Research Article DELIVERING MULTIMEDIA CONTENT FOR THE FUTURE GENERATION MOBILE NETWORKS S. Swarna Parvathi, Dr. K. S. Eswarakumar Address for Correspondence S. Swarna Parvathi, PhD Scholar Department of I&C, Anna University, Chennai E Mail swarna@svce.ac.in Dr. K. S. Eswarakumar, Professor& Head, Department of CSE, Anna University, Chennai ABSTRACT The evolution of the mobile broadband network to the Fourth Generation (4G) wireless network will provide for the delivery of high-speed video, voice and data services directly to a cellular handset or handheld Internet device. It is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features. This paper deals with understanding the features and challenges, the proposed architectural frameworks, multimedia support and multiple access schemes for 4G. KEYWORDS: 4G, Streaming, Challenges, Architecture. INTRODUCTION In recent years, there has been a rapidly increasing demand for the development of advanced interactive multimedia applications such as video telephony, video games, and TV broadcasting. However, these applications are always stringently constrained by current wireless system architectures due to the need for high data rates for video transmission. To better serve this need, 4G broadband mobile systems are in planning and are expected to increase the mobile data transmission rates and bring higher spectral efficiency, lower cost per transmitted bit, and increased flexibility of mobile terminals and networks. The new technology strives to eliminate the distinction between video over wireless and video over wire line networks. In the meantime, great opportunities are provided for proposing novel wireless video protocols and applications, and developing advanced video coding and communications systems, and algorithms for the nextgeneration video applications that can take maximum advantage of the 4G wireless systems. At the same time, it is probable that the radio access network will evolve from a centralized architecture to a distributed one. Many portal sites offer streaming audio and
video services for accessing news and entertainment content on the Internet from a PC. The term multimedia streaming means that there are more than one media type involved in communication, e.g. text and graphics, voice, animations, video and audio. We define multimedia to denote the property of handling a variety of representation media in an integrated manner. This means that the various sources of media types are integrated into a single system framework. Currently, three incompatible proprietary solutions offered by Real Networks, Microsoft, and Apple dominate the Internet streaming software market. In the near future, the fourth-generation mobile communication systems will extend the scope of today s Internet streaming solutions by introducing standardized streaming services, targeting the mobile users specific needs. By offering higher datatransmission rates up to 20 Mbps more than 3G for wide-area coverage and local-area coverage, 4G systems will be able to provide high quality streamed content to the rapidly growing mobile market. In addition to higher data rates, these systems also will offer value-added applications supported by an underlying network that combines streaming services with a range of unique mobile specific services such as Multimedia content, geographical positioning, user profiling, and mobile payment. DESIRED FEATURES OF 4G High usability and global roaming: The end user terminals should be compatible with any technology, at any time, anywhere in the world. The basic idea is that the user should be able to take his mobile to any place, for example, from a place that uses CDMA to another place that employs GSM. Multimedia support: The user should be able to receive high data rate multimedia services. This demands higher bandwidth and higher data rate. Personalization: This means that any type of person should be able to access the service. The service providers should be able to provide customized services to different type of users. MAIN CHALLENGES To achieve the desired features listed above researches have to solve some of the main challenges that 4G is facing viz.,
Multimode user terminals: In order to access different kinds of services and technologies, the user terminals should be able to configure themselves in different modes. This eliminates the need of multiple terminals. Adaptive techniques like smart antennas and software radio have been proposed for achieving terminal mobility. Wireless system discovery and selection: The main idea behind this is the user terminal should be able to select the desired wireless system. The system could be LAN, GPS, and GSM etc. One proposed solution for this is to use software radio approach. Terminal Mobility: Terminal mobility allows the user to roam across different geographical areas that uses different technologies. There are two important issues related to terminal mobility. One is location management where the system has to locate the position of the mobile for providing service. Another one is hand off management. Personal mobility: