seminar report

A Seminar Report Challenges in the Migration to 4G

Chapter 1

INTRODUCTION

1.1 Introduction

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.

The mobile communication generations has traversed a long way through

different phases of evolution since its birth early in the 1970s. the steady global boom in

the number of mobile users each year has periodically spurned the development of more

and more sophisticated technologies trying to strike the right chord primarily in terms of

provision of seamless global roaming, quality services and

high data rate. today numerous different generation technologies with their individual

pros and cons are existing globally. the coming era of 4g systems is foreseeing a potential

smooth merger of all these heterogeneous technologies with a natural progression to

support seamless cost-effective high data rate global roaming, efficient personalized

services, typical user-centric integrated service model, high Qos(quality of service) and

overall stable system performance. However, every step in such technological

advancements presents huge research challenges. this article aims to focus upon some of

these potential challenges along with different proposed feasible and non-feasible

solutions in the areas of mobile terminals and users, mobile services, mobile and wireless

BRECW, ECE Dept 2006- 10 Page 1 of 35


access networks, and communication, in order to give an in-depth view of the next-

generation communication systems.

1.2 Aim of the Seminar

Due to the increase in demand for speed, multimedia support and other resources,

the wireless world is looking forward for a new generation technology to replace the third

generation. This is where the fourth generation wireless communication comes into play.

4G wireless communication is expected to provide better speed, high capacity, lower cost

and IP based services. The main aim of 4G wireless is to replace the current core

technology with a single universal technology based on IP. Yet there are several

challenges that inhibits the progress of 4G and researchers throughout the world are

contributing their ideas to solve these challenges. This project deals with understanding

the features and challenges for 4G.

With the rapid development of wireless communication networks, it is expected

that fourth-generation mobile systems will be launched within decades. 4G mobile

systems focus on seamlessly integrating the existing wireless technologies including

GSM, wireless LAN, and Bluetooth. This contrasts with 3G, which merely focuses on

developing new standards and hardware. 4G systems supports comprehensive and

personalized services, providing stable system performance and quality service.

However, migrating current systems to 4G presents enormous challenges. In this article,

these challenges are discussed under the headings of networks and services, software

systems and wireless access.

Recent activity in 4G (fourth generation) mobile communication systems has

steeped the race in its implementation at the earliest. 4G wireless being an upcoming

standard witnesses burgeoning interest amongst researchers and vendor. It is being

designed to allow seamless integration and communication between wireless devices

across diverse wireless standards as well as broadband networks wirelessly. Access to

different radio technologies is facilitated due to IP-based-4G mobile communication

system connecting the user. This paper attempts to make an assessment in development,



transition, and roadmap for fourth generation mobile communication system with a

perspective of wireless convergence domain and future research issues.

1.3 Motivation of Seminar

The wireless communication filed is a very fast growing area with the number of

users and their demand for better resources increasing day by day. The R&D departments

of many companies are working on a future technology that can meet these demands at a

lower cost.3G is necessary but not sufficient for the demands today. So the world is

taking its leap towards the fourth generation wireless communication that promises to

bring an end to most of the problems faced. 4G wireless is expected to be launched by

2010, but there are numerous challenges faced by researchers in achieving the desired

features. Most of the ongoing researches are in the area of distributed computing, mobile

agents, multimedia support etc. Some other research area is to improve the Quality of

Service from the viewpoint of both the user and service providers. 4G wireless

infrastructures are expected to be deployed in an environment where many other types of

wireless and wired communication systems already exist.

1.4 Literature Survey

To fulfill the objectives of the seminar, understanding the concept of 4G is very

essential. Several standard books were referred.1. B G Evans & K Baughan, Visions of

4G, IEE Electronics and Communications engineering Journal, Autumn/Winter 2000.2. S

Y Hui & K H Yeung, Challenges in the Migration to 4G Mobile Systems, IEEE

Commuications, vol 41, no 12, Dec 2003, pp 54-59. 3.R Eijk, J Brok, J Bemmel & B

Busropan, Access Network selection in a 4G Environment and the Roles of Terminal and

Service Platform, Project: 4GPLUS, Wireless World Research Forum. 4.M Calisti, T

Lozza & D Greenwood, An Agent- Based Middleware for Adaptive Roaming in Wireless

Networks, Workshop on Agents for Ubiquitous Computing, AAMAS 2004, 20 July

2004, New York, USA. 5.K Murray, R Mathur & D Pesch, Network Access and

Handover Control in Heterogeneous Wireless Networks for Smart Apace Environments,

