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4G Wireless System Essay

ABSTRACT:

Believe it or not, 4G is coming. Before many of us even have 3G cellular service, the outlook for 4G—although still Although the new, third generation (3G) wireless technology has not yet been implemented, leading companies in the industry are already laying the groundwork for what some are calling fourth generation (4G) technology. For this purpose 4G will be as considered those technologies that are still in the planning stages and will not be deployed within the next five years. Researchers are continuing their ideas in the development of an undefined wireless world, which could become operational by 2010. It now appears that the first 4G services could arrive, not between 2010 and 2015 as originally planned, but quite a bit sooner. Parts of 4G, in fact, are taking shape right now.

Information is power, nowhere is this truer than on the battlefield, where the ability to communicate clearly and rapidly pass on information spells the difference between survival and death? 4G (4th Generation) is the technology that is going to drive a soldier in the field in future. The key to empowering the military with tactical broadband voice, video and data is 4G communications technology. This technology adopts Wireless technology on the platform of fixed networks, Advanced antennae technologies and More advanced wireless security technologies.

Next thing is about the gear for the future warrior. Our system provides a enhanced power of vision, which provides Ground Guidance, Unit Detection, Soldier Status, Target Hand-Off and provides the Soldier Rescue during the battle. The uniform along with the armor, onboard computer which will monitor soldiers’ overall physiological and psychological picture of how they are performing in the battle zone and enhanced human performance which weighs 50 pounds from head to toe against 120 pounds of the current day system present. This paper discusses about evolution, benefits and limitations of 4G communication technology.

Introduction

4G (known as Beyond 3G), an abbreviation for Fourth-Generation, term used to describe the next complete evolution in wireless communications. A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an “Anytime, Anywhere” basis, and at higher data rates than previous generations. The approaching 4G (fourth generation) mobile communication systems are projected to solve still-remaining problems of 3G (third generation) systems and to provide a wide variety of new services, from high-quality voice to high definition video to high-data-rate wireless channels.

The term 4G is used broadly to include several types of broadband wireless access communication systems, not only cellular telephone systems. One of the terms used to describe 4G is MAGIC –Mobile multimedia, anytime anywhere, Global mobility support, integrated wireless solution, and customized personal service. As a promise for the future, 4G systems, that is, cellular broadband wireless access systems have been attracting much interest in the mobile communication arena. The 4G systems not only will support the next generation of mobile service, but also will support the fixed wireless networks.

Researchers and vendors are expressing a growing interest in 4G wireless networks that support global roaming across multiple wireless and mobile networks—for example, from a cellular network to a satellite-based network to a high-bandwidth wireless LAN. With this feature, users will have access to different services, increased coverage, the convenience of a single device, one bill with reduced total access cost, and more reliable wireless access even with the failure or loss of one or more networks. 4G networks will also feature IP interoperability for seamless mobile Internet access and bit rates of 50 Mbps or more.

History

The first analog cellular systems were based on IMTS (Improved Mobile Telephone Service) and developed in 1970. The systems were “cellular” because coverage areas were split into smaller areas or cells, each of which is served by a low power transmitter and receiver.

FIRST GENERATION (1G)

1G analog system for mobile communications saw two key improvements during 1970’s: the invention of the microprocessor and the digitization of the control link between the mobile phone and the cell site. An AMPS (Advance Mobile Phone System) was first launched by US which is 1G mobile system. It is based on FDMA technology which allows users to make voice calls within one country. Access technology used-

FDMA: Frequency Division Multiple Access (FDMA) is the most common analog system. It is a technique whereby spectrum is divided up into frequencies and then assigned to users. With FDMA, only one subscriber at any given time is assigned to a channel. The channel therefore is closed to other conversations until the initial call is finished, or until it is handed-off to a different channel. A “full duplex “FDMA transmission requires two channels one for transmitting and the other for receiving. FDMA has been used for first generation analog systems.

SECOND GENERATION (2G)

2G digital cellular systems were first developed at the end of 1980’s.These systems digitized not only the control link but also the voice signal. The new system provided better quality and higher capacity at lower cost to consumers. GSM (Global System for Mobile communication) was first commercially operated digital cellular system which is based on TDMA.

