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Hw ic 3_g_4g

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  • 1. 1 3G and 4G Mobile Telephony Shao Dan, Lertrusdachakul Intuon, and Mateos Luis VIBOT Heriot Watt University, Scotland, UK Abstract—Mobile communication is one of the hottest areas that are developing extremely fast in present times, thanks to the advances of technology in all fields of mobile and wireless communications. Nowadays the use of 3G mobile communication systems seem to be the standard, while 4G stands for the next generation of wireless and mobile communications. This document studies the 3G – 4G background and the vision for the 4G. We first present a review on the development history, characteristics, status of mobile communication and related 3G - 4G perspectives. An overall 4G framework features, showing the basic keys (diversity and adaptability) of the three targets (terminals, networks, and applications). We present in both external and internal diversity of each target to illustrate the causes and solutions of the adaptability feature. Then, the 4G domain of each feature in the framework is discussed from a technical point, showing techniques and possible research issues for sufficient support of adaptability. At the end, a summary on 4G visions and some of the issues this new technology may face. Introduction Mobile communications and wireless networks are developing at an incredible speed, with evidences of significant growth in the areas of mobile subscribers and terminals, mobile and wireless access networks, and mobile services and applications. [1] The present time seem to be right to start the research of 4G mobile communications because of: •Possibility, now we are using the 3G standardization and the next generation of 4G is underway to add more capability and adaptability to the mobile communication technology. •Necessity: 3G is in use but the capabilities are not enough to the mobile communication strategy, in which many problems are only partly solved and there are still many problems left to be solved in the 4G generation. For 4G, most of the ongoing research can be classified into two different classes: 1) Many of the related 4G research focuses mainly on one specific technical area, such as distributed computing, mobile agents, multimedia services, or radio air interfaces, etc. 2) Some pieces of research are interested mainly in 4G scenarios from the standpoints of service provider or user, or a market analyst, from a less or non- technical viewpoint. We are going to present overall visions on the features of 4G mobile communications, based on a feature. Third Generation (3G) and Fourth Generation (4G) Features provides a brief review of the development history and status of mobile communications. Technical Perspective discusses the adaptability feature of each three targets in the entire 4G domain from a technical standpoint, in which promising techniques and possible research issues are proposed.
  • 2. 2 Third Generation (3G) and Fourth Generation (4G) Features In general, 3G mobile technologies are broadband capabilities with higher data rate at lower incremental cost than the 2G supporting the large number of voice and data customers especially in the urban area. It uses 5MHz channel carrier bandwidth to deliver significant higher data rate around 384 kbps for mobile systems and up to 2 Mbps for stationary systems. The greater capacity includes the spectrum efficiency improvement which allows users to access global roaming between different 3G networks. However, there are some issues against these from the 3G providers and users. For example, 3G mobile services in some countries are still high price, health effects caused by electromagnetic waves, High input fees for service licenses, lack of 2G mobile user buy-in for 3G wireless service, and lack of coverage because of the new service, etc. The International Telecommunication Union has defined the global standard for third generation wireless communication as the International Mobile Telecommunications- 2000 or IMT-2000. Within IMT-2000, it consists of UMTS, WCDMA, and CDMA2000 which can be briefly explained as follow: W-CDMA or Wideband Code Division Multiple Access. It has designed for replacing the 2G GSM network by providing the higher speed transmission protocol. It is a wideband spread-spectrum mobile air interface that utilized the direct sequence Code Division Multiple Access signaling method (CDMA) to achieve higher speed and support more users compared to Time Division Multiple Access signaling method (TDMA) used by GSM networks. W-CDMA is different in many aspects from CDMA2000. CDMA2000 transmits on several pairs of 1.25 MHz radio channel while W-CDMA transmits on a pair of 5 MHz wide radio channel. W-CDMA provides a different balance in terms of cost, capacity, performance, density. In the dense cities in Europe and Asia, W-CDMA is better suited for deployment. In 4G mobile technologies, the transmission data rate is increased up to 20Mbps. It promises the smoother streaming video and interactive multimedia, worldwide roaming, enhanced multimedia, universal access and portable devices and services at the lower cost than 3G. The global standards for fourth generation wireless communications are Orthogonal Frequency-Division Multiplexing (OFDM) and Ultra- wideband (UWB). For OFDM is a discrete multitone modulation which uses a digital multi-carrier modulation scheme and generates by using fast Fourier transform algorithm. Since it uses multi-carrier scheme, it is able to cope with severe channel conditions e.g. multipath and narrowband interference without complex equalization filters. It is also robust against narrow-band co-channel interference, intersymbol interference and fading caused by multipath propagation. It provides high spectral density, low sensitivity to time synchronization errors, and efficient implementation using FFT. However, it is sensitive to Doppler shift and sensitive to frequency synchronization problems. Moreover, there is inefficient transmitter power consumption due to linear power amplifier requirement. While Ultra-wideband (UWB) uses the radio technology which has bandwidth larger than 500 MHz or 25% of the centre frequency. The following table shows the mobile communications development starting from the first generation mobile telephony to the up coming the fourth generation mobile telephony. [2]
