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Introduction

Pick up any newspaper today and it is a safe bet that you will find an article somewhere relating to mobile communications. If it is not in the technology section it will almost certainly be in the business section and relate to the increasing share prices of operators or equipment manufacturers, or acquisitions and take-overs thereof. Such is the pervasiveness of mobile communications that it is affecting virtually everyoneâ„¢s life and has become a major political topic and a significant contributor to national gross domestic product (GDP).

The major driver to change in the mobile area in the last ten years has been the massive enabling implications of digital technology, both in digital signal processing and in service provision. The equivalent driver now, and in the next five years, will be the all pervasiveness of software in both networks and terminals. The digital revolution is well underway and we stand at the doorway to the software revolution. Accompanying these changes are societal developments involving the extensions in the use of mobiles. Starting out from speech-dominated services we are now experiencing massive growth in applications involving SMS (Short Message Service) together with the start of Internet applications using WAP (Wireless Application Protocol) and i-mode. The mobile phone has not only followed the watch, the calculator and the organiser as an essential personal accessory but has subsumed all of them. With the new Internet extensions it will also lead to a convergence of the PC, hi-fl and television and provide mobility to facilities previously only available on one network.

The development from first generation analogue systems (1985) to second generation (2G) digital GSM (1992) was the heart of the digital revolution. But much more than this it was a huge success for standardisation emanating from Europe and gradually spreading globally.

However, world-wide roaming still presents some problems with pockets of US standards IS-95 (a code division multiple access [CDMA] rather than a time division multiple access [TDMA] digital system) and IS- 136 (a TDMA variant) still entrenched in some countries. Extensions to GSM (2G) via GPRS (General Packet Radio Service) and EDGE (Enhanced Data rates for GSM Evolution) (E-GPRS) as well as WAP and i-mode (so called 2.5G) will allow the transmission of higher data rates as well as speech prior to the introduction of 3G.

Mobile systems comprise a radio access together with a supporting core network. In GSM the latter is characterised by MAP (Mobile Applications Protocol), which provides the mobility management features of the system.

GSM was designed for digital speech services or for low bit rate data that could fit into a speech channel (e.g. 9.6kbit/s). It is a circuit rather than a packet oriented network and hence is inefficient for data communications. To address the rapid popularity increase of Internet services, GPRS is being added to GSM to allow packet (Internet Protocol [IP]) communications at up to about 100kbit/s.

Third generation (3G) systems were standardised in 1999. These include IMT-2000 (International Mobile Telecommunications 2000), which was standardised within ITU-R and includes the UMTS (Universal Mobile Telecommunications System) European standard from ETSI (European Telecommunications Standards Institute), the US derived CDMA 2000 and the Japanese NTT DoCoMo W-CDMA (Wideband Code Division Multiple Access) system. Such systems extend services to (multirate) high-quality multimedia and to convergent networks of fixed, cellular and satellite components. The radio air interface standards are based upon W-CDMA (UTRA FDD and UTRA TDD in UMTS, multicarrier CDMA 2000 and single carrier UWC-136 on derived US standards). The core network has not been standardised, but a group of three”evolved GSM (MAP), evolved ANSI-41 (from the American National Standards Institute) and IP-based” are all candidates. 3G is also about a diversity of terminal types, including many non-voice terminals, such as those embedded in all sorts of consumer products. Bluetooth (another standard not within the 3G orbit, but likely to be associated with it) is a short-range system that addresses such applications. Thus services from a few bits per second up to 2Mbit/s can be envisioned.

For broadband indoor wireless communications, standards such as HIPERLAN 2 (High Performance Local Area Network”ETSI™s broadband radio access network [BRAN]) and IEEE 802.lla have emerged to support IP based services and provide some QoS (quality of service) support. Such systems are based on orthogonal frequency division multiplexing (OFDM) rather than CDMA and are planned to operate in the 5GHz band.

Whereas 2G operates in 900 and 1800/1900MHz frequency bands, 3G is intended to operate in wider bandwidth allocations at 2GHz. These new frequency bands will provide wider bandwidths for some multimedia services and the first allocations have been made in some countries via spectrum auctions (e.g. in the UK, Holland and Germany) or beauty contests (in France and Italy). The opportunity has also been taken to increase competition by allowing new operators into the bands as well as extending existing operator licences. These new systems will comprise microcells as well as macrocells in order to deliver the higher capacity services efficiently. 3G and 2G will continue to coexist for some time with optimisation of service provision between them. Various modes of delivery will be used to improve coverage in urban, suburban and rural areas, with satellite (and possibly HAPS”high altitude platform stations) playing a role.

The story of the evolution of mobile radio generations is summed up in Fig. 1.

Already, as we move from 2G to 3G the convergence of communications and computing is central to the realisation of the new generation of services and applications. Digital technology enables dynamic adaptation of systems, and intercommunicating software embedded in networks and terminals allows efficient control of the new networks. This is accentuated as we move from 3G to 4G, extending the range and bit rate of services and bringing about the convergence of fixed, mobile and broadcast networks, service provision and terminal types.

This paper introduce the basic ideas and thinking behind the second phase research programme (1999-2003) of the UKâ„¢s Virtual Centre of Excellence in Mobile and Personal Communications (Mobile VCE) in the form of Ëœvisions for 4Gâ„¢. A Visions Group has been set up to produce and maintain an evolving picture of 4G and to communicate these ideas down to the work areas and researchers. The aim is to provide an umbrella vision to harmonise the research work in the various areas.

The next section explain the limitations of 3G systems and derive the drivers for 4G. The subsequent sections present Ëœthe 4G visionâ„¢ and some of the research challenges that this presents. The approach that is taken here is one of developing a technical vision. However it is based upon likely user scenarios that have been developed within the Mobile VCE


Limitations of 3G and drivers for 4G

From its basic conception to the time of roll-out took around ten years for 2G; a similar period will apply to 3G, which will commence service in 2001/2 and reach full deployment by 2005. Thus by 2010 it will be time to deploy 4G networks and, working backwards with the ten year cycle, it is clear that the year 2000 is appropriate to start with visions for 4G and a research programme aimed at the key issues. The Mobile VCEâ„¢s second phase research programme has been constructed to meet this aim.

The starting point was to look at current trends. Here we see a phenomenal growth in mobiles with an estimated global user base that will exceed one billion by 2003. Already mobile communications exceed fixed communications in several countries and it is foreseen that mobile communications will subsume fixed by 2010 (fixed”mobile convergence will be complete). Currently short messaging is booming, especially among the younger generation, with averages of upwards of 100 messages per month dominating monthly bills. Business take-up of SMS via information services is also increasing and providing a start for mobile e-commerce, but this is currently very much limited by the bit rates available. This will be improved with the introduction of GPRS.

In Europe the WAP system (using Wireless Markup Language”WML) has been slow to gain market ground; in contrast, in Japan NTT DoC0oMo™s ˜i-mode™ system had over 10 million subscribers by summer 2000 and is picking up 50000 new customers per day. Customers are already browsing the Internet, exchanging e-mail, conducting banking and stock transactions, making flight reservations and checking news and weather via HTML- based (Hyper Text Markup Language) text information on their phones. Java is expected to be available on i-mode phones soon, allowing the download of agents, games etc. and the introduction of location-based services. In Japan, the number of net phones has now passed the number of wired Internet customers and is setting the trend that others will surely follow when 3G opens up more bandwidth and improved quality.