1st International Workshop on Managing Ubiquitous Communications and Services

(MUCS), Dec 11, 2003, Waterford, Ireland. 6.F Daneshgaran, M Laddamoda & M



Mondin, On the Reconfigurability of a Software Radio Terminal for Supporting the Third

and Fourth generation Wireless Standards, IEEE International Conference on Third

Generation Wireless and Beyond, June 2001, San Francisco. 7.T H Le & A H Aghvami,

Performance of an Accessing and Allocation Scheme for the Download Channel in

Software Radio, Proc IEEE Wireless Commun and Net Conf, vol 2, pp 517-21, 2000.

To get exposure to the latest ongoing developments, to achieve the said objectives and to

procure the necessary information the following websites were referred

1) http://www.mobileinfo.com/3G/4GVision&Technologies.htm .

2) http://nextelonline.nextel.com/en/stores/popups/4G_coverage_popup.shtml

3) http://seminarsandproject.blogspot.com/2009/06/challenges-in-migration-to-

4g.html

4) http://4g-wirelessevolution.tmcnet.com/conference/east-10/default.htm

5) http://en.wikipedia.org/wiki/4G

6) http://4g-wirelessevolution.tmcnet.com/

1.5 Applications

Virtual Presence : This means that 4G provides user services at all times, even if

the user is off-site.

Virtual navigation : 4G provides users with virtual navigation through which a

user can access a database of the streets, buildings etc of large cities. This requires

high speed data transmission.

Tele-Medicine : 4G will support remote health monitoring of patients. A user need

not go to the hospital and can get videoconference assistance for a doctor at

anytime and anywhere.

Tele-geo processing applications : This is a combination of GIS (Geographical

Information System) and GPS (Global Positioning System) in which a user can

get the location by querying.

Crisis management : Natural disasters can cause break down in communication

systems. In today’s world it might take days or weeks to restore the system. But in

4G it is expected to restore such crisis issues in a few hours.


http://4g-wirelessevolution.tmcnet.com/

http://en.wikipedia.org/wiki/4G

http://4g-wirelessevolution.tmcnet.com/conference/east-10/default.htm

http://seminarsandproject.blogspot.com/2009/06/challenges-in-migration-to-4g.html


http://nextelonline.nextel.com/en/stores/popups/4G_coverage_popup.shtml

http://www.mobileinfo.com/3G/4GVision&Technologies.htm


Education : For people who are interested in life long education, 4G provides a

good opportunity. People anywhere in the world can continue their education

online in a cost effective manner.

1.6 Organization of the Seminar Report

This paper is organized as follows. Chapter 1 provides information such as aim of

the seminar, motivation, literature survey and applications. Chapter 2 provides a brief

review of the previous generations, limitations of 3G, problems of 4G. Chapter 3 gives

the information about the desired features, objectives and the general view of 4G.

Chapter 4 provides a brief review of the research challenges faced by 4G. and finally

chapter 5 gives the conclusion. This paper is divided into four sections: introduction,

history, features, overview of the potential research challenges and conclusions..



Chapter 2

HISTORY

2.1 Brief History of Generations

The history and evolution of mobile service from the 1G (first generation) to

fourth generation are discussed in this section. Table 1 presents a short history of mobile

telephone technologies. This 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), mainly in

Europe; TDMA (time division multiple access) (IS-54/IS-136) in the U.S.; PDC

(personal digital cellular) in Japan; and CDMA (code division multiple access) (IS-95),

another U.S. system. 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 1990s, two organizations worked to define 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. Unfortunately, the two groups could

not reconcile their differences, and this decade will see the introduction of two mobile

standards for 3G. In addition, China is on the verge of implementing a third 3G

system. 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.

First Generation: 1G was based on analog technology and basically intended for analog

phones. It was launched in the early 1980s. It introduced the first basic framework for

mobile communications like the basic architecture, frequency multiplexing, roaming

concept etc. Access technology used was AMPS (Advances Mobile Phone Service).

Second Generation: 2G was a revolution that marked the switching of mobile

communication technology from analog to digital. It was introduced in the late 1980s and

it adopted digital signal processing techniques. GSM was one of the main attractive sides

of 2G and it introduced the concept of SIM (Subscriber Identity Module) cards. Main

access technologies were CDMA (Code Division Multiple Access) and GSM (Global

System for Mobile Communication).

