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4G TECHNOLOGY 2011
Acknowledgement
I feel immense pleasure in submitting this seminar report on “4G Technology”. The
valuable guidance of my teaching staff department made this study possible. They have
been a constant source of encouragement throughout the completion of this seminar.
I would sincerely like to thank to Mr. Satish Kumar for his help and support
during making this seminar report. This report would not have been successful without
the immense guidance and the valuable time that he has given me during my seminar
report development stages.
Charu Pandey
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ABSTRACT
The fourth generation of mobile networks will truly turn the current mobile phone
networks, in to end to end IP based networks, couple this with the arrival of IPv6, every device
in the world will have a unique IP address, which will allow full IP based communications
from a mobile device, right to the core of the internet, and back out again. If 4G is
implemented correctly, it will truly harmonize global roaming, super high speed connectivity,
and transparent end user performance on every mobile communications device in the world.
4G is set to deliver 100mbps to a roaming mobile device globally, and up to 1gbps to a
stationary device. With this
in mind, it allows for video conferencing, streaming picture perfect video and much more. It
won’t be just the phone networks that need to evolve, the increased traffic load on the internet
as a whole (imagine having 1 billion 100mb nodes attached to a network over night) will need
to expand, with faster backbones and oceanic links requiring major upgrade. 4G won’t happen
overnight, it is estimated that it will be implemented by 2012, and if done correctly, should
take off rather quickly. 4G networks i.e. Next Generation Networks (NGNs) are becoming fast
and very cost-effective solutions for those wanting an IP built high-speed data capacities in the
mobile network. Some possible standards for the 4G system are 802.20, WiMAX (802.16),
HSDPA, TDD UMTS, UMTS and future versions of UMTS. The design is that 4G will be
based on OFDM (Orthogonal Frequency Division Multiplexing), which is the key enabler of
4G technology. Other technological aspects of 4G are adaptive processing and smart antennas,
both of which will be used in 3G networks and enhance rates when used in with OFDM.
Currently 3G networks still send their data digitally over a single channel; OFDM is designed
to send data over hundreds of parallel streams, thus increasing the amount of information that
can be sent at a time over traditional CDMA networks.
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Table of Content
1. INTRODUCTION .......................................................................................................................................... 4
2. WHAT IS 4G? ............................................................................................................................................... 9
3. FEATURES ................................................................................................................................................. 13
4. WHAT IS NEEDED TO BUILD 4G NETWORKS OF FUTURE? ............................................................... 15
5. IMPLEMENTATION USING 4G ................................................................................................................ 16
6. ARCHITECTURES IN PROSPECTS .......................................................................................................... 18
6.1 End-to-end Service Architectures for 4G Mobile Systems:- .................................................................. 18
6.2
Middleware Architecture:-........................................................................................................... 19
6.3
Cellular Multi-hop Communications: Infrastructure-Based Relay Network Architecture:- .............. 19
6.4 Overlay network:- ............................................................................................................................. 21
7. A BASIC MODEL FOR 4G NETWORKS .................................................................................................. 23
8.TRANSMISSION.......................................................................................................................................... 25
9. WIRELESS TECHNOLOGIES USED IN 4G ............................................................................................ 27
9.1 Orthogonal Frequency Division Multiplexing: ..................................................................................... 28
9.2 Error Correcting: .............................................................................................................................. 30
9.3 Millimeter Wireless: .......................................................................................................................... 31
9.4 Long Term Power Prediction: ............................................................................................................ 31
9.5 Scheduling among Users: ................................................................................................................... 31
9.6 Adaptive modulation and power control: ............................................................................................. 32
10. 4G SOFTWARE ........................................................................................................................................ 34
10.1
10.2
10.3
10.4
Software Defined Radio .............................................................................................................. 34
Packet Layer .............................................................................................................................. 34
Packets ...................................................................................................................................... 35
Implementation of Packets .......................................................................................................... 37
11. 4G HARDWARE ....................................................................................................................................... 40
11.1
11.2
Ultra Wide Band Networks.......................................................................................................... 40
Smart Antennas .......................................................................................................................... 40
12. LIMITATIONS OF 3G AND DRIVERS FOR 4G ...................................................................................... 42
13. 4G VISIONS MAPPING TO RESEARCH TOPICS................................................................................... 45
14. RESEARCH CHALLENGES..................................................................................................................... 47
15. MOBILITY MANAGEMENT ..................................................................................................................... 52
16. QUALITY OF SERVICE (QOS):-.............................................................................................................. 53
17. SECURITY ................................................................................................................................................ 55
18. ADVANTAGES:- ...................................................................................................................................... 56
19. APPLICATIONS ....................................................................................................................................... 57
20. CONCLUSION ......................................................................................................................................... 59
21. REFERENCES .......................................................................................................................................... 60
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1. INTRODUCTION
4G (also known as Beyond 3G), an abbreviation for Fourth-Generation, is a
term used to describe the next complete evolution in wireless communications.
A 4G system will be able to provide a comprehensive IP solution where voice,
data and streamed multimedia can be given trousers on an "Anytime,
Anywhere" basis, and at higher data rates than previous generations.
The approaching 4G (fourth generation) mobile communication systems are
projected to solve still-remaining problems of 3G (third generation) systems
and to provide a wide variety of new services, from high-quality voice to
high-definition video to high-data-rate wireless channels. The term 4G
is used broadly to include several types of broadband wireless access
communication systems, not only cellular telephone systems. One of the terms
used to describe
4G is MAGIC-Mobile multimedia, anytime anywhere, Global mobility
support,
integrated-wireless solution, and customized personal service. As a
promise for the future, 4G systems, that is, cellular broadband wireless access
systems have been attracting much interest in
the mobile communication
arena. The 4G systems not only will support the next generation of
mobile service, but also will support the fixed wireless networks. Researchers
and vendors are expressing a growing interest in 4G wireless networks that
support global roaming across multiple wireless and mobile networks—for
example, from a
cellular network to a satellite-based network to a high-bandwidth
wireless LAN. With this feature, users will have access to different
services, increased coverage, the convenience of a single device, one bill
with reduced total access cost, and more reliable wireless access even with the
failure or loss of one or more networks. 4G networks will also feature IP
interoperability for seamless mobile Internet access and bit rates of 50 Mbps or
more.
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2. HISTORY
At the end of the 1940’s, the first radio telephone service was introduced, and was
designed to users in cars to the public land-line based telephone network. Then,
in the sixties, a system launched by Bell Systems, called IMTS, or, “Improve d
Mobile Telephone Service", brought quite a few improvements such as direct
dialing and more bandwidth. The very first analog systems were based upon IMTS
and were created in the late 60s and early 70s. The systems were called "cellular"
because large coverage areas were split into smaller areas or "cells", each cell is served
by a low power transmitter and receiver. The 1G or First Generation was an analog
system, and was developed in the seventies, 1G had two major improvements, this was
the invention of the microprocessor, and the digital transform of the control link
between the phone and the cell site. Advance mobile phone system (AMPS) was first
launched by the US and is a 1G mobile system. Based on FDMA, it allows users to
make voice calls in 1 country.
2G or Second Generation
2G first appeared around the end of the 1980’s, the 2G system digitized the voice
signal, as well as the control link. This new digital system gave a lot better quality and
much more capacity (i.e. more people could use their phones at the same time), all at a
lower cost to the end consumer. Based on TDMA, the first commercial network for
use by the public was the Global system for mobile communication (GSM).
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3G or Third Generation
3G systems promise faster communications services, entailing voice, fax and
Internet data transfer capabilities, the aim of 3G are to provide these services anytime,
anywhere throughout the globe, with seamless roaming between standards. ITU’s
IMT-2000 is a global standard for 3G and has opened new doors to enabling
innovative services and application for instance, multimedia entertainment, and
location-based services, as well as a whole lot more .In 2001,Japan saw the first
3G network launched. 3G technology supports around 144 Kbps, with high speed
movement, i.e. in a vehicle. 384Kbps locally, and upto 2Mbps for fixed stations, i.e. in
a building.