Access technology used

TDMA: Time Division Multiple Access (TDMA) improves spectrum capacity by splitting each frequency into time slots. TDMA allows each user to access the entire radio frequency channel for the short period of call. Other users share this same frequency channel at different time slots. The base station continually switches from user to user on the channel.

THIRD GENERATION (3G)

3G systems provide faster communication services, including voice, fax and internet, anytime and anywhere.3G had opened the way to enabling innovative applications and services (e.g. multimedia, entertainment, information and location-based services). The first 3G network was deployed in Japan in 2001. Access technology used

CDMA: Code Division Multiple Access is based on “spread” spectrum technology. Since it is suitable for encrypted transmissions, it has long been used for military purposes. CDMA increases spectrum capacity by allowing all users to occupy all channels at the same time. Transmissions are spread over the whole radio band, and each voice or data call are assigned a unique code to differentiate from the other calls carried over the same spectrum. CDMA allows for a “soft hand-off”, which means that terminals can communicate with several base stations at the same time.

Short history of mobile technologies

What is 4G?

Fourth generation (4G) wireless was originally conceived by the Defense Advanced Research Projects Agency (DARPA), the same organization that developed the wired Internet. It is not surprising, then, that DARPA chose the same distributed architecture for the wireless Internet that had proven so successful in the wired Internet. Although experts and policymakers have yet to agree on all the aspects of 4G wireless, two characteristics have emerged as all but certain components of 4G: end-to- end Internet Protocol (IP), and peer-to-peer networking. An all IP network makes sense because consumers will want to use the same data applications they are used to in wired networks. A peer-to-peer network, where every device is both a transceiver and a router/repeater for other devices in the network, eliminates this spoke-and-hub weakness of cellular architectures, because the elimination of a single node does not disable the network.

4G technology is significant because users joining the network add mobile routers to the network infrastructure. Because users carry much of the network with them, network capacity and coverage is dynamically shifted to accommodate changing user patterns. As people congregate and create pockets of high demand, they also create additional routes for each other, thus enabling additional access to network capacity. Users will automatically hop away from congested routes to less congested routes. This permits the network to dynamically and automatically self-balance capacity, and increase network utilization. What may not be obvious is that when user devices act as routers, these devices are actually part of the network infrastructure. With a cellular infrastructure, users contribute nothing to the network.

They are just consumers competing for resources. But in wireless ad hoc peer-to- peer networks, users co-operate rather than compete for network resources. Thus, as the service gains popularity and the number of user increases, service likewise improves for all users. And there is also the 80/20 rule. With traditional wireless networks, about 80% of the cost is for site acquisition and installation, and just 20% is for the technology. Rising land and labor costs means installation costs tend to rise over time, subjecting the service providers’ business models to some challenging issues in the out years. With wireless peer-to-peer networking, however, about 80% of the cost is the technology and only 20% is the installation. Because technology costs tend to decline over time, a current viable business model should only become more profitable over time.

The devices will get cheaper, and service providers will reach economies of scale sooner because they will be able to pass on the infrastructure savings to consumers, which will further increase the rate of penetration. This new generation of wireless is intended to complement and replace the 3G systems, perhaps in 3 to 5 years. Accessing information anywhere, anytime, with a seamless connection to a wide range of information and services, and receiving a large volume of information, data, pictures, video, and so on, are the keys of the 4G infrastructures.

The future 4G infrastructures will consist of a set of various networks using IP (Internet protocol)as common protocol so that users are in control because they will be able to choose every application and environment. Based on the developing trends of mobile communication, 4G will have broader bandwidth, higher data rate, and smoother and quicker handoff and will focus on ensuring seamless service across a multitude of wireless systems and networks.

Why 4G is required?

At the first, we might have a question that why we even require 4G if 3G systems are working well. It is because of basically two reasons that one is substantial growth in overall number of subscribers and other is massive demand of new data services which can be either data, audio, image or video(interactive or non interactive). These two factors are enough to cause a substantial bottle neck in cellular communication services. Though the projected data rate is around 2Mbps in 3G, the actual data rates are slower, especially in crowded areas or when network is congested. Further the data rates also depends on the users activity (moving or steady state) and location (indoor/outdoor) as expected, the data services like multimedia are going to play modest role and will dominate the cellular traffic instead of voice in future .