Thus 3G will provide a significant step in the evolution of mobile personal communications. Mobility appears to be one of the fundamental elements in the evolution of the information society. As service provision based on Ëœnetwork centricâ„¢ architectures gradually gives way to the Ëœedge-centricâ„¢ architectures, access is needed from more and more places at all times. But can 3G deliver?

It is true that 3G can support multimedia Internet-type services at improved speeds and quality compared to 2G. The W-CDMA based air-interface has been designed to provide improved high-capacity coverage for medium bit rates (384 kbit/s) and limited coverage at up to 2Mbit/s (in indoor environments). Statistical multiplexing on the air also improves the efficiency of packet mode transmission. However, there are limitations with 3G as follows:

¢ Extension to higher data rates is difficult with CDMA due to excessive interference between services.
¢ It is difficult to provide a full range of multirate services, all with different QoS and performance requirements due to the constraints imposed on the core network by the air interface standard. For example, it is not a fully integrated system.

In addition, the bandwidth available in the 2GHz bands allocated for 3G will soon become saturated and there are constraints on the combination of frequency and time division duplex modes imposed by regulators to serve different environments efficiently.
By the year 2010, one of the key enabling technology developments will be embedded radio”the widespread availability and use of the $1 radio chip, which will evolve from short-range wireless developments such as Bluetooth. Embedded radio will eventually become as common as embedded microprocessors are today, with perhaps 50 such devices in the typical home, the user being mostly unaware of their presence. As they interact, in response to the user arriving home for example, they will form a home area network (HAN). Similarly, such devices will be present in large numbers in vehicles (the vehicular area network, or VAN), in personal belongings (the personal area network, or PAN), in the public environment, etc. Such chips will serve as a means of short-range communication between objects and devices, offering capabilities for monitoring and control, in most cases without the knowledge or intervention of the user.

As a person moves between these environments such short-range links will allow their personal profiles and preferences to move with them, with the hotel room automatically configuring itself to their personal preferred temperatures, TV channels/interests, lighting etc. However, the integration of such links with wide-area mobile access will enable far more powerful service concepts, as mobile agents access this pervasive network of sensors and access information on the userâ„¢s behalf to perform and even pre-empt their needs and wishes.

In the 1G to 2G transition, as well as a transition from analogue to digital we saw a mono-service to multi-service transition. From 2G to 3G, as well as a mono-media to multimedia transition we are also seeing a transition from person-to-person to person-to-machine interactions, with users accessing video, Internet/intranet and database feeds. The 3G to 4G transition, supported by such technologies, will see a transition towards a pre-dominance of automated and autonomously initiated machine-to-machine interactions.

Such developments will of course be accompanied by ongoing evolution of already anticipated 3G services, such as:
¢ send/receive e-mail
¢ Internet browsing (information)
¢ on-line transactions (e-business)
¢ location-dependent information
¢ company database access
¢ large-file transfer.

These services in themselves represent an increase in requirements for accessing information, for business and commercial transactions, as well as for a raft of new location-dependent information services, all including significantly higher bit-rate requirements. There is a requirement for a mixture of unicast, multicast and broadcast service delivery with dynamic variation between application services both spatially and temporally. Above all, there is a demand for ease of user access and manipulation, with minimal user involvement”complexity hidden from the user”and intelligence to learn and adapt with use.

From the above it will be seen that 4G will need to be highly dynamic in terms of support for:

¢ the users™ traffic
¢ air interfaces and terminal types
¢ radio environments
¢ quality-of-service types
¢ mobility patterns.

4G, then, must itself be dynamic and adaptable in all aspects, with built-in intelligence. Thus a Ëœsoftware systemâ„¢ rather than a hard-and-fixed physical system is indicated. Integration, needed to reflect the convergence issues already mentioned, is also a key to 4G, in particular integration of the radio access and the core network elements, which must be designed as a whole rather than segmented as in the past. Key drivers to 4G will be:

¢ a multitude of diverse devices (distributed, embedded, wearable, pervasive)
¢ predominance of machine-to-machine communications
¢ location-dependent and e-business applications
¢ the extension of IF protocols to mobility and range of QoS
¢ privacy and security
¢ dynamic networking and air-interfaces
¢ improved coverage mechanisms
¢ improved and dynamic spectrum usage.


4G visions mapping to research topics

The Mobile VCE vision for 2010 is embodied in the five key elements shown in Fig. 2 and detailed as follows:

¢ Fully converged services: Personal communications, information systems, broadcast and entertainment will have merged into a seamless pool of content available according to the user™s requirement. The user will have access to a wider range of services and applications, available conveniently, securely and in a manner reflecting the user™s personal preferences.
¢ Ubiquitous mobile access: The dominant mode of access to this pool of content will be mobile, accounting for all voice communications, the majority of high-speed information services, and a significant proportion of broadcast and entertainment services. Mobile access to commercial and retail services will be the norm, replacing current practices in most cases.
¢ Diverse user devices: The user will be served by a wide variety of low-cost mobile devices to access content conveniently and seamlessly. These devices will commonly be wearable”in some cases disposable” and will normally be powered independently of the mains. Devices will interact with users in a multi sensory manner, encompassing not only speech, hearing and sight but also the other human senses, and biological and environmental data pertinent to the application. Special devices tailored for people with disabilities will be common place
¢ Autonomous networks: Underlying these systems will be highly autonomous adaptive networks capable of self-management of their structure to meet the changing and evolving demands of users for both services and capacity. Efficient and cost-effective use of the radio spectrum will be an essential element of their operation, and here, too, autonomy and self- management will be the norm.
¢ Software dependency: Intelligent mobile agents will exist throughout the networks and in user devices, and will act continually to simplify tasks and ensure transparency to the user. These mobile agents will act at all levels, from managing an individual user™s content preferences to organising and reconfiguring major elements of networks.




Research challenges

Analysis of the underlying technical challenges raised by the above vision and its five elements has produced three research areas: Networks and services, Software based systems, Wireless access. These form the basis of the Mobile VCE Phase 2 research programme.

Networks and services

The aim of 3G is ˜to provide multimedia multirate mobile communications anytime and anywhere™, though this aim can only be partially met. It will be uneconomic to meet this requirement with cellular mobile radio only. 4G will extend the scenario to an all-IP network (access + core) that integrates broadcast, cellular, cordless, WLAN (wireless local area network), short-range systems and fixed wire. The vision is of integration across these network”air interfaces and of a variety of radio environments on a common, flexible and expandable platform ” a ˜network of networks™ with distinctive radio access connected to a seamless IP-based core network a (Fig. 3).



The functions contained in this vision will be:
¢ a connection layer between the radio access and the IP core including mobility management
¢ internetworking between access schemes ” inter and intra system, handover, QoS negotiations, security and mobility
¢ ability to interface with a range of new and existing radio interfaces

A vertical view of this 4G vision (Fig. 4) shows the layered structure of hierarchical cells that facilitates optimisation for different applications and in different radio environments. In this depiction we need to provide global roaming across all layers.


