INTRODUCTION:Consumers demand more from their technology. Whether it is a television, cellularphone, or refrigerator, the latest technology purchase must have new features. Withthe advent of the Internet, the most-wanted feature is better, faster access toinformation. Cellular subscribers pay extra on top of their basic bills for such featuresas instant messaging, stock quotes, and even Internet access right on their phones. Butthat is far from the limit of features; manufacturers entice customers to buy newphones with photo and even video capability. It is no longer a quantum leap toenvision a time when access to all necessary information, the power of a personalcomputer, sits in the palm of one’s hand. To support such a powerful system, we needpervasive, high-speed wireless connectivity. A number of technologies currently existto provide users with high-speed digital wireless connectivity; Bluetooth and 802.11are examples. These two standards provide very high speed network connections overshort distances, typically in the tens of meters. Meanwhile, cellular providers seek toincrease speed on their long-range wireless networks. The goal is the same: long-range, high-speed wireless, which for the purposes of this report will be called 4G, forfourth-generation wireless system. Such a system does not yet exist, nor will it exist intoday’s market without standardization. Fourth-generation wireless needs to bestandardized throughout the United States due to its enticing advantages to both usersand providers.2G undoubtedly was the most widespread and the popular. 3G wasproposed with an idea of seamless technology but with its evolution the only benefitwas higher data rates. 4G on the other hand is an ultra-high-speed broadband wirelessnetwork. There are two visions for the next generation technology:-1 .Linear 4G vision2. The Concurrent 4G vision.The former vision focuses on the cellular system with very high data rates exceeding100 Mbps, whereas the latter focuses on the seamless technology provisioning acrossall the wireless systems and delivering the optimum services. The 4G technologywhich is at its infancy is suppose to allow data transfer up to 100Mbps outdoor and1Gbps indoor. This technology can provide very speedy wireless internet access tonot only stationary users but also to the mobile users. One of the terms used todescribe 4G is MAGIC—Mobile multimedia, Anytime anywhere, Global mobilitysupport, Integrated wireless solution, and Customized personal service.To achieve this approach to develop 4G the user’s functional needs and expectationsneed to be kept in view. This way the features of 4G could be specified from the user-centric approach. A top –down methodology has to be followed where it starts from:- Users’ needs and expectations, new services mapping with the functional needs,development of a relevant and pragmatic definition of 4G and developing systemdesign, services and devices. There is an insight to what users really need anddemand from their day to day life: - information with mobility, handy access tointernet with high speeds. 4G needs to user friendly, a technology that is sensitive touser personalization. This leads to minimizing the interactions between the variousapplications. There is a natural interaction among applications in a well designed
system. Terminal heterogeneity and Network heterogeneity will make 4G a success.4G needs to encompass different terminals providing them common serviceindependent of their capabilities. This seems to be a challenge for the device makersas there is a constraint to the number of access technologies supported by the user’spersonal device. This could be overcome by the development of devices withevolutionary designs and by means of personalization transfer. This means that thecustomers need to buy a single device on which they have the potential to get the rightservice without any restrictions. The technical step up of 4G in regard to 3G isseamless integration of existing and new networks, services and terminals in order tomeet ever increasing user demands. System design rules for 4G includes: -Coverage: - Widespread coverage due to exploitation of various existing networks,with the concept of vertical handover.Bandwidth: - Resource sharing among the various networks will smoothen thespectrum limitation.Power consumption: - The power consumption capability of the 4G devices needs tobe reduced so as to prolong their battery life.TECHNOLOGY USED IN 4G COMMUNICATION SYSTEM:4G is a multipurpose and versatile technology hence it can utilize almost the entirepacket switched technologies. It can use both orthogonal frequency divisionmultiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA).OFDM mechanism splits a digital signal into different narrowband and frequencies.The reason why 4G makes use of this technology lies in its ability to minimize theintervention among symbols and channels associated to data streaming.4G is alsocapable of using multiple input / multiple output technology (MIMO).this antennatechnology is used to optimize the data speed and reduce the errors in the networks.Universal Mobile Telecommunication Service (UMTS) which is basically abroadband 3G technology is also a part of 4G. This broadband technology transfersdata in the form of frames or packets. Hence it is capable of carrying voice, video,text and other types of multimedia datagram with the speed of 2Mb. UMTS is part of4G because it can enables 4G to make use of international mobile phone roaming viausing GSM (Global system for Mobile Communications).another wirelesstelecommunication technology known as time division synchronous code divisionmultiple access (TD-SCDMA) provides support to 4G to transfer both circuitswitched data like video and voice and packet switched data.4G HardwareUltra Wide Band Networks:Ultra Wideband technology, or UWB, is an advanced transmission technology thatcan be used in the implementation of a 4G network. The secret to UWB is that it istypically detected as noise. This highly specific kind of noise does not causeinterference with current radio frequency devices, but can be decoded by anotherdevice that recognizes UWB and can reassemble it back into a signal. Since the signalis disguised as noise, it can use any part of the frequency spectrum, which means thatit can use frequencies that are currently in use by other radio frequency devices.AnUltra Wideband device works by emitting a series of short, low powered electrical
