated cellular/WLAN system. We then formulate two different revenue-maximization problems. Each problem takes different QoS requirements into account. By solving the equivalent cost-minimization problems, we evaluate the system performance when different combinations of cutoff priority and fractional guard channel admission control policies are being used. Results show that using a cutoff priority policy in both wireless access networks can achieve the optimal solution for the two optimization problems under a wide range of network conditions.

After a decade of research and development, IP multicast has still not been deployed widely in the global Internet due to many open technical issues: lack of admission control, poorly scaled with large number of groups, and requiring substantial infrastructure modifications. To provide the benefits of IP multicast without requiring direct router support of the presence of a physical broadcast medium, various application level multicast (ALM) models have been attempted. However, there are still several problems with ALM: unnecessary coupling between an application and its multicasting supports, bottleneck problem at network access links and considerable processing power required at the end nodes to support ALM mechanisms. This paper proposes an architecture to address these problems by delegating application-multicasting support mechanisms to smart edge devices associated with the application end nodes. The architecture gives rise to an interesting edge device any-casting technology that lies between the IP-multicasting and the application layer multicasting and enjoys the benefits of both. Furthermore, the architecture may provide sufficient cost-benefit for adoption by service providers. The paper presents initial results obtained from the implementation of a video streaming application over the testbed that implements the proposed architecture.

The use of compression has allowed transmission systems to carry multiple digital audio and video channels, which has fostered complex systems for delivery of programs to the customer. These systems need to be monitored to ensure quality of service using simple control methods within the facility. This is achieved by using test equipment that is networked together to provide monitoring stations. A two-tier approach is used for the testing: First, determination of observable picture defects within the program needs to be calculated by the system to ensure picture quality. Second, protocol analysis is used to verify conformance of the syntax to the standard in order to ensure correct decoding of the picture. This paper discusses how such systems can be implemented within a digital television system.

IP multicast plays a very important role in group communication. At the network level IP multicast provides an efficient one-to-many IP packets delivery but without providing any reliability guarantees. Desirable features of reliable multicast include low end-to-end delay, high throughput and scalability. Active networks open a new perspective in providing more efficient solutions to the problems of reliability. However, the existing active reliable multicast protocols are based on receiver-initiated approach for loss recovery. In this paper we propose a new active reliable multicast protocol by combining sender- initiated and receiver-initiated approaches for loss recovery. This approach helps to solve the scalability problems like acknowledgement implosion, recovery load balancing etc.

12 Terrestrial 1550 nm WDM free-space optical communication systems have been demonstrated to provide a viable means to transport data, voice and video channels for point-to-point applications without the use of optical fiber. Key features of free-space optical transmission systems are their ability to utilize present day telecommunication components such as: laser diode transmitters, high-power optical amplifiers operating within the 1550 nm optical transmission window and high-sensitivity optical receivers designed for multi-Giga- bit data rates. In this paper, we report on details of the world's first field test, demonstrating real time video transmission of eight uncompressed standard-definition (SD) video channels operating at an aggregate data rate of 1.485 Gb/s over a 0.89 km terrestrial free-space link. This data link was used in support of the 2000 Olympic games held recently in Sydney, Australia. Results from this eight- channel SD terrestrial free-space laser communications systems are presented. The transmission system operated error-free continuously from September 14, 2000 until October 1, 2000, twenty-four hours a day, throughout the coverage of the games. Modeling results predict that free- space SD video transmission systems can be designed and operated over significant link distances under nominal visibility conditions.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Multicast admission control in differentiated services network is an important but shortly researched subject. We propose a parameter-based admission control method. The method rejects new multicast join requests that would otherwise decrease the quality experienced by the existing receivers. DiffServ network edge nodes filter join requests and generate new requests. The proposed method is developed as an extension to the DSMCast protocol but could also be adapted to other protocols. In this paper the parameter-based admission control is compared to earlier created, measurement-based admission control methods, as well to situation when no admission control is used.

In this paper, we study the admission and bandwidth allocation problems in real-time video streaming in a cellular network. Admission control in a cellular network is a complex issue due to the mobility of the clients, and the additional workload imposed by incoming clients could exceed the network capacity of a cell and seriously degrade the quality of services provided to the resident clients. To minimize the number of forced terminations of real-time video playback, we incorporate the notion of buffered bandwidth in the admission test for handoff client. Using this approach, we can balance the video workload among adjacent cells to minimize the impact of overloading as the result of handoff operations. We also examine techniques to maintain fairness in services especially under overload situations even though the requested videos from various types of clients could generate very different workload. Simulation experiments confirm the effectiveness of our approach compared to widely used schemes.