2.5 Generation: 2.5 G was basically an extension of 2G with packet switching

incorporated to 2G. It implemented hybrid communication which connected the internet

to mobile communications.

Third Generation: The basic idea of 3G is to deploy new systems with new services

instead of just provide higher bandwidth and data rate. Support for multimedia

transmission is another striking feature of 3G. It employs both circuit switching and

packet switching strategies. The main access technologies are CDMA (Code Division

Multiple Access), WCDMA (Wideband CDMA), and TS- SDMA (Time division

Synchronous CDMA).

2.2 Limitations of 3G

4G is being developed to accommodate the QoS and rate requirements set by

forthcoming applications like wireless broadband access, Multimedia Messaging Service

(MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB),

minimal services like voice and data, and other services that utilize bandwidth.


http://en.wikipedia.org/wiki/Digital_Video_Broadcasting

http://en.wikipedia.org/wiki/High-definition_television

http://en.wikipedia.org/wiki/Mobile_TV

http://en.wikipedia.org/wiki/Videoconferencing

http://en.wikipedia.org/wiki/Multimedia_Messaging_Service

http://en.wikipedia.org/wiki/Quality_of_service


The 4G working group has defined the following as objectives of the 4G wireless

communication standard:

A spectrally efficient system (in bits/s/Hz and bits/s/Hz/site).

High network capacity: more simultaneous users per cell.

A nominal data rate of 100 Mbit/s while the client physically moves at high

speeds relative to the station, and 1 Gbit/s while client and station are in relatively

fixed positions as defined by the ITU-R.

A data rate of at least 100 Mbit/s between any two points in the world.

Smooth handoff across heterogeneous networks.

Seamless connectivity and global roaming across multiple networks.

High quality of service for next generation multimedia support (real time audio,

high speed data, HDTV video content, mobile TV, etc).

Interoperability with existing wireless standards and

An all IP, packet switched network.

In summary, the 4G system should dynamically share and utilize network resources to

meet the minimal requirements of all the 4G enabled users.

2.3 Problems with the Current System

One may then wonder why ubiquitous, high-speed wireless is not already

available. After all, wireless providers are already moving in the direction of expanding

the bandwidth of their cellular networks. Almost all of the major cell phone networks

already provide data services beyond that oared in standard cell phones, as illustrated in

Table 1.

Table 2.1: Cellular Providers and Services


http://en.wikipedia.org/wiki/Packet_switched

http://en.wikipedia.org/wiki/Roaming

http://en.wikipedia.org/wiki/Handoff

http://en.wikipedia.org/wiki/ITU-R

http://en.wikipedia.org/wiki/Spectral_efficiency


Unfortunately, the current cellular network does not have the available bandwidth

necessary to handle data services well. Not only is data transfer slow — at the speed of

analog modems — but the bandwidth that is available is not allocated efficiently for data.

Figure 2.1: Cellular Provider System Upgrades

Data transfer tends to come in bursts rather than in the constant stream of voice

data. Cellular providers are continuing to upgrade their networks in order to meet this

higher demand by switching to different protocols that allow for faster access speeds and

more efficient transfers. These are collectively referred to as third generation, or 3G,

services. However, the way in which the companies are developing their networks is

problematic — all are currently preceding in different directions with their technology

improvements. Figure 1 illustrates the different technologies that are currently in use, and

which technologies the providers plan to use.

Although most technologies are similar, they are not all using the same protocol.

In Addition, 3G systems still have inherent laws. They are not well-designed for data;

they are improvements on a protocol that was originally designed for voice. Thus, they

are inefficient with their use of the available spectrum bandwidth. A data-centered

protocol is needed. If one were to create two identical marketplaces in which cellular

providers used 3G and 4G respectively, the improvements in 4G would be easy



to see.

Speaking on the topic of 3G, one of the worlds leading authorities on mobile

communications, William C.Y. Lee, states that 3G would be “a patched up system that

could be inefficient”, and it would be best if the industry would leapfrog over 3G wireless

technology, and prepare for 4G (Christian ).