In such scenario the present 1G & 2G systems will saturate and will have no room to survive. Also the demand for increasing data rates leads to higher band width requirement. These factors cause the cellular industry to develop a common standard for a system that can work to overcome almost all the limitations imposed by the previous cellular technologies. The expected features of 4G systems are much higher data rates around 100Mbps, higher bandwidth requirements of an order of hundreds of MHz, plenty of services like data, audio, video etc. It will provide Seamless connectivity and improved quality of service.

Features

1. Support for multimedia services like teleconferencing and wireless Internet.
2. Wider bandwidths and higher bitrates.
3. Global mobility and service portability.
4. Scalability of mobile network.
5. Entirely Packet-Switched networks.
6. Digital network elements.
7. Higher band widths to provide multimedia services at lower cost(up to 100 Mbps).
8. Tight network security.

4G mobile phone

4G Network

Figure shows the basic concept of 4g network. The future 4G infrastructure will consist of a set of various networks using internet protocol. As a common protocol so that the users are in control as they will be able to choose every application and environment. Accessing information anywhere, anytime with seamless connection to a wide range of information, obtaining services, receiving a large volume of information, data, pictures, video and so on are the key of 4G infrastructure.

An OFDM transmitter accepts data from an IP network, converting and encoding prior to modulation .An IFFT(inverse fast Fourier transform) transforms the OFDM signal into an IF signal, which is sent to RF transmitter. With orthogonal sub-carriers, the receiver can separate and process each sub-carrier without interference from other sub-carriers. OFDM provides better link and communication quality. It is more impervious to fading and multi-path delays than other transmission techniques.

Architecture in prospects

End-to-end Service Architectures for 4G Mobile Systems:-

A characteristic of the transition towards 3G systems and beyond is that highly integrated telecommunications service suppliers fail to provide effective economics of scale. This is primarily due to deterioration of vertical integration scalability with innovation speedup. Thus, the new rule for success in 4G telecommunications markets will be to provide one part of the puzzle and to cooperate with other suppliers to create the complete solutions that end customers require.

A direct consequence of these facts is that a radically new end-to-end service architecture will emerge during the deployment of 3G mobile networks and will became prominent as the operating model of choice for the Fourth Generation (4G) Mobile Telecommunications Networks. This novel end-to-end service architecture is inseparable from an equally radical transformation of the role of the telecommunications network operator role in the new value chain of end service provision. In fact, 4G systems will be organized not as monolithic structures deployed by a single business entity, but rather as a dynamic confederation of multiple sometimes cooperating and sometimes competing-service providers. End-to-end service architectures should have the following desirable properties:

• Open service and resource allocation model.
• Open capability negotiation and pricing model.
• Trust management. Mechanisms for managing trust relationships among clients and service providers, and between service providers, based on trusted third party monitors.
• Collaborative service constellations.
• Service fault tolerance.

Middleware Architecture:-

The service middleware is decomposed into three layers; i.e. user support layer, service support layer and network support layer. The criteria on for using a layered approach are to reuse the existing subsystems in the tradition al middleware. The user support layer has autonomous agent aspects that traditional service middleware lacks. It consists of 4 sub-systems: ‘Personalization’, ‘Adaptation’, ‘Community’ and ‘Coordination’, to provide mechanisms for context awareness and support for communities and coordination. Introduction of this functional layer enables the reduction of unnecessary user interaction with the system and the provision of user centric services realized by applying agent concepts, to support analysis of the current context, personalization depending on the user’s situation, and negotiation for service usage. The middle layer, the service support layer, contains most functionality of traditional middleware. The bottom layer, the network layer supports connectivity for all-IP networks. The dynamic service delivery pattern defines a powerful interaction model to negotiate the conditions of service delivery by using three subsystems: ‘Discovery & Advertisement’,’ Contract Notary’ and ‘Authentication & Authorization’.