pulses that are not directed at one particular frequency but rather are spread across theentire spectrum. The pulse can be called ―shaped noise‖ because it is not flat, butcurves across the spectrum. On the other hand, actual noise would look the sameacross a range of frequencies it has no shape. For this reason, regular noise that mayhave the pulse itself does not cancel out the pulse. Interference would have to spreadacross the spectrum uniformly to obscure the pulse. UWB provides greater bandwidthas much as 60 megabits per second, which is 6 times faster than today’s wirelessnetworks. It also uses significantly less power, since it transmits pulses instead of acontinuous signal. UWB uses all frequencies from high to low, thereby passingthrough objects like the sea or layers of rock. Nevertheless, because of the weaknessof the UWB signal, special smart antennas are needed to tune and aim the signal.Although UWB and smart antenna technology may play a large role in a 4G system,advanced software will be needed to process data on both the sending and receivingside. This software should be flexible, as the future wireless world will likely be aheterogeneous mix of technologies.4G Software:4G will likely become a unification of different wireless networks, including wirelessLAN technologies (e.g. IEEE 802.11), public cellular networks (2.5G, 3G), and evenpersonal area networks. Under this umbrella, 4G needs to support a wide range ofmobile devices that can roam across different types of networks (Cefriel ). Thesedevices would have to support different networks, meaning that one device wouldhave to have the capability of working on different networks. One solution to this―multi-network functional device‖ is a software defined radio.Software Defined RadioA software defined radio is one that can be configured to any radio or frequencystandard through the use of software. For example, if one was a subscriber of Sprintand moved into an area where Sprint did not have service, but Cingular did, the phonewould automatically switch from operating on a CDMA frequency to a TDMAfrequency. In addition, if a new standard were to be created, the phone would be ableto support that new standard with a simple software update. With current phones, thisis impossible. A software defined radio in the context of 4G would be able to work ondifferent broadband networks and would be able to transfer to another networkseamlessly while traveling outside of the user’s home network. A software definedradio’s best advantage is its great flexibility to be programmed for emerging wirelessstandards. It can be dynamically updated with new software without any changes inhardware and infrastructure. In order to be able to download software at any location,the data must be formatted to some standard. This is the job of the packet layer, whichwill split the data into small ―packets.‖THE STANDARDS OF 4G:ITU-R defines that 4G refers to the International Mobile TelecommunicationsAdvanced (IMT-Advanced) and must abide by requirements given below. For high mobility the peak data rate at a 4G network must be 100 Mbps and the rate of 1 Gbps for low mobility (nomadic wireless access). The technology must be dealt with all-IP packet switched network.
The capability to utilize and share resources to address concurrent users per cell. The ascendable channel bandwidth between 5 to 20 MHz and 40 MHz in a optional case. The peak link spectral efficiency of 6.75 bit/s/Hz for uplink and 15 bit/s/Hz for downlink. The system spectral efficiency should be 2.25 bit/s/Hz/cell for the indoor usage, and 3/bit/s/Hz/cell in the downlink. Across heterogeneous networks smooth handovers must be ensured. Capacity to highly serve the next generation multimedia support. The realm of telecommunications has already embraced the term 4G as a short form of advanced cellular technology that is based on MIMO transmission, OFDMA and SC-FDE technologies and all-IP architecture. The 4th Generation is developing but none could deny its promising prospects.ADVANTAGES OF 4G:In a fourth-generation wireless system, cellular providers have the opportunity to offerdata access to a wide variety of devices. The cellular network would become a datanetwork on which cellular phones could operate — as well as any other data device.Sending data over the cell phone network is a lucrative business. In the informationage, access to data is the ―killer app‖ that drives the market. The most telling exampleis growth of the Internet over the last 10 years. Wireless networks provide a uniquetwist to this product: mobility. This concept is already beginning a revolution inwireless networking, with instant access to the Internet from anywhere.The 4G technology will be able to support Interactive services like VideoConferencing (with more than 2 sites simultaneously), Wireless Internet, etc. Thebandwidth would be much wider (100 MHz) and data would be transferred at muchhigher rates. The cost of the data transfer would be comparatively very less and globalmobility would be possible. The networks will be all IP networks based on IPv6. Theantennas will be much smarter and improved access technologies like OFDM andMC-CDMA (Multi Carrier CDMA) will be used. Also the security features will bemuch better.The entire network would be packet switched (IP based). All switches would bedigital. Higher bandwidths would be available which would make cheap data transferpossible. The network security would be much tighter. Also QoS will improve. Moreefficient algorithms at the Physical layer will reduce the Inter-channel Interferenceand Co-channel Interference.CONCLUSION:There are many standards and technologies, which are still in developing process.Therefore, no one can really sure what the future 4G will look like and what servicesit will offer to people. However, we can get the general idea about 4G from academicresearch; 4G is the evolution based on 3G’s limitation and it will fulfill the idea ofWWWW (World Wide Wireless Web) offering more services and smooth globalroaming with inexpensive cost.The 4G systems not only will support the nextgeneration of mobile service, but also will support the fixed wireless networks. Thefourth generation promises to fulfill the goal of PCC (personal computing andcommunication)—a vision that affordably provides high data rates everywhere over awireless network.