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Fig 1: - History of Mobile Networks
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2. What is 4G?
Fourth generation (4G) wireless was originally conceived by the Defense
Advanced Research Projects Agency (DARPA), the same organization that developed
the wired Internet. It is not surprising, then, that DARPA chose the same
distributed architecture for the wireless Internet that had proven so successful in the
wired Internet. Although experts and policymakers have yet to agree on all the aspects
of 4G wireless, two characteristics have emerged as all but certain components of 4G:
end-to-end Internet Protocol (IP), and peer-to-peer networking. An all IP network
makes sense because consumers will want to use the same data applications they are
used to in wired networks. A peer-to-peer network, where every device is both a
transceiver and a router/repeater for other devices in the network, eliminates this
spoke-and-hub weakness of cellular architectures, because the elimination of a single
node does not disable the network. The final definition of “4G” will have to include
something as simple as this: if a consumer can do it at home or in the office while
wired to the Internet, that consumer must be able to do it wirelessly in a fully
mobile environment.
Let’s define “4G” as “wireless ad hoc peer-to-peer networking.” 4G technology is
significant because users joining the network add mobile routers to the network
infrastructure. Because users carry much of the network with them, network
capacity and coverage is dynamically shifted to accommodate changing user patterns.
As people congregate and create pockets of high demand, they also create additional
routes for each other, thus enabling additional access to network capacity. Users will
automatically hop away from congested routes to less congested routes. This permits
the network to dynamically and automatically self-balance capacity, and increase
network utilization. What may not be obvious is that when user devices act as routers,
these devices are actually part of the network infrastructure. So instead of carriers
subsidizing the cost of user devices (e.g., handsets, PDAs, of laptop computers),
consumers actually subsidize and help deploy the network for the carrier. With a
cellular infrastructure, users contribute nothing to the network. They are just consumers
competing for resources. But in wireless ad hoc peer-to-peer networks, users
cooperate – rather than compete – for network resources.
Thus, as the service gains popularity and the number of user increases, service likewise
improves for all users. And there is also the 80/20 rule. With traditional wireless
networks, about 80% of the cost is for site acquisition and installation, and just 20% is
for the technology. Rising land and labor costs means installation costs tend to rise
over time, subjecting the service providers’ business models to some challenging
issues in the out years. With wireless peer-to-peer networking, however, about 80% of
the cost is the technology and only 20% is the installation. Because technology costs
tend to decline over time, a current viable business model should only become more
profitable over time. The devices will get cheaper, and service providers will reach
economies of scale sooner because they will be able to pass on the infrastructure
savings to consumers, which will further increase the rate of penetration. This new
generation of wireless is intended to complement and replace the 3G systems, perhaps
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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. 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 networks,
public to private; operator-driven broadband networks to personal areas; and ad hoc
networks. The 4G systems will interoperate With 2G and 3G systems, as well as with
digital(broadband) broadcasting systems. In addition, 4G systems will be fully IP-based
wireless Internet. This all-encompassing integrated perspective shows the broad range
of systems that the fourth generation intends to integrate, from satellite broadband to
high altitude platform to cellular 3G and 3G systems to WLL (wireless local loop) and
FWA(fixed wireless access) to WLAN (wireless local area network) and PAN
(personal area network), all with IP as the integrating mechanism. With 4G, a range of
new services and models will be available. These services and models need to be
further examined for their interface with the design of 4G systems.
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Fig 2: - 4G Mobile Communication
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4G Open Wireless Architecture
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3. FEATURES

Support for interactive multimedia, voice, streaming video, Internet, and
Other broadband services

IP based mobile system

High speed, high capacity, and low cost-per-bit

Global access, service portability, and scalable mobile services

Seamless switching, and a variety of Quality of Service-driven services

Better scheduling and call-admission-control techniques

Ad-hoc and multi-hop networks (the strict delay requirements of voice make
Multi-hop network service a difficult problem)
Better spectral efficiency


Seamless network of multiple protocols and air interfaces (since 4G will be
All-IP, look for 4G systems to be compatible with all common network
Technologies, including 802.11, WCDMA, Bluetooth, and Hyper LAN).

An infrastructure to handle pre-existing 3G systems along with other wireless
technologies, some of which are currently under development.
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4. What is needed to Build 4G Networks of Future?
A number of spectrum allocation decisions, spectrum standardization decisions, spectrum
availability decisions, technology innovations, component development, signal processing and
switching enhancements and inter-vendor cooperation have to take place before the vision of
4G will materialize. We think that 3G experiences - good or bad, technological or business will be useful in guiding the industry in this effort. We are bringing to the attention of
professionals in telecommunications industry following issues and problems that must be
analyzed and resolved:
* Lower Price Points Only Slightly Higher than Alternatives - The business visionaries
should do some economic modeling before they start 4G hype on the same lines as
3G hype. They should understand that 4G data applications like streaming video must
compete with very low cost wire-line applications. The users would pay only delta premium
(not a multiple) formost wireless applications.
* More Coordination among Spectrum Regulators around the World- Spectrum regulation
bodies must get involved in guiding the researchers by indicating which frequency band might
be used for 4G. FCC in USA must cooperate more actively with International bodies like ITU
and perhaps modify its hands-off policy in guiding the industry. When public interest, national
security interest and economic
interest
(inter-industry
ala
TV
versus
Telecommunications) are at stake, leadership must come from regulators. At appropriate time,
industry builds its own self-regulation mechanisms.
* More Academic Research: Universities must spend more effort in solving fundamental
problems in radio communications (especially multiband and wideband radios, intelligent
antennas and signal processing.
* Standardization of wireless networks in terms of modulation techniques, switching schemes
and roaming is an absolute necessity for 4G.
* A Voice-independent Business Justification Thinking: Business development and
technology executives should not bias their business models by using voice channels as
economic determinant for data applications. Voice has a built-in demand limit - data
applications do not.
* Integration Across Different Network Topologies: Network architects must base their
architecture on hybrid network concepts that integrates wireless wide area networks,
wireless LANS (IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.15 and IEEE 802.16,
Bluetooth with fiber-based Internet backbone. Broadband wireless networks must be a part
of this integrated network architecture.
* Non-disruptive Implementation: 4G must allow us to move from 3G to 4G.
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5. IMPLEMENTATION USING 4G
The goal of 4G is to replace the current proliferation of core mobile networks
with a single worldwide core network standard, based on IP for control, video, packet
data, and voice. This will provide uniform video, voice, and data services to the mobile
host, based entirely on IP.
The objective is to offer seamless multimedia services to users accessing an all IPbased infrastructure through heterogeneous access technologies. IP is assumed to
act as an adhesive for providing global connectivity
and
mobility
among
networks.
An all IP-based 4G wireless network has inherent advantages over its predecessors. It
is compatible with, and independent of the underlying radio access technology. An IP
wireless network replaces the old Signaling
System 7 (SS7) telecommunications protocol, which is considered massively
redundant. This is because SS7 signal transmission consumes a larger part of network
bandwidth even when there is no signaling traffic for the simple reason that it uses a
call setup mechanism to reserve bandwidth, rather time/frequency slots in the radio
waves. IP networks, on the other hand, are connectionless and use the slots only when
they have data to send. Hence there is optimum usage of the available bandwidth.
Today, wireless communications are heavily biased toward voice, even though studies
indicate that growth in wireless data traffic is rising exponentially relative to demand
for voice traffic. Because an all IP core layer is easily scalable, it is ideally suited to
meet this challenge. The goal is a merged data/voice/multimedia network.
IMPLEMENTATION DIAGRAM OF 4G
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6. Architectures in Prospects
6.1 End-to-end Service Architectures for 4G Mobile Systems:A characteristic of the transition towards 3G systems and beyond is that highly
integrated telecommunications service suppliers fail to provide effective economies of
scale. This is primarily due to deterioration of vertical integration scalability with
innovation speed up. Thus, the new rule for success in 4G telecommunications
markets will be to provide one part of the puzzle and to cooperate with other
suppliers to create the complete solutions that end customers require.