4G protocols use spectrum up to 3 times as efficiently as 3G systems, have better

ways of handling dynamic load changes (such as additional cellular users entering a

particular cell), and create more bandwidth than 3G systems. Most importantly, fourth-

generation systems will draw more users by using standard network protocols, which will

be discussed later, to connect to the Internet. This will allow simple and transparent

connectivity



Chapter 3

FEATURES OF 4G

3.1 Objectives

4G is being developed to accommodate the QoS and rate requirements set by

forthcoming applications like wireless broadband access, Multimedia Messaging Service

(MMS), video chat, mobile TV, HDTV content, Digital Video Broadcasting (DVB),

minimal services like voice and data, and other services that utilize bandwidth.

The 4G working group has defined the following as objectives of the 4G wireless

communication standard:

A spectrally efficient system (in bits/s/Hz and bits/s/Hz/site)

High network capacity: more simultaneous users per cell


http://en.wikipedia.org/wiki/Spectral_efficiency

http://en.wikipedia.org/wiki/Digital_Video_Broadcasting

http://en.wikipedia.org/wiki/High-definition_television

http://en.wikipedia.org/wiki/Mobile_TV

http://en.wikipedia.org/wiki/Videoconferencing

http://en.wikipedia.org/wiki/Multimedia_Messaging_Service


A nominal data rate of 100 Mbit/s while the client physically moves at high

speeds relative to the station, and 1 Gbit/s while client and station are in relatively

fixed positions as defined by the ITU-R

A data rate of at least 100 Mbit/s between any two points in the world

Smooth handoff across heterogeneous networks

Seamless connectivity and global roaming across multiple networks

High quality of service for next generation multimedia support (real time audio,

high speed data, HDTV video content, mobile TV, etc)

Interoperability with existing wireless standards, and

An all IP, packet switched network.

In summary, the 4G system should dynamically share and utilize network resources to

meet the minimal requirements of all the 4G enabled users.

3.2 Migration to Future

These limitations and drawbacks have generated the requirement for an universal

framework encompassing all the existing heterogeneous wired and wireless systems in

use. This IPv6-based potential 4G framework, commonly described as MAGIC [3]

(Mobile multimedia, Anytime anywhere access, Global mobility support, Integrated

wireless solution and Customized personal service), would be highly dynamic and

significantly handle the limitations of 3G systems. So, consolidated solutions that can

seamlessly operate on the multiple, diverse networks migrating to the 4G environment

fulfilling the plethora of next generation dream visualizations on implementing a

transparent open wireless architecture (OWA), should be imperatively designed. This

obviously invites new challenges on every step and researchers worldwide face an uphill

task of designing suitable solutions. Figure 1, shows such a 4G vision


http://en.wikipedia.org/wiki/Packet_switched

http://en.wikipedia.org/wiki/Roaming

http://en.wikipedia.org/wiki/Handoff

http://en.wikipedia.org/wiki/ITU-R


Fig 3.1: 4G vision 2010

3.3 Desired Features

High usability and global roaming: The end user terminals should be compatible with

any technology, at any time, anywhere in the world. The basic idea is that the user should

be able to take his mobile to any place, for example, from a place that uses CDMA to

another place that employs GSM.

Multimedia support: The user should be able to receive high data rate multimedia

services. This demands higher bandwidth and higher data rate.

Personalization: This means that any type of person should be able to access the service.

The service providers should be able to provide customized services to different type of

users. According to the members of the 4G working group, the infrastructure and the

terminals of 4G will have almost all the standards from 2G to 4G implemented. Although

legacy systems are in place to adopt existing users, the infrastructure for 4G will be only

packet-based (all-IP). Some proposals suggest having an open Internet platform.

Technologies considered to be early 4G include: Flash-OFDM, the 802.16e mobile

version of WiMax, and HC-SDMA. 3GPP Long Term Evolution may reach the market


http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution

http://en.wikipedia.org/wiki/WiMax

http://en.wikipedia.org/wiki/Flash-OFDM


1–2 years after Mobile WiMax is released. An even higher speed version of WiMax is the

IEEE 802.16m specification. LTE Advanced will be the later evolution of the 3GPP LTE

standard.

3.4 4G General View

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. Figure 1 illustrates

elements and techniques to support the adaptability of the 4G domain.


http://en.wikipedia.org/wiki/LTE_Advanced

http://en.wikipedia.org/wiki/IEEE_802.16


Fig 3.2 4G Vision

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. elements of the

.