Both vertical and horizontal handover between different access schemes will be available to provide seamless service and quality of service.

Network reconfigurability is a means of achieving the above scenario. This encompasses terminal reconfigurability, which enables the terminal to roam across the different air interfaces by exchanging configuration software (derived from the software radio concept). It also provides dynamic service flexibility and trading of access across the different networks by dynamically optimising the network nodes in the end-to- end connection. This involves reconfiguration of protocol stacks, programmability of network nodes and reconfigurability of base stations and terminals.

The requirement is for a distributed reconfiguration control. Fig. 5 demonstrates both internal node and external network reconfigurability.


For internal reconfiguration the functionality of the network nodes must be controlled before, during and after reconfiguration and compliance to transmission standards and regulations must be facilitated.

External reconfiguration management is required to monitor traffic, to ensure that the means for transport between terminals and network gateways (or other end points) are synchronised (e.g. by conforming to standards) and to ensure that the databases/content servers needed for downloadable reconfiguration software are provided.

The research challenges are to provide mechanisms to implement internal and external configuration, to define and identify application programming interfaces (APIs) and to design mechanisms to ensure that reconfigured network nodes comply with regulatory standards.

An example of evolved system architectures is a combination of ad hoc and cellular topologies. A Ëœmobile ad hoc networkâ„¢ (MANET) is an autonomous system of mobile routers (and connected hosts) connected by wireless links. The routing and hosts are free to move randomly and organise themselves arbitrarily; thus the network wireless topology can change rapidly. Such a network can exist in a stand-alone form or be connected to a larger internet (as shown in Fig. 6).



In the current cellular systems, which are based on a star-topology, if the base stations are also considered to be mobile nodes the result becomes a Ëœnetwork of mobile nodesâ„¢ in which a base station acts as a gateway providing a bridge between two remote ad hoc networks or as a gateway to the fixed network. This architecture of hybrid star and ad hoc networks has many benefits; for example it allows self-reconfiguration and adaptability to highly variable mobile characteristics (e.g. channel conditions, traffic distribution variations, load-balancing) and it helps to minimise inaccuracies in estimating the location of mobiles.

Together with the benefits there are also some new challenges, which mainly reside in the unpredictability of the network topology due to mobility of the nodes; this unpredictability, coupled with the local-broadcast capability, provides new challenges in designing a communication system on top of an ad hoc wireless network. The following will be required:

¢ distributed MAC (medium access control) and dynamic routing support
¢ wireless service location protocols
¢ wireless dynamic host configuration protocols
¢ distributed LAC and QoS-based routing schemes.

In mobile IP networks we cannot provide absolute quality-of-service guarantees, but various levels of quality can be Ëœguaranteedâ„¢ at a cost to other resources. As the complexity of the networks and the range of the services increase there is a trade-off between resource management costs and quality of service that needs to be optimised. The whole issue of resource management in a mobile IP network is a complex trade-off of signaling, scalability, delay and offered QoS.

As already mentioned, in 4G we will encounter a whole range of new multirate services, whose traffic models in isolation and in mixed mode need to be further examined. It is likely that aggregate models will not be sufficient for the design and dynamic control of such networks. The effects of traffic scheduling, MAC and CAC (connection admission control) and mobility will be required to devise the dimensioning tools needed to design 4G networks.

Software systems

We have already seen in the previous subsection that to effect terminal and network node reconfigurability we need a middleware layer. This consists of network intelligence in the form of object-oriented distributed processing and supporting environments that offer the openness necessary to break down traditional boundaries to interoperability and uniform service provision. The mobile software agent approach is an especially important building block as it offers the ability to cope with the complexities of distributed systems. Such building blocks may reside at one time in the terminal and then in the network; or they may be composed of other objects that themselves are mobile. Within the mobile system there exists a range of objects whose naming, addressing and location are key new issues. A further step in this development is the application of the Web-service-model rather than the client/server principle; recent industry tendencies show a shift towards this paradigm and XML (extensible Markup Language) is seen as the technology of the future for Web-based distributed services. However this technology has yet to prove its scalability and suitability for future application in mobile networks.

In addition to the network utilities there will be a range of applications and services within 4G that also have associated with them objects, interfaces (APIs) and protocols. It is the entirety of different technologies that underlies the middleware for the new 4G software system.

The ˜killer application™ for 4G is likely to be the personal mobile assistant (PMA)”in effect the software complement to the personal area network”that will organise, share and enhance all of our daily routines and life situations. It will provide a range of functions including:

¢ Ability to learn from experiences and to build on personal experiences, i.e. to have intelligence
¢ Decision capability to organise routine functions with other PMAs and network data bases, e.g. diary, travel arrangements, holidays, prompts (shopping, haircut, theatre, birthdays, etc.)
¢ A range of communication modes: voice, image (with image superimposition via head-up displays such as glasses or retinal overlays), multiparty meetings (including live action video of us and our current environment), etc.
¢ Provision of navigation and positioning information and thus of location-dependent services:
¢ Detecting and reporting the location of children, pets and objects of any sort
¢ Vehicle positioning and route planning, auto pilot and pedestrian warnings
¢ Automatic reporting of accidents (to insurance companies, rescue services and car dealers)
¢ Knowledge provision via intelligent browsing of the Internet
¢ E-business facilities for purchasing and payment
¢ Health monitoring and provision of warnings
¢ Infotainment: music, video and, maybe, virtual reality

Of course the key to all this is ˜mobility™”we need to have the ˜PMA™ whenever and wherever we are, and this places additional complexity on network and service objects and the agents that process them.

Specifically we need to consider what the metrics are that determine which objects follow the user. Some objects can move anywhere; others can move in some directions or within a constrained area. If they can move, how will the existing service determine if resources are available to support them in their new (temporary) home? Will they still be able to function? What kind of computing architecture and middleware platforms will be capable of supporting thousands, perhaps millions, of such objects?

Aspects of security pervade the whole of this area. Rules of authentication, confidentiality, scalability and availability must now be applied to objects that are continuously mobile. A whole set of conditions that are valid at one time and place maybe invalid if transferred to another. Integrity and correctness issues must be considered when mechanisms that support applications are used in practice in the presence of other; distributed algorithms. For issues such as liveness, safety and boundedness”consistency, isolation and durability” execution semantics need to be evidenced for extension to the mobile environment.

Distributed management tools, in a complementary way, will allow a certain level of monitoring (including collection of data for analysis), control and troubleshooting. The management tools currently available do not encompass mobility efficiently and hence this is another important area of research.

The aim of the research in this area is to develop tools that can be used in 4G software systems. The following specific scenarios are being addressed in order to focus the issues:
¢ E-commerce, including microtransactions, share trading and internal business transactions
¢ Home services, ranging from terminal enhancements (e.g. enhancing the display capabilities by using the TV screen as a display unit for the terminal) to security systems and housekeeping tasks
¢ Transportation systems: Itinerary support, ticketing and location services are to be targeted in this area.
¢ Infotainment on the move: This will demonstrate the need for software and terminal reconfiguration and media-adaptation.
¢ Telemedicine and assistance services: Emergency team support, remote/virtual operations and surveillance of heart patients are possible stages for this scenario.

