Saturday, June 29, 2013
ABSTRACT
With the
rapid development of communication networks, it is expected that fourth
generation mobile systems will be launched within decades. Fourth generation
(4G) mobile systems focus on seamlessly integrating the existing wireless
technologies including GSM, wireless LAN, and Bluetooth. This contrasts with third
generation (3G), which merely focuses on developing new standards and hardware.
4G systems will support comprehensive and personalized services providing
stable system performance and quality service. This paper gives the details
about the need for mobile communication and its development in various
generations. In addition, the details about the working of 4G mobile
communication were given. Finally, it narrates how 4G mobile communication will
bring a new level of connectivity and convenece in communication.
1.INTRODUCTION
Communication is one of the
important areas of electronics and always been a focus for exchange of
information among parties at locations physically apart. There may be different
mode of communication. The communication may be wired or wireless between two
links. Initially the mobile communication was limited to between one pair of
users on single channel pair. Mobile communication has undergone many
generations. The first generation of the RF cellular used analog technology.
The modulation was FM and the air interface was FDMA. Second generation was an
offshoot of Personal Land Mobile Telephone System (PLMTS). It used Gaussian
Shift Keying modulation (GMSK). All these systems had practically no technology
in common and frequency bands, air interface protocol, data rates, number of
channels and modulation techniques all were difficult. Dynamic Quality of
Service (QoS) parameter was always on the top priority list. Higher
transmission bandwidth and higher efficiency usage had to be targeted. On this
background development of 3G mobile communication systems took place. In this
Time Division Duplex (TDD) mode technology using 5MHz channels was used. This
had no backward compatibility with any of the predecessors. But 3G appeared to
be somewhat unstable technology due to lack of standardization, licensing
procedures and terminal and service compatibility. Biggest single inhibitor of
any new technology in mobile communication is the mobile terminal availability
in the required quantity, with highest QoS and better battery life. The future
of mobile communication is FAMOUS-FUTUERE Advanced Mobile Universal Systems,
Wide-band TDMA, Wideband CDMA are some of the technologies. The data rates
targeted are 20MBPS. That will be the 4G in the mobile communication. 4G must
be hastened, as some of the video applications cannot be contained within
3G.
2.DEVELOPMENT
OF THE MOBILE
COMMUNICATION
The communication industry is undergoing cost saving
programs reflected by slowdown in the upgrade or overhaul of the
infrastructure, while looking for new ways to provide third generation (3G)
like services and features with the existing infrastructures. This has delayed
the large-scale development of 3G networks, and given rise to talk of 4G
technologies. Second generation (2G) mobile systems were very successful in the
previous decade. Their success prompted the development of third generation
(3G) mobile systems. While 2G systems such as GSM, andIS-95 etc. were designed
to carry speech and low bit-rate data. 3G systems were designed to provide
higher data-rate services. During the evolution from 2G to3G, a range of
wireless systems, including GPRS, IMT-2000, Bluetooth, WLAN, and Hiper LAN have
been developed. All these systems were designed independently, targeting
different service types, data rates, and users. As these systems all have their
own merits and shortcomings, there is no single system that is good to replace
all the other technologies. Instead of putting into developing new radio
interface and technologies for 4G systems, it is believed in establishing 4G
systems is a more feasible option.
3.
ARCHITECTURAL CHANGES IN 4G TECHNOLOGY
In 4G architecture, focus is on the aspect that
multiple networks are able to function in such a way that interfaces are
transparent to users and services. Multiplicities of access and service options
are going to be other key parts of the paradigm shift. In the present scenario
and with the growing popularity of Internet, a shift is needed to switch over
from circuit switched mode to packet switched mode of transmission. However 3G
networks and few others, packet switching is employed for delay insensitive
data transmission services. Assigning
packets to virtual channels and then multiple physical channels would be
possible when access options are expanded permitting better statistical
multiplexing. One would be looking for universal access and ultra connectivity,
which could be enabled by:
(a) Wireless
networks and with wire line networks.
(b)Emergence
of a true IP over the air technology.
(c) Highly
efficient use of wireless spectrum and resources.
(d)Flexible
and adaptive systems and networks.
4. SOME KEY
FEATURES OF 4G TECHNOLOGY
Some key features (mainly from the users point of
view) of 4G networks are:
1. High usability: anytime, anywhere, and with any
technology
2. Support for multimedia services at low transmission
cost
3. Personalization
4. Integrated services
First, 4G networks are all IP based heterogeneous
networks that allow users to use any system at any time and anywhere. Users
carrying an integrated terminal can use a wide range of applications provided
by multiple wireless networks.
Second, 4G systems provide not only telecommunications
services, but also data and multimedia services. To support multimedia services
high data-rate services with good system reliability will be provided. At the
same time, a low per-bit transmission cost will be maintained.
