Evolution of 4G-Research Directions Towards Fourth Generation Wireless Communication B.Vasavi #1 ,Mounika Marepalli #2 , Leepika Gudur #3 Associate Professor #1 , Computer Science and Engineering Hyderabad Institute of Technology and Management (HITAM) Hyderabad, A P, India Abstract- Mobile communication play a vital l role in the data and voice network front. With the deployment of mass scale 3G just around the globe, new directions are already being researched. This paper addresses the fourth generation mobile communication. The Fourth Generation (4G) Mobile Communication not only emphasizes on increase in data rate and new interfaces but it also converse the advanced wireless mobile communication. The high speed wireless access the systems in an Open Wireless Architecture (OWA) platform which has become the hub of this emerging next generation mobile technology. Based on the OWA model, 4G mobile would deliver the best business to the wireless market and Asia-Pacific which happens to be the most dynamic market of new generation mobile communication with over $100 Billion businesses in the next decade. The 4G mobile technology is the intersection and convergence of wireless mobile and wireless access around the globe. Any single architecture wireless system, including 3G, HSDPA, WiMax, etc., is a transitional solution only, and will be replaced by open wireless architecture system very soon where in various different wireless standards can be integrated and converged on open platform. The advent of 4G wireless systems has created many research opportunities. The expectations from 4G are high in terms of data rates, spectral efficiency, mobility and integration. Keywords - MIMO, GSM, WiMAX, LTE, Pre-coding. I. INTRODUCTION The first operational cellular communication system was set up in the Norway in 1981 and was followed by the similar systems in United States and United Kingdom. These first generation systems provided voice transmissions by using frequencies around 900MHz and analog modulation. The second generation (2G) of the wireless mobile network was based on low-band digital data signaling [1]. The most popular 2G wireless technology is known as Global Systems for Mobile Communications (GSM). The first GSM systems used a 25MHz frequency spectrum in the 900MHz band [11]. Initiation for 3G started in the 1980s. Initially it focused on multimedia applications such as videoconferencing for mobile phones. 3G thinking had to evolve as internet user demanded more and more wireless applications and services. As personal wireless handsets become more common than fixed telephones, it is clear that personal wireless Internet access will follow and users will want broadband Internet access. The objective of the 3G was to develop a new protocol and new technologies to further enhance the mobile experience [4]. In contrast, the new 4G framework to be established will try to accomplish new levels of user experience and multi-service capacity by also integrating all the mobile technologies that exist i.e. GSM - Global System for Mobile Communications, GPRS - General Packet Radio Service, IMT-2000-International Mobile Communications, Wi-Fi-Wireless Fidelity, Bluetooth etc. The main objectives of 4G networks can be stated in the following properties[10] : Ubiquity, Multi-service-platform and low bit-cost. To achieve the proposed goals, a very flexible network that would combine various radio access technologies must be created. This network must provide high bandwidth, from 50- 100 Mbps for high mobility users, 1Gbps for low mobility users and technologies that permit fast handoffs and efficient delivery of service. Orthogonal Frequency Division Multiplexing (OFDM) is proving to be a possible multiple access technology to be used in 4G. But OFDM comes with its own challenges like high Peak to Average Ratio, linearity concerns and phase noise. This paper proposes a solution to reduce Peak to Average Ratio by clipping method. ATLAB as used to generate the OFDM signal to prove that clipping reduces Peak to Average Ratio.The growth of the number of mobile subscribers over the last years led to a saturation of voice oriented wireless telephony. From a number of 214 million subscribers in 1997 to 1.162 millions in 2002 [1], it is predicted that by 2010 there will be 1700 million subscribers world wide [2]. It is now time to explore novel demands and to find new ways to extend the mobile concept. The first steps have already been taken by the 2.5G, which gave users access to a data network (e.g. Internet access, MMS – Multimedia Message Service). However, users and applications demanded more communication power. As an answer to this demand a new generation with new standards has been developed - 3G. In spite of the big initial euphoria that evolved this technology, only one 3G network exists in commercial use today. This network has been deployed in Japan in 2001 using international standard IMT-2000, with great success. 4G wireless is the term used to describe the fourth-generation of wireless service. 4G is a step up from 3G, which is currently the most prevalent and high-speed wireless service. 4G is only available in limited areas today. Sprint, for example uses WiMax technology for its 4G network, while Verizon Wireless uses a technology called Long Term Evolution (LTE). No matter what technology is behind it, 4G B. Vasavi et al, / (IJCSIT) International Journal of Computer Science and Information Technologies, Vol. 2 (3) , 2011, 1087-1095 1087