A direct consequence of these facts is that a radically new end-to-end service
architecture will emerge during the deployment of 3G mobile networks and will
became prominent as the operating model of choice for the Fourth Generation (4G)
Mobile Telecommunications Networks. This novel end-to-end service architecture is
inseparable from an equally radical transformation of the role of the
telecommunications network operator role in the new value chain of end service
provision. In fact, 4G systems will be organized not as monolithic structures deployed
by a single business entity, but rather as a dynamic confederation of multiple—
sometimes cooperating and sometimes competing—servi ce providers.
End-to-end service architectures should have the following desirable properties:
• Open service and resource allocation model.
• Open capability negotiation and pricing model .
• Trust management. Mechanisms for managing trust relationships among clients and
service providers, and between service providers, based on trusted third party
monitors.
• Collaborative service constellations.
• Service fault tolerance.
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6.2
Middleware Architecture:-
The service middleware is decomposed into three layers; i.e. user support layer,
service support layer and network support layer. The criterion for using a layered
approach is to reuse the existing subsystems in the traditional middleware. The
user support layer has autonomous agent aspects that traditional service
middleware lacks. It consists of 4 sub-systems:
‘Personalization’, ‘Adaptation’, ‘Community’ and ‘Coordination’, to provide
mechanisms for context awareness and support for communities and
coordination. Introduction of this functional layer enables the reduction of
unnecessary user interaction with the system and the provision of usercentric services realized by applying agent concepts, to support analysis
of the current context, personalization depending on the user’s situation, and
negotiation for service usage.
The middle layer, the service support layer, contains most functionality of
traditional middleware. The bottom layer, the network layer supports
connectivity for all-IP networks. The dynamic service delivery pattern defines a
powerful interaction model to negotiate the conditions of service delivery by
using three subsystems: ‘Discovery & Advertisement’, ‘Contract Notary’ and
‘Authentication & Authorization’.
6.3
Cellular
Multi-hop
Communications: Infrastructure-Based
Relay Network Architecture:-
It is clear that more fundamental enhancements are necessary for the very
ambitious throughput and coverage requirements of future networks.
Towards that end, in addition to advanced transmission techniques and antenna
technologies, some major modifications in the wireless network architecture
itself, which will enable effective distribution and collection of signals to and
from wireless users, are sought. The integration of “multi-hop” capability into
the conventional wireless networks is perhaps the most promising architectural
upgrade.
In a Multi-hop network, a signal from a source may reach its destination in
multiple hops (whenever necessary) through the use of “relays”. Since we are
here concerned with infrastructure-based networks, either the source or
destination is a common point in the network.
Base station (or, access point, in the context of WLANs).The potential
advantage of relaying is that it allows substituting a poor-quality (due to high
path loss) single-hop wireless link with a composite, two- or more hop,
better-quality link whenever possible. Relaying is not only efficient in
eliminating black spots throughout the coverage region, but more importantly, it
may extend the high data rate coverage range of a single BS; therefore
cost-effective high data rate coverage may be possible through the
augmentation of the relaying capability in conventional cellular networks.
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Advantages:• Property owners can install their own access points.
– Spreads infrastructure cost.
• Reduced network access operational cost.
– Backbone access through wireless.
– Wired access through DSL at aggregation points.
• Ad hoc-like characteristics:
– Access points configure into access network.
– Some access points may be moving (bus, train).
• Multi-hop also could reduce costs in heterogeneous 3G networks.
– 802.11 to GPRS for example.
Fig.: - Example of Heterogeneous Network Multihop Architecture
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6.4 Overlay network:In this architecture, a user accesses an overlay network consisting of several
universal access points. These UAPs in turn select a wireless network
based on availability, QoS specifications, and user defined choices. A UAP
performs protocol and frequency translation, content adaptation, and QoS negotiationrenegotiation on behalf of users. The overlay network, rather than the user or device,
performs handoffs as the user moves from one UAP to another. A UAP stores user,
network, and device information, capabilities, and preferences. Because UAPs can keep
track of the various resources a caller uses, this architecture supports single billing and
subscription.
Figure1. Possible 4G wireless network architectures.
(a) A multimode device lets the user, device, or network initiate handoff between
networks without the need for network modification or interworking devices.
(b) An overlay network—consisting of several universal access points (UAPs)
that store user, network, and device information—performs a handoff as the user
moves from one UAP to another.
(c) A device capable of automatically switching between networks is possible if
wireless networks can support a common protocol to access a satellite-based
network and another protocol for terrestrial networks.
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Fig : -Overlay Networks
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7. A Basic Model for 4G Networks
QoS, security and mobility can be viewed as three different, indispensable aspects in
4G networks; however all are related to network nodes involving the controlling or the
processing of IP packets for end-to-end flows between an MN and the CN. I show in
this section how we view the 4G network infrastructure.
Two Planes: Functional Decomposition
Noting that an IP network element (such as a router) comprises of numerous functional
components that cooperate to provide such desired service (such as, mobility, QoS
and/or AAA – Authentication, Authorization and Accounting), we identify these
components in the SeaSoS architecture into two planes, namely the control plane and
the data plane. Fig. 5 illustrates this method of flexible functional composition in
4G networks. As we are mainly concerned with network elements effectively at the
network layer, we do not show a whole end-to-end communication picture through a
whole OSI or TCP/IP stack. The control plane performs control related actions
such as AAA, MIP registration, QoS signaling, installation/maintenance of
traffic selectors and security associations, etc., while the data plane is responsible for
data traffic behaviors (such as classification, scheduling and forwarding) for end-to-end
traffic flows. Some components located in the control plane interact, through
installing and maintaining certain control states for data plane, with data plane
components in some network elements, such as access routers (ARs), IntServ
nodes or DiffServ edge routers.
However, not all control plane components need to exist in all network elements, and
also not all network elements (e.g., AAA server) are involved with data plane
functionalities. I refer these cases as path-decoupled control and other cases as path
coupled control. We argue the separation and coordination of control plane and
data plane is critical for seamless mobility with QoS and security support in 4G
networks, with the reasons as follows. Per-flow or per-user level actions occur much
less frequent than per-packet actions, while per-packet actions are part of critical
forwarding behavior, which involves very few control actions
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(which are typically simply to read and enforce according the install state during forwarding
data). Actually, this separation concept is not new – routing protocols have the similar
abstraction together used with the traditional IP packet delivery, this abstraction is recently
being investigated in the IETF For CES working group. However, we emphasize the three
critical dimensions of future 4G networks: mobility, QoS and security, as well as other new
emerging or replacement components might appear, integrated into a unified framework
and allowing more extensibility for 4G networks design.
Fig.: - The decomposition of control plane and data plane
functionalities
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8.TRANSMISSION
An OFDM transmitter accepts data from an IP network, converting and encoding the
data prior to modulation. An IFFT inverse fast Fourier transform) transforms the OFDM
signal into an IF analog signal, which is sent to the RF transceiver. The receiver circuit
reconstructs the data by reversing this process. With orthogonal sub-carriers, the receiver can
separate and process each sub-carrier without interference from other sub-carriers. More
impervious to fading and multi-path delays than other wireless transmission techniques,
ODFM provides better link and communication quality.
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IP NETWORK
OFDM
MODULATION
TRANSMITTER
RF
TRANSMITTER
IFFT
DIAGRAM: OFDM MODULATION
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9. Wireless Technologies Used In 4G
1. OFDM
2. UWB
3. MILLIMETER WIRELESS
4. SMART ANTENNAS
5. LONG TERM POWER PREDICTION
6. SHEDULING AMONG USERS
7. ADAPTIVE MODULATION AND POWER CONTROL
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9.1 Orthogonal Frequency Division Multiplexing:
OFDM, a form of multi-carrier modulation, works by dividing the data stream
for transmission at a bandwidth B into N multiple and parallel bit 8streams,
spaced B/N apart. Each of the parallel bit streams has a much lower bit rate than
the original bit stream, but their summation can provide very high data rates. N
orthogonal sub-carriers modulate the parallel bit streams, which are then
summed prior to transmission.