This list of scenarios can be expanded arbitrarily and also into non-consumer areas (i.e. military and emergency services), however the preconditions for service delivery and demands on the network infrastructure remain the same: they will have to be adaptable to meet the user- requirements current in 2010. Support for these scenarios may be given by intelligent agents, which may represent the terminal within the network to manage the adaptations or customisations of the communication path. On an application or service layer they may additionally be used to complete business transactions for the user (e.g. booking a theatre ticket or a flight) or to support other services. Furthermore, distributed software entities (including the variety of models from objects, via agents, to the Web-service model) will encompass management and support for applications and services as well as for user and terminal mobility.

Wireless access

In the previous two sections we have looked at the type of network and the software platforms needed to reconfigure, adapt, manage and control a diversity of multimedia, multirate services and network connections. We have seen that there will be a range of radio access air interfaces optimised to the environments and the service sets that they support. The reconfigurability and the middleware flow through to the wireless access network. The radio part of the 4G system will be driven by the different radio environments, the spectrum constraints and the requirement to operate at varying and much higher bit rates and in a packet mode. Thus the drivers are:

¢ Adaptive reconfigurability”algorithms
¢ Spectral efficiency”air interface design and allocation of bandwidth
¢ Environment coverage”all pervasive
¢ Software”for the radio and the network access
¢ Technology”embedded/wearable/low-power/high communication time/displays.

It has been decided within Mobile VCE not to become involved in technology issues or in the design of terminals. This is a large area, which is much closer to products and better suited to industry. The remaining drivers are all considered within the research programme.

It is possible, in principle, to increase significantly the effective bit rate capacity of a given bandwidth by using adaptive signal processing at both the base station and the mobile. In 3G systems adaptive signal processing has been restricted to the base station and so the challenge is to migrate this to the terminal and, most importantly, to make the two ends co-operative. Such techniques require close co-operation between the base and mobile stations in signalling information on channel quality, whilst making decisions and allocating resources dynamically. In addition, the capabilities of both ends of the link must be known reciprocally as the channel varies in both time and space. In order to optimise a link continuously, the wireless network must acquire and process accurate knowledge of metrics that indicate the current system performance, e.g. noise, inter- and intra-system interference, location, movement variations, and channel quality prediction. Such information and its accuracy must be passed to the higher layers of the system protocol that make decisions and effect resource allocation. The emphasis on the base station in 3G systems is obvious as this has the resources, real estate and capacity to implement the spatial”temporal digital signal processing needed for antenna arrays together with advanced receiver architectures. The challenge will be to migrate this to the much smaller terminal via efficient electronics and algorithms that will still allow a range of services and good call time. The availability of individual link metrics can also be used at a network level to optimise dynamically the network radio resources and to produce a self-planning network.

Arguably the most significant driver in the wireless access is the bandwidth availability and usage and whereabouts in the spectrum it will fall. Currently 3G technology is based around bands at 2GHz, but limited spectrum is available, even with the addition of the expansion bands. The higher bit rates envisaged for 4G networks will require more bandwidth. Where is this to be found? The scope for a world-wide bandwidth allocation is severely constrained and, even if this were feasible, the bandwidth would be very limited. The requirements are thus for much more efficient utilisation of the spectrum and, perhaps, new ideas for system co-existence. If the bandwidth is fixed we need to seek a spectrally more efficient air interface and this involves a consideration of various multiple access, modulation, coding, equalisation/interference cancellation, power control, etc. schemes. In view of our previous comments it is clear that all components of this air interface must be dynamically adaptive. As the whole network is to be IP based this will mean extremely rapid adaptation on a burst basis. In 4G systems we need to accomplish this at much higher and variable bit rates as well as in different environments (indoor, outdoor, broadcast, etc.) and in the presence of other adaptive parameters in the air interface. In time-domain systems equalisers would need to be adaptive and this raises questions of complexity. For CDMA, systems could use multicodes and adaptive interference cancellation, which again raise complexity issues. Alternatively one could move to OFDM-like systems (as in WLANs), which offer some reduction in complexity by operating in the frequency domain but raise other issues, such as synchronisation. The choice of the air interfaceâ„¢s multiple access scheme and adaptive components will need to be based upon the ease of adaptation and reconfigurability and on the complexity. There are also significant research challenges in this area of flexible advanced terminal architectures that are not rooted solely in physical layer problems.

A further aspect of spectrum efficiency relates to the way in which regulators allocate bandwidth. The current practice of exclusive licensing of a block of spectrum is arguably not the most efficient. It would be much more efficient to allow different operators and radio standards to co-exist in the same spectrum by dynamically allocating spectrum as loading demands. Indeed, the higher bit-rate services may need to spread their requirements across several segments of spectrum. There would then be a need for a set of rules to govern the dynamic allocation of the spectrum”a self organising set of systems to maximise the use of spectrum and balance the load. Given the degree of co-operation and the processing already envisioned this should be a realistic aim.
A great deal of work on the characterisation of radio environments has already been performed in the 2GHz and 5GHz bands within the first phase of Mobile VCE™s research, and spatial”temporal channel models have been produced. However, 4G systems will incorporate smart antennas at both ends of the radio link with the aim of using antenna diversity in the tasks of canceling out interference and assisting in signal extraction. This implies that direction-of-arrival information, including all multipath components, will be an important parameter in determining the performance of array processing techniques. There is a need to augment models with such data for both the base station and the terminal station. A more open question is where to position the next frequency bands for mobile communications. An early study is needed here in advance of more detailed radio environment characterisations.

Coverage is likely to remain a problem throughout the lifetime of 3G systems. The network-of-networks structure of 4G systems, together with the addition of multimedia, multirate services, mean that coverage will continue to present challenges. We have already seen that the likely structure will be based upon a hierarchical arrangement of macro-, micro- and picocells. Superimposed on this will be the megacell, which will provide the integration of broadcast services in a wider sense. Until now, it has been assumed that satellites would provide such an overlay, and indeed they will in some areas of the world. However, another attractive alternative could be high-altitude platform stations (HAPS), which have many benefits, particularly in aiding integration.

HAPS are not an alternative to satellite communications, rather they are a complementary element to terrestrial network architectures, mainly providing overlaid macro-/microcells for underlaid picocells supported through ground-based terrestrial mobile systems. These platforms can be made quasi- stationary at an altitude around 21”25 km in the stratospheric layer and project hundreds of cells over metropolitan areas (Fig. 7).

Due to the large coverage provided by each platform, they are highly suitable for providing local broadcasting services. A communication payload supporting 3G/4G and terrestrial DAB/DVD air interfaces and spectrum could also support broadband and very asymmetric services more efficiently than 3G/4G or DAB/DVD air- interfaces could individually. ITU-R has already recognised the use of HAPS as high base stations as an option for part of the terrestrial delivery of IMT-2000 in the bands 1885”1980 MHz, 2010”2025 MHz and 2110”2170 MHz in Regions 1 and 3, and 1885”1980 MHz and 2110”2160 MHz in Region 2 (Recommendation ITU-R M (IMT-HAPS)).