Fig 3.3 : Key Elements of 4G Vision

Chapter 4

4G RESEARCH CHALLENGES

4.1 Main Challenges



To achieve the desired features listed above researches have to solve some of the

main challenges that 4G is facing. The main challenges are described below

Multimode user terminals: In order to access different kinds of services and technologies,

the user terminals should be able to configure themselves in different modes. This

eliminates the need of multiple terminals. Adaptive techniques like smart

antennas and software radio have been proposed for achieving terminal mobility.

Wireless system discovery and selection: The main idea behind this is the user terminal

should be able to select the desired wireless system. The system could be LAN, GPS,

GSM etc. One proposed solution for this is to use software radio approach where the

terminal scans for the best available network and then it downloads the required software

and configure themselves o access the particular network.

Terminal Mobility: This is one of the biggest issues the researchers are facing. Terminal

mobility allows the user to roam across different geographical areas that uses different

technologies. There are two important issues related to terminal mobility. One is location

management where the system has to locate the position of the mobile for providing

service. Another important issue is hand off management. In the traditional mobile

systems only horizontal hand off has to be performed where as in 4G systems both

horizontal and vertical hand off should be performed. As shown in figure 1, horizontal

hand off is performed when a mobile movies from one cell to another and vertical

handoff is performed when a mobile moves between two wireless systems.

Fig4.1: Handoff Mechanisms

Personal mobility: Personal mobility deals with the mobility of the user rather than the

user terminals. The idea behind this is, no matter where the user is located and what

device he is using, he should be able to access his messages.



Security and privacy: The existing security measures for wireless systems are inadequate

for 4G systems. The existing security systems are designed for specific services. This

does not provide flexibility for the users and as flexibility is one of the main concerns for

4G, new security systems has to be introduced.

Fault tolerance: As we all know, fault tolerant systems are becoming more popular

throughout the world. The existing wireless system structure has a tree like topology and

hence if one of the components suffers damage the whole system goes down. This is not

desirable in case of 4G. Hence one of the main issues is to design a fault tolerant system

for 4G.

Billing System : 3G mostly follows a flat rate billing system based where the user is

charged just by a single operator for his usage according to call duration, transferred data

etc. But in 4G wireless systems, the user might switch between different service

providers and may use different services. In this case, it is hard for both the users and

service providers to deal with separate bills. Hence the operators have to design a billing

architecture that provides a single bill to the user for all the services he has used.

Moreover the bill should be fair to all kinds of users.

Table 4.1:The different potential challenges

TABLE 1 Summary of the different 4G research challenges

Aim Vitally important challenges and problems

Mobile Terminals and Users

Multistandard/Multimode User Terminals

A single wireless user terminal should be designed, which can automatically operate in different heterogeneous access networks.

Problems related to high cost, limitations in terminal size, high power consumption, high circuit complexity, and unimproved analog-to-digital converter (ADC) performance in software defined radio (SDR)-based implementations.The different software downloading schemes related to reconfigurable terminals have got their own problems.

Automatic Network Tracking and Selection

A roaming user in a heterogeneous environment should be able to automatically track and select the available underlying wireless network. In each

The different software downloading schemes related to reconfigurable terminals have got their own problems.



communication session for a particular service the most appropriate underlying network should be chosen.

Mobile Services

Personal and SessionMobility

Provision of personalized services through different personalized operating environments to the same address.

Confusions regarding the choice of either MIP or SIP as the core protocol and also whether the ideal framework be Network layer-based or Application layer-based.

Streaming multimedia based services:

To provide very high speed (streaming) video applications ensuring high QoS and bandwidth usability.

UDP suffers from acute congestion related problems, so TCP is gaining importance as the ideal transport layer protocol for video streaming. Opportunistic scheduling based video streaming needs more attention.

Multioperator-oriented intelligent billing system

Users subscribing to multiple service operators for multiple different services should ideally be charged a single bill covering all the different billing schemes involved. Users need not worry about the different billing schemes.

Designing new packet-switched oriented billing and accounting policies for 4G users. From customers and operators points of view handling issues like QoS dependant charging, real-time billing information support, interworking prepaid systems support and billing support to diverse service accesses as well as cost calculation flexibility, IP traffic billing support, instant discontinuation of service if any fraud is detected and correct maintenance of customer’s profile, are the real problems.