Personal mobility deals with the mobility of the user rather than the user terminals. The idea behind this is, no matter where the user is located and what device he is using, he should be able to access his messages. Security and privacy: The existing security measures for wireless systems are inadequate for 4G systems. Billing System: In 4G wireless systems, the user may use different services (like multimedia) and might switch between different service providers. Hence the operators have to design a billing architecture that provides a single bill to the user for all the services he has used. STREAMING CHALLENGES The widespread implementation of mobile streaming services faces the following major challenges: Download Speeds: The recent technology, HSDPA (3.5 G) High Speed Data Downlink Packet Access industry jargon which means the download speeds at which video or data can be sucked into a mobile phone could theoretically be as high as 10 mega bits per second (MBPS) but in practice would be around a half to onethird this speed. Streaming methodologies so far developed for
HSDPA networks provide practical speeds in Kbps only. Delivering full HD videos over a wireless spectrum will require very high data rate and low latency. Due to the fluctuation of power and bandwidth constraints and random time varying fading effect, the resource allocation has to be performed dynamically during communications to satisfy the stringent quality of service (QoS) requirements. Therefore, crosslayer design methodologies become natural choices to guarantee reliable and high-quality end-to-end performance. Scalable video coding and streaming techniques should seamlessly bridge the gaps among the huge amounts of visual data for transmission, very limited communication bandwidth, and the variety of end terminal capabilities. The next issue is the need for an efficient multicast video streaming mechanism, which enables multiple users to share the same data channel. Integrating reliable video-on-demand (VOD) broadcasting schemes in mobile data cast systems is an issue. The existing harmonic broadcasting scheme just extends the current DVB-H data cast protocol stack with a number of new modules such as scalable video coding encapsulation and point-to-point bearer. Heterogeneity: In the future, we will have access to a variety of mobile terminals with a wide range of display sizes and capabilities. In addition, different radio-access networks will make multiple maximum-access link speeds available. One way to address heterogeneity is to use appropriately designed capability exchange mechanisms that enable the terminal and media server to negotiate mobile terminal and mobile network capabilities and user preferences. This approach lets the server send multimedia data adapted to the user s mobile terminal and the network. Figure1.Mobile environment with various access networks
Another problem is how to efficiently deliver streamed multimedia content over various radio-access networks with different transmission conditions. This is achievable only if the media transport protocols incorporate the specific characteristics of wireless links, such as delays due to retransmissions of corrupted data packets. Here, proxies are a suitable approach for caching data packets and optimizing the data transport over the wireless links to a mobile terminal. ARCHITECTURAL CORE 4G wireless system is expected to be built on an IP- based core network for global routing along with more customized local area network that supports dynamic hand off mechanism and Ad-Hoc routing. Mobile IPv6 (MIPv6) is the standardized IP- based mobility protocol for IPv6. In 4G LANs will be installed everywhere like in trains, vehicles etc or might be formed in an Ad-Hoc basis by random collection of devices that happens to come in a specific radio range. New routing protocols have to be designed for such systems. In 4G mobile systems, each terminal is assigned a home agent, which has a permanent home IP address. When terminal moves to another location it obtains a new temporary address called the care-of address. The user terminal regularly updates the home agent with its current care-of address. If the user is at home, another device can communicate with the user using its home IP address. When the user moves to some other location communication is carried out using another procedure. If a host wants to communicate with the user, it first sends a setup message to the user s home agent (which the host knows). The home agent knows the care-of address of the user and it forwards the setup message to the user terminal. The home agent also forwards the care-of address of the user to the host so that future messages can be sent directly to the user. Proposed Architecture: Multimode Devices: In this configuration, a single terminal employs multiple interfaces to access different wireless system. Figure (a) shows the framework of this architecture. The requirement for this scheme is that the device should incorporate the required hardware necessary to access the different technologies. The flaw with this is that it increases the complexity of the user device which might make it