HAPS have many other advantages in reducing terrestrial real-estate problems, achieving rapid roll-out, providing improved interface management to hundreds of cells, spectrally efficient delivery of multicast/broadcast, provision of location-based services and, of course, integration. The research challenge is to integrate terrestrial and HAPS radio access so as to enhance spectral efficiency and preserve QoS for the range of services offered.

Software, algorithms and technology are the keys to the wireless access sector. Interplay between them will be the key to the eventual system selection, but the Mobile VCEâ„¢s research programme will not be constrained in this way. The aim is to research new techniques which themselves will form the building blocks of 4G.



Conclusion

It is always dangerous to predict too far ahead in a fast- moving field such as mobile communications. Almost by definition the eventual 2010 scene will not match exactly that depicted in the 4G vision described herein. However, the key elements”fully converged services, ubiquitous mobile access, diverse user devices, autonomous networks and software dependency”will persist. The 4G Vision is a living document which intends to update and amend as time and knowledge progress. It will act as the umbrella vision to a large research programme and place in context the detailed research work that will take place in the various areas. In this respect it will help to continuously steer the research as it progresses and, therefore, to make it more relevant and beneficial.



References

1 TUTFLEBEE, W. H. W.: ˜Mobile VCE: the convergence of industry and academia™, Electron. Commun. Eng. J., December 2000, 12, (6), pp.245”248
2 IRVINE, J., et al.: ËœMobile VCE scenariosâ„¢. A document produced as part of the Software Based Systems work area within the Mobile VCE Core 2 research programme, September 2000. See http://www.mobilevce.com
3 ËœWireless Strategic Initiativeâ„¢. An EU project. See http://www.ist-wsi.org
4 Foresight ITEC Group: ËœVisionsâ„¢. See http://www.foresight. gov.uk



ABSTRACT

As the virtual centre of excellence in mobile and personal communications (Mobile VCE) moves into its second core research programme it has been decided to set up a fourth generation (4G) visions group aimed at harmonising the research work across the work areas and amongst the numerous researchers working on the programme. This paper outlines the initial work of the group and provides a start to what will become an evolving vision of 4G. A short history of previous generations of mobile communications systems and a discussion of the limitations of third generation (3G) systems are followed by a vision of 4G for 2010 based on five elements: fully converged services, ubiquitous mobile access, diverse user devices, autonomous networks and software dependency. This vision is developed in more detail from a technology viewpoint into the key areas of networks and services, software systems and wireless access.


CONTENTS

¢ INTRODUCTION
¢ LIMITATIONS OF 3G AND DRIVERS FOR 4G
¢ 4G VISIONS MAPPING TO RESEARCH TOPICS
¢ RESEARCH CHALLENGES
¢ CONCLUSION
¢ REFERENCES

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4G WIRELESS SYSTEMS SEMINAR REPORT

ABSTRACT
Fourth generation wireless system is a packet switched wireless system with wide area coverage and high throughput. It is designed to be cost effective and to provide high spectral efficiency . The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB),and Millimeter wireless. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.The high performance is achieved by the use of long term channel prediction, in both time and frequency, scheduling among users and smart antennas combined with adaptive modulation and power control. Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.


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ANAND V


1. INTRODUCTION
Wireless mobile-communications systems are uniquely identified by "generation" designations. Introduced in the early 1980s, first-generation (1G) systems were marked by analog-frequency modulation and used primarily for voice communications. Second - generation (2G) wireless-communications systems, which made their appearance in the late 1980s, were also used mainly for voice transmission and reception The wireless system in widespread use today goes by the name of 2.5G”an "in-between" service that serves as a stepping stone to 3G. Whereby 2G communications is generally associated with Global System for Mobile (GSM) service, 2.5G is usually identified as being "fueled" by General Packet Radio Services (GPRS) along with GSM.
In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive-media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidth”these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension" of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up
to 200km/hr.Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.
2. FEATURES:
¢ Support for interactive multimedia, voice, streaming video, Internet, and other broadband services
¢ IP based mobile system
¢ High speed, high capacity, and low cost-per-bit
¢ Global access, service portability, and scalable mobile services
¢ Seamless switching, and a variety of Quality of Service-driven services
¢ Better scheduling and call-admission-control techniques
¢ Ad-hoc and multi-hop networks (the strict delay requirements of voice make multi-hop network service a difficult problem)
¢ Better spectral efficiency
¢ Seamless network of multiple protocols and air interfaces (since 4G will be all-IP, look for 4G systems to be compatible with all common network technologies, including 802.11, WCDMA, Bluetooth, and Hyper LAN).
¢ An infrastructure to handle pre-existing 3G systems along with other wireless technologies, some of which are currently under development.
3. HISTORY:
The history and evolution of mobile service from the 1G(first generation) to fourth generation are as follows. The process began with the designs in the 1970s that have become known as 1G. The earliest systems were implemented based on analog technology and the basic cellular structure of mobile communication. Many fundamental problems were solved by these early systems. Numerous incompatible analog systems were placed in service around the world during the 1980s.The 2G (second generation) systems designed in the 1980s were still used mainly for voice applications but were based on digital technology, including digital signal processing techniques. These 2G systems provided circuit-switched data communication services at a low speed. The competitive rush to design and implement digital systems led again to a variety of different and incompatible standards such as GSM (global system mobile), TDMA (time division multiple access); PDC (personal digital cellular) and CDMA (code division multiple access).These systems operate nationwide or internationally and are today's mainstream systems, although the data rate for users in these system is very limited. During the 1990â„¢s the next, or 3G, mobile system, which would eliminate previous incompatibilities and become a truly global system. The 3G system would have higher quality voice channels, as well as broadband data capabilities, up to 2 Mbps.An interim step is being taken between 2G and 3G, the 2.5G. It is basically an enhancement of the two major 2G technologies to provide increased capacity on the 2G RF (radio frequency) channels and to introduce higher throughput for data service, up to 384 kbps. A very important aspect of 2.5G is that the data channels are optimized for packet data, which introduces access to the Internet from mobile devices, whether telephone, PDA (personal digital assistant), or laptop. However, the demand for higher access speed multimedia communication in today's society, which greatly depends on computer communication in digital format, seems unlimited. According to the historical indication of a generation revolution occurring once a decade, the present appears to be the right time to begin the research on a 4G mobile communication system.
4.ABOUT 4G:
This new generation of wireless is intended to complement and replace the 3G systems, perhaps in 5 to 10 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 a 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. The key concept is integrating the 4G capabilities with all of the existing mobile technologies through advanced technologies. Application adaptability and being highly dynamic are the main features of 4G services of interest to users. These features mean services can be delivered and be available to the personal preference of different users and support the users' traffic, air interfaces, radio environment, and quality of service. Connection with the network applications can be transferred into various forms and levels correctly and efficiently. The dominant methods of access to this pool of information will be the mobile telephone, PDA, and laptop to seamlessly access the voice communication, high-speed information services, and entertainment broadcast services. The fourth generation will encompass all systems from various networks, public to private; operator-driven broadband networks to personal areas; and ad hoc networks. The 4G systems will interoperate with 2G and 3G systems, as well as with digital (broadband) broadcasting systems. In addition, 4G systems will be fully IP-based wireless Internet. This all-encompassing integrated perspective shows the broad range of systems that the fourth generation intends to integrate, from satellite broadband to high altitude platform to cellular 3G and 3G systems to WLL (wireless local loop) and FWA (fixed wireless access) to WLAN (wireless local area network) and PAN (personal area network),all with IP as the integrating mechanism. With 4G, a range of new services and models will be available. These services and models need to be further examined for their interface with the design of 4G systems.

