Mobile TV as a Web Application Mobile Web 2.0 - a new application framework for interactive Mobile TV PER-ERIK SVENSSON KTH Information and Communication Technology Master of Science Thesis Stockholm, Sweden 2007 COS/CCS 2007-21 Mobile TV as a Web Application Mobile Web 2.0 - a new application framework for interactive Mobile TV PER-ERIK SVENSSON Master’s Thesis at KTH ICT/COS and Ericsson Research Academic supervisor and examiner: Professor Gerald Q. Maguire Jr. Company supervisor: Stefan Andersson, Ericsson Research Abstract The existing advanced web browsers in today’s mobile phones open up the door for mobile web applications. By using standard web technologies, a web page can be crafted to mimic the behavior of a normal application. The purpose of this master’s thesis has been to look at web application development for mobile phones in general and to implement a web-based Mobile TV client to determine whether it would be a viable alternative to existing clients based on other technologies. The advantages are the same as for any other web application: 1) the user avoids the hassle of installing an application and will always run the latest version, 2) developers benefit from the browser’s ability to render generic content, and 3) it is believed that the differences between browser implementations are less than in other environments in which an application would run, for example Java or operating system specific environments. ii Sammanfattning Mobil-TV som Webbapplikation De avancerade webbläsare som redan idag finns tillgängliga på nyare mobiltelefoner har gjort det möjligt att skapa mobila webbapplikationer. Genom användandet av befintlig webbteknik kan en webbsida utformas på ett sådant sätt att den uppträder som en vanlig applikation. Syftet med det här examensarbetet har varit att titta på webbutveckling för mobiltelefoner i allmänhet samt att implementera en webbaserad MobilTV-klient för att avgöra hurivida en sådan lösning skulle kunna utgöra ett alternativ till redan existerande klienter baserade på andra teknologier. Fördelarna antas vara desamma som för andra webbapplika- tioner: 1) användaren slipper installera ett program och kommer alltid att köra den senaste versionen, 2) utvecklingen gynnas av webbläsarens förmåga att rendera godtyckligt innehåll och 3) skillnaderna mellan olika webbläsarimplementationer anses vara mindre i jämförelse med andra miljöer i vilka en applikation körs, till exempel Java- eller operativsystemspecifika. iii Acknowledgements First of all, I would like to thank Professor Gerald Q. Maguire Jr. for agreeing on being the examiner and academic supervisor of this thesis and for the valuable comments and corrections, carried out with the broad knowledge and patience that is to be expected from him. Further, I would like to thank everyone at Ericsson giving me important feedback, most notably Stefan Andersson, Clinton Priddle, and Torbjörn Einarsson. Cristian Norlin provided me with the graphical user interface design and much of the graphics, for which I am grateful. iv Contents 1 Introduction 1 1.1 Mobile TV . 1 1.1.1 Mobile TV in cellular networks . 2 1.1.2 Broadcast Mobile TV . 3 2 Mobile web development 4 2.1 HTML . 4 2.2 Cascading Style Sheets . 4 2.3 JavaScript . 5 2.4 Data exchange formats . 6 2.4.1 XML . 6 2.4.2 JSON . 6 2.5 SVG.................................... 7 2.6 Flash . 7 2.7 XHTML . 7 2.8 HTML5 . 8 2.9 WAP.................................... 8 3 Mobile web browsers 9 3.1 Netfront . 9 3.2 Opera Mobile . 12 3.3 Nokia web browser . 13 3.4 Others . 13 3.4.1 Minimo . 13 3.4.2 Pocket Internet Explorer . 14 4 Implementation 15 4.1 Background . 15 4.2 Graphical User Interface . 16 4.3 User input control . 25 4.4 Client-server communication . 26 4.5 Interactivity . 28 5 Evaluation 30 v 5.1 Functionality . 30 5.2 Performance . 31 6 Conclusions and future work 33 Bibliography 35 vi Chapter 1 Introduction Today the Internet is synonymous with the Web for a lot of people. Applications that were previously downloaded or bought as hard-copies and installed natively, are being replaced with web-based alternatives with similar or better functionality. One of the best examples of this is perhaps web-based email clients, where many users depend solely on these services for their email and have been doing so for years. Some of these users have never used any other interface to access, manage and send email. As web browsers have improved, the possibilities have vastly improved for web developers to create services that look and behave much like their desktop counterparts. A driving force for the service providers has been the advantage of having advertising-financed applications, as advertisements on the web are generally more accepted than intrusive adware programs. Web browsers for mobile phones have just recently improved but are still lagging in functionality in comparison with desktop browsers, in part because of the limitations of the phones themselves. However, this is rapidly changing and there are already retail phones available that are equipped with browsers suitable for web application development. This first part of this thesis examines the aspects of web development in general, focusing specifically on mobile phone browsers, with the specific goal of the implementation of a Mobile TV client in mind. The second part describes such an implementation, followed by an evaluation and comparison to Mobile TV clients based on other technologies. 