An OFDM transmitter accepts data from an IP network, converting and
encoding the data prior to modulation. An IFFT (inverse fast Fourier transform)
transforms the OFDM signal into an IF analog signal, which is sent to the RF
transceiver. The receiver circuit reconstructs the data by reversing this process.
With orthogonal sub-carriers, the receiver can separate and process each subcarrier without interference from other sub-carriers. More impervious to fading
and multi-path delays than other wireless transmission techniques, ODFM
provides better link and communication quality.
Fig : :Orthogonal Frequency Division Multiplexing:
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OFDM BANDWIDTH DIVISION
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9.2 Error Correcting:
4G's error-correction will most likely use some type of concatenated
coding and
will provide multiple Quality of Service (QoS) levels. Forward error-correction
(FEC) coding adds redundancy to a transmitted message through encoding prior to
transmission. The advantages of concatenated coding (Viterbi/Reed-Solomon) over
convolution coding (Viterbi) are enhanced system performance through the
combining of two or more constituent codes (such as a Reed-Solomon and a
convolutional code) into one concatenated code. The combination can improve error
correction or combine error correction with error detection (useful, for example, for
implementing an Automatic Repeat Request if an error is found). FEC using
concatenated coding allows a communications system to send larger block sizes
while reducing bit-error rates.
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9.3 Millimeter Wireless:
Using the millimeter-wave band (above 20 GHz) for wireless service is
particularly interesting, due to the availability in this region of bandwidth
resources committed by the governments of some countries to unlicensed cellular
and other wireless applications. If deployed in a 4G system, millimeter wireless would
constitute only one of several frequency bands, with the 5 GHz band most likely
dominant.
FIG: MILLI-METER WIRELESS ANTENNA
9.4 Long Term Power Prediction:
Channels to different mobile users will fade independently. If the channel properties of
all users in a cell can be predicted a number of milliseconds ahead, then it would be
possible to distribute the transmission load among the users in an optimal way while
fulfilling certain specified constraints on throughput and delays. The channel timefrequency pattern will depend on the scattering environment and on the velocity of the
moving terminal.
In order to take the advantage the channel variability, we use OFDM
system with spacing between sub-carriers such that no interchannel interface occurs for
the worst case channel scenario (Low coherence bandwidth).A time-frequency grid
constituting of regions of one time slot and several subcarriers is used such that
the channel is fairly constant over each region. These time-frequency regions are then
allocated to the different users by a scheduling algorithm according to some criterion.
9.5 Scheduling among Users:
To optimize the system throughput, under specified QoS requirements and delay
constraints, scheduling will be used on different levels:
Among sectors:-In order to cope with co-channel interference among neighboring
sectors in adjacent cells, time slots are allocated according to the traffic load in each
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sector .Information on the traffic load is exchanged infrequently via an inquiry
procedure. In this way the interference can be minimized and higher capacity be
obtained.
After an inquiry to adjacent cells, the involved base stations determine the
allocation of slots to be used by each base station in each sector. The inquiry process
can also include synchronization information to align the transmission of packets at
different base stations to further enhance performance.
Among users:-Based on the time slot allocation obtained from inquiry process, the user
scheduler will distribute time-frequency regions among the users of each sector based
on their current channel predictions. Here different degrees of sophistication can be used
to achieve different transmission goals.
9.6 Adaptive modulation and power control:
In a fading environment and for a highly loaded system there will almost exist users
with good channel conditions. Regardless of the choice of criterion, which could be
either maximization of system throughput or equalization to user satisfaction, the
modulation format for the scheduled selected according to the predicted signal to
noise and interference ratio user is by using sufficiently small time-frequency bins
the channel can be made approximately constant within bins. We can thus use a flat
fading AWGN channel assumption. Furthermore since we have already determined
the time slot allocation, via the inquiry process among adjacent cells described above
we may use an aggressive power control scheme, while keeping the interference on
an acceptable level.
For every timeslot, the time-frequency bins in the grid represent separate channels.
For such channels the optimum rate and power allocation for maximizing the
throughput can be calculated under a total average power constraint. The
optimum strategy is to let one user, the one with best channel, transmit in each of the
parallel channels.
ISSUES:
The first issue deals with optimal choice of access technology, or how to be best
connected. Given that a user may be offered connectivity from more than one
technology at any one time, one has to consider how the terminal and an overlay
network choose the radio access technology suitable for services the user is
accessing.
There are several network technologies available today, which can be viewed as
complementary. For example, WLAN is best suited for high data rate indoor coverage.
GPRS or UMTS, on the other hand, are best suited formations wide coverage and can be
regarded as wide area networks, providing a higher degree of mobility. Thus a user of
the mobile terminal or the network needs to make the optimal choice of radio
access technology among all those available. A handover algorithm should both
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determine which network to connect to as well as when to perform a handover
between the different networks. Ideally, the handover algorithm would assure that the
best overall wireless link is chosen. The network selection strategy should
take into consideration the type of application being run by the user at the time
of handover. This ensures stability as well as optimal bandwidth for interactive and
background services.
The second issue regards the design of a mobility enabled IP networking
architecture, which contains the functionality to deal with mobility between access
technologies. This includes fast, seamless vertical (between heterogeneous
technologies) handovers (IP micro-mobility), quality of service (QoS), security and
accounting. Real-time applications in the future will require fast/seamless handovers for
smooth operation.
Mobility in IPv6 is not optimized to take advantage of specific mechanisms that
may be deployed in different administrative domains. Instead, IPv6 provides mobility in
a manner that resembles only simple portability.
To enhance Mobility in IPv6, ‘micro-mobility’ protocols (such as Hawaii [5], Cellular
IP [6] and Hierarchical Mobile IPv6 [7]) have been developed for seamless handovers
i.e. handover that result in minimal handover delay, minimal packet loss, and
minimal loss of communication state.
The third issue concerns the adaptation of multimedia transmission across 4G
networks. Indeed multimedia will be a main service feature of 4G networks, and
changing radio access networks may in particular result in drastic changes in the
network condition. Thus the framework for multimedia transmission must be
adaptive. In cellular networks such as UMTS, users compete for scarce and expensive
bandwidth.
Variable bit rate services provide a way to ensure service provisioning at
lower costs. In addition the radio environment has dynamics that renders it difficult to
provide a guaranteed network service. This requires that the services are adaptive and
robust against varying radio conditions.
High variations in the network Quality of Service (QoS) leads to significant
variations of the multimedia quality. The result could sometimes be unacceptable to the
users. Avoiding this requires choosing an adaptive encoding framework for multimedia
transmission. The network should signal QoS variations to allow the application to be
aware in real time of the network conditions. User interactions will help to ensure
personalized adaptation of the multimedia presentation.
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10. 4G Software
4G will likely become a unification of different wireless networks, including wireless
LAN technologies (e.g. IEEE 802.11), public cellular networks (2.5G, 3G), and even
personal area networks. Under this umbrella, 4G needs to support a wide range of
mobile devices that can roam across different types of networks (Cefriel ). These
devices would have to support different networks, meaning that one device would have
to have the capability of working on different networks. One solution to this “multinetwork functional device” is a software defined radio.