Network Architecture:-

It is clear that more fundamental enhancements are necessary for the very ambitious throughput and coverage requirements of future networks. Towards that end, in addition to advanced transmission techniques and antenna technologies, some major modifications in the wireless network architecture itself, which will enable effective distribution and collection of signals to and from wireless users, are sought. The integration of “multihop” capability into the conventional wireless networks is perhaps the most promising architectural upgrade. In a Multihop network, a signal from a source may reach its destination in multiple hops (whenever necessary) through the use of “relays”.

Since we are here concerned with infra structure-based networks, either the source or destination is a common point in the network base station (or, access point, in the context of WLANs). The potential advantage of relaying is that it allows substituting a poor-quality (due to high path loss) single-hop wireless link with a composite, two or more hop, better-quality link whenever possible. Relaying is not only efficient in eliminating black spots throughout the coverage region, but more importantly ,it may extend the high data rate coverage range of a single BS ; therefore cost effective high data rate coverage may be possible through the augmentation of the relaying capability in conventional cellular networks.

Advantages:-
• Property owners can install their own access points.
– Spreads infrastructure cost.
•Reduced network access operational cost:
– Access points configure into access network.
– Some access points may be moving (bus, train)
• Multihop also could reduce costs in heterogeneous 3G networks.

e.g. of Heterogeneous network

Overlay network:-

In this architecture, a user accesses an overlay network consisting of several universal access points (UAP). These UAPs in turn select a wireless network based on availability, QoS specifications, and user defined choices. A UAP performs protocol and frequency translation, content adaptation, and QoS negotiation-renegotiation on behalf of users .The over lay network, rather than the user or device, performs handoffs as the user moves from one UAP to another. A UAP stores user, network, and device information, capabilities, and preferences .Because UAPs can keep track of the various resources a caller uses; this architecture supports single billing and subscription. (a)A multimode device lets the user, device, or network initiate handoff between networks without the need for network modification or interworking devices.

(b)An overlay network consisting of several universal access points (UAPs) that store user, network, and device information—performs a handoff as the user moves from one UAP to another.

(c)A device capable of automatically switching between networks is possible if wireless networks can support a common protocol to access a satellite-based network and another protocol for terrestrial networks.

Wireless technology used in 4G

1. OFDM
2. UWB
3. SMART ANTEENAS
4. IPv6

Orthogonal Frequency Division Multiplexing (OFDM) :-

Orthogonal FDM’s spread spectrum technique spreads the data over a lot of carriers that are spaced apart at precise frequencies. This spacing provides the “orthogonality”. In this method which prevents the receivers/demodulators from seeing frequencies other than their own specific one. The main benefit of OFDM is high spectral efficiency, but with OFDM you also get; high resiliency to RF interference, and the multi-path distortion is lower. This is handy because in a standard terrestrial broadcasting situation there are high amounts of multipath-channels. Since the various versions of the signal interfere with each other, known as inter symbol interference (ISI) it becomes incredibly hard to extract the original information. The use of the discrete Fourier transform (DFT) was originally proposed in 1971 by Weinstein and Ebert, which greatly reduces the implementation complexity of OFDM systems. This was further reduced by the development of the fast Fourier transform (FFT).

Shortly after equalization algorithm was implemented in order to help suppress both ISI and inter subcarrier interference, which is caused by the channel impulse response and timing and frequency errors. In OFDM the subcarrier pulse which is used for transmission is rectangular. This is why the capability of pulse forming and modulation can be performed by an IDFT, which can be generated very efficiently as an IFFT. Because of this, the receiver only needs a FFT to reverse this process. Taking into account the theories of the Fourier Transform the rectangular pulse shape will end up as a sin(x)/x style of spectrum of the subcarriers. In traditional FDM the sub-channels aren’t orthogonal therefore need to be separated by guard bands which obviously wastes much needed spectrum.

Because an IIFT is used for modulation in OFDM, this spacing of the subcarriers is done in such a way the frequency where we evaluate the received signal all other signals are zero thus allowing the sub-channels to overlap. But because of this, for an OFDM system to work using this method, the receiver and the transmitter must be in perfect synchronization, and there can’t be any multipath fading, which is unusual since finding a fix to this is one of the main goals of OFDM. Luckily there is an easy way to solve this problem. If a guard interval is used, which is larger than the expected delay spread, which is done by artificially extending the symbol time and then removing this extension at the receiver, the problem is solved but with only a minimal loss in bandwidth.