Mobile and Wireless Access Networks

Seamless Terminal Mobility management

Users should be able to roam freely and seamlessly across the various global geographic locations. Location and handoff managements should be done properly.

Maintaining high data rate, best possible QoS, reducing packet loss and signaling overhead are the primary challenges. The system throughput should be increased with low handover latency. In location management, issues like optimally handling diverse user calling and mobile patterns, and better inter-network location coordination should be handled properly. In handover

TABLE 1 (Contd...)

Aim Vitally important challenges and problems

Mobile Terminals and Users

management, challenges like



reducing call droppings and disruptions, reducing handover time, and optimizing effective call completion time need more attention.

Integration and Interoperability of diverse networks

Seamless integration and interworking of the multiple heterogeneous existing and new wireless access technologies to provide unhampered connectivity, fully broadband access, unhampered globalroaming, perfect QoS and user controlled services.

Problems owing to diverse nature of the constituent access technologies in terms of varying bit rates, bandwidth allocation, channel characteristics, fault-tolerance levels and handoff management mechanisms are the key ones.

QoS Maintenance Unaffected QoS should be provided between the end users and end-to-end services.

Significant overhead problems still persist in different QoS schemes like traffic control, dynamic resource reservation and QoS renegotiation. Ideal mixing of packet level and non-packetlevel QoS mechanisms should be done.

Dependability To ensure fully fault-tolerant and survivable 4G systems.

Ideal fault discovery, notification service & recovery schemes should be designed to minimize failures and their potential impacts on any level of the hierarchical topologies of the 4Gnetworks.

Security aspects Stronger end-to-end security services are needed to get credentials of the communicating parties (residing in different environment) authenticated without even knowing each other.

Stronger levels of protection is needed against eavesdropping, malicious calls, and service denials. Adaptive and lightweight security mechanisms should be implemented.

Routing To implement intelligent packet and callrouting techniques enhancing system performance.

Lowest Power Consumption and best QoS are the key attributes to be addressed while defining a “best path” routing technique. Efficient global and ad-hoc routing techniques, and semantic routing based content delivery techniques need to implemented. Mesh network routing techniques are also inadequately addressed.

Protocol Requirements

Unified networking protocol stack and vertical protocol integration mechanisms adapting to the 4G constituent networks requirements should be designed.

Efficient 4G mobile network and security protocols capable of dynamically adopting to variant channel conditions and security requirements should be implemented. New ad-hoc protocols for self-organization



to be designed.

Communication Challenges

Enhancing spectrum efficiency and channel capacity along with ubiquitous coverage.

To enhance spectral efficiency and channel capacity with wide area coverage providing cost-effective very high data rate. Increasing bandwidth usability and minimizing multi-path effects.

Handling the different drawbacks related to Orthogonal Frequency Division Multiplexing (OFDM)-based air interfaces, Ultra-Wideband (UWB) radio transmission technology (UWBRT) and smart antenna technology.

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.

4.2 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).



Fig 4.2: Seamless connection of networks

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 optimization for different applications and in different

radio environments. In this depiction we need to provide global roaming across all layers.

Fig 4.3: Vertical hierarchical networks



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.

Fig 4.4: Reconfiguration of mobile system

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 ‘mobile ad hoc network’ (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).

Fig 4.5: An integrated ad hoc wireless system



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 ‘network of mobile

nodes’ 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 ‘guaranteed’ 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.

4.3 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.

4.4 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 signaling 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

optimize 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 optimize 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

utilization 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,

equalization/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 equalizers 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 synchronization. The

choice of the air interface’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 organizing 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 characterizations.

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 mega cell,

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 under laid Pico cells 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).



Fig 4.6 : HAPS providing integrated coverage

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

VCE’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.



Chapter 5

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.

4G seems to be a very promising generation of wireless communication that will

change the people’s life in the wireless world. There are many striking attractive features

proposed for 4G which ensures a very high data rate, global roaming etc. New ideas are

being introduced by researchers throughout the world, but new ideas introduce new

challenges. There are several issues yet to be solved like incorporating the mobile world

to the IP based core network, efficient billing system, smooth hand off mechanisms etc.

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.



REFERENCES

Text Books

1) J. Z. Sun, J. Sauvola, D. Howie, “Features in future: 4G visions from a technical

perspective,” Global Telecommunications Conference, 2001.

