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4G by sachinknair000

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Two 4G candidate systems are commercially deployed: the Mobile WiMAX standard (first used in South Korea in 2006), and the first-release Long Term Evolution (LTE) standard (in Oslo, Norway and Stockholm, Sweden since 2009). It has however been debated if these first-release versions should be considered to be 4G or not, as discussed in the technical definition section below.

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									4G Technology

Wireless technology has transformed our lives in many ways. Until very recently, we needed a
computer wired to a port, to get online. Even wired telephones are becoming a thing of past.
Nowadays, we use our mobile phones for banking, to check ticket availability at a Cinema Hall,
and many more. Wireless communication is the transfer of information over a distance without
the use of enhanced electrical conductors or "wires”. And, Wireless networking refers to any
kind of networking that does not involve cables. It helps in saving the cost of cables for
networking in addition to providing the mobility.



What is 4G Technology, overview



There are different types of wireless networks defined on the basis of their size, range and data
transfer rate.

·    Wireless PAN - Personal area network Wireless Personal Area Networks

·    Wireless LAN - Local Area Network

·    Wireless MAN - Metropolitan Area Networks

·    Wireless WAN- Wide Area Networks

·    Mobile devices networks



Mobile networks have evolved tremendously in last 3 decades. Cellular concept was introduced
with 1G (‘G’ stands for generation) networks. Today, 4G technology is getting ready to storm the
markets. Not only that, research on 5G technology has already begun.



Evolution of Mobile Technologies

Zero Generation Technology (0G)

0G refers to pre-cell phone mobile telephony. Being the predecessors of the first generation of
cellular telephones, these systems are called 0G (zero generation) systems. Usually vehicle
mounted, they had the transceivers mounted in the vehicle trunk and dials & display mounted
near the driver seat.
Technologies used in 0G systems included PTT (Push to Talk), MTS (Mobile Telephone System),
IMTS (Improved Mobile Telephone Service), and AMTS (Advanced Mobile Telephone System).



First Generation Technology (1G)

1G refers to the first generation of wireless telecommunication technology, more popularly
known as cell phones. In 1G, Narrow band analogue wireless network is used; with this we can
have the voice calls. These services are provided with circuit switching. Through 1G, a voice call
gets modulated to a higher frequency of about 150MHz and up as it is transmitted between
radio towers using a technique called Frequency-Division Multiple Access (FDMA).



Different 1G standards prevalent were AMPS (Advanced Mobile Phone System) in the United
States, TACS (Total Access Communications System) in the United Kingdom, NMT (Nordic Mobile
Telephone), used in Nordic countries, Eastern Europe and Russia, etc.




Second Generation Technology

2G - 2G first appeared around late 1980’s; 2G system digitized the voice signal, as well as the
control link. It provided the facility of short message service (SMS) unlike 1G that had its prime
focus on verbal communication. Depending on the type of multiplexing used 2G technologies
can be divided into Time Division Multiple Access (TDMA) based and Code Division Multiple
Access (CDMA). 2G system offered better quality and much more capacity. 2G cellphone units
were generally smaller than 1G units, since they emitted less radio power.



Based on TDMA, Global System for Mobile communications (GSM) is the first European standard
& the first commercial network for use by the public for 2nd generation mobile (2G) telephony.
A typical 2G G.S.M network service uses 800/900MHz or 1800/1900 frequency spectrum. Typical
average data rate of GSM is 9.6 kbps. 2G CDMA (IS-95A) uses BPSK and offers data rate upto
14.4 kbps. The bandwidth of 2G is 30-200 KHz.



2.5G – GPRS (General Packet Radio Service) - 2.5G, which stands for "second and a half
generation," is a cellular wireless technology developed in between its predecessor, 2G, and its
successor, 3G. The term "second and a half generation" is used to describe 2G-systems that
have implemented a packet switched domain in addition to the circuit switched domain.
‘2.5G’ is an informal term, invented solely for marketing purposes, unlike "2G" or "3G" which are
officially defined standards based on those defined by the International Telecommunication
(ITU).

GPRS (CS1 to CS4) uses GMSK modulation with symbol rate (& modulation rate) of 270 ksym/s.
Typical data rate of GPRS is ~115 kbps. It can be used for services such as Wireless Application
Protocol (WAP) access, Multimedia Messaging Service (MMS) and for accessing internet.

IS-95B or cdmaOne is the evolved version of IS-95A and is also designated as 2.5G with
theoretical data rates of upto 115 kbps, with generally experienced rates of 64 kbps.



2.75 – EDGE (Enhanced Data rates for GSM Evolution) - EDGE (EGPRS) is an abbreviation for
Enhanced Data rates for GSM Evolution, is a digital mobile phone technology, invented by AT&T.
EDGE technology is an extended version of GSM & works in GSM networks. EDGE is add-on to
GPRS and can function on any network with GPRS deployed on it, provided the carrier
implements the necessary upgrades. It allows the clear and fast transmission of data. One need
not install any additional hardware and software in order to make use of EDGE Technology. Also,
there are no additional charges for utilizing this technology.



Uses 9 Modulation coding schemes (MCS1-9). MCS (1-4) uses GMSK, while MCS (5-9) uses 8PSK
modulation. 8PSK Increases throughput by 3x (8-PSK – 3 bits/symbol vs GMSK 1 bit/symbol).
Modulation bit rate is 810 kbps. It offers data rates of 384kbps, theoretically up to 473.6kbps.