5.IMPLEMENTATION USING 4G
The goal of 4G is to replace the current proliferation of core mobile networks with a single worldwide core network standard, based on IP for control, video, packet data, and voice. This will provide uniform video, voice, and data services to the mobile host, based entirely on IP.

Fig:1
The objective is to offer seamless multimedia services to users accessing an all IP-based infrastructure through heterogeneous access technologies. IP is assumed to act as an adhesive for providing global connectivity and mobility among networks.
An all IP-based 4G wireless network has inherent advantages over its predecessors. It is compatible with, and independent of the underlying radio access technology. An IP wireless network replaces the old Signaling System 7 (SS7) telecommunications protocol, which is considered massively redundant. This is because SS7 signal transmission consumes a larger part of network bandwidth even when there is no signaling traffic for the simple reason that it uses a call setup mechanism to reserve bandwidth, rather time/frequency slots in the radio waves. IP networks, on the other hand, are connectionless and use the slots only when they have data to send. Hence there is optimum usage of the available bandwidth. Today, wireless communications are heavily biased toward voice, even though studies indicate that growth in wireless data traffic is rising exponentially relative to demand for voice traffic. Because an all IP core layer is easily scalable, it is ideally suited to meet this challenge. The goal is a merged data/voice/multimedia network.
6.TRANSMISSION

Fig:2
An OFDM transmitter accepts data from an IP network, converting and encoding the data prior to modulation. An IFFT (inverse fast Fourier transform) transforms the OFDM signal into an IF analog signal, which is sent to the RF transceiver. The receiver circuit reconstructs the data by reversing this process. With orthogonal sub-carriers, the receiver can separate and process each sub-carrier without interference from other sub-carriers. More impervious to fading and multi-path delays than other wireless transmission techniques, ODFM provides better link and communication quality.
7.Wireless Technologies Used In 4G
1. OFDM
2. UWB
3. MILLIMETER WIRELESS
4. SMART ANTENNAS
5. LONG TERM POWER PREDICTION
6. SHEDULING AMONG USERS
7. ADAPTIVE MODULATION AND POWER CONTROL
7.1 Orthogonal Frequency Division Multiplexing:
OFDM, a form of multi-carrier modulation, works by dividing the data stream for transmission at a bandwidth B into N multiple and parallel bit streams, spaced B/N apart (Figure 3). Each of the parallel bit streams has a much lower bit rate than the original bit stream, but their summation can provide very high data rates. N orthogonal sub-carriers modulate the parallel bit streams, which are then summed prior to transmission.


Fig:3
An OFDM transmitter accepts data from an IP network, converting and encoding the data prior to modulation. An IFFT (inverse fast Fourier transform) transforms the OFDM signal into an IF analog signal, which is sent to the RF transceiver. The receiver circuit reconstructs the data by reversing this process. With orthogonal sub-carriers, the receiver can separate and process each sub-carrier without interference from other sub-carriers. More impervious to fading and multi-path delays than other wireless transmission techniques, ODFM provides better link and communication quality.
7.1.1Error Correcting:
4G's error-correction will most likely use some type of concatenated coding and will provide multiple Quality of Service (QoS) levels. Forward error-correction (FEC) coding adds redundancy to a transmitted message through encoding prior to transmission. The advantages of concatenated coding (Viterbi/Reed-Solomon) over convolutional coding (Viterbi) are enhanced system performance through the combining of two or more constituent codes (such as a Reed-Solomon and a convolutional code) into one concatenated code. The combination can improve error correction or combine error correction with error detection (useful, for example, for implementing an Automatic Repeat Request if an error is found). FEC using concatenated coding allows a communications system to send larger block sizes while reducing bit-error rates.
7.2 Ultra Wide Band :
A UWB transmitter spreads its signal over a wide portion of the RF spectrum, generally 1 GHz wide or more, above 3.1GHz. The FCC has chosen UWB frequencies to minimize interference to other commonly used equipment, such as televisions and radios. This frequency range also puts UWB equipment above the 2.4 GHz range of microwave ovens and modern cordless phones, but below 802.11a wireless Ethernet, which operates at 5 GHz.
UWB equipment transmits very narrow RF pulses”low power and short pulse period means the signal, although of wide bandwidth, falls below the threshold detection of most RF receivers. Traditional RF equipment uses an RF carrier to transmit a modulated signal in the frequency domain, moving the signal from a base band to the carrier frequency the transmitter uses. UWB is "carrier-free", since the technology works by modulating a pulse, on the order of tens of microwatts, resulting in a waveform occupying a very wide frequency domain. The wide bandwidth of a UWB signal is a two-edged sword. The signal is relatively secure against interference and has the potential for very high-rate wireless broadband access and speed. On the other hand, the signal also has the potential to interfere with other wireless transmissions. In addition, the low-power constraints placed on UWB by the FCC, due to its potential interference with other RF signals, significantly limits the range of UWB equipment (but still makes it a viable LAN technology).
One distinct advantage of UWB is its immunity to multi-path distortion and interference. Multi-path propagation occurs when a transmitted signal takes different paths when propagating from source to destination. The various paths are caused by the signal bouncing off objects between the transmitter and receiver”for example, furniture and walls in a house, or trees and buildings in an outdoor environment. One part of the signal may go directly to the receiver while another; deflected part will encounter delay and take longer to reach the receiver. Multi-path delay causes the information symbols in the signal to overlap, confusing the receiver”this is known as inter-symbol interference (ISI). Because the signal's shape conveys transmitted information, the receiver will make mistakes when demodulating the information in the signal. For long-enough delays, bit errors in the packet will occur since the receiver can't distinguish the symbols and correctly interpret the corresponding bits.
The short time-span of UWB waveforms”typically hundreds of picoseconds to a few nanoseconds”means that delays caused by the transmitted signal bouncing off objects are much longer than the width of the original UWB pulse, virtually eliminating ISI from overlapping signals. This makes UWB technology particularly useful for intra-structure and mobile communications applications, minimizing S/N reduction and bit errors.
7.3 Millimeter Wireless:
Using the millimeter-wave band (above 20 GHz) for wireless service is particularly interesting, due to the availability in this region of bandwidth resources committed by the governments of some countries to unlicensed cellular and other wireless applications. If deployed in a 4G system, millimeter wireless would constitute only one of several frequency bands, with the 5 GHz band most likely dominant.
7.4 Smart Antennas:
A smart antenna system comprises multiple antenna elements with signal processing to automatically optimize the antennas' radiation (transmitter) and/or reception (receiver) patterns in response to the signal environment. One smart-antenna variation in particular, MIMO, shows promise in 4G systems, particularly since the antenna systems at both transmitter and receiver are usually a limiting factor when attempting to support increased data rates.
MIMO (Multi-Input Multi-Output) is a smart antenna system where 'smartness' is considered at both transmitter and the receiver. MIMO represents space-division multiplexing (SDM)”information signals are multiplexed on spatially separated N multiple antennas and received on M antennas. Figure 4 shows a general block diagram of a MIMO system. Some systems may not employ the signal-processing block on the transmitter side.