GLOBECOM'01,IEEE, Volume:6, 25-29,Nov.2001, pp:3533 - 3537 vol.6

2) S. Y. Hui, K. H. Yeung, “ Challenges in the migration to 4G mobile systems,”

Communications Magazine, IEEE , Volume: 41 , Issue: 12 , Dec. 2003, pp:54 –

59

3) A. Bria, F. Gessler, O. Queseth, R. Stridh, M. Unbehaun, J. Wu, J. Zander, “4th-

generation wireless infrastructures: scenarios and research challenges,” Personal

Communications, IEEE [see also IEEE Wireless Communications], Volume:8,

Issue:6, Dec.2001, pp:25 - 31

4) U. Varshney, R. Jain, “Issues in emerging 4G wireless networks,” Computer,

Volume:34, Issue:6, June2001, pp:94 - 96

5) K. R. Santhi, V. K. Srivastava, G. SenthilKumaran, A. Butare, “Goals of true

broad band's wireless next wave (4G-5G),” Vehicular Technology Conference,

2003. VTC 2003-Fall. 2003 IEEE 58th , Volume: 4 , 6-9 Oct. 2003, Pages:2317 -

2321 Vol.4

6) L. Zhen, Z. Wenan, S. Junde, H. Chunping, “Consideration and research issues

for the future generation of mobile communication,” Electrical and Computer

Engineering, 2002. IEEE CCECE 2002. Canadian Conference on , Volume:3, 12-

15May,2002 , pp:1276 - 1281 vol.3

7) J. Hu, W. W. Lu, “Open wireless architecture - the core to 4G mobile

communications,” Communication Technology Proceedings, 2003. ICCT 2003.

International Conference on , Volume: 2 , 9-11 April 2003 pp:1337 - 1342 vol.2

8) N. Montavont, T. Noel, “Handover management for mobile nodes in IPv6

networks,” Communications Magazine, IEEE , Volume: 40 , Issue: 8 , Aug.2002,

Pages:38 – 43



9) S. Chatterjee, W. A. C Fernando, M. K.. Wasantha, “Adaptive modulation based

MC-CDMA systems for 4G wireless consumer applications,” Consumer

Electronics, IEEE Transactions on , Volume: 49 , Issue:4, Nov.2003, pp:995 –

1003

10) W. Zhou, X. Lu, J. Zhu, “M-ary MC-CDMA system for 4G,” Vehicular

Technology Conference, 2001. VTC 2001 Fall. IEEE VTS 54th , Volume: 4, , 7-

11.Oct.2001, pp:2234 - 2238 vol.4

11) B. G. Evans and K. Baughan, "Visions of 4G," Electronics and Communication

Engineering Journal, Dec. 2002..

12) H. Huomo, Nokia, "Fourth Generation Mobile," presented at ACTS Mobile

Summit99, Sorrento, Italy, June 1999.

13) J. M. Pereira, "Fourth Generation: Now, It Is Personal," Proceedings of the 11th

IEEE International Symposium on Personal, Indoor and Mobile Radio

Communications, London, UK, September 2000

14) Al-Muhtadi, J., D. Mickunas, and R. Campbell. “A lightweight reconfigurable

security mechanism for 3G/4G mobile devices.” IEEE Wireless Communications

9.2 (2002):60–65.

Websites

1) http://www.mobileinfo.com/3G/4GVision&Technologies.htm .

2) http://nextelonline.nextel.com/en/stores/popups/4G_coverage_popup.shtml

3) http://seminarsandproject.blogspot.com/2009/06/challenges-in-migration-to-

4g.html

4) http://4g-wirelessevolution.tmcnet.com/conference/east-10/default.htm

5) http://en.wikipedia.org/wiki/4G

6) http://4g-wirelessevolution.tmcnet.com

7) http://www.iec.org/online/tutorials/smart ant/topic01.html


http://www.iec.org/online/tutorials/smart%20ant/topic01.html

http://4g-wirelessevolution.tmcnet.com/

http://en.wikipedia.org/wiki/4G

http://4g-wirelessevolution.tmcnet.com/conference/east-10/default.htm



http://nextelonline.nextel.com/en/stores/popups/4G_coverage_popup.shtml

http://www.mobileinfo.com/3G/4GVision&Technologies.htm

seminar report

Documents

g wireless communication

g systems

g mobile systems

g mobile communication

generation mobile systems

generation systems

wireless world

wireless brecw