10.1
Software Defined Radio
A software defined radio is one that can be configured to any radio or frequency
standard through the use of software. For example, if one was a subscriber of Sprint and
moved into an area where Sprint did not have service, but Cingular did, the phone would
automatically switch from operating on a CDMA frequency to a TDMA frequency. In
addition, if a new standard were to be created, the phone would be able to support that
new standard with a simple software update. With current phones, this is impossible. A
software defined radio in the context of 4G would be able to work on different
broadband networks and would be able to transfer to another network seamlessly while
traveling outside of the user’s home network. A software defined radio’s best advantage
is its great flexibility to be programmed for emerging wireless standards. It can be
dynamically updated with new software without any changes in hardware and
infrastructure. Roaming can be an issue with different standards, but with a software
defined radio, users can just download the interface upon entering new territory, or the
software could just download automatically (Wang 2001). Of course, in order to be able
to download software at any location, the data must be formatted to some standard. This
is the job of the packet layer, which will split the data into small “packets.”
10.2
Packet Layer
The packet layer is a layer of abstraction that separates the data being transmitted from
the way that it is being transmitted. The Internet relies on packets to move files, pictures,
video, and other information over the same hardware. Without a packet layer, there
would need to be a separate connection on each computer for each type of information
and a separate network with separate routing equipment to move that information
around. Packets follow rules for how they are formatted; as long they follow these rules,
they can be any size and contain any kind of information, carrying this information from
any device on the network to another. Currently, there is little fault tolerance built into
cellular systems. If a little bit of the voice information is garbled or lost in a transfer
between locations, or if interference from other devices somehow affects the
transmission, there is nothing that can be done about it. Even though the loss is usually
negligible, it still can cause major problems with sensitive devices and can garble voice
information to a point where it is unintelligible. All of these problems contribute to a
low Quality of Service (QoS).
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10.3
Packets
Advantages
There are many advantages of packets and very few disadvantages. Packets are a proven
method to transfer information. Packets are:
More Secure Packets are inherently more secure for a variety of reasons:
• A predictable algorithm does not split packets — they can be of any size and contain
any amount of data. Packets can also travel across the network right after each other or
separated by packets from other devices; they can all take the same route over networks
or each take a different route.
• The data in packets can be encrypted using conventional data encryption methods.
There are many ways to encrypt data, including ROT-13, PGP, and RSA; the
information in a packet can be encoded using any one of them, because a packet doesn’t
care what kind of data it carries. Within the same packet, no matter how the data
segment is encrypted, the packet will still get from one place to the other in the same
way, only requiring that the receiving device know how to decrypt the data.
• There is no simple way to reconstruct data from packets without being the intended
recipient. Given that packets can take any route to their destination, it is usually hard to
piece them together without actually being at their intended destination. There are tools
to scan packets from networks; however, with the volume of packets that networks
receive and the volume of packets per each communication, it would take a large
amount of storage and processing power to effectively “sniff” a packet communication,
especially if the packets were encrypted.
More Flexible Current technologies require a direct path from one end of a
communication to the other. This limits flexibility of the current network; it is more like
a large number of direct communication paths than a network. When something happens
to the path in the current system, information is lost, or the connection is terminated (e.g.
a dropped call). Packets only require that there is an origin, a destination, and at least
one route between them. If something happens to one of the routes that a packet is using,
the routing equipment uses information in the packet to find out where it is supposed to
go and gives it an alternate route accordingly. Whether the problem with the network is
an outage or a slowdown, the combination of the data in the packet and the routing
equipment lead to the packet getting where it needs to go as quickly as possible.
More Reliable Packets know general things about the information they contain and can
be checked for errors at their destination. Error correction data is encoded in the last part
of the packet, so if the transmission garbles even one bit of the information, the
receiving device will know and ask for the data to be retransmitted. Packets are also
numbered so that if one goes missing, the device on the receiving end will know that
something has gone wrong and can request that the packet(s) in question be sent again.
In addition, when something does go wrong, the rest of the packets will find a way
around the problem, requiring that only the few lost during the actual instant of the
problem will need to be resent.
Proven Technology Packets are the underlying technology in essentially all data based
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communication. Since the beginning of the Internet over 30 years ago, packets have
been used for all data transmission. Technologies have evolved to ensure an almost
100% QoS for packet transmission across a network.
Easier to Standardize Current technologies use a variety of methods to break up voice
communication into pieces. None of these are compatible with each other. Packets,
however, are extremely compatible with various devices. They can carry different types
of information and be different sizes, but still have the same basic makeup to travel over
any network using any of the methods of transmission. Essentially, this enables different
technologies to be used to handle the same fundamental information
(Howstuffworks.com ). An example of the format of a packet carrying 896 bits of actual
information can be seen in Figure 9: The “Protocol” section would contain whatever
information was needed to explain what type of data was encoded; in the case of voice
using Voice over IP (VoIP), it would read: H.323 (Protocols.com ).
Extensible As shown by the growth of the Internet over the past few years, the capacity
of packets is expandable. They have moved from carrying short text messages to
carrying video, audio, and other huge types of data. As long as the capacity of the
transmitter is large enough, a packet can carry any size of information, or a large number
of packets can be sent carrying information cut up into little pieces. As long as a packet
obeys the standard for how to start and end, any data of any size can be encoded inside
of it; the transmission hardware will not know the difference.
Figure: Packet with 896-bit payload
Disadvantages
Unfortunately, to use packet, all cellular hardware will need to be upgraded or replaced.
Consumers will be required to purchase new phones, and providers will need to install
new equipment in towers. Essentially, the communication system will need to be rebuilt
from the ground up, running off of data packets instead of voice information. However,
given the current pace of technological development, most consumers buy new phones
every six to twelve months, and providers are constantly rolling out new equipment to
either meet expanding demand or to provide new or high-end services. All networks will
be compatible once the switch is completed, eliminating roaming and areas where only
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one type of phone is supported. Because of this natural pace of hardware replacement, a
mandated upgrade in a reasonable timeframe should not incur undue additional costs on
cellular companies or consumers. The technological disadvantage of using packets is not
really a disadvantage, but more of an obstacle to overcome. As the voice and data
networks are merged, there will suddenly be millions of new devices on the data
network. This will require either rethinking the address space for the entire Internet or
using separate address spaces for the wireless and existing networks.
10.4
Implementation of Packets
Current System: IPv4
Currently, the Internet uses the Internet Protocol version 4 (IPv4) to locate devices. IPv4
uses an address in the format of xxx.xxx.xxx.xxx where each set of three digits can
range from 0 to 255 (e.g 130.207.44.251). Though combinations are reserved, but this
address format allows for approximately 4.2 billion unique addresses. Almost all IP
addresses using IPv4 have been assigned, and given the number of new devices being
connected to the Internet every day, space is running out. As people begin to connect
refrigerators, cars, and phones to the Internet, a larger address space will be needed.
Recommended System: IPv6
The next generation addressing system uses the Internet Protocol version 6 (IPv6) to
locate devices. IPv6 has a much larger address space. Its addresses take the form
x:x:x:x:x:x:x:x where each x is the hexadecimal value that makes up one eighth of the
address. An example of this is: FEDC:BA98:7654:3210:FEDC:BA98:7654:3210 (The
Internet Engineering Task Force Network Working Group ). Using this address format,
there is room for approximately 3.40 _ 1038 unique addresses. This is approximately
8.05 _ 1028 times as large as the IPv4 address space and should have room for all wired
and wireless devices, as well as room for all of the foreseeable expansion in several
lifetimes. There are enough addresses for every phone to have a unique address. Thus,
phone in the future can use VoIP over the Internet instead of continuing to use their
existing network.
Voice over IP (VoIP)
Voice over IP is the current standard for voice communication over data networks.
Several standards already exist for VoIP, the primary one being International
Multimedia Telecommunications Consortium standard H.323. VoIP is already in use in
many offices to replace PBX-based systems and by several companies that offer cheap
long distance phone calls over the Internet, such as Net2Phone and Go2Call. VoIP
allows for flexibility the same way that data packets do; as far as the network is
concerned, VoIP packets are the same as any other packet. They can travel over any
equipment that supports packet-based communication and they receive all of the error
correction and other benefits that packets receive. There are many interconnects between
the data Internet and the phone network, so not only can VoIP customers communicate
with each other, they can also communicate with users of the old telephone system.
