Thorsten Lohmar

Delivery of Broadcast Services in 3G Networks

TV is regarded as a key service for mobile devices. In the past, Mobile TV was often associated with broadcast transmission. However, unicast technology is sufficient in many cases, especially since mobile users prefer to access content on-demand, rather than following a fixed schedule. In this paper we will focus on 3G mobile networks, which have been primarily optimized for unicast services. Based on a traffic model we will discuss the capacity limits of 3G networks for unicast distribution of Mobile TV. From the results it can be concluded that the capacity is sufficient for many scenarios. In order to address scenarios in which broadcast is a more appropriate technology, 3GPP has defined a broadcast extension, called Multimedia Broadcast Multicast Service (MBMS). MBMS introduces shared radio broadcast bearers and has thus the capabilities of a real broadcasting technology. We will give a short overview about MBMS including a discussion on MBMS capacity. Since MBMS is primarily a new transport technology, additional application and service layer technologies are required, like electronic service guide and service protection. These mechanisms are standardized by the Open Mobile Alliance (OMA) and are favorably combined with MBMS or 3G unicast distribution in order to create complete end-to-end solutions. In order to optimize a system for delivery of broadcast services over 3G networks, the advantages of broadcast and unicast should be combined. We argue that hybrid unicast-broadcast delivery offers the best system resource usage and also the best user experience, and is thus favorable not only for broadcast delivery in 3G networks, but actually also for non-cellular broadcast systems like DVB-H or DMB

Dynamic adaptive HTTP streaming of live content

MPEG has recently released a first public draft of the new Dynamic Adaptive Streaming over HTTP (DASH) specification. The new streaming technique is based on the 3GPP and partly also on the Open IPTV Forum (OIPF) specifications. In this paper, we give an overview about the new DASH specification with a special focus on Live streaming services. In order to re-use existing web content distribution schemes, the new streaming technique provides the live stream as a sequence of files, which are continuously downloaded by the streaming client. This way of streaming introduces new delay components into the system streaming. Live Streaming technology is often used for events like sport events to allow other users to virtually participate. It is generally preferred to minimize the end-to-end delay for live services. In the paper, we identify and analyze the different delay components of the new adaptive HTTP streaming technique and how they contribute to the end-to-end delay of live services. We also discuss the dependencies and system implications when minimizing the end to end delay. The evaluation principles are also applicable for other adaptive HTTP streaming formats.

Convergence of cellular and broadcast networks from a multi-radio perspective

The demand of both the new telecom industry and digital broadcasters for cost-efficient provisioning of mobile multimedia services faces the reality of scarce radio resources. Various digital mobile and broadcast radio technologies have been developed and specifically been optimized. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real time, and multicast communication. This article describes an evolution of an IP-based infrastructure from todays networks toward a future multi-radio infrastructure, taking into account the implications on the end-user terminal. This multi-radio infrastructure enables the cooperation of existing radio networks to combine their spectrum-efficient capabilities, whereby high-quality mobile multimedia services shall be provided. Furthermore, the need for dynamic allocation of spectrum to radio services is motivated. The basic functionality and architecture of a multi-radio system are outlined, with a special emphasis on cooperation between different radio systems. Also, an evolution path for the convergence of broadcast and new telecom is described, starting from todays systems and leading to a fully coordinated system.

MBMS—IP Multicast/Broadcast in 3G Networks

In this article, the Multimedia Broadcast and Multicast Service (MBMS) as standardized in 3GPP is presented. With MBMS, multicast and broadcast capabilities are introduced into cellular networks. After an introduction into MBMS technology, MBMS radio bearer realizations are presented. Different MBMS bearer services like broadcast mode, enhanced broadcast mode and multicast mode are discussed. Streaming and download services over MBMS are presented and supported media codecs are listed. Service layer components as defined in Open Mobile Alliance (OMA) are introduced. For a Mobile TV use case capacity improvements achieved by MBMS are shown. Finally, evolution of MBMS as part of 3GPP standardization is presented.