Fig:4
Multiple antennas at both the transmitter and the receiver provide essentially multiple parallel channels that operate simultaneously on the same frequency band and at the same time. This results in high spectral efficiencies in a rich scattering environment (high multi-path), since you can transmit multiple data streams or signals over the channel simultaneously. Field experiments by several organizations have shown that a MIMO system, combined with adaptive coding and modulation, interference cancellation, and beam-forming technologies, can boost useful channel capacity by at least an order of magnitude.
7.5 Long Term Power Prediction:
Channels to different mobile users will fade independently. If the channel properties of all users in a cell can be predicted a number of milliseconds ahead, then it would be possible to distribute the transmission load among the users in an optimal way while fulfilling certain specified constraints on throughput and delays. The channel time-frequency pattern will depend on the scattering environment and on the velocity of the moving terminal.
In order to take the advantage the channel variability, we use OFDM system with spacing between subcarrires such that no interchannel interface occurs for the worst case channel scenario
(Low coherence bandwidth).A time-frequency grid constituting of regions of one time slot and several subcarriers is used such that the channel is fairly constant over each region. These time-frequency regions are then allocated to the different users by a scheduling algorithm according to some criterion.
7.6 Scheduling among Users:
To optimize the system throughput, under specified QoS requirements and delay constraints, scheduling will be used on different levels:
7.6.1 Among sectors:-In order to cope with co-channel interference among neighboring sectors in adjacent cells, time slots are allocated according to the traffic load in each sector .Information on the traffic load is exchanged infrequently via an inquiry procedure. In this way the interference can be minimized and higher capacity be obtained.
After an inquiry to adjacent cells, the involved base stations determine the allocation of slots to be used by each base station in each sector. The inquiry process can also include synchronization information to align the transmission of packets at different base stations to further enhance performance.
7.6.2 Among users:-Based on the time slot allocation obtained from inquiry process, the user scheduler will distribute time-frequency regions among the users of each sector based on their current channel predictions. Here different degrees of sophistication can be used to achieve different transmission goals.
7.7 Adaptive modulation and power control:
In a fading environment and for a highly loaded system there will almost exist users with good channel conditions. Regardless of the choice of criterion, which could be either maximization of system throughput or
equalization to user satisfaction, the modulation format for the scheduled user is selected according to the predicted signal to noise and interference ratio.
By using sufficiently small time-frequency bins the channel can be made approximately constant within bins. We can thus use a flat fading AWGN channel assumption. Furthermore since we have already determined the time slot allocation, via the inquiry process among adjacent cells described above we may use an aggressive power control scheme, while keeping the interference on an acceptable level.
For every timeslot, the time-frequency bins in the grid represent separate channels. For such channels the optimum rate and power allocation for maximizing the throughput can be calculated under a total average power constraint. The optimum strategy is to let one user, the one with best channel, transmit in each of the parallel channels.
8.ISSUES:
The first issue deals with optimal choice of access technology, or how to be best connected. Given that a user may be offered connectivity from more than one technology at any one time, one has to consider how the terminal and an overlay network choose the radio access technology suitable for services the user is accessing.
There are several network technologies available today, which can be viewed as complementary. For example, WLAN is best suited for high data
rate indoor coverage. GPRS or UMTS, on the other hand, are best suited for nation wide coverage and can be regarded as wide area networks, providing a higher degree of mobility. Thus a user of the mobile terminal or the network needs to make the optimal choice of radio access technology among all those available. A handover algorithm should both determine which network to connect to as well as when to perform a handover between the different networks. Ideally, the handover algorithm would assure that the best overall wireless link is chosen. The network selection strategy should take into consideration the type of application being run by the user at the time of handover. This ensures stability as well as optimal bandwidth for interactive and background services.
The second issue regards the design of a mobility enabled IP networking architecture, which contains the functionality to deal with mobility between access technologies. This includes fast, seamless vertical (between heterogeneous technologies) handovers (IP micro-mobility), quality of service (QoS), security and accounting. Real-time applications in the future will require fast/seamless handovers for smooth operation.
Mobility in IPv6 is not optimized to take advantage of specific mechanisms that may be deployed in different administrative domains. Instead, IPv6 provides mobility in a manner that resembles only simple portability. To enhance Mobility in IPv6, Ëœmicro-mobilityâ„¢ protocols (such as Hawaii[5], Cellular IP[6] and Hierarchical Mobile IPv6[7]) have been developed
for seamless handovers i.e. handovers that result in minimal handover delay, minimal packet loss, and minimal loss of communication state.
The third issue concerns the adaptation of multimedia transmission across 4G networks. Indeed multimedia will be a main service feature of 4G networks, and changing radio access networks may in particular result in drastic changes in the network condition. Thus the framework for multimedia transmission must be adaptive. In cellular networks such as UMTS, users compete for scarce and expensive bandwidth.
Variable bit rate services provide a way to ensure service provisioning at lower costs. In addition the radio environment has dynamics that renders it difficult to provide a guaranteed network service. This requires that the services are adaptive and robust against varying radio conditions.
High variations in the network Quality of Service (QoS) leads to significant variations of the multimedia quality. The result could sometimes be unacceptable to the users. Avoiding this requires choosing an adaptive encoding framework for multimedia transmission. The network should signal QoS variations to allow the application to be aware in real time of the network conditions. User interactions will help to ensure personalized adaptation of the multimedia presentation.
9.MOBILITY MANAGEMENT
Features of mobility management in Ipv6:
128-bit address space provides a sufficiently large number of addresses
High quality support for real-time audio and video transmission, short/bursty connections of web applications, peer-to-peer applications, etc.
Faster packet delivery, decreased cost of processing “ no header checksum at each relay, fragmentation only at endpoints.
Smooth handoff when the mobile host travels from one subnet to another, causing a change in its Care-of Address.
10.APPLICATIONS
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. So instead of carriers subsidizing the cost of user devices (e.g., handsets, PDAs, of laptop computers), consumers actually subsidize and help deploy the network for the carrier. 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 cooperate “ rather than compete “ for network resources. Thus, as the service gains popularity and the number of users 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.
10.1 4G Car
With the hype of 3G wireless in the rear view mirror, but the reality of truly mobile broadband data seemingly too far in the future to be visible yet on the information super highway, it may seem premature to offer a test drive 4G. But the good news is, 4G is finally coming to a showroom near you.
10.2 4G and public safety