One other thing that VoIP allows is slow transition from direct, connection based
communication to VoIP communication. Backbones can be replaced, allowing old-style
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telephone users to connect to their central office (CO) the same way. However, the CO
will then connect to an IPv6 Internet backbone, which will then connect to the
destination CO. To the end user, there will not seem to be any difference, but the
communication will occur primarily over a packet-based system, yielding all of the
benefits of packets, outside of the short connections between either end of the
communication and their CO. Of course, in order to keep curious users from listening in
by “sniffing,” all data, including voice, should be encrypted while in transit.
Encryption
Two encryption/decryption techniques are commonly used: asymmetric and symmetric
encryption. Symmetric encryption is the more traditional form, where both sides agree
on a system of encrypting and decrypting messages — the reverse of the encryption
algorithm is the decryption algorithm. Modern symmetric encryption algorithms are
generic and use a key to vary the algorithm. Thus, two sides can settle on a specific key
to use for their communications. The problem then is the key transportation problem:
How do both sides get the key without a third party intercepting it? If an unauthorized
user receives the key, then he too can decrypt the messages. The solution to this problem
is asymmetric encryption. In symmetric encryption, the encryption and decryption
algorithms are inverses, but the key is the same. In asymmetric encryption, the keys are
inverses, but the algorithm is the same. The trick is that one cannot infer the value of one
key by using the other. In an asymmetric (also called publickey) system, an end user
makes one key public and keeps the other private. Then all parties know the algorithm
and the public key. If any party wishes to communicate with the users, that party can
encrypt the message using the public key, and only the user (with her private key) can
decrypt the message. Moreover, the user can prove that she generated a message by
encrypting it with her private key. If the encrypted message makes sense to other parties
when decrypted with the public key, then those parties know that the user must have
generated that message (Dankers, Garefalakis, Schaffelhofer, and Wright 2002, 181).
Situations exist in cellular wireless systems where either symmetric or asymmetric keys
are particularly useful. Asymmetric keys are useful for one-time connections, especially
when used to create a symmetric key for an extended connection. Meanwhile,
symmetric keys are smaller and faster, and thus are strongly preferred if key
transportation is not a problem. An excellent example of this is the GSM system’s
subscriber information card placed into each phone. The card holds a unique symmetric
key for each subscriber.
Flexibility
In reality, however, the usage of different encryption schemes depends on many factors,
including network data flow design. Thus, it is important that the encryption method be
able to change when other determining factors change. Al-Muhtadi, Mickunas, and
Campbell of University of Illinois at Urbana-Champaign showed great foresight in
admitting that “existing security schemes in 2G and 3G systems are inadequate, since
there is greater demand to provide a more flexible, reconfigurable, and scalable security
mechanism as fast as mobile hosts are evolving into full-fledged IP-enabled devices”
(Al-Muhtadi, Mickunas, and Campbell 2002, 60). Unfortunately, IPv6 can only protect
data in transmission. Individual applications may contain flaws in the processing of data,
thereby opening security holes. These holes may be remotely exploited, allowing the
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security of the entire mobile device to be compromised. Thus, any wireless device
should provide a process for updating the application software as security holes are
discovered and fixed.
Anti-Virus
As wireless devices become more powerful, they will begin to exhibit the same security
weaknesses as any other computer. For example, wireless devices may fall victim to
trojans or become corrupt with viruses. Therefore, any new wireless handheld device
should incorporate antivirus software. This software should scan all e-mail and files
entering through any port (e.g. Internet, beaming, or synchronizing), prompting the user
to remove suspicious software in the process. The antivirus software should also allow
secure, remote updates of the scanning software in order to keep up with the latest
viruses (NIST, U.S. Dept. of Commerce , 5-34).
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11. 4G Hardware
11.1
Ultra Wide Band Networks
Ultra Wideband technology, or UWB, is an advanced transmission technology that can
be used in the implementation of a 4G network. The secret to UWB is that it is typically
detected as noise. This highly specific kind of noise does not cause interference with
current radio frequency devices, but can be decoded by another device that recognizes
UWB and can reassemble it back into a signal. Since the signal is disguised as noise, it
can use any part of the frequency spectrum, which means that it can use frequencies that
are currently in use by other radio frequency devices (Cravotta ). An Ultra Wideband
device works by emitting a series of short, low powered electrical pulses that are not
directed at one particular frequency but rather are spread across the entire spectrum
(Butcher ). As seen in Figure 6, Ultra Wideband uses a frequency of between 3.1 to 10.6
GHz. The pulse can be called “shaped noise” because it is not flat, but curves across the
spectrum. On the other hand, actual noise would look the same across a range of
frequencies — it has no shape. For this reason, regular noise that may have the same
frequency as the pulse itself does not cancel out the pulse. Interference would have to
spread across the spectrum uniformly to obscure the pulse.
Figure: Switched Beam Antenna
UWB provides greater bandwidth — as much as 60 megabits per second, which is 6
times faster than today’s wireless networks. It also uses significantly less power, since it
transmits pulses instead of a continuous signal. UWB uses all frequencies from high to
low, thereby passing through objects like the sea or layers of rock. Nevertheless,
because of the weakness of the UWB signal, special antennas are needed to tune and
aim the signal.
11.2
Smart Antennas
Multiple “smart antennas” can be employed to help find, tune, and turn up signal
information. Since the antennas can both “listen” and “talk,” a smart antenna can send
signals back in the same direction that they came from. This means that the antenna
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system cannot only hear many times louder, but can also respond more loudly and
directly as well (ArrayComm2003). There are two types of smart antennas: Switched
Beam Antennas (as seen in Figure 7) have fixed beams of transmission, and can switch
from one predefined beam to another when the user with the phone moves throughout
the sector Adaptive Array Antennas represent the most advanced smart antenna
approach to date using a variety of new signal processing algorithms to locate and track
the user, minimize interference, and maximize intended signal reception (ArrayComm
2003).
Smart antennas can thereby:
• Optimize available power
• Increase base station range and coverage
• Reuse available spectrum
• Increase bandwidth
• Lengthen battery life of wireless devices
Figure: Adaptive Array Antenna
Although UWB and smart antenna technology may play a large role in a 4G system,
advanced software will be needed to process data on both the sending and receiving
side. This software should be flexible, as the future wireless world will likely be a
heterogeneous mix of technologies.
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12. Limitations of 3G and drivers for 4G
From its basic conception to the time of roll-out took around ten years for 2G; a similar
period will apply to 3G, which will commence service in 2001/2 and reach full
deployment by 2005. Thus by 2010 it will be time to deploy 4G networks and, working
backwards with the ten year cycle, it is clear that the year 2000 is appropriate to start
with visions for 4G and a research programme aimed at the key issues. The Mobile
VCE’s second phase research programme has been constructed to meet this aim.
The starting point was to look at current trends. Here we see a phenomenal growth in
mobiles with an estimated global user base that will exceed one billion by 2003. Already
mobile communications exceed fixed communications in several countries and it is
foreseen that mobile communications will subsume fixed by 2010 (fixed—mobile
convergence will be complete). Currently short messaging is booming, especially among
the younger generation, with averages of upwards of 100 messages per month
dominating monthly bills. Business take-up of SMS via information services is also
increasing and providing a start for mobile e-commerce, but this is currently very much
limited by the bit rates available. This will be improved with the introduction of GPRS.
In Europe the WAP system (using Wireless Markup Language—WML) has been slow
to gain market ground; in contrast, in Japan NTT DoC0oMo’s ‘i-mode’ system had over
10 million subscribers by summer 2000 and is picking up 50000 new customers per day.
Customers are already browsing the Internet, exchanging e-mail, conducting banking
and stock transactions, making flight reservations and checking news and weather via
HTML- based (Hyper Text Markup Language) text information on their phones. Java is
expected to be available on i-mode phones soon, allowing the download of agents,
games etc. and the introduction of location-based services. In Japan, the number of net
phones has now passed the number of wired Internet customers and is setting the trend
that others will surely follow when 3G opens up more bandwidth and improved quality.