3GPP Mobile Multimedia Streaming Standards [Standards in a Nutshell]

Data rates offered by mobile networks are increasing, as are the capabilities of mobile devices. With this, mobile multimedia services are getting wider distribution. Traditional linear mobile TV services, where the viewer has to watch a scheduled TV program at the offered time, were initially dominating but other streaming services like Video on Demand, User-Generated Content (USG) services, or Internet streaming services are becoming more important. This article describes the 3rd Generation Partnership Project (3GPP) standards for mobile unicast multimedia streaming and how they are used in almost 200 mobile networks.

Performance evaluation of a file repair procedure based on a combination of MBMS and unicast bearers

With the booming of multimedia services, the 3rd generation partnership project (3GPP) has introduced the multimedia multicast/broadcast service (MBMS) feature for UMTS systems. The main objective of MBMS is to introduce real broadcast distribution capabilities into 3G systems. The MBMS service layer toolbox supports two distinct delivery methods: download and streaming. This paper focuses on the MBMS download delivery method. We have a particular focus on the file repair procedure, because the distribution of binary data via MBMS must result in 100% transmission error free downloaded files. In order to achieve this goal, MBMS offers a forward error correction (FEC) mechanism to protect the actual MBMS transmission and an extra file repair procedure to be used after the actual MBMS transmission. This paper discusses the trade-off between FEC protection and successive file repair, and then proposed a novel file repair scheme. The new scheme combines point-to-multipoint (PTM) file repair transmission with a point-to-point (PTP) file repair procedure. Using only a point-to-multipoint file repair scheme is not efficient, since the sender does not know the amount of needed repair data. Our simulations and analysis show that the new scheme achieves better performance than a PTP-only file repair procedure. Further, the two schemes are compared with respect to the radio resource consumption

Flow-control for multi-access systems

Future wireless communication systems will be characterised by an integration of different access technologies. Such systems will feature a user-friendly coordination of the complementary access technologies to access personalized services in a seamless manner via the currently most suitable access. Efficient resource management will provide cost effective bandwidth. These systems need a flow-control functionality to select always the best suitable access system for a certain traffic flow in different environments. This paper lists requirements and describes a flow control functionality that controls the forwarding of individual traffic flows over different access systems in a multi-access scenario. In addition, examples are presented and discussed as to how this advanced multimedia flow-control can be embedded both in a co-operative and in an integrated multi-access system architecture, providing thereby guidelines for standardization and future products.

Radio resource optimization for MBMS File transmissions

The 3GPP Multimedia Broadcast and Multicast Service (MBMS) for mobile networks enables the efficient distribution of files to a large audience using point-to-multipoint transmission. MBMS provides the so called file delivery service for this purpose. Residual errors are not tolerable in the received data of the file. Application Layer Forward Error Correction (AL-FEC) and transmit power need to be configured to yield low residual errors after the initial file transmission. In order to recover also the residual packet errors a repair phase is executed in which terminals can request additional AL-FEC encoded packets. The paper assumes repair packets are transmitted using HSDPA and evaluates the overall system efficiency, balancing ALFEC, transmit power, packet size and the amount of missing data that has to be retransmitted in the repair phase.

Convergence of Broadcast and New Telecom Networks

The demand of the new telecom industry for cost efficient provision of mobile multimedia services is faced with the reality of scarce radio resources. The requirement of spectrum efficiency has driven the development of various digital radio technologies that have been optimized for specific services, namely for broadcast or for mobile communication. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real-time, and multicast communication. This paper describes an IP based multi-radio infrastructure that enables the co-operation of existing radio networks to combine their capabilities to ensure a spectrum efficient provision of high-quality mobile multimedia services. Further the need for a dynamic allocation of spectrum to radio services is motivated. The basic functionality and the architecture of a multi-radio system is outlined, with a special emphasis on the cooperation between different radio systems. Further an evolution path for the convergence of broadcast and new telecom is desribed, starting from todays systems and leading to a fully coordinated system.

Support of Multicast Services in 3GPP

ABSTRACT In line with the growing interest in efficient data distribution services to large mobile user groups, 3GPP is standardizing the introduction of support for multicast services into GSM and WCDMA networks. The mobile infrastructure needs to be enhanced in the wireless and in the wireline parts to support new signaling and payload transport procedures. Also mobility, charging and radio resource handling aspects have to be considered. Starting from group distribution services and their requirements, this paper motivates and describes the solutions defined and discussed within 3GPP, namely the introduction of new nodes, new bearers and new procedures to efficiently support multicast services.