Ultra Wide Band (UWB)

Ultra Wideband technology, or UWB, is an advanced transmission technology that can be used in the implementation of a 4G network. The secret to UWB is that it is typically detected as noise. This highly specific kind of noise does not cause interference with current radio frequency devices, but can be decoded by another device that recognizes UWB and can reassemble it back into a signal. Since the signal is disguised as noise, it can use any part of the frequency spectrum, which means that it can use frequencies that are currently in use by other radio frequency devices. An Ultra 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 the entire spectrum. As seen in Figure, Ultra Wideband uses a frequency of between 3.1 to 10.6 GHz.

The pulse can be called “shaped noise” because it is not flat, but curves across the Spectrum. On the other hand, actual noise would look the same across a range of frequencies- it has no shape. For this reason, regular noise that may have the same frequency as the pulse itself does not cancel out the pulse. Interference would have to spread across the spectrum uniformly to obscure the pulse. UWB provides greater bandwidth — as much as 60 megabits per second, which is 6 times faster than today’s wireless networks. It also uses significantly less power, since it transmits pulses instead of a continuous signal. UWB uses all frequencies from high to low, thereby passing through objects like the sea or layers of rock. Nevertheless, because of the weakness of the UWB signal, special antennas are needed to tune and aim the signal.

UWB spectrum

Smart Anteenas

Multiple “smart antennas” can be employed to help find, tune, and turn up signal information. Since the antennas can both “listen” and “talk,” a smart antenna can send signals back in the same direction that they came from. This means that the antenna system cannot only hear many times louder, but can also respond more loudly and directly as well. There are two types of smart antennas:-

Switched Beam Anteenas – It has fixed beams of transmission, and can switch from one predefined beam to another when the user with the phone moves throughout the sector.

Adaptive Array Anteenas:- It represent the most advanced smart antenna approach to date using a variety of new signal processing algorithms to locate and track the user, minimize interference, and maximize intended signal reception.

[pic]

Smart antennas can thereby:
• Optimize available power
• Increase base station range and coverage
• Reuse available spectrum
• Increase bandwidth
• Lengthen battery life of wireless devices.

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 receiving side. This software should be flexible, as the future wireless world will likely be a heterogeneous mix of technologies. Anteena as both transmitter & receiver

IPv6

The Internet Protocol (IP) is the method or protocol which data is sent from one computer to another on the internet. Each computer (known as a host) on the Internet has at least one IP that uniquely identifies it from all other computers on the Internet. When you send or receive data (for example, an e-mail note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender’s Internet address and the receiver’s address. Any packet is sent first to a gateway computer that understands a small part of the Internet. The gateway computer reads the destination address and forwards the packet to an adjacent gateway that in turn reads the destination address and so forth across the Internet until one gateway recognizes the packet as belonging to a computer within its immediate neighborhood or domain.

That gateway then forwards the packet directly to the computer whose address is specified. Because a message is divided into a number of packets, each packet can, if necessary, be sent by a different route across the Internet. Packets can arrive in a different order than the order they were sent in. The Internet Protocol just delivers them. It’s up to another protocol, the Transmission Control Protocol (TCP) to put them back in the right order.

IP is a connectionless protocol, which means that there is no continuing connection between the end points that are communicating. Each packet that travels through the Internet is treated as an independent unit of data without any relation to any other unit of data. The reason the packets do get put in the right order is because of TCP, the connection-oriented protocol that keeps track of the packet sequence in a message. The most widely used version of IP today is Internet Protocol Version 4 (IPv4). However, IP Version 6 is also beginning to be supported.

In order to provide wireless services at anytime and anywhere, terminal mobility is a must in 4G infrastructures, terminal mobility allows mobile client to roam across boundaries of wireless networks. There are two main issues in terminal mobility: location management and hands-off management. With the location management, the system tracks and locates a mobile terminal for possible connection. Location management involves handling all the information about the roaming terminals, such as original and current located cells, authentication information, and Quality of Service (QoS) capabilities. On the other hand, handoff management maintains ongoing communications when the terminal roams. MobileIPv6 (MIPv6) is a standardized IP-based mobility protocol for Ipv6 wireless systems.