Third, personalized service will be provided by the
new generation network.
Finally, 4G
systems also provide facilities for integrated services. Users can use multiple
services from any service provider at the same time.
To migrate current systems to 4G with the features
mentioned above, we have to face number challenges. Some of them were discussed
below.
4.1 MULTIMODE
USER TERMINALS
In order to use large variety of services and wireless
networks in 4G systems, multimode user terminals are essential as they can
adopt different wireless networks by reconfiguring themselves. This eliminates
the need to use multiple terminals (or multiple hardware components in a
terminal). The most promising way of implementing multimode user terminals is
to adopt the software radio approach. Figure.1 shows the design of an ideal software
radio receiver.
The analog part of the receiver consists of an
antenna, a band pass filter (BPF), and a low noise amplifier (LNA). The
received analog signal is digitized by the analog to digital converter (ADC)
immediately after the analog processing. The processing in the next stage
(usually still analog processing in the conventional terminals) is then
performed by a reprogrammable base band digital signal processor (DSP). The
Digital Signal Processor will process the digitized signal in accordance with
the wireless environment.
4.2.
TERMINAL MOBILITY
In order to provide wireless services at any time and
anywhere, terminal mobility is a must in 4G infrastructures, terminal mobility
allows mobile client to roam across boundaries of wireless networks. There are
two main issues in terminal mobility: location management and handoff
management. With the location management, the system tracks and locates a
mobile terminal for possible connection. Location management involves handling
all the information about the roaming terminals, such as original and current
located cells, authentication information, and Quality of Service (QoS)
capabilities. On the other hand, handoff management maintains ongoing
communications when the terminal roams. MobileIPv6 (MIPv6) is a standardized
IP-based mobility protocol for Ipv6 wireless systems. In this design, each
terminal has an IPv6 home address whenever the terminal moves outside the local
network, the home address becomes invalid, and the terminal obtain a new Ipv6
address (called a care-of address) in the visited network. A binding between
the terminal’s home address and care-of address is updated to its home agent
in-order to support continuous communication.
4.3 PERSONAL
MOBILITY
In addition to terminal mobility, personal mobility is
a concern mobility management. Personal mobility concentrates on the movement
of users instead of user’s terminals, and involves the provision of personal
communications and personalized operating environments.
A personal operating environment, on the other hand,
is a service that enables adaptable service presentations inorder to fit the
capabilities of the terminal in use regardless of network types. Currently,
There are several frame works on personal mobility found in the literature.
Mobile-agent-based infrastructure is one widely studied solution. In this
infrastructure, each user is usually assigned a unique identifier and served by
some personal mobile agents (or specialized computer programs running on same
servers. These agents acts as intermediaries between the user and the Internet.
A user also belongs to a home network that has servers with the updated user
profile (including the current location of the user’s agents, user’s
performances, and currently used device descriptions). When the user moves from
his/her home network to a visiting network, his/her agents will migrate to the
new network. For example, when somebody makes a call request to the user, the
caller’s agent first locates user’s agent by making a location request to
user’s home network. By looking up user’s profile, his/her home network sends
back the location of user’s agent to the caller’s agent. Once the caller’s
agent identifies user’s location, the caller’s agent can directly communicate
with user’s agent. Different agents may be used for different services.
4.4 SECURITY
AND PRIVACY
Security requirements of 2G and 3G networks have been
widely studied in the literature. Different standards implement their security
for their unique security requirements. For
example, GSM provides highly secured voice
communication among users. However, the existing security schemes for wireless
systems are inadequate for 4G networks. The key concern in security designs for
4G networks is flexibility. As the existing security schemes are mainly
designed for specific services, such as voice service, they may not be
applicable to 4G environments that will consist of many heterogeneous systems.
Moreover, the key sizes and encryption and decryption algorithms of existing
schemes are also fixed. They become inflexible when applied to different
technologies and devices (with varied capabilities, processing powers, and
security needs). As an example, Tiny SESAME is a lightweight reconfigurable
security mechanism that provides security services for multimode or IP-based
applications in 4G networks.
5.
CONCLUSIONS
The future of mobile communication is FAMOUS-Future Advanced
Mobile Universal Systems. The data rates targeted are 20 MBPS. That will be the
FOURTH GENERATION 4G in the mobile communication technology. 4G must be
hastened, as some of the video applications cannot be contained within 3G.This
paper highlights that current systems must be implemented with a view of
facilitate to seamless integration into 4G infrastructure. Inorder to cope with
the heterogeneity of network services and standards, intelligence close to end
system is required to map the user application requests onto network services
that are currently available. This requirement for horizontal communication
between different access technologies has been regarded as a key element for 4G
systems. Finally, this paper describes how 4G mobile communication can be used
in any situation where an intelligent solution is required for interconnection
of different clients to networked applications aver heterogeneous wireless
networks.