There are sweeping changes taking place in transportation and intelligent highways, generally referred to as Intelligent Transportation Systems (ITS). ITS is comprised of a number of technologies, including information processing, communications, control, and electronics. Using these technologies with our transportation systems, and allowing first responders access to them, will help prevent - or certainly mitigate - future disasters. Communications, and the cooperation and collaboration it affords, is a key element of any effective disaster response. Historically, this has been done with bulky handheld radios that provide only voice to a team in a common sector. And this architecture is still cellular, with a singular point of failure, because all transmissions to a given cell must pass through that one cell. If the cell tower is destroyed in the disaster, traditional wireless service is eliminated.
4G wireless eliminates this spoke-and-hub weakness of cellular architectures because the destruction of a single node does not disable the network. Instead of a user being dependent on a cell tower, that user can hop through other users in dynamic, self roaming, self-healing rings. This is reason enough to make this technology available to first responders. But there is more: mobility, streaming audio and video, high-speed Internet, real-time asset awareness, geo-location, and in-building rescue support. All this , at speeds that rival cable modems and DSL. Combining 4G with ITS infrastructure makes both more robust. In 4G architectures, the network improves as the number of users increases. ITS offers the network lots of users, and therefore more robustness. Think of every light pole on a highway as a network element, a user that is acting as a router/repeater for first responders traveling on those highways. Think of every traffic light as a network element, ideally situated in the center of intersections with a 360-degree view of traffic. This is the power of the marriage between 4G networks and ITS.
10.3 Sensors in public vehicle
Putting a chemical-biological-nuclear (CBN) warning sensor on every government-owned vehicle instantly creates a mobile fleet that is the equivalent of an army of highly trained dogs. As these vehicles go about their daily duties of law enforcement, garbage collection, sewage and water maintenance, etc., municipalities get the added benefit of early detection of CBN agents. The sensors on the vehicles can talk to fixed devices mounted on light poles throughout the area, so positive detection can be reported in real time. And since 4G networks can include inherent geo-location without GPS, first responders will know where the vehicle is when it detects a CBN agent.
10.4 Cameras in traffic light
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 devices to support the mobile sensor application described above.
10.5 First responder route selection
Using fiber to backhaul cameras means that the intelligence collected flows one way: from the camera to the command center. Using a 4G network, those images can also be sent from the command center back out to the streets. Ambulances and fire trucks facing congestion can query various cameras to choose an alternate route. Police, stuck in traffic on major thoroughfares, can look ahead and make a decision as to whether it would be faster to stay on the main roads or exit to the side roads.
10.6 Traffic control during disasters
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.
11.FUTURE
We do have are good reasons for 4G development and a variety of current and evolving technologies to make 4G a reality. Highlighting the primary drivers for 4G wireless systems are cost, speed, flexibility, and universal access. Both service providers and users want to reduce the cost of wireless systems and the cost of wireless services. The less expensive the cost of the system, the more people who will want to own it. The high bandwidth requirements of upcoming streaming video necessitates a change in the business model the service providers use”from the dedicated channel per user model to one of a shared-use, as-packets-are-needed model. This will most likely be the model service providers use when 4G systems are commonplace (if not before).
Increased speed is a critical requirement for 4G communications systems. Data-rate increases of 10-50X over 3G systems will place streaming audio and video access into the hands of consumers who, with each wireless generation, demand a much richer set of wireless-system features. Power control will be critical since some services (such as streaming video) require much more power than do others (such as voice).
4G's flexibility will allow the integration of several different LAN and WAN technologies. This will let the user apply one 4G appliance, most likely a cell-phone/PDA hybrid, for many different tasks”telephony, Internet access, gaming, real-time information, and personal networking control, to name a few. A 4G appliance would be as important in home-networking applications as it would as a device to communicate with family, friends, and co-workers.
Finally, a 4G wireless phone would give a user the capability of global roaming and access”the ability to use a cell phone anywhere worldwide. At this point, the 4G wireless system would truly go into a "one size fits all" category, having a feature set that meets the needs of just about everyone.
12.CONCLUSION
The mobile technology though reached only at 2.5G now, 4G offers us to provide with a very efficient and reliable wireless communication system for seamless roaming over various network including internet which uses IP network. The 4G system will be implemented in the coming years which are a miracle in the field of communication engineering technology.
13.REFERENCES
1) Communications March 2002 Vol 40 No3
2) Communications October 2002 Vol 38 No 10
3) Communication Systems :- Simon Haykins
4) http://www.comsoc.org
5) http://www.crummer.rollins.edu/journal
6) http://www.techonline.com
7) http://www.ieee.org

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02-02-2010, 10:21 AM
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INTRODUCTION
4G is the short term for fourth-generation wireless.It is still a research lab standard , the stage of broadband mobile communications that will supercede the third generation (3G). it is expected that end-to-end IP and high-quality streaming video will be among 4G's distinguishing features.
A 4G system will be able to provide a comprehensive IP solution where voice , data and streamed multimedia can be given to the users on Anytime Anywhere basis and higher data rates than the previous generations.
It will be a fully IP based integrated system capable of providing between 100 Mbps to 1 Gbps in both indoor and outdoor with premium quality and high security.
It is going to be launched in the year 2010.

OBJECTIVE

4G is being developed to accommodate the Quality of Service (QOS) and rate requirements set by forth coming applications like
1. MMS (Multimedia Messaging Service)
2. Wireless Broadband Service
3. Video Chat
4. Mobile TV
5. Digital Video Broadcasting
6. High Network Capacity
7. Data Rate of 100 Mbps for mobile and 1 Gbps while stationary .
8. Smooth handoff across heterogenous network..
9. Seamless Connectivity and Global Roaming across multiple networks
Time-line from 1G to 4G and beyond:

The first generation, 1G wireless mobile communication systems, was introduced in the early 1980s. 1G wireless was analog and supported the first generation of analog cell phones with the speeds up to 2.4kbps.
The second generation, 2G system, fielded in the late 1980s.It was planned mainly for voice transmission with digital signal and the speeds up to 64kbps.
The third generation, 3G wireless system also called UMTS (Universal Mobile Telecommunications Standard). , was developed in the late 1990s .3G is not only provided the transmission speeds from 125kbps to 2Mbps, but also included many services, such as global roaming, superior voice and video quality.
The fourth generation (4G) is a conceptual framework just raised in 2002. The speeds of 4G can theoretically be promised up to 1Gbps. The beyond will be 5G with incredible transmission speed with no limitation for access and zone size
APPLIICATIONS

The applications of 4G are called KILLER APPLICATIONs as it is going to bring to revolution in the internet world.
-- High Speed Data Rate due to which a movie
can be downloaded in 2 to 3 minutes.
-- More Security
-- Video Conferencing
-- Higher Bandwidth
-- Global Roaming
ADVANTAGES Of 4G


High Speed:“ Data Rate of 100 Mbps for mobile and 1 Gbps while stationary
Global Standard:-4G will be a global standard that provides global mobility and service portability so that service provider will no longer be limited by single-system.
Low cost:“ access technologies, services and applications can unlimitedly be run through wireless backbone over wire-line backbone using IP address.
FUTURE OF 4G:5G (completed WWWW:
World Wide Wireless Web):

The idea of WWWW, World Wide Wireless Web, is started from 4G technologies. The following evolution will based on 4G and completed its idea to form a REAL wireless world. Thus, 5G should make an important difference and add more services and benefit to the world over 4G; 5G should be a more intelligent technology that interconnects the entire world without limits

CONCLUSION

As the history of mobile communications shows, attempts have been made to reduce a number of technologies to a single global standard.
4G seems to be a very promising generation of wireless communication that will change the peopleâ„¢s life in the wireless world.
4G is expected to be launched by 2010 and the world is looking forward for the most intelligent technology that would connect the entire globe.

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02-04-2010, 07:38 PM
Post: #5
RE: 4g wireless systems seminar
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