In this design, each terminal has an IPv6 home address whenever the terminal moves outside the local network, the home address becomes invalid, and the terminal obtain a new Ipv6 address (called a care-of address) in the visited network. A binding between the terminal’s home address and care-of address is updated to its home agent in order to support continuous communication. There are two types of hands-off- Horizontal handoff is performed when the terminal moves from one cell to another cell within the same wireless system. Vertical handoff, however, handles the terminal movement in two different wireless systems (e.g., from WLAN to GSM)

Quality of Services (QOS)

The Internet provides users with diverse and essential quality of service (Qos) Particularly given the increasing demand for a wide spectrum of network services.Many services, previously only provided by traditional circuit-switched networks, can now be provided on the Internet. These services, depending on their inherent characteristics, require certain degrees of QoS guarantees. Many technologies are therefore being developed to enhance the QoS capability of IP networks. Among these technologies, differentiated services (DiffServ) and MPLS are paving the way for tomorrow’s QoS services portfolio.DiffServ is based on a simple model where traffic entering a network is classified, policed, and possibly conditioned at the edges of the network, and assigned to different behaviour aggregates. Each behavior aggregate is identified by a single DS code oint (DSCP). At the core of the network, packets are fast forwarded according to the per-hop ehavior (PHB) associated with the DSCP.

By assigning traffic of different classes to different DSCPs, the DiffServ network provides different forwarding treatments and thus different levels of oS.MPLS integrates the label swapping forwarding paradigm with network layer routing. First, an explicit path, called a label switched path (LSP), is determined, and established using a signaling rotocol. A label in the packet header, rather than the IP destination address, is then used for making forwarding decisions in the network.Routers that support MPLS are called label switched routers (LSRs). The labels can be assigned to represent routes of various granularities, ranging from as coarse as the destination network down to the level of each single flow.

Moreover, numerous traffic engineering functions have been effectively achieved by MPLS. When MPLS is combined with DiffServ and constraint-based routing, they become powerful and complementary abstractions for QoS provisioning in IP backbone networks. Supporting QoS in 4G networks will be a major challenge due to varying bit rates, channel characteristics, bandwidth allocation, fault-tolerance levels, and handoff support among heterogeneous wireless networks. QoS support can occur at the packet, transaction, circuit, user, and network levels. • Transaction-level QoS describes both the time it takes to complete a transaction and the packet loss rate.

Certain transactions may be time sensitive, while others cannot tolerate any packet loss. • Circuit-level QoS includes call blocking for new as well as existing calls. It depends primarily on a network’s ability to establish and maintain the end-to-end circuit. Call routing and location management are two important circuit-level attributes. • User-level QoS depends on user mobility and application type. The new location may not support the minimum QoS needed, even with adaptive applications. In a complete wireless solution, the end-to-end communication between two users will likely involve multiple wireless networks. Because QoS will vary across different networks, the QoS for such users will likely be the minimum level these networks support.

Software defined ratio

Software Defined Radio (SDR) benefits from today’s high processing power to develop multi-band, multi-standard base stations and terminals. Although in future the terminals will adapt the air interface to the available radio access technology, at present this is done by the infrastructure. Several infrastructure gains are expected from SDR. For example, to increase network capacity at a specific time (e.g. during a sports event), an operator will reconfigure its network adding several modems at a given Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G systems, SDR will become an enabler for the aggregation of multistandard pico/micro cells. For a manufacturer, this can be a powerful aid to providing multi-standard, multi-band equipment with reduced development effort and costs through simultaneous multi-channel processing

Security

Security requirements of 2G and 3G networks have been widely studied in the literature. Different standards implement their security for their unique security requirements. For example, GSM provides highly secured voice communication among users. However, the existing security schemes for wireless systems are inadequate for 4G networks. The key concern in security designs for 4G networks is flexibility. As the existing security schemes are mainly designed for specific services, such as voice service, they may not be applicable to 4G environments that will consist of many heterogeneous systems. Moreover, the key sizes and encryption and decryption algorithms of existing schemes are also fixed. They become inflexible when applied to different technologies and devices (with varied capabilities, processing powers, and security needs). As an example, Tiny SESAME is a lightweight reconfigurable security mechanism that provides security services for multimode or IP-based applications in 4G networks.

