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 34

A Seminar Report


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


Page 2 of 34

A Seminar Report


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


Page 3 of 34

A Seminar Report


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-to4g.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.


Page 4 of 34

A Seminar Report

•


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..


Page 5 of 34

A Seminar Report


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


Page 6 of 34

A Seminar Report


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.


Page 7 of 34

A Seminar Report


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


Page 8 of 34

A Seminar Report


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


Page 9 of 34

A Seminar Report


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, fourthgeneration 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


Page 10 of 34

A Seminar Report


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

•

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


Page 11 of 34

A Seminar Report

•


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

Fig 3.1: 4G vision 2010


Page 12 of 34

A Seminar Report


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 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.


Page 13 of 34

A Seminar Report


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, highspeed information services, and entertainment broadcast services. Figure 1 illustrates elements and techniques to support the adaptability of the 4G domain.

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


Page 14 of 34

A Seminar Report


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


Page 15 of 34

A Seminar Report


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


Page 16 of 34

A Seminar Report


TABLE 1 Summary of the different 4G research challenges Aim Mobile Terminals and Users Multistandard/Multimode User Terminals

Automatic Network Tracking and Selection

Mobile Services Personal and Session Mobility

Streaming multimedia based services:

Multioperator-oriented intelligent billing system

Mobile and Wireless Access Networks Seamless Terminal


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

A roaming user in a heterogeneous environment should be able to automatically track and select the available underlying wireless network. In each communication session for a particular service the most appropriate underlying network should be chosen. Provision of personalized services through different personalized operating environments to the same address. To provide very high speed (streaming) video applications ensuring high QoS and bandwidth usability.

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.

Users should be able to roam

Vitally important challenges and problems

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

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. 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. 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.

Maintaining high data rate, best

Page 17 of 34

A Seminar Report

Mobility management


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

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

Integration and Interoperability of diverse networks

QoS Maintenance

Seamless integration and interworking of the multiple heterogeneous existing and new wireless access technologies to provide unhampered connectivity, fully broadband access, unhampered global roaming, perfect QoS and user controlled services. Unaffected QoS should be provided between the end users and end-to-end services.

Dependability

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

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. To implement intelligent packet

Routing


management, challenges like reducing call droppings and disruptions, reducing handover time, and optimizing effective call completion time need more attention. 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. 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. 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 4G networks. Stronger levels of protection is needed against eavesdropping, malicious calls, and service denials. Adaptive and lightweight security mechanisms should be implemented. Lowest Power Consumption

Page 18 of 34

A Seminar Report

Protocol Requirements

Communication Challenges Enhancing spectrum efficiency and channel capacity along with ubiquitous coverage.


and call routing techniques enhancing system performance.

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.

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.

To enhance spectral efficiency and channel capacity with wide area coverage providing costeffective 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, UltraWideband (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).


Page 19 of 34

A Seminar Report


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.


Page 20 of 34

A Seminar Report

Challenges in the Migration to 4G 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.


Page 21 of 34

A Seminar Report


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


Page 22 of 34

A Seminar Report


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


Page 23 of 34

A Seminar Report


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:


Page 24 of 34

A Seminar Report


•

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


Page 25 of 34

A Seminar Report


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.


Page 26 of 34

A Seminar Report


•

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


Page 27 of 34

A Seminar Report


•

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


Page 28 of 34

A Seminar Report


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


Page 29 of 34

A Seminar Report


systems to maximise the use of spectrum and balance the load. Given the degree of cooperation 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).


Page 30 of 34

A Seminar Report


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.


Page 31 of 34

A Seminar Report


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.


Page 32 of 34

A Seminar Report


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, “4thgeneration 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, 1215May,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


Page 33 of 34

A Seminar Report


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, , 711.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-to4g.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


Page 34 of 34

seminar report

Recommend Documents