Thus 3G will provide a significant step in the evolution of mobile personal
communications. Mobility appears to be one of the fundamental elements in the
evolution of the information society. As service provision based on ‘network centric’
architectures gradually gives way to the ‘edge-centric’ architectures, access is needed
from more and more places at all times. But can 3G deliver?
It is true that 3G can support multimedia Internet-type services at improved speeds and
quality compared to 2G. The W-CDMA based air-interface has been designed to provide
improved high-capacity coverage for medium bit rates (384 kbit/s) and limited coverage
at up to 2Mbit/s (in indoor environments). Statistical multiplexing on the air also
improves the efficiency of packet mode transmission. However, there are limitations
with 3G as follows:
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•
Extension to higher data rates is difficult with CDMA due to excessive
interference between services.
•
It is difficult to provide a full range of multirate services, all with different QoS
and performance requirements due to the constraints imposed on the core network by the
air interface standard. For example, it is not a fully integrated system.
In addition, the bandwidth available in the 2GHz bands allocated for 3G will soon
become saturated and there are constraints on the combination of frequency and time
division duplex modes imposed by regulators to serve different environments efficiently.
By the year 2010, one of the key enabling technology developments will be embedded
radio—the widespread availability and use of the $1 radio chip, which will evolve from
short-range wireless developments such as Bluetooth. Embedded radio will eventually
become as common as embedded microprocessors are today, with perhaps 50 such
devices in the typical home, the user being mostly unaware of their presence. As they
interact, in response to the user arriving home for example, they will form a home area
network (HAN). Similarly, such devices will be present in large numbers in vehicles
(the vehicular area network, or VAN), in personal belongings (the personal area
network, or PAN), in the public environment, etc. Such chips will serve as a means of
short-range communication between objects and devices, offering capabilities for
monitoring and control, in most cases without the knowledge or intervention of the user.
As a person moves between these environments such short-range links will allow their
personal profiles and preferences to move with them, with the hotel room automatically
configuring itself to their personal preferred temperatures, TV channels/interests,
lighting etc. However, the integration of such links with wide-area mobile access will
enable far more powerful service concepts, as mobile agents access this pervasive
network of sensors and access information on the user’s behalf to perform and even preempt their needs and wishes.
In the 1G to 2G transition, as well as a transition from analogue to digital we saw a
mono-service to multi-service transition. From 2G to 3G, as well as a mono-media to
multimedia transition we are also seeing a transition from person-to-person to person-tomachine interactions, with users accessing video, Internet/intranet and database feeds.
The 3G to 4G transition, supported by such technologies, will see a transition towards a
pre-dominance of automated and autonomously initiated machine-to-machine
interactions.
Such developments will of course be accompanied by ongoing evolution of already
anticipated 3G services, such as:
•
send/receive e-mail
•
Internet browsing (information)
•
on-line transactions (e-business)
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•
location-dependent information
•
company database access
•
large-file transfer.
These services in themselves represent an increase in requirements for accessing
information, for business and commercial transactions, as well as for a raft of new
location-dependent information services, all including significantly higher bit-rate
requirements. There is a requirement for a mixture of unicast, multicast and broadcast
service delivery with dynamic variation between application services both spatially and
temporally. Above all, there is a demand for ease of user access and manipulation, with
minimal user involvement—complexity hidden from the user—and intelligence to learn
and adapt with use.
From the above it will be seen that 4G will need to be highly dynamic in terms of
support for:
•
the users’ traffic
•
air interfaces and terminal types
•
radio environments
•
quality-of-service types
•
mobility patterns.
4G, then, must itself be dynamic and adaptable in all aspects, with built-in intelligence.
Thus a ‘software system’ rather than a hard-and-fixed physical system is indicated.
Integration, needed to reflect the convergence issues already mentioned, is also a key to
4G, in particular integration of the radio access and the core network elements, which
must be designed as a whole rather than segmented as in the past. Key drivers to 4G will
be:
•
a multitude of diverse devices (distributed, embedded, wearable, pervasive)
•
predominance of machine-to-machine communications
•
location-dependent and e-business applications
•
the extension of IF protocols to mobility and range of QoS
•
privacy and security
•
dynamic networking and air-interfaces
•
improved coverage mechanisms
•
improved and dynamic spectrum usage.
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13. 4G visions mapping to research topics
The Mobile VCE vision for 2010 is embodied in the five key elements shown in Fig. 2
and detailed as follows:
•
Fully converged services: Personal communications, information systems,
broadcast and entertainment will have merged into a seamless pool of content available
according to the user’s requirement. The user will have access to a wider range of
services and applications, available conveniently, securely and in a manner reflecting the
user’s personal preferences.
•
Ubiquitous mobile access: The dominant mode of access to this pool of content
will be mobile, accounting for all voice communications, the majority of high-speed
information services, and a significant proportion of broadcast and entertainment
services. Mobile access to commercial and retail services will be the norm, replacing
current practices in most cases.
•
Diverse user devices: The user will be served by a wide variety of low-cost
mobile devices to access content conveniently and seamlessly. These devices will
commonly be wearable—in some cases disposable— and will normally be powered
independently of the mains. Devices will interact with users in a multi sensory manner,
encompassing not only speech, hearing and sight but also the other human senses, and
biological and environmental data pertinent to the application. Special devices tailored
for people with disabilities will be common place
•
Autonomous networks: Underlying these systems will be highly autonomous
adaptive networks capable of self-management of their structure to meet the changing
and evolving demands of users for both services and capacity. Efficient and costeffective use of the radio spectrum will be an essential element of their operation, and
here, too, autonomy and self- management will be the norm.
•
Software dependency: Intelligent mobile agents will exist throughout the
networks and in user devices, and will act continually to simplify tasks and ensure
transparency to the user. These mobile agents will act at all levels, from managing an
individual user’s content preferences to organising and reconfiguring major elements of
networks.
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14. Research challenges
Analysis of the underlying technical challenges raised by the above vision and its five
elements has produced three research areas: Networks and services, Software based
systems, Wireless access. These form the basis of the Mobile VCE Phase 2 research
programme.
Networks and services
The aim of 3G is ‘to provide multimedia multirate mobile communications anytime and
anywhere’, though this aim can only be partially met. It will be uneconomic to meet this
requirement with cellular mobile radio only. 4G will extend the scenario to an all-IP
network (access + core) that integrates broadcast, cellular, cordless, WLAN (wireless
local area network), short-range systems and fixed wire. The vision is of integration
across these network—air interfaces and of a variety of radio environments on a
common, flexible and expandable platform — a ‘network of networks’ with distinctive
radio access connected to a seamless IP-based core network a (Fig. 3).
The functions contained in this vision will be:


a connection layer between the radio access and the IP core including mobility
management
internetworking between access schemes — inter and intra system, handover,
QoS negotiations, security and mobility
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
ability to interface with a range of new and existing radio interfaces
A vertical view of this 4G vision (Fig. 4) shows the layered structure of hierarchical
cells that facilitates optimisation for different applications and in different radio
environments. In this depiction we need to provide global roaming across all layers.
Both vertical and horizontal handover between different access schemes will be
available to provide seamless service and quality of service.
Network reconfigurability is a means of achieving the above scenario. This encompasses
terminal reconfigurability, which enables the terminal to roam across the different air
interfaces by exchanging configuration software (derived from the software radio
concept). It also provides dynamic service flexibility and trading of access across the
different networks by dynamically optimising the network nodes in the end-to- end
connection. This involves reconfiguration of protocol stacks, programmability of
network nodes and reconfigurability of base stations and terminals.
The requirement is for a distributed reconfiguration control. Fig. 5 demonstrates both
internal node and external network reconfigurability.
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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.
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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
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
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.