1.1 Mobile TV Mobile TV is believed to be the most successful 3G service with, as early as 2004, a 50% adoption rate in South Korea and an expected adoption rate of 10% for 2007 in Western Europe [1]. But, as noted by Carlsson and Walden, the success of Mobile TV will eventually depend on the content provided being attractive enough to retain a large user base [2]. 1 CHAPTER 1. INTRODUCTION The term Mobile TV is used to describe almost anything that involves the reception and playback of video content on a mobile device. The various technologies used can be categorized into three different groups. The first is unicast streaming, which is the only technology today that is commercially available on a large scale. Unicast streaming Mobile TV involves streaming of video content over existing cellular networks to handheld devices using a separate stream for each device. Another approach to Mobile TV is that of using the existing radio network to stream content to several devices at the same time in a multicast fashion, maintaining a single stream for each channel. A technology for this is Multimedia Broadcast Multicast Service (MBMS), which will be available to the general public in 2008. The third group consists of different, but similar, technologies for broadcasting Mobile TV using a separate radio network specially designed for TV broadcasting to portable devices. We will consider each of the technologies for Mobile TV used in cellular networks and broadcast networks in a section of its own. 1.1.1 Mobile TV in cellular networks Unicast streaming Traditionally, Mobile TV has been delivered via unicast streaming to a Real Time Streaming Protocol (RTSP) -capable player built in to the mobile phone. Usually, the links to the content are provided by the operator on a web (or WAP) portal. The next generation of Mobile TV for receiving unicast streaming consists of J2ME applications specially designed for this purpose. They usually offer added value in the form of Electronic Program Guides (EPGs) and interactivity such as voting, chatting, etcetera. The downside of this approach is that users need to download and install the program as well as any subsequent updates. Because of Java’s security model the application also needs to be cryptographically signed and the user has to give his approval of the certificate and grant or deny the application access to the Internet. MBMS Multimedia Broadcast Multicast Service (MBMS) is an extension of existing third generation (3G) radio networks to be able to broadcast from a single point to multiple receivers via multicast. In contrast to technologies such as DVB-H and T-DMB, an uplink channel will be readily available. There are currently ongoing MBMS trials and the technology will be available to the general public as soon as operators have upgraded their base stations and MBMS capable handsets have been rolled out. This is expected to happen in 2008. MBMS is standardized within the 3rd Generation Partnership Project (3GPP). 2 CHAPTER 1. INTRODUCTION 1.1.2 Broadcast Mobile TV DVB-H, T-DMB, and MediaFlo There are three main competing methods of delivering Mobile TV by means of broadcasting over a separate radio network [3], in a similar fashion that ordinary digital TV is broadcast. In fact, the Digital Video Broadcasting, Handheld (DVB-H) standard is based on the commonly used DVB-T (T for Terrestrial) standard used to provide homes all over the world with digital television. DVB-H has been standardized by the European Telecommunications Standards Institute (ETSI) and it is being pushed by several companies, especially Nokia. Since it uses a separate radio network, operators need to acquire new licenses to operate in that spectrum or to partner with those who do have such licenses. In addition to telecom operators, many others are interested in broadcasting Mobile TV, which could lead to a battle for the few licenses that will be handed out. The regulations differ from country to country. In some countries it may not be possible for a telecommunications operator to acquire such a license. The closest competitor to DVB-H is Terrestrial Digital Multimedia Broadcast (T-DMB) based on Digital Audio Broadcasting (DAB) radio and developed by a group of South Korean companies. The spectrum license regulations may be even harder for T-DMB, for example in the UK 80% of the DAB spectrum has to be used for audio broadcasting [4].