  • 3. 3 Table 1: Mobile Communication History and Status Technical Perspective This section is purposed to discuss mainly about possible topics research and promising techniques in replacing 3G by 4G. Fig. 1 gives an illustration of the discussion domain of 4G. Figure 1: 4G visions in domains A. Terminals To date, the “terminal” for accessing mobile services has been the mobile phone. With the advanced 3G and also the 4G in future, we can expect to see a broadening of this concept. User interfaces of terminals will vary from traditional keyboard, display, and tablet, to new interfaces based on speech, vision, touch, soft buttons, etc. These will be both general-purpose computing and communications devices, and devices with more specific purposes to serve particular marker segments. There will Property 1G 2G 2.5G 3G 4G Starting Time 1985 1992 1995 2002 2010-2012 Driven Technique Analog Signal Processing Digital Signal Processing Packet Switching Intelligent Signal Processing Intelligent Software Auto Configuration Representative Standard AMPS, TACS, NMT GSM, TDMA GPRS, I-Mode, HSCSD, EDGE IMT-2000 (UMTS, WCDMA, CDMA2000) OFDM, UWB Radio Frequency (Hz) 400M-800M 800M-900M, 1800M-1900M 2G 3G-5G Bandwidth (bps) 2.4K-30K 9.6K-14.4K 171K-384K 2M-5M 10M-20M Multi-address Technique FDMA TDMA, CDMA FDMA, TDMA, CDMA Cellular Coverage Large area Medium area Small area Mimi area Core Networks Telecom networks Telecom Networks, Some IP networks All-IP networks Service Type Voice, Mono- service, Person-to- person Voice, SMS, Mono-media, Person-to- person Data service Voice, Data, Some Multimedia, Person-to- machine Multimedia, Machine-to- machine
  • 4. 4 still be recognizable mobile phones. But many of these will have larger screens to display Internet pages or the face of the person being spoken to. There will be smaller "smart-phones" with limited web browsing and e-mail capabilities. The addition of mobile communications capabilities to laptop and palmtop computers will speed up the convergence of communications and computing, and bring to portable computing all the functions and features available on the most powerful desktop computers. There will be videophones, wrist communicators, palmtop computers, and radio modem cards for portable computers. Innovative new voice based interfaces will allow people to control their mobile communication services with voice commands. B. Networks Worldwide roll-out of 3G networks was delayed in some countries by the enormous costs of additional spectrum licensing fees. In many parts of the world 3G networks do not use the same radio frequencies as 2G, requiring mobile operators to build entirely new networks and license entirely new frequencies. So that a number of spectrum allocation decisions, spectrum standardization decisions, spectrum availability decisions, technology innovations, component development, signal processing and switching enhancements and inter-vendor cooperation have to take place before the vision of 4G will materialize. C. Applications The emerging applications for 3G and 4G wireless systems typically require highly heterogeneous and time varying quality of service from the underlying protocol layers. So adaptability will be one of the basic requirements to the development and delivery of new mobile services. Promising techniques and possible topics may include: Mobile application should refer to a user’s profile so that it can be delivered in a way most preferred by the subscriber, such as context-based personalized services. This also brings the applications with adaptability to terminals that are moving in varying locations and speeds. Techniques such as adaptive multimedia and unified messaging take the terminal characteristics into account and ensure that the service can be received and run on a terminal with the most suitable form to the host type. Conclusion After a brief review of the history of mobile communications, the 3G and 4G mobile communications feature were described. The 4G framework is based on the key concept of integration, and it has the following characteristics: 1) The core features of 4G are described as diversity and adaptability of the targets. 2) The feature of diversity includes both external and internal diversity, in which adaptability is caused by external diversity and is solved by internal diversity. Technical perspectives are presented and some techniques with its possible research issues of 4G. References [1] B.G. Evans and K. Baughan, “Visions of 4G,” Electronics & Communication Engineering Journal, Vol. 12, No. 6, pp. 293–303, Dec. 2000. [2] C. R. Casal, F. Schoute, and R. Prasald, “A novel concept for fourth generation mobile multimedia communication,” in 50th Proc. IEEE Vehicular Technology Conference, Amsterdam, Netherlands, Sep. 1999, Vol. 1, pp. 381–385.
  • 5. 5 Appendix Gannt chart.

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