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15. MOBILITY MANAGEMENT
Features of mobility management in Ipv6:
-bit address space provides a sufficiently large number of addresses
-time audio and video transmission, short/ busty
connections of web applications, peer-to-peer applications, etc.
f processing – no header checksum at each relay,
fragmentation only at endpoints.
in its Care-of Address.
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16. Quality of Service (QoS):The Internet provides users with diverse and essential quality of service
(QoS), particularly given the increasing demand for a wide spectrum of network
services.
Many services, previously only provided by traditional circuit-switched networks,
can now be provided on the Internet. These services, depending on their inherent
characteristics, require certain degrees of QoS guarantees. Many technologies are
therefore being developed to enhance the QoS capability of IP networks. Among these
technologies, differentiated services (DiffServ) and MPLS are paving the way for
tomorrow’s QoS services portfolio.
DiffServ is based on a simple model where traffic entering a network is
classified, policed, and possibly conditioned at the edges of the network, and assigned
to different behavior aggregates. Each behavior aggregate is identified by a single DS
code point (DSCP). At the core of the network, packets are fast forwarded according to
the per-hop behavior (PHB) associated with the DSCP. By assigning traffic of
different classes to different DSCPs, the DiffServ network provides different
forwarding treatments and thus different levels of QoS.
MPLS integrates the label swapping forwarding paradigm with network layer
routing. First, an explicit path, called a label switched path (LSP), is determined, and
established using a signaling protocol. A label in the packet header, rather than the
IP destination address, is then used for making forwarding decisions in the network.
Routers that support MPLS are called label switched routers (LSRs). The labels can be
assigned to represent routes of various granularities, ranging from as coarse as the
destination network down to the level of each single flow.
Moreover, numerous traffic engineering functions have been effectively achieved
by MPLS. When MPLS is combined with DiffServ and constraint-based routing, they
become powerful and complementary abstractions for QoS provisioning in IP backbone
networks. Supporting QoS in 4G networks will be a major challenge due to varying
bitrates, channel characteristics, bandwidth allocation, fault-tolerance levels, and
handoff support among heterogeneous wireless networks. QoS support can occur at
the packet, transaction, circuit, user, and network levels
• Packet-level QoS applies to jitter, throughput, and error rate. Network resources such
as buffer space and access protocol are likely influences.
• Transaction-level QoS describes both the time it takes to complete a transaction and
the packet loss rate. Certain transactions may be time sensitive, while others cannot
tolerate any packet loss.
• Circuit-level QoS includes call blocking for new as well as existing calls. It
depends primarily on a network’s ability to establish and maintain the end-to-end
circuit. Call routing and location management are two important circuit-level attributes.
• User-level QoS depends on user mobility and application type. The new location
may not support the minimum QoS needed, even with adaptive applications. In a
complete wireless solution, the end-to-end communication between two users will
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likely involve multiple wireless networks. Because QoS will vary across different
networks, the QoS for such users will likely be the minimum level these networks
support.
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17. Security
Security in 4G networks mainly involves authentication, confidentiality, integrity, and
authorization for the access of network connectivity and QoS resources for the
MN’s flows.
Firstly, the MN needs to prove authorization and authenticate itself while
roaming to a new provider’s network. AAA protocols (such as Radius,
COPS or Diameter [10]) provide a framework for such support especially for
control plane functions (including key establishment between the MN and AR,
authenticating the MN with AAA server(s), and installing security policies in the
MN or ARs’ data plane such as encryption, encryption, and filtering), but they are not
well suited for mobility scenarios.
There needs to an efficient, scalable approach to address this. The
Extensible Authentication Protocol (EAP) [6], a recently developed IETF protocol,
provides a flexible framework for extensible network access authentication and
potentially could be useful.
Secondly, when QoS is concerned, QoS requests needs to be integrity-protected, and
moreover, before allocating QoS resources for an MN’s flow, authorization needs to be
performed to avoid denial of service attacks. This requires a hop-by-hop way of
dynamic key establishment between QoS-aware entities to be signaled on. Finally, most
security concerns in this paper lie in network layer functions: although security can also
be provided by higher layers above the network layer.
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18. Advantages:• Property owners can install their own access points.
– Spreads infrastructure cost.
• Reduced network access operational cost.
– Backbone access through wireless.
– Wired access through DSL at aggregation points.
• Ad hoc-like characteristics:
– Access points configure into access network.
– Some access points may be moving (bus, train).
• Multi-hop also could reduce costs in heterogeneous 3G networks.
– 802.11 to GPRS for example.
Fig.: - Example of Heterogeneous Network Multihop Architecture
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19. Applications
1) Application to Admission Control in Cellular Packet Networks:Based on the developing trends of mobile communication, 4G will have
broader bandwidth, higher data rate, and 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.
Emerging wireless technologies such as 4G tend to be packet-switched rather
than circuit-switched because the packet-based architecture allows for
better
sharing
of
limited wireless resources. In a packet network,
connections (packet flows) do not require dedicated circuits for the entire
duration of the connection. Unfortunately, this enhanced flexibility makes it more
difficult to effectively control the admission of connections into the network.
2) 4G in normal life:2.1 Traffic Control:Beijing is a challenging city for drivers, with or without an Olympics going
on. The growing middle class, and their new-found ability to purchase
automobiles, is increasing the number of passenger vehicles on the road at a
staggering annual rate of 30%. 4G networks can connect traffic control boxes to
intelligent transportation management systems wirelessly. This would create a
traffic grid that could change light cycle times on demand, e.g., keeping
some lights green longer temporarily to improve traffic flow. It also could
make vehicle-based on-demand “all green” routes for emergency vehicles re
sponding to traffic accidents, reducing the likelihood that those vehicles will
themselves be involved in an accident en route.
Using fiber to backhaul cameras means that the intelligence collected flows
one way: from the camera to the command center. Using a 4G network, those
images can also be sent from the command center back out to the streets.
Ambulances and fire trucks facing congestion can query various cameras to
choose an alternate route. Police, stuck in traffic on major thoroughfares,
can look ahead and make a decision as to whether it would be faster to stay on the
main roads or exit to the side roads.
2.2 Sensors on Public Vehicles:Putting a chemical-biological-nuclear (CBN)
warning sensor on
every
government-owned vehicle instantly creates a mobile fleet that is the equivalent of
an army of highly trained dogs. As these vehicles go about their daily duties
of law enforcement, garbage collection, sewage and water maintenance, etc.,
municipalities get the added benefit of early detection of CBN agents. The
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sensors on the vehicles can talk to fixed devices mounted on light poles
throughout the area, so positive detection can be reported in real time. And since
4G networks can include inherent geo-location without GPS, first responders will
know where the vehicle is when it detects a CBN agent.
3) Security:Beijing has already deployed cameras throughout the city and sends those images
back to a central command center for the OLYMPIC games2008. This is generally
done using fiber, which limits where the cameras can be hung, i.e., no fiber,
no camera. 4G networks allow Beijing to deploy cameras and backhaul them
wirelessly. And instead of having to backhaul every camera, cities can backhaul
every third or fifth or tenth camera, using the other cameras as router/repeaters.
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20. 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.
Although 4G wireless technology offers higher bit rates and the ability to roam across
multiple heterogeneous wireless networks, several issues require further research and
development. It is not clear if existing 1G and 2G providers would upgrade to 3G or
wait for it to evolve into 4G, completely bypassing 3G. The answer probably lies in the
perceived demand for 3G and the ongoing improvement in 2G networks to meet user
demands until 4G arrives.
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21. References
1.”eMobility Technology Platform Whitepaper”edited by Didier Bourse (Motorola Labs) and
Rahim Tafazolli (University of Surrey, CCSR)
2.”Intuitive Guide to Principle of Communications” copyright 2004 Charan Langton
3.”Paper on 4g evolution” By Abhijit Hota
4. www.wikipedia.com
5. www.4g.co.uk
6. www.wiley.com
7. www.mobilecomms-technology.com
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