Application

Application to Admission Control in Cellular Packet Networks:- Based on the developing trends of mobile communication, 4G will have broader bandwidth, higher data rate, and smooth er and quicker handoff and will focus on ensuring seamless service across a multitude of wireless systems and networks. The key concept is integrating the 4G capabilities with the entire existing mobile technologies through advanced technologies. Application adaptability and being highly dynamic are the main features of 4G services of interest to users. Emerging wireless technologies such as 4G tend to be packet-switched rather than circuit-switched because the packet-based architecture allows for better sharing of limited wireless resources. In a packet network, connections (packet flows) do not require dedicated circuits for the entire duration of the connection. Unfortunately, this enhanced flexibility makes it more difficult to effectively control the admission of connections into the network.

4G in normal life:-

Traffic Control

Some major cities have deployed cameras on traffic lights and send those images back to a central command center. This is generally done using fiber, which limits where the cameras can be hung, i.e., no fiber, no camera. 4G networks allow cities to deploy cameras and backhaul them wirelessly. And instead of having to backhaul every camera, cities can backhaul every third or fifth or tenth camera, using the other cameras as router/repeaters. These cameras can also serve as fixed infrastructure

Location application

4G location applications will be based on visualized, virtual navigation schemes that will support a remote database containing graphical representations of streets, buildings and another physical characteristic of a large metropolitan area. This data base could be accessed by subscribers in vehicles.

Telemedicine

A paramedic assisting a victim of a traffic accident in a remote location could access medical records (X-rays) and establish a video conference so that a remotely based surgeon could provide ‘on-scene’ assistance

Traffic Control during Disaster

If a hurricane hits the Coast and cars start driving south-east, 4G networks can allow officials to access traffic control boxes to change inland traffic lanes to green. Instead of having to send officers to every box on roads being overwhelmed by civilians who are evacuating, it can all be done remotely, and dynamically. In a September 11 type environment, lights could also be forced to red to prevent civilians from driving into harm’s way. In the event of natural disasters where the entire communications infrastructure is in disarray, restoring communications quickly is essential. With wideband wireless mobile communications, limited and even total communication capability (including Internet and video services) could be set up within hours instead of days or even weeks required at present for restoration of wire line communications

Limitations

Although the concept of 4G communications shows much promise, there are still limitations that must be addressed. A major concern is interoperability between the signaling techniques that are planned for use in 4G. Cost is another factor that could hamper the progress of 4G technology. The equipment required to implement the next-generation network are still very expensive. A Key challenge facing deployment of 4G technologies is how to make the network architectures compatible with each other. This was one of the unmet goals of 3G. As regards the operating area, rural areas and many buildings in metropolitan areas are not being served well by existing wireless networks.

Conclusion

As the history of mobile communications shows, attempts have been made to reduce a number of technologies to a single global standard. Projected 4G systems offer this promise of a standard that can be embraced worldwide through its key concept of integration. Future wireless networks will need to support diverse IP multimedia applications to allow sharing of resources among multiple users. There must be a low complexity of implementation and an efficient means of negotiation between the end users and the wireless infrastructure. The fourth generation promises to fulfill the goal of PCC (personal computing and communication)—a vision that affordably provides high data rates everywhere over a wireless network.

References-
1). Frattasi, S. Fathi, H. Fitzek, F.H.P. Prasad, R. Katz,“Defining 4G technology from the users perspective” IEEE, Jan.-Feb. 2006, Volume: 20, Issue: 1, pp 35-41 2). X. P. Costa and H. Hartenstein. “A Simulation Study on the Performance of Mobile IPv6 in a WLAN-based Cellular Network, Computer Networks”, 40(1):191–204, September 2002.

3). 4G-Advanced wireless communication, Savo g. Glisic,2nd edt, john willy & sons ltd 4). www.India times.com
5). www.3g4gblogspot.com
6). www.4G.co.uk
7). www.4gwirelessevolution.tmcnet.com


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