 In March 2008, the International Telecommunications Union-Radio communications sector
(ITU-R) specified a set of requirements for 4G standards, named the International Mobile
Telecommunications Advanced (IMT-Advanced) specification, setting peak speed requirements
for 4G service at 100 megabits per second (Mbit/s) for high mobility communication (such as
from trains and cars) and 1 gigabit per second (Gbit/s) for low mobility communication (such as
pedestrians and stationary users).

Since the first-release versions of Mobile WiMAX and LTE support much less than 1 Gbit/s peak
bit rate, they are not fully IMT-Advanced compliant, but are often branded 4G by service
providers. On December 6, 2010, ITU-R recognized that these two technologies, as well as other
beyond-3G technologies that do not fulfill the IMT-Advanced requirements, could nevertheless
be considered "4G", provided they represent forerunners to IMT-Advanced compliant versions
and "a substantial level of improvement in performance and capabilities with respect to the
initial third generation systems now deployed".
Mobile WiMAX Release 2 (also known as WirelessMAN-Advanced or IEEE 802.16m') and LTE
Advanced (LTE-A) are IMT-Advanced compliant backwards compatible versions of the above two
systems, standardized during the spring 2011,[citation needed] and promising speeds in the
order of 1 Gbit/s. Services are expected in 2013.

As opposed to earlier generations, a 4G system does not support traditional circuit-switched
telephony service, but all-Internet Protocol (IP) based communication such as IP telephony. As
seen below, the spread spectrum radio technology used in 3G systems, is abandoned in all 4G
candidate systems and replaced by OFDMA multi-carrier transmission and other frequency-
domain equalization (FDE) schemes, making it possible to transfer very high bit rates despite
extensive multi-path radio propagation (echoes). The peak bit rate is further improved by smart
antenna arrays for multiple-input multiple-output (MIMO) communications.

The term "generation" used to name successive evolutions of radio networks in general is
arbitrary. There are several interpretations, and no official definition has been made despite the
consensus behind ITU-R's labels. From ITU-R's point of view, 4G is equivalent to IMT-Advanced
which has specific performance requirements as explained below. According to operators, a
generation of network refers to the deployment of a new non-backward-compatible technology.
The end user expects the next generation of network to provide better performance and
connectivity than the previous generation. Meanwhile, GSM, UMTS and LTE networks coexist;
and end-user will only receive the benefit of the new generation architecture when she
simultaneously: uses an access device compatible with the new infrastructure; is within range of
the new infrastructure; pays the provider for access to that new infrastructure.

The nomenclature of the generations generally refers to a change in the fundamental nature of
the service, non-backwards-compatible transmission technology, higher peak bit rates, new
frequency bands, wider channel frequency bandwidth in Hertz, and higher capacity for many
simultaneous data transfers (higher system spectral efficiency in bit/second/Hertz/site).

New mobile generations have appeared about every ten years since the first move from 1981
analog (1G) to digital (2G) transmission in 1992. This was followed, in 2001, by 3G multi-media
support, spread spectrum transmission and at least 200 kbit/s peak bit rate, in 2011/2012
expected to be followed by "real" 4G, which refers to all-Internet Protocol (IP) packet-switched
networks giving mobile ultra-broadband (gigabit speed) access.

While the ITU has adopted recommendations for technologies that would be used for future
global communications, they do not actually perform the standardization or development work
themselves, instead relying on the work of other standards bodies such as IEEE, The WiMAX
Forum and 3GPP.

In mid-1990s, the ITU-R standardization organization released the IMT-2000 requirements as a
framework for what standards should be considered 3G systems, requiring 200 kbit/s peak bit
rate. In 2008, ITU-R specified the IMT-Advanced (International Mobile Telecommunications
Advanced) requirements for 4G systems.
The fastest 3G-based standard in the UMTS family is the HSPA+ standard, which is commercially
available since 2009 and offers 28 Mbit/s downstream (22 Mbit/s upstream) without MIMO, i.e.
only with one antenna, and in 2011 accelerated up to 42 Mbit/s peak bit rate downstream using
either DC-HSPA+ (simultaneous use of two 5 MHz UMTS carrier)[4] or 2x2 MIMO. In theory
speeds up to 672 Mbit/s is possible, but has not been deployed yet. The fastest 3G-based
standard in the CDMA2000 family is the EV-DO Rev. B, which is available since 2010 and offers
15.67 Mbit/s downstream.

In telecommunications, 4G is the fourth generation of mobile phone mobile communication
technology standards. It is a successor to the third generation (3G) standards. A 4G system
provides mobile ultra-broadband Internet access, for example to laptops with USB wireless
modems, to smartphones, and to other mobile devices. Conceivable applications include
amended mobile web access, IP telephony, gaming services, high-definition mobile TV, video
conferencing, 3D television, and cloud computing.

Two 4G candidate systems are commercially deployed: the Mobile WiMAX standard (first used
in South Korea in 2006), and the first-release Long Term Evolution (LTE) standard (in Oslo,
Norway and Stockholm, Sweden since 2009). It has however been debated if these first-release
versions should be considered to be 4G or not, as discussed in the technical definition section
below.

In the United States, Sprint (previously Clearwire) has deployed Mobile WiMAX networks since
2008, and MetroPCS was the first operator to offer LTE service in 2010. USB wireless modems
have been available since the start, while WiMAX smartphones have been available since 2010,
and LTE smartphones since 2011. Equipment made for different continents is not always
compatible, because of different frequency bands. Mobile WiMAX is currently (April 2012) not
available for the European market.

								
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