more expensive to the common user. One advantage of this architecture is that it does not require any network modification or internetworking devices. The QoS handling for this type of architecture still remains an open issue. Figure2. Multimode Devices Architecture TECHNOLOGICAL SOLUTION SETS FOR 4G: OFDMA: Orthogonal Frequency Division Multiplexing (OFDM) not only provides clear advantages for physical layer performance, but also a framework for improving layer 2 performance by proposing an additional degree of freedom. Using ODFM, it is possible to exploit the time domain, the space domain, the frequency domain and even the code domain to optimize radio channel usage. As shown in the Figure the signal is split into orthogonal subcarriers, on each of which the signal is narrowband (a few khz) and therefore immune to multi-path effects, provided a guard interval is inserted between each OFDM symbol. OFDM modulation can also be employed as a multiple access technology (Orthogonal Frequency Division Multiple Access; OFDMA). In this case, each OFDM symbol can transmit information to/from several users using a different set of subcarriers (sub channels). This not only provides additional flexibility for resource allocation (increasing the capacity), but also enables cross-layer optimization of radio link usage. Figure3. OFDM Principles Software defined radio: Software Defined Radio (SDR) benefits from today s high processing power to
develop multi-band, multi-standard base stations and terminals. In the context of 4G systems, SDR will become an enabler for the aggregation of multistandard pico/micro cells. Multiple-Input Multiple-Output: MIMO uses signal multiplexing between multiple transmitting antennas (space multiplex) and time or frequency. It is well suited to OFDM; the signal transmitted by m antennas is received by n antennas. Processing of the received signals may deliver several performance improvements: range, quality of received signal and spectrum efficiency. Interlayer optimization: The most obvious interaction is the one between MIMO and the MAC layer. Other interactions have been identified Figure 4: Layer Interaction Handover and mobility: Handover technologies based on mobile IP technology so far have been considered for data and voice. Mobile IP techniques are slow but can be accelerated with classical methods like hierarchical, fast mobile IP. These methods are applicable to data and probably also voice. In single-frequency networks, it is necessary to reconsider the handover methods. Performing vertical hand off is one of the most challenges faced by researchers working on 4G. Multimedia service delivery, service adaptation and robust transmission: Audio and video coding is scalable. For instance, a video flow can be split into three flows, which can be transported independently: one base layer (30 kbit/s), which is a robust flow but of limited quality (e.g. 5 images/s), and two enhancement flows (50 kbit/s and 200 kbit/s). The first flow provides availability, the other two; quality and definition. In a streaming situation, the terminal will have three caches. In pico cellular coverage, the parent coverage establishes the service dialog and service start-up (with the base layer). As soon as the terminal enters pico cell coverage, the terminal caches are filled, starting with the base cache. Video (and audio) transmissions are currently transmitted without error and without packet loss.
However, it is possible to allow error rates of about 10-5 /10-6 and a packet loss around 10-2 /10-3. Coded images still contain enough redundancy for error correction. It is possible to gain about 10 db in transmission with a reasonable increase in complexity. Using the described technologies, multimedia transmission can provide a good quality user experience. CONCLUSION Advances in mobile communication technologies have been rapid and their effects have frequently manifested themselves in ways and places far beyond the ones imagined by their inventors. Policy-based management and information model concepts, hierarchical Mobile IPv6, streaming standards, flexible pricing and billing schemes, capability negotiation processes, and last but not least, open technologyindependent APIs are all important building blocks of 4G mobile systems. Properly combined, the aforementioned technologies can support a 4G-system architecture that will be a far cry from its monolithic predecessors. REFERENCES 1. Wikipedia -title: 4G http://en.wikipedia.org/wiki/4g 2. 4G Network Architecture & Protocols http://www.winlab.rutgers.edu/docs/focus/m obnet2.html 3. The Streaming Media Systems Group http://www.hpl.hp.com/research/mmsl/proje cts/streaming.html 4. 4G Consortium http://www.remon-4g.org.il/ 5. Wireless World INitiative NEw Radio http://www.ist-inner.org/about.html 6.NTT Docomo - A Japanese Company working on 4G http://www.nttdocomo.com/technologies/fut ure/toward/index.html 7. Communications Network Research Institute http://www.cnri.dit.ie/research.vide o-streaming.vidas.html